JP2012063390A - Exposure device and light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an exposure device and a light source device performing exposure by effectively emitting light of a required wavelength range and required amount with low power consumption, and with a long service life.SOLUTION: A light source unit 41 includes a first LED array 411, a first lens array 412, a second LED array 413, a second lens array 414, a dichroic mirror 415, a third lens array 416, and a first imaging optical system 417. The first LED array 411 emits light of center wavelength 385 nm. The second LED array 413 emits light of center wavelength 365 nm. The dichroic mirror 415 superimposes an image of a light emission section 413c of the second LED array 413 on an image of a light emitting section 411c of the first LED array 411.

Description

  The present invention relates to an exposure apparatus and a light source apparatus, and more particularly to an exposure apparatus used for manufacturing a printed circuit board for an electronic industry, a semiconductor or a liquid crystal display, and a light source apparatus used for the exposure apparatus.

  For example, a surface patterning technique using a photolithography method is generally used in processing steps such as a printed circuit board for an electronic industry, a semiconductor wafer, and a glass substrate for manufacturing a liquid crystal display. Conventionally, for example, in the manufacturing process of a printed circuit board, a film of a photosensitive material (photosensitive resin, etc.) is formed on the printed circuit board by a technique such as coating or laminating, and exposed through a photomask having a desired pattern. A pattern was formed on the film of the photosensitive material.

  In recent years, an exposure method called direct drawing, in which exposure is performed with light modulated using a light modulation element such as a DMD (digital micromirror device) without using a photomask, and a pattern is directly drawn, is also used. Became.

JP 2003-332221 A JP 2006-133635 A

  In the direct drawing type exposure apparatus disclosed in Patent Document 1, a lamp is used as a light source. However, an ultra-high pressure mercury lamp generally used in this type of apparatus is large in size, consumes a large amount of power, and has a long life. There was a problem of being short. Therefore, as shown in Patent Document 2, it has also been proposed to use a light-emitting diode (LED) with low power consumption and a long life as a light source.

  However, depending on the characteristics of the photosensitive material that is the subject of exposure, it may be required to irradiate light in a relatively wide wavelength range. If an LED having a narrow wavelength range of irradiating light is used, desired characteristics can be obtained. Therefore, patterning cannot be performed well. For example, since it is necessary to irradiate light of a relatively wide wavelength range near 360 to 390 nm for exposure of a solder resist, it is sufficient to irradiate light from a single wavelength LED having a peak at 365 nm. There are inconveniences such that the exposure cannot be performed and the pattern cross section of the solder resist has a reverse taper shape.

  On the other hand, it is conceivable to mix two types of LEDs that emit light of different wavelengths in the light source described in Patent Document 2, but this time for the exposure when the number of LEDs per wavelength decreases. A sufficient amount of light cannot be obtained.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a light source device and an exposure device that have low power consumption, have a long service life, and can efficiently emit light in a necessary wavelength region with a necessary amount of light. Yes.

  According to a first aspect of the present invention, there is provided a first light source array in which a plurality of light source elements each having a light emitting unit that emits light having a first wavelength characteristic is arranged, and a light emitting unit of each light source element of the first light source array. A first lens array in which a plurality of lenses forming a magnified image are arranged; a second light source array in which a plurality of light source elements each having a light emitting section that emits light having a second wavelength characteristic; and the second light source array. A second lens array in which a plurality of lenses forming an enlarged image of the light emitting part of each light source element are arranged, an image of the light emitting part of the first light source array formed by the first lens array, and the second An optical composition element that forms a composite image by superimposing the image of the light emitting part of the second light source array formed by the lens array, and a light beam of uniform illuminance distribution by combining the light flux of the composite image synthesized by the optical composition element And a uniformizing element that emits It is characterized in.

  According to a second aspect of the present invention, there is provided the light source device according to the first aspect, wherein the principal ray of the luminous flux of the composite image for each light emitting portion of each light source element formed by the optical synthesis element is parallel to the optical axis. And a both-side telecentric first imaging optical system that projects the combined image emitted from the third lens array on the incident end of the uniformizing element in a reduced manner. To do.

