JP2008089818A - Photomask and method for manufacturing silicon bench using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the efficiency of a manufacturing process of a silicon bench, to reduce the time of the manufacturing process and to improve the accuracy of manufacturing, by reducing the cost of a photolithography process and simplifying processes of forming grooves, dicing or the like. <P>SOLUTION: After a resist pattern having a plurality of figures and thickness is formed through a developing process in a resist layer formed on a silicon substrate by using a photomask, the resist pattern on the silicon substrate is used as a mask to etch the surface of the silicon substrate at one time into the same figure as the resist pattern. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a silicon bench for mounting optical components used in an optical communication system.

  A silicon bench on which optical components used in an optical communication system are mounted is used as a substrate for mounting a laser diode, a light receiving diode, a lens, an optical fiber, and the like. As such a silicon bench, one in which one groove and an electrode are conventionally formed is known (for example, see Patent Document 1).

  However, according to the method for manufacturing a silicon bench disclosed in Patent Document 1, when a silicon bench having a plurality of grooves is manufactured, it is necessary to perform a plurality of etching and dicing steps. For example, V-grooves of different sizes on which optical fibers, lenses, etc. are mounted are produced by multiple photolithography and multiple wet etching processes with an alkaline solution such as KOH, and further intersect at the center of the substrate surface. The separation groove is formed by dicing.

On the other hand, a method of manufacturing using a mask having a gray gradation (referred to as a gray mask) without using such a plurality of photolithography steps and etching steps has been proposed (see, for example, Patent Document 2). .
JP 2005-25172 A Japanese Patent No. 3117886

  However, the gray mask disclosed in Patent Document 2 for this silicon bench is expensive, and has not been used in a manufacturing process that requires a low price such as a silicon bench manufacturing process.

  In addition, in the conventional silicon bench fabrication process, photolithography, etching, dicing, etc. that are repeated multiple times are performed, so that the accuracy of the position of each pattern to be processed is lowered and the cost is increased due to the complexity of the processing process. Etc. occurred. Further, when a silicon substrate having a (100) plane orientation is used as the substrate material for the silicon bench, when the V-groove is formed by the wet etching process, the angle of the V-groove is fixed at a constant angle (54 degrees). Therefore, it is extremely difficult to form an arbitrary angle.

  In view of this, the inventor of the present application has conducted extensive research and found that grooves having different depths and V-grooves are formed on a common silicon substrate. Therefore, resists having different thicknesses are required to form these grooves. It has been found that the conventional problems can be solved by using a photomask capable of projecting a latent image of a groove having a different depth or a groove having a varying depth on the resist layer, that is, the resist layer.

  Therefore, the present invention is to solve the above-mentioned economic and technical problems, and its purpose is to reduce the cost of the photolithography process and simplify the processes such as groove processing and dicing, thereby producing a silicon bench. The purpose is to improve process efficiency, shorten process time, and improve manufacturing accuracy.

  The first photomask of the first invention has the following characteristics.

  The first photomask is an exposure photomask for forming a resist pattern having a non-uniform film thickness. The first photomask is composed of a transparent mask substrate and a close contact with the mask substrate. And a plurality of square mask cells arranged in this manner. The length of one side of the mask cell is set to be shorter than the length that becomes the resolution limit of the optical system of the exposure apparatus in which the first photomask is used.

  In addition, this mask cell has one or both of a light transmission region and a light shielding region formed by a light shielding film provided on the mask substrate. It is the chemical light intensity. The light intensity of the transmitted light is determined by the area ratio of the light transmission region to the mask cell.

  Further, a first rectangular area and a second rectangular area are defined in a planar area when the first photomask is viewed from above, and the first mask cell group included in the first rectangular area includes the first light mask. The second mask cell group having an intensity (where 0 <first light intensity <1) and included in the second rectangular region has a second light intensity (where first light intensity <second light intensity ≦ And the remaining third mask cell group outside the first and second rectangular regions has a third light intensity (where 0 ≦ third light intensity <1). ing.

  The second photomask of the second invention has the following characteristics. The second photomask is an exposure photomask for forming a resist pattern having a non-uniform film thickness. The second photomask is composed of a transparent mask substrate and a mask substrate. And a plurality of square mask cells arranged closely. The length of one side of the mask cell is set to be shorter than the length that becomes the resolution limit of the optical system of the exposure apparatus in which the second photomask is used.

