TWI649632B - Exposure device and exposure method - Google Patents

Abstract

An exposure device and exposure method are provided, which can achieve high efficiency and long life of a spatial light modulation element.

The exposure device (100) includes: a microlens array (142) that collects light from a light source is arranged in an array, and the light to be collected by the microlens array (142) is modulated The spatial light modulating element (digital micro-mirror device) (12) in which the pixel portion is arranged, and the first imaging optics that image the light collected by the microlens array (142) in the spatial light modulating element (12) System (143), and a second imaging optical system (16) that images light modulated by the spatial light modulation element (12) on the photosensitive material.

Description

Exposure device and exposure method

The present invention relates to an exposure device and an exposure method for passing light modulated by a spatial light modulation element through an imaging optical system and imaging an image generated by the light on a predetermined surface.

In recent years, it has been proposed to pass the modulated light using a spatial light modulation device such as DMD (Digital Micromirror Device, Japan (registered trademark)) and the like through the projection optical system, and place the image generated by the light on the photosensitive layer (photoresist layer) ) Exposure device for imagewise exposure. In this way, the exposure device using the spatial light modulation element is called a DI (direct image: direct drawing) exposure device.

Such a DI exposure device has the technology of Patent Document 1, for example. This DI exposure device is provided with a plurality of exposure heads, which are provided with: a spatial light modulation element (DMD), a first projection optical system, a microlens array (MLA), and a second projection optical system. In addition, the DI exposure device has a configuration in which light modulated by DMD is projected on the MLA through the first projection lens, and light transmitted through the MLA is projected on a predetermined light irradiation surface through the second projection lens. Here, MLA is a microlens corresponding to each pixel portion of the DMD, and the position of each pixel matching the DMD is arranged such that Array lens.

[Conventional Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-305663

The technique of Patent Document 1 described above is to irradiate the light from the light source on the entire DMD. The DMD has a configuration in which micro-mirrors (micro-mirrors) are arranged in a two-dimensional shape, and there is a micro gap between adjacent micro-mirrors. Therefore, if the light is irradiated to the entire DMD, the light is also irradiated to the gap. However, the light irradiated on the gap between the micro-mirrors does not contribute to spatial modulation, so it becomes a factor of a decrease in device efficiency. The light from the light source uses, for example, ultraviolet light (UV light). When such UV light is irradiated onto the DMD substrate from the gap, it also causes a reduction in the life of the device.

Here, the subject of the present invention is to provide an exposure apparatus and an exposure method, which can achieve high efficiency and long life of the spatial light modulation element.

In order to solve the above-mentioned problems, an aspect of the exposure apparatus of the present invention includes: a microlens array for collecting light from a light source is a microlens array arranged in an array; of The spatially variable tone portion in which the light-tuned pixel portion is arranged, the first imaging optical system that images the light collected by the microlens array in the spatially light-modulated portion, and the spatially light-modulated portion The second imaging optical system where the modulated light is imaged on the photosensitive material.

Thus, by collecting light from the light source through the microlens array (MLA), the light collected by the MLA can be imaged in the spatial light modulation section. That is, the light collected by MLA can enter the spatial light modulation portion without loss. Therefore, the efficiency of spatial modulation can be improved. In addition, the light collected by the MLA is not irradiated to the substrate that does not contribute to spatial modulation, for example, the spatial light modulation section. Therefore, the deterioration of the element can be suppressed, and the life can be increased.

Further, in the above-mentioned exposure device, the spatial light modulation section is a digital micro-mirror device, and the pixel section may be a micro-mirror corresponding one-to-one with the micro lens.

In this way, the spatial light modulation unit can efficiently use the light from the light source as the exposure light by using a digital micromirror device (DMD) with high light utilization efficiency. Moreover, because the DMD micro-mirrors and the MLA micro-lenses are in one-to-one correspondence, the light collected by the MLA is imaged on the DMD micro-mirrors, so the interference between pixels can be suppressed and the extinction ratio can be reduced. .

Further, with the above-mentioned exposure device, the first imaging optical system is a beam spot-shaped light collected by each microlens of the microlens array on the corresponding micromirror, respectively, by It is also possible to image the beam spot with a smaller mirror size. So, because in the micro On the mirror, light with a beam spot size smaller than the size of the micro-mirror is imaged, so it is possible to reliably prevent the light from entering the gap between the micro-mirrors.