  According to a third aspect of the present invention, in the light source device according to the first or second aspect, the first lens array includes a light emitting portion of each light source element of the first light source array, and an arrangement pitch of the light source elements. The second lens array projects the light emitting portion of each light source element of the second light source array to the size of the arrangement pitch of the light source elements. It is characterized by that.

  According to a fourth aspect of the present invention, in the light source device according to any one of the first to third aspects, the image forming apparatus further includes a second imaging optical system that projects the light beam emitted from the uniformizing element onto a predetermined illumination area. It is characterized by that.

  According to a fifth aspect of the present invention, in the light source device according to any one of the first to fourth aspects, the uniformizing element is a hollow light pipe or a solid rod.

  According to a sixth aspect of the present invention, in the light source device according to any one of the first to fifth aspects, the optical combining element is a dichroic mirror.

  According to a seventh aspect of the present invention, a light source device according to any one of the first to sixth aspects, a light modulation element illuminated by the light source device, and light modulated by the light modulation element are used as a drawing object. An exposure apparatus comprising: an irradiation projection optical system; and a scanning mechanism that scans the drawing object by relatively moving the projection optical system and the drawing object.

  According to an eighth aspect of the present invention, there is provided a light source device according to the sixth aspect, a light modulation element illuminated by the light source device, and a drawing in which a light modulated by the light modulation element is formed with a solder resist film. A projection optical system that irradiates an object; and a scanning mechanism that scans the drawing object by relatively moving the projection optical system and the drawing object; and the light emitting element of the first light source array has a wavelength A light emitting unit that emits light having a peak near 385 nm, the light emitting element of the second light source array has a light emitting unit that emits light having a peak near 365 nm, and the dichroic mirror includes the first light emitting element. An exposure apparatus arranged to transmit light from one light source array and to reflect light from the second light source array to form a composite image.

  According to the first to sixth aspects of the present invention, it is possible to obtain a light source device that consumes less power, has a long lifetime, and can emit light in a necessary wavelength range for exposure.

  According to the second aspect of the present invention, a light beam having a desired shape can be emitted particularly efficiently.

  According to the seventh aspect of the present invention, there can be obtained an exposure apparatus which can be exposed by emitting light in a necessary wavelength region with low power consumption and long life.

  According to the eighth aspect of the present invention, there can be obtained an exposure apparatus capable of performing exposure by emitting light having a wavelength characteristic particularly suitable for exposure of a solder resist.

It is a schematic diagram which shows the exposure apparatus which concerns on embodiment of this invention. It is a figure which shows DMD. It is a typical perspective view which shows a part of illumination optical system. It is a side view of a light source unit. It is a side view which extracts and shows a part of light source unit. It is a figure which shows the external appearance of a LED chip, and its projection image. It is a perspective view which extracts and shows a part of light source unit. It is a figure which shows the spectral wavelength characteristic of emitted light.

    <1. Overview of exposure apparatus configuration and operation>

  FIG. 1 is a schematic diagram showing a configuration of an exposure apparatus 1 according to an embodiment of the present invention. In FIG. 1, in order to show the internal structure of the apparatus, the outline of the apparatus is shown by a broken line. The exposure apparatus 1 performs pattern formation by exposing a predetermined pattern onto a printed circuit board (hereinafter simply referred to as a substrate) 9 on which a solder resist film is formed by coating or laminating. The stage 2 to be held, the stage moving mechanism 31 that moves the stage 2 in the Y direction in FIG. 1, the head unit 4 that emits a light beam toward the substrate 9, and the head unit 4 are moved in the X direction in FIG. And a control unit 5 connected to the stage moving mechanism 31, the head unit 4, and the head unit moving mechanism 32.

  The head unit 4 incorporates an optical system including a light source unit 41 that emits a light beam of a predetermined wavelength as described later and a DMD 42 provided with a group of micromirrors arranged in a grid, and the micromirror group of the DMD 42 As a result, the light beam from the light source unit 41 is reflected to generate a spatially modulated light beam, which is emitted to the substrate 9 held on the stage 2 and exposed to form a pattern.