  In addition, this mask cell has one or both of a light transmission region and a light shielding region formed by a light shielding film provided on the mask substrate. It is the chemical light intensity. The light intensity of the transmitted light is determined by the area ratio of the light transmission region to the mask cell.

  Furthermore, the first rectangular region and the second rectangular region are partitioned in the planar region when the second photomask is viewed from above, and the first mask cell group included in the first rectangular region includes the first light cell. The second mask cell group having intensity (however, 0 <first light intensity <1) and included in the second rectangular area has a second light intensity on two sides in the longitudinal direction of the second rectangular area. (Where 0 ≦ second light intensity <first light intensity), and a third light intensity greater than the second light intensity on the center line in the longitudinal direction (however, second light intensity <third Light intensity <1, and between the two sides and the center line, the light intensity linearly changes from the second light intensity to the third light intensity, and The remaining third mask cell groups outside the first and second rectangular regions have the second light intensity.

  A third invention is a method for manufacturing a silicon bench using the photomask for forming a resist pattern according to the first or second invention, and the method is provided on a silicon substrate using the photomask. After forming a resist pattern with multiple shapes and thickness on the formed resist layer by the development process, the surface of the silicon substrate is etched in a batch with the same shape as the resist pattern using the resist pattern on the silicon substrate as a mask It has the feature in the point to do.

  Furthermore, a fourth invention is a method for manufacturing a silicon bench according to the third invention, wherein a separation groove, a V-groove for component placement, and a component having different depth shapes are formed on the surface of the silicon substrate. It is characterized in that an alignment mark for placement is formed at the same time.

  According to the first invention, the first photomask for exposure for forming a resist pattern having a non-uniform film thickness is the first photomask in the plane area when the first photomask is viewed from above. A rectangular area and a second rectangular area are partitioned, and the first mask cell group and the second mask cell group included in the two rectangular areas respectively have a first light intensity and a second light intensity (where 0 <first Light intensity <second light intensity ≦ 1). Therefore, two vertical groove-shaped resist patterns having arbitrary rectangular regions of different sizes are formed, each having a rectangular region having an arbitrary size, and the second rectangular region being deeper than the first rectangular region. Therefore, an effect is obtained that a first photomask is obtained.

  Further, according to the second invention, the second photomask for exposure for forming a resist pattern having a non-uniform film thickness is in a plane region when the second photomask is viewed from above. The first rectangular area and the second rectangular area are partitioned, and the first mask cell group included in the first rectangular area has the first light intensity (where 0 <first light intensity <1). is doing. The second mask cell group included in the second rectangular region has the second light intensity (where 0 ≦ second light intensity <first light intensity) on the two sides in the longitudinal direction of the second rectangular region. And has a third light intensity greater than the second light intensity (where the second light intensity <the third light intensity <1) on the longitudinal center line, and the two sides Between the center line, the light intensity linearly changes from the second light intensity to the third light intensity. Therefore, according to the second invention, one vertical groove-shaped resist pattern having an arbitrary size and depth formed in the first rectangular region and an arbitrary angle and depth formed in the second rectangular region. There is an effect that a second photomask for forming a single V-groove resist pattern having the above can be obtained.

  According to the third invention, by using the photomask for forming a resist pattern of the first or second invention, a silicon bench similar to the conventional one can be produced by performing only one photolithography and etching process. Is possible. Conventionally, the end portion of the V-groove is an inclined surface, and this portion may be an obstacle to the arrangement of the optical fiber. However, according to the present invention, a vertical structure or a structure of an arbitrary angle is used. Therefore, there is an effect that there is no obstacle in arranging the optical fiber or the like.

  Further, according to the fourth aspect of the present invention, the separation grooves, the component placement V-grooves, and the component placement alignment marks, each having a different depth shape, can be formed by a single etching process with photomask fabrication accuracy. Since it can be formed, alignment and mounting for component mounting can be performed with high accuracy, and the silicon bench can be provided at a low price.

  Embodiments of the present invention will be described below with reference to the drawings. The drawings only schematically show the shapes, sizes, and arrangement relationships of the components to the extent that the present invention can be understood, and the numerical and other conditions described below are merely preferred examples. The present invention is not limited to the embodiments of the present invention. In the figure, in order to prevent complication of the figure, hatching representing a cross section is partially omitted.

