Exposure apparatus

Abstract

Provided is an exposure apparatus capable of improving exposure accuracy while ensuring throughput. An exposure apparatus (100) includes: a reflective liquid crystal modulation apparatus (21, 22); a light source apparatus (10) that illuminates the reflective liquid crystal modulation apparatus (21, 22) with uniformized pulsed laser light in the ultraviolet wavelength region; a projection optical system (30) that images reflected light modulated by the reflective liquid crystal modulation apparatus (21, 22); and a stage (40) that supports an object to be exposed with a pattern imaged by the projection optical system (30).

Description

Technical Field

[0001] This invention relates to an exposure apparatus that uses a laser as a light source, and more particularly to an exposure apparatus that uses a reflective liquid crystal modulation device. Background Technology

[0002] Exposure apparatuses are known to include: an illumination device comprising a scanning device for scanning illumination light, an optical element serving as a holographic recording medium into which the scanning light is incident, a spatial light modulator illuminated by light from the optical element, and an imaging optical system for imaging an object with light modulated by the spatial light modulator. In the apparatus of Patent Document 1, for example, the use of LCOS as a spatial light modulator is proposed.

[0003] However, in exposure using scanning devices, the scanning time is required. If the scanning is not close enough, the uniformity of illumination cannot be improved, and there is a limit to increasing throughput while ensuring exposure accuracy.

[0004] As another exposure device, there is a known exposure device that includes: an illumination source, an intensity uniformity optical system, a digital micromirror device for forming a pattern, and a projection lens for projecting the pattern formed by the digital micromirror device (Patent Document 2).

[0005] However, digital micromirror devices (DMMs) suffer from significant in-plane deviations in the tilt angle of the micromirrors, as well as substantial individual differences between devices, making it difficult to ensure uniform in-plane illumination. Furthermore, DMMs struggle with fine-tuning grayscale control; when grayscale is refined, the time-segmented control tends to increase display time, thus limiting the potential for increased exposure throughput. Additionally, DMMs require oblique incident illumination, making the assembly of the optical system challenging.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2012-114358

[0009] Patent document 2: Japanese Patent Application Publication No. 2001-135562. Summary of the Invention

[0010] The present invention was made in view of the above-mentioned background technology, and its object is to provide an exposure apparatus that can improve exposure accuracy while ensuring throughput.

[0011] To achieve the above objectives, the exposure apparatus of the present invention comprises: a reflective liquid crystal modulation device; a light source device that illuminates the reflective liquid crystal modulation device with pulsed laser light in the homogenized ultraviolet wavelength region; a projection optical system that images the reflected light modulated by the reflective liquid crystal modulation device; and a worktable that supports an object to be exposed using the pattern imaged by the projection optical system.

[0012] In the aforementioned exposure apparatus, the reflective liquid crystal modulation device is similarly illuminated with pulsed laser light. The object on the worktable is exposed using the pattern formed by the reflected light modulated by the reflective liquid crystal modulation device and imaged by the projection optics system. Therefore, it is possible to maintain the exposure throughput while achieving high precision in the illumination adjustment of the reflective liquid crystal modulation device. Furthermore, when changing the exposure area while moving the worktable, from the viewpoint of ensuring high-precision worktable movement, there is a certain limit to the movement speed. It is easy to rewrite the pattern of the reflective liquid crystal modulation device for each frame at a speed corresponding to this speed limit.

[0013] According to a specific aspect of the present invention, in the above-described exposure apparatus, exposure is performed at predetermined periodic intervals while the object is moved by a stage, and during the intervals between exposures, a pattern is rewritten on the reflective liquid crystal modulation device. In this case, exposure can be performed while the stage is continuously moved, thereby enabling rapid and high-precision exposure.

[0014] According to another aspect of the invention, different regions of the object are exposed sequentially while the worktable is moved, resulting in overall exposure of the object. In this case, the exposure pattern can be transferred with a spatial resolution higher than the pixel density of a reflective liquid crystal modulation device.

[0015] According to another aspect of the invention, the light source device includes a pulsed laser that generates exposure light with a pulse width that is considered to substantially stop the stage. In this case, short-pulse exposure can be performed using the pulsed laser while stabilizing the movement of the stage, thereby improving the accuracy of the exposure pattern.