  An outline of the optical system will be described. The light beam emitted from the light source unit 41 is guided to the mirror 436 via the rod integrator 433, the lens 434a, the lens 434b, and the mirror 435, and the mirror 436 guides the light beam to the DMD 42 while condensing the light beam. The light beam incident on the DMD 42 is uniformly irradiated onto the micromirror group of the DMD 42 at a predetermined incident angle (for example, 24 degrees). As described above, the light source unit 41, the rod integrator 433, the lens 434a, the lens 434b, the mirror 435, and the mirror 436 constitute the illumination optical system 43a that guides the light from the light source unit 41 to the DMD 42.

  A light beam (that is, spatially modulated) formed only by the reflected light from the micromirrors in a predetermined posture (the posture corresponding to the ON state in the description of light irradiation by the DMD 42 described later) among the micromirrors of the DMD 42 Light beam) enters the zoom lens 437, the magnification is adjusted by the zoom lens 437, and the light beam is guided to the projection lens 439 through the mirror 438. Then, the light beam from the projection lens 439 is irradiated onto a region on the substrate 9 that is optically conjugate with the micromirror group. Thus, in the exposure apparatus 1, the zoom lens 437, the mirror 438, and the projection lens 439 constitute the projection optical system 43b that guides the light from each minute mirror to the corresponding light irradiation region on the substrate 9.

  The stage 2 is fixed to the moving body side of the stage moving mechanism 31 that is a linear motor, and the control unit 5 controls the stage moving mechanism 31 so that the light irradiation region group (1 The two micromirrors correspond to one light irradiation region.) Moves relatively on the photoresist film in the Y direction in FIG. That is, the light irradiation region group is fixed relative to the head unit 4, and the light irradiation region group moves on the substrate 9 by the movement of the substrate 9.

  The head unit 4 is fixed to the moving body side of the head unit moving mechanism 32 and intermittently moves in the sub-scanning direction (X direction) perpendicular to the main scanning direction (Y direction in FIG. 2) of the light irradiation region group. . That is, every time main scanning ends, the head unit moving mechanism 32 moves the head unit 4 in the X direction to the start position of the next main scanning. Then, by driving the stage moving mechanism 31 and the head moving mechanism 32, the head 4 scans and exposes the surface of the substrate 9.

  FIG. 2 is a diagram showing the DMD 42. The DMD 42 includes a group of micromirrors 422 in which a large number of micromirrors are arranged on a silicon substrate 421 at regular intervals in a lattice shape (described below as M2 rows and N columns in two directions perpendicular to each other). Each of the micromirrors is tilted by a predetermined angle by electrostatic field action according to data written in the memory cell corresponding to each micromirror.

  When a reset pulse is input from the control unit 5 shown in FIG. 1 to the DMD 42, the micromirrors are simultaneously tilted in a predetermined posture with the diagonal line of the reflecting surface as an axis according to the data written in the corresponding memory cell. As a result, the light beam applied to the DMD 42 is reflected according to the direction in which each micromirror is tilted, and light irradiation to the light irradiation region is turned on / off. That is, when a micromirror in which data indicating ON is written in the memory cell receives a reset pulse, the light incident on the micromirror is reflected to the zoom lens 437, and the corresponding light irradiation region is irradiated with light. When the micromirror is turned off, the micromirror reflects incident light to a predetermined position different from that of the zoom lens 437, and the corresponding light irradiation region is in a state where light is not guided.

  With this configuration, the surface of the substrate 9 is irradiated with the light beam modulated by the DMD 42 while being relatively scanned by the head unit 4 to form a predetermined pattern on the solder resist on the surface of the substrate 9.

    <2. Details of optical system>

  Next, details of the optical system will be described. 3 is a schematic perspective view showing a part of the illumination optical system 43a including the light source unit 41, FIG. 4 is a side view of the light source unit 41, and FIG. 5 is a side view showing a part of the light source unit 41. FIG. 6 is a view showing the appearance of the LED chip and a projected image thereof, and FIG. 7 is a perspective view showing the first LED array 411, the first lens array 412, and the third lens array 416.

  The light source unit 41 includes a first LED array 411, a first lens array 412, a second LED array 413, a second lens array 414, a dichroic mirror 415, a third lens array 416, and first imaging optics. A system 417.

