JP5664954B2 - Taper hole forming apparatus, taper hole forming method, light modulation means, and modulation mask - Google Patents

Description

  The present invention relates to a tapered hole forming apparatus and a tapered hole forming method for forming a plurality of tapered holes in a workpiece by modulating light from a light source and irradiating the workpiece with the modulated light. The present invention also relates to a light modulation means and a modulation mask for modulating light from a light source.

  2. Description of the Related Art In recent years, components (workpieces) that are used in electronic devices and the like are required to be optically processed into various shapes with high accuracy. For example, in an inkjet head used in a printer or the like, it is required to precisely optically process the nozzles or ink flow paths of the inkjet head in order to obtain good ink ejection performance. Among these, the nozzle is provided with a tapered portion so that the ink discharge port is narrower than the base end portion.

  FIG. 47 shows a conventional laser processing apparatus 100 for forming nozzles using ablation by laser light. On the stage 109 of the laser processing apparatus 100, a workpiece 108 made of a resin plate such as polyimide and having nozzles formed by laser processing is placed. The pulsed laser light emitted from the laser light source 102 passes through the illumination optical system 103 that makes the light intensity distribution uniform, and then enters the mask 104. The mask 104 is formed by laminating a quartz glass layer 105 that transmits light and a light shielding film 106 made of a metal that shields light, and the light shielding film 106 has a circular opening at the center thereof. Part 106a. Therefore, of the laser light incident on the mask 104, only the laser light incident on the region corresponding to the opening 106 a of the light shielding film 106 is transmitted through the mask 104, and other light is transmitted by the light shielding film 106 of the mask 104. Shielded. The laser light transmitted through the mask 104 is imaged on the workpiece 108 by the imaging optical system 107. The light imaged and irradiated on the workpiece 108 has a circular pattern corresponding to the opening 106a of the light shielding film 106, and thus the workpiece 108 is processed into a circle. Thereby, the nozzle 110 provided with the tapered portion 110b is manufactured.

  As shown in FIG. 48A, between the taper angle of the taper portion 110b of the nozzle 110 manufactured by laser processing and the energy density (light intensity) of the irradiated laser light, the taper is reduced when the intensity is reduced. It is known that there is a relationship that the angle increases. By utilizing this relationship, it is possible to adjust the intensity of the irradiated laser beam and form the tapered portion 110b having a desired angle. For example, Patent Document 1 discloses an apparatus that forms the nozzle 110 by adjusting the intensity of laser light to be irradiated so as to form a tapered portion 110b having a predetermined angle.

JP 2002-67333 A

  In order to improve the production efficiency of components such as the nozzles described above, it may be required to manufacture a plurality of nozzles at once. In this case, for example, a plurality of tapered holes are formed in the workpiece at once by laser processing.

  By the way, in the processing by laser light, even when laser light having the same intensity is emitted from the laser processing apparatus to the region where the plurality of tapered holes are to be formed (tapered hole forming region), There are cases where the intensity of the laser beam when reaching the workpiece varies depending on the position of the tapered hole forming region. As described above, there are various factors as the reason why the intensity of the laser beam when reaching the workpiece varies depending on the position of the tapered hole forming region.

  For example, the following phenomenon can be considered as one factor. In machining with laser light, scattered objects are generated when a part of the workpiece is removed by ablation, but this scattered object absorbs and scatters the laser light when it reaches the workpiece. It has been known. Here, when the distance between each taper hole formation area is small, the scattered matter generated in one taper hole formation area may reach another taper hole formation area. In this case, the laser light applied to the other tapered hole forming region is absorbed and scattered not only by the scattered matter generated by its own processing but also by the scattered matter generated in one tapered hole forming region. Thus, in a situation where the influence of scattered objects from the adjacent tapered hole forming region can occur, in the group consisting of a plurality of tapered hole forming regions, the tapered hole forming region located at the center of the group is the end of the group. It is considered that the laser beam is more absorbed and scattered by the scattered matter than the tapered hole forming region located at. In this case, the intensity of the laser light when reaching the tapered hole forming region located at the center is smaller than the intensity of the laser light when reaching the tapered hole forming region located at the end.

  In addition, the following phenomena can be considered as other factors. When irradiating a plurality of regions with light imaged using a lens, the aberration of the light irradiated to each region is generally different. For example, when laser light is irradiated to a group of tapered hole forming regions by a laser processing apparatus, the aberration of light irradiated to the tapered hole forming region located at the end of the group is tapered at the central portion of the group. It can be considered that the aberration is larger than the aberration of light irradiated to the hole forming region. That is, the point image of the light irradiated to the tapered hole forming region located at the end of the group may be blurred compared to the point image of the light irradiated to the tapered hole forming region located at the center of the group. It is done. In this case, in the circular pattern of light irradiated to the tapered hole forming region located at the end of the group, the boundary part of the circular pattern (in the transition part between the strong light inside the circular pattern and the weak light outside the circular pattern) Yes, the inclined portion in the embodiment of the present invention to be described later becomes long.

  Further, as a further factor, the function of homogenizing the light intensity distribution of the laser light in the illumination optical system and the function of imaging the laser light on the workpiece in the imaging optical system vary slightly depending on the position. It is conceivable that the intensity of the laser light varies depending on the position. Such variations in the illumination optical system or the imaging optical system are due to a design limit (a limit that a complete design without unevenness due to position is generally difficult) and a manufacturing error during manufacturing.

  As described above, there is a relationship that the taper angle increases when the intensity of the laser beam is reduced. Therefore, when the intensity of the laser beam when reaching the workpiece varies depending on the position of the tapered hole forming region, the taper angles of the formed tapered holes are different from each other. Further, when the length of the boundary portion of the laser beam when reaching the workpiece is different depending on the position of the tapered hole forming region, the tapered angles of the formed tapered holes are different from each other.

  When the taper angle of the tapered hole formed in the workpiece varies depending on the position of the tapered hole forming region, the ink ejection performance of the nozzle configured using the obtained tapered hole also varies. If the ink ejection performance of the nozzles varies, it is not preferable because streaks and unevenness occur in the printed matter printed using the nozzles.

  An object of the present invention is to provide a tapered hole forming apparatus, a tapered hole forming method, an optical modulation means, and a modulation mask that can effectively solve such problems.

  The first aspect of the present invention modulates light emitted from a light source and irradiates the workpiece with the modulated light, whereby the workpiece has a plurality of tapers each having a penetrating portion or a bottom portion and a tapered portion. In a tapered hole forming apparatus for forming a hole, a light source that emits light, and a light modulation unit that is provided on an emission side of the light source and modulates the light from the light source and irradiates the workpiece with light. The light modulation means includes a plurality of unit modulation means each having a modulation amount distribution corresponding to a tapered hole, and the light that is modulated by each unit modulation means and applied to the workpiece is each a tapered hole. A unit gradation light having a light intensity distribution corresponding to the center gradation light, and each unit gradation light is irradiated to a region where a through-hole or a bottom portion of the tapered hole is formed in the workpiece, Located on the outer edge of the central part and on the workpiece And a region where the tapered portion of the tapered hole is formed, and an inclined portion where the light intensity decreases toward the outside, and a peripheral portion located at the outer edge of the inclined portion, The tapered hole forming apparatus is characterized in that the width of the inclined portion in one unit gradation light is different from the width of the inclined portion in at least one unit gradation light among the other unit gradation lights.

  According to the first aspect of the present invention, the width of the inclined portion in one unit gradation light among the unit gradation lights is equal to the width of the inclined portion in at least one unit gradation light among the other unit gradation lights. Is different. That is, the width of the inclined portion in the unit gradation light can be changed according to the position where each unit gradation light is irradiated. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  In the first aspect of the present invention, the unit gradation light is applied to the workpiece so that each unit gradation light is arranged in one or a plurality of rows on the workpiece, and the inclination in each unit gradation light is The width of the portion may increase as it goes to the end of the row.

  In the first aspect of the present invention, the unit gradation light is applied to the workpiece so that each unit gradation light is arranged in one or a plurality of rows on the workpiece, and the inclination in each unit gradation light is The width of the portion may become smaller toward the end of the row.

  The second aspect of the present invention modulates light emitted from a light source and irradiates the workpiece with the modulated light, whereby the workpiece has a plurality of tapers each having a penetrating portion or a bottom portion and a tapered portion. In a tapered hole forming apparatus for forming a hole, a light source that emits light, a modulation mask that is provided on the emission side of the light source and that modulates and emits light from the light source, and a modulation mask that is provided on the emission side of the modulation mask An imaging optical system that forms an image of the light modulated by irradiating and irradiating the workpiece, and the modulation mask has a plurality of modulation regions each having a modulation amount distribution corresponding to the tapered hole, Each modulation region is located at the center of the modulation mask that modulates the light irradiated to the region where the through-hole or bottom portion of the tapered hole is formed in the workpiece, and at the outer edge of the center of the modulation mask. The taper part of the taper hole is formed at A modulation mask inclined portion that modulates the light irradiated to the region to be irradiated, and a modulation mask peripheral portion located at an outer edge of the modulation mask inclined portion, each modulation mask inclined portion comprising a plurality of modulation unit regions, When the radius R of the point image distribution range of the imaging optical system is defined as R = 0.61λ / NA using the central wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system, the modulation unit The modulation unit conversion area obtained by converting the area into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system. A first modulation unit region that modulates light with a first modulation amount, and a second modulation unit region that modulates light with a second modulation amount, and the first modulation in each modulation unit region of the modulation mask tilt portion The unit area occupancy rate increases toward the outside of the modulation area. The width of the modulation mask inclined portion in one modulation region of each modulation region is different from the width of the modulation mask inclination portion in at least one modulation region of the other modulation regions. This is a taper hole forming device.

  According to the second aspect of the present invention, each modulation region of the modulation mask is located at the outer edge of the center portion of the modulation mask, and modulates light that irradiates the region where the tapered portion of the tapered hole is formed in the workpiece. Includes mask slope. Each modulation mask inclined portion is composed of a plurality of modulation unit regions, and the radius R of the point image distribution range of the imaging optical system is determined using the center wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system. = 0.61λ / NA, the modulation unit conversion region obtained by converting the modulation unit region into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system. It has become. For this reason, the width of the modulation mask inclined portion in one modulation region of each modulation region can be arbitrarily different from the width of the modulation mask inclined portion in at least one modulation region of the other modulation regions. Accordingly, the width of the inclined portion of each unit gradation light irradiated on the workpiece after being modulated by each modulation area of the modulation mask is arbitrarily changed according to the position irradiated with each unit gradation light. Can do. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

In the second aspect of the present invention, the modulation area is arranged such that each modulation area is arranged in a line or a plurality of lines on the modulation mask, and the width of the modulation mask inclined portion in each modulation area increases toward the end of the line. It may be.
In this case, in the modulation mask inclined portion, the number of the modulation unit regions arranged in the width direction of the modulation mask inclined portion may increase toward the end of the column.
Alternatively, in the modulation mask inclined part, the dimension in the width direction of the modulation unit regions arranged in the width direction of the modulation mask inclined part may increase toward the end of the column.

In the second aspect of the present invention, the modulation areas are arranged such that each modulation area is arranged in a line or a plurality of lines on the modulation mask, and the width of the modulation mask inclined portion in each modulation area decreases toward the end of the line. It may be.
In this case, in the modulation mask inclined part, the number of the modulation unit regions arranged in the width direction of the modulation mask inclined part may become smaller toward the end of the column.
Alternatively, in the modulation mask inclined part, the dimension in the width direction of the modulation unit regions arranged in the width direction of the modulation mask inclined part may become smaller toward the end of the column.

  In the second aspect of the present invention, the first modulation amount in the first modulation unit region and the second modulation amount in the second modulation unit region are different from each other by a predetermined phase modulation amount that is an odd multiple of 180 degrees. May be. In this case, in the modulation mask inclined portion, the difference between the occupancy rate of the first modulation unit region and the occupancy rate of the inclined portion second modulation region in each modulation unit region is directed outward from the modulation mask inclined portion. Monotonously decreases.

  In the second aspect of the present invention, the first modulation unit region may include a light shielding layer that shields light. In this case, in the modulation mask inclined portion, the occupation ratio of the first modulation unit region in each modulation unit region monotonously increases toward the outside of the modulation mask inclined portion.

  A third aspect of the present invention modulates light emitted from a light source, and irradiates the workpiece with the modulated light, whereby the workpiece has a plurality of tapers each having a penetrating portion or a bottom portion and a tapered portion. In the tapered hole forming method for forming a hole, a light source for emitting light is prepared, and light from the light source is modulated by a light modulation means provided on the light emitting side of the light source, and light is applied to the workpiece. The light modulation means includes a plurality of unit modulation means each having a modulation amount distribution corresponding to the tapered hole, and is modulated by each unit modulation means and irradiated onto the workpiece. Each of the light beams is unit gradation light having a light intensity distribution corresponding to the tapered hole, and each unit gradation light is irradiated to a region where the through-hole or bottom portion of the tapered hole is formed in the workpiece. Center portion to be positioned on the outer edge of the central portion In addition, the region where the tapered portion of the tapered hole is formed in the workpiece, and the light intensity decreases as it goes outward, and the peripheral portion located at the outer edge of the inclined portion, A taper characterized in that the width of the inclined portion in one unit gradation light of each unit gradation light is different from the width of the inclined portion in at least one unit gradation light among the other unit gradation lights. This is a hole forming method.

  According to the third aspect of the present invention, the width of the inclined portion in one unit gradation light among the unit gradation lights is equal to the width of the inclined portion in at least one unit gradation light among the other unit gradation lights. Is different. That is, the width of the inclined portion in the unit gradation light can be changed according to the position where each unit gradation light is irradiated. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  A fourth aspect of the present invention modulates light emitted from a light source and irradiates the workpiece with the modulated light, whereby the workpiece has a plurality of tapers having a penetrating portion or a bottom portion and a tapered portion. In a tapered hole forming method for forming a hole, a step of preparing a light source that emits light, a step of modulating light from the light source by a modulation mask provided on the emission side of the light source, and a step provided on the emission side of the modulation mask And imaging the light modulated by the modulation mask by the imaging optical system, and irradiating the workpiece. The modulation mask has a plurality of modulation amount distributions each corresponding to a tapered hole. Each modulation region has a modulation mask central portion for modulating light irradiated to a region where a through-hole or a bottom portion of the tapered hole is formed in the workpiece, and an outer edge of the modulation mask central portion. Located on the work piece And a modulation mask inclined portion that modulates light irradiated to a region where the tapered portion of the tapered hole is formed, and a modulation mask peripheral portion located at an outer edge of the modulation mask inclined portion, and each modulation mask inclined portion includes: The radius R of the point image distribution range of the imaging optical system is R = 0.61λ /, using the center wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system. When defined as NA, the modulation unit conversion region obtained by converting the modulation unit region into the imaging surface of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system. Each modulation unit region includes a first modulation unit region that modulates light with a first modulation amount and a second modulation unit region that modulates light with a second modulation amount. Occupancy rate of the first modulation unit area in each modulation unit area The width of the slope of the modulation mask in one modulation region of each modulation region is monotonously increased or decreased toward the outside of the modulation region, and the modulation mask in at least one modulation region of the other modulation regions It is a taper hole forming method characterized by being different from the width of the inclined portion.

  According to the fourth aspect of the present invention, each modulation region of the modulation mask is located on the outer edge of the center portion of the modulation mask, and modulates the light irradiated to the region where the tapered portion of the tapered hole is formed in the workpiece. Includes mask slope. Each modulation mask inclined portion is composed of a plurality of modulation unit regions, and the radius R of the point image distribution range of the imaging optical system is determined using the center wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system. = 0.61λ / NA, the modulation unit conversion region obtained by converting the modulation unit region into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system. It has become. For this reason, the width of the modulation mask inclined portion in one modulation region of each modulation region can be arbitrarily different from the width of the modulation mask inclined portion in at least one modulation region of the other modulation regions. Accordingly, the width of the inclined portion of each unit gradation light irradiated on the workpiece after being modulated by each modulation area of the modulation mask is arbitrarily changed according to the position irradiated with each unit gradation light. Can do. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  A fifth aspect of the present invention modulates light emitted from a light source and irradiates the workpiece with the modulated light, whereby the workpiece has a plurality of tapers each having a penetrating portion or a bottom portion and a tapered portion. The light modulating means for forming the hole has a plurality of unit modulating means each having a modulation amount distribution corresponding to the tapered hole, and the light that is modulated by each unit modulating means and irradiated to the workpiece is each tapered. A unit gradation light having a light intensity distribution corresponding to the hole, each unit gradation light is irradiated to a region where a through-hole or a bottom part of the tapered hole is formed in the workpiece, Located at the outer edge of the central portion, the inclined portion in which the tapered portion of the tapered hole is formed in the workpiece, and the light intensity decreases toward the outside, and the outer edge of the inclined portion. The peripheral part, The width of the inclined portion in one unit gradation light among the unit gradation lights is different from the width of the inclined portion in at least one unit gradation light among the other unit gradation lights. Light modulation means.

  According to the fifth aspect of the present invention, the width of the inclined portion in one unit gradation light among the unit gradation lights is equal to the width of the inclined portion in at least one unit gradation light among the other unit gradation lights. Is different. That is, the width of the inclined portion in the unit gradation light can be changed according to the position where each unit gradation light is irradiated. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  A sixth aspect of the present invention is provided between a light source that emits light and an imaging optical system that forms an image of light and irradiates the workpiece, and modulates the light from the light source and modulates the light. In a modulation mask that emits light toward the imaging optical system, the workpiece has a plurality of penetrating portions or bottom portions, and a tapered portion by light irradiated on the workpiece from the imaging optical system. A taper hole is formed, and the modulation mask has a plurality of modulation regions each having a modulation amount distribution corresponding to the taper hole, and each modulation region has a through-hole or a bottom portion of the taper hole in the workpiece. A modulation mask that modulates the light irradiated to the region to be irradiated, and a modulation that modulates the light irradiated to the region where the tapered portion of the workpiece is formed at the outer edge of the modulation mask central portion. Mask inclination part and the modulation mask inclination Each of the modulation mask inclined portions is composed of a plurality of modulation unit regions, and the radius R of the point image distribution range of the imaging optical system is set to the center wavelength λ of the light. When R = 0.61λ / NA is defined using the numerical aperture NA on the exit side of the imaging optical system, the modulation unit conversion area obtained by converting the modulation unit area into the imaging plane of the imaging optical system is The modulation unit region is smaller than the radius of the point image distribution range of the imaging optical system in at least one direction. Each modulation unit region includes a first modulation unit region that modulates light by a first modulation amount, And the occupancy ratio of the first modulation unit area in each modulation unit area of the modulation mask inclined portion monotonously increases or decreases toward the outside of the modulation area. Change in one of the modulation areas. The width of the mask ramps, a modulation mask, characterized in that is different from the width of the modulation mask inclined portion in at least one of the modulation area of the other modulation area.

  According to the sixth aspect of the present invention, each modulation region of the modulation mask is located on the outer edge of the central portion of the modulation mask, and modulates light that irradiates the region where the tapered portion of the tapered hole is formed in the workpiece. Includes mask slope. Each modulation mask inclined portion is composed of a plurality of modulation unit regions, and the radius R of the point image distribution range of the imaging optical system is determined using the center wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system. = 0.61λ / NA, the modulation unit conversion region obtained by converting the modulation unit region into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system. It has become. For this reason, the width of the modulation mask inclined portion in one modulation region of each modulation region can be arbitrarily different from the width of the modulation mask inclined portion in at least one modulation region of the other modulation regions. Accordingly, the width of the inclined portion of each unit gradation light irradiated on the workpiece after being modulated by each modulation area of the modulation mask is arbitrarily changed according to the position irradiated with each unit gradation light. Can do. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  The seventh aspect of the present invention modulates the light emitted from the light source and irradiates the workpiece with the modulated light, whereby the workpiece has a plurality of tapers having a penetrating portion or a bottom portion and a tapered portion. In a tapered hole forming apparatus for forming a hole, a light source that emits light, and a light modulation unit that is provided on an emission side of the light source and modulates the light from the light source and irradiates the workpiece with light. The light modulation means includes a plurality of unit modulation means each having a modulation amount distribution corresponding to a tapered hole, and the light that is modulated by each unit modulation means and applied to the workpiece is each a tapered hole. A unit gradation light having a light intensity distribution corresponding to the center gradation light, and each unit gradation light is irradiated to a region where a through-hole or a bottom portion of the tapered hole is formed in the workpiece, Located outside the center part and on the workpiece And the peripheral portion irradiated to the peripheral region of the region where the tapered portion of the tapered hole is formed, and the light intensity of the central portion in one unit gradation light among each unit gradation light is the other unit The taper hole forming apparatus is characterized in that it differs from the light intensity of the central portion of at least one unit gradation light of gradation light.

  According to the seventh aspect of the present invention, the light intensity of the central portion of one unit gradation light among the unit gradation lights is the light of the central portion of at least one unit gradation light of the other unit gradation lights. It is different from strength. That is, the light intensity of the central portion of the unit gradation light can be changed according to the position where each unit gradation light is irradiated. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  In the seventh aspect of the present invention, the unit gradation light is irradiated to the workpiece so that each unit gradation light is arranged in one or a plurality of rows on the workpiece, and a central portion in each unit gradation light The light intensity may decrease as it goes toward the end of the row.

  In the seventh aspect of the present invention, the unit gradation light is irradiated to the workpiece so that each unit gradation light is arranged in one or a plurality of rows on the workpiece, and a central portion in each unit gradation light The light intensity of may increase as it goes to the end of the row.

  The eighth aspect of the present invention modulates light emitted from a light source and irradiates the workpiece with the modulated light, whereby the workpiece has a plurality of tapers each having a penetrating portion or a bottom portion and a tapered portion. In a tapered hole forming apparatus for forming a hole, a light source that emits light, a modulation mask that is provided on the emission side of the light source and that modulates and emits light from the light source, and a modulation mask that is provided on the emission side of the modulation mask An imaging optical system that forms an image of the light modulated by irradiating and irradiating the workpiece, and the modulation mask has a plurality of modulation regions each having a modulation amount distribution corresponding to the tapered hole, Each modulation region is located at the center of the modulation mask that modulates the light applied to the region where the through-hole or bottom portion of the tapered hole is formed in the workpiece, and outside the center portion of the modulation mask. The taper part of the taper hole is formed at A modulation mask peripheral portion that modulates light irradiated to a peripheral region of the region to be irradiated, each modulation mask central portion comprising a plurality of modulation unit regions, and a radius of a point image distribution range of the imaging optical system When R is defined as R = 0.61λ / NA using the center wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system, the modulation unit region is defined as the imaging plane of the imaging optical system. The converted modulation unit conversion region is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system, and each modulation unit region has a first modulation for modulating light with a first modulation amount. The unit area and the second modulation unit area for modulating light with the second modulation amount, and the occupancy ratio of the first modulation unit area in the modulation unit area at the center of each modulation mask is set to a predetermined value. The modulation mass in one modulation region of each modulation region The taper hole formation is characterized in that the occupation ratio of the first modulation unit area in the central portion is different from the occupation ratio of the first modulation unit area in the central portion of the modulation mask in at least one of the other modulation areas Device.