Further, with the above-mentioned exposure device, the second imaging optical system may be an enlarged imaging optical system. In this way, by constructing a configuration in which the light modulated by the spatial light modulation portion is enlarged and imaged on the photosensitive material, the resolution requirements can be appropriately met by adjusting the magnification. Moreover, the high sharpness of the image projected on the photosensitive material can be maintained, and the image can be enlarged.

Furthermore, for the above-mentioned exposure device, the first imaging optical system may be a reduced imaging optical system. In this way, by forming a structure in which the light collected by MLA is reduced and imaged in the spatial light modulation section, MLA with a relatively large spot size can be used. Therefore, the manufacture of MLA becomes easy.

Further, in one aspect of the exposure method of the present invention, the light from the light source is collected by a microlens array in which the microlenses are arranged in an array, and the light is collected by the microlens array The light is imaged in the spatial light modulation part where the pixel parts are arranged, and the light modulated by the spatial light modulation part is imaged on the photosensitive material.

As a result, the light collected by the MLA can enter the spatial light modulation portion without loss, and the efficiency of spatial modulation can be improved. In addition, the light collected by MLA is not irradiated to a substrate that does not contribute to spatial modulation, for example, a substrate of a spatial light modulation section, so that deterioration of the element can be suppressed, and a long life can be achieved.

According to the present invention, the light collected by the microlens array can enter the spatial light modulation portion without loss. Therefore, high efficiency and long life of the spatial light modulation section can be achieved.

W‧‧‧Workpiece

10‧‧‧Exposure head unit

11‧‧‧Exposure head

12‧‧‧DMD

13‧‧‧Light Source Department

14‧‧‧incident optics

15‧‧‧Mirror

16‧‧‧Second Imaging Optics Department

20‧‧‧Department of Transportation

21‧‧‧ stage

22‧‧‧Guide

23‧‧‧Electromagnet

30‧‧‧Settable

31‧‧‧ Gate (Dragon Gate)

32‧‧‧foot

40‧‧‧Sensor

51‧‧‧Exposure area

52‧‧‧Exposure completed area

100‧‧‧Exposure device

111‧‧‧Exposure head

113‧‧‧Light Source Department

114‧‧‧ Department of Optics

115‧‧‧Mirror

116‧‧‧Imaging lens

117a‧‧‧Shading member

118‧‧‧Imaging lens

121‧‧‧SRAM unit (memory unit)

122‧‧‧Micromirror

131‧‧‧Laser shooting department

141‧‧‧ Department of Lighting Optics

142‧‧‧Microlens Array (MLA)

143‧‧‧ First Imaging Optics Department

[Figure 1] A schematic configuration diagram of an exposure apparatus of this embodiment.

[Figure 2] A diagram showing the main part of the exposure head unit.

[Figure 3] A partially enlarged view showing the configuration of the DMD.

[Figure 4] A perspective view showing a schematic configuration of an exposure head.

[Figure 5] An optical layout diagram showing the configuration of the exposure head.

[Figure 6] A diagram showing the state of a beam spot irradiated on a DMD surface.

[Figure 7] An optical layout diagram showing the structure of a conventional exposure head.

[Figure 8] A diagram showing the state of light irradiated on a conventional DMD surface.

[Figure 9] A diagram showing the configuration of a conventional MLA plane.

Hereinafter, embodiments of the present invention will be described based on the drawings.

Fig. 1 is a schematic configuration diagram showing an exposure apparatus of this embodiment.

The exposure device 100 passes light modulated by a spatial light modulating section (spatial light modulating element) through an imaging optical system, and images an image generated by the light on a photosensitive material (photoresist layer) to expose the person. This exposure device, because The image is formed directly by the spatial light modulation element, so no mask (or grating) is required, and it is called a DI (direct image: direct drawing) exposure device.

The exposure apparatus 100 is provided with the exposure head unit 10 and the conveyance system 20 which conveys the board | substrate (workpiece) W which is an exposure object, and the thick-plate-shaped installation stand 30 which installed the exposure head unit 10 and the conveyance system 20. Here, the work W is, for example, a resin printed circuit board coated with a photoresist layer.