  The first LED array 411 is configured by arranging twelve LED chips (LED dies) 411a each having a light emitting portion that emits light having a central wavelength of 385 nm (first wavelength characteristic) on a substrate 411b. The LED chip 411a has a size of 1 mm square and is housed in a ceramic package (not shown). The LED chip 411a does not emit light on its entire surface of 1 mm square, but has a non-light emitting portion due to the influence of the shadow of the electrode. In the LED chip 411a in this embodiment, as shown in FIG. 6A, a light emitting portion 411c shown by hatching in the range of 0.8 mm square of the surface is formed. In the first LED array 411, the ceramic packages of the respective LED chips 411a are arranged on the substrate 411b so that the LED chips 411a are arranged in 3 × 4 in a vertical and horizontal two dimensions at a pitch of 10 mm (d = 10 mm in FIG. 5). Attach to. Further, a cover glass 411d for protecting the surface is provided on the front surface of each LED chip 411a.

  The first lens array 412 is a 3 × 4 lens group that forms an image of the light emitting portion 411c of each LED chip 411a of the first LED array 411 in the same vertical and horizontal two dimensions corresponding to the arrangement of the LED chips 411a. A lens that is formed by arranging twelve, and is constituted by two pieces of a biconvex first lens 412a and a planoconvex second lens 412b as seen from the LED chip 411a side per LED chip 411a. It has a group and is assembled with the frame 412c. (In FIG. 7, the first lens 412a is shown through the substrate 411b.) The lens group of the first lens 412a and the second lens 412b is a 0.8 mm square in which the light emitting portion 411c exists in the LED chip 411a. Is enlarged and projected to the size of the arrangement pitch (indicated by d in FIG. 5) of the LED chips 411a, that is, the size of 10 mm square. The projected image of the light emitting unit 411c covers the entire surface of each individual lens 416a constituting a third lens array 416, which will be described later.

  The second LED array 413 is configured by arranging twelve LED chips 413a having a light emitting unit that emits light having a center wavelength of 365 nm (second wavelength characteristic) on a substrate 413b. The configurations of the second LED array 413 and the LED chip 413a are the same as those of the first LED array 411 and the LED chip 411a shown in FIG. 5 except for the wavelength of the emitted light of the LED chip 413a. The ceramic packages of the respective LED chips 413a are attached on the substrate 413b so as to be arranged in a pitch of 3 × 4 in two dimensions vertically and horizontally. A cover glass 413d for protecting the surface is provided on the front surface of each LED chip 413a.

  The configuration of the second lens array 414 is the same as that of the first lens array 412 described above, and a lens group that forms an image of the light emitting portion 413c of each LED chip 413a of the second LED array 413 is replaced with an LED chip. 12 × 3 × 4 are arranged in the same vertical and horizontal dimensions corresponding to the arrangement of 413a, and each LED chip 413a is flat with the biconvex first lens 414a when viewed from the LED chip 413a side. It has a lens group composed of two convex second lenses 414b, and is assembled by attaching them to a frame 414c. Similar to the first lens array 412 shown in FIG. 5, the lens group of the first lens 414a and the second lens 414b has an approximately square area of 0.8 mm square in which the light emitting portion 413c exists in the LED chip 413a. The LED chips 413a are enlarged and projected to the size of the arrangement pitch, that is, the size of 10 mm square. The projected image of the light emitting unit 413c covers the entire surface of each lens 416a that constitutes a third lens array 416 described later.

  A dichroic mirror 415 is arranged obliquely between the first lens array 412 and the image of the light emitting portion 411c of each LED chip 411a of the first LED array 411 formed by the first lens array 412, and further, the dichroic mirror 415 is The second lens array 414 and the second LED array 413 are arranged on the opposite side of the first lens array 412. (In FIG. 5, the dichroic mirror 415, the second lens array 414, etc. are not shown.) Thus, the dichroic mirror 415 transmits light from the first LED array 411 and the first lens array 412. In addition, the light from the second LED array 413 and the second lens array 414 is reflected, and the image of the light emitting part 413c of the second LED array 413 is reflected on the image of the light emitting part 411c of the first LED array 411. They are arranged so as to be combined. As a result, the synthesized image by the first lens array 412 and the second lens array 414 is arranged by enlarging the shapes of the light emitting portions of the LED arrays 411 and 413 as shown in FIG. 6B. It has become.

