JP5973207B2 - Maskless exposure system - Google Patents

Description

  The present invention relates to a maskless exposure apparatus that forms a pattern using a light modulation element array, and more particularly to an exposure method of the maskless exposure apparatus.

  The maskless exposure apparatus usually includes a DMD (Digital Micro-mirror Device) in which micromirrors are two-dimensionally arranged, and pattern light is applied to the substrate by controlling each micromirror according to the pattern. Projected. As the projection area (exposure area) by the light modulation element array moves relative to the substrate, pattern light corresponding to the position of the exposure area is sequentially projected.

  The resolution of the pattern in the maskless exposure apparatus is determined by the mirror size, the magnification of the reduction projection optical system, the NA, and the like. As a method for improving the resolution, phase shift exposure is known in which a substrate is simultaneously irradiated with two beams whose phases are shifted by ½ wavelength (see Patent Document 1).

  There, two DMDs are arranged and each beam is irradiated. At this time, every other mirror of each DMD is ON / OFF controlled to irradiate adjacent pixels with different beams. Since the phase of the beam is shifted by a half wavelength between pixels, a portion between adjacent pixels becomes a dark portion due to light interference. As a result, the same resolution improvement as when the Levenson type phase shift mask is used in the mask exposure apparatus can be obtained.

  It is also possible to irradiate two beams having a phase difference of half wavelength by shifting the projection image of the first beam and the projection image of the second beam by half pixel pitch along both the vertical and horizontal directions. In this case, all mirrors of each DMD can be used.

JP 2009-71116 A

  The conventional phase shift exposure in which the phase shift mask is developed in a maskless exposure apparatus aims at improving the resolution in pixel units, and creates a portion where the exposure energy amount is close to 0 between adjacent pixels. The pattern resolution is improved by the dark part. However, in the case of a maskless exposure apparatus, miniaturization of the pattern width is not always the most important issue.

  For example, when a maskless exposure apparatus is used with a printed circuit board or the like as an object to be manufactured, exposure is often performed using an imaging lens having a magnification of about 1 × instead of reduced projection exposure that forms a pattern close to the exposure wavelength. . This is due to the fact that the resolution is limited to some extent by the micromirror size, and that the pattern width is sufficiently larger than the exposure wavelength for the purpose of drawing a large size substrate.

  On the other hand, the imaging lens incorporated in the maskless exposure apparatus has a relatively shallow depth of focus from the viewpoint of reliably satisfying the required resolution requirement. Therefore, if the focal position is slightly shifted, blurring is likely to occur, leading to a decrease in pattern resolution. In order to suppress the blur, it is necessary to improve the contrast of the pattern image.

  However, the conventional exposure method can increase the resolution in the situation where the image is formed within the focal position and depth of focus of the imaging lens, but the solution of the pattern when deviating from the focal depth of the imaging lens. This is not an exposure method that ensures image quality, that is, maintains a sufficient contrast.

  Therefore, it is required to perform exposure for realizing contrast improvement while using the light modulation element array.

  An exposure apparatus according to the present invention includes a light modulation element array in which a plurality of light modulation elements capable of switching the reflection direction of light according to a change in posture are two-dimensionally arranged, a coherent first light, and a first light. An illumination system that causes the second light having a phase difference and coherency to enter the light modulation element array along the first direction and the second direction, respectively, and the first and second light reflected by the light modulation element array An imaging optical system that forms an image of the second light on the pattern forming surface, and an exposure control unit that controls the posture of each of the plurality of light modulation elements according to the pattern data.

  Each of the plurality of light modulation elements reflects the first light in a direction along the optical axis of the imaging optical system, and reflects the second light in a direction along the optical axis of the imaging optical system. It is possible to take a posture at the second position. In other words, the light modulation element is configured to reflect the first and second lights to the imaging optical system when the plurality of light modulation elements can be positioned at the first position and the second position. The first and second light incident angles with respect to the array and the position of the imaging optical system are determined.

  When a DMD or the like is used as a light modulation element array, each light modulation element has a first position inclined by a predetermined angle from the flat state toward the incident direction of the first light, and an incident direction of the second light from the flat state. The posture can be changed between the second position inclined by a predetermined angle facing toward and a flat state. In particular, the ON state and the OFF state can be set to the first position and the second position (or vice versa).