[0016] According to another aspect of the invention, overlapping exposure is performed with a predetermined offset less than the pixel pitch. In this case, the resolution can be improved by setting the predetermined offset and combining the overlapping patterns.

[0017] According to another aspect of the present invention, the device comprises: two reflective liquid crystal modulation devices; and a beam splitter that branches and distributes laser light from the light source device to the two reflective liquid crystal modulation devices according to the polarization state, and the beam splitter combines the reflected light modulated by the two reflective liquid crystal modulation devices. In this case, multiple exposures can be performed, and the exposure processing speed can be accelerated.

[0018] According to another aspect of the invention, the beam splitter is a polarization beam splitter, which allows light with different polarization states to be incident on two reflective liquid crystal modulation devices, thereby synthesizing reflected light with different polarization states modulated by the two reflective liquid crystal modulation devices. In this case, laser light from the light source device can be utilized efficiently.

[0019] According to another aspect of the invention, two reflective liquid crystal modulation devices having substantially the same pixel arrangement pattern are configured to produce a predetermined offset in an image synthesized by a polarizing beam splitter. In this case, resolution can be improved by setting the predetermined offset and combining the patterns formed in the two reflective liquid crystal modulation devices.

[0020] According to another aspect of the invention, the offset is specified to be less than or equal to the pixel pitch. In this case, the resolution can be improved by setting the specified offset and combining the patterns formed in the two reflective liquid crystal modulation devices.

[0021] According to another aspect of the present invention, the light source device monitors the energy of the pulsed laser source and the laser light from the pulsed laser source, and cuts off the output of the laser light when a predetermined threshold is reached. In the case of repeated exposures while moving the stage, energy level variations during each exposure can be prevented, and exposure accuracy can be improved as a whole for the repeated exposure pattern.

[0022] According to another aspect of the present invention, a reflective liquid crystal modulation apparatus adjusts the linewidth of a pattern to be exposed on an object by controlling the grayscale of the reflected light. Compared with digital mirror devices, reflective liquid crystal modulation apparatuses can more easily achieve finer grayscale and expand the adjustment range of the pattern's linewidth, enabling high-precision exposure.

[0023] According to another aspect of the invention, a surface observation system is provided that monitors the alignment state of a pattern relative to an object on a worktable, and the surface observation system is capable of observing the pattern on the reflective liquid crystal modulation device and the pattern set on the object on the worktable in an overlapping manner.

[0024] According to another aspect of the invention, there is an autofocus system that monitors the imaging state relative to an object on a worktable. Attached Figure Description

[0025] Figure 1 This is a block diagram illustrating the overall structure of the exposure apparatus according to the implementation method;

[0026] Figure 2 This is a conceptual cross-sectional diagram illustrating the structure of a reflective liquid crystal modulation device;

[0027] Figure 3 This is an illustration of the optical path after the surface observation system is removed;

[0028] Figure 4 This is an explanatory diagram of the optical path after the autofocus system is removed;

[0029] Figure 5 This is a diagram illustrating the structure of the laser output stabilization device incorporated into the light source device;

[0030] Figure 6A and 6B This is a diagram illustrating the operation of the laser output stabilization device;

[0031] Figure 7 This diagram illustrates the basic operation of exposure;

[0032] Figures 8A-8F This is a diagram illustrating the different exposure modes;

[0033] Figure 9 This is a diagram illustrating the method for adjusting line width. Detailed Implementation

[0034] Hereinafter, an exposure apparatus according to an embodiment of the present invention and its operation will be described with reference to the accompanying drawings.

[0035] Reference Figure 1 The exposure apparatus 100 of the embodiment includes a light source device 10, a light modulation unit 20, a projection optical system 30, an object stage 40, a lens stage 50, and a control device 90. The exposure apparatus 100 includes a surface observation system 60 and an autofocus system 70 as auxiliary components to the exposure operation.