  The light of the first LED array 411 has a center wavelength of 385 nm, the light of the second LED array 413 has a center wavelength of 365 nm, and the difference between them is about 20 nm. The mirror 415 needs to have a spectral reflectance (spectral transmittance) characteristic having a relatively steep edge. When the incident angle to the dichroic mirror 415 is 45 degrees or more, separation of the optical characteristics of the PS polarization component occurs and a steep characteristic cannot be obtained. Therefore, in this embodiment, the incident angle of each light is set to be more than 40 degrees. It is small. Also, in order to improve the efficiency of combining the two wavelengths of light, the second LED array 413 having a shorter wavelength is on the reflection side of the dichroic mirror 415 and the first LED array 411 having a longer wavelength is on the transmission side. , Use each.

  The third lens array 416 is disposed at the position of the combined image of the image of the first LED array 411 and the image of the second LED array 413 combined by the dichroic mirror 415, and the principal ray of the incident light beam is the optical axis. In parallel to the first imaging optical system 417 described later. The third lens array 416 is a 3 × 4 array of 10 mm square plano-convex lenses 416 a, and each lens 416 a has a similar shape (that is, a square shape) to each of the light emitting portions 411 c and 413 c, Moreover, it is substantially the same size as the composite image.

  The first imaging optical system 417 is a bilateral telecentric optical system, which includes a first lens 417a, a second lens 417b, and a third lens 417c, and a first LED array 411 formed by the dichroic mirror 415 and the first LED array 411. The combined image of the two LED arrays 413 is reduced and projected onto the incident end of the integrator 433. In view of efficiency, the shape of the incident end of the integrator 433 and the images of the light emitting portions of the first LED array 411 and the second LED array 413 reduced by the first imaging optical system 417 are substantially the same. preferable.

  The light with a uniform illuminance distribution output from the output end of the integrator 433 is irradiated to a predetermined illumination region of the DMD 42 by the second imaging optical system including the lens 434a, the lens 434b, the mirror 435, and the mirror 436. The As shown in FIG. 8, the wavelength spectrum of the light irradiated on the DMD 42 is a combination of light having a central wavelength of 385 nm of the first LED array 411 and light having a central wavelength of 365 nm of the second LED array 413. Here, the input current to each LED array is variable under the control of the control unit 5, and the intensity ratio of the light of two wavelengths can be varied. Thereby, the characteristic of the light to be irradiated can be set finely according to the resist characteristic to be irradiated, and for example, a desired pattern cross-sectional shape can be obtained according to the characteristic of the solder resist.

    <3. Operation and effect of exposure equipment>

  When the substrate 9 on which the solder resist film is formed is carried into the stage 2 of the exposure apparatus 1, the control unit 5 controls the stage moving mechanism 31, the head unit 4, the head unit moving mechanism 32, and the like to perform exposure processing. . At this time, the light source unit 41 illuminates the DMD 42 by outputting light obtained by combining the light with the central wavelength 385 nm emitted from the first LED array 411 and the light with the central wavelength 365 nm emitted from the second LED array 413. The solder resist on the substrate 9 is exposed by the light. The light emitted from the light source unit 41 is controlled to a current applied to each of the LED arrays 411 and 413 to be a light having a wavelength and intensity suitable for the substrate 9 to be processed, and the exposure is performed satisfactorily. In the light source unit 41, a sufficient number of LED chips 411a and 413a that emit light having a necessary wavelength in the two LED arrays 411 and 413 can be provided, and light having a necessary wavelength and light amount can be obtained.

    <4. Modification>

  In the above embodiment, the light from the first LED array 411 and the light from the second LED array 413 are synthesized by the dichroic mirror 415, and then telecentric by the third lens array 416, so that the first imaging is performed. Although it is reduced by the optical system 417, the third lens array 416 can be omitted, for example, as long as a slight decrease in efficiency can be tolerated. Further, the first imaging optical system 417 may be omitted depending on the shape of the emitted light beam required for the light source unit 41. If both are omitted, the light combined by the dichroic mirror 415 is directly incident on the input end of the integrator 433.