(First Embodiment: Photomask)
With reference to FIGS. 1A, 1B, and 1C, a photomask for forming a resist pattern according to the present invention will be described. FIG. 1A, FIG. 1B, and FIG. 1C are schematic views for explaining a photomask. FIG. 1A is a schematic plan view of a part of the photomask as viewed from above. FIG. 1B is a diagram showing a cross section cut along a plane along line AA in FIG. FIG. 1C is a diagram for explaining the relationship between the position in the direction (X direction) along the line AA in FIG. 1A and the light intensity of the transmitted light. In FIG. 1C, the horizontal axis indicates the position in the X direction, and the vertical axis indicates the light intensity of the transmitted light.

  The photomask 10 includes a plurality of square mask cells 40 having the same size on a transparent mask substrate 20 such as quartz glass. The mask cell 40 is set in a plurality of unit mask cell regions defined on one main surface of the mask substrate 20. These unit mask cell regions are a plurality of virtual grid lines 46 that are straight lines drawn in the X direction (or row direction) and the Y direction (or column direction) orthogonal to each other, and are formed on one main surface of the mask substrate 20. This is an area set by being equally spaced. Therefore, these unit mask cell areas are arranged as an orthogonal matrix (matrix) arrangement.

  In the mask cell 40, either one or both of the light transmission region 44 and the light shielding region 42 are set. A light shielding film 30 is formed in the light shielding region 42 on the mask substrate 20 by, for example, vapor deposition of chromium. The mask cell 40 is a basic unit for controlling the light intensity transmitted through the photomask 10. In the case of the mask cell 40 having the same area, the intensity of light transmitted through the mask cell 40 is given by the area ratio of the light transmission region 44 to the mask cell 40. That is, the larger the area of the light transmission region 44 in the mask cell 40, the greater the intensity of light transmitted through the mask cell 40 (FIG. 1C).

  The light intensity of the transmitted light of the mask cell 40 can be a normalized light intensity. That is, the standardized light intensity is a value of the intensity of light transmitted through another mask cell determined by setting the maximum light intensity as 1 when the intensity of light transmitted through one of the mask cells is the maximum among the many mask cells. It is. Accordingly, the normalized light intensity takes any value between 1 and 0. Each mask cell is assigned a normalized light intensity determined by design.

  In FIG. 1A, the mask cell 40 in which both the light transmission region 44 and the light shielding region 42 are set is bisected by a virtual bisector 48 in the Y direction, and one side of the virtual bisector 48 (in the drawing). In the example, the light transmission region 44 is set on the right side of the virtual bisector, and the light shielding region 42 is set on the other side (left side of the virtual bisector in the drawing). For each mask cell, the light transmission region 44 is preferably set on the same side with respect to the virtual bisector 48. This is due to the following reason.

  When the target resist pattern shape is a curved surface whose thickness changes continuously, mask cells 40 having the same light intensity are set continuously in a region where the change in thickness of the resist layer is gradual. Sometimes. For each mask cell 40, when the light transmission region 44 is set on the same side with respect to the virtual bisector 48, for the mask cells 40 having the same light intensity provided continuously in the Y direction, the light shielding region is Configured as one rectangle. As the number of rectangles constituting the mask pattern increases or decreases, both the data and the amount necessary for generating the mask pattern increase and decrease. Therefore, if the light shielding film 30 of each mask cell 40 is collectively formed as one rectangle, the amount of data necessary for generating the mask pattern can be reduced. As a result, the time required for manufacturing the photomask can be shortened and the cost can be reduced.

  1A and 1B show an example in which the light transmission region 44 and the light shielding region 42 are set for all the mask cells 40, but the present invention is not limited to this example. That is, the photomask may include a mask cell in which only the light transmission region 44 is set, that is, a mask cell without the light shielding region 42, or a mask cell in which only the light shielding region 42 is set in the mask cell 40, that is, a mask cell without the light transmission region 44. good. Here, the width of the light transmission region (space) 44 is D, and the width of the light shielding region (line) 42 is W.

  The length of one side of the mask cell 40 (hereinafter also referred to as a mask pitch) P is set to be shorter than the length that is the resolution limit of the optical system of the exposure apparatus in which the photomask 10 is used. For this reason, when the resist is exposed using the photomask 10, a contrast sufficient to resolve the mask pattern of the photomask cannot be obtained. When the resist is exposed using the photomask 10 and then developed, the thickness of the resist changes continuously without separation.

  Therefore, as described above, according to the photomask for forming a resist pattern, the light intensity transmitted for each mask cell can be set.