  According to the eighth aspect of the present invention, each modulation region of the modulation mask includes a modulation mask central portion that modulates light irradiated to a region where a through-hole or a bottom portion of the tapered hole is formed in the workpiece. . The central portion of each modulation mask is composed of a plurality of modulation unit regions, and the radius R of the point image distribution range of the imaging optical system is determined using the center wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system. = 0.61λ / NA, the modulation unit conversion region obtained by converting the modulation unit region into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system. It has become. Each modulation unit region includes a first modulation unit region that modulates light with a first modulation amount, and a second modulation unit region that modulates light with a second modulation amount. The occupation ratio of the first modulation unit area in the modulation unit area at the center of each modulation mask is set to a predetermined value. Therefore, the light intensity of the central portion of each unit gradation light irradiated to the workpiece after being modulated by each modulation area of the modulation mask is arbitrarily changed according to the position where each unit gradation light is irradiated. be able to. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  In the eighth aspect of the present invention, the modulation areas are arranged such that each modulation area is arranged in a line or a plurality of lines on the modulation mask, and the occupancy ratio of the first modulation unit area at the center of the modulation mask in each modulation area is: It may be monotonously increasing or decreasing toward the end of the row.

In the eighth aspect of the present invention, the first modulation amount in the first modulation unit region and the second modulation amount in the second modulation unit region are different from each other by a predetermined phase modulation amount that is an odd multiple of 180 degrees. May be.
In this case, the difference between the occupancy ratio of the first modulation unit area and the occupancy ratio of the second modulation unit area at the central portion of the modulation mask of each modulation area may decrease monotonously toward the end of the column.
Alternatively, the difference between the occupancy ratio of the first modulation unit area and the occupancy ratio of the second modulation unit area at the central portion of the modulation mask in each modulation area may increase monotonously toward the end of the column.

In the eighth invention, the first modulation unit region may include a light shielding layer for shielding light.
In this case, the occupation ratio of the first modulation unit region at the center of the modulation mask of each modulation region may increase monotonously toward the end of the column.
Alternatively, the occupancy ratio of the first modulation unit region in the central portion of the modulation mask of each modulation region may monotonously decrease toward the end of the column.

  A ninth aspect of the present invention modulates light emitted from a light source and irradiates the workpiece with the modulated light, whereby the workpiece has a plurality of tapers each having a penetrating portion or a bottom portion and a tapered portion. In the tapered hole forming method for forming a hole, a light source for emitting light is prepared, and light from the light source is modulated by a light modulation means provided on the light emitting side of the light source, and light is applied to the workpiece. The light modulation means includes a plurality of unit modulation means each having a modulation amount distribution corresponding to the tapered hole, and is modulated by each unit modulation means and irradiated onto the workpiece. Each of the light beams is unit gradation light having a light intensity distribution corresponding to the tapered hole, and each unit gradation light is irradiated to a region where the through-hole or bottom portion of the tapered hole is formed in the workpiece. A central portion to be placed on the outside of the central portion And a peripheral portion irradiated to a peripheral region of the region where the tapered portion of the tapered hole is formed in the workpiece, and light in a central portion of one unit gradation light among each unit gradation light The intensity is different from the light intensity of the central portion of at least one unit gradation light among the other unit gradation lights.

  According to the ninth aspect of the present invention, the light intensity of the central portion of one unit gradation light among the unit gradation lights is the light of the central portion of at least one unit gradation light of the other unit gradation lights. It is different from strength. That is, the light intensity of the central portion of the unit gradation light can be changed according to the position where each unit gradation light is irradiated. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  A tenth aspect of the present invention modulates light emitted from a light source and irradiates the workpiece with the modulated light, whereby the workpiece has a plurality of tapers each having a penetrating portion or a bottom portion and a tapered portion. In a tapered hole forming method for forming a hole, a step of preparing a light source that emits light, a step of modulating light from the light source by a modulation mask provided on the emission side of the light source, and a step provided on the emission side of the modulation mask And imaging the light modulated by the modulation mask by the imaging optical system, and irradiating the workpiece. The modulation mask has a plurality of modulation amount distributions each corresponding to a tapered hole. Modulation regions, each modulation region having a modulation mask central portion that modulates light irradiated to a region where a through-hole or a bottom portion of a tapered hole is formed in the workpiece, and an outer side of the modulation mask central portion Located on the work piece A modulation mask peripheral portion that modulates light irradiated to the peripheral region of the region where the tapered portion of the tapered hole is formed, and each modulation mask central portion includes a plurality of modulation unit regions, and When the radius R of the point image distribution range of the image optical system is defined as R = 0.61λ / NA using the center wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system, the modulation unit region is The modulation unit conversion area converted into the imaging plane of the imaging optical system is smaller than the radius of the point image distribution range of the imaging optical system in at least one direction. A first modulation unit region that modulates with a modulation amount of 1 and a second modulation unit region that modulates light with a second modulation amount. The occupation ratio is set to a predetermined value for each modulation area. The occupation ratio of the first modulation unit area at the center of the modulation mask in one modulation area is different from the occupation ratio of the first modulation unit area at the center of the modulation mask in at least one of the other modulation areas. This is a method of forming a tapered hole.

  According to the tenth aspect of the present invention, each modulation region of the modulation mask includes a modulation mask central portion that modulates light irradiated to a region where a through-hole or a bottom portion of the tapered hole is formed in the workpiece. . The central portion of each modulation mask is composed of a plurality of modulation unit regions, and the radius R of the point image distribution range of the imaging optical system is determined using the center wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system. = 0.61λ / NA, the modulation unit conversion region obtained by converting the modulation unit region into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system. It has become. Each modulation unit region includes a first modulation unit region that modulates light with a first modulation amount, and a second modulation unit region that modulates light with a second modulation amount. The occupation ratio of the first modulation unit area in the modulation unit area at the center of each modulation mask is set to a predetermined value. Therefore, the light intensity of the central portion of each unit gradation light irradiated to the workpiece after being modulated by each modulation area of the modulation mask is arbitrarily changed according to the position where each unit gradation light is irradiated. be able to. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  The eleventh aspect of the present invention modulates the light emitted from the light source and irradiates the workpiece with the modulated light, whereby the workpiece has a plurality of tapers each having a penetrating portion or a bottom portion and a tapered portion. The light modulating means for forming the hole has a plurality of unit modulating means each having a modulation amount distribution corresponding to the tapered hole, and the light that is modulated by each unit modulating means and irradiated to the workpiece is each tapered. A unit gradation light having a light intensity distribution corresponding to the hole, each unit gradation light is irradiated to a region where a through-hole or a bottom part of the tapered hole is formed in the workpiece, A peripheral portion that is located outside the central portion and is irradiated to a peripheral region of a region where the tapered portion of the tapered hole is formed in the workpiece, and one unit floor of each unit gradation light Light intensity at the center of dimming A light modulating means, characterized in that is different from the light intensity of the central part of at least one unit gray light of the other unit gray level light.

  According to the eleventh aspect of the present invention, the light intensity of the central portion of one unit gradation light among the unit gradation lights is the light of the central portion of at least one unit gradation light among the other unit gradation lights. It is different from strength. That is, the light intensity of the central portion of the unit gradation light can be changed according to the position where each unit gradation light is irradiated. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  A twelfth aspect of the present invention is provided between a light source that emits light and an imaging optical system that images light and irradiates a workpiece, and modulates light from the light source and modulates the light. In a modulation mask that emits light toward the imaging optical system, the workpiece has a plurality of penetrating portions or bottom portions, and a tapered portion by light irradiated on the workpiece from the imaging optical system. A taper hole is formed, and the modulation mask has a plurality of modulation regions each having a modulation amount distribution corresponding to the taper hole, and each modulation region has a through-hole or a bottom portion of the taper hole in the workpiece. The light irradiated to the peripheral area of the modulation mask central portion for modulating the light irradiated to the region to be irradiated and the region where the tapered portion of the taper hole is formed in the workpiece, located outside the modulation mask central portion. A modulation mask peripheral portion for modulating The central portion of each modulation mask is composed of a plurality of modulation unit regions, and uses the radius R of the point image distribution range of the imaging optical system, the center wavelength λ of light, and the numerical aperture NA on the exit side of the imaging optical system. When R = 0.61λ / NA is defined, the modulation unit conversion region obtained by converting the modulation unit region into the imaging surface of the imaging optical system is smaller than the radius of the point image distribution range of the imaging optical system. Each modulation unit region is small in at least one direction, and each modulation unit region includes: a first modulation unit region that modulates light with a first modulation amount; and a second modulation unit region that modulates light with a second modulation amount. Thus, the occupancy ratio of the first modulation unit area in the modulation unit area in the center of each modulation mask is set to a predetermined value, and the first modulation in the center of the modulation mask in one modulation area among the modulation areas. The unit area occupancy is at least of other modulation areas. One of it is modulated mask, characterized in that is different from the first occupation of the modulator unit area of the modulating mask central portion in the modulation region.

  According to the twelfth aspect of the present invention, each modulation region of the modulation mask includes a modulation mask central portion that modulates light irradiated to a region where a through-hole or a bottom portion of the tapered hole is formed in the workpiece. . The central portion of each modulation mask is composed of a plurality of modulation unit regions, and the radius R of the point image distribution range of the imaging optical system is determined using the center wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system. = 0.61λ / NA, the modulation unit conversion region obtained by converting the modulation unit region into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system. It has become. Each modulation unit region includes a first modulation unit region that modulates light with a first modulation amount, and a second modulation unit region that modulates light with a second modulation amount. The occupation ratio of the first modulation unit area in the modulation unit area at the center of each modulation mask is set to a predetermined value. Therefore, the light intensity of the central portion of each unit gradation light irradiated to the workpiece after being modulated by each modulation area of the modulation mask is arbitrarily changed according to the position where each unit gradation light is irradiated. be able to. Thereby, the taper angle of the tapered hole formed by irradiation of each unit gradation light can be made substantially the same regardless of the position where each unit gradation light is irradiated. As a result, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in the workpiece.

  According to the present invention, a plurality of tapered holes having substantially the same taper angle can be simultaneously formed in a workpiece.

FIG. 1 shows a tapered hole forming apparatus according to the present invention. FIG. 2 is a plan view showing a plurality of tapered holes formed in the workpiece in the first embodiment of the present invention. 3A is an enlarged view of the tapered hole in FIG. 2, and FIG. 3B is a longitudinal sectional view showing the tapered hole in FIG. 3A. FIG. 4 is a diagram illustrating a relationship between a tapered hole formed in a workpiece and unit gradation light irradiated on the workpiece. FIG. 5 shows the relationship between the width of the inclined portion of the unit gradation light and the taper angle of the tapered hole formed by the unit gradation light when the light intensity of the central portion of the unit gradation light is constant. FIG. 6A, 6B, and 6C show the case where the light intensity of the central portion of the unit gradation light irradiated to the workpiece and the width of the inclined portion are constant regardless of the position of the tapered hole forming region. The reference figure which shows the taper angle of the taper hole formed in each taper hole formation area. FIGS. 7A and 7B are reference diagrams showing the relationship between the position of the tapered hole forming region and the taper angle of the tapered hole in FIG. 6 as a graph. 8A, 8B, and 8C show the case of the first embodiment of the present invention, in which the width of the inclined portion of the unit gradation light irradiated to the workpiece is a tapered hole forming region. The taper angle of the taper hole formed in each taper hole formation region is shown in the case where the taper hole is changed according to the position of the taper. 9A and 9B are graphs showing the relationship between the position of the tapered hole forming region and the taper angle of the tapered hole in FIG. FIG. 10 is a diagram showing a modification of the embodiment in which the width of the inclined portion of the unit gradation light is changed according to the position of the tapered hole forming region. 11A is a plan view showing the modulation mask according to the first embodiment of the present invention, and FIG. 11B is a cross-sectional view of the modulation mask of FIG. 11A viewed from the XIb-XIb direction. FIG. 12 is a plan view showing a modulation region of the modulation mask according to the first embodiment of the present invention. 13 is an enlarged view of a portion surrounded by a frame XIII in the modulation region shown in FIG. FIG. 14 is a diagram showing a case where the modulation area of FIG. 13 is partitioned into a plurality of virtual modulation unit areas. 15 is a cross-sectional view of the modulation region of FIG. 14 viewed from the XV-XV direction. FIG. 16A is a diagram showing an imaging plane of light emitted from the imaging optical system with respect to the workpiece, FIG. 16B is a diagram showing a point spread function on the imaging plane, and FIG. FIG. 16C is a diagram showing the relationship between the point spread function on the imaging plane and the modulation unit area in the modulation area of the modulation mask, and FIG. 16D shows the light intensity in the point spread function on the imaging plane. The figure which shows a concept. FIG. 17A is a diagram showing a pupil function in the imaging optical system, and FIG. 17B is a diagram showing a point image distribution function in the imaging plane. FIG. 18 is a diagram illustrating an intensity distribution of light irradiated to a workpiece. FIG. 19 is a flowchart showing a procedure for designing a modulation region of a modulation mask in the first embodiment of the present invention. FIG. 20 is a flowchart showing in detail a procedure for designing a modulation area pattern of a modulation mask in the first embodiment of the present invention. 21A (a), (b), and (c) are diagrams showing modulation masks designed so that the width of the modulation mask inclined portion of the corresponding modulation region differs depending on the position of the tapered hole formation region. FIG. 21B is a diagram showing a distribution of the occupation ratio of the first phase modulation unit region in the modulation region shown in FIG. 21A (a). FIGS. 22A and 22B are diagrams showing light intensity distributions of unit tone light that is modulated by the modulation regions shown in FIGS. 21A, 21A, 21B, and 21C and is irradiated on the workpiece. FIG. 23A is a diagram showing the width z of the modulation mask inclined portion in each modulation region in the first embodiment of the present invention, and FIG. 23B is a workpiece that is modulated by each modulation mask inclined portion. The figure which shows the width w of the inclination part of each unit gradation light imaged on the top, FIG.23 (c) is a figure which shows taper angle (phi) of the taper hole formed in a to-be-processed object. FIG. 24A is a diagram showing the width z of the modulation mask inclined portion in each modulation region in the modification of the first embodiment of the present invention, and FIG. 24B is modulated by each modulation mask inclined portion. The figure which shows the width w of the inclination part of each unit gradation light imaged on a to-be-processed object, FIG.24 (c) is a figure which shows taper angle (phi) of the taper hole formed in a to-be-processed object. FIG. 25A is a diagram showing the width z of the modulation mask inclined portion in each modulation region in the modification of the first embodiment of the present invention, and FIG. 25B is modulated by each modulation mask inclined portion. The figure which shows the width w of the inclination part of each unit gradation light imaged on a workpiece, FIG.25 (c) is a figure which shows taper angle (phi) of the taper hole formed in a workpiece. FIG. 26A is a diagram showing a modification of the modulation region of the modulation mask. 26B is an enlarged view showing a portion surrounded by a frame XXVIB in the modulation region shown in FIG. 26A. FIG. 27 is a plan view showing a modulation region of a modulation mask according to the second embodiment of the present invention. 28 is an enlarged view showing a portion surrounded by a frame XXVIII in the modulation region shown in FIG. 29 is a cross-sectional view of the modulation region of FIG. 28 viewed from the XXIX-XXIX direction. FIG. 30 is a flowchart showing a procedure for designing a modulation region of a modulation mask in the second embodiment of the present invention. FIGS. 31A, 31 </ b> B, and 31 </ b> C are diagrams illustrating modulation masks designed such that the width of the modulation mask inclined portion of the corresponding modulation region varies depending on the position of the tapered hole forming region. FIGS. 32A, 32B, and 32C are designed so that the width of the modulation mask inclined portion of the corresponding modulation region differs depending on the position of the tapered hole formation region in the third embodiment of the present invention. FIG. FIGS. 33A and 33B are diagrams showing light intensity distributions of unit gradation light that is modulated by the modulation regions shown in FIGS. 32A, 32B, and 32C and is irradiated on the workpiece. FIG. 34 is a diagram showing the relationship between the light intensity at the center of unit gradation light and the taper angle of the tapered hole formed by the unit gradation light. FIGS. 35A, 35B, and 35C show the case of the fourth embodiment of the present invention, in which the light intensity at the central portion of the unit gradation light irradiated to the workpiece is a tapered hole. In the case of changing according to the position of the region, the taper angle of the tapered hole formed in each tapered hole forming region is shown. 36A and 36B are graphs showing the relationship between the position of the tapered hole forming region and the taper angle of the tapered hole in FIG. FIG. 37 is a diagram showing a modification of the form in which the light intensity at the central portion of the unit gradation light is changed according to the position of the tapered hole forming region. FIG. 38 is a plan view showing a modulation region of a modulation mask according to the fourth embodiment of the present invention. 39 is an enlarged view of a portion surrounded by a frame XXXIX in the modulation region shown in FIG. FIG. 40 is a flowchart showing a procedure for designing a modulation region of a modulation mask in the fourth embodiment of the present invention. 41 (a), 41 (b), and 41 (c) are modulation masks designed so that the occupation ratio of the first phase modulation unit region in the modulation mask central portion of the corresponding modulation region differs depending on the position of the tapered hole forming region. FIG. FIGS. 42A and 42B are diagrams showing light intensity distributions of unit gradation light that is modulated by the modulation regions shown in FIGS. 41A, 41B, and 41C and is irradiated on the workpiece. FIG. 43 is a plan view showing a modulation area of a modulation mask according to the fifth embodiment of the present invention. 44 is an enlarged view showing a portion surrounded by a frame XXXIV in the modulation region shown in FIG. 43. FIG. 45 (a), 45 (b), and 45 (c) are modulation masks designed so that the occupation ratio of the first amplitude modulation unit region in the modulation mask central portion of the corresponding modulation region differs depending on the position of the tapered hole forming region. FIG. 46A is a view showing a modification of a plurality of tapered holes formed in the workpiece, and FIG. 46B is an example of a modulation mask for forming the tapered holes shown in FIG. 46A. FIG. FIG. 47 is a diagram showing a conventional telelaser processing apparatus. FIG. 48 is a diagram showing the relationship between the taper angle and the light intensity of laser light.

First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
First, with reference to FIG. 2, the workpiece 18 irradiated with light from the tapered hole forming apparatus 10 according to the present embodiment and the tapered hole 20 formed in the workpiece 18 will be described.

(Workpiece and tapered hole)
In the present embodiment, the workpiece 18 is irradiated with light from the tapered hole forming apparatus 10 to form a plurality of tapered holes 20 arranged in a line. For example, as shown in FIG. 2, 18 tapered holes 20 (a) to 20 (s) arranged in a line are formed in the workpiece 18. Here, as shown in FIG. 2, among the group of taper holes 20 arranged in a row, the taper hole located at the end of the group is the taper hole 20 (a), and the taper hole located at the center of the group. Is a tapered hole 20 (i). Moreover, the taper hole located in the intermediate part of taper hole 20 (a) and taper hole 20 (i) is taper hole (e). Each tapered hole 20 is formed by irradiating the workpiece 18 with unit gradation light (described later) having a light intensity distribution corresponding to each tapered hole 20 from the tapered hole forming apparatus 10.

  Next, the shape of the taper hole 20 will be described in more detail with reference to FIGS. As shown in FIGS. 3A and 3B, the tapered hole 20 formed in the workpiece 18 has a through portion 20a and a through portion 20a from the proximal end portion 20d of the tapered hole 20 toward the distal end portion 20c. And a tapered portion 20b having a surface inclined so as to be tapered. Here, the inclination angle (taper angle) of the taper portion 20b is an angle φ as shown in FIG. The light from the tapered hole forming device 10 is irradiated from the proximal end portion 20d side of the tapered hole 20.

  The values of the diameter c and the taper angle φ of the tapered hole 20 are not particularly limited, and are appropriately set according to the use of the tapered hole 20. Further, the depth of the tapered hole 20 (the thickness of the workpiece 18) is also appropriately set according to the use of the tapered hole 20.

  As the material of the workpiece 18, a material having good workability and physical stability is used. For example, when the workpiece 18 is processed to produce an inkjet head nozzle, polyimide or the like is used as the workpiece 18. Although not shown, a filler made of silica or calcium carbonate particles may be added to the workpiece 18. By adding such a filler, it is possible to improve the slippage between the workpieces 18, thereby improving the workability when forming the tapered hole 20 in the workpiece 18.

(Unit gradation light)
Next, with reference to FIG. 4, the unit gradation light 50 that is the light emitted from the tapered hole forming device 10 to the workpiece 18 and has a light intensity distribution corresponding to each tapered hole 20 will be described. As shown in FIG. 4, the unit gradation light 50 is positioned at the outer edge of the central portion 51 and the central portion 51 irradiated to the region where the penetrating portion 20 a of the tapered hole 20 is to be formed in the workpiece 18. The inclined portion 52 where the tapered portion 20b of the tapered hole 20 is to be formed in the workpiece 18 and the light intensity decreases toward the outside, and the peripheral portion 53 located at the outer edge of the inclined portion 52. , Including.

  Of these, the light intensity P of the central portion 51 of the unit gradation light 50 is set to a value sufficiently higher than the ablation threshold of the workpiece 18 so as to process the workpiece 18 at a desired speed. Further, the light intensity P ′ of the peripheral portion 53 of the unit gradation light 50 is set such that the region irradiated with the peripheral portion 53 of the unit gradation light 50 in the workpiece 18 is not processed. Is set to a lower value. The light intensity of the inclined portion 52 of the unit gradation light 50 is set so as to monotonously decrease from the light intensity P to the light intensity P ′ as it goes outward.

  In the processing using laser light, a part of the region irradiated with light having the maximum light intensity P in the unit gradation light 50 (center portion 51) is not the through portion 20 a of the tapered hole 20. There may be a taper portion 20b. In the present invention, the central portion 51 of the unit gradation light 50 has the same light intensity P as the light irradiated to the region where the through portion 20a of the tapered hole 20 is to be formed, as shown in FIG. The concept includes light adjacent to the light.

(Basic relationship between taper angle and unit gradation light)
Next, the basic relationship between the taper angle φ of the tapered hole 20 formed in the workpiece 18 and the unit gradation light 50 irradiated to the workpiece 18 will be described. The “basic relationship” is a relationship that is established between the taper angle φ and the unit gradation light 50 when only one tapered hole 20 is formed in the workpiece 18.

  As is apparent from FIG. 4, the region of the tapered hole 20 to which the inclined portion 52 of the unit gradation light 50 is irradiated has a taper having an inclination (gradient) corresponding to the inclination (gradient) of the light intensity in the inclined portion 52. Part 20b. That is, a certain relationship is established between the width w of the inclined portion 52 of the unit gradation light 50 and the taper angle φ of the tapered hole 20. The “width w of the inclined portion 52” is the dimension of the inclined portion 52 in the inclination direction of the light intensity of the inclined portion 52. When the outline of the inclined portion 52 is circular, the inclination direction of the light intensity coincides with the radial direction.

