JP4541010B2 - Pattern exposure apparatus and two-dimensional optical image generation apparatus - Google Patents

Description

  The present invention relates to a pattern exposure apparatus (also referred to as a maskless exposure apparatus) that directly draws a circuit pattern on a wafer without using a mask in an exposure process when manufacturing a semiconductor integrated circuit.

  In general, in an exposure process when manufacturing a semiconductor integrated circuit, a circuit pattern is exposed on a wafer coated with a resist using a mask (also called a reticle) on which a circuit pattern is drawn (also called pattern drawing). The apparatus used for this purpose is called an exposure apparatus or an exposure machine.

  On the other hand, in an apparatus called a mask drawing apparatus that performs pattern exposure used in a mask manufacturing process, an electron beam drawing apparatus using an electron beam is widely used, but a pattern exposure method using laser light in the ultraviolet region is used. A mask drawing apparatus based on the above has also been commercialized. As an example of the apparatus, a mirror device (referred to as a spatial light modulator or SLM) in which a number of micromirrors (micromirrors) each having a 16-micron-side square are arranged in a two-dimensional array is used. Is irradiated with pulsed ultraviolet laser light, and the mask substrate is exposed by the reflected light from the mirror device controlled by each micromirror, and the mirror surface of the mirror device is simply reduced on the substrate. It is configured to project. This is described in, for example, Proceedings of SPIE, Vol. 4186, pages 16 to 21 (Non-patent Document 1) or USP 6,428,940 (Patent Document 1).

  On the other hand, unlike the mask drawing apparatus, a pattern exposure apparatus that does not simply reduce the pattern of the mirror device may be used for pattern exposure on a printed circuit board or the like. An example of the configuration will be described using the conventional pattern exposure apparatus 200 shown in FIG. The ultraviolet light L21 that is the exposure light is reflected by the mirror 202, the ultraviolet light L22 is irradiated on the mirror device 201, the ultraviolet light L23 used for pattern exposure is reflected by the mirror device 201 and travels downward, and the lenses 203a and 203b Is projected onto the microlens array 205 by the projection optical system 204 configured as described above. The microlens array 205 divides the ultraviolet light L24 into a large number of thin light beams, which are condensed on each pinhole in the pinhole plate 206, respectively. An image of light on the exit surface of each pinhole of the pinhole plate 206 is pattern-projected as an aggregate of a large number of discrete spots on the substrate 209 by the reduction projection optical system 208. When the pinhole plate 206 in the pattern exposure apparatus 200 is viewed from above, as shown in FIG. 5, the arrangement of the pinholes is attached obliquely so as to be slightly inclined from the X and Y directions. As a result, as shown in FIG. 6, in order to scan the substrate 209 during drawing, the mirror device is turned on once (that is, the incident ultraviolet light is reflected so as to advance toward the substrate). The adjacent spots in the aggregate of a large number of discrete spots that form the projection area 210 of the pinhole plate 206 exposed in step 1 are gradually exposed by scanning the substrate 209.

  The drawing method using the pattern exposure apparatus as described above is called Point Array Scanning. For example, USP 6,473,237 (Patent Document 2), Japanese Patent Application No. 1077776 (Patent Document 3). Japanese Patent Application No. 2003 163851 (Patent Document 4), Japanese Patent Application 2003 No. 174017 (Patent Document 5), Japanese Patent Application No. 2003 374846 (Patent Document 6), Japanese Patent Application No. 2003 414863 (Patent Document) 7) etc. In addition, as a size of a product that is commercially available in the mirror device, for example, the size of one micromirror is about 13.7 microns on a side, and the number of pixels is, for example, 1024 × 768. The mirror surface of the device has a long side direction of about 14 mm and a short side direction of about 10.5 mm (hereinafter referred to as 14 × 10.5 mm).

Proceedings of SPIE, Vol.4186, pp. 16-21 USP 6,428,940 USP 6,473,237 Japanese Patent Application No. 1077776 Japanese Patent Application No. 1663851 Japanese Patent Application No. 174017 Japanese Patent Application No. 374846 Japanese Patent Application No. 2003-147663

  As a problem in configuring the pattern exposure apparatus by the point array scanning described above, it is difficult to use ultraviolet light having a wavelength of 0.4 μm or less at the wavelength of the light source. This is because the microlens array is usually made of resin, but the light source wavelength that can be used for the resin is about 0.4 microns or more, and is deteriorated by irradiation with ultraviolet light having a shorter wavelength. On the other hand, it is also difficult to manufacture a microlens array using an ultraviolet optical material such as quartz, which has a high transmittance with ultraviolet light.