  Various configurations can be applied to the lighting system. For example, the illumination system includes a first light source that irradiates the first light, a second light source that irradiates the second light, and a phase shift optical system that shifts the phase with respect to the first light or the second light. Should be provided.

  Alternatively, the illumination system shifts the phase with respect to the first light or the second light, the light source that emits the illumination light, the splitting optical system that divides the illumination light into the first light and the second light, and You may make it provide a phase shift optical system.

  In the present invention, the exposure control unit selectively positions the plurality of light modulation elements at either the first position or the second position according to the pattern. When the first light and the second light are projected onto the substrate as diffracted light, a dark portion stands out due to the light interference action based on the phase difference in a place where the intensity distribution of the first light and the intensity distribution of the second light overlap. A part arises. As a result, a sufficient luminance difference is secured at the pattern edge or the like.

  As described above, the exposure processing of the present invention selectively positions the light modulation element in accordance with pattern formation and causes interference exposure by diffracted light. A so-called Levenson type phase shift mask, halftone type phase shift The interference exposure for the purpose of improving the resolution (pattern width miniaturization) realized by a mask or the like is developed to interference exposure for increasing contrast. Since this interference exposure can freely set two light interference positions depending on the posture of each light modulation element, various interference exposures can be realized according to the pattern shape and type.

  As for the phase difference between the first light and the second light, the phase may be shifted within the range where the light intensity distributions overlap. Alternatively, the phase may be shifted so that the pattern boundary applies. For example, the first light and the second light can be coherent light having a phase difference of ½ wavelength.

  For example, when the pattern array is an array having a regular interval, the exposure control unit is a light modulation element that projects pattern light (guides light to the substrate surface) among a plurality of light modulation elements, and has a light intensity distribution. Can be positioned at the first position and the other light modulation element at the second position with respect to the light modulation elements that project light overlapping each other. Due to the interference action, a dark part is formed in a portion where diffracted lights having different phases overlap in an area to be non-exposed (hereinafter referred to as a non-exposure target area), thereby improving contrast.

  In particular, the exposure control unit is a light modulation element that projects light onto an exposure target area facing each other with the non-exposure target area sandwiched between the plurality of light modulation elements, and the light intensity distribution in the non-exposure target area Light projection elements projecting light overlapping each other, the light modulation element projecting light onto one exposure target area is the first position, and the light modulation element projecting light onto the other exposure target area is the second position. Can be positioned.

  When performing such interference exposure, the exposure control unit positions the light modulation element that projects the pattern light at the first position with respect to the first light incidence, and the second position with respect to the second light incidence. Can be positioned. Moreover, the exposure control part should just position the light modulation element which does not project pattern light in a flat state.

  On the other hand, the exposure control unit positions the light modulation element that projects the pattern light among the plurality of light modulation elements at one of the first position and the second position, and does not expose the light according to the non-exposure target area. It is possible to position the modulation element on the other side. In this case, the illumination system reduces the light intensity of one of the first light and the second light incident on the light modulation element corresponding to the non-exposure target area relative to the other light. (E.g., several percent light intensity with respect to the first light). Thereby, the non-exposure target area is not exposed, while the dark part becomes clear.

  For example, each light modulation element is inclined from the flat state by a predetermined angle toward the incident direction of the first light, and the second position is inclined by a predetermined angle from the flat state to the incident direction of the second light. The exposure control unit positions the light modulation element for projecting pattern light at one of the first position and the second position, and modulates light according to the non-exposure control area. What is necessary is just to position an element in the other position.

  An exposure head according to another aspect of the present invention includes a light modulation element array in which a plurality of light modulation elements capable of switching the reflection direction of light according to a change in posture are two-dimensionally arranged, first light having coherency, An illumination optical system for causing a second light having a phase difference with respect to the first light to be incident on the light modulation element array along the first direction and the second direction, respectively, and a light modulation element array An imaging optical system that forms an image of the reflected first and second light on the pattern forming surface, and each of the plurality of light modulation elements emits the first light in a direction along the optical axis of the imaging optical system. The first position to be reflected and the second position to reflect the second light in the direction along the optical axis of the imaging optical system can be set, and a plurality of light modulation elements can be arranged according to the pattern. To be selectively positioned in either the first position or the second position. And butterflies.

  According to the present invention, in a maskless exposure apparatus, a pattern image with contrast can be formed and blurring can be suppressed.

