JP2008242238A - Exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure apparatus for drawing a smooth oblique line without losing the energy of incident light. <P>SOLUTION: The exposure apparatus positions optical axes of light beams output respectively from a plurality of two dimensionally arrayed light source systems 11 with respect to a surface of an integrator 14 by a light converging optical system and make projection light output from the integrator 14 incident on a DMD 3 where a plurality of mirrors M are two dimensionally arrayed, and condenses light reflected by the mirrors M by individual microlenses 91a of a microlens array 91 having the same array with the mirrors M to form an image on a substrate 6, wherein the individual microlenses 91a of the microlens array 91 are aspherical lenses which have shapes similar to those of the mirrors M and circularly condense light having sectional shape perpendicular to an optical axis of incidence similar to the mirrors M. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention exposes a printed circuit board, a semiconductor, a photosensitive dry film on a liquid crystal surface, a liquid resist or the like using a spatial light modulator (Digital Micromirror Device-hereinafter referred to as “DMD”) without using a pattern mask. The present invention relates to a maskless exposure apparatus that exposes (draws) an electric circuit or the like on an object (hereinafter referred to as “substrate”) with light such as ultraviolet light.

  In order to expose a pattern on a printed circuit board, a liquid crystal display TFT substrate, a color filter substrate, or a plasma display substrate, conventionally, a mask as a pattern original is manufactured, and the substrate is exposed by a mask exposure apparatus using the mask original. It was. However, when a mask is produced for each substrate, there is a problem that the time required for commercialization becomes long. In order to solve this problem, in recent years, an exposure apparatus (Direct Exposure Machine, hereinafter referred to as “DE”) that directly draws (exposes) a desired pattern on a substrate using DMD has begun to spread.

  FIG. 5 is a block diagram of a conventional exposure apparatus.

  The light output from the light source 1 is converted into parallel light 1 a by the collimator lens 2 and enters the DMD 3. The DMD 3 has m square mirrors M each having a reflecting surface of 16 μm arranged in the horizontal direction and n columns in the vertical direction. A gap g of 1 μm (see FIG. 2) is provided between the mirror M and the adjacent mirror M. Each mirror M has a pair of ends in the diagonal direction as a fulcrum, and the other end can rotate about 10 degrees.

The DMD control device 4 individually controls each mirror M of the DMD 3 on / off (rotation control). When the mirror M is on, the parallel light 1a is reflected by the incident mirror M, is condensed by the microlens 5 provided for each mirror M via the projection optical system, is incident on the substrate 6, and is off. In this case, the light is incident on a position away from the substrate 6. The microlens 5 is provided for each mirror M, and the parallel light 1a reflected by the mirror M is converged in each side direction to form a spot S having a size of 2.83 μm on each side on the substrate 6. The substrate 6 is placed on the table 7 and is movable on the base 9 in the Y direction. Then, the mirror M is turned on while moving the substrate 6 in the Y direction, and the spot S is irradiated onto the substrate 6 to expose the pattern on the substrate 6. In the DMD 3 that is commercially available, since the mirrors M are aligned in the orthogonal direction, the DMD 3 is usually arranged inclining in the Y direction (Patent Document 1).
JP-A-11-320968

  By the way, when the spot S is a square, when an oblique line is drawn, an end portion (outline) in the width direction of the line becomes jagged. Therefore, for example, as shown in FIG. 6, the microlens 5 has a circular shape, and the arrangement thereof matches the arrangement of DMD mirrors to hold the microlens (hereinafter referred to as “microlens array”). If a reflective film is provided in a portion other than the microlens, the cross section (outer shape) of the light transmitted through the microlens can be made circular.

  However, in this case, as shown with hatching in the figure, a part of incident light (about 20%) is reflected, so that the energy utilization efficiency is lowered and the drawing speed is also lowered.

  An object of the present invention is to provide an exposure apparatus that can draw a smooth oblique line without damaging the energy of incident light.

  In order to solve the above problems, the present invention positions the optical axis of a light beam output from each of a plurality of two-dimensionally arranged light sources on the optical axis of the entrance surface of the integrator by a condensing optical system, and The outputted outgoing light is incident on a spatial light modulator in which a plurality of mirrors are arranged in two dimensions, and the light reflected by the mirror of the spatial light modulator is arranged in the mirror of the spatial light modulator. In the exposure apparatus for focusing on the individual microlenses of the microlens array that is the same as the arrangement of the above and forming an image on the workpiece, the individual microlenses of the microlens array are similar in shape to the mirror, A cross section perpendicular to the incident optical axis is an aspherical lens that condenses light having a shape similar to that of the mirror in a circular shape.