On the other hand, as described above, a certain relationship is also established between the light intensity P of the central portion 51 of the unit gradation light 50 and the taper angle φ of the tapered hole 20 (see FIG. 48A). ). That is, when only one tapered hole 20 is formed in the workpiece 18, the taper angle φ of the tapered hole 20 is the angle φ ₁ calculated based on the width w of the inclined portion 52 of the unit gradation light 50. It is considered that the angle is determined based on both of the angles φ ₂ calculated based on the light intensity P of the central portion 51 of the unit gradation light 50.

  FIG. 5 shows, as a solid line, an example of the relationship between the width w of the inclined portion 52 of the unit gradation light 50 and the taper angle φ of the tapered hole 20 formed by the unit gradation light 50. In FIG. 5, the horizontal axis represents the width w of the inclined portion 52 of the unit gradation light 50, and the vertical axis represents the taper angle φ of the tapered hole 20.

ここでαは、被加工物１８の厚みなどに基づいて決定される定数である。［数１］においては、α×ｗが上述の角度φ_１に相当している。
［数１］に示すように、単位階調光５０の中央部分５１の光強度Ｐ、または単位階調光５０の傾斜部分５２の幅ｗを適切に設定することにより、テーパ穴２０のテーパ角φを任意に調整することが可能であるといえる。 In this case, the value of the intercept, that is, the value of the taper angle φ when the width w of the inclined portion 52 is zero is the angle φ ₂ calculated based on the light intensity P of the central portion 51 of the unit gradation light 50. It has become. Further, as the width w of the inclined portion 52 increases, the taper angle φ of the tapered hole 20 also increases. For example, the relationship between them is expressed by the following [Equation 1].

Here, α is a constant determined based on the thickness of the workpiece 18 and the like. In [Equation 1], α × w corresponds to the angle φ ₁ described above.
As shown in [Equation 1], the taper angle of the tapered hole 20 is set by appropriately setting the light intensity P of the central portion 51 of the unit gradation light 50 or the width w of the inclined portion 52 of the unit gradation light 50. It can be said that φ can be arbitrarily adjusted.

(Taper angle when multiple tapered holes are formed simultaneously)
By the way, when the plurality of tapered holes 20 are simultaneously formed in the workpiece 18, even if the unit gradation lights 50 emitted from the tapered hole forming device 10 are the same light, they are described in the section of the problem. As described above, it is conceivable that the intensity of the unit gradation light 50 when the workpiece 18 is irradiated differs depending on the position of the tapered hole forming region. For example, when the distance between the tapered holes 20 is small, the scattered matter generated in one tapered hole 20 may reach the other tapered hole 20. In this case, among the group of taper holes 20 arranged in a row, the taper hole 20 (i) located at the center of the group is different from the taper hole 20 (a) located at the end of the group. It will be affected more by the scattered matter from 20.

6A, 6B, and 6C show unit gradation lights 50 (a), 50 (e), and 50 (i) in which the light intensity P of the central portion 51 and the width w of the inclined portion 52 are uniform. It is a figure which shows an example of the taper hole 20 (a), 20 (e), and 20 (i) formed in the to-be-processed object 18 when irradiated. In this case, the taper hole 20 (i) in the central part is more affected by scattered matter from the peripheral taper hole 20 than the taper hole 20 (e) in the middle part or the taper hole 20 (a) in the end part. receive. Further, the taper hole 20 (e) at the intermediate part is more influenced by the scattered matter from the peripheral taper hole 20 than the taper hole 20 (a) at the end part. Therefore, the taper angle φ (i) of the central tapered hole 20 (i) is larger than the taper angle φ (e) of the intermediate tapered hole 20 (e). Further, the taper angle φ (e) of the taper hole 20 (e) at the intermediate portion is larger than the taper angle φ (a) of the taper hole 20 (a) at the end portion.
In this case, assuming that the relationship between the taper angle φ (a) in the tapered hole 20 (a) at the end and the width w of the inclined portion 52 is represented by the solid line shown in FIG. Regarding the hole 20 (e), it can be said that the relationship between the taper angle φ (e) and the width w of the inclined portion 52 is shifted to the relationship indicated by the alternate long and short dash line in FIG. Regarding the taper hole 20 (i) at the center, it can be said that the relationship between the taper angle φ (i) and the width w of the inclined portion 52 shifts to the relationship indicated by the two-dot chain line in FIG.

  FIG. 7A is a graph showing the width w of the inclined portion 52 in each unit gradation light 50 in the examples shown in FIGS. 6A, 6B, and 6C. FIG. 6A is a graph showing a taper angle φ of the tapered hole 20 formed in the examples shown in FIGS. As shown in FIG. 7B, the taper angle φ of the tapered hole 20 to be formed differs depending on the position of the tapered hole forming region. Thus, when the light intensity P of the central portion 51 and the width w of the inclined portion 52 are uniform values in each unit gradation light 50, the taper angle φ of the plurality of tapered holes 20 to be formed is made uniform. It can be said that it is difficult.

(Features of this embodiment)
Here, as described above, the taper angle φ of the tapered hole 20 changes in accordance with the light intensity P of the central portion 51 of the unit gradation light 50 or the width w of the inclined portion 52 of the unit gradation light 50. is there. In the present embodiment, it is formed by appropriately adjusting the width w of the inclined portion 52 of the unit gradation light 50 in accordance with the position of the tapered hole forming region using such characteristics of the taper angle φ. The purpose is to make all the taper angles φ of the plurality of tapered holes 20 substantially the same.

  For example, consider a case where the distance between the tapered holes 20 is small. In this case, the taper angle φ of the formed tapered hole 20 deviates from values assumed from the light intensity P of the central portion 51 of the unit gradation light 50 and the width w of the inclined portion 52 of the unit gradation light 50. As a main factor, as shown in FIG. 6, the influence of the scattered matter at the time of ablation can be considered. In this case, the width w of the inclined portion 52 in each unit gradation light 50 is increased toward the end of the taper holes 20 arranged in a row (in other words, the width w is decreased toward the center of the taper holes 20 arranged in a row). It is considered that the taper angle φ of the formed tapered hole 20 can be made substantially the same. That is, in this embodiment, as shown in FIGS. 8A, 8B, and 8C, the width w (of the inclined portion 52 of the unit gradation light 50 irradiated to the tapered hole 20 (a) at the end portion. a) is set to be larger than the width w (e) of the inclined portion 52 of the unit gradation light 50 irradiated to the tapered hole 20 (e) in the intermediate portion. Further, the width w (e) of the inclined portion 52 of the unit gradation light 50 irradiated to the taper hole 20 (e) in the middle portion is set so that the unit gradation light 50 irradiated to the taper hole 20 (i) in the center portion. It is set to be larger than the width w (i) of the inclined portion 52.

  FIG. 9A is a graph showing the width w of the inclined portion 52 in each unit gradation light 50 in the example shown in FIGS. 8A, 8B, and 8C. FIG. 8 is a graph showing the taper angle φ of the tapered hole 20 formed in the examples shown in 8 (a), (b) and (c). Thus, by appropriately adjusting the width w of the inclined portion 52 in each unit gradation light 50 according to the position of the tapered hole forming region, the taper angles φ of the plurality of tapered holes 20 to be formed are made substantially the same. can do. In this case, the adjustment amount of the width w of the inclined portion 52 is appropriately set according to the relationship shown in FIG. For example, as shown in FIG. 5, in the taper hole 20 (i) at the center portion, when the shift amount of the taper angle φ due to the influence of the scattering amount is Δφ (i), the taper hole 20 (a) at the end portion. The width w of the inclined portion 52 is set to be smaller by Δw (i) than

  FIG. 9A shows an example in which the width w of the inclined portion 52 in each unit gradation light 50 is continuously adjusted according to the position of the tapered hole forming region. However, it is not always necessary to continuously adjust the width w of the inclined portion 52, and the width w of the inclined portion 52 may be adjusted discretely as shown in FIG. Even in the case of such discrete adjustment, compared with the case where the width w of the inclined portion 52 is not adjusted, the taper angle φ of the plurality of formed tapered holes 20 can be made uniform, which is advantageous. It is.

(Taper hole forming device)
Next, the tapered hole forming apparatus 10 for generating the unit gradation light 50 in which the width w of the inclined portion 52 can be adjusted according to the position of the tapered hole 20 will be described. First, the entire tapered hole forming apparatus 10 will be described with reference to FIG.

  As shown in FIG. 1, the taper hole forming device 10 is provided on a mounting table 19 on which a workpiece 18 is mounted, a mask illumination system (light source) 11 that emits light, and an exit side of the mask illumination system 11. A modulation mask 21 that modulates and emits light from the mask illumination system 11, and an image of the light modulated by the modulation mask 21 that is provided on the emission side of the modulation mask 21, produces a substantially circular isointensity line. And an imaging optical system 17 that irradiates the workpiece 18 with the light having the same. Among these, the modulation mask 21 and the imaging optical system 17 constitute the light modulation means 15.

  The mask illumination system 11 includes a laser light source 12 that emits pulsed laser light, and an illumination optical system 13 that equalizes the light intensity distribution of the laser light from the laser light source 12. Specifically, the laser light source 12 includes a XeCl excimer laser light source 12 that supplies light having a wavelength of 308 nm. The illumination optical system 13 equalizes the in-plane intensity distribution of light from the laser light source 12 and also uniformizes the incident angle distribution of light incident on the modulation mask 21 from the illumination optical system 13. An eye lens (not shown) and a condenser optical system (not shown) are included.

  As described above, the modulation mask 21 is provided on the emission side of the mask illumination system 11 and modulates and emits the light from the mask illumination system 11. Details will be described later.

  The laser light modulated by the modulation mask 21 is incident on the imaging optical system 17 provided on the emission side of the modulation mask 21. The imaging optical system 17 forms an image of the light modulated by the modulation mask 21 and irradiates the workpiece 18. As shown in FIG. 1, the convex lens 17a, the convex lens 17b, both lenses 17a, And an aperture stop 17c provided between 17b. The size of the aperture 17k of the aperture stop 17c substantially corresponds to the image-side numerical aperture NA of the imaging optical system 17. As will be described later, the size of the opening 17k is set so as to generate a required light intensity distribution in the workpiece 18.

  The laser beam imaged by the imaging optical system 17 is irradiated to the workpiece 18. The workpiece 18 is disposed on a surface optically conjugate with the modulation mask 21, that is, an imaging surface 17 f described later of the imaging optical system 17.

(Modulation mask)
Next, the modulation mask 21 in the present embodiment will be described with reference to FIGS. The modulation mask 21 has a flat plate shape, and is arranged so that the plane portion thereof is orthogonal to the incident and exit directions of the laser beam. Further, as shown in FIG. 11A, the modulation mask 21 is formed so as to fill a plurality of modulation areas (unit modulation means) 22 having a circular outline corresponding to the outline of the tapered hole 20 and between the modulation areas 22. Non-modulation region 23. As shown in FIG. 11A, the plurality of modulation regions 22 have modulation amount distributions 22 (a) each having a modulation amount distribution corresponding to the tapered holes 20 (a) to 20 (s) formed in the workpiece 18. ) To 22 (s).

(Non-modulation area)
The non-modulation region 23 is configured to shield light incident on the non-modulation region 23. Specifically, as shown in FIG. 11B, the non-modulation region 23 includes a modulation mask main body 21a and a light shielding layer 21b provided on the modulation mask main body 21a. The light shielding layer 21b is made of a material that does not transmit light. For this reason, light incident on the non-modulation region 23 of the modulation mask 21 from the illumination optical system 13 is shielded by the light shielding layer 21b without being extracted from the imaging optical system 17 side.

  The light transmittance of the light shielding layer 21 b is appropriately selected so that the intensity of light irradiated to the workpiece 18 through the non-modulation region 23 does not exceed the ablation threshold of the workpiece 18. For example, the light transmittance of the light shielding layer 21b is 0.00001 or less, preferably 0. As a material of the light shielding layer 21b, a material capable of realizing a desired light transmittance can be appropriately used. For example, various light shielding materials such as chromium, aluminum, silicon oxide, or a dielectric multilayer film are used. Can do.

(Modulation area)
Next, the modulation region 22 of the modulation mask 21 will be described in detail with reference to FIGS. Each of the modulation regions 22 (a) to 22 (s) is different only in the width of a modulation mask inclined portion described later, and the other structures are substantially the same.

  As shown in FIG. 12, the modulation region 22 includes a modulation mask central portion 34 that modulates light applied to a region where the through-hole 20 a of the tapered hole 20 is formed in the workpiece 18, and a modulation mask central portion 34. A modulation mask inclined portion 32 that modulates light irradiated on a region of the workpiece 18 where the tapered portion 20b of the tapered hole 20 is formed on the workpiece 18, and a peripheral edge of the modulation mask positioned on the outer edge of the modulation mask inclined portion 32 Part 33.

(Modulation mask slope)
First, the modulation mask inclined portion 32 will be described. As shown in FIG. 12, the modulation mask inclined section 32 of the modulation region 22 has a number of first phase modulation unit regions (first modulation unit regions) that modulate light with a first phase modulation amount (first modulation amount). ) 25a and a second phase modulation unit region (second modulation unit region) 25b that is formed to fill each first phase modulation unit region 25a and modulates light with a second phase modulation amount (second modulation amount). And have. When the horizontal direction in FIG. 12 is the x direction and the direction is orthogonal to the x direction, and the vertical direction in FIG. 12 is the y direction, each first phase modulation unit region 25a has an x direction as shown in FIG. A pair of x direction side edges 28a extending in the direction and a pair of y direction side edges 28b extending in the y direction are provided. As will be described later, the side edges constituting all the first phase modulation unit regions 25a are extended by the side edges (x direction side edges 28a or y direction side edges 28b) extending only in either the x direction or the y direction. By configuring, the modulation region 22 can be easily manufactured.

  Here, as shown in FIGS. 12 and 13, the first phase modulation unit regions 25 a are periodically arranged on a predetermined circumferential line 27. The areas of the first phase modulation unit regions 25a arranged on the same circumferential line 27 are the same. Furthermore, the area of the first phase modulation unit region 25a monotonously increases toward the outside in the radial direction of the modulation mask inclined portion 32 of the modulation region 22 (outward of the modulation region 22). For this reason, the occupation ratio of the first phase modulation unit region 25a monotonously increases toward the outside of the modulation region 22. Here, the occupation ratio of the first phase modulation unit region 25a means that the modulation mask inclined portion 32 of the modulation region 22 has a predetermined area and each has one first phase modulation unit region 25a, as will be described later. It is the area ratio of the first phase modulation unit region 25a with respect to the area of the modulation unit region when partitioned into a plurality of modulation unit regions.

  In the present invention, the region where the occupation ratio of the first phase modulation unit region 25a changes along the radial direction is the modulation mask inclined portion 32. More specifically, the occupancy value of the first phase modulation unit region 25a is equal to the occupancy value of the first phase modulation unit region in the modulation mask peripheral portion 33 and the first phase modulation unit in the modulation mask central portion 34. A region composed of the modulation unit region having a value between the region occupancy rate and the value of the region occupancy is the modulation mask inclined portion 32.

  Next, a specific arrangement pattern of each first phase modulation unit region 25a will be described. As shown in FIG. 12, a plurality of virtual circumferential direction lines 27 provided in an annular shape in the modulation mask inclined portion 32 are considered. In this case, each first phase modulation unit region 25 a is provided along a circumferential line 27. Specifically, each first phase modulation unit region 25 a is arranged such that its center is located on the circumferential line 27.

With reference to FIG. 13, the arrangement pattern of each first phase modulation unit region 25a will be described in more detail. FIG. 13 is an enlarged view of a portion surrounded by a frame XIII in the modulation region 22 of FIG. As shown in FIG. 13, the radial distance L ₁ between the circumferential line 27 of the annular first phase modulation unit region 25a is disposed, it is substantially constant. In addition, as shown in FIG. 13, the circumferential distance L ₂ between the centers of the two first phase modulation unit region 25a adjacent on the same circumferential line 27, it is substantially constant. Further, as shown in FIG. 13, not only between the first phase modulation unit regions 25a arranged on the same circumferential line 27, but also the first phase modulation arranged on all the same circumferential lines 27. in between the unit area 25a, the circumferential distance L ₂ between the centers it is substantially constant. Thus, the first phase modulation unit regions 25a can be arranged so as to be periodically arranged on the predetermined circumferential direction line 27.

Next, a description will be given radial distance L ₁ and the circumferential distance L ₂ above. The radius R of the point image distribution range of the imaging optical system 17 is defined as R = 0.61λ / NA using the center wavelength λ of light from the laser light source 12 and the numerical aperture NA on the exit side of the imaging optical system 17. when the radial distance L ₁ and to at least one of the circumferential distance L ₂ distance in terms of imaging surface 17f of the respective image forming optical system 17 is smaller than R, the radial distance L ₁ and circle circumferential distance L ₂ is set. Here, “the distance obtained by converting the radial distance L ₁ and the circumferential distance L ₂ into the imaging surface 17 f of the imaging optical system 17” means the radial distance L ₁ and the circumferential distance in the modulation mask 21. It is a value obtained by multiplying L ₂ by the magnification of the imaging optical system 17.

Next, the occupation ratio of the first phase modulation unit region 25a will be described with reference to FIG. First, as shown by a dotted line in FIG. 14, the modulation mask inclined portion 32 is partitioned into a plurality of modulation unit regions 24e each having a predetermined area and each including one first phase modulation unit region 25a.
The dotted lines in FIG. 14 that define the modulation unit region 24 e are, for example, a circumferential line extending along an intermediate point between two adjacent circumferential lines 27 and two adjacent lines on the circumferential line 27. And a radial line extending perpendicular to a line connecting the centers of the first phase modulation unit regions 25a. By drawing the dotted line shown in FIG. 14, the modulation mask inclined portion 32 is partitioned into a plurality of modulation unit regions 24e each having a predetermined area and each including one first phase modulation unit region 25a. be able to. Here, when each modulation unit region 24e is approximated by a rectangle, the length of the rectangle is approximately equal to L ₁ and L ₂ . Therefore, the modulation unit conversion region obtained by converting each modulation unit region 24e to the image formation surface 17f of the image formation optical system 17 is smaller than the radius R of the point image distribution range of the image formation optical system 17 in at least one direction. ing.

  As shown in FIG. 14, each modulation unit region 24e is composed of one first phase modulation unit region 25a and a second phase modulation unit region 25b surrounding the first phase modulation unit region 25a. In the modulation mask inclined portion 32 shown in FIGS. 12 to 14, the area of each first phase modulation unit region 25a monotonously increases toward the outside in the radial direction (outside the modulation region 22). For this reason, the occupation ratio of the first phase modulation unit region 25 a monotonously increases toward the outside of the modulation region 22. As will be described later, the light phase-modulated and emitted by the modulation mask inclined portion 32 of the modulation region 22 of the modulation mask 21 is projected onto the imaging surface of the imaging optical system 17 on the first phase modulation unit in each modulation unit region 24e. A light intensity distribution based on the occupation ratio of the region 25a is generated. For this reason, the light phase-modulated and emitted by the modulation mask tilting part 32 generates a light intensity distribution that decreases toward the outside on the imaging surface of the imaging optical system 17.

  In such a modulation mask inclined portion 32, the width is represented by the symbol z (see FIGS. 12 and 13). Here, the “width z of the modulation mask inclined portion 32” is the width of the modulation mask inclined portion 32 in the direction in which the occupation ratio of the first phase modulation unit region 25a changes (inclination direction of the occupation ratio). When the contour of the modulation mask inclined portion 32 is circular, the direction in which the occupation ratio changes coincides with the radial direction.

  Next, the structure of the first phase modulation unit region 25a and the second phase modulation unit region 25b of the modulation mask inclined part 32 will be described with reference to FIG. FIG. 15 is a view showing a cross section of the modulation region 22 of FIG. 14 viewed from the XV-XV direction. As shown in FIG. 15, in the modulation mask inclined part 32, the modulation mask main body part 21a has irregularities on the surface thereof. The modulation mask body 21a is made of a material that transmits light, for example, quartz glass having a refractive index n.

  As shown in FIG. 15, the height of the modulation mask main body 21a in the region corresponding to the first phase modulation unit region 25a is different from the height of the modulation mask main body 21a in the region corresponding to the second phase modulation unit region 25b. ing. Here, when the height difference is Δh and the refractive index of air is 1, the optical distance from the incident surface to the output surface of the modulation mask 21 in the first phase modulation unit region 25a in the modulation mask inclined portion 32, The difference from the optical distance from the incident surface to the exit surface of the modulation mask 21 in the second phase modulation unit region 25b is Δh × (n−1).

  In the present embodiment, the optical distance difference Δh × (n−1) is an odd multiple of {λ / 2}, that is, the phase modulation amount and the second phase in the first phase modulation unit region 25a. Δh is set so that the difference from the phase modulation amount in the modulation unit region 25b is an odd multiple of 180 degrees. For example, when the center wavelength λ of the laser light emitted from the mask illumination system 11 is 308 nm and the refractive index n of quartz glass forming the modulation mask main body 21a is 1.49, the modulation mask main body so that Δh is 317 nm. The uneven shape of the surface of 21a is designed.

(Modulation mask edge)
Next, the modulation mask peripheral portion 33 will be described. As shown in FIG. 12, the modulation mask peripheral portion 33 is formed between a large number of first phase modulation unit regions 45a that modulate light with a first phase modulation amount and each of the first phase modulation unit regions 45a. And a plurality of second phase modulation unit regions 45b for modulating the second phase modulation amount with the second phase modulation amount. As shown in FIG. 12, each of the first phase modulation unit region 45a and the second phase modulation unit region 45b has a ring shape. The first phase modulation unit region 45a and the second phase modulation unit region 45b are different only in the shape and arrangement pattern when the modulation region 22 is shown in a plan view. The first phase modulation unit region 25a and the second phase modulation unit region 25b are substantially the same.

  The shape and arrangement pattern of the first phase modulation unit region 45a will be described in more detail. As shown in FIG. 12, the first phase modulation unit regions 45a are arranged in multiple rows in the radial direction and are formed to extend in an annular shape. Specifically, each first phase modulation unit region 45a is formed so as to evenly cover a plurality of virtual circumferential lines 27 virtually provided in the modulation mask peripheral portion 33 in the radial direction. . Thereby, the occupation ratio (described later) of the first phase modulation unit region 45a when viewed along the circumferential line 27 can be made substantially constant.