[0036] The light source device 10 is an ultraviolet (UV) illumination source, where UV refers to wavelengths of 10–400 nm, but practically, wavelengths of 300–400 nm are used. The light source device 10 includes a pulsed laser 11, a laser output stabilization device 12, a λ / 2 wavelength plate 13, a homogenizer 14, relay lenses 15a and 15b, and a laser controller 19. The pulsed laser 11 is a Q-switched pulsed YAG laser that outputs, for example, UV laser pulses with a wavelength of 355 nm based on an external trigger signal. The laser output stabilization device 12, which will be described in detail later, is used to control the energy value of the laser pulses output from the light source device 10. The λ / 2 wavelength plate 13 is configured to adjust the polarization direction of the laser beam output from the pulsed laser 11 via the laser output stabilization device 12. The homogenizer 14 homogenizes the laser beam in two dimensions, and the relay lenses 15a and 15b are used to guide the homogenized laser beam L11 to the optical modulation unit 20 at an appropriate size. The homogenizer 14 can employ a structure using a compound eye lens in two stages, but it can also use components such as optical tunnels. The laser controller 19 operates under the control of the control device 90 and the stage controller 49, and outputs a trigger signal to the pulsed laser 11 to control the timing of the output of ultraviolet laser pulses.

[0037] The optical modulation unit 20 includes two reflective liquid crystal modulation devices 21 and 22, a polarization beam splitter 23, lenses 24 and 25, and a modulation control device 29. The two reflective liquid crystal modulation devices 21 and 22 have identical structures. The first reflective liquid crystal modulation device 21, also called LCOS (liquid crystal on silicon), includes pixels arranged in a matrix to change their polarization state. The first reflective liquid crystal modulation device 21 spatially modulates the polarization state of the S-polarized component of the laser beam reflected by the polarization beam splitter 23. The second reflective liquid crystal modulation device 22, also called LCOS, includes pixels arranged in a matrix to change their polarization state. The second reflective liquid crystal modulation device 22 spatially modulates the polarization state of the P-polarized component of the laser beam transmitted through the polarization beam splitter 23. Here, the first reflective liquid crystal modulation device 21 and the second reflective liquid crystal modulation device 22 have approximately the same pixel arrangement pattern. Through the optical branching of the polarization beam splitter 23, laser beams with different polarization states are incident on the first reflective liquid crystal modulation device 21 and the second reflective liquid crystal modulation device 22. Lenses 24 and 25 function to make the principal rays of the laser beam illuminating the reflective liquid crystal modulation devices 21 and 22 parallel beams. Lenses 24 and 25 function as part of the projection optics system 30 in the sense of projecting the pattern surfaces 21p and 22p of the reflective liquid crystal modulation devices 21 and 22 onto the surface of the workpiece WO. The pattern light L12, as the P-polarized component modulated by the first reflective liquid crystal modulation device 21, is passed through the polarization beam splitter 23, thereby being transformed to reflect information about the brightness pattern, and then incident on the objective lens 31. The pattern light L12, as the S-polarized component modulated by the second reflective liquid crystal modulation device 22, is reflected by the polarization beam splitter 23, thereby being transformed to reflect information about the brightness pattern, and then incident on the objective lens 31. The modulation control device 29 operates under the control of the control device 90, controlling the rotation of the pattern or polarization angle to be formed by the reflective liquid crystal modulation devices 21 and 22 in pixels.

[0038] Figure 2This is a cross-sectional view illustrating an example of the structure of the first reflective liquid crystal modulation apparatus 21. The first reflective liquid crystal modulation apparatus 21 has a structure in which a liquid crystal layer 21c is sandwiched between a light-transmitting substrate 21a and a circuit functional layer 21b. A transparent electrode 21t is formed on the surface of the light-transmitting substrate 21a. The circuit functional layer 21b on the Si substrate 21e includes a circuit layer 21g, a light-shielding layer 21h, and a reflective pixel electrode layer 21i. An alignment film 21j is formed on the surface of the transparent electrode 21t covering the light-transmitting substrate 21a, and an alignment film 21k and a dielectric multilayer film 21u are formed on the surface of the reflective pixel electrode layer 21i on the side of the liquid crystal layer 21c. The first reflective liquid crystal modulation device 21 is designed for use in the ultraviolet wavelength region. The light-transmitting substrate 21a is made of synthetic quartz, the liquid crystal layer 21c has minimal absorption in the ultraviolet region (especially in wavelengths longer than 300 nm), the alignment films 21j and 21k are made of SiO2, and the reflective pixel electrode layer 21i is formed of a dielectric multilayer film. The first reflective liquid crystal modulation device 21 has a structure capable of withstanding long-term use in the ultraviolet region. Although not shown in the figure, the second reflective liquid crystal modulation device 22 also has the same structure as the first reflective liquid crystal modulation device 21 and can withstand long-term use in the ultraviolet region. The first reflective liquid crystal modulation device 21 and the second reflective liquid crystal modulation device 22 have the following characteristics: compared to digital micromirror devices, even with increased grayscale, the display time remains almost unchanged. Specifically, approximately 1000 grayscale levels can be achieved with 10 bits of information, and the light intensity of the target can be achieved simply by irradiating a laser beam L11 with target energy in a pulsed manner. Furthermore, in the case of digital micromirror devices, which require time-modulated grayscale representation, there is a problem that the more grayscale is increased, the longer the exposure time becomes.