  An object of the present invention is to provide a pattern exposure apparatus capable of pattern exposure by point array scanning without using a microlens array.

  In order to achieve the above object, in the pattern exposure apparatus of the present invention, a large number of ultraviolet ray generators are used as a light source, and a transfer optical system is used so that a large number of micromirrors of a mirror device can The ultraviolet light from the ultraviolet light generation part is projected by the transfer optical system and subjected to pattern exposure by the ultraviolet light reflected by the micromirror.

  Further, as an example for realizing the large number of ultraviolet ray generators, a laser may be configured using a reflecting mirror having a large number of pinholes as an output mirror. According to this, since the total area of the hole of the pinhole can be made as small as possible with respect to the beam cross-sectional area of the laser beam in the output mirror, the laser oscillation is not stopped by the pinhole. For example, in the case of an ion laser whose laser gain is small, the gain of one pass of the laser is as small as 10% or less, but it is easy to make the aperture ratio of the pinhole hole smaller than the gain, Laser oscillation can be performed, and as a result, ultraviolet rays are extracted from a large number of pinholes.

  In the pattern exposure apparatus of the present invention, since pattern exposure by point array scanning can be realized without using a microlens array, ultraviolet light having a wavelength of 0.4 microns or less can be used as a light source. Therefore, the resolution of the drawing pattern is increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of a pattern exposure apparatus 100 of the present invention. In the pattern exposure apparatus 100, the shower beam type laser 1 is used as a generation part of many ultraviolet rays. Here, it is modified based on an ion laser having a wavelength of 351 nm. On both sides of the laser tube 2, a laser resonator is assembled by a total reflection mirror 3 and an output mirror 4 with a pinhole. However, since the laser beam L1 (indicated by a thin dotted line) generated inside is as thin as about 1 mm, the beam diameter is expanded by a factor of 20 by the beam expander 5 and output with a pinhole. It hits mirror 4. In the output mirror 4 with a pinhole, 1024 × 768 = 786,432 holes having a diameter of 0.3 μm are formed vertically and horizontally at a pitch of about 13.7 μm in an area of 14 mm × 10.5 mm. Therefore, since the total area of the pinhole hole is 0.0556 square mm and the beam cross-sectional area of the diameter of 20 mm is 314 square mm, the loss due to the pinhole diameter is extremely small at 0.018%, which is sufficient for the laser. In addition to oscillation, a large number of ultraviolet rays L2 having high light intensity are generated like showers. The ultraviolet light L2 is polarized in a direction parallel to the paper surface.

  The shower beam-shaped ultraviolet ray L2 indicated by the thick dotted line passes through the transfer optical system 8a composed of the lens 7a and the lens 7b and the polarization beam splitter 6, passes through the λ / 4 wavelength plate 10, and It hits the mirror device 11. The ultraviolet light L2 passes through the λ / 4 wavelength plate 10 and changes to circularly polarized light. The lens 7a and the lens 7b have substantially the same focal length, and the transfer optical system 8a has a function of projecting one-to-one. That is, as an action of the transfer optical system 8 a, an image (that is, a large number of discrete spots) on the output mirror 4 with a pinhole is projected near the surface of the mirror device 11. Thereby, each thin beam of the ultraviolet light L2 emitted from the output mirror 4 with a pinhole comes into contact with each micromirror of the mirror device 11 on a one-to-one basis.

The ultraviolet light L2 that has become circularly polarized light is incident on the mirror device 11 having 1024 × 768 = 786,432 micromirrors. Ultraviolet rays pattern drawn with the substrate 12 is reflected to the opposite for each Ma Ikuromira mirror device 11. Therefore, it passes through the λ / 4 wavelength plate 10 again, and the polarization direction is returned to the linearly polarized light. However, since it is now a direction perpendicular to the paper surface, it is highly reflected by the polarization beam splitter 6 and proceeds downward. As a result, the light passes through the transfer optical system 8b composed of the lens 7c and the lens 7d and strikes the substrate 12 on the XY stage 13.