  Next, a first photomask according to the first aspect of the present invention will be described with reference to FIGS. 2 (A), 2 (B) and 2 (C). 2A, 2B, and 2C are schematic diagrams for explaining the first photomask. FIG. 2A is a schematic plan view seen from above the first photomask 100. FIG. 2B is a diagram showing a cross-sectional view taken along a plane along line BB in FIG. FIG. 2C is a diagram for explaining the relationship between the position in the direction (X direction) along the line BB and the light intensity of the transmitted light. In FIG. 2C, the horizontal axis indicates the position in the X direction, and the vertical axis indicates the light intensity of the transmitted light.

  The first photomask 100 has a first rectangular region 110 and a second rectangular region 120 that are partitioned on a transparent mask substrate 102 such as quartz glass. In this embodiment, as an example, mask cells are set in a matrix array of 4 rows and 11 columns in the first rectangular area 110, while mask cells are set in a matrix array of 6 rows and 11 columns in the second rectangular area 120. However, the present invention is not limited to these sequences.

  The first mask cell group 112 made up of a plurality of mask cells included in the first rectangular region 110 is composed of a set of mask cells having the same light intensity, that is, a light transmitting region that transmits light having the first light intensity. ing. The normalized light intensity of the first light intensity has a light intensity of 0 <first light intensity <1.

  The second mask cell group 122 including a plurality of mask cells included in the second rectangular region 120 has a light transmission region that transmits light having a light intensity different from the first light intensity, that is, light having the second light intensity. It consists of a collection of identical mask cells. The normalized light intensity of the second light intensity has a light intensity of first light intensity <second light intensity ≦ 1.

  Furthermore, the third mask cell group 132 in the region 130 other than the first and second rectangular regions is the same mask cell having a light transmission region that transmits light having a third light intensity different from the first and second light intensities. It consists of a collection. The normalized light intensity of the third light intensity has a light intensity of 0 ≦ third light intensity <1. In this embodiment, the third light intensity = 0, and this area is a light shielding area.

  FIG. 2C is a diagram showing the light intensity distribution of the transmitted light in the first and second rectangular regions of the photomask. The light intensity of the transmitted light in the first rectangular region 110 is constant and is the first light intensity. The light intensity of the transmitted light in the second rectangular area is the second light intensity (greater than the first light intensity) and is constant. The light intensity of the transmitted light outside the first and second rectangular regions is the third light intensity, which is constant and the light intensity is zero.

  Therefore, when the photomask pattern is projected onto the resist layer using the photomask 100 to be exposed, and then the resist layer is developed, a partitioned first rectangular region 110 and second rectangular region 120 are formed, It is possible to obtain a resist pattern having two longitudinal groove shape patterns having different depths according to light intensity, in which the second rectangular region is deeper than the first rectangular region.

  Next, a second photomask according to the second aspect of the present invention will be described with reference to FIGS. 3 (A), 3 (B) and 3 (C). FIG. 3A, FIG. 3B, and FIG. 3C are schematic diagrams for explaining the second photomask. FIG. 3A is a schematic plan view seen from above the second photomask 200. FIG. 3B is a diagram showing a cross-sectional view taken along a plane along line CC in FIG. FIG. 3C is a diagram for explaining the relationship between the position in the direction (X direction) along the line CC and the light intensity of the transmitted light. In FIG. 3C, the horizontal axis indicates the position in the X direction, and the vertical axis indicates the light intensity of the transmitted light.

  The second photomask 200 has a first rectangular region 210 and a second rectangular region 220 that are partitioned on a transparent mask substrate 202 such as quartz glass. In this embodiment, as an example, mask cells are set in a matrix array of 4 rows and 11 columns in the first rectangular area 210, while mask cells are set in a matrix array of 7 rows and 11 columns in the second rectangular area 220. However, the present invention is not limited to these sequences.

  The first mask cell group 212 made up of a plurality of mask cells included in the first rectangular region 210 is composed of an aggregate of mask cells having light transmission regions that transmit light having the same light intensity, that is, the first light intensity. ing. The normalized light intensity of the first light intensity has a light intensity of 0 <first light intensity <1.

  In addition, the configuration of the second mask cell group 222 composed of a plurality of mask cells included in the second rectangular region 220 has the second light intensity (however, the normalized light intensity on the two sides in the longitudinal direction of the second rectangular region). 0 ≦ second light intensity <first light intensity). On the center line in the longitudinal direction, the second light intensity is larger than the second light intensity (however, the normalized light intensity is second light intensity <third light intensity <1). Between the two sides in the longitudinal direction of the rectangular region and the center line, the light intensity linearly changes from the second light intensity to the third light intensity.