[0039] Return to Figure 1 In the projection optical system 30, the objective lens 31 cooperates with the lenses 24 and 25 of the light modulation unit 20 to project the patterned light modulated by the light modulation unit 20 onto the surface of the workpiece WO, which is supported on the object stage 40, specifically onto the resist film. The objective lens 31 can achieve high resolution even under ultraviolet light. For the resist film, if light with the required energy is applied, a chemical reaction does not occur instantaneously, but rather photosensitization occurs gradually. There is no particular limitation on the projection magnification of the projection optical system 30; for example, it can perform 1x projection or 1 / 16x projection. Specifically, the objective lens 31 is a 1 / 16x reduced projection type, for example, with an NA of approximately 0.75. In the case of 1 / 16x projection, the pixel or pixel size of the reflective liquid crystal modulation devices 21 and 22 is set to 8 μm, and the pixel size on the surface of the workpiece WO becomes 0.5 μm.

[0040] The worktable 40 can support the workpiece WO and move it in the XY directions, and can rotate about the X, Y, and Z axes. The worktable 40 is controlled by the worktable controller 49. Under the control of the control device 90, the workpiece WO can be precisely moved to a predetermined position and can move along a specified path at a desired speed. The workpiece WO is, for example, an exposure mask, but it can also be a semiconductor wafer, etc.

[0041] The lens stage 50 allows the objective lens 31 to move up and down in the Z direction. The lens stage 50 is controlled by the stage controller 49. Under the control of the control device 90, the objective lens 31 can be slightly moved in the Z direction to adjust the focusing state of the pattern projected onto the workpiece WO.

[0042] The surface observation system 60 includes a surface observation light source 61, a polarizing plate 62, a dichroic semi-reflective mirror prism 63, a lens 64, a polarizing plate 65, a λ / 4 plate 66, and a CCD camera 67. The surface observation system 60 is fixed relative to the light modulation unit 20.

[0043] Figure 3The surface observation system 60 is shown here. The surface observation light source 61 is made of, for example, an LED, and emits long-wavelength illumination light (e.g., visible light such as red light with a wavelength of 567 nm) L21 that is substantially non-photosensitive to the resist formed on the surface of the workpiece WO on the worktable 40. The polarizer 62 cuts off the S-polarization and selectively directs the P-polarization onto the dichroic semi-reflective mirror prism 63. The dichroic semi-reflective mirror prism 63 selectively reflects the illumination light L21 and directs the P-polarized illumination light L21 onto the first reflective liquid crystal modulation device 21 via the polarizing beam splitter 23 and the lens 24. The reflected light from the first reflective liquid crystal modulation device 21 includes both P and S components. The polarizing beam splitter 23 branches the polarization of the laser beam L11 in the ultraviolet region but does not branch the polarization of the long-wavelength illumination light L21. The reflected light from the first reflective liquid crystal modulation device 21, as modulated light, passes at least partially through the polarizing beam splitter 23. The reflected light from the first reflective liquid crystal modulation device 21 is further partially passed through the dichroic semi-reflective mirror prism 63, through the λ / 4 plate 66, and incident on the objective lens 31 in a mixed state of right-handed and left-handed circular polarization, illuminating the workpiece WO on the object stage 40. The image light L22 from the workpiece WO becomes a mixed state of P-polarization and S-polarization after passing through the λ / 4 plate 66, is partially reflected by the dichroic semi-reflective mirror prism 63, passes through the lens 64, etc., and is incident on the CCD camera 67 after passing through the polarizing plate 65. Regarding the illumination light L21, the pattern or image formed by the first reflective liquid crystal modulation device 21 is also projected onto the surface of the workpiece WO through the lens 24 and the objective lens 31, and the surface image of the workpiece WO is formed on the image sensor of the CCD camera 67 through the objective lens 31 and the lens 64. The polarizing plate 65 prevents the P-polarized illumination light L21 from the surface observation light source 61 from directly incident on the CCD camera 67. By using the surface observation system 60, the pattern formed by the first reflective liquid crystal modulation device 21 and the substrate pattern formed on the substrate of the workpiece WO can be observed over time. By analyzing the observation results and operating the stage controller 49 by the control device 90, the worktable 40 can be moved appropriately relative to the light modulation unit 20 and the projection optical system 30, and the pattern or exposure image formed by the first reflective liquid crystal modulation device 21 can be formed at an appropriate position on the workpiece WO.