  On the other hand, the direction of reflection by the micromirrors in the mirror device 11 changes for ultraviolet rays that are not patterned on the substrate 12. That is, since it returns at an angle deviated from the opposite direction, after passing through the lens 7c, it cannot pass through the hole at the center of the pinhole plate 9, but is cut here.

  The function of the transfer optical system 8b is to project an image near the surface of the mirror device 11 onto the substrate 12. Further, as described above, since a large number of discrete spot images are projected as an image near the surface of the mirror device 11 by the transfer optical system 8a, a large number of discrete spots are projected (transferred) onto the substrate 12. Will come to be.

  As described above, in the present invention, the ultraviolet light L2 composed of a large number of thin ultraviolet rays as a light source is used, and an image of the output mirror 4 with pinholes forming the ultraviolet light L2 is consequently obtained on the substrate 12. A large number of discrete spots can be projected onto the substrate 12, and pattern exposure by point array scanning can be performed by scanning the substrate 12.

  Next, an apparatus having the same configuration as that of the pattern exposure apparatus 100 of the present invention described above, but using one transfer optical system will be described with reference to FIG. FIG. 2 is a block diagram of a pattern exposure apparatus 150 as a second embodiment of the present invention. The description of components common to the pattern exposure apparatus 100 shown in FIG.

  In the pattern exposure apparatus 150, the transfer optical system 8b omits the transfer optical system 8b in the pattern exposure apparatus 100, and the transfer optical system 8a performs an action equivalent to that of the transfer optical system 8b (that is, an action of projecting an image in the vicinity of the mirror device 11 onto the substrate 12). It is used together. For this reason, a pinhole plate 9 for cutting a light beam that is not exposed is disposed between the lens 7a and the lens 7b constituting the transfer optical system 8a.

  In the pattern exposure apparatus 150, the ultraviolet light that is drawn by the substrate 12 is reflected by the mirror device 11 and then passes through the λ / 4 wavelength plate 10 again to return the polarization direction to linearly polarized light. After passing, it is highly reflected by the polarization beam splitter 6 and travels toward the substrate 12 on the XY stage 13. In addition, the reflection direction of each ultraviolet ray in the mirror device 11 changes in the ultraviolet rays that are not patterned on the substrate 12. That is, since it is returned at an angle deviated from the opposite direction, it is cut by the pinhole plate 9 after passing through the lens 7b.

  The transfer optical system 8a of the present embodiment has an action of projecting an image of the output mirror 4 with a pinhole near the surface of the mirror device 11 and an action of projecting an image near the surface of the mirror device 11 onto the substrate 12. It has two actions. Further, the position of the substrate 12 is set to be equal to the polarization beam splitter 6 and the distance from the output mirror 4 with a pinhole. As described above, a large number of discrete spots projected near the surface of the mirror device 11 are projected on the substrate 12.

  Next, an example of the structure of the pinhole output mirror 4 used in the pattern exposure apparatuses 100 and 150 will be described with reference to FIG. In the output mirror 4 with a pinhole, a reflective film 32 is attached to one surface of the quartz substrate 31. This surface faces the inside of the shower beam type laser 1. On the other hand, an antireflection film 33 is attached to the opposite surface. The reflective film 32 is preferably an aluminum film with a protective film or a dielectric multilayer film. A large number of pinholes are open in the reflective film 32. In forming the pinhole, an accurate hole can be formed by forming the pinhole by exposure, development, and etching using an electron beam drawing apparatus or the like.

  An excimer laser may be used as the shower beam type laser 1 used in the first and second embodiments. An excimer laser is suitable for the present invention because it directly operates at a high output in the ultraviolet region. However, since the number of repetitions is up to about several kHz, when a light source with a higher number of repetitions is required, for example, the second harmonic of a copper vapor laser having a wavelength of 255 nm may be used. The copper vapor laser is not only easy to repeat at about 10 kHz, but in the case of the second harmonic, it can perform internal wavelength conversion. Therefore, the output mirror 3 with a pinhole as shown in FIG. Can be used.

  In the first and second embodiments, the shower beam type laser 1 is used as the light source. However, the present invention is not limited to the laser. For example, a large number of two-dimensional self-luminous devices such as a plasma display may be used.