  Further, the third mask cell group 232 in the region 230 other than the first and second rectangular regions is composed of an aggregate of the same mask cells having a light transmission region that transmits light having the second light intensity. The normalized light intensity of the second light intensity has a light intensity of 0 ≦ second light intensity <1. In this embodiment, the second light intensity = 0, and this area is a light shielding area.

  FIG. 3C is a diagram showing the light intensity distribution of the transmitted light in the first and second rectangular regions of the photomask. The light intensity of the transmitted light in the first rectangular region 210 is constant and is the first light intensity. Further, the light intensity of the transmitted light in the second rectangular area is the second light intensity on the two sides in the longitudinal direction of the second rectangular area (however, the normalized light intensity is 0 ≦ second light intensity <first Light intensity). On the center line in the longitudinal direction, the second light intensity is larger than the second light intensity (however, the normalized light intensity is second light intensity <third light intensity <1). Between the two sides in the longitudinal direction of the rectangular region and the center line, the light intensity linearly changes from the second light intensity to the third light intensity. The light intensity of the transmitted light in the regions outside the first and second rectangular regions is the second light intensity, which is constant and the light intensity is zero.

  Accordingly, when the resist layer is exposed using the photomask 200 to form a latent image of the photomask pattern and is developed by developing the resist layer, the partitioned first rectangular region 210 and second rectangular region 220 are formed. One vertical groove-shaped resist pattern having an arbitrary size and depth formed in the first rectangular region and one V-groove shape having an arbitrary angle and depth formed in the second rectangular region This resist pattern can be obtained.

Second Embodiment: Silicon Bench Manufacturing Method Using a Photomask (Part 1)
As an example of a silicon bench manufacturing method for explaining the third invention of the present invention, an example of manufacturing a silicon bench 300 as shown in FIG. 4 will be described. In FIG. 4, FIG. 4A is a plan view seen from the top surface of the silicon bench 300. The silicon bench 300 has a rectangular shape as a whole, and a separation groove 302 that intersects the center of the rectangle at right angles, and a V-groove 304 that is shallower than the separation groove 302. It is composed of FIG. 4B is a side view of one end face of the silicon bench 300 viewed from the A direction. A V-groove 304 is formed on the left side of the separation groove 302. The size of the separation groove 302 and the V groove 304 is 100 μm in width, 200 μm in depth, 150 μm in width, and 103 μm in depth, respectively.

  The silicon bench 300 having the above shape is manufactured. The silicon substrate used is 6 inches in diameter. The applied resist thickness is 3.5 μm, and the resist is a positive type resist (for example, trade name IX410 manufactured by JSR Corporation) applied by a spin coater. The exposure apparatus uses an i-line (wavelength λ = 365 nm) stepper (for example, product name NSR-2205i11D manufactured by Nikon), and the exposure conditions are numerical aperture NA = 0.5, coherence factor σ = 0.5. The reduction projection magnification was set to 5 times. Further, the length of one side of the mask cell 40 in FIG. 1B, that is, the mask pitch P is set to 400 nm.

  With reference to FIG. 5, the mask pattern arrangement procedure of the photomask will be described. In order to determine the arrangement of the mask pattern, a relationship between the space width of the mask cell and the film thickness of the remaining resist layer (hereinafter simply referred to as resist film thickness) is required. FIG. 5 is a diagram showing the resist film thickness remaining after exposure and development with respect to the space width (see FIG. 1B), and shows the resist film thickness at an exposure time of 280 milliseconds. In FIG. 5, the horizontal axis represents the space width (unit: nm) of the mask cell, and the vertical axis represents the remaining resist film thickness (unit: μm) after exposure and development.

  According to the characteristic curve shown in FIG. 5, a resist film thickness of 3.5 μm is obtained with a space width of 120 nm, that is, a minimum space width with an exposure time of 280 milliseconds, while 280 nm with the same exposure conditions. A resist film thickness of 0 μm can be obtained at the space width, that is, the maximum space width. Therefore, for example, by controlling the space width in increments of 10 nm, a target resist film thickness of 0 to 3.5 μm can be set with 16 gradations.