[0044] The surface observation system 60 can observe not only the pattern of the first reflective liquid crystal modulation device 21, but also the pattern of the second reflective liquid crystal modulation device 22.

[0045] Return to Figure 1The autofocus system 70 includes an AF light source 71, a polarizer 72, a striped pattern mask 73, a polarizing beam splitter 74, semi-reflective mirror prisms 75 and 76, a first image sensor 77a, a second image sensor 77b, and an AF control circuit 79. The autofocus system 70 shares the lens 64 and the dichroic semi-reflective mirror prism 63 that constitute the surface observation system 60.

[0046] Figure 4The autofocus system 70 is shown here. The AF light source 71 is, for example, an LED, which emits long-wavelength illumination light (e.g., visible light such as red light with a wavelength of 567 nm) L31 that is substantially non-photosensitive to the resist formed on the surface of the workpiece WO. In this embodiment, the wavelength of the illumination light L31 is made to match the wavelength of the illumination light L21 of the surface observation system 60. The polarizer 72 cuts off the S-polarization, allowing the P-polarization to selectively enter the stripe pattern mask 73 and the polarizing beam splitter 74. The stripe pattern mask 73 is used to project a stripe pattern onto the surface of the workpiece WO during focusing. The polarizing beam splitter 74 allows the illumination light L31 that has passed through the stripe pattern mask 73 to be transmitted as is, and the semi-reflective mirror prism 75 reflects the P-polarized illumination light L31, causing it to enter the λ / 4 plate 66 via the lens 64 and the dichroic semi-reflective mirror prism 63. The circularly polarized illumination light L31, passing through the λ / 4 plate 66, is incident on the objective lens 31, illuminating the workpiece WO on the worktable 40. The circularly polarized image light L32 from the workpiece WO, passing through the λ / 4 plate 66, becomes S-polarized and is partially reflected by the dichroic semi-reflective prism 63. After passing through the lens 64, the light path is bent by the semi-reflective prism 75 and incident on the polarization beam splitter 74. The image light L32, reflected by the polarization beam splitter 74 and becoming non-returning to the AF light source 71, is branched by the semi-reflective prism 76 and incident on the first image sensor 77a and the second image sensor 77b. In summary, the illumination light L31 projects the stripe pattern of the stripe pattern mask 73 onto the surface of the workpiece WO through the lens 64 and objective lens 31, and projects the stripe pattern on the workpiece WO onto the image sensors 77a and 77b through the objective lens 31 and lens 64. Image sensors 77a and 77b are controlled by an AF control circuit 79. The AF control circuit 79 can determine whether the objective lens 31 is in focus, front focus, or back focus state based on the contrast of the images detected by the image sensors 77a and 77b, and can output this focus or defocus state to the control device 90. Furthermore, the first image sensor 77a is positioned forward relative to the focus state, and the second image sensor 77b is positioned rearward relative to the focus state. Therefore, by using the lens stage 50 to move the objective lens 31 vertically in the Z direction, and stopping the movement of the objective lens 31 at a position where the contrast of the pattern detected by the first image sensor 77a and the contrast of the pattern detected by the second image sensor 77b are the same, a focus state can be achieved.