  In this case, it is more effective to arrange a light-shielding film on a portion other than the microlens on the surface on the light incident side of the microlens array.

  Further, when a light-shielding film is disposed on the light incident side of the microlens condensing position, and a plate-like pinhole array having pinholes having the same arrangement as the microlens arrangement is further provided It is effective. The pinhole array shapes the light emitted from the microlens so that the cross section perpendicular to the optical axis is circular.

  According to the present invention, smooth diagonal lines can be drawn without reducing energy utilization efficiency and drawing speed.

  1 is a block diagram of an exposure apparatus according to the present invention, FIG. 2 is a plan view of a microlens array, FIG. 3 is a plan view of a pinhole array, and FIG. 4 is a block diagram of an optical system in the direction of the central axis O. Those having the same function or the same function are denoted by the same reference numerals.

  A first condenser lens 12, a glass disc 13, an integrator 14, a second condenser lens 15, a mirror 16 and DMD3 are arranged on the optical axis O of the central light of the light source system 11 composed of a plurality of LDs. ing. On the reflection side of the mirror M (not shown) of the DMD 3, an image forming optical system 100 composed of an enlarged projection system 80 composed of lenses 81 and 82, a microlens array 91, a pinhole array 92, and lenses 101 and 102. Is arranged. Then, the projection imaging lens 30 is configured by the enlargement projection system 80, the microlens array 91, the pinhole array 92, and the imaging optical system 100.

  The table 7 can be moved in two orthogonal directions on the base 21 by a linear guide device 20. A linear scale (not shown) is attached to the table 7. The substrate 6 is vacuum-sucked by a suction hole (not shown) provided on the table 7 and fixed on the table 7.

  Next, each component will be described.

  In the light source system 11, blue (purple) laser diodes (hereinafter referred to as “LD”) are two-dimensionally arranged. The arrangement region of the LD is almost similar to the arrangement region of the mirror M of the DMD 3. Each LD emits light having a wavelength of 405 nm with an output of about 60 mW. The front focal point of the first condenser lens 12 is the virtual image position of the LD, and the rear focal point is the incident end of the integrator 14. The glass disk 13 is made of transparent glass, and unevenness of several μm is formed on the surface in the circumferential direction with a period of mm units. The glass disk 13 is disposed so as to intersect with the optical axis O that is the central axis of the light source system 11, and rotates around an axis parallel to the optical axis O. The motor 31 rotates the glass disk 13.

The integrator 14 is formed by laminating a plurality of rod lenses having a square cross section and a length L in two directions perpendicular to the optical axis O, and the end surfaces on the entrance side and the exit side of each rod lens each have a radius of curvature R. It is a spherical convex surface. When the refractive index of the glass constituting the rod lens is n, the length L of the rod lens 131 is L = nR / (n−1)
It is stipulated in.

  The rear end surface (surface from which light is emitted) of the integrator 14 whose front end surface (surface on which light is incident) is positioned on the rear focal plane of the first condenser lens 12 is positioned at the front focal point of the condenser lens 15. ing.

  Further, the rear end surface (exit position) of the integrator 14 is in an imaging relationship with the entrance pupil of the projection imaging lens 30 via the condenser lens 15. That is, the rear end surface of the integrator 14 is the front focal point of the condenser lens 14, and the rear focal point of the condenser lens 14 is positioned at the front focal point of the projection imaging lens 30.

  The DMD 3 has a two-dimensional array of 1024 × 768 mirrors M. The mirror M is a square with a side of 13 μm. A gap of 1 μm is provided between adjacent mirrors M.

  As shown in FIG. 2, 1024 × 768 microlenses having the same arrangement as the mirror M are arranged in the microlens array 91. The individual microlenses 91 a have a shape similar to that of the mirror M, that is, a shape enlarged by the magnification of the magnifying projection system 80. That is, in the case of a 3 × enlargement projection system, it is an angular shape with a size of 39 μm. Therefore, all the reflected light from the mirror M of the DMD 3 passes through the micro lens 91a. The microlens 91a is an aspheric lens, and condenses incident light having a square incident cross section into a circular cross section. A reflective film is formed on the incident surface of the microlens array 91 other than the microlens 91a.