  The isolation groove 302 of the silicon bench 300 according to the embodiment of the present invention has a depth of 200 μm as described above. The applied resist film thickness is 3.5 μm. The resist shape is transferred to a silicon substrate to produce a three-dimensional shape. The level difference is adjusted by finely adjusting the selection ratio between the resist and silicon obtained from the silicon etching conditions, so that the level difference of 3.5 μm in resist thickness is enlarged and transferred to 200 μm.

  The photomask in this case is under the same conditions as the case of the second photomask according to the second invention described in the first embodiment, and in this case, the third light intensity <the first light intensity as the normalized light intensity. This is a case where the condition of 1 light intensity ≦ 1 is added.

  FIG. 6 shows the arrangement of mask cells with respect to the shape of each resist pattern, the shape of the resist pattern after exposure and development, and the shape of the pattern of each groove formed on the etched silicon surface after silicon etching. is there. FIG. 6A is a diagram for explaining the arrangement of the mask cells with respect to the shape of each resist pattern. FIG. 6B is a diagram showing the shape of the resist pattern after exposure and development by each mask cell group. FIG. 6C is a diagram showing a cross section of the silicon substrate after etching using the resist pattern having the shape of each resist pattern after being exposed and developed by each mask cell as a mask.

In FIG. 6A, FIG. 6B, and FIG. 6C, the region 404 of the mask cell group composed of mask cells having a minimum space width D _min of 120 nm has a resist residual rate of 100% after exposure and development, Thus, the resist layer is not developed and becomes a region 402 that remains on the silicon substrate 400 completely. Accordingly, the region 402 is a region other than the separation groove and the V groove.

Further, in the mask cell group region 406 composed of mask cells having a maximum space width D _max of 280 nm, the resist remaining rate after exposure and development is 0%, that is, the resist layer is locally removed by the development process, and an opening is formed in the resist layer. This is a region to be formed, which is a region of a separation groove 410 in which etching of the silicon substrate 400 is processed to a depth of 200 μm.

Further, the space width of the mask cells constituting the mask cell group region 408 in the V-groove region is a space width that changes stepwise between the minimum space width D _min of 120 nm and the maximum space width D _max of 280 nm. Take the value. As an example, two space width values D ₁ and D ₂ are shown. Increases linearly from the minimum space width D _min in one long side of the value V-groove region of the stepwise sequential space width, takes a maximum value D ₂ in the V-groove tip, and is the other long side It has a linearly decreasing change to the minimum space width _Dmin . Thus, the photomask region forming the V-groove region is a mask cell group region in which a continuous space width value (in increments of 10 nm) is set. Therefore, the developed shape of the resist layer is a resist region whose film thickness is changed into a V-groove shape. The resist pattern is etched while maintaining the shape of the resist pattern by etching, and the silicon substrate is finally etched into the V-groove pattern to form the V-groove 412.

  As a result, a silicon bench having a separation groove and a V-groove is produced.

  The processing steps from the resist coating step to etching are as follows. After applying the resist, pre-bake treatment is performed at an atmospheric temperature of 90 ° C. for 60 seconds, followed by exposure for 280 milliseconds using an i-line stepper, and then post-exposure bake treatment for 100 seconds at an atmospheric temperature of 110 ° C. I do. Next, after performing a development process for 90 seconds using an alkaline developer (for example, product name NMD-3, manufactured by Tokyo Ohka Kogyo Co., Ltd.), a post-development baking process for 100 seconds at an atmospheric temperature of 120 ° C. Thus, a resist pattern is obtained. Etching was performed using an inductively coupled plasma-reactive ion etching (ICP-RIE) apparatus that is generally used in the production of micromachines.

(Third Embodiment: Silicon Bench Manufacturing Method Using a Photomask, Part 2)
As a third embodiment, a fourth invention of the present invention will be described. That is, in the silicon bench manufacturing method, a mode in which separation grooves, component placement V-grooves, and component placement alignment marks having different depth shapes are simultaneously formed on the surface of the silicon substrate will be described.

  The alignment mark for component placement is based on a rectangular pattern, and has a shallower depth on the surface of the silicon bench compared to a separation groove or a component placement V-groove. Therefore, the mask pattern arrangement procedure of the photomask is executed by the same method as that described in the second embodiment.

  The used silicon substrate, resist pattern formation conditions, i-line stepper exposure conditions, mask cell pattern pitch, etc. are exactly the same as in the second embodiment. First, the space width of each mask cell corresponding to the separation groove, the V groove for component placement, and the alignment mark for component placement and the residual resist film thickness after development are determined from the characteristic curve of FIG. .

