JP2009244711A - Exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure device capable of maintaining exposure precision even when an ambient temperature is changed. <P>SOLUTION: In the exposure device wherein a projection imaging lens 30 is held on holders 50 and a plurality of holders 50 holding the projection imaging lens are arranged in a direction perpendicular to the moving direction of a substrate 6, a support includes a first support 60A having a very low coefficient of linear expansion and a second support 60B having a coefficient of linear expansion of β, and the holders 50 are held by the first support 60A and are arranged in the direction perpendicular to the moving direction of the substrate 6, and the first support 60A is supported by the second support 60B disposed in the moving direction of the substrate 6, and the second support 60B is fixed to a device body, and expression cα≈nβ is satisfied in α, β, c, n wherein: α is a coefficient of linear expansion of the holders 50; c is a distance from the first support 60A to a pupil A0 of the projection imaging lens 30; and n is a length from the device body fixing position of the second support 60B to the support position of the first support 60A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention provides a spatial light modulator (Digital Micromirror) without using a pattern mask.
Device—hereinafter referred to as “DMD”. ) To expose (draw) an electrical circuit or the like with light such as ultraviolet light on an object to be exposed (hereinafter referred to as “substrate”) such as a printed circuit board, a semiconductor, a photosensitive dry film on a liquid crystal surface, or a liquid resist. The present invention relates to a less exposure apparatus.

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. 3 is a block diagram of a conventional exposure apparatus.

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 includes m square mirrors M each having a reflecting surface of 13 μm arranged in the horizontal direction and n rows (for example, 1024 × 768) in the vertical direction. A gap of 1 μm is provided between adjacent mirrors 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. Each mirror M of the DMD 3 is individually turned on / off (rotation controlled). When the mirror M is on, the light incident on the mirror M is reflected toward the enlargement projection system 80, and when it is off, the light enters the position away from the enlargement projection system 80. In the DMD 3 that is commercially available, the mirrors M are arranged in an orthogonal direction, and therefore, the DMD 3 is usually arranged to be inclined in the Y direction.

  Next, the operation of the conventional exposure apparatus 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 the emitted light has a principal ray parallel to the optical axis (parallel to the rod lens axis). 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 (Patent Document 1). Further, hereinafter, the light source system 11 to the projection imaging lens 30 corresponding to the light source system 11 are collectively referred to as an “irradiation system”.

By the way, when there is one set of irradiation system, the exposure width, that is, the exposure width is about 60 to 70 mm. Therefore, a plurality of irradiation systems are provided in one exposure apparatus to improve work efficiency.

FIG. 4 is a side view of the holder, and FIG. 5 is a plan view of the vicinity of the projection imaging lens 30 when four sets of irradiation systems are provided.

The projection imaging lens 30 is accommodated in a cylindrical holder 50. The material of the holder 50 is aluminum. The holder 50 is fixed to the inner surface side of the support 60 by a bolt (not shown) through a seat portion 50a provided on the side surface. A0 in the figure is the position of the pupil of the projection imaging lens 30 and is on the optical axis (center axis) of the projection imaging lens 30. The light incident perpendicularly to the point B passes through the pupil A0 and enters perpendicularly from the point C.

Since the outer shape of the holder 50 is larger than the width of the exposure region in the X direction (the outer diameter is about 1.5 times the exposure width), the two adjacent holders 50 are arranged in a shifted manner in the Y direction. A gap is not formed in the X direction of the exposure area. The support 60 has a square pipe shape in cross section, and is fixed to the apparatus main body by bolts (not shown) using holes 52 provided in left and right mounting seats 51 provided at both ends. The support 60 is made of a material having a very small linear expansion coefficient (for example, about 1 × 10 ⁻⁶ [1 / ° C]). In order to maintain the exposure accuracy, the exposure apparatus is usually used in an environment in which the temperature is controlled so that the ambient temperature does not change.

JP 2004-039871 A

However, the smaller the allowable temperature range of the ambient temperature, the more complicated the management becomes.

For example, when the outer diameter of the holder 50 is 80 mm, the exposure accuracy may be reduced by about 2 μm even if the temperature is changed by 1 ° C.

An object of the present invention is to provide an exposure apparatus that can maintain exposure accuracy even when the ambient temperature changes.

The present inventor has found that the cause of the reduction in exposure accuracy is due to the extension of the holder 50 as will be described later.

Based on the above knowledge, the present invention holds the projection imaging lens that emits the cross-sectional area of incident light by enlarging or reducing it at a predetermined magnification, and holding the projection imaging lens in the holder. In an exposure apparatus in which a plurality of arrangements are arranged in a direction perpendicular to the moving direction of an object and supported by a support, and the support is held by the apparatus main body, the support has a first linear expansion coefficient and a linear expansion coefficient of β. A second support, the holder is held by the first support, and the second support is arranged in a direction perpendicular to the moving direction of the object to be exposed and arranged in the moving direction of the object to be exposed. The first support is supported by the support and the second support is fixed to the apparatus main body, the linear expansion coefficient of the holder is α, and the projection imaging lens Α, β, c, n where c is the distance from the first support of the pupil of the lens and c is the length from the device main body fixing position of the second support to the first support support position. Satisfies the expression cα≈nβ.