It is a schematic block diagram of an exposure apparatus. It is a schematic block diagram of an illumination system. It is a schematic block diagram inside an exposure head. It is the figure which showed the attitude | position state of the micromirror, and the reflection direction of light. It is the figure which showed the mirror image in DMD, and the kind of reflected light. It is the figure which showed the light intensity distribution in the exposure surface. It is a schematic block diagram of the illumination system in 2nd Embodiment. It is a schematic block diagram of the illumination system in 3rd Embodiment. It is a schematic block diagram inside the exposure head in 3rd Embodiment. It is the figure which showed the attitude | position of the micromirror in 3rd Embodiment, and the reflection direction of light.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic block diagram of an exposure apparatus according to the first embodiment.

  The exposure apparatus (drawing apparatus) 10 is a maskless exposure apparatus that forms a pattern by irradiating light onto a substrate S coated or pasted with a photosensitive material such as a photoresist. The system control circuit 19 controls the entire exposure operation.

  The exposure apparatus 10 includes an illumination system 20, a DMD 30, and an imaging optical system 40. The illumination system 20 includes two laser light sources and an illumination optical system (not shown here), and irradiates the DMD 30 with illumination light. The illumination system 20, DMD 30, and imaging optical system 40 constitute a so-called exposure head. The light source driving unit 15 drives each laser light source.

  When CAD / CAM data composed of vector data or the like is input to the exposure apparatus 10, it is sent to the raster conversion and exposure data conversion circuit 16. The raster conversion / exposure data conversion circuit 16 converts the vector data into raster data, and generates exposure data for interference exposure described later based on the generated raster data. The generated exposure data is temporarily stored in the buffer memory 17 and then sent to the DMD driving circuit 18.

  The DMD 30 is a light modulation element array (light modulator) in which minute micromirrors are two-dimensionally arranged, and each micromirror selectively switches the light reflection direction by changing the posture. The attitude of each mirror is controlled by the DMD driving circuit 18 so that light corresponding to the pattern enters the imaging optical system 40. The imaging optical system 40 forms an image of the incident light on the surface of the substrate S, thereby projecting pattern light.

  The drawing table 11 can be moved along the X and Y directions by the stage driving unit 13. The stage drive unit 13 moves the drawing table 11 in accordance with a control signal from the stage control circuit 14. The position detection sensor 12 detects the position of the drawing table 11, that is, the position of the substrate S.

  During exposure, the drawing table 11 moves at a constant speed along the scanning direction. A projection area (hereinafter referred to as an exposure area) by the entire DMD 30 relatively moves on the substrate as the substrate S moves. Exposure data is sequentially input to the buffer memory 17, and data is sent from the buffer memory 17 to the DMD driving circuit 18 in accordance with the relative position of the detected exposure area.

  The exposure operation is performed according to a predetermined exposure pitch, and is controlled so that the micromirror projects pattern light in accordance with the exposure period. By adjusting the control timing of each micro mirror of the DMD 30 according to the relative position of the exposure area, the light of the pattern to be drawn is sequentially projected at the position of the exposure area. By scanning the entire substrate S, a pattern is formed on the entire substrate S.

  As an exposure method, not only a continuous movement method that moves at a constant speed, but also step and repeat movements that move intermittently are possible. Also, multiple exposure (overlap exposure) in which the projection area at the time of exposure shot is partially overlapped is possible. Although an exposure apparatus provided with one exposure head has been described here, drawing processing can also be performed using a plurality of exposure heads.

  FIG. 2 is a schematic configuration diagram of the illumination system. FIG. 3 is a schematic block diagram of the inside of the exposure head. It is the figure which showed the attitude | position state of the micromirror, and the reflection direction of light. FIG. 4 is a diagram showing the posture state of the micromirror and the light reflection direction. The configuration of the illumination system 20 and the light modulation by each micromirror of the DMD 30 will be described with reference to FIGS.

  The illumination system 20 constituting the exposure head 100 includes first and second laser light sources 21A and 21B, both of which are laser oscillators, and each laser light source emits coherent light. At this stage, there is virtually no phase difference between the two beams.

  The first light emitted from the first laser light source 21A passes through the illumination optical system 22A and enters the DMD 30 via the mirror 24A. On the other hand, the second light emitted from the second laser light source 21B enters the phase plate 23 after passing through the illumination optical system 22B. The phase plate 23 is a wavelength plate that shifts the phase of the light by a half wavelength by providing an optical path difference, and the second light becomes a light that is shifted by a half wavelength phase with respect to the first light. It is incident on 24B. The second light incident on the mirror 24B is guided to the DMD 30.