  According to the characteristic curve shown in FIG. 5, as described in the second embodiment, the resist film thickness of 3.5 μm is obtained when the space width is 120 nm, that is, the minimum space width is 280 milliseconds. On the other hand, a resist film thickness of 0 μm can be obtained when the space width is 280 nm, that is, the maximum space width under the same exposure conditions. Therefore, for example, by controlling the space width in increments of 10 nm, a target resist film thickness of 0 to 3.5 μm can be set with 16 gradations.

  FIG. 7 shows the arrangement of the mask cell with respect to the shape of each resist pattern, the shape of the resist pattern after exposure and development, and the shape of the pattern of each groove formed on the etched silicon surface after silicon etching. is there. FIG. 7A is a diagram for explaining the arrangement of the mask cells with respect to the shape of each resist pattern. FIG. 7B is a diagram showing the shape of the resist pattern after exposure and development by each mask cell group. FIG. 7C is a view showing a cross section of the silicon substrate after etching using the resist pattern having the shape of each resist pattern after being exposed and developed by each mask cell as a mask.

In FIG. 7A, FIG. 7B, and FIG. 7C, the region 504 of the mask cell group consisting of mask cells having a minimum space width _Dmin of 120 nm has a resist residual rate of 100% after exposure and development, Thus, the resist layer is not developed and becomes a region 502 that remains on the silicon substrate 500 completely. Accordingly, this region 502 is a region other than the separation groove, the component placement V-groove, and the component placement alignment mark. Therefore, this region is a region where the silicon substrate is not etched.

Further, in the mask cell group region 506 composed of mask cells having a maximum space width D _max of 280 nm, the resist remaining rate after exposure and development is 0%, that is, the resist layer is locally removed by the development process, and an opening is formed in the resist layer. This is a region to be formed, and serves as a region of a separation groove 512 in which etching of the silicon substrate 500 is processed to a depth of 200 μm.

Further, the space width of the mask cell constituting the mask cell group region 508 in the V-groove region for component placement changes stepwise between the minimum space width _Dmin of 120 nm and the maximum space width _Dmax of 280 nm. Take the value of the space width. As an example, two space width values D ₂ and D ₃ are shown. The stepwise sequential space width value increases linearly from the minimum space width D _{min on} one long side of the V-groove region for component placement, takes a maximum value D ₃ at the tip of the V-groove, and the other It has a change that linearly decreases to the minimum space width _Dmin that is the long side. As described above, the photomask region that forms the V-groove region for component placement is a region of a mask cell group in which a continuous space width value (space width increments of 10 nm) is set. Therefore, the developed shape of the resist layer is a resist region whose film thickness is changed into a V-groove shape. The resist pattern is etched while maintaining the shape of the resist pattern by etching, and finally the silicon substrate is etched into the V-groove pattern to form the V-groove 514.

Next, the value of the space width D ₁ of the mask cells constituting the mask cell group region 510 in the component placement alignment mark region takes a value in the range of D _min <D ₁ <D ₂ . That is, the resist pattern in this region after resist development has a vertical groove shape shallower than the V-groove resist pattern for component placement, and the resist is etched while maintaining the shape of the resist pattern by etching. After the substrate is etched, an alignment mark 516 for component placement is formed.

  As a result, a silicon bench in which a separation groove, a component placement V-groove, and a component placement alignment mark having different depth shapes are simultaneously formed on the surface of the silicon substrate can be manufactured.

  The alignment mark for component placement is mounted with high alignment accuracy in order to mount a desired component at a predetermined position such as a V-groove when mounting an optical element, an electronic component, an optical fiber, or the like on a silicon bench. Is for. Therefore, when the silicon bench is formed at the same time as the separation groove and the V-groove, the mounting accuracy is expected to be remarkably improved as compared with the prior art.

  In addition, in each embodiment mentioned above, the suitable form is illustrated and it is not limited to the content. Here, an i-line stepper is used for the exposure apparatus, but a g-line (wavelength 436 nm) stepper, a KrF (wavelength 248 nm) stepper, an ArF (wavelength 193 nm) stepper, or the like may be used.

  Further, although a mode in which a positive resist is used as a resist has been described, a negative resist may be used to increase the resist residual film thickness as the irradiated light intensity increases.

