JP7427352B2 - exposure equipment - Google Patents

Description

The present invention relates to an exposure apparatus that exposes a pattern onto a substrate.

2. Description of the Related Art In order to form wiring patterns and the like on a printed circuit board, a direct drawing exposure apparatus is known that is provided with a plurality of semiconductor lasers (hereinafter referred to as LD) as a light source and directly exposes the board to light without using a mask. In such a direct writing exposure device, even if a large number of LDs are lined up and the light emitted from each light source is attempted to uniformly irradiate the object to be illuminated, the directivity of the light emitted from the illumination optical system approaches a Gaussian distribution, resulting in poor irradiation. The illumination may be strong near the center of the area and weak at the periphery, or conversely, the illumination may be weak near the center and strong at the periphery. If the illumination light is not uniform in this way, exposure will be poor and throughput will be reduced.

In order to prevent such exposure defects, there is a technique to uniformize the exposure illumination light by providing an integrator or diffuser, as disclosed in FIG. 7 of Patent Document 1, but it is possible to In order to make the light enter the integrator, extremely troublesome fine adjustments are required, which takes time. Therefore, if fine adjustment is not performed, there is a problem that the exposure illumination light becomes non-uniform due to insufficient adjustment of the light incident on the integrator.

JP 2004-039871

An object of the present invention is to provide an exposure apparatus that can solve the above problems and improve the uniformity of exposure illumination light on an irradiated surface.

In order to solve the above problems, among the inventions disclosed in this application, a typical exposure apparatus includes an exposure light source that emits illumination light for exposing a substrate and includes a plurality of semiconductor lasers; In an exposure apparatus comprising a two-dimensional spatial modulator into which light is incident, and a stage for scanning and exposing the substrate by moving the substrate with respect to illumination light, an optical filter disposed on the optical axis of the illumination light; the optical filter has a transmittance that changes in a first direction within a plane perpendicular to the optical axis; The transmittance does not change in the second direction perpendicular to the first direction, and the transmittance is the highest at the center position in the first direction, and the transmittance decreases toward the periphery.

According to the present invention, it is possible to improve the uniformity of the exposure illumination light on the irradiation surface.

1 is an overall configuration diagram of an exposure apparatus according to an embodiment of the present invention. 2 is a diagram for explaining the illumination optical system in FIG. 1. FIG. 2 is a diagram for explaining an optical filter in FIG. 1. FIG. FIG. 3 is a diagram for explaining integrated illuminance when no optical filter is provided. It is a figure for explaining integrated illuminance when an optical filter is provided. FIG. 6 is a diagram for explaining a case where the peak value of integrated illuminance shifts when no optical filter is provided. FIG. 6 is a diagram for explaining the integrated illuminance when the optical filter is moved and positioned in the X direction. It is a figure for explaining the transmittance when an optical filter is provided and rotated.

Embodiments of the present invention will be described below along with examples with reference to the drawings. In addition, in the following description, each equivalent part is given the same code|symbol, and description is abbreviate|omitted.

FIG. 1 is an overall configuration diagram of a direct drawing exposure apparatus according to an embodiment of the present invention. 1 is an exposure lighting unit. Reference numeral 2 denotes an illumination optical system, from which exposure illumination light 4 is emitted in the direction indicated by an optical axis 4a and transmitted through an optical filter 3, which will be described later, is incident on a two-dimensional spatial modulator 6 located above by a mirror 5. Ru. Here, since a digital mirror device is used as the two-dimensional spatial modulator 6, the two-dimensional spatial modulator will be referred to as DMD.

In the DMD 6, a large number of movable micromirrors are arranged in a matrix in the XY plane. When an ON/OFF signal is sent to each micromirror from a control device 7, which will be described later, the micromirror that receives the ON signal tilts at a certain angle, reflects the incident exposure illumination light, and makes it enter the first projection lens 8. . Further, the exposure illumination light 4 reflected by the micromirror in the OFF state does not enter the first projection lens 8 and does not contribute to exposure. The exposure illumination light transmitted through the projection lens 8 enters the microlens array 9. A microlens is arranged at each position of the microlens array 9 where an enlarged image (or reduced image) of the micromirror of the DMD 5 is formed. The exposure illumination light 4 (the exposure illumination light coming from the micromirror in the ON state) that enters each microlens almost perpendicularly enters the second projection lens 10, and the exposure illumination light 4 that exits the second projection lens 10 forms an exposure pattern within the irradiation area 12 on the substrate 11. In this case, an exposure pattern is scanned and exposed on the substrate 11 by exposing the substrate 11 while moving it with respect to the exposure illumination unit 1 along the Y direction, which is the scanning direction.