  As shown in FIG. 3, pinholes P are formed in the plate-like pinhole array 92. The arrangement pitch of the pinholes P is the same as the arrangement pitch of the microlenses 91a, and the diameter is the same as the diameter of the image of the mirror M by the microlenses 91a. The pinhole array 92 is arranged so that the center of each pinhole P is coaxial with the center of each microlens 91a in a horizontal direction perpendicular to the optical axis O, and the mirror M is connected by the microlens 91a in the optical axis O direction. It is arranged according to the image position. A reflection film is formed on the incident surface other than the pinhole P of the pinhole array 92.

  Next, the operation of the present invention will be described.

  The light output from the LD of the light source system 11 is incident on the first condenser lens 12 with the respective optical axes being parallel to the optical axis O and spreading at a divergence angle of about 1 degree to form a substantially parallel beam. The light is emitted from the condenser lens 12. Then, the light passes through the glass disk 13 in a substantially parallel beam state and is incident on the position coincident with the center of the front surface of the integrator 14 with substantially parallel light. When the glass disk 13 is rotating, the phase of each parallel beam within the exposure time can be changed by 2π or more. For this reason, even in the case of output light from an LD with high coherence (spectrum width is narrow), the position of interference fringes generated between the light beams changes at high speed, averaged within the exposure time, and its presence is almost noticeable. Disappear. The inclination of the optical path of each parallel beam when the glass disk 13 is rotating is negligible in practice.

  The beam incident on the rod lens of the integrator 14 is narrowed down to the exit end surface by the effect of the spherical convex lens on the incident surface. That is, all the LDs constituting the light source system 11 are narrowed down (imaged) in accordance with the arrangement of the LDs on the end surface on the exit side of the rod lens. Due to the effect of the spherical convex lens on the exit surface, the beam exiting from the exit end surface of the rod lens does not depend on the incident angle of the incident light, and all of the emitted light has a principal ray parallel to the optical axis (parallel to the axis of the rod lens). It becomes.

  Then, the outgoing light emitted from the integrator 14 enters the second condenser lens 15, becomes a substantially parallel beam, exits from the condenser lens 15, and enters the DMD 3 in a substantially parallel beam state. That is, any light emitted from each rod lens constituting the integrator 14 illuminates the entire display area of the DMD 3.

  The light reflected by each mirror M of the DMD 3 is magnified by the magnifying optical system 80 (three times here), and forms an image on the micro lens 91a corresponding to each position. Then, the light condensed by the micro lens 91a forms an image in a circle at the position where the pinhole P on the optical axis O is disposed. The light that has passed through the pinhole array 92 passes through the projection lens 100 and forms an image on the substrate 6. When the exposure of the exposure area 51 is completed, the table 20 is moved in a direction perpendicular to the exposure direction, and the next exposure area 51 is positioned with respect to the projection lens 3.

  In this embodiment, since the light reflected by the mirror M is shaped into a circular light, for example, when a 45-degree line is drawn, a smooth straight line can be drawn.

  Further, since the pinhole array is arranged at the image forming position of the mirror M by the microlens, the light cross section can be surely made circular.

  Note that the pinhole array may not be provided.

It is a block diagram of the exposure apparatus which concerns on this invention. It is a top view of the micro lens array which concerns on this invention. It is a top view of a pinhole array. It is an optical system block diagram of the central axis O direction in FIG. It is explanatory drawing of a prior art. It is explanatory drawing of a prior art.

Explanation of symbols

3 DMD
6 Substrate 11 Light source system 14 Integrator 91 Micro lens array 91a Micro lens

Claims (4)

The optical axis of the light beam output from each of the plurality of light sources arranged two-dimensionally is positioned on the optical axis of the entrance surface of the integrator by the condensing optical system, and the plurality of mirrors outputs the output light output from the integrator. Each of the microlens arrays is incident on a spatial light modulator arranged in a dimension, and the light reflected by the mirror of the spatial light modulator is arranged in the same manner as the array of the mirrors of the spatial light modulator. In an exposure apparatus that focuses light by a microlens and forms an image on a workpiece,
The microlens is formed in a similar shape to the mirror, and a cross section in a direction perpendicular to the optical axis of an incident light beam is formed of an aspherical lens that condenses light similar to the mirror in a circular shape. Exposure device.   The exposure apparatus according to claim 1, wherein a light-shielding film is provided on a portion of the surface of the microlens array on the light incident side other than the microlens.   The pinhole array which shapes the cross section of the direction orthogonal to the said optical axis of the emitted light from each said micro lens into the circular shape in the condensing position of the said micro lens is provided. Exposure device.   4. The exposure according to claim 3, wherein the pinhole array includes a pinhole group in which a light-shielding film is disposed on a surface on which light is incident, and the arrangement is the same as the arrangement of the microlenses. apparatus.

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