The exposure head unit 10 is fixed to a gate-shaped gate (gantry) 31 that spans the installation table 30 across the installation. Each end of the gate 31 is fixed to the side of the installation table 30. Moreover, the installation table 30 is supported by a plurality of (for example, four) leg portions 32.

The conveyance system 20 is provided with a flat-plate-like stage 21 that suction-holds the workpiece W by a method such as vacuum suction, two guides 22 extending in the moving direction of the stage 21, and a stage 21 The electromagnet 23 constitutes an example of the moving mechanism. Here, the moving mechanism is a linear motor stage. The linear motor stage is to float the moving body (stage) by air on a flat platen (pressing cylinder) provided with salient poles of ferromagnetic body in a lattice shape, and add magnetic force outside the moving body, by moving A mechanism that changes the magnetic force between the salient poles of the body and the pressure plate (pressure cylinder) to move the moving body (stage). In addition, the above-mentioned moving mechanism may be a mechanism using, for example, a ball screw.

The stage 21 is arranged so that its longitudinal direction faces the direction of movement of the stage, and is supported so as to be able to reciprocate while the straightness is compensated by the guide 22.

In this specification, the moving direction of the stage 21 is set to the X direction, the horizontal direction perpendicular to the X direction is set to the Y direction, and the vertical direction is set to the Z direction. The workpiece W has a square shape, and is held on the stage 21 from one side toward the X direction and the other side toward the Y direction. In addition, in the following description, the X direction is the longitudinal direction of the workpiece W, and the Y direction is the width direction of the workpiece W.

The movement path of the stage 21 is designed to pass directly under the exposure head unit 10, and the conveyance system 20 conveys the workpiece W toward the irradiation position of the light generated by the exposure head unit 10 and passes the irradiation position. In the process passed here, the pattern of the image formed by the exposure head unit 10 is exposed to the workpiece W.

The exposure head unit 10 is provided on one side of the gate 31 in the X direction, and a plurality (for example, two) sensors 40 that detect the leading end and the trailing end of the workpiece W are provided on the other side. That is, the shutter 31 provided with the exposure head unit 10 and the sensor 40 is fixedly arranged upstream of the movement path of the stage 21. In addition, the exposure head unit 10 and the sensor 40 are connected to a controller (not shown) that controls these.

As shown in FIG. 2, the exposure head unit 10 includes a plurality of (fourteen in FIG. 2) exposure heads 11 arranged in a substantially array of m rows and n columns. Each exposure head 11 is a built-in spatial light modulation element, and irradiates light with a pattern set in advance. The exposure area 51 generated by each exposure head 11 has a rectangular shape with short sides in the sub-scanning direction. Therefore, along with the movement of the stage 21, a strip-shaped exposure completion area 52 is formed in each exposure head 11 in the workpiece W.

The spatial light modulation element uses, for example, a digital micromirror device (DMD) 12 shown in FIG. 3. The DMD 12 has a configuration in which a minute mirror (micromirror) 122 of a 13 μm angle constituting each pixel (pixel) is arranged in a two-dimensional manner on a memory cell (for example, SRAM cell) 121. The number of arranged micromirrors 122 is, for example, 1024 × 768. In each pixel, a rectangular micromirror 122 supported by a pillar is provided in the uppermost portion, and a material having a high reflectance such as aluminum is vapor-deposited on the surface of the micromirror 122. In addition, a minute gap of 1 μm or less exists between adjacent micromirrors 122.

When the digital signal is written into the SRAM cell 121 of the DMD 12, each micromirror 122 supported on the pillar is inclined to any one of ± α degrees with respect to the substrate side on which the DMD 12 is arranged diagonally. In this way, by controlling the tilt of each micro-mirror 122, the light incident on the DMD 12 is reflected in the tilt direction of each micro-mirror 122.

The on-off control of each micromirror 122 is performed by a controller (not shown) connected to the DMD 12. This controller controls the angle of each micromirror 122 of the DMD 12 in such a manner that the desired pattern is formed on the workpiece W. That is, the angle of each micromirror 122 of the DMD 12 is selectively controlled according to the pattern of the portrait to be formed.