Even if the ambient temperature changes, the exposure accuracy can be maintained. Moreover, since the allowable range of the ambient temperature can be increased, temperature management becomes easy.

FIG. 1 is a plan view of a support in an exposure apparatus according to the present invention, and FIG. 2 is a diagram for explaining the principle of the present invention.

First, the principle of the present invention will be described with reference to FIG.

The distance in the optical axis direction of the pupil A0 from the upper end (incident side) of the projection imaging lens 30 is a, and the distance from the pupil A0 to the lower end (exit side) of the projection imaging lens 30 is b.

Now, it is assumed that the pupil A0 moves to the point A1 due to the change in the ambient temperature. If the distance between the pupil A0 and the point A1 is m, and the distance from the point B to the point C is K, the distance K is obtained by Equation 1. K = (a + b) m / a (Formula 1)

That is, for example, when the projection imaging lens 30 is a 3 × magnification lens system (b = 3a), the distance c from the support 60 to the pupil A0 is 40 mm, and the holder 50 is made of aluminum, the ambient temperature Is raised by 1 ° C. Now, assuming that the linear expansion coefficient αal of aluminum is 20 × 10 ⁻⁶ [1 / ° C], K is 2.4 μm. When the arrangement of the holders 50 is as shown in FIG. 5, the pupils of the adjacent holders 50 move in opposite directions. As a result, the exposure result in the Y direction of the adjacent exposure region is deviated by about 5 μm from the other as a reference. Since the support 60 does not extend in the X direction, adjacent exposure areas do not overlap.

Next, the present invention will be described.

In FIG. 1, a support 60 is composed of a pair of supports 60A and a pair of supports 60B, which are fixed to each other by bolts not shown. The hole 52 is positioned at the center of the support 60A. The support 60A is made of a material having a very small linear expansion coefficient (about 1 × 10 ⁻⁶ [1 / ° C]). On the other hand, the support 60B is made of iron.

Now, the material of the holder 50 is aluminum having a linear expansion coefficient αal = 20 × 10 ⁻⁶ [1 / ° C], the linear expansion coefficient αfe of the support 60B is αfe = 10 × 10 ⁻⁶ [1 / ° C], and the distance c Is 40 mm. Further, it is assumed that the total length of the support 60B is 160 mm (that is, n = 80 mm), and the ambient temperature has increased by 1 ° C.

Here, paying attention to the holder 50A, the pupil A0 moves downward in the figure of 0.8 μm. On the other hand, the end of the support 60B moves upward in the figure of 0.8 μm with respect to the hole 52 as the support 60A extends as the temperature rises. As a result, even if the ambient temperature increases by 1 ° C., the position of the pupil A0 does not change. In this case, it is clear that the position of the pupil A0 does not change even when the change amount of the ambient temperature is another temperature t ° C.

For example, even if the length of L is 88 mm, the shift amount can be reduced to 1/10 of the conventional amount.

In general, the distance from the support A of the pupil A0 is c, the linear expansion coefficient of the holder 50 is α, the length n from the device fixing point of the support B to the support A, the linear expansion coefficient of the support B is β Where c, α, n, and β have the relationship of Equation 2.

cα = nβ (Formula 2)

Therefore, if any three values of c, α, n, and β in Equation 2 are determined, the remaining one value can be determined.

It is a top view of the support in the exposure apparatus which concerns on this invention. It is a figure explaining the principle of this invention. It is a block diagram of the conventional exposure apparatus. It is a side view of a holder. It is explanatory drawing of a prior art. It is explanatory drawing of a prior art.

Explanation of symbols

6 Substrate (object to be exposed)
30 Projection Imaging Lens 50 Holder 60A First Support 60B Second Support A0 Pupil of Projection Imaging Lens c Distance n Length from Device Body Fixing Position of Second Support to First Support Support Position α Holder 50 Linear expansion coefficient of the second support linear expansion coefficient

Claims (1)

The projection imaging lens for emitting the cross-sectional area of incident light by enlarging or reducing at a predetermined magnification is held by the holder, and the holder holding the projection imaging lens is held in a direction perpendicular to the moving direction of the object to be exposed. In an exposure apparatus in which a plurality of supports are supported by a support and the support is held in the apparatus main body,

The support is composed of a first support having a very small coefficient of linear expansion and a second support having a coefficient of linear expansion of β,

The holder is held by the first support and arranged in a direction perpendicular to the moving direction of the object to be exposed,

The first support is supported by the second support arranged in the moving direction of the object to be exposed and the second support is fixed to the apparatus main body,

The linear expansion coefficient of the holder is α, the distance of the pupil of the projection imaging lens from the first support is c, and the length of the second support from the apparatus body fixing position to the first support support position An exposure apparatus characterized in that α, β, c, n satisfy the expression cα≈nβ where n is n.

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