[0047] To avoid interference, when the autofocus system 70 is operating, the surface observation light source 61 of the surface observation system 60 is stopped, and when the surface observation system 60 is operating, the AF light source 71 of the autofocus system 70 is stopped. Furthermore, in the exposure described later, the light source 61 of the surface observation system 60 is turned off to stop the surface observation function, while the light source 71 of the autofocus system 70 is turned on to enable the autofocus function to operate in real time.

[0048] Figure 5 This is an explanation of the compilation. Figure 1 This diagram illustrates an example of the construction of the laser output stabilization device 12 in the light source device 10. The laser output stabilization device 12 comprises a beam splitter 12a, a first photodiode 12b, an optical delay circuit 12c, an optical switch 12d, a beam splitter 12e, and a second photodiode 12f, forming an optical system. The laser output stabilization device 12 also comprises an integrator 12h, a comparator 12i, and a switch driver 12j, forming a circuit system. In the laser output stabilization device 12, the first photodiode 12b can detect changes in the output energy of the pulsed laser 11 at ultra-high speed. The optical delay circuit 12c comprises mirrors 12p and 12q, and a prism mirror 12r, which can compensate for processing delays in the circuit system. The optical delay circuit 12c can also move the prism mirror 12r along the Dj direction, thereby extending the optical path length toward the optical switch 12d and shortening the optical path length. The optical switch 12d includes a Pockels cell 12s and a polarization beam splitter 12t, capable of cutting off the laser beam L11 emitted by switching the polarization direction driven by the switch driver 12j. The second photodiode 12b is a sensor used to determine whether the energy of the laser beam L11 output from the laser output stabilization device 12 has changed to the target value. Furthermore, the Pockels cell 12s also operates in ultraviolet light with a wavelength of approximately 300 nm. In addition, the rise time is approximately 0.5 ns or less, enabling high-speed switching processing.

[0049] Figure 6A This diagram illustrates the operation of the laser output stabilization device 12, showing the input laser waveform W1 detected by the first photodiode 12b and the integrated waveform W2 corresponding to the output of the integrator 12h. The emission of the input laser waveform W1 may not be stable each time; if it emits light multiple times, the emission intensity tends to deviate. The comparator 12i determines whether the energy value of the integrated waveform W2 reaches a predetermined threshold TH. If the integrated waveform W2 reaches the predetermined threshold TH, the switch driver 12j switches the Pockels cell 12s from off to on, cutting off the laser beam L11. Figure 6BThe waveform of the laser beam L11 output from the laser output stabilization device 12 is shown. The output laser waveform W3 of the laser beam L11 almost returns to zero when the energy value of the integral waveform W2 reaches a predetermined threshold TH. As a result, the energy of the laser beam L11 output from the light source device 10 can be precisely maintained at the target value and thus stabilized.

[0050] Reference Figure 7 The exposure operation of the exposure apparatus 100 is explained. An exposure area AR is set on the photomask serving as the workpiece WO, and this exposure area AR combines multiple partial areas RE arranged in a matrix. Although a 6×4 partial area RE is set, the setting of the partial area RE can be appropriately changed according to the size of the workpiece WO and the exposure accuracy. In the illustrated example, for example, the pixels of the first reflective liquid crystal modulation device 21 have a size of 0.5μm×0.5μm, and the partial areas RE have 1920 pixels horizontally and 1200 pixels vertically, with a size of 0.6mm×0.96mm. Using the object stage 40, the workpiece WO is moved back and forth at equal intervals as shown by the trajectory TR. At this time, an intermittent scanning exposure is performed. In a specific embodiment, the horizontal width of the partial areas RE in the Y direction is 0.96mm, and the interval of the trajectory TR is also 0.96mm. Furthermore, when the workpiece WO is scanned using the object stage 40 and lens exposure is performed synchronously with this scanning movement, light emission and exposure are performed using the pulse pattern PP shown on the left side of the figure. The exposure time te, which is the pulse width, can be in the nanosecond range, and the exposure interval ti is, for example, 50 ms. During the exposure interval ti, the patterns of the first reflective liquid crystal modulation device 21 and the second reflective liquid crystal modulation device 22 are rewritten. In the case of the embodiment, since the longitudinal width of a portion of the region RE is moved by 0.6 mm with an exposure interval ti = 50 ms, the moving speed of the worktable 40 is 12 mm / s. Under such a moving speed of the worktable 40, the nanosecond-level exposure time te is an extremely short time, which is equivalent to the workpiece WO being substantially stationary. That is, the exposure light can be generated within the time width during which the worktable 40 is regarded as substantially stationary, and no image deviation occurs on the workpiece WO during exposure. Moreover, the rewriting or switching of the first reflective liquid crystal modulation device 21 can be performed during the relative movement of the workpiece WO, and the low speed of the switching of the first reflective liquid crystal modulation device 21 can be compensated by the pulse exposure of the beam.