Reference numeral 7 denotes a control device realized by, for example, a program-controlled processing device, which controls the operations of the illumination optical system 2, DMD 6, and stage 13 in the exposure illumination unit 1. Reference numeral 14 denotes a stage drive unit that moves the stage 13 in the X, Y, and Z directions in response to control commands from the control device 7. Reference numeral 15 denotes illuminance detection means, which is fixed on the stage 13 and is, for example, an optical sensor such as a CCD type line sensor or an illuminance meter. The width of the light receiving section of the illuminance detection means 15 in the X direction is set to be sufficiently wider than the width of the irradiation area 12 in the X direction, and is controlled on and off in response to a control command from the control device 7 to detect the exposure illumination light 4. If so, a detection signal is sent to the control device 7.

FIG. 2 is a diagram for explaining the illumination optical system 2 in FIG. 1. Reference numeral 16 denotes an exposure light source, which is constructed by two-dimensionally arranging blue and violet LDs on a substrate, which emit light with a wavelength of around 405 nm (380 to 420 nm) with an output of about 400 mW. The light emitted from each LD is transmitted through a diffuser 18 by a condensing lens (condensing optical system) 17, and then enters an optical integrator 19. The diffuser 18 is a modulator that changes the wavefront, and is composed of a glass disk that is rotated by driving a directly connected motor. The light transmitted through the optical integrator 19 passes through a condenser lens (collimating lens) 20, is reflected by a mirror 5, and is irradiated onto the DMD 6. The optical integrator 19 is an optical system that spatially decomposes the light beams emitted from a large number of two-dimensionally arranged LDs that are focused by a condensing lens 17 to generate a large number of pseudo secondary light sources and superimpose them for illumination. It is a system. Note that the motors of the exposure light source 16 and the diffuser 18 are controlled by the control device 7.

3(a) and (b) are diagrams for explaining the optical filter 3 disposed near the illumination optical system 2, in which (a) is a plan view seen from the direction of the optical axis 4a, and (b) is a diagram for explaining the optical filter 3 disposed near the illumination optical system 2. FIG. 4 is a diagram showing changes in integrated transmittance in a direction perpendicular to the optical axis 4a. The optical filter 3 has a circular region 21 whose transmittance changes in the X direction, as shown by the broken line in FIG. 3A, and the transmittance of the circular region 21 in the Z direction is all the same.

The cumulative transmittance T of the circular area 21 in the X direction is calculated when the optical filter 3 is provided, the stage 13 is driven, the illuminance detection means 15 is moved in the Y direction, and uniform exposure illumination light 4 with no illuminance unevenness is detected. When the value obtained by integrating the illuminance detection values in each X direction is D1, and the value obtained when the same procedure is performed without providing the optical filter 3 is D2, it is expressed by the following equation (1).
T=(D1/D2)×100 (%) ...(1)
This distribution is symmetrical with respect to the center position X5 of the circular region 21 in the X direction, and increases monotonically from the center position X5 toward the positions X1 and X9.

FIGS. 4A and 4B are diagrams for explaining the integrated illuminance when the optical filter 3 is not provided. FIG. 4(a) is a diagram showing the integrated illuminance, and FIG. 4(b) is an image diagram showing the illuminance distribution of the irradiation area 12. In FIG. 4(b), black indicates a portion with low integrated illuminance, and white indicates a portion with high integrated illuminance. The integrated illuminance is a value obtained by integrating the illuminance in each X direction when the illuminance detection means 15 is moved in the Y direction and the exposure illumination light 4 is detected. The center position xc in the X direction is the highest, and the integrated illuminance decreases toward the position xa and the position xe.

FIGS. 5A and 5B are diagrams for explaining the integrated illuminance of the irradiation area 12 when the optical filter 3 is provided. FIG. 5(a) is a diagram showing the integrated illuminance, and FIG. 5(b) is an image diagram showing the illuminance distribution of the irradiation area 12. By positioning the optical filter 3 near the illumination optical system 2 so that the center 22 of the circular area 21 and the center of the optical axis 4a coincide, the illuminance is adjusted so that the integrated illuminance at the center position xc in the X direction is the highest. The unevenness is well corrected, and a substantially uniform illuminance distribution is realized on the substrate 11 as shown in FIG. 5(b). In this embodiment, a case has been described in which the optical filter 3 has a distribution in which the transmittance increases monotonically from the center position X5 in the X direction of the circular region 21 toward the positions X1 and X9. It is also possible to use an optical filter 3 having a distribution such that the transmittance is highest at position X5 and monotonically decreases from center position X5 toward positions X1 and X9. In this case, it is possible to correct the illuminance distribution of the irradiation area 12 where the center position xc in the X direction is the lowest and the integrated illuminance increases toward the positions xa and xe.

FIGS. 6A and 6B are diagrams for explaining a case where the optical filter 3 is not provided and the position where the integrated illuminance becomes high is shifted from the center position in the X direction. FIG. 6(a) is a diagram showing the integrated illuminance, and FIG. 6(b) is an image diagram showing the illuminance distribution of the irradiation area 12. The position where the cumulative illuminance is highest has shifted from position xc to position xb, and in such a case, even if the optical filter 3 described using FIGS. Cannot be corrected.