Next, the arrangement pattern of the first phase modulation unit region 45a will be described in more detail with reference to FIG. As shown in FIG. 13, the radial distance L ₁ (the radial distance between two adjacent circumferential lines 27) between two adjacent first phase modulation unit regions 45a is substantially constant. Here, the radius R of the point image distribution range of the imaging optical system 17 is set to R = 0.61λ / using the center wavelength λ of the light from the laser light source 12 and the numerical aperture NA on the exit side of the imaging optical system 17. when defined as NA, a distance obtained by converting the radial distance L ₁ of the two first phase modulation unit region 45a adjacent to the imaging surface 17f of the respective image forming optical system 17, the point spread in the imaging optical system 17 It is smaller than the radius R of the range. Here, “a distance obtained by converting the radial distance L ₁ into the imaging surface 17 f of the imaging optical system 17” is a value obtained by multiplying the radial distance L ₁ in the modulation mask 21 by the magnification of the imaging optical system 17. That is.

Next, the occupation ratio of the first phase modulation unit region 45a will be described with reference to FIG. First, as shown by a dotted line in FIG. 14, the modulation mask peripheral portion 33 is partitioned into a plurality of modulation unit regions 24 e each having a predetermined area and each crossing one first phase modulation unit region 45 a in the radial direction. .
The dotted line in FIG. 14 is, for example, from a dotted line drawn so that the area and shape of the modulation unit region 24e in the modulation mask inclined portion 32 and the area and shape of the modulation unit region 24e in the modulation mask peripheral portion 33 are substantially the same. It has become. By drawing the dotted line shown in FIG. 14 in this way, the modulation mask peripheral portion 33 has a predetermined area and a plurality of modulation unit regions 24e each crossing one first phase modulation unit region 45a in the radial direction. Can be partitioned. In this case, the occupation ratio of the first phase modulation unit region 45a is defined as the area ratio of the first phase modulation unit region 45a in each modulation unit region 24e.

Here, when approximating the respective modulation unit area 24e rectangular, the length of one side of the rectangle is approximately equal to L _1. Therefore, the modulation unit conversion region obtained by converting each modulation unit region 24e to the image formation surface 17f of the image formation optical system 17 is smaller than the radius R of the point image distribution range of the image formation optical system 17 in at least one direction. ing. For this reason, the light that is modulated by the peripheral edge portion 33 of the modulation mask and is applied to the workpiece 18 has an intensity distribution based on the occupation ratio of the first phase modulation unit region 45a. Here, in the modulation mask peripheral portion 33, the occupation ratio of the first phase modulation unit region 45a is about 0.5 over the entire region. For this reason, as will be described later, the light that has been phase-modulated by the modulation mask peripheral portion 33 and emitted is generated with a substantially zero light intensity distribution on the imaging surface of the imaging optical system 17.

(Center of modulation mask)
Next, the modulation mask center part 34 will be described. The modulation mask central portion 34 modulates light irradiated to a region of the workpiece 18 where the through portion 20a of the tapered hole 20 is formed. As shown in FIG. 12, the modulation mask central portion 34 is composed only of the second phase modulation unit region 25b that modulates light with the second phase modulation amount. Therefore, the occupation ratio of the first phase modulation unit region 25a in the modulation mask central portion 34 is zero.

(Generation principle of light intensity distribution)
Next, referring to FIG. 16 and FIG. 17, the light phase-modulated by the modulation region 22 of the modulation mask 21 and emitted is incident on the imaging surface of the imaging optical system 17 in the first phase in each modulation unit region 24 e. The principle of generating a light intensity distribution based on the occupation ratio of the modulation unit regions 25a and 45a will be described.

ここで、ｄはパルス状のレーザ光を被加工物１８に一回照射したときのアブレーションレート、αは被加工物１８の光吸収率、Ｉはレーザ光のエネルギー密度（光強度）、Ｉ_ｔｈは被加工物１８におけるアブレーション発生閾値を示す。 First, the relationship between the intensity of laser light and the ablation depth will be described. In general, the relational expression of [Equation 2] holds between the intensity of the laser beam irradiated to the workpiece 18 and the depth (ablation rate) of the portion of the workpiece 18 that is removed by ablation (ablation rate). It has been known.

Here, d is the ablation rate when the workpiece 18 is irradiated with pulsed laser light once, α is the light absorption rate of the workpiece 18, I is the energy density (light intensity) of the laser beam, and I _th. Indicates the ablation occurrence threshold in the workpiece 18.

  As is apparent from [Equation 2], the ablation rate d depends on the energy density I of the laser beam. In addition, when laser light irradiation is repeated a plurality of times, it is known that the total depth of the portion of the workpiece 18 that is removed by laser light irradiation is proportional to the number of times of laser light irradiation. Therefore, by arbitrarily setting the energy density I of the laser light irradiated to the workpiece 18 according to the location of the workpiece 18, the workpiece 18 can be processed into an arbitrary shape.

  Next, the relationship between the object plane (modulation mask 21) and the imaging plane 17f (workpiece 18) in the imaging optical system 17 will be described.

ここで、＊はコンボリューション（たたみ込み積分）を表す。 The relationship between the object plane distribution and the imaging plane distribution in the imaging optical system 17 can be generally handled by Fourier imaging theory. When the coherence factor is about 0.5 or less, it can be approximated as coherent imaging. In this case, the complex amplitude distribution U (x, y) on the imaging plane, that is, the workpiece 18 is a complex amplitude transmittance distribution T (x, y) of the modulation mask 21 as shown in [Equation 3] below. And the convolution integral of the complex amplitude point spread function ASF (x, y) of the imaging optical system 17

Here, * represents convolution (convolution integration).

ここで、ｒは以下の［数５］により表される関数である。また、Ｊ_１はベッセル関数、λは光の波長、ＮＡは結像光学系１７の結像側開口数を表す。

The above point spread function ASF (x, y) is given by Fourier transform of the pupil function of the imaging optical system 17. In this case, when the pupil is circular and has no aberration, a well-known Airy pattern is obtained ([Equation 4]).

Here, r is a function represented by the following [Equation 5]. J ₁ is a Bessel function, λ is the wavelength of light, and NA is the imaging-side numerical aperture of the imaging optical system 17.

  Next, the point spread function ASF (x, y) of the imaging optical system 17 will be described. As described above, the imaging surface 17f, that is, the complex amplitude distribution U (x, y) of the workpiece 18 has the complex amplitude transmittance distribution T (x, y) of the modulation mask 21 and the point of the imaging optical system 17. It is given by the convolution integral with the image distribution function ASF (x, y). Here, when the point spread function ASF (x, y) is approximated by the cylindrical shape 17e as described above, the complex amplitude transmission of the modulation mask 21 in the circular point spread range 17l shown in FIG. The result of integrating the rate with a uniform weight is the complex amplitude in the image plane 17f. Then, the square of the absolute value of the complex amplitude on the image plane 17f is the intensity of the laser light irradiated on the workpiece 18.

  The integration of the complex amplitude transmittance of the modulation mask 21 in the point image distribution range 17l can be considered as the sum of a plurality of vectors 17h representing the complex amplitude transmittance in the unit circle 17g, as shown in FIG. it can. The light irradiation intensity at the corresponding position on the workpiece 18 is calculated by squaring the absolute value of the sum of the plurality of vectors 17h.

  FIGS. 17A and 17B show the relationship between the pupil function and the point spread function ASF (x, y) in the imaging optical system 17. In general, the point spread function ASF (x, y) shown in FIG. 17B is given by Fourier transform of the pupil function shown in FIG. When the imaging optical system 17 has a uniform circular pupil and no aberration, the point spread function ASF (x, y) is expressed by [Expression 4] as described above. However, this does not apply when there is aberration in the imaging optical system 17 or when the imaging optical system 17 has a pupil function other than the uniform circular pupil.

ここで前述の点像分布範囲１７ｌは、図１６（ｂ）または図１７（ｂ）に示すように、点像分布関数ＡＳＦ（ｘ，ｙ）が最初に０となるまでの円形状の中央領域、即ちエアリーディスク内側を意味することになる。なお本実施の形態において、例えばレーザ光の波長λ＝３０８ｎｍ、結像光学系１７の結像側の開口数ＮＡ＝０．１５とすると、Ｒ＝１．２５μｍとなる。 When the pupil function in the imaging optical system 17 is a uniform circular pupil and there is no aberration in the imaging optical system 17, a central region (ie, Airy) until the point spread function ASF (x, y) first becomes zero. The radius R of the disk is given by [Equation 6] below.

Here, the point image distribution range 17l is a circular central region until the point image distribution function ASF (x, y) first becomes 0, as shown in FIG. 16 (b) or FIG. 17 (b). That is, it means the inside of the Airy disk. In this embodiment, for example, assuming that the wavelength λ of the laser beam is 308 nm and the numerical aperture NA on the imaging side of the imaging optical system 17 is 0.15, R = 1.25 μm.

  As is apparent from FIGS. 16A to 16D, when a plurality of modulation unit regions 24e are included in a circle optically corresponding to the point image distribution range 17l of the imaging optical system 17, that is, When there are a plurality of vectors 17h in the unit circle 17g shown in FIG. 16D, the amplitude of light is represented by the sum of the plurality of vectors 17h. Therefore, by adjusting the complex amplitude transmittance in each modulation unit region 24e, the light intensity distribution can be controlled analytically and according to a simple calculation.

  As apparent from the above description, in order to freely control the intensity distribution of the light that has passed through the modulation region 22 of the modulation mask 21, as shown in FIG. 16C, the modulation unit region 24e of the modulation region 22 is used. Is preferably optically smaller than the radius R of the point image distribution range 17 l of the imaging optical system 17. That is, the modulation unit conversion region obtained by converting the modulation unit region 24e of the modulation region 22 into the imaging surface 17f of the imaging optical system 17 is smaller than the radius R of the point image distribution range of the imaging optical system 17 in at least one direction. It is preferable.

Here, for example, when the magnification of the imaging optical system 17 is 1/5, the modulation unit conversion region obtained by converting the modulation unit region 24e into the imaging surface 17f of the imaging optical system 17 is the imaging optical system 17. The modulation region 22 of the modulation mask 21 is designed so as to be smaller in at least one direction than the radius R of the point image distribution range of R = 1.25 μm. That is, the modulation region 22 by such a satisfying modulation unit area 24e is to be divided, radial distance L ₁ and the circumferential distance L ₂ described above is set.
In the present embodiment, the radial distance L ₁ and the circumferential distance L ₂ above are both set to 5 [mu] m. That is, each of the first phase modulation unit region 25a is the radial distance L ₁ and the circumferential distance L ₂ above are arranged so that both the 5 [mu] m. Further, each of the first phase modulation unit region 45a is arranged so that the radial distance L ₁ described above is 5 [mu] m. In this case, when the modulation unit region 24e shown in FIG. 14 is approximated by a square, one side of the rectangle is about 5 μm. In this case, the modulation unit conversion region obtained by converting the modulation unit region 24e formed of a square of 5 μm × 5 μm into the imaging surface 17f of the imaging optical system 17 is (5 μm × 5 μm) × 1/5, that is, a square of 1 μm × 1 μm. The radius R of the point image distribution range of the imaging optical system 17 is smaller than 1.25 μm.

［数７］中、Ｃは定数であり、積分は点（ｘ,ｙ）を中心とする半径Ｒの内側の積分を示している。 Next, the relationship between the modulation area of the modulation mask 21 and the intensity I of the laser beam will be described. When the point spread function ASF (x, y) is approximated by a function having a constant value 1 inside the Airy disk and 0 outside the Airy disk, [Equation 3] is approximated by integration inside the Airy disk ([Equation 7] ]).

In [Equation 7], C is a constant, and the integral indicates the integral inside the radius R with the point (x, y) as the center.

  Here, the operation of the modulation unit region 24e will be considered again. The modulation unit region 24e may be covered with a region having the same shape and size, or may vary from place to place. Here, when the areas of the plurality of modulation unit regions 24e within the range of the Airy disk are equal and the structure of the complex amplitude transmittance does not change greatly between them, the integration range of [Equation 6] is set to the inside of the Airy disk. To the inside of the modulation unit region 24e including (x, y).

ここで、Δｈは変調領域２２に形成された凹部の深さ（凸部の高さ）を表している。 Next, a method for deriving the light intensity distribution of light that has passed through the modulation region 22 of the modulation mask 21 will be described with reference to FIGS. 16 and 17. As described above, the modulation region 22 is formed of quartz glass having a refractive index n and having an uneven surface. In this case, when the laser beam passes through the concave portion (convex portion), the wavefront is shifted by the difference between the refractive index n of quartz glass and the refractive index 1 of air, and phase modulation is performed. The phase modulation amount θ at this time is expressed by the following [Equation 8].

Here, Δh represents the depth of the concave portion formed in the modulation region 22 (height of the convex portion).

ここで、Σは当該変調単位領域２４ｅにおけるすべての位相変調単位領域に関する和を表している。 Here, it is assumed that the depth of the concave portion (height of the convex portion) Δh is discrete, that is, multi-stage processed, and the area ratio and phase of the k-th phase modulation unit region within a certain modulation unit region 24e. The modulation amounts are represented as D _{p, k} and θ _k , respectively. In this case, based on the above [Equation 7], the complex amplitude transmittance U and the intensity I of the laser beam on the imaging surface 17f of the imaging optical system 17 corresponding to the modulation unit region 24e are obtained as follows. .

Here, Σ represents the sum related to all the phase modulation unit regions in the modulation unit region 24e.

ここでＤ_ｐは、各変調単位領域２４ｅにおける第１位相変調単位領域の面積率を表している。この式をＤ_ｐに関して解くと、以下の［数１２］が得られる。

本実施の形態においては、上述のように、第１位相変調単位領域における位相変調量と第２位相変調単位領域における位相変調量との差が１８０度の奇数倍となるよう、Δｈが設定されている。すなわち、θ＝１８０度となっている。この場合、上記の［数１１］および［数１２］が以下の［数１３］および［数１４］のように表される。

For the sake of simplicity, the modulation area 22 of the modulation mask 21 includes a first phase modulation unit area (first phase modulation unit areas 25a and 45a) and a second phase modulation unit area (second phase modulation unit areas 25b and 45b). Consider the case of two types. When the phase of the laser beam modulated by the first phase modulation unit region and the second phase modulation unit region is expressed as θ ₁ (= θ) and θ ₂ (= 0), respectively, the intensity I of the laser beam is expressed by the following [number 11].

Here D _p represents the area ratio of the first phase modulation unit area in each modulation unit area 24e. Solving this equation with respect to D _p yields [Equation 12] below.

In the present embodiment, as described above, Δh is set so that the difference between the phase modulation amount in the first phase modulation unit region and the phase modulation amount in the second phase modulation unit region is an odd multiple of 180 degrees. ing. That is, θ = 180 degrees. In this case, the above [Expression 11] and [Expression 12] are expressed as [Expression 13] and [Expression 14] below.

  As described above, the intensity distribution I of the laser beam applied to the workpiece 18 based on [Equation 2] according to the size of the tapered hole 20 formed in the workpiece 18 and the inclination angle of the tapered portion 20b. Can be set. Furthermore, the area ratio of the first phase modulation unit regions 25a and 45a in each modulation unit region 24e can be set according to [Equation 14] so that the desired laser light intensity distribution I can be obtained. That is, by preparing the predetermined modulation mask 21, it is possible to form the tapered hole 20 having a desired size, inclination angle, and the like in the workpiece 18.

FIG. 18 shows an example of the light intensity distribution of the unit gradation light 50 emitted from the imaging optical system 17 and imaged on the workpiece 18 after passing through the modulation region 22 of the modulation mask 21 according to the present embodiment. Show.
As described above, the occupation ratio of the first phase modulation unit region 25a in the modulation mask central portion 34 is zero. For this reason, as shown in FIG. 18, as the light corresponding to the modulation mask central portion 34, the central portion 51 of the unit gradation light 50 having the maximum light intensity P is imaged on the workpiece 18.
Further, as described above, the occupation ratio of the first phase modulation ring region 45 a in the modulation mask peripheral portion 33 is about 0.5 over the entire area of the modulation mask peripheral portion 33. Therefore, as shown in FIG. 18, as the light corresponding to the modulation mask peripheral portion 33, the peripheral portion 53 of the unit gradation light 50 having almost zero light intensity P ′ is imaged on the workpiece 18. .
Further, as described above, the occupation ratio of the first phase modulation unit region 25a in the modulation mask inclined part 32 monotonously increases toward the outer side in the radial direction of the modulation mask inclined part 32 (outward of the modulation mask inclined part 32). doing. Further, the occupation ratio of the first phase modulation unit region 25a in the modulation mask inclined part 32 is smaller than 0.5. Therefore, the difference between the occupation ratio of the first phase modulation unit region 25a and the occupation ratio of the second phase modulation unit region 25b in the modulation mask inclined part 32 monotonously decreases toward the outside of the modulation mask inclined part 32. Yes. For this reason, as shown in FIG. 18, as the light corresponding to the modulation mask inclined portion 32, the inclined portion 52 of the unit gradation light 50 whose intensity monotonously decreases from the light intensity P to the light intensity P ′ as it goes outward. Is imaged. In this case, the width w of the inclined portion 52 can be adjusted by appropriately setting the width z of the modulation mask inclined portion 32.

  Next, the operation of the present embodiment having such a configuration will be described. Here, a method of forming 18 tapered holes 20 having the same taper angle φ on the workpiece 18 using the tapered hole forming apparatus 10 provided with the modulation mask 21 will be described.

(Modulation mask design procedure)
First, the design procedure of the modulation mask 21 will be described. First, a design procedure of the modulation region 22 of the modulation mask 21 will be described with reference to FIGS. 19 and 20. FIG. 19 is a flowchart showing a procedure for designing the modulation region 22 of the modulation mask 21, and FIG. 20 is a flowchart showing in detail a procedure for designing the pattern of the modulation region 22 in the design of the modulation region 22. is there.

(Modulation area design procedure)
(A) First, information (position (x, y), radius, depth, taper angle φ, etc.) regarding each tapered hole 20 formed in the workpiece 18 is input (S101). For example, 11 degrees is input as the taper angle φ. In addition, 30 μm and 50 μm are input as the radius and depth of the tapered hole 20.
(B) Next, the laser beam irradiation frequency m is input (S102). For example, 150 times is input as the number of times of irradiation m.
(C) Thereafter, based on the depth of the tapered hole 20 and the number of times of laser light irradiation, the light intensity P of the central portion 51 of the unit gradation light 50 irradiated to the workpiece 18 is calculated (S103). For example, 1000 mJ / cm ² is calculated as the light intensity P of the central portion 51.
(D) Next, based on a reference FIG. 48 (a), calculates an angle phi ₂ above (S104). Then, based on the input taper angle φ and the calculated angle φ ₂ , an angle φ ₁ to be formed due to the width w of the inclined portion 52 of the unit gradation light 50 is calculated (S 105). .
(E) Next, based on the calculated angle φ ₁ and the depth of the tapered hole 20, the width w of the inclined portion 52 of the unit gradation light 50 to be irradiated on the workpiece 18 is calculated. At this time, based on the relationship of FIG. 5, the value of the width w of the inclined portion 52 of the unit gradation light 50 is corrected according to the position where the tapered hole 20 is to be formed (S106). For example, in the case of ablation, when it is anticipated that a large amount of scattered objects will pass between the tapered holes 20, the width w ( The width w is corrected so that a) is larger than the width w (i) of the inclined portion 52 of the unit gradation light 50 irradiated to the central tapered hole 20 (i). A specific correction amount for the width w is determined based on past experimental results. For example, the width w (a), w (e) of the inclined portion 52 of the unit gradation light 50 irradiated to the tapered holes 20 (a), 20 (e), and 20 (i) at the end, middle, and center. ) And w (i) are determined to be 4 μm, 3 μm and 2 μm, respectively.
(F) Next, based on the calculated width w and the position (x, y) and radius of the tapered hole 20, a desired ablation rate d (x, y) in the workpiece 18 is calculated (S107). .
(G) Thereafter, based on d (x, y), the light intensity distribution I (x, y) of the light irradiated on the workpiece 18 is calculated (S108). In the light intensity distribution I (x, y), the light intensity P calculated in S103 described above is used as the light intensity of the region corresponding to the central portion 51 of the unit gradation light 50.
(H) Next, based on the intensity distribution I (x, y) of the laser beam and [Equation 14], the occupancy rates of the first phase modulation unit regions 25a and 45a in each modulation region 22 of the modulation mask 21 (each modulation) The area ratio D _p of the first phase modulation unit regions 25a and 45a in the unit region 24e is calculated (S109). Area ratio D _p is calculated for each was partitioned modulation unit area 24e as a unit area.
The (re) Finally, based on the calculated area ratio _{D p,} the first phase modulation unit areas 25a in each of the modulation area 22 in the modulation mask 21, the arrangement pattern of 45a is determined (S110).

  Next, refer to FIG. 20 for the procedure for designing the arrangement pattern of the first phase modulation unit regions 25a and 45a in each modulation region 22, especially the arrangement pattern of the first phase modulation unit region 25a of the modulation mask inclined portion 32. And will be described in detail.

(J) First, enter the radial distance _{L 1} described above (S121), then inputs the circumferential distance _{L 2} above (S122). In this case, as the distance in terms of imaging surface 17f of the radial distance L ₁ and the circumferential distance L ₂ each imaging optical system 17 is smaller than R, the radial distance L ₁ and the circumferential distance L ₂ is set.
(Le) Next, the respective modulation mask inclined portion 32, a virtual circumferential line 27 of the plurality of annular, is provided so that the radial distance between the circumferential line 27 adjacent is L ₁ (S123). Thereafter, on the circumferential line 27, a plurality of first phase modulation unit region 25a is, the circumferential distance between the centers between the first phase modulation unit region 25a adjacent are arranged so as to be L ₂ ( S124).
(E) Next, the modulation mask inclined portion 32 is partitioned into a plurality of modulation unit regions 24e each having a predetermined area and each including one first phase modulation unit region 25a (S125). In this case, for example, as described above, a circumferential line extending along an intermediate point between two adjacent circumferential lines 27 and two first phase modulation unit regions adjacent on the circumferential line 27 The modulation mask inclined portion 32 is partitioned into a plurality of modulation unit regions 24e by drawing a radial line extending perpendicular to a line connecting the centers of 25a.
(Wa) Next, the area ratio _{D p} calculated in S109, based on the area of each modulation unit area 24e, the area of the first phase modulation unit areas 25a in each of the modulation unit area 24e is determined (S126 ).
In this manner, the arrangement pattern of the first phase modulation unit region 25a is designed in each modulation mask inclined portion 32.
A method of arranging the first phase modulation unit region 45a in the modulation mask periphery 33 is the point which becomes unnecessary is designed in the circumferential direction a distance L ₂ in S121~S126 above differ only, the other points This is substantially the same as the method of disposing the first phase modulation unit region 25a in each modulation mask inclined portion 32.

  Specific modulation regions 22 designed as described above are shown in FIGS. 21A (a) (b) (c). FIGS. 21A (a), 21 (b), and 21 (c) show the modulation region 22 (a) at the end, the modulation region 22 (e) at the middle, and the modulation region 22 (i) at the center.