  The optical axes E1 and E2 of the first light and the second light coincide with each other in the traveling direction of the mirrors 24A and 24B, and the mirrors 24A and 24B have the same inclination with respect to the optical axes E1 and E2. It is arranged in a state where it is inclined by an angle. The mirrors 24 </ b> A and 24 </ b> B cause the first light and the second light to enter (with absolute values) at the same incident angle with respect to the vertical direction V of the DMD 30.

  FIG. 4 shows the posture change of one micromirror M in the DMD 30. However, the micromirror M is exaggerated and drawn greatly. The micromirror M can be rotated about the central axis by an electrostatic field effect, and can be positioned in any one of three postures. The same applies to the other micromirrors.

  When the micro mirror M is in the ON state, the micro mirror M is tilted by 12 ° so as to face the incident direction of the first light from a flat state (0 degree) without tilt. On the other hand, when the micromirror M is in the OFF state, it is inclined at the same angle (−12 °) on the opposite side so as to face the incident direction of the second light. Further, the micromirror M can be positioned in a flat state (0 °) in addition to the ON / OFF state posture.

  The optical axis E3 of the imaging optical system 40 coincides with the surface vertical direction V of the DMD 30. The first light and the second light travel to the DMD 30 from a direction symmetric with respect to the DMD surface vertical direction V, that is, the optical axis E3. Both inclination angles with respect to the vertical direction V are equal in absolute value θ (= 24 °).

  When the micromirror M is in the ON state, the first light is reflected in the direction of the optical axis E3. When the micromirror M is in the OFF state, the second light is reflected in the direction of the optical axis E3. Accordingly, the first light is incident when the micromirror M is in the ON state, and the second light is incident when the micromirror M is in the OFF state. An image is formed on the surface of the substrate S by the system 40.

  On the other hand, when the micromirror M is in the ON state (12 °), the second light is incident on the micromirror M, and when the micromirror M is in the OFF state (−12 °), the first light is incident on the micromirror M. The first and second lights travel in directions (48 °, −48 °) deviating from the optical axis E of the image optical system 40.

  Further, when the micromirror M is positioned in a flat state, the micromirror M reflects the first light and the second light toward the traveling direction of the second light and the first light, respectively. Therefore, in the flat state, both the first light and the second light are guided out of the substrate. Even in the case where the micromirror M cannot be strictly positioned in the flat state, it is only necessary to be able to position in the flat state because of the purpose of light removal. The above-described micromirror ON / OFF and the progress of light in the flat state are the same for the other micromirrors.

  In the present embodiment, unlike the ordinary micromirror light modulation method, the micromirrors M are not turned on when the pattern is formed, and are switched off when the pattern is not formed. Select either OFF state or flat state.

  Specifically, when contributing to pattern formation, each micromirror M is switched to either the ON / OFF position. As a result, one of the first light and the second light is selected and projected onto the substrate S. At this time, the light that has not been selected is not affected because it is guided out of the substrate. On the other hand, the micromirror M corresponding to the region where the pattern light is not irradiated (exposure is OFF) is in a flat state because both the first light and the second light are discarded.

  As a result, the pattern light projected onto the entire exposure area is constituted by a light beam including both the first light and the second light, and light having a phase difference, that is, light having opposite phases. Interference exposure that interferes with each other is performed. This interference exposure is performed for each exposure operation. Although the case of positive exposure has been described here, in the case of negative exposure, the pattern forming portion of the micromirror is reversed, so that the ON / OFF state of the DMD is appropriately selected in consideration of interference of light reaching the substrate S.

  Whether each micromirror selects the first light or the second light depends on the pattern shape or the like formed at that time. Here, the phase difference is given to the light which forms the adjacent pattern edge part, and interference exposure is carried out. Hereinafter, interference exposure will be described.

  FIG. 5 is a diagram showing types of mirror images and reflected light in DMD. FIG. 6 is a diagram showing the light intensity distribution on the exposure surface.

  FIG. 5 shows modulation states of three micromirrors MPA1, MPA2, and MPA3 adjacent to each other. Projection areas (hereinafter referred to as “micro-exposure areas”) PA1, PA2, and PA3 (see FIG. 3) of the micromirrors MPA1, MPA2, and MPA3 are moved relative to each other on the substrate, and light is projected depending on the pattern to be formed at the position during the exposure operation. Is projected onto the substrate or led out of the substrate.