As shown in FIG. 4, the exposure head 11 includes a light source unit 13, an incident optical system 14, and a mirror 15 on the light incident side of the DMD 12.

The light source unit 13 is a light source including a light bulb that emits laser light with a wavelength of 400 nm, a semiconductor laser (laser diode), or the like. This light source 13. An optical fiber equipped to guide the output light of the light source. Here, as the optical fiber, a fiber such as quartz can be used. The emission ends (light emitting points) of the optical fiber are arranged in a row along the direction corresponding to the longitudinal direction of the exposure area 51, and constitute a laser emission portion 131.

The incident optical system 14 is an optical system for incident laser light emitted from the light source unit 13 on the DMD 12. In addition, in FIG. 4, the incident optical system 14 is shown roughly.

The mirror 15 reflects the laser light emitted from the incident optical system 14 toward the DMD 12.

As shown in FIG. 5, the incident optical system 14 includes an illumination optical system 141, a microlens array (MLA) 142, and a first imaging optical system 143.

The illumination optical system 141 is constituted by an integrator lens, a collimating lens, a lens, etc., and the laser light emitted from the laser light emitting unit 131 of the light source unit 13 enters the MLA 142 as parallel light. MLA142 is an optical component in which a large number of minute convex lenses (microlens elements) are arranged in a two-dimensional shape. Each microlens element corresponds to each micromirror 122 of the DMD 12 in one-to-one correspondence. The first imaging optical system 143 is a reduced imaging optical system that images light condensed in a spot shape by the MLA 142 in the DMD 12 for example in a reduced manner. That is, the DMD 12 and the MLA 142 are arranged so that light emitted from one microlens element is collected on a specific one of the micromirrors 122 through the first imaging optical system 143 so as to converge.

The exposure head 11 is provided with a second imaging optical system 16 on the light exit side of the DMD 12 as shown in FIGS. 4 and 5. Second imaging light The department 16 is an enlarged imaging optical system that projects an image from the DMD 12 on the workpiece W at a magnification of 5 times, for example.

A controller (not shown) of the exposure device 100 memorizes digital data (original data) of an image (exposure pattern) to be formed, sends a control signal to the conveyance system 20, and transfers the stage 21 on which the workpiece W is placed Move by the specified speed. Moreover, at the same time, the controller sends a control signal toward the DMD 12, so that the angle of each micro-mirror 122 is controlled by a prescribed time point and sequence in a manner of forming an exposure pattern on the workpiece W according to the original data. As a result, when the workpiece W coated with the photoresist layer passes through the exposure area 51, an exposure pattern based on the original data is formed on the workpiece W.

As described above, the exposure apparatus 100 in the present embodiment has: the MLA 142 is arranged in the front stage (light incident side) of the DMD 12, passes through the first imaging optical system 143, and beams of light are spotted on the micro mirror 122 of the DMD 12 The composition of light collection. MLA142 is to collect the light from the light source unit 13 which is made into parallel light by each microlens. The first imaging optical system 143 is the beam spot to be collected by the MLA142 as shown in FIG. 6 The shaped light (laser beam B) is imaged in each micromirror 122 of the DMD 12. At this time, the laser beam B is collected by the micromirror 122 having an angle of 13 μm, for example, to a diameter of about 2.4 μm. In this manner, since the beam-shaped light is collected on the micro-mirror 122 of the DMD 12, the loss of light can be suppressed, and the element efficiency can be improved. Hereinafter, this point will be described in detail.

FIG. 7 is a diagram showing an exposure head 111 of a conventional configuration in which MLA is arranged on the light exit side of the DMD. As shown in FIG. 7, the exposure head 111 is on the light incident side of the DMD 112 and includes: a light source section 113, and the illumination optics 114, and the mirror 115. Furthermore, the exposure head 111 is on the light exit side of the DMD 112, and includes a first imaging lens 116, an MLA 117, and a second imaging lens 118. Here, the light source unit 113, the illumination optical system 114, and the mirror 115 have the same configuration as the light source unit 13, the illumination optical system 141, and the mirror 15 shown in FIG. In addition, the first imaging lens 116 and the second imaging lens 118 are, for example, enlarged projection lenses. In addition, the first imaging lens 116 may be an equal-magnification projection lens or a reduction projection lens.