  As described above, the width w (a) of the inclined portion 52 of the unit gradation light 50 irradiated to the tapered holes 20 (a), 20 (e), and 20 (i) at the end portion, the intermediate portion, and the central portion, w (e) and w (i) are determined to be 4 μm, 3 μm and 2 μm, respectively. In this case, in the corresponding modulation regions 22 (a), 22 (e) and 22 (i), the widths z (a) and z of the modulation mask inclined portions 32 (a), 32 (e) and 32 (i) (E) and z (i) are 15 μm (3 μm × (reciprocal of magnification 1/5 of imaging optical system 17), 10 μm (2 μm × (reciprocal of magnification 1/5 of imaging optical system 17) and 5 μm, respectively. 1 μm × (the reciprocal of the magnification 1/5 of the imaging optical system 17) Here, as shown in FIGS. 21A (a) (b) (c), the modulation mask inclined portions 32 (a), 32 are provided. The widths z (a), z (e), and z (i) in (e) and 32 (i) are aligned in the width direction of each modulation mask inclined portion 32 (a), 32 (e), and 32 (i). Adjustment is made by increasing or decreasing the number of modulation unit regions 24e.

The width w (a) of the inclined portion 52 is 4 μm, and the width z (a) of the modulation mask inclined portion 32 (a) is 15 μm (3 μm × (the reciprocal of the magnification 1/5 of the imaging optical system 17)). explain.
FIG. 21B is a diagram showing a distribution of the occupation ratio of the first phase modulation unit region in the modulation region 22 (a) shown in FIG. 21A (a). As shown in FIG. 21B, the occupation ratio of the first phase modulation unit region 45a in the modulation mask peripheral portion 33 is a substantially constant value (about 0.5), and the first phase in the modulation mask central portion 34 is obtained. The occupation rate of the modulation unit area 25a is also a constant value (zero). On the other hand, the occupation ratio of the first phase modulation unit region 25a in the modulation mask inclined portion 32 is a value in the range of 0 to about 0.5, and further toward the outside of the modulation region 22 (a). It is increasing monotonously.

  As described above, in the present embodiment, the modulation mask tilting portion 32 has the occupancy value of the first phase modulation unit region 25a equal to the occupancy value of the first phase modulation unit region 45a in the modulation mask peripheral portion 33. And the occupancy ratio of the first phase modulation unit region 25a in the modulation mask central portion 34 is defined as a region composed of the modulation unit region 24e having a value between them. In this case, as shown in FIG. 21B, the modulation mask inclined portion 32 is defined as a region composed of three (three) modulation unit regions 24e arranged in the radial direction. As described above, in the present embodiment, when the modulation unit region 24e is approximated by a square, the length of one side is 5 μm, and therefore, the width of the modulation mask inclined portion 32 in the modulation region 22 (a). z (a) is 15 μm.

  Here, in the graph of the occupancy ratio of the first phase modulation unit region, a portion where the occupancy value increases or decreases along the radial direction of the modulation region 22 (a) is defined as an occupancy gradient portion, and the occupancy gradient portion Let the width be z ′ (a). In this case, as shown in FIG. 21B, the width z ′ (a) of the occupying ratio inclined portion is larger than the width z (a) of the modulation mask inclined portion 32. Specifically, the width z ′ (a) of the occupying ratio inclined portion is larger than the width z (a) of the modulation mask inclined portion 32 by the width of one modulation unit region 24e. That is, the width z ′ (a) of the occupation rate inclined portion is 20 μm.

  As described above, the light phase-modulated and emitted by the modulation region 22 (a) generates a light intensity distribution based on the occupation ratio of the first phase modulation unit region on the imaging surface of the imaging optical system 17. For this reason, the unit gradation light 50 (a) modulated by the modulation region 22 (a) and irradiated onto the workpiece 18 has a light intensity based on the occupation ratio of the first phase modulation unit region in the modulation region 22 (a). Have a distribution. In this case, the width z ′ (a) of the occupying ratio inclined portion corresponds to the width w (a) of the inclined portion 52 in the unit gradation light 50 (a). Accordingly, the width w (a) of the inclined portion 52 of the unit gradation light 50 (a) that is modulated by the modulation region 22 (a) and applied to the workpiece 18 is 4 μm (20 μm × 1/5 (imaging optics). Magnification of system 17)).

  Similarly, the widths z ′ (e) and z ′ (i) of the occupying ratio inclined portions in the modulation region 22 (e) and the modulation region 22 (i) are 15 μm and 10 μm, respectively. Therefore, the widths w (e) and w (i) of the inclined portions 52 of the unit gradation light 50 (e) and (i) irradiated to the tapered holes 20 (e) and 20 (i) are 3 μm, respectively. 2 μm.

(Design procedure for non-modulation area)
Next, a design procedure for the non-modulation region 23 of the modulation mask 21 will be described. As shown in FIGS. 11A and 11B, the non-modulation region 23 includes a modulation mask main body 21a and a light shielding layer 21b provided on the modulation mask main body 21a. In this case, the light transmittance of the non-modulation region 23 is determined by the light transmittance of the light shielding layer 21b. That is, the light transmittance of the non-modulation region 23 is substantially equal to the light transmittance of the light shielding layer 21b.

As described above, the light transmittance of the light shielding layer 21b in the non-modulation region 23 is such that the intensity of light irradiated to the workpiece 18 through the non-modulation region 23 does not exceed the ablation threshold of the workpiece 18. It is selected appropriately. For example, when the non-modulation region 23 is not provided with the light shielding layer 21b, the light intensity on the image plane is 1000 mJ / cm ² and the ablation threshold of the workpiece 18 is 50 mJ / cm ^2. The light shielding layer 21b is selected so that the rate is less than 0.05. For this reason, it can prevent that the light which has the intensity | strength which can process the area | region in which the taper hole 20 is not formed among the to-be-processed objects 18 is radiate | emitted from the non-modulation area | region 23. It can prevent reliably that the area | region in which the taper hole 20 is not formed is processed.

(Modulation mask manufacturing method)
Thereafter, the modulation mask 21 having the modulation region 22 and the non-modulation region 23 is manufactured according to the designed pattern. In this case, the first phase modulation unit regions 25a and 45a are formed on the modulation mask main body 21a according to the designed pattern, for example, by photolithography. In addition, an appropriately selected light shielding layer 21b is provided on the modulation mask main body 21a. In this way, the modulation mask 21 is obtained.

(Taper hole forming method)
Next, a method for forming the tapered hole 20 in the workpiece 18 using the tapered hole forming apparatus 10 provided with the modulation mask 21 in the present embodiment will be described.

  First, the workpiece 18 is previously placed on the placing table 19. Next, laser light with a uniform in-plane intensity distribution is emitted from the mask illumination system 11. As the laser light, for example, an XeCl excimer laser having a wavelength of 308 nm and an oscillation time (per pulse) of 30 ns is used. Thereafter, the light emitted from the mask illumination system 11 is incident on the modulation mask 21 described above. The laser light incident on the modulation mask 21 is modulated or shielded according to the pattern of the modulation mask 21 determined by the above-described procedure.

  The laser light emitted from the modulation mask 21 is incident on the imaging optical system 17. As the imaging optical system 17, for example, an imaging optical system having a magnification (reduction ratio) of 1/5 and an imaging-side numerical aperture (NA) of 0.13 is used. As described above, the modulation unit conversion region obtained by converting the virtual modulation unit region 24e in each modulation region 22 of the modulation mask 21 into the imaging surface 17f of the imaging optical system 17 is the point image distribution range of the imaging optical system 17. The radius R is smaller in at least one direction. For this reason, the light intensity distribution of the laser light emitted from the imaging optical system 17 and imaged on the workpiece 18 after passing through each modulation area 22 is the first in each modulation unit area 24e of each modulation area 22. It has an intensity distribution corresponding to the occupation ratio of the phase modulation unit regions 25a and 45a.

  FIG. 22 shows taper holes 20 (a), 20 (e), and 20 (i) of laser light that is emitted from the imaging optical system 17 and forms an image on the workpiece 18 after passing through the modulation region 22. It is a figure which shows intensity distribution of unit gradation light 50 (a), 50 (e), and 50 (i) irradiated to. As described above, in the modulation regions 22 (a), 22 (e), and 22 (i), the widths z (a), z (e), and z (i) of the modulation mask inclined portions 32 are 15 μm and 10 μm, respectively. And 5 μm. Therefore, also in the corresponding unit gradation lights 50 (a), 50 (e) and 50 (i), the widths w (a), w (e) and w (i) of the inclined portion 52 are 4 μm, respectively. 3 μm and 2 μm. Thus, by increasing the width z of the modulation mask inclined portion 32 toward the end of the modulation mask 21, the width w of the inclined portion 52 of the unit gradation light 50 imaged on the workpiece 18 is increased. , And can be increased toward the end of the tapered holes 20 arranged in a row.

  FIG. 23A is a graph showing the width z of the modulation mask inclined portion 32 in each modulation region 22, and FIG. 23B is the result of modulation by each modulation mask inclined portion 32 and binding on the workpiece 18. It is a graph which shows the width w of the inclined part 52 of each unit gradation light 50 imaged. FIG. 23C is a graph showing the taper angle φ of the taper hole 20 formed by irradiating each unit gradation light 50. The width z of the modulation mask inclined portion 32 is appropriately adjusted according to the position of the tapered hole 20 (see FIG. 23A), thereby appropriately adjusting the width w of the inclined portion 52 of each unit gradation light 50. Thus (see FIG. 23B), as shown in FIG. 23C, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18. Yes.

  As described above, according to the present embodiment, the width w of the inclined portion 52 in one unit gradation light 50 among the unit gradation lights 50 is at least one unit gradation among the other unit gradation lights 50. This is different from the width of the inclined portion 52 in the light 50. For example, the width w of the inclined portion 52 in each unit gradation light 50 increases toward the end of the tapered holes 20 arranged in a line. Thereby, the taper angle φ of the tapered hole 20 formed by the irradiation of each unit gradation light 50 can be made substantially the same regardless of the position where each unit gradation light 50 is irradiated. As a result, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

  Further, according to the present embodiment, each modulation region 22 of the modulation mask 21 is located on the outer edge of the modulation mask central portion 34 and is irradiated to a region where the tapered portion 20 b of the tapered hole 20 is formed in the workpiece 18. And a modulation mask inclined portion 32 for modulating the light. Each modulation mask inclined section 32 is composed of a plurality of modulation unit regions 24e, where the radius R of the point image distribution range of the imaging optical system 17 is set to the light center wavelength λ, the emission side of the imaging optical system. When the numerical aperture NA is defined as R = 0.61λ / NA, the modulation unit conversion region obtained by converting the modulation unit region 24e into the imaging surface of the imaging optical system 17 is a point image of the imaging optical system 17. It is smaller in at least one direction than the radius of the distribution range. For this reason, the width z of the modulation mask inclined portion 32 in one modulation region 22 among the modulation regions 22 is arbitrarily different from the width of the modulation mask inclined portion 32 in at least one modulation region 22 among the other modulation regions 22. Can be made. For example, the width z of the modulation mask inclined part 32 can be set so as to increase toward the end of the modulation mask 21. As a result, the width w of the inclined portion 52 in each unit gradation light 50 that is modulated by each modulation region 22 and applied to the workpiece 18 can be increased toward the ends of the tapered holes 20 arranged in a row. . Therefore, the taper angle φ of the tapered hole 20 formed by irradiation of each unit gradation light 50 can be made substantially the same regardless of the position where each unit gradation light 50 is irradiated. As a result, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

  Further, according to the present embodiment, in each modulation region 22, the number of modulation unit regions 24e arranged in the width direction of the modulation mask inclined portion 32 increases as it goes to the end of the column. Thus, by increasing or decreasing the number of modulation unit regions 24e, the width z of each modulation mask inclined portion 32 can be increased or decreased. This makes it possible to easily adjust the width w of the inclined portion 52 in each unit gradation light 50 that is modulated by each modulation region 22 and applied to the workpiece 18 according to the position of the tapered hole 20. It has become.

(Modification)
In the present embodiment, the example in which the width z of the modulation mask inclined portion 32 is set so as to increase toward the end of the modulation mask 21 is shown. However, the present invention is not limited to this.
For example, consider a case where the distance between each tapered hole 20 is large. In this case, the scattered matter generated in one tapered hole forming region hardly reaches the other tapered hole forming region. On the other hand, the aberration of the unit gradation light 50 (a) irradiated to the tapered hole 20 (a) located at the end part is the unit gradation light 50 (irradiation to the tapered hole 20 (i) located at the center part. This is considered to be larger than the aberration i). Therefore, the width w (a) of the inclined portion 52 (a) of the unit gradation light 50 (a) at the end and the width w of the inclined portion 52 (i) of the unit gradation light 50 (i) at the center. When (i) is the same, the taper angle φ (a) of the end tapered hole 20 (a) is larger than the taper angle φ (i) of the central tapered hole 20 (i). Become.
In this case, as shown in FIG. 24A, the width z of the modulation mask inclined portion 32 is set so as to decrease toward the end of the modulation mask 21. Accordingly, as shown in FIG. 24B, the width w of the inclined portion 52 in each unit gradation light 50 that is modulated by each modulation region 22 and is irradiated on the workpiece 18 is aligned in a row. It can be made smaller as it goes to the edge of the. Accordingly, as shown in FIG. 24C, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

  Further, when the influence of the scattered object and the influence of the light aberration are mixed in the same size, as shown in FIGS. 25A and 25B, the width z of each modulation mask inclined portion 32 and each unit floor are obtained. The width w of the inclined portion 52 in the light control 50 can be flexibly set according to the position of the tapered hole 20. As a result, as shown in FIG. 25C, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

(Other variations)
In the modulation mask inclined part 32 according to the present embodiment, the area of the first phase modulation unit region 25a monotonously increases toward the outside of the modulation region 22, but is not limited thereto. The area of the first phase modulation unit region 25a monotonously decreases as the difference between the occupancy rate of the first phase modulation unit region 25a and the occupancy rate of the second phase modulation unit region 25b goes outward from the modulation region 22. It only has to be set to do. In other words, when the occupation ratio of the first phase modulation unit region 25a in the modulation mask inclined portion 32 is smaller than 0.5, the area of the first phase modulation unit region 25a monotonizes toward the outside of the modulation region 22. Set to increase. On the other hand, when the occupation ratio of the first phase modulation unit region 25a in the modulation mask inclined part 32 is larger than 0.5, the area of the first phase modulation unit region 25a monotonizes toward the outside of the modulation region 22. Set to decrease.

  Further, in the present embodiment, an example is shown in which the modulation mask central portion 34 is composed only of the second phase modulation unit region 25b that modulates light with the second phase modulation amount. However, the present invention is not limited to this, and the modulation mask central portion 34 may be composed of the first phase modulation unit region 25a and the second phase modulation unit region 25b. In this case, the light intensity P of the light (the central portion 51 of the unit gradation light 50) emitted from the modulation mask central portion 34 and applied to the workpiece 18 forms the through portion 20a of the tapered hole 20. The difference between the occupation ratio of the first phase modulation unit region 25a and the occupation ratio of the second phase modulation unit region 25b in the modulation mask central portion 34 is appropriately set so as to have a sufficient size.

(Significance of shape and pattern of first phase modulation unit region)
Next, the significance of setting the shape and pattern of the first phase modulation unit region 25a as shown in FIGS. 12 to 14 will be described as a supplement.

  In order to arrange the first phase modulation unit regions 25 a on the predetermined circumferential direction line 27 completely and periodically, the side edges of the first phase modulation unit regions 25 a are arranged on the modulation mask inclined portion 32 of the modulation region 22. It must extend along either the radial or circumferential direction. That is, it is necessary to change the direction in which the side edge extends in accordance with the location where the first phase modulation unit region 25a is disposed. Therefore, when the side edges of the respective first phase modulation unit regions 25a extend along the x direction and the y direction as described above, the first phase modulation unit regions 25a are arranged on a predetermined circumferential line. They cannot be arranged perfectly periodically, resulting in slight imperfections.

  However, as described above, the length obtained by converting the length of the side edge of the first phase modulation unit region 25a to the imaging surface 17f of the imaging optical system 17 is the radius of the point image distribution range of the imaging optical system 17. When it is sufficiently smaller than R, the light that is phase-modulated and emitted by the modulation mask tilting portion 32 of the modulation region 22 of the modulation mask 21 is incident on the imaging surface of the imaging optical system 17 on the first phase modulation unit region 25a. A light intensity distribution based on the occupancy ratio is generated. In this case, whether or not the light intensity distribution on the imaging surface of the imaging optical system 17 has a circular isointensity line is determined based on the first phase modulation unit on the predetermined circumferential direction line of the modulation mask inclined portion 32 of the modulation mask 21. This is determined by whether the distribution of the occupation ratio of the region 25a is periodic. Therefore, it is important to arrange each first phase modulation unit region 25a so that the distribution of the occupation ratio of the first phase modulation unit region 25a is periodic on the predetermined circumferential direction line 27 of the modulation mask inclined portion 32. It becomes. That is, the light intensity distribution on the imaging plane of the imaging optical system 17 is caused by slight imperfections in periodicity due to the side edges of the first phase modulation unit regions 25a extending in the x direction or the y direction. The effect on the can be ignored.

  On the other hand, in producing the modulation mask 21, considering that scanning exposure of the photosensitive material with a laser beam or an electron beam is performed based on an orthogonal coordinate system, the side edge of each first phase modulation unit region 25a is in the x direction. And preferably extending in the y direction. This is because the side edge of each first phase modulation unit region 25a is in one of two directions, the x direction and the y direction, as compared with the case where the side edge of each first phase modulation unit region 25a extends in various directions. This is because the amount of data used for scanning exposure is smaller and the exposure time is shorter when only the length is extended. Therefore, in the present embodiment, the first phase modulation unit region 25a whose side edge extends only in one of the two directions of the x direction and the y direction is employed in the modulation mask inclined portion 32. However, in view of the technical idea of the present invention, each first phase modulation unit region 25a may extend in a direction other than the x direction or the y direction, for example, the radial direction and the circumferential direction.

  It should be noted that the length obtained by converting the length of the first phase modulation unit region 25a to the imaging surface 17f of the imaging optical system 17 is not negligible compared to the radius R of the point image distribution range of the imaging optical system 17. If it is large, slight incompleteness of periodicity due to the side edge of each first phase modulation unit region 25a extending in the x direction or the y direction is the light intensity on the imaging surface of the imaging optical system 17. The influence on the distribution cannot be ignored. Specifically, it is conceivable that the isointensity line on the imaging surface of the imaging optical system 17 is not a perfect circle but a slightly wavy circle. In such a case, it is preferable to use the first phase modulation unit region 45a as shown in the modulation mask peripheral portion 33 of FIG.

According to the arrangement method of the first phase modulation unit region 25a described above, the modulation mask inclined portion 32 of the modulation region 22 has a predetermined area along the circumferential line 27, and each has one first phase modulation. It can be partitioned into a plurality of modulation unit regions 24e including the unit region 25a. On the other hand, when the first phase modulation unit region 25a is not arranged as described above, the area of the modulation unit region 24e on the same circumferential direction line 27 cannot be made constant. In this case, the relationship of [Equation 14] (or the relationship of [Equation 17] in the second embodiment described later) is not established. Therefore, in order to generate a desired light intensity distribution on the imaging surface of the imaging optical system 17 without arranging the first phase modulation unit region 25a as described above, the first phase modulation unit region 25a is used. It is necessary to calculate and obtain the area for each position individually, which is not preferable because the design of the modulation mask inclined portion 32 becomes complicated. Even when a uniform light intensity distribution is generated on the imaging surface of the imaging optical system 17, the area of the first phase modulation unit region 25a needs to be changed variously. It is not preferable to change the area of the first phase modulation unit region 25a in this way because it is difficult to manufacture the modulation mask 21.
On the other hand, according to the present embodiment, by arranging the first phase modulation unit region 25a as described above, a light intensity distribution having a circular isointensity line on the imaging surface of the imaging optical system 17 is obtained. The modulation mask inclined portion 32 of the modulation mask 21 that can be generated can be designed by simple calculation. In addition, the area of each first phase modulation unit region 25a on the same circumferential direction line 27 is constant, so that the modulation mask 21 can be easily manufactured.

  Further, as described above, the side edges constituting the first phase modulation unit region 25a are composed of a pair of x-direction side edges 28a extending in the x-direction and a pair of y-direction side edges 28b extending in the y-direction. For this reason, it is used when the first phase modulation unit region 25a is formed on the modulation mask body 21a by the photolithography method as compared with the case where the side edges constituting the first phase modulation unit region 25a extend in various directions. The structure of the exposure mask to be obtained is simple. Therefore, the manufacturing cost of the exposure mask is low, and this makes it possible to form the first phase modulation unit region 25a more easily and at low cost.

  Further, as described above, in the modulation mask inclined portion 32, the first phase modulation unit regions 25a are periodically arranged along a plurality of virtual circumferential lines 27 provided in an annular shape. In each circumferential direction line 27, the areas of two first phase modulation unit regions 25a adjacent on the same circumferential direction line 27 are substantially constant. As a result, as shown in FIG. 18, the inclined portion 52 of the unit gradation light 50 can be changed to light having a circular isointensity line.

Note that the first feature of the present embodiment is that the width z of the modulation mask inclined portion 32 of each modulation region 22 is adjusted according to the position of the tapered hole 20, whereby the inclined portion in each unit gradation light 50. 52 is to optimize the width w. Therefore, setting the shape and arrangement of the first phase modulation unit region 25a as described above is an additional matter, and is not limited to such a shape and arrangement. For example, as shown in FIGS. 26A and 26B, the first phase modulation unit regions 25a may be arranged in a lattice shape, and each first phase modulation unit region 25a may have a square shape.
Also in the modulation region 22 shown in FIGS. 26A and 26B, the occupation ratio of the first phase modulation unit region 25a in a part of the modulation unit regions 24e is set so as to monotonously increase or decrease toward the outside of the modulation region 22. Has been. Further, it is a value between the value of the occupation ratio of the first phase modulation unit region 25a in the peripheral edge portion 33 of the modulation mask and the value of the occupation ratio of the first phase modulation unit region 25a in the central portion 34 of the modulation mask. A region composed of the modulation unit region 24 e is a modulation mask inclined portion 32. Then, the width z of the modulation mask inclined portion 32 is adjusted according to the technical idea of the present invention.

  Further, in the present embodiment, an example in which the modulation region 22 has a circular outline is shown. However, the present invention is not limited to this. In the modulation region 22, it is sufficient that the contours of the modulation mask inclined portion 32 and the modulation mask central portion 34 are substantially circular. Therefore, as shown in FIG. 26A, the contour of the modulation region 22 (the modulation mask peripheral portion 33). ) May be non-circular.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. The second embodiment shown in FIGS. 27 to 29 is different in that each modulation unit region of the modulation region of the modulation mask is composed of a first amplitude modulation unit region and a second amplitude modulation region for amplitude-modulating light. Other configurations are substantially the same as those of the first embodiment shown in FIGS. In the second embodiment shown in FIGS. 27 to 29, the same parts as those in the first embodiment shown in FIGS.