  As shown in FIG. 3, a case is considered in which a pattern that repeats a linear pattern is formed with a non-exposure target area (area that does not project pattern light) having a size of one minute exposure area width in between. FIG. 3 shows only the optical axes of the first light and the second light, and the individual light reflected by each micromirror is not shown. In an exposure operation, the light incident on the micromirrors MPA1, MPA2, and MPA3 is modulated so as to be projected, discarded, and projected, respectively. That is, the micromirrors MPA1 and MPA3 are positioned in a posture (ON state or OFF state) for projecting light onto the substrate, and the micromirror MPA2 is positioned in a posture (flat state) for guiding light out of the substrate. Here, guiding light out of the substrate means that light is not incident on the imaging optical system 40 and is guided to a light absorbing means (not shown).

  Here, the micromirror MPA1 reflects the first light, and the micromirror MPA3 reflects the second light. Therefore, the micromirror MPA1 is positioned in the ON state and the micromirror MPA3 is positioned in the OFF state. The micromirror that projects light inside the pattern may be projected with the same phase of light (first or second light). The intensities of the first light and the second light applied to the micromirrors MPA1 and MPA3 are expressed as opposite to each other because of a phase difference (see FIG. 5).

  FIG. 6 shows the phase of light, the intensity distribution, and the light intensity distribution after interference in interference exposure and non-interference exposure. The intensity distributions of the first light and the second light that actually reach the substrate include a diffracted light, so that the intensity distribution becomes a gentle mountain curve and extends to the adjacent minute exposure area PA2. Therefore, in the light intensity distribution L on the substrate, the first light and the second light interfere with each other in the minute exposure area PA2, and a portion near the light intensity 0 is generated.

  Comparing the light intensity distribution L0 of non-interference exposure and the light intensity distribution L of interference exposure, the light intensity distribution L0 is positive in both phase and intensity in the microexposure area PA2. The intensity of the valley of the intensity distribution produced by the light increases. Therefore, the light intensity distribution does not drop to near 0 in the fine exposure area PA2, and the intensity difference (luminance difference) between the fine exposure areas PA1 and PA2 is small.

  On the other hand, in the light intensity distribution L appearing by the interference exposure, there is a portion near the intensity 0 in the microexposure area PA2, so that the intensity difference between the microexposure areas PA1 and PA2 becomes large and the light intensity distribution becomes steep. The contrast increases.

  In this way, when two light beams having different phases are separated from each other by one microexposure area and imaged, interference of diffracted light occurs in the non-projection microexposure area PA2 sandwiched therebetween, and adjacent microexposure areas A light intensity distribution L having a large luminance difference is generated.

  In general, in order to form a pattern on the photosensitive surface of a substrate, the light intensity is determined so that the exposure energy amount RL (hereinafter referred to as the appropriate exposure amount RL) is greater than the sensitivity of the photosensitive material, and the pattern light is projected. There is a need. However, when the focal depth of the imaging optical system 40 deviates due to deformation or distortion of the substrate, the light intensity distribution L becomes a gentler curve distribution. Therefore, the difference between the maximum intensity portion or the minimum intensity portion and the appropriate exposure amount RL becomes small.

  In the case of non-interference exposure, the difference between the light intensity in the microexposure area PA2 and the appropriate exposure amount RL is not originally large, and therefore, when deviating from the focal depth, the pattern of the microexposure area PA1 and the microexposure area PA3 is seamless. There is a possibility that pattern edges are not formed.

  On the other hand, in the case of interference exposure, since the contrast between the projected portion and the non-projected portion is large and the range close to the intensity 0 is clear even when the imaging position is out of the range of the depth of focus, the range close to zero is clear. The patterns of the exposure area PA1 and the minute exposure area PA3 are separated. Therefore, the pattern edge is firmly formed, and the influence of blur does not appear in the pattern image.

  For pattern light that does not require interference, the raster data may be set to ON data so that the first light is emitted. In addition, raster data is set so that the micromirror is in a flat state for the exposure OFF area. It is also possible to set raster data by reversing the first light and the second light.