  In this embodiment, the dichroic mirror 415 is used to synthesize the light from the first LED array 411 and the light from the second LED array 413. Instead, for example, a cube-type dichroic prism is used. May be used. Further, three or more wavelengths of light may be synthesized according to the wavelength range of the required light. In that case, a plurality of dichroic mirrors 415 may be used as an optical synthesis element, or a cross prism, a Philips type A dichroic prism such as a prism or a Kester prism may be used.

  Here, an integrator 433 is used as a uniformizing element. This may be a hollow light pipe in which mirrors are bonded with the reflecting surface inside, or a solid rod of a polygonal column using total reflection. The incident-side cross-sectional shape and the output-side cross-sectional shape may be a taper type having a substantially similar shape. Further, a fly-eye lens may be used in place of the integrator 433. In this case, the shape of each lens of the fly-eye lens is preferably substantially similar to the shape of the irradiated surface, and is set at a position where the principal ray inside the first imaging optical system 417 intersects the optical axis. Thus, a uniform illuminance distribution can be realized.

DESCRIPTION OF SYMBOLS 1 Exposure apparatus 2 Stage 4 Head part 5 Control part 9 Substrate 31 Stage moving mechanism 32 Head part moving mechanism 41 Light source unit 42 DMD
411 1st LED array 411a LED chip 411c Light emitting part 412 1st lens array 413 2nd LED array 413a LED chip 413c Light emitting part 414 2nd lens array 415 Dichroic mirror 416 3rd lens array 417 1st connection Image optics

Claims (8)

A first light source array in which a plurality of light source elements each having a light emitting unit that emits light having a first wavelength characteristic are arranged;
A first lens array in which a plurality of lenses forming an enlarged image of a light emitting portion of each light source element of the first light source array are arranged;
A second light source array in which a plurality of light source elements each having a light emitting unit that emits light having a second wavelength characteristic are arranged;
A second lens array in which a plurality of lenses forming an enlarged image of a light emitting portion of each light source element of the second light source array are arranged;
A composite image is formed by superimposing the image of the light emitting part of the first light source array formed by the first lens array and the image of the light emitting part of the second light source array formed by the second lens array. An optical synthesis element to be formed;
A uniformizing element that emits a luminous flux of a composite image synthesized by the optical synthesis element as a luminous flux of uniform illuminance distribution; and
A light source device comprising: The light source device according to claim 1,
A third lens array that makes the principal ray of the luminous flux of the combined image for each light emitting part of each light source element formed by the optical combining element parallel to the optical axis;
A first imaging optical system that is telecentric on both sides that projects the combined image emitted from the third lens array on the entrance end of the homogenizing element in a reduced manner;
A light source device further comprising: The light source device according to claim 1 or 2,
The first lens array is an enlarged projection of the light emitting portion of each light source element of the first light source array to the size of the arrangement pitch of the light source elements,
The light source apparatus, wherein the second lens array projects a light emitting portion of each light source element of the second light source array in an enlarged size to an arrangement pitch of the light source elements. The light source device according to claim 1,
A light source apparatus further comprising a second imaging optical system that projects a light beam emitted from the uniformizing element onto a predetermined illumination area. The light source device according to any one of claims 1 to 4,
The light source device, wherein the uniformizing element is an integrator optical system. The light source device according to claim 1,
The light source device, wherein the optical combining element is a dichroic mirror. A light source device according to any one of claims 1 to 6,
A light modulation element illuminated by the light source device;
A projection optical system for irradiating a drawing object with light modulated by the light modulation element;
A scanning mechanism that scans the drawing object by relatively moving the projection optical system and the drawing object;
An exposure apparatus comprising: The light source device according to claim 6;
A light modulation element illuminated by the light source device;
A projection optical system for irradiating the object to be drawn on which the solder resist film is formed with light modulated by the light modulation element;
A scanning mechanism that scans the drawing object by relatively moving the projection optical system and the drawing object;
The light emitting element of the first light source array has a light emitting unit that emits light having a peak in the vicinity of a wavelength of 385 nm,
The light emitting element of the second light source array has a light emitting unit that emits light having a peak near a wavelength of 365 nm,
The dichroic mirror is arranged so as to transmit light from the first light source array and reflect the light from the second light source array to form a composite image.

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