[0051] Reference Figures 8A-8F To explain the exposure modes. Figure 8A and 8BThis diagram illustrates the operation in "1×" mode. In this case, only one of the reflective liquid crystal modulation devices 21 and 22 is operated, and the pixels PX are arranged in a matrix to form a patterned area PA. A beam point BS0 corresponding to the pixels PX is formed on the projection side. The beam center BC is shown in the center of the beam point BS0 for easy viewing. In "1×" mode, exposure can be performed at a resolution approximately equal to the resolution obtained by reducing the resolution of the pixels PX of the reflective liquid crystal modulation device 21 through the objective lens 31. Figure 8C and 8D This diagram illustrates the operation in "2×" mode. In this case, the first reflective liquid crystal modulation device 21 and the second reflective liquid crystal modulation device 22 are operated, but the pattern area PA11 of the first reflective liquid crystal modulation device 21 and the pattern area PA21 of the second reflective liquid crystal modulation device 22 are offset by half a pixel in the -Y direction. Furthermore, double exposure is performed by offsetting the exposure of the first reflective liquid crystal modulation device 21 and the second reflective liquid crystal modulation device 22 by half a pixel in the X direction, thereby exposing the pattern areas PA12 and PA22 as well. Observing the arrangement of the beam point BS and beam center BC formed by these pattern areas PA11, PA21, PA12, and PA22, it can be seen that exposure is performed using a grid pattern MP that is reduced to 1 / 2 in both directions. Through the above exposure in "2×" mode, the edges of the transferred pattern can be smoothed, improving the fineness. Figure 8E and 8F This diagram illustrates the operation in "4×" mode. In this case, the pattern region PA11 of the first reflective liquid crystal modulation device 21 and the pattern region PA21 of the second reflective liquid crystal modulation device 22 are configured to be offset by 1 / 4 pixel in the -Y direction and by half a pixel in the -X direction. Furthermore, by performing double exposure with the exposures of the first reflective liquid crystal modulation device 21 and the second reflective liquid crystal modulation device 22 offset by 1 / 4 pixel in the X direction and by half a pixel in the -Y direction, exposure is also performed by the pattern regions PA12 and PA22. Observing the arrangement of the beam point BS and beam center BC formed by these pattern regions PA11, PA21, PA12, and PA22, it can be seen that an exposure approximating a grid pattern MP reduced to 1 / 4 in both length and width is performed. Furthermore, Figures 8A-8F The exposure modes shown are just examples; of course, various exposures with multiple settings can be performed with different configurations.

[0052] Figure 9The diagram shows the beam profile of the exposure light in pixel-by-pixel of the pattern light L12 projected onto the workpiece WO, illustrating exposure at gray levels. In the diagram, the horizontal axis indicates the position on the workpiece WO, and the vertical axis indicates the light intensity projected onto the workpiece WO. Using the light source device 10 described above, a laser beam L11 with a stable energy value can be generated, and as a feature of the reflective liquid crystal modulation devices 21 and 22, it has the characteristic of being able to pulse-expose a pattern of 1000 gray levels. Therefore, it can be seen that by setting the photosensitive threshold of the resist to RT, and by adjusting various beams BF1 to BF3 of different gray levels, the linewidth of the resist can be adjusted within the range of LW1 to LW3. Such gray-level exposure, for example, can be achieved... Figures 8A-8F The various exposure modes shown are utilized.