  As described above, according to the present embodiment, the first and second lights having a phase difference of half a wavelength and coherent are made incident on the DMD 30. When each micromirror of the DMD 30 forms a pattern, in each exposure operation, the micromirror that projects the first light is turned on (first position), and the micromirror that projects the second light is turned off (first). By switching to the second position, the first light or the second light is projected onto the substrate in units of minute exposure areas. On the other hand, in the case of an area where exposure is turned off (off), the micromirror is positioned in a flat state.

  By irradiating two differently phased lights to one DMD from different directions and controlling each micromirror of the DMD in three positions, the pattern light consisting of the two lights is projected onto the exposure area. The Then, interference exposure is performed in the non-exposure target areas of adjacent patterns across the minute exposure area width. As a result, the contrast of the pattern image is improved.

  By performing such interference exposure, a blur-free pattern can be formed even when a focus shift occurs due to unevenness or twist of the substrate. In particular, in the case of a large substrate used in a maskless exposure apparatus, minute irregularities and twists on the substrate surface are present in the manufacturing process, and an imaging optical system with a shallow depth of focus is often used. It is possible to form a pattern without incurring a decrease in the thickness.

  Further, the posture of each micromirror is not determined in advance, but is selectively determined according to the pattern. For this reason, it is possible to realize interference exposure only by extracting a pattern edge portion that needs to be enlarged in contrast with various pattern shapes and converting raster data of the portion into interference exposure data. In particular, since interference exposure is realized while using a single DMD, various exposures using phase shift and interference can be realized with a simple configuration.

  Note that the interference exposure of the present embodiment enables the first light and the second light to be projected so as to increase the light intensity difference between adjacent pixels such as the pattern edge portion, but the phase difference corresponding to a half wavelength is not present. The light intensity distribution can also be made steep by irradiating the pattern with light having extremely low light intensity.

  In this case, all the pattern lights are configured by the first light (or the second light), and the corresponding micromirrors are positioned in the ON state. On the other hand, the second light (or the first light) has a half-wavelength phase difference and is irradiated from the light source unit with a very small light intensity (for example, a light intensity of several percent of the first light). Let

  Then, the micromirror corresponding to the exposure OFF is positioned in the OFF state so as to project the second light onto the substrate. As a result, a valley is generated around the pattern of the first light due to the interference of the first light and the second light, and a steep light intensity distribution can be generated. Since the light intensity of the second light is sufficiently small, no pattern is formed in the exposure OFF portion.

  About the phase difference of 1st light and 2nd light, it is not limited to giving the phase difference for a half wavelength correctly. According to the distribution width of the light intensity distribution curve, a phase difference may be provided so that light interference (overlap between peaks and valleys) occurs.

  Next, an exposure apparatus according to the second embodiment will be described with reference to FIG. In the second embodiment, two lights are generated from one light source and are incident on the DMD. About another structure, it is substantially the same as 1st Embodiment.

  FIG. 7 is a configuration diagram illustrating an illumination system according to the second embodiment.

  The light source 121 of the illumination system 120 is configured by a laser oscillator, an LD, a discharge lamp, or the like, and emits coherent light. The light emitted from the light source 121 is split by a light splitting optical system 127 such as a beam splitter. Two beams (hereinafter referred to as first light and second light) obtained by the splitting are emitted from the light splitting optical system 127 in opposite directions.

  The first light enters the illumination optical system 122A via the mirrors 125A and 126A, is reflected by the mirror 124A, and then enters the DMD 30. On the other hand, the second light enters the illumination optical system 122B via the mirrors 125B and 126B and the phase shift plate 123, is reflected by the mirror 124B, and then enters the DMD 30.

  Then, similarly to the first embodiment, the substrate S is selectively irradiated with the first light and the second light. Since the second light has a half-wavelength phase difference from the first light, interference exposure is realized, and the range around the light intensity 0 becomes clear. As a result, a contrast pattern can be formed.

  Next, a third embodiment will be described with reference to FIGS. In the third embodiment, the light from the light source is divided by the DMD, and after the phase difference is created, the two lights are selectively irradiated.

  FIG. 8 is a diagram showing an illumination system in the third embodiment. FIG. 9 is a schematic block diagram of the inside of the exposure head in the third embodiment. FIG. 10 is a diagram illustrating the posture of the micromirror and the light reflection direction in the third embodiment.

  The light source unit 221 of the illumination system 220 is configured by laser oscillation and emits coherent light. The light emitted from the light source 121 enters the DMD 30 via the illumination optical system 222 and the mirror 223.