In this exposure head 111, the illumination optical system 114 converts the light from the light source section 113 into parallel light, and enters this into the DMD 112. That is, as shown in FIG. 8, the light from the light source (laser beam B) is irradiated on the entire surface of the DMD 112. As described above, since there is a minute gap between the adjacent micro-mirrors 122, the laser beam B incident to this gap is absorbed by the substrate material of the DMD 112 and becomes a light loss. It is also possible that the substrate material of the DMD112 will deteriorate the device by absorbing the laser beam B, and the temperature rise of the DMD112 will promote the deterioration of the device.

In this regard, in this embodiment, as shown in FIG. 6, since the spot-shaped light is collected on the micro-reflector 122 of the DMD 12, the laser beam B will not be irradiated on the micro-reflector 122. The gap between. Therefore, it is possible to suppress the loss caused by the light irradiated out of the surface of the micromirror 122, and it is possible to increase the light output generated by the DMD 12 in this portion. In this way, the element efficiency of the DMD12 can be improved.

Further, since the substrate material of the DMD 12 can be suppressed from absorbing the laser beam B, the deterioration of the element can be suppressed. Therefore, one can seek Long life of DMD12. As a result, the exchange frequency of the DMD12 can be reduced, and the processing capacity can be improved.

In addition, when the exposure head 111 shown in FIG. 7 is arranged with the MLA 117 on the light exit side of the DMD 112, high accuracy is required in the alignment of the DMD 112 and the MLA 117. This is because the micromirrors constituting the DMD112 and the microlenses constituting the MLA117 have a one-to-one relationship, so it is necessary to correctly reflect the light reflected by one micromirror toward the corresponding one microlens. When light from one micromirror enters the complex microlens, the resolution performance will decrease and the extinction ratio will decrease.

In this regard, in this embodiment, the light that has passed through one microlens as described above is collected to a diameter of about 2.4 μm and is imaged on the micromirror 122 at an angle of 13 μm. Therefore, the accuracy required for the positional alignment of the DMD12 and MLA142 is lower compared to the above-mentioned conventional configuration, and the positioning operation becomes easy. In addition, since the conventional configuration does not allow light from one micro-reflector to enter the plural microlenses, it is possible to prevent degradation of the resolution performance and improve the extinction ratio.

However, although the MLA has a configuration in which a plurality of microlenses are arranged, the light incident on the junction with the adjacent microlenses becomes mysterious. Therefore, in order to prevent this, as shown in FIG. 9, it is considered that a light shielding member 117a is provided on the light incident side of the MLA 117 to block the incidence of light toward the junction. Here, as the light-shielding member 117a, a light-shielding film containing, for example, a chromium-based material can be used. That is, only light passing through the opening formed by the light shielding member 117a is incident on the MLA 117, which contributes to exposure. In this case, in order not to reduce the efficiency of the optical system, it is necessary to The MLA117, such as a joint part, blocks light in a range where the light collecting performance is insufficient, and sets the opening as large as possible.

However, as in the exposure head 111 shown in FIG. 7, when the light from each micromirror of the DMD 112 is incident on the corresponding microlens structure of the MLA117, when the above-mentioned opening is enlarged, the interference between adjacent pixels It may happen. Since the DMD112 and MLA117 have an upper limit on the positional alignment accuracy, the opening cannot be enlarged to a certain degree or more. That is, as shown in FIG. 9, through the opening formed by the light-shielding member 117a, the area of light transmitted through the microlens, that is, the light effective area A, has to be narrower than the light transmission area B of the microlens. Therefore, light loss occurs in MLA117. For example, when the cell size of the microlens is 39.73 μm angle and the size of the opening is 37 μm angle, light with an area ratio of 30% or more is absorbed by the shading member, which is directly a loss of light.

In this regard, in this embodiment, since the spot-shaped light collected by the MLA 142 is imaged on the micro-mirror of the DMD 12, interference between adjacent pixels can be suppressed. Moreover, in MLA142, the light from the light source is incident all over. In other words, it is not a configuration that selectively enters light into each microlens of MLA142. Therefore, it is not necessary to provide the light-shielding member corresponding to the above-mentioned light-shielding member 117a to the MLA 142, or only to shield the MLA 142 from a range in which the light-collecting performance is insufficient, and it is possible to use a light-shielding member with the opening as large as possible. When the shading member is eliminated, the output can be improved by about 40%.