(Modulation area of modulation mask)
As in the case of the first embodiment shown in FIGS. 1 to 26, the modulation region 22 of the modulation mask 21 is irradiated with light to the region where the penetrating portion 20 a of the tapered hole 20 is formed in the workpiece 18. A modulation mask central portion 34 that modulates light, and a modulation mask inclined portion that modulates light irradiated to a region where the tapered portion 20b of the tapered hole 20 is formed in the workpiece 18 at the outer edge of the modulation mask central portion 34. 32 and a modulation mask peripheral edge portion 33 located at the outer edge of the modulation mask inclined portion 32.

  Of these, the modulation mask peripheral portion 33 is composed only of a first amplitude modulation unit region (first modulation unit region) 26a for modulating light with a first amplitude modulation amount (first modulation amount). The modulation mask central portion 34 is composed only of a second amplitude modulation unit region (second modulation unit region) 26b that modulates light with a second amplitude modulation amount (second modulation amount). The structures of the first amplitude modulation unit region 26a and the second amplitude modulation unit region 26b will be described later.

(Modulation mask slope)
Next, the modulation mask inclined part 32 will be described. As shown in FIG. 27, the modulation mask inclined portion 32 of the modulation region 22 includes a first amplitude modulation unit region 26a, a second amplitude modulation unit region 26b formed so as to fill each first amplitude modulation unit region 26a, have.

  As shown in FIG. 28, each first amplitude modulation unit region 26a is arranged so that the center thereof is located on the same ring. Specifically, as shown in FIG. 28, each first amplitude modulation unit region 26 a has a center on a plurality of virtual circumferential direction lines 27 virtually provided in the modulation mask inclined portion 32. It is arranged to be located in.

  Next, the shape of the first amplitude modulation unit region 26a in the modulation mask inclined part 32 will be described. As shown in FIG. 28, each first amplitude modulation unit region 26 a includes two side edges 26 c and 26 c each having a substantially constant length extending in the radial direction of the modulation mask inclined portion 32. For this reason, when the modulation mask inclined portion 32 is partitioned into a plurality of unit modulation regions 24e, the area ratio of the first amplitude modulation unit region 26a in each unit modulation region 24e can be easily increased.

Note in the example shown in FIG. 28, the radial distance L ₁ between the circumferential line 27 adjacent has become substantially constant, and therefore, also substantially constant the length of the side edges 26c of the first amplitude modulation unit region 26a (= L ₁ ).

In addition, as shown in FIG. 28, the circumferential distance L ₂ between the centers of two first amplitude modulation unit region 26a adjacent on the same circumferential line 27, it is substantially constant. Further, not only between the first amplitude modulation unit regions 26a arranged on the same circumferential direction line 27 but also between the first amplitude modulation unit regions 26a arranged on all the same circumferential direction lines 27, the above-mentioned circumferential distance L ₂ between the centers are substantially constant. Further, the circumferential length L ₃ of the two first amplitude modulation unit region 26a adjacent on the same circumferential line 27 are substantially the same. As a result, the occupation ratio of the first amplitude modulation unit region 26a when viewed along the circumferential line 27 can be made substantially constant.

Next, a description will be given radial distance L ₁ and the circumferential distance L ₂ above. The radius R of the point image distribution range of the imaging optical system 17 is defined as R = 0.61λ / NA using the center wavelength λ of light from the laser light source 12 and the numerical aperture NA on the exit side of the imaging optical system 17. when the distance in terms of imaging surface 17f of the radial distance L ₁ and the circumferential distance L ₂ each imaging optical system 17, is smaller than the radius R of the point spread function range of the imaging optical system 17 ing. Here, “the distance obtained by converting the radial distance L ₁ and the circumferential distance L ₂ into the imaging surface 17 f of the imaging optical system 17” means the radial distance L ₁ and the circumferential distance L in the modulation mask 21. It is a value obtained by multiplying ₂ by the magnification of the imaging optical system 17.

Next, the occupation ratio of the first amplitude modulation unit region 26a will be described with reference to FIG. First, as shown by a dotted line in FIG. 28, the modulation mask inclined portion 32 is partitioned into a plurality of modulation unit regions 24e each having a predetermined area and each including one first amplitude modulation unit region 26a.
The dotted lines in FIG. 28 that define the modulation unit region 24e are, for example, a circumferential line extending along an intermediate point between two adjacent circumferential lines 27, and two adjacent lines on the circumferential line 27. And a radial line extending perpendicular to a line connecting the centers of the first amplitude modulation unit regions 26a. By drawing the dotted line shown in FIG. 28 in this way, the modulation mask inclined portion 32 is partitioned into a plurality of modulation unit regions 24e each having a predetermined area and each including one first amplitude modulation unit region 26a. be able to. In this case, the occupation ratio of the first amplitude modulation unit region 26a is defined as the area ratio of the first amplitude modulation unit region 26a in each modulation unit region 24e.

Here, when each modulation unit region 24e is approximated by a rectangle, the length of one side of the rectangle is substantially equal to L ₁ and L ₂ . Therefore, the modulation unit conversion region obtained by converting each modulation unit region 24e to the image formation surface 17f of the image formation optical system 17 is smaller than the radius R of the point image distribution range of the image formation optical system 17 in at least one direction. ing. For this reason, the light which is modulated by the modulation mask inclined portion 32 and is irradiated on the workpiece 18 has an intensity distribution based on the occupation ratio of the second amplitude modulation unit region 26b, as will be described later.

  Next, the structure of the first amplitude modulation unit region 26a and the second amplitude modulation unit region 26b of the modulation region 22 will be described with reference to FIG. As shown in FIG. 29, in the modulation region 22, a light shielding layer 29 is partially provided on the modulation mask main body 21a, and each of the light shielding layer 29 and the modulation mask main body 21a allows A first amplitude modulation unit region 26a is configured. On the other hand, the second amplitude modulation unit region 26b is a region of the modulation mask main body 21a where the light shielding layer 29 is not provided. In this case, the light transmittance in the first amplitude modulation unit region 26a is substantially 0, and the light transmittance in the second amplitude modulation unit region 26b is substantially 1.

  The light shielding layer 29 of the first amplitude modulation unit region 26a is made of a material that does not transmit light. For this reason, the light incident on the first amplitude modulation unit region 26 a of the modulation region 22 of the modulation mask 21 is shielded by the light shielding layer 29 without being taken out from the imaging optical system 17 side of the modulation mask 21. As the material of the light shielding layer 29, for example, various light shielding materials such as chromium, aluminum, silicon oxide, or a dielectric multilayer film can be used.

  Next, light based on the area ratio of the first amplitude modulation unit region 26a in each modulation unit region 24e is projected onto the imaging surface of the imaging optical system 17 from the light that is amplitude-modulated by the modulation region 22 of the modulation mask 21. The principle of generating the intensity distribution will be described.

ここで、Ｄ_ａ，ｉは、変調領域２２のうち第ｉ番目の変調単位領域２４ｅにおける開口率（変調単位領域２４ｅに対する第２振幅変調単位領域２６ｂの面積率）、Ｕ_ｉは結像面１７ｆのうちこの第ｉ番目の領域に対応する位置における複素振幅透過率である。 The modulation region 22 in the present embodiment is composed of a first amplitude modulation unit region 26a having a transmittance of 0 and a second amplitude modulation unit region 26b having a transmittance of 1. Therefore, the complex amplitude transmittance distribution T (x, y) in the modulation region 22 is T (x, y) = 0 when the point (x, y) is in the first amplitude modulation unit region 26a, and the point (x , y) is in the second amplitude modulation unit region 26b, T (x, y) = 1. Therefore, the following [Equation 15] is obtained by replacing the integration range of [Equation 7] with the inside of the modulation unit region 24e including (x, y).

Here, D _{a, i} is the aperture ratio in the i-th modulation unit region 24e of the modulation region 22 (the area ratio of the second amplitude modulation unit region 26b with respect to the modulation unit region 24e), and U _i is the imaging plane 17f. Is the complex amplitude transmittance at the position corresponding to the i-th region.

Since the intensity I of the laser light applied to the imaging surface 17f, that is, the workpiece 18, is given by the square of the absolute value of the complex amplitude transmittance U, the following [Equation 16] and [Equation 17] are derived. .

  Here, for I, the intensity distribution of the laser beam irradiated to the workpiece 18 based on [Equation 2] according to the size of the tapered hole 20 formed in the workpiece 18, the inclination angle of the tapered portion 20b, and the like. I can be set. Furthermore, the aperture ratio in each modulation unit region 24e of the modulation region 22 can be set according to [Equation 17] so that a desired laser light intensity distribution I can be obtained. Accordingly, by preparing the modulation mask 21 having the predetermined modulation region 22, it is possible to form the tapered hole 20 having a desired size, inclination angle, and the like in the workpiece 18.

  Next, the operation of the present embodiment having such a configuration will be described. Here, a method of forming 18 tapered holes 20 having the same taper angle φ on the workpiece 18 using the tapered hole forming apparatus 10 provided with the modulation mask 21 will be described.

(Modulation mask design procedure)
First, the design procedure of the modulation mask 21 will be described. FIG. 20 is a flowchart showing a procedure for designing the modulation region 22 of the modulation mask 21.

The design procedure of the modulation mask 21 shown in FIG. 30 is as follows. After the laser light intensity distribution I (x, y) is calculated (S208), each modulation in each modulation region 22 of the modulation mask 21 is calculated based on [Equation 17]. The only difference is that the aperture ratio D _a in the unit region 24e (the area ratio of the second amplitude modulation unit region 26b in each modulation unit region 24e) is calculated (S209), and the other procedures are as shown in FIG. The design procedure of the modulation mask 21 in the first embodiment is substantially the same.
Further, the design procedure of the arrangement pattern of the first amplitude modulation unit region 26a in each modulation region 22 is substantially the same as that of the first phase modulation unit region 25a in the first embodiment shown in FIG. The detailed explanation is omitted.

  Specific designed modulation regions 22 are shown in FIGS. 31 (a), 31 (b), and 31 (c). 31 (a), 31 (b), and 31 (c) show an end modulation area 22 (a), an intermediate modulation area 22 (e), and a central modulation area 22 (i), respectively. When the modulation unit area 24e of each modulation area 22 is approximated by a square, the square is approximately 5 μm on one side.

As shown in FIG. 31, the area of the first amplitude modulation unit region 26 a in the modulation mask inclined portion 32 is set to increase monotonously toward the outside of the modulation region 22. Specifically, in the end modulation region 22 (a), the circumferential length L _{3 of} the first amplitude modulation unit region 26 a is 0.65 μm in order from the inside toward the outside of the modulation region 22. , 1.45 μm and 2.5 μm. In the modulation region 22 of the intermediate section (e), the circumferential length _{L 3} of the first amplitude modulation unit region 26a is, 0.85 .mu.m in order toward the outside from the inside of the modulation region 22, and 2.15μm It is set to be. By setting the area of the first amplitude modulation unit region 26a in this way, it is possible to generate light (the inclined portion 52 of the unit gradation light 50) whose light intensity decreases monotonously toward the outside. In the central portion of the modulation region 22 (i), the circumferential length _{L 3} of the first amplitude modulation unit region 26a is in the 1.45 .mu.m.

  Further, as in the case of the first embodiment, the inclination of the unit gradation light 50 irradiated to the tapered holes 20 (a), 20 (e) and 20 (i) at the end portion, the intermediate portion, and the central portion. The widths w (a), w (e) and w (i) of the portion 52 are determined to be 4 μm, 3 μm and 2 μm, respectively. In this case, in the corresponding modulation regions 22 (a), 22 (e) and 22 (i), the widths z (a) and z of the modulation mask inclined portions 32 (a), 32 (e) and 32 (i) (E) and z (i) are set to 15 μm, 10 μm and 5 μm, respectively. Here, as shown in FIGS. 31 (a), (b), and (c), the widths z (a), z (e), and z in the modulation mask inclined portions 32 (a), 32 (e), and 32 (i), respectively. (I) is adjusted by increasing or decreasing the number of modulation unit regions 24e arranged in the width direction of the respective modulation mask inclined portions 32 (a), 32 (e) and 32 (i).

  As described above, also in the present embodiment, the width z of the modulation mask inclined portion 32 is appropriately adjusted according to the position of the tapered hole 20. Accordingly, the width w of the inclined portion 52 in each unit gradation light 50 that is modulated by each modulation region 22 and irradiated onto the workpiece 18 can be optimized according to the position of the tapered hole 20. Therefore, the taper angle φ of the tapered hole 20 formed by irradiation of each unit gradation light 50 can be made substantially the same regardless of the position where each unit gradation light 50 is irradiated. As a result, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

  In the present embodiment, the example in which the first amplitude modulation unit region 26 a of the modulation mask inclined part 32 includes the two side edges 26 c and 26 c having a substantially constant length extending in the radial direction of the modulation mask inclined part 32 has been described. However, the present invention is not limited to this, and the first amplitude modulation unit region 26a of the modulation mask inclined portion 32 is arranged in the x and y directions as in the case of the first phase modulation unit region 25a in the first embodiment. You may have the extended rectangular shape.

Third Embodiment Next, with reference to FIGS. 32 and 33, a third embodiment of the present invention will be described. The third embodiment shown in FIGS. 32 and 33 differs only in that the width z of each modulation mask inclined portion 32 is adjusted by increasing or decreasing the size of the modulation unit region 24e. Is substantially the same as the first embodiment shown in FIGS. In the third embodiment shown in FIGS. 32 and 33, the same parts as those in the first embodiment shown in FIGS.

  FIGS. 32A, 32B, and 32C show the modulation region 22 (a) at the end, the modulation region 22 (e) at the middle portion, and the modulation region 22 (at the central portion) in the modulation mask 21 according to the present embodiment. It is a figure which shows i) respectively.

  In the present embodiment, it is required to adjust the width w of the inclined portion 52 of the unit gradation light 50 irradiated to the workpiece 18 more precisely than in the case of the first embodiment described above. It has been. For example, the width w (a), w (e) of the inclined portion 52 of the unit gradation light 50 irradiated to the tapered holes 20 (a), 20 (e), and 20 (i) at the end, middle, and center. ) And w (i) are required to be adjusted to 3.4 μm, 2.8 μm, and 2.2 μm, respectively. For this reason, in the present embodiment, the number of the modulation unit regions 24e arranged in the width direction of the modulation mask inclined portion 32 is not increased or decreased, but in the width direction of the modulation unit regions 24e aligned in the width direction of the modulation mask inclined portion 32. By adjusting the dimensions, the width w of the inclined portion 52 of the unit gradation light 50 is optimized.

In the modulation mask inclined portion 32 (a) of the end portion shown in FIG. 32 (a), for example, the radial distance L ₁ between the circumferential line 27 is set to 5 [mu] m. Accordingly, the dimension in the width direction of the modulation unit regions 24e arranged in the width direction of the modulation mask inclined portion 32 is also about 5 μm. As a result, the width z (a) of the modulation mask inclined portion 32 (a) is about 10 μm.
In the modulating mask inclined portion 32 of the intermediate part (e) shown in FIG. 32 (b), for example, the radial distance L ₁ between the circumferential line 27 is set to 4 [mu] m. Accordingly, the dimension in the width direction of the modulation unit region 24e aligned in the width direction of the modulation mask inclined portion 32 is also about 4 μm. As a result, the width z (e) of the modulation mask inclined portion 32 (e) is about 8 μm.
In the modulating mask inclined section 32 (i) of the central portion shown in FIG. 32 (c), for example, the radial distance L ₁ between the circumferential line 27 is set to 3 [mu] m. Therefore, the dimension in the width direction of the modulation unit region 24e aligned in the width direction of the modulation mask inclined portion 32 is also about 3 μm. As a result, the width z (i) of the modulation mask inclined portion 32 (i) is about 6 μm.

  FIG. 33 shows taper holes 20 (a), 20 (e), and 20 (i) of the laser light emitted from the imaging optical system 17 and imaged on the workpiece 18 after passing through the modulation region 22. It is a figure which shows intensity distribution of unit gradation light 50 (a), 50 (e), and 50 (i) irradiated to. As described above, in the modulation regions 22 (a), 22 (e) and 22 (i), the widths z (a), z (e) and z (i) of the respective modulation mask inclined portions 32 are 10 μm and 8 μm, respectively. And 6 μm. Therefore, in the corresponding unit gradation lights 50 (a), 50 (e) and 50 (i), the widths w (a), w (e) and w (i) of the inclined portion 52 are 3. They are 4 μm, 2.8 μm and 2.2 μm. Thus, by increasing the width z of the modulation mask inclined portion 32 toward the end of the modulation mask 21, the width w of the inclined portion 52 of the unit gradation light 50 imaged on the workpiece 18 is increased. , And can be increased toward the end of the tapered holes 20 arranged in a row.

Further, according to the present embodiment, in each modulation region 22, the dimension in the width direction of the modulation unit region 24e arranged in the width direction of the modulation mask inclined portion 32 increases toward the end of the column. In this way, by increasing or decreasing the dimension of the modulation unit region 24e in the width direction, the width z of each modulation mask inclined portion 32 can be increased or decreased more precisely. Thus, the width w of the inclined portion 52 in each unit gradation light 50 that is modulated by each modulation region 22 and irradiated onto the workpiece 18 can be adjusted more precisely according to the position of the tapered hole 20. It is possible.
Although the example in which the width z of the modulation mask inclined portion 32 is increased toward the end of the modulation mask 21 is shown, the present invention is not limited to this, and the modification example of the first embodiment shown in FIG. Similarly to the case, the width z of the modulation mask inclined portion 32 may become smaller toward the end of the modulation mask 21. In this case, in each modulation region 22, the dimension in the width direction of the modulation unit region 24e arranged in the width direction of the modulation mask inclined portion 32 becomes smaller toward the end of the column.

Fourth Embodiment Next, with reference to FIGS. 34 to 42, a fourth embodiment of the present invention will be described. In the fourth embodiment shown in FIG. 34 to FIG. 42, a plurality of tapers simultaneously formed on the workpiece by adjusting the light intensity of the central portion of the unit gradation light according to the position of the taper hole. The taper angle of the hole is optimized. In the fourth embodiment shown in FIGS. 34 to 42, the same parts as those in the first embodiment shown in FIGS.

(Features of this embodiment)
As described in the first embodiment, the taper angle φ of the tapered hole 20 depends on the light intensity P of the central portion 51 of the unit gradation light 50 or the width w of the inclined portion 52 of the unit gradation light 50. Change. In the first embodiment, the taper angle φ of the plurality of tapered holes 20 to be formed is increased by appropriately adjusting the width w of the inclined portion 52 of the unit gradation light 50 according to the position of the tapered hole 20. We showed how to make all of them almost the same. In the present embodiment, the magnitude of the taper angle φ of the plurality of taper holes 20 to be formed by appropriately adjusting the light intensity P of the central portion 51 of the unit gradation light 50 according to the position of the taper hole 20. A method of aligning all of them substantially the same will be described.

(Prerequisites in this embodiment)
When only one tapered hole 20 is formed in the workpiece 18, as shown by a solid line in FIG. 34, the light intensity P of the central portion 51 of the unit gradation light 50 irradiated to the workpiece 18, There is a relationship between the taper angle φ of the tapered hole 20 formed in the workpiece 18 that the taper angle φ increases as the light intensity P decreases.

(Taper angle when multiple tapered holes are formed simultaneously)
By the way, when the plurality of tapered holes 20 are simultaneously formed in the workpiece 18, as described in the first embodiment, the unit gradation lights 50 emitted from the tapered hole forming apparatus 10 are the same as each other. Even if it is light, it is possible that the intensity | strength of the unit gradation light 50 at the time of irradiating the workpiece 18 differs according to the position of a taper hole formation area.

Consider the case where the distance between each tapered hole 20 is small. In this case, as described in the first embodiment, the central tapered hole 20 (i) has a peripheral portion compared to the intermediate tapered hole 20 (e) or the end tapered hole 20 (a). Are greatly affected by the scattered matter from the taper hole 20. Further, the taper hole 20 (e) at the intermediate part is more influenced by the scattered matter from the peripheral taper hole 20 than the taper hole 20 (a) at the end part.
In this case, if the relationship between the taper angle φ (a) in the tapered hole 20 (a) at the end and the light intensity P of the central portion 51 is represented by the solid line shown in FIG. Regarding the tapered hole 20 (e), it can be said that the relationship between the taper angle φ (e) and the light intensity P of the central portion 51 shifts to the relationship indicated by the alternate long and short dash line in FIG. Regarding the central tapered hole 20 (i), it can be said that the relationship between the taper angle φ (i) and the light intensity P of the central portion 51 shifts to the relationship indicated by the two-dot chain line in FIG.

  Here, the light intensity of the central portion 51 in each unit gradation light 50 is decreased as it goes toward the end of the taper holes 20 arranged in a row (in other words, it increases as it goes to the center of the taper holes 20 arranged in a row). It is considered that the taper angle φ of the formed tapered hole 20 can be made substantially the same. That is, in the present embodiment, as shown in FIGS. 35 (a), (b), and (c), the light intensity P of the central portion 51 of the unit gradation light 50 irradiated to the tapered hole 20 (a) at the end portion. (A) is set to be smaller than the light intensity P (e) of the central portion 51 of the unit gradation light 50 irradiated to the taper hole 20 (e) in the intermediate portion. Further, the light intensity P (e) of the central portion 51 of the unit gradation light 50 irradiated to the taper hole 20 (e) in the middle portion is the unit gradation light irradiated to the taper hole 20 (i) in the center portion. It is set to be smaller than the light intensity P (i) of the central portion 51 of 50.

  FIG. 36A is a graph showing the light intensity P of the central portion 51 in each unit gradation light 50 in the example shown in FIGS. 35A, 35B, and 35C. FIG. It is a graph which shows taper angle (phi) of the taper hole 20 formed in the example shown to Fig.35 (a) (b) (c). As described above, by appropriately adjusting the light intensity P of the central portion 51 in each unit gradation light 50 according to the position of the tapered hole 20, the taper angles φ of the plurality of formed tapered holes 20 are made substantially the same. can do. In this case, the adjustment amount of the light intensity P of the central portion 51 is appropriately set according to the relationship shown in FIG. For example, as shown in FIG. 34, in the taper hole 20 (i) at the center, when the shift amount of the taper angle φ due to the amount of scattering is Δφ (i), the taper hole 20 (a) at the end. The light intensity P of the central portion 51 is set to be larger by ΔP (i) than

  FIG. 36A shows an example in which the light intensity P of the central portion 51 in each unit gradation light 50 is continuously adjusted according to the position of the tapered hole 20. However, it is not always necessary to continuously adjust the light intensity P of the central portion 51, and the light intensity P of the central portion 51 may be adjusted discretely as shown in FIG. Even in the case of such discrete adjustment, compared to the case where the light intensity P of the central portion 51 is not adjusted, the taper angle φ of the plurality of tapered holes 20 to be formed can be made uniform, It is advantageous.