  In addition, as the transfer optical system constituting the present invention, the first embodiment and the second embodiment have been configured with two lenses, but are not particularly limited to this configuration. Further, a lens system in which aberration is reduced by using a large number of lenses may be used, or a single lens with less aberration may be used. Furthermore, not only a lens but also an optical system including a concave mirror may be used. According to this, since chromatic aberration can be greatly reduced, a narrow-band light source is not necessary, and a wide-band excimer laser or ultraviolet lamp can be used.

1 is a diagram showing a configuration of a pattern exposure apparatus 100 according to a first embodiment of the present invention. It is a figure which shows the structure of the pattern exposure apparatus 150 which concerns on the 2nd Example of this invention. It is sectional drawing which shows a specific structure of the output mirror 4 with a pinhole used in FIG. It is a figure which shows the structure of the pattern exposure apparatus 200 proposed previously. It is a top view which shows the structure of the pinhole board 206 used for the pattern exposure apparatus of FIG. It is a figure explaining drawing by the pattern exposure apparatus 200 shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shower beam type laser 2 Laser tube 3 Total reflection mirror 4 Output mirror with pinhole 5 Beam expander 6 Polarizing beam splitter 7a, 7b, 7c, 7d, 203a, 203b Lens 8a, 8b Transfer optical system 9 Pinhole plate 10 λ / 4 wavelength plate 11, 201 Mirror device 12, 209 Substrate 13 XY stage 31 Quartz substrate 32 Reflective plate 33 Antireflection film 100, 200 Pattern exposure device 202 Mirror 204 Projection optical system 205 Micro lens array 206 Pinhole plate 210 Pinhole plate 206 projected area 211 Exposed area L1 Laser light L2 Ultraviolet rays L21, L22, L23, L24 Ultraviolet light

Claims (6)

In a pattern exposure apparatus that forms a pattern with a two-dimensional array of micromirrors,
Using a large number of ultraviolet ray generators as a light source,
A transfer optical system having a polarization beam splitter, two lenses, and a pinhole plate disposed between the two lenses on an optical path from the plurality of ultraviolet ray generators to the two-dimensional array of micromirrors , Λ / 4 wavelength plate in this order,
The multiple ultraviolet ray generators emit ultraviolet rays polarized in a predetermined direction,
The polarizing beam splitter is arranged in a direction to pass ultraviolet light polarized in the predetermined direction;
Using the transfer optical system, project the ultraviolet rays from the multiple ultraviolet ray generators onto the two-dimensional array of micromirrors,
A pattern exposure apparatus, wherein the substrate is subjected to pattern exposure with ultraviolet light reflected by the two-dimensional array of micromirrors and passed through the two lenses of the transfer optical system and the pinhole plate. 2. The pattern exposure apparatus according to claim 1 , wherein the generation unit of the plurality of ultraviolet rays includes a laser using a reflection mirror having a number of pinholes as an output mirror. 3. The pattern exposure apparatus according to claim 1, wherein the substrate is subjected to pattern exposure on an optical path between the plurality of ultraviolet ray generators and the substrate without using a microlens array. 4. In a two-dimensional optical image generator that forms a pattern with two-dimensional array of micromirrors,
Using a large number of ultraviolet ray generators as a light source,
A transfer optical system having a polarization beam splitter, two lenses, and a pinhole plate disposed between the two lenses on an optical path from the plurality of ultraviolet ray generators to the two-dimensional array of micromirrors , Λ / 4 wavelength plate in this order,
The multiple ultraviolet ray generators emit ultraviolet rays polarized in a predetermined direction,
The polarizing beam splitter is arranged in a direction to pass ultraviolet light polarized in the predetermined direction;
Using the transfer optical system, project the ultraviolet rays from the multiple ultraviolet ray generators onto the two-dimensional array of micromirrors,
Two-dimensional light image generation characterized in that a two-dimensional light image is output by ultraviolet rays reflected by the two-dimensional array of micromirrors and passed through the two lenses and the pinhole plate of the transfer optical system apparatus. 5. The two-dimensional light image generating apparatus according to claim 4 , wherein the generation unit of the plurality of ultraviolet rays includes a laser using a reflection mirror having a number of pinholes as an output mirror. 6. The two-dimensional optical image generation device according to claim 4, wherein a microlens array is not provided on an optical path from the plurality of ultraviolet ray generation units to the output of the two-dimensional optical image. .

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