FIGS. 7A and 7B are diagrams for explaining the case where the optical filter 3 is provided and the position where the integrated illuminance becomes high is shifted from the center position in the X direction. FIG. 7(a) is a diagram showing the integrated illuminance, and FIG. 7(b) is an image diagram showing the illuminance distribution of the irradiation area 12. By moving and positioning the center position X5 of the optical filter 3 in the X direction with respect to the illumination optical system 2, the uneven illuminance is corrected as shown in FIGS. 7(a) and (b), and a substantially uniform illuminance distribution is achieved. Realized.

FIGS. 8(a) and 8(b) are diagrams for explaining the integrated transmittance when the optical filter 3 is provided and the optical filter 3 is rotated with the center 22 as a reference. FIG. 3B is a plan view seen from the direction of FIG. When the optical filter 3 is rotated 30 degrees clockwise, it is R1, when it is rotated 60 degrees, it is R2, and when it is rotated 90 degrees, it is R3. The case where the optical filter 3 is not rotated is R0, and in this case, the integrated transmittance is equivalent to that in FIG. 3.

When the optical filter 3 is rotated 30 degrees from the position R0, it becomes R1, the center position X5 in the X direction is the lowest, and the integrated illuminance increases toward the positions X1 and X9. Compared to the case where the optical filter 3 is not rotated, it increases relatively gradually from the center position X5 to X1 and X9, so it is applicable when the illuminance is high at the center position X5 and decreases relatively gradually to X1 and X9. can.

When the optical filter 3 is rotated 30 degrees clockwise from the R1 position (60 degrees from the R0 position), it becomes R2, where X3 to X7 are low, and the integrated illuminance is about 2.5% higher toward positions X1 and X9. Become. It can be applied to the exposure illumination light 4 where the illuminance is high from X3 to X7 and gradually decreases from X1 to X9.

When the optical filter 3 is rotated by 30 degrees from the position of R2 (90 degrees from the position of R0), it becomes R3, where X3 to X7 are high and the integrated illuminance decreases by about 9% toward positions X1 and X9. It can be applied to exposure illumination light 4 where the illuminance is low from X3 to X7 and gradually increases from X1 to X9.

According to the above embodiment, by providing the optical filter 3, uniform exposure illumination light 4 can be emitted even when the exposure illumination unit 1 with uneven illuminance is used. Furthermore, by rotating the optical filter 3, it is possible to correct various illuminance irregularities and emit uniform exposure illumination light 4.

In the above-described embodiment, the case where one exposure illumination unit 1 is arranged for the substrate 11 has been described, but two or more exposure illumination units 1 may be provided in the X direction and exposed simultaneously. good. In this case, the area that is exposed at one time increases, making it possible to improve throughput.

Further, the present invention is not limited to the above embodiments, and various modifications are possible, and all technical matters included in the technical idea described in the claims are covered by the present invention.

1 Exposure illumination unit 2 Illumination optical system 3 Optical filter 4 Exposure illumination light 5 Mirror 6 DMD
7 Control device 8 First projection lens 9 Microlens array 10 Second projection lens 11 Substrate

Claims (3)

an exposure light source that emits illumination light for exposing a substrate and includes a plurality of semiconductor lasers; a two-dimensional spatial modulator into which the illumination light is incident; and a two-dimensional spatial modulator that moves the substrate with respect to the illumination light. a stage for scanning exposure; and an optical filter disposed on the optical axis of illumination light between the exposure light source and the two-dimensional spatial modulator, and the substrate is continuously scanned along the scanning direction. In an exposure apparatus that forms an image corresponding to an exposure pattern formed on an irradiation area on the substrate while moving pixel by pixel in the two-dimensional spatial modulator in parallel with the movement;
The optical filter is arranged to rotate around the optical axis,
In an initial state in which the optical filter is not rotated, the transmittance of the optical filter changes in a first direction within a plane perpendicular to the optical axis, but changes in a second direction perpendicular to the first direction. no change in direction,
In the initial state, the integrated transmittance of the optical filter at the center position in the first direction is the lowest, and the integrated transmittance of the optical filter increases toward the periphery,
When the optical filter is rotated by 90 degrees from the initial state, the integrated transmittance of the optical filter is highest at the center position in the first direction, and the integrated transmittance of the optical filter increases toward the periphery. Exposure equipment lowers. When the optical filter is rotated by 30 degrees from the initial state, the integrated transmittance of the optical filter at the center position in the first direction is the lowest, and the integrated transmittance of the optical filter increases toward the periphery. 2. The exposure apparatus according to claim 1, wherein the integrated transmittance of the optical filter increases relatively slowly with respect to the initial state. When the optical filter is rotated by 60 degrees from the initial state, the integrated transmittance of the optical filter in the central region including the center position in the first direction is low, and as it goes from the central region to the outer region. The exposure apparatus according to claim 1 or 2, wherein the integrated transmittance of the optical filter increases gradually.

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