  Next, the modulation region 22 of the modulation mask 21 for generating the unit gradation light 50 in which the light intensity P of the central portion 51 can be adjusted according to the position of the tapered hole 20 will be described with reference to FIGS. explain. FIG. 38 is a plan view showing the modulation region 22, and FIG. 39 is an enlarged view showing a portion surrounded by the frame XXXIX in the modulation region 22 shown in FIG.

(Modulation area)
As shown in FIG. 38, the modulation region 22 includes a modulation mask central portion 34 that modulates light applied to a region where the through portion 20 a of the tapered hole 20 is formed in the workpiece 18, and a modulation mask central portion 34. And a modulation mask peripheral edge portion 33 located at the outer edge.

(Center of modulation mask)
Among them, the modulation mask central portion 34 includes a number of first phase modulation unit regions (first modulation unit regions) 25a for modulating light with a first phase modulation amount (first modulation amount), and each first phase modulation. And a second phase modulation unit region (second modulation unit region) 25b that is formed so as to fill the unit region 25a and modulates light with a second phase modulation amount (second modulation amount). As shown in FIGS. 38 and 39, the shape and arrangement pattern of the first phase modulation unit region 25a are the same as the shape and arrangement pattern of the first phase modulation unit region 25a of the modulation mask inclined part 32 in the first embodiment. The detailed description is omitted.

  In the modulation mask central portion 34, as will be described later, in order to appropriately set the light intensity P of the central portion 51 of the unit gradation light 50 generated by being modulated by the modulation mask central portion 34, the first phase modulation unit region The occupation ratio of 25a is adjusted.

(Modulation mask edge)
As shown in FIG. 38, the modulation mask peripheral portion 33 is formed between a large number of first phase modulation unit regions 45a that modulate light with a first phase modulation amount and each first phase modulation unit region 45a. And a plurality of second phase modulation unit regions 45b for modulating the second phase modulation amount with the second phase modulation amount. As shown in FIGS. 38 and 39, the shape and arrangement pattern of the phase modulation unit regions 45a and 45b are the same as the shape and arrangement pattern of the phase modulation unit regions 45a and 45b of the modulation mask peripheral portion 33 in the first embodiment. The detailed description is omitted.

  Next, the operation of the present embodiment having such a configuration will be described. Here, a method of forming 18 tapered holes 20 having the same taper angle φ on the workpiece 18 using the tapered hole forming apparatus 10 provided with the modulation mask 21 will be described.

(Modulation mask design procedure)
First, the design procedure of the modulation mask 21 will be described. FIG. 40 is a flowchart showing a procedure for designing the modulation region 22 of the modulation mask 21.

(Modulation area design procedure)
(A) First, information (position (x, y), radius, depth, taper angle φ, etc.) regarding each tapered hole 20 formed in the workpiece 18 is input (S401). For example, 8 degrees is input as the taper angle φ. In addition, 30 μm and 50 μm are input as the radius and depth of the tapered hole 20.
(B) Next, the laser beam irradiation frequency m is input (S402). For example, 150 times is input as the number of times of irradiation m.
(C) Thereafter, based on the depth of the tapered hole 20 and the number of times of laser light irradiation, the initial value of the light intensity P of the central portion 51 of the unit gradation light 50 irradiated to the workpiece 18 (correction to be described later) A base value is calculated (S403). For example, 1000 mJ / cm ² is calculated as the initial value of the light intensity P of the central portion 51.
(D) Next, based on the relationship of FIG. 34, the value of the light intensity P of the central portion 51 of the unit gradation light 50 is corrected according to the position where the tapered hole 20 is to be formed (S404). For example, in the case of ablation, when it is anticipated that a large amount of scattered matter will pass between the tapered holes 20, the light intensity P of the central portion 51 of the unit gradation light 50 irradiated to the tapered hole 20 (a) at the end portion. The value of the light intensity P is corrected so that (a) is smaller than the light intensity P (i) of the central portion 51 of the unit gradation light 50 irradiated to the central tapered hole 20 (i). The A specific correction amount of the light intensity P is determined based on past experimental results. For example, the light intensities P (a) and P (P (a) of the central portion 51 of the unit gradation light 50 irradiated to the tapered holes 20 (a), 20 (e) and 20 (i) at the end, middle and center. e) and P (i) are determined to increase from 0.68 to 0.85 (relative value) from the end toward the center.
(E) Next, based on the calculated light intensity P and the position (x, y) and radius of the tapered hole 20, a desired ablation rate d (x, y) in the workpiece 18 is calculated (S405). ).
(F) Thereafter, based on d (x, y), the light intensity distribution I (x, y) of the light irradiated on the workpiece 18 is calculated (S406).
(G) Next, based on the intensity distribution I (x, y) of the laser beam and [Equation 14], the occupancy rates of the first phase modulation unit regions 25a and 45a in each modulation region 22 of the modulation mask 21 (each modulation) The area ratio D _p of the first phase modulation unit regions 25a and 45a in the unit region 24e is calculated (S407). Area ratio D _p is calculated for each was partitioned modulation unit area 24e as a unit area.
In (h) Finally, based on the calculated area ratio _{D p,} the first phase modulation unit areas 25a in each of the modulation area 22 in the modulation mask 21, the arrangement pattern of 45a is determined (S408).

  Next, the arrangement pattern of the first phase modulation unit regions 25a and 45a in each modulation region 22 is designed. The specific design method is substantially the same as that of the first embodiment shown in FIG.

  Specific modulation regions 22 designed as described above are shown in FIGS. 41 (a), (b), and (c). 41A, 41B, and 41C show the end modulation region 22 (a), the intermediate modulation region 22 (e), and the central modulation region 22 (i), respectively.

As described above, the light intensity P (a) of the central portion 51 of the unit gradation light 50 irradiated to the tapered holes 20 (a), 20 (e) and 20 (i) at the end portion, the intermediate portion, and the central portion. , P (e) and P (i) are determined to increase from 0.68 to 0.85 from the end toward the center. In this case, in the corresponding modulation regions 22 (a), 22 (e) and 22 (i), the first phase modulation unit regions 25a in the modulation mask central portions 34 (a), 34 (e) and 34 (i). dimension _{L 7} of one side is set so as to decrease the 1.5 [mu] m → 1.0 .mu.m toward the central portion from the end portion of the modulation mask 21. That is, the occupation ratio of the first phase modulation unit region 25a in each modulation unit region 24e of the modulation mask central portion 34 is set so as to decrease from the end of the modulation mask 21 toward the central portion. Further, the occupation ratio of the first phase modulation unit region 25a in each modulation unit region 24e of the modulation mask central portion 34 is smaller than 0.5. Accordingly, the difference between the occupation ratio of the first phase modulation unit region 25a and the occupation ratio of the second phase modulation unit region 25b in the modulation mask central portion 34 is set so as to increase from the end portion of the modulation mask 21 toward the central portion. Will be.

(Modulation mask manufacturing method)
Thereafter, the modulation mask 21 having the modulation region 22 and the non-modulation region 23 is manufactured according to the designed pattern. In this case, the first phase modulation unit regions 25a and 45a are formed on the modulation mask main body 21a according to the designed pattern, for example, by photolithography. In addition, an appropriately selected light shielding layer 21b is provided on the modulation mask main body 21a. In this way, the modulation mask 21 is obtained.

(Taper hole forming method)
Next, a method for forming the tapered hole 20 in the workpiece 18 using the tapered hole forming apparatus 10 provided with the modulation mask 21 in the present embodiment will be described.

  First, the workpiece 18 is previously placed on the placing table 19. Next, laser light with a uniform in-plane intensity distribution is emitted from the mask illumination system 11. As the laser light, for example, an XeCl excimer laser having a wavelength of 308 nm and an oscillation time (per pulse) of 30 ns is used. Thereafter, the light emitted from the mask illumination system 11 is incident on the modulation mask 21 described above. The laser light incident on the modulation mask 21 is modulated or shielded according to the pattern of the modulation mask 21 determined by the above-described procedure.

  The laser light emitted from the modulation mask 21 is incident on the imaging optical system 17. As the imaging optical system 17, for example, an imaging optical system having a magnification (reduction ratio) of 1/5 and an imaging-side numerical aperture (NA) of 0.13 is used. As described above, the modulation unit conversion region obtained by converting the virtual modulation unit region 24e in each modulation region 22 of the modulation mask 21 into the imaging surface 17f of the imaging optical system 17 is the point image distribution range of the imaging optical system 17. The radius R is smaller in at least one direction. For this reason, the light intensity distribution of the laser light emitted from the imaging optical system 17 and imaged on the workpiece 18 after passing through each modulation area 22 is the first in each modulation unit area 24e of each modulation area 22. It has an intensity distribution corresponding to the area ratio of the phase modulation unit regions 25a and 45a.

FIG. 42 shows tapered holes 20 (a), 20 (e), and 20 (i) of the laser light that is emitted from the imaging optical system 17 and forms an image on the workpiece 18 after passing through the modulation region 22. It is a figure which shows intensity distribution of unit gradation light 50 (a), 50 (e), and 50 (i) irradiated to. As described above, in the modulation regions 22 (a), 22 (e), and 22 (i), the dimension L _{7 on} one side of the first phase modulation unit region 25 a in each modulation mask central portion 34 is the end of the modulation mask 21. It is set to decrease as it goes from the center to the center. That is, the difference between the occupation ratio of the first phase modulation unit region 25a and the occupation ratio of the second phase modulation unit region 25b in the modulation mask central portion 34 is set so as to increase from the end portion of the modulation mask 21 toward the central portion. Has been. For this reason, also in the corresponding unit gradation light 50 (a), 50 (e) and 50 (i), the light intensities P (a), P (e) and P (i) of the central portion 51 are the end points. Increasing from the center to the center. Thus, the dimension L ₇ of one side of the first phase modulation unit region 25a in the modulator mask central portion 34, by decreasing toward the center portion of the modulation mask 21, unit is imaged onto the workpiece 18 The light intensity P of the central portion 51 of the gradation light 50 can be increased toward the central portion of the tapered holes 20 arranged in a row.

  As described above, according to the present embodiment, the light intensity P of the central portion 51 in one unit gradation light 50 among the unit gradation lights 50 is at least one unit floor among the other unit gradation lights 50. This is different from the light intensity P of the central portion 51 in the light control 50. For example, the light intensity P of the central portion 51 in each unit gradation light 50 becomes smaller toward the ends of the tapered holes 20 arranged in a row. Thereby, the taper angle φ of the tapered hole 20 formed by the irradiation of each unit gradation light 50 can be made substantially the same regardless of the position where each unit gradation light 50 is irradiated. As a result, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

  Further, according to the present embodiment, each modulation region 22 of the modulation mask 21 includes the modulation mask central portion 34 that modulates the light irradiated to the region where the through portion 20 a of the tapered hole 20 is formed in the workpiece 18. Contains. Each modulation mask central portion 34 is composed of a plurality of modulation unit regions 24e. Here, the radius R of the point image distribution range of the imaging optical system 17 is set to the light center wavelength λ, the emission side of the imaging optical system. When the numerical aperture NA is defined as R = 0.61λ / NA, the modulation unit conversion region obtained by converting the modulation unit region 24e into the imaging surface of the imaging optical system 17 is a point image of the imaging optical system 17. It is smaller in at least one direction than the radius of the distribution range. Each modulation unit region 24e includes a first phase modulation unit region 25a that modulates light with a first phase modulation amount, and a second phase modulation unit region 25b that modulates light with a second phase modulation amount. It has become. The occupation ratio of the first phase modulation unit region 25a in the modulation unit region 24e of each modulation mask central portion 34 is set to a predetermined value. Therefore, each unit gradation light 50 is irradiated with the light intensity P of the central portion 51 of each unit gradation light 50 irradiated to the workpiece 18 after being modulated by each modulation region 22 of the modulation mask 21. It can be changed arbitrarily according to the position. Thereby, the taper angle φ of the tapered hole 20 formed by the irradiation of each unit gradation light 50 can be made substantially the same regardless of the position where each unit gradation light 50 is irradiated. As a result, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

(Modification)
In the present embodiment, the difference between the occupation ratio of the first phase modulation unit region 25 a and the occupation ratio of the second phase modulation unit region 25 b in the modulation mask central portion 34 increases toward the central portion of the modulation mask 21. An example of setting is shown. However, the present invention is not limited to this.
For example, consider a case where the distance between each tapered hole 20 is large. In this case, scattered matter generated in one tapered hole 20 hardly reaches the other tapered hole 20. On the other hand, the aberration of the unit gradation light 50 (a) irradiated to the tapered hole 20 (a) located at the end part is the unit gradation light 50 (irradiation to the tapered hole 20 (i) located at the center part. This is considered to be larger than the aberration i). Therefore, the light intensity P (a) of the central portion 51 (a) of the unit gradation light 50 (a) at the end and the light of the central portion 51 (i) of the unit gradation light 50 (i) at the central portion. When the strength P (i) is the same, the taper angle φ (a) of the taper hole 20 (a) at the end is larger than the taper angle φ (i) of the taper hole 20 (i) at the center. Become bigger.
In this case, the occupancy of the first phase modulation unit region 25a and the second phase modulation in the modulation mask center 34 are based on the same technical idea as in the modification of the first embodiment shown in FIG. The difference from the occupancy ratio of the unit region 25 b is set so as to increase toward the end of the modulation mask 21. As a result, the light intensity P of the central portion 51 in each unit gradation light 50 that is modulated by each modulation region 22 and applied to the workpiece 18 can be increased toward the ends of the tapered holes 20 arranged in a row. it can. As a result, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

  Further, when the influence of the scattered object and the influence of the light aberration are mixed in the same magnitude, the occupation ratio of the first phase modulation unit area 25a and the second phase modulation unit area 25b in each modulation mask central portion 34 are mixed. The difference from the occupation ratio can be flexibly set according to the position of the tapered hole 20. As a result, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIGS. The fifth embodiment shown in FIGS. 43 to 45 is different in that each modulation unit area of the modulation area of the modulation mask is composed of a first amplitude modulation unit area for modulating the amplitude of light and a second amplitude modulation area. Other configurations are substantially the same as those of the fourth embodiment shown in FIGS. In the fifth embodiment shown in FIG. 43 to FIG. 45, the same parts as those in the fourth embodiment shown in FIG. 34 to FIG.

(Modulation area of modulation mask)
As in the case of the fourth embodiment shown in FIGS. 34 to 42, the modulation region 22 of the modulation mask 21 is irradiated with light to the region where the penetrating portion 20 a of the tapered hole 20 is formed in the workpiece 18. And a modulation mask peripheral portion 33 located on the outer edge of the modulation mask central portion 34.

(Center of modulation mask)
Of these, the modulation mask central portion 34 includes a number of first amplitude modulation unit regions (first modulation unit regions) 26a that modulate light with a first amplitude modulation amount (first modulation amount), and each first amplitude modulation. And a second amplitude modulation unit region (second modulation unit region) 26b that is formed so as to fill the unit region 26a and modulates light with a second amplitude modulation amount (second modulation amount). As shown in FIGS. 43 and 44, the shape and arrangement pattern of the first amplitude modulation unit region 26a are the same as the shape and arrangement pattern of the first phase modulation unit region 25a of the modulation mask central portion 34 in the fourth embodiment. The detailed description is omitted.

  In the modulation mask central portion 34, as in the case of the fourth embodiment, the light intensity P of the central portion 51 of the unit gradation light 50 generated by being modulated by the modulation mask central portion 34 is appropriately set. The occupation ratio of the first amplitude modulation unit region 26a of each modulation unit region 24e is adjusted.

(Modulation mask edge)
As shown in FIG. 43, the modulation mask peripheral portion 33 is composed of only a first amplitude modulation unit region (first modulation unit region) 26a for modulating light with a first amplitude modulation amount (first modulation amount). Yes. The modulation mask peripheral portion 33 is substantially the same as the modulation mask peripheral portion 33 in the second embodiment shown in FIGS. 27 to 29, and a detailed description thereof is omitted.

  Further, the structures of the first amplitude modulation unit region 26a and the second amplitude modulation unit region 26b in the modulation mask central portion 34 and the modulation mask peripheral portion 33 are the first amplitude in the second embodiment shown in FIGS. The structures of the modulation unit region 26a and the second amplitude modulation unit region 26b are substantially the same, and detailed description thereof is omitted.

  Next, the operation of the present embodiment having such a configuration will be described. Here, a method of forming 18 tapered holes 20 having the same taper angle φ on the workpiece 18 using the tapered hole forming apparatus 10 provided with the modulation mask 21 will be described.

(Modulation mask design)
First, the modulation mask 21 is designed. In the design procedure of the modulation mask 21 in the present embodiment, after the laser light intensity distribution I (x, y) is calculated, the modulation unit of each modulation mask central portion 34 of the modulation mask 21 is calculated based on [Equation 17]. The only difference is that the aperture ratio D _a (area ratio of the second amplitude modulation unit region 26b in each modulation unit region 24e) in the region 24e is calculated, and the other procedures are the same as those in the fourth embodiment shown in FIG. This is substantially the same as the design procedure of the modulation mask 21 in the embodiment. It should be noted that the light intensity P (a) and P (P ( As in the case of the fourth embodiment, e) and P (i) are set to increase from 0.68 to 0.85 from the end toward the center.
Further, the design procedure of the arrangement pattern of the first amplitude modulation unit region 26a in each modulation mask central portion 34 is also substantially the same as that of the first phase modulation unit region 25a in the fourth embodiment shown in FIG. Detailed description will be omitted.

  Specific designed modulation regions 22 are shown in FIGS. 45 (a), (b) and (c). 45 (a), 45 (b), and 45 (c) respectively show an end modulation area 22 (a), an intermediate modulation area 22 (e), and a central modulation area 22 (i). When the modulation unit area 24e of each modulation area 22 is approximated by a square, the square is approximately 5 μm on one side.

As described above, the light intensity P (a) of the central portion 51 of the unit gradation light 50 irradiated to the tapered holes 20 (a), 20 (e) and 20 (i) at the end portion, the intermediate portion, and the central portion. , P (e) and P (i) are set to increase from 0.68 to 0.85 from the end toward the center. In this case, in the corresponding modulation regions 22 (a), 22 (e) and 22 (i), the first amplitude modulation unit regions 26a in the modulation mask central portions 34 (a), 34 (e) and 34 (i). dimension _{L 7} of one side is set so as to decrease the 2.1 .mu.m → 1.4 [mu] m toward the central portion from the end portion of the modulation mask 21. In other words, the area ratio of the first amplitude modulation unit region 26 a in each modulation unit region 24 e of the modulation mask center 34 is set to increase from the end of the modulation mask 21 toward the center. Therefore, the aperture ratio of each modulation unit region 24e in the modulation mask central portion 34 (the area ratio of the second amplitude modulation unit region 26b in each modulation unit region 24e) increases from the end of the modulation mask 21 toward the center. Will be set as follows.

(Modulation mask manufacturing method)
Thereafter, the modulation mask 21 having the modulation region 22 and the non-modulation region 23 is manufactured according to the designed pattern. In this case, the light shielding layer 21a and the light shielding layer 29 are provided in a predetermined pattern on the modulation mask body 21a so that the designed pattern is formed. In this way, the modulation mask 21 is obtained.

(Taper hole forming method)
Thereafter, in the same manner as in the fourth embodiment, 18 tapered holes 20 are formed in the workpiece 18 by using the tapered hole forming apparatus 10 including the modulation mask 21 according to the present embodiment. .

At this time, as described above, modulation region 22 (a), in 22 (e) and 22 (i), the dimension _{L 7} of one side of the first amplitude modulation unit region 26a in each modulation mask central portion 34, the modulation mask It is set to decrease from the end of 21 toward the center. That is, the aperture ratio of each modulation unit region 24e in the modulation mask central portion 34 is set so as to increase from the end of the modulation mask 21 toward the central portion. For this reason, also in the corresponding unit gradation light 50 (a), 50 (e) and 50 (i), the light intensities P (a), P (e) and P (i) of the central portion 51 are the end points. Increasing from the center to the center. Thus, the dimension L ₇ of one side of the first amplitude modulation unit region 26a in the modulator mask central portion 34, by decreasing toward the center portion of the modulation mask 21, unit is imaged onto the workpiece 18 The light intensity P of the central portion 51 of the gradation light 50 can be increased toward the central portion of the tapered holes 20 arranged in a row.

  As described above, according to the present embodiment, the light intensity P of the central portion 51 in one unit gradation light 50 among the unit gradation lights 50 is at least one unit floor among the other unit gradation lights 50. This is different from the light intensity P of the central portion 51 in the light control 50. For example, the light intensity P of the central portion 51 in each unit gradation light 50 becomes smaller toward the ends of the tapered holes 20 arranged in a row. Thereby, the taper angle φ of the tapered hole 20 formed by the irradiation of each unit gradation light 50 can be made substantially the same regardless of the position where each unit gradation light 50 is irradiated. As a result, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

  Further, according to the present embodiment, each modulation region 22 of the modulation mask 21 includes the modulation mask central portion 34 that modulates the light irradiated to the region where the through portion 20 a of the tapered hole 20 is formed in the workpiece 18. Contains. Each modulation mask central portion 34 is composed of a plurality of modulation unit regions 24e. Here, the radius R of the point image distribution range of the imaging optical system 17 is set to the light center wavelength λ, the emission side of the imaging optical system. When the numerical aperture NA is defined as R = 0.61λ / NA, the modulation unit conversion region obtained by converting the modulation unit region 24e into the imaging surface of the imaging optical system 17 is a point image of the imaging optical system 17. It is smaller in at least one direction than the radius of the distribution range. Each modulation unit region 24e includes: a first amplitude modulation unit region 26a that modulates light with a first amplitude modulation amount; and a second amplitude modulation unit region 26b that modulates light with a second amplitude modulation amount. It has become. The area ratio of the first amplitude modulation unit region 26a in the modulation unit region 24e of each modulation mask central portion 34 is set to a predetermined value. Therefore, each unit gradation light 50 is irradiated with the light intensity P of the central portion 51 of each unit gradation light 50 irradiated to the workpiece 18 after being modulated by each modulation region 22 of the modulation mask 21. It can be changed arbitrarily according to the position. Thereby, the taper angle φ of the tapered hole 20 formed by the irradiation of each unit gradation light 50 can be made substantially the same regardless of the position where each unit gradation light 50 is irradiated. As a result, a plurality of tapered holes 20 having substantially the same taper angle φ can be simultaneously formed in the workpiece 18.