As described above, in the conventional configuration in which MLA117 is arranged on the light exit side of DMD112, MLA117 and DMD112 are respectively different The light is kicked away and becomes a large loss of light. In this regard, in this embodiment, by disposing the MLA 142 on the light incident side of the DMD 12, it is possible to prevent the loss of light caused by being kicked off, and the efficiency of the optical system can be improved. Therefore, the light intensity in the exposed surface can be enhanced, and the processing capacity can be improved.

And in this embodiment, since the light loss can be reduced, the light intensity in the exposed surface is the same as the conventional device shown in FIG. 7, and the light from the light source can be weakened compared to the conventional device strength. That is, the intensity of light incident on the DMD may be weaker than that of the conventional device. Therefore, the load on the DMD surface and the DMD hinge can be reduced, and the temperature rise of the DMD portion can be reduced. Therefore, the deterioration of DMD can be suppressed. As a result, the exchange frequency of DMD can be reduced, and the maintenance cost can be reduced.

In addition, the exposure device 100 in the present embodiment is configured to image the light collected by the MLA 142 on the DMD 12, so the first imaging optical system 143 is provided. Since the first imaging optical system 143 is a reduced imaging optical system, the light collected by the MLA 142 is reduced and imaged on the DMD 12. Therefore, MLA142 with a relatively large spot size can be used, and the manufacture of MLA142 is easy.

Furthermore, the exposure apparatus 100 in this embodiment is provided with the second imaging optical system 16 in order to image the light modulated by the DMD 12 on the exposure surface. Since the second imaging optical system 16 is an enlarged imaging optical system, the light modulated by the DMD 12 is enlarged to be imaged on the exposure surface. It is collected on the micromirror 122 of the DMD12 to a diameter of about 2.4 μm, for example After the light is modulated by the DMD 12, it is enlarged by the second imaging optical system 16, for example, 5 times, and becomes a beam spot with a diameter of 12 μm on the exposure surface. At this time, by adjusting the magnification of the second imaging optical system, the beam spot size in the exposure surface can be adjusted. Therefore, the resolution requirements can be appropriately met.

(Modification)

In the above embodiment, the spatial light modulation element has been described as the case where a reflective spatial light modulation element, that is, DMD12 is used, but a transmissive spatial light modulation element such as liquid crystal may be used. However, since the DMD with high light utilization efficiency is used as the spatial light modulation element, the light from the light source can be efficiently used as the exposure light, which is preferable.

In addition, in the above embodiment, although the first imaging optical system has explained the case of using the reduced imaging optical system, the first imaging optical system may be an equal-magnification imaging optical system, or the imaging optical system may be enlarged. In addition, although the second imaging optical system has explained the case of using an enlarged imaging optical system, the second imaging optical system may be an equal-magnification imaging optical system, or a reduced imaging optical system.

Claims (4)

An exposure apparatus characterized by comprising: a microlens array that collects light from a light source is a microlens array arranged in an array, and a pixel portion to be modulated by the light collected by the microlens array The arranged spatial light modulation part, the first imaging optical system that images the light collected by the microlens array in the spatial light modulation part, and the light to be modulated by the spatial light modulation part in the photosensitive material The second imaging optical system imaged above, the spatial light modulation section is a digital micro-mirror device, the pixel section is a micro-mirror corresponding one-to-one with the micro lens, and the first imaging optical system is reduced Imaging optics. An exposure apparatus as claimed in item 1 of the patent application, wherein the first imaging optical system is a beam spot-shaped light collected by each microlens of the microlens array, reflected in the corresponding microreflection On the mirror, the image is formed by the beam spot size smaller than the size of the micro-mirror. An exposure apparatus as claimed in item 1 or 2 of the patent application, wherein the aforementioned second imaging optical system is an expanded imaging optical system. An exposure method characterized by collecting light from a light source through a microlens array arranged in an array in a form of microlenses, reducing the light collected through the microlens array, and having The spatial light modulation part of the digital micro-mirror device of the one-to-one corresponding micromirror of the microlens is imaged, and the light modulated by the spatial light modulation part is imaged on the photosensitive material.