It is a schematic diagram for demonstrating the photomask of this invention. It is a schematic diagram for demonstrating the 1st invention of this invention. It is a schematic diagram for demonstrating 2nd invention of this invention. It is a figure for demonstrating the manufacturing method of the silicon bench by 3rd invention of this invention. It is a figure for demonstrating the resist film thickness after exposure with respect to the space width of this invention, and image development. Mask cell arrangement for each resist pattern shape for explaining the third invention of the present invention, resist pattern shape after exposure and development, and pattern of each groove formed on the etched silicon surface after silicon etching It is a figure for demonstrating the shape of. Mask cell arrangement for each resist pattern shape for explaining the fourth aspect of the present invention, resist pattern shape after exposure and development, and pattern of each groove formed on the etched silicon surface after silicon etching It is a figure for demonstrating the shape of.

Explanation of symbols

10, 100, 200: Photomasks 20, 102, 202: Mask substrate 30: Light shielding film 40: Mask cell 42: Light shielding region 44: Light transmission region 46: Virtual grid line 48: Virtual bisector 110, 210: First rectangle Regions 112 and 212: First mask cell group 120, 220: Second rectangular region 122, 222: Second mask cell group 130, 230: Regions 132 other than the first and second rectangular regions, 232: Third mask cell group 300: Silicon Bench 302, 410, 512: Separation groove 304, 412, 514: V groove 400, 500: Silicon substrate 402, 502: Resist 404, 504: Mask cell group region 406 consisting of mask cells having a minimum space width _Dmin of 120 nm , 506: Masukuse the maximum space width _{D max} consists of 280nm of the mask cell Group of regions 408, 508: region of mask cells groups in the area of the V-groove 510: region of mask cells groups in the alignment mark region 516: the alignment mark

Claims (4)

An exposure photomask for forming a resist pattern having a non-uniform film thickness,
A transparent mask substrate and a plurality of square mask cells arranged in close contact with the mask substrate;
The length of one side of the mask cell is set shorter than the length that is the resolution limit of the optical system of the exposure apparatus in which the photomask is used,
The mask cell has one or both of a light transmission region and a light shielding region formed of a light shielding film provided on the mask substrate,
The light intensity of the transmitted light of the mask cell is a normalized light intensity,
The light intensity of the transmitted light is determined by the area ratio of the light transmitting region to the mask cell,
A first rectangular region and a second rectangular region are partitioned in a planar region when the photomask is viewed from above;
The first mask cell group included in the first rectangular region has a first light intensity (where 0 <first light intensity <1),
A second mask cell group included in the second rectangular region has a second light intensity (where 1st light intensity <second light intensity ≦ 1); and
The remaining third mask cell group outside the first and second rectangular regions has a third light intensity (provided that 0 ≦ third light intensity <1). An exposure photomask for forming a resist pattern having a non-uniform film thickness,
A transparent mask substrate and a plurality of square mask cells arranged in close contact with the mask substrate;
The length of one side of the mask cell is set shorter than the length that is the resolution limit of the optical system of the exposure apparatus in which the photomask is used,
The mask cell has one or both of a light transmission region and a light shielding region formed of a light shielding film provided on the mask substrate,
The light intensity of the transmitted light of the mask cell is a normalized light intensity,
The light intensity of the transmitted light is determined by the area ratio of the light transmitting region to the mask cell,
A first rectangular region and a second rectangular region are partitioned in a planar region when the photomask is viewed from above;
The first mask cell group included in the first rectangular region has a first light intensity (where 0 <first light intensity <1),
The second mask cell group included in the second rectangular area has a second light intensity (where 0 ≦ second light intensity <first light intensity) on two sides in the longitudinal direction of the second rectangular area. And has a third light intensity greater than the second light intensity (where second light intensity <third light intensity <1) on the longitudinal center line, and the two sides And a center line having a light intensity that linearly changes from the second light intensity to the third light intensity, and
The remaining third mask cell group outside the first and second rectangular regions has the second light intensity. In manufacturing a silicon bench using the photomask for forming a resist pattern according to claim 1 or 2,
After forming the resist pattern having a plurality of shapes and thicknesses on a resist layer formed on the silicon substrate using the photomask by a development process, the resist pattern on the silicon substrate is used as a mask. A method for manufacturing a silicon bench, wherein the surface of the silicon substrate is etched in a batch with the same shape as in FIG. In the manufacturing method of the silicon bench of Claim 3,
A method for manufacturing a silicon bench, wherein a separation groove having a different depth shape, a V groove for component placement, and an alignment mark for component placement are simultaneously formed on the surface of the silicon substrate.

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