(Modification)
In the present embodiment, an example is shown in which the area ratio of the first amplitude modulation unit region 26a in the modulation unit region 24e of each modulation mask central portion 34 is increased toward the end of the modulation mask 21. It is not limited to. According to the same technical idea as in the modification of the first embodiment shown in FIG. You may make it small as it goes to the edge.

(Other variations)
In each of the above embodiments, the laser light source 12 is an XeCl excimer laser light source 12 that supplies light having a wavelength of 308 nm. However, the present invention is not limited to this, and the laser light source 12 that supplies light having a wavelength other than 308 nm may be used as the laser light source 12. In this case, the wavelength of the laser light source 12 is determined in consideration of the material of the workpiece 18, the magnification of the imaging optical system 17, the aperture ratio NA of the imaging optical system 17, and the like.

  Moreover, in each said embodiment, the taper hole 20 which has the penetration part 20a and the inclination part 20b in the workpiece 18 by the taper hole formation apparatus 10 was shown. However, the present invention is not limited to this, and the tapered hole forming apparatus 10 may form a tapered hole 20 that does not pass through the workpiece 18, that is, a tapered hole 20 having a bottom portion and an inclined portion 20b.

  In each of the above embodiments, the modulation area 22 of the modulation mask 21 has an example of a circular outline, but the present invention is not limited to this. As long as the tapered hole 20 having a predetermined taper angle φ is formed in the workpiece 18 by the light that is modulated by the modulation region 22 and then irradiated onto the workpiece 18, the contour of the modulation region 22 is defined. It can be of any shape.

Further, in each of the above-described embodiments, the example in which the plurality of tapered holes 20 arranged in a row is formed by irradiating the workpiece 18 with each unit gradation light 50 from the tapered hole forming apparatus 10 has been described. However, the present invention is not limited to this, and for example, as shown in FIG. The light control 50 may be irradiated. In this case, as shown in FIG. 46B, a modulation mask 21 in which a plurality of modulation regions 22 each having a modulation amount distribution corresponding to the tapered hole 20 is formed is used.
The specific method of arranging the tapered holes 20 in a plurality of rows is not particularly limited, and for example, as shown in FIG. 46A, the tapered holes 20 may be arranged in a staggered pattern.

  In the present embodiment, the example in which the light modulation means 15 is configured by the modulation mask 21 and the imaging optical system 17 has been described. However, the present invention is not limited to this. The technical idea of the present invention is that, as described above, when a plurality of tapered holes are simultaneously formed in the workpiece 18, the light intensity P of the central portion 51 of each unit gradation light 50 irradiated to the workpiece 18. Alternatively, the width w of the inclined portion 52 is appropriately adjusted according to the position of the tapered hole 20. Accordingly, in the present invention, various light modulation means capable of realizing such adjustment can be used. For example, as a method of adjusting the intensity of light irradiated to the workpiece 18, a correction plate having a predetermined transmittance distribution is provided in the vicinity of the workpiece 18 or at a position conjugate with the workpiece 18. A method of giving an intensity distribution to the light irradiated to the workpiece 18 can be used.

  In the present embodiment, an example in which the plurality of tapered holes 20 formed in the workpiece each have substantially the same taper angle φ is shown. However, the present invention is not limited to this. The technical idea of the present invention is that, as described above, when a plurality of tapered holes are simultaneously formed in the workpiece 18, the light intensity P of the central portion 51 of each unit gradation light 50 irradiated to the workpiece 18. Alternatively, the width w of the inclined portion 52 is appropriately adjusted according to the position of the tapered hole 20. Therefore, in the present invention, not only the taper angle φ of each tapered hole 20 is made substantially the same, but also by adjusting the light intensity P of the central portion 51 of the unit gradation light 50 or the width w of the inclined portion 52, The taper angle φ of each tapered hole 20 can be arbitrarily set according to the position. That is, the taper angle φ of the plurality of tapered holes 20 formed in the workpiece 18 can be intentionally changed according to the position.

DESCRIPTION OF SYMBOLS 10 Tapered hole formation apparatus 11 Mask illumination system 12 Laser light source 13 Illumination optical system 15 Light modulation means 17 Imaging optical system 17a Convex lens 17b Convex lens 17c Aperture stop 17e Cylindrical 17f Imaging surface 17g Unit circle 17h Vector 17k Opening part 17l Point image Distribution range 18 Work piece 19 Mounting table 20 Tapered hole 20a Tapered hole through portion 20b Tapered hole inclined portion 20c Tapered hole distal end portion 20d Tapered hole proximal end portion 21 Modulation mask 21a Modulation mask main body portion 21b Light shielding layer 22 Modulation region 23 Non-modulation region 24e Modulation unit region 25a First phase modulation unit region 25b Second phase modulation unit region 26a First amplitude modulation unit region 26b Second amplitude modulation unit region 26c Side edge 27 Circumferential line 28a X direction side Edge 28b Y-direction side edge 29 Light shielding layer 32 Modulation mask inclined portion 33 Modulation mask peripheral edge 34 modulation mask central portion 45a first phase modulation unit region 45b second phase modulation unit region 50 unit gradation light 51 central portion 52 inclined portion 53 peripheral portion 100 conventional laser processing apparatus 102 laser light source 103 illumination optical system 104 mask 105 quartz Glass layer 106 Light shielding film 106a Opening 107 Imaging optical system 108 Work piece 109 Stage 110 Nozzle 110b Nozzle taper

Claims (23)

Tapered hole formation that modulates the light emitted from the light source and irradiates the workpiece with the modulated light to form a plurality of tapered holes having a through portion or a bottom portion and a tapered portion in the workpiece. In the device
A light source that emits light;
A light modulation means that is provided on the emission side of the light source, modulates the light from the light source, and irradiates the workpiece with light,
The light modulation means has a plurality of unit modulation means each having a modulation amount distribution corresponding to a tapered hole,
The light that is modulated by each unit modulation means and applied to the workpiece is unit gradation light having a light intensity distribution corresponding to the tapered hole,
Each unit gradation light is positioned at the central portion irradiated to the region where the through-hole or bottom portion of the tapered hole is formed in the workpiece, and at the outer edge of the central portion. Including an inclined portion that is irradiated to a region where the portion is formed and whose light intensity decreases toward the outside, and a peripheral portion located at an outer edge of the inclined portion,
The width of the inclined portion in one unit gradation light among each unit gradation light is different from the width of the inclined portion in at least one unit gradation light among the other unit gradation lights ,
The unit gradation light is applied to the workpiece such that each unit gradation light is arranged in a row or a plurality of rows on the workpiece,
The tapered hole forming apparatus, wherein the width of the inclined portion in each unit gradation light increases toward the end of the column . Tapered hole formation that modulates the light emitted from the light source and irradiates the workpiece with the modulated light to form a plurality of tapered holes having a through portion or a bottom portion and a tapered portion in the workpiece. In the device
A light source that emits light;
A light modulation means that is provided on the emission side of the light source, modulates the light from the light source, and irradiates the workpiece with light,
The light modulation means has a plurality of unit modulation means each having a modulation amount distribution corresponding to a tapered hole,
The light that is modulated by each unit modulation means and applied to the workpiece is unit gradation light having a light intensity distribution corresponding to the tapered hole,
Each unit gradation light is positioned at the central portion irradiated to the region where the through-hole or bottom portion of the tapered hole is formed in the workpiece, and at the outer edge of the central portion. Including an inclined portion that is irradiated to a region where the portion is formed and whose light intensity decreases toward the outside, and a peripheral portion located at an outer edge of the inclined portion,
The width of the inclined portion in one unit gradation light among each unit gradation light is different from the width of the inclined portion in at least one unit gradation light among the other unit gradation lights ,
The unit gradation light is applied to the workpiece such that each unit gradation light is arranged in a row or a plurality of rows on the workpiece,
A tapered hole forming apparatus, wherein the width of the inclined portion in each unit gradation light is reduced toward the end of the column . Tapered hole formation that modulates the light emitted from the light source and irradiates the workpiece with the modulated light to form a plurality of tapered holes having a through portion or a bottom portion and a tapered portion in the workpiece. In the device
A light source that emits light;
A modulation mask that is provided on the emission side of the light source and modulates and emits the light from the light source;
An imaging optical system that is provided on the emission side of the modulation mask and forms an image of light modulated by the modulation mask and irradiates the workpiece;
The modulation mask has a plurality of modulation regions each having a modulation amount distribution corresponding to a tapered hole,
Each modulation region is located at the center of the modulation mask that modulates the light irradiated to the region where the through-hole or bottom portion of the tapered hole is formed in the workpiece, and at the outer edge of the center of the modulation mask. A modulation mask inclined portion that modulates light irradiated to a region where the tapered portion of the tapered hole is formed, and a modulation mask peripheral portion located at an outer edge of the modulation mask inclined portion,
Each modulation mask inclined part consists of a plurality of modulation unit regions,
When the radius R of the point image distribution range of the imaging optical system is defined as R = 0.61λ / NA using the central wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system, the modulation unit The modulation unit conversion area in which the area is converted into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system,
Each modulation unit region includes a first modulation unit region that modulates light with a first modulation amount, and a second modulation unit region that modulates light with a second modulation amount,
The occupancy of the first modulation unit region in each modulation unit region of the modulation mask inclined part monotonously increases or decreases toward the outside of the modulation region,
A taper hole forming apparatus, wherein a width of a modulation mask inclined portion in one modulation region of each modulation region is different from a width of a modulation mask inclination portion in at least one modulation region of other modulation regions. The modulation areas are arranged such that each modulation area is arranged in a line or a plurality of lines on the modulation mask,
4. The tapered hole forming apparatus according to claim 3 , wherein the width of the modulation mask inclined portion in each modulation region increases toward the end of the column. 5. The tapered hole forming apparatus according to claim 4 , wherein in the modulation mask inclined portion, the number of the modulation unit regions arranged in the width direction of the modulation mask inclined portion increases toward the end of the row. 5. The tapered hole formation according to claim 4 , wherein, in the modulation mask inclined portion, the dimension in the width direction of the modulation unit region arranged in the width direction of the modulation mask inclined portion increases toward the end of the row. apparatus. The modulation areas are arranged such that each modulation area is arranged in a line or a plurality of lines on the modulation mask,
4. The tapered hole forming apparatus according to claim 3 , wherein the width of the inclined portion of the modulation mask in each modulation region becomes smaller toward the end of the row. 8. The tapered hole forming apparatus according to claim 7 , wherein in the modulation mask inclined portion, the number of the modulation unit regions arranged in the width direction of the modulation mask inclined portion decreases toward the end of the row. 8. The tapered hole forming device according to claim 7 , wherein in the modulation mask inclined portion, the dimension in the width direction of the modulation unit region arranged in the width direction of the modulation mask inclined portion becomes smaller toward the end of the row. . The first modulation amount of the first modulation unit region and the second modulation amount of the second modulation unit region are predetermined phase modulation amounts different from each other by an odd multiple of 180 degrees,
In the modulation mask inclined portion, the difference between the occupancy rate of the first modulation unit region and the occupancy rate of the inclined portion second modulation region in each modulation unit region monotonously decreases toward the outside of the modulation mask inclined portion. The taper hole forming device according to claim 3 , wherein the taper hole forming device comprises: The first modulation unit region includes a light shielding layer that shields light;
In the modulation mask inclined section, the occupancy of the first modulation unit area in each modulation unit region, any one of claims 3 to 9, characterized in that monotonically increases toward the outside of the modulating mask inclined portion A tapered hole forming apparatus according to claim 1. Tapered hole formation that modulates the light emitted from the light source and irradiates the workpiece with the modulated light to form a plurality of tapered holes having a through portion or a bottom portion and a tapered portion in the workpiece. In the method
Preparing a light source for emitting light;
A step of modulating light from the light source by a modulation mask provided on the emission side of the light source;
A step of forming an image of light modulated by the modulation mask and irradiating the workpiece with an imaging optical system provided on the emission side of the modulation mask; and
The modulation mask has a plurality of modulation regions each having a modulation amount distribution corresponding to a tapered hole,
Each modulation region is located at the center of the modulation mask that modulates the light irradiated to the region where the through-hole or bottom portion of the tapered hole is formed in the workpiece, and at the outer edge of the center of the modulation mask. A modulation mask inclined portion that modulates light irradiated to a region where the tapered portion of the tapered hole is formed, and a modulation mask peripheral portion located at an outer edge of the modulation mask inclined portion,
Each modulation mask inclined part consists of a plurality of modulation unit regions,
When the radius R of the point image distribution range of the imaging optical system is defined as R = 0.61λ / NA using the central wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system, the modulation unit The modulation unit conversion area in which the area is converted into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system,
Each modulation unit region includes a first modulation unit region that modulates light with a first modulation amount, and a second modulation unit region that modulates light with a second modulation amount,
The occupancy of the first modulation unit region in each modulation unit region of the modulation mask inclined part monotonously increases or decreases toward the outside of the modulation region,
A taper hole forming method, wherein a width of a modulation mask inclined portion in one modulation region of each modulation region is different from a width of a modulation mask inclination portion in at least one modulation region of other modulation regions. Provided between a light source that emits light and an imaging optical system that forms an image of light and irradiates the workpiece, and modulates the light from the light source and applies the modulated light to the imaging optical system. In the modulation mask that emits toward
A plurality of tapered holes having a penetrating portion or a bottom portion and a tapered portion are formed in the workpiece by light irradiated on the workpiece from the imaging optical system,
The modulation mask has a plurality of modulation regions each having a modulation amount distribution corresponding to the taper hole, and each modulation region is irradiated to a region where a through-hole or a bottom portion of the taper hole is formed in the workpiece. A modulation mask central portion that modulates light; a modulation mask inclined portion that modulates light irradiated on a region where a tapered portion of a tapered hole is formed in the workpiece; A modulation mask peripheral edge located at the outer edge of the modulation mask inclined portion, and
Each modulation mask inclined part consists of a plurality of modulation unit regions,
When the radius R of the point image distribution range of the imaging optical system is defined as R = 0.61λ / NA using the central wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system, the modulation unit The modulation unit conversion area in which the area is converted into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system,
Each modulation unit region includes a first modulation unit region that modulates light with a first modulation amount, and a second modulation unit region that modulates light with a second modulation amount,
The occupancy of the first modulation unit region in each modulation unit region of the modulation mask inclined part monotonously increases or decreases toward the outside of the modulation region,
The modulation mask characterized in that the width of the modulation mask inclined portion in one modulation region of each modulation region is different from the width of the modulation mask inclination portion in at least one modulation region of the other modulation regions. Tapered hole formation that modulates the light emitted from the light source and irradiates the workpiece with the modulated light to form a plurality of tapered holes having a through portion or a bottom portion and a tapered portion in the workpiece. In the device
A light source that emits light;
A light modulation means that is provided on the emission side of the light source, modulates the light from the light source, and irradiates the workpiece with light,
The light modulation means has a plurality of unit modulation means each having a modulation amount distribution corresponding to a tapered hole,
The light that is modulated by each unit modulation means and applied to the workpiece is unit gradation light having a light intensity distribution corresponding to the tapered hole,
Each unit gradation light is positioned outside the central portion and irradiated to the region where the through-hole or bottom portion of the tapered hole is formed in the workpiece, and the tapered hole tapers in the workpiece. A peripheral portion irradiated to the peripheral region of the region where the portion is formed,
The light intensity of the central part of one unit gradation light among the unit gradation lights is different from the light intensity of the central part of at least one unit gradation light of the other unit gradation lights .
The unit gradation light is applied to the workpiece such that each unit gradation light is arranged in a row or a plurality of rows on the workpiece,
A taper hole forming apparatus characterized in that the light intensity at the central portion of each unit gradation light decreases toward the end of the column . Tapered hole formation that modulates the light emitted from the light source and irradiates the workpiece with the modulated light to form a plurality of tapered holes having a through portion or a bottom portion and a tapered portion in the workpiece. In the device
A light source that emits light;
A light modulation means that is provided on the emission side of the light source, modulates the light from the light source, and irradiates the workpiece with light,
The light modulation means has a plurality of unit modulation means each having a modulation amount distribution corresponding to a tapered hole,
The light that is modulated by each unit modulation means and applied to the workpiece is unit gradation light having a light intensity distribution corresponding to the tapered hole,
Each unit gradation light is positioned outside the central portion and irradiated to the region where the through-hole or bottom portion of the tapered hole is formed in the workpiece, and the tapered hole tapers in the workpiece. A peripheral portion irradiated to the peripheral region of the region where the portion is formed,
The light intensity of the central part of one unit gradation light among the unit gradation lights is different from the light intensity of the central part of at least one unit gradation light of the other unit gradation lights .
The unit gradation light is applied to the workpiece such that each unit gradation light is arranged in a row or a plurality of rows on the workpiece,
A taper hole forming device characterized in that the light intensity at the central portion of each unit gradation light increases toward the end of the column . Tapered hole formation that modulates the light emitted from the light source and irradiates the workpiece with the modulated light to form a plurality of tapered holes having a through portion or a bottom portion and a tapered portion in the workpiece. In the device
A light source that emits light;
A modulation mask that is provided on the emission side of the light source and modulates and emits the light from the light source;
An imaging optical system that is provided on the emission side of the modulation mask and forms an image of light modulated by the modulation mask and irradiates the workpiece;
The modulation mask has a plurality of modulation regions each having a modulation amount distribution corresponding to a tapered hole,
Each modulation region is located at the center of the modulation mask that modulates the light applied to the region where the through-hole or bottom portion of the tapered hole is formed in the workpiece, and outside the center portion of the modulation mask. A modulation mask peripheral portion that modulates light applied to the peripheral region of the region where the tapered portion of the tapered hole is formed,
Each modulation mask central portion is composed of a plurality of modulation unit regions,
When the radius R of the point image distribution range of the imaging optical system is defined as R = 0.61λ / NA using the central wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system, the modulation unit The modulation unit conversion area in which the area is converted into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system,
Each modulation unit region includes a first modulation unit region that modulates light with a first modulation amount, and a second modulation unit region that modulates light with a second modulation amount,
The occupancy of the first modulation unit area in the modulation unit area at the center of each modulation mask is set to a predetermined value,
The occupancy ratio of the first modulation unit area at the center of the modulation mask in one modulation area among the modulation areas is the occupancy ratio of the first modulation unit area at the center of the modulation mask in at least one of the other modulation areas. A taper hole forming device characterized by being different from the above. The modulation areas are arranged such that each modulation area is arranged in a line or a plurality of lines on the modulation mask,
The taper hole forming device according to claim 16 , wherein the occupation ratio of the first modulation unit area at the center of the modulation mask in each modulation area monotonously increases or decreases toward the end of the column. The first modulation amount of the first modulation unit region and the second modulation amount of the second modulation unit region are predetermined phase modulation amounts different from each other by an odd multiple of 180 degrees,
The difference between the occupancy and the occupancy of the second modulation unit area of the first modulation unit area in the modulation mask central portion of each modulation region, to claim 17, characterized in that monotonically decreases toward the end of the column The taper hole forming apparatus described. The first modulation amount of the first modulation unit region and the second modulation amount of the second modulation unit region are predetermined phase modulation amounts different from each other by an odd multiple of 180 degrees,
The difference between the occupancy of the occupancy rate and the second modulation unit area of the first modulation unit area in the modulation mask central portion of each modulation region, to claim 17, wherein the monotonically increasing toward the end of the column The taper hole forming apparatus described. The first modulation unit region includes a light shielding layer that shields light;
18. The tapered hole forming apparatus according to claim 17 , wherein the occupation ratio of the first modulation unit region in the modulation mask central portion of each modulation region monotonously increases toward the end of the column. The first modulation unit region includes a light shielding layer that shields light;
18. The tapered hole forming device according to claim 17 , wherein the occupation ratio of the first modulation unit region in the modulation mask central portion of each modulation region is monotonously decreased toward the end of the row. Tapered hole formation that modulates the light emitted from the light source and irradiates the workpiece with the modulated light to form a plurality of tapered holes having a through portion or a bottom portion and a tapered portion in the workpiece. In the method
Preparing a light source for emitting light;
A step of modulating light from the light source by a modulation mask provided on the emission side of the light source;
A step of forming an image of light modulated by the modulation mask and irradiating the workpiece with an imaging optical system provided on the emission side of the modulation mask; and
The modulation mask has a plurality of modulation regions each having a modulation amount distribution corresponding to a tapered hole,
Each modulation region is located at the center of the modulation mask that modulates the light applied to the region where the through-hole or bottom portion of the tapered hole is formed in the workpiece, and outside the center portion of the modulation mask. A modulation mask peripheral portion that modulates light applied to the peripheral region of the region where the tapered portion of the tapered hole is formed,
Each modulation mask central portion is composed of a plurality of modulation unit regions,
When the radius R of the point image distribution range of the imaging optical system is defined as R = 0.61λ / NA using the central wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system, the modulation unit The modulation unit conversion area in which the area is converted into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system,
Each modulation unit region includes a first modulation unit region that modulates light with a first modulation amount, and a second modulation unit region that modulates light with a second modulation amount,
The occupancy of the first modulation unit area in the modulation unit area at the center of each modulation mask is set to a predetermined value,
The occupation ratio of the first modulation unit area at the center of the modulation mask in one modulation area among the modulation areas is the occupation ratio of the first modulation unit area at the center of the modulation mask in at least one modulation area among the other modulation areas. A method for forming a tapered hole, which is different from FIG. Provided between a light source that emits light and an imaging optical system that forms an image of light and irradiates the workpiece, and modulates the light from the light source and applies the modulated light to the imaging optical system. In the modulation mask that emits toward
A plurality of tapered holes having a penetrating portion or a bottom portion and a tapered portion are formed in the workpiece by light irradiated on the workpiece from the imaging optical system,
The modulation mask has a plurality of modulation regions each having a modulation amount distribution corresponding to the taper hole, and each modulation region is irradiated to a region where a through-hole or a bottom portion of the taper hole is formed in the workpiece. Modulation mask central part for modulating light and modulation mask peripheral part located outside the modulation mask central part and for modulating the light irradiated to the peripheral area of the taper part of the tapered hole in the workpiece And
Each modulation mask central portion is composed of a plurality of modulation unit regions,
When the radius R of the point image distribution range of the imaging optical system is defined as R = 0.61λ / NA using the central wavelength λ of light and the numerical aperture NA on the exit side of the imaging optical system, the modulation unit The modulation unit conversion area in which the area is converted into the imaging plane of the imaging optical system is smaller in at least one direction than the radius of the point image distribution range of the imaging optical system,
Each modulation unit region includes a first modulation unit region that modulates light with a first modulation amount, and a second modulation unit region that modulates light with a second modulation amount,
The occupancy of the first modulation unit area in the modulation unit area at the center of each modulation mask is set to a predetermined value,
The occupation ratio of the first modulation unit area at the center of the modulation mask in one modulation area among the modulation areas is the occupation ratio of the first modulation unit area at the center of the modulation mask in at least one modulation area among the other modulation areas. Modulation mask characterized by being different from

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