[0053] As explained above, the exposure apparatus 100 of the above embodiment illuminates the reflective liquid crystal modulation devices 21 and 22 with a pulsed laser beam L11. The object, i.e., the workpiece WO, on the target stage 40 is exposed using the pattern light L12 modulated by the reflective liquid crystal modulation devices 21 and 22 and imaged by the projection optical system 30. Therefore, it is possible to maintain the exposure throughput while achieving high precision in adjusting the illumination of the reflective liquid crystal modulation devices 21 and 22. Furthermore, when changing the exposure area while moving the workpiece support portion of the target stage 40, from the viewpoint of moving the workpiece support portion of the target stage 40 with high precision, there is a certain limit to the moving speed. It is easy to rewrite the pattern of each frame of the reflective liquid crystal modulation devices 21 and 22 at a speed corresponding to this speed limit.

[0054] This invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit. For example, in the light modulation unit 20, three or more reflective liquid crystal modulation devices can be combined to synthesize an exposure pattern. Conversely, the light modulation unit 20 can be configured such that it does not require the use of two reflective liquid crystal modulation devices 21 and 22, and exposure is performed using only a single reflective liquid crystal modulation device 21. However, when exposure is performed using only the reflective liquid crystal modulation device 21, it is preferable to improve light utilization efficiency by converting all the pulsed lasers 11 generated in the light source device 10 to S-polarization. Even when exposure is performed using only a single reflective liquid crystal modulation device 21, by repeating... Figure 7 The exposure in the trajectory TR shown is also related to Figure 8B Similarly, as shown, overlapping exposure or overlapping exposure can be performed with a specified offset below the pixel pitch.

[0055] The structures illustrated for the surface observation system 60 and the autofocus system 70 are merely examples, and various methods can be used to properly align the object with the stage 40 and the projection optical system 30 relative to the light modulation unit 20.

[0056] Multiple light modulation units 20 and projection optical systems 30 can also be arranged and combined to form a device for large-area exposure.

Claims

1. An exposure apparatus, wherein, have: Reflective liquid crystal modulation device; The light source device illuminates the reflective liquid crystal modulation device in the same way with pulsed laser light in the homogenized ultraviolet wavelength region; A projection optical system is used to image the reflected light modulated by the reflective liquid crystal modulation device; and A worktable supports an object that is exposed using a pattern imaged by the projection optical system. While moving the object via the worktable, the grid-like areas on the object are exposed sequentially at predetermined periodic intervals, while the entire object is exposed. During the exposure intervals, the pattern of the reflective liquid crystal modulation device is rewritten. The light source device includes a pulsed laser that generates exposure light for specific regions with a pulse width that is considered to be substantially stopped by the stage.

2. The exposure apparatus according to claim 1, wherein Overlapping exposures are performed with a specified offset below the pixel pitch.

3. The exposure apparatus according to claim 1, wherein have: Two reflective liquid crystal modulation devices; and The beam splitter branches the laser light from the light source device and distributes it to the two reflective liquid crystal modulation devices according to the polarization state. The beam splitter synthesizes the reflected light modulated by the two reflective liquid crystal modulation devices.

4. The exposure apparatus according to claim 3, wherein The beam splitter is a polarization beam splitter, which allows light with different polarization states to be incident on the two reflective liquid crystal modulation devices, and synthesizes reflected light with different polarization states modulated by the two reflective liquid crystal modulation devices.

5. The exposure apparatus according to claim 4, wherein The two reflective liquid crystal modulation devices have substantially the same pixel arrangement pattern and are configured to produce a predetermined offset in the image synthesized by the polarization beam splitter.

6. The exposure apparatus according to claim 5, wherein The specified offset is below the pixel spacing.

7. The exposure apparatus according to any one of claims 1 to 6, wherein The light source device monitors the energy of the pulsed laser source and the laser light from the pulsed laser source, and cuts off the output of the laser light when a predetermined threshold is reached.

8. The exposure apparatus according to claim 7, wherein The reflective liquid crystal modulation device adjusts the linewidth of the pattern to be exposed on the object by controlling the grayscale of the reflected light.

9. The exposure apparatus according to any one of claims 1 to 6, wherein, It has a surface observation system that monitors the alignment of the pattern with respect to an object on the worktable. The surface observation system can observe the pattern on the reflective liquid crystal modulation device and the pattern set on the object on the worktable in an overlapping manner.

10. The exposure apparatus according to any one of claims 1 to 6, wherein It has an autofocus system that monitors the imaging state relative to an object on the worktable.

Images