  As shown in FIG. 8, the light from the light source 121 enters at a predetermined angle (here, 24 °) with respect to the surface vertical direction V of the DMD 30. The micromirror M reflects light toward the surface vertical direction V when in the ON state (12 °), and reflects light in a predetermined direction (−48 °) when in the OFF state (−12 °).

  Therefore, two lights (hereinafter referred to as first light and second light) are generated by selectively irradiating the postures of the ON state and the OFF state. By selectively switching the ON / OFF state of each micromirror M, the pattern light including the first and second lights travels toward the substrate S.

  On the other hand, when the micromirror M is in a flat state, the micromirror M reflects incident light in a direction (−24 °) different from the traveling direction of the first and second lights. Therefore, light is guided outside the substrate by positioning the micromirror in a flat state.

  As shown in FIG. 8, the first light is incident on a light combining optical system 225 provided with light separating means such as a half mirror via a mirror 224A. The first light changes its traveling direction by 90 ° in the light combining optical system 225. The first light emitted from the light combining optical system 225 enters the image forming optical system 40 along the optical axis E3 of the image forming optical system 40.

  On the other hand, the second light is reflected by the mirror 224B, passes through the phase shift plate 224, and then enters the light combining optical system 225. The second light has a half-wavelength phase difference from the first light by the phase shift plate 224. The second light passes through the half mirror of the light combining optical system 225 and enters the imaging optical system 40 along the optical axis of the imaging optical system 40. In addition, there exists a cube prism etc. as a photosynthetic optical system.

  As a result, the first light and the second light having a phase difference of half wavelength selectively enter the substrate S, and interference exposure is realized. As for the attitude of the micromirror for performing interference exposure, either the first light or the second light is projected onto the substrate with respect to the micromirror that forms the pattern light. In particular, when adjacent patterns are formed, the diffracted light of the pattern light is projected onto the non-exposure target area that separates the patterns (between them). For the micromirror that projects light to form the pattern, the micromirror corresponding to one pattern is set to the ON state, the micromirror corresponding to the other pattern is set to the OFF state, and the non-exposure target area is set. What is necessary is just to set to a flat state with respect to an applicable micromirror.

  In order to realize interference exposure equivalent to that of the halftone phase mask, the micromirror that projects pattern light may be positioned in the ON state, and the micromirror corresponding to the non-exposure area may be positioned in the OFF state. In this case, in order to suppress the intensity of the second light to several percent with respect to the first light, the second light and the pattern diffracted light of the first light interfere with each other in the non-exposed area. A configuration in which a weakening optical element is arranged can be applied.

  As described above, according to the third embodiment, the illumination light emitted from the light source unit 221 is separated into the first light and the second light depending on the posture of each micromirror that forms the pattern light of the DMD 30. Then, the second light is combined with the first light in a state where the phase is shifted by a half wavelength. Pattern light composed of the first light and the second light is projected onto the substrate. On the other hand, the micromirror corresponding to the non-exposure area is positioned in a flat state, and as a result, the substrate is not irradiated.

  As described above, the first light and the second light are generated from the illumination light, and after having a phase difference corresponding to a half wavelength, the substrate is irradiated to perform interference exposure. Since the first and second lights are generated based on the configuration of the optical system from the illumination optical system to the imaging optical system, it is possible to realize interference exposure while using the conventional light source unit as it is.

  In the first and second embodiments, a laser oscillator is applied as a light source. However, coherent light may be emitted using an LED or a discharge lamp. Further, the above-described optical systems such as the illumination optical system, the imaging optical system, and the light splitting optical system can also be configured in accordance with the specifications of the exposure apparatus and the like.

  In the first and second embodiments, interference exposure in which a light intensity distribution overlaps each other in a non-exposure target area where the micromirror does not project light has a half-wavelength phase difference, and the exposure area and the non-exposure area. Describes interference exposure for projecting light having a phase difference and an intensity difference corresponding to half wavelengths. However, it is also possible to realize interference exposure based on other phase shifts. By the interference exposure, each micromirror independently outputs the first light and the second light so that the non-exposure target area or the exposure target area becomes a clear dark part at the time of pattern formation, and the dark part significantly improves the contrast. What is necessary is just to selectively reflect.

DESCRIPTION OF SYMBOLS 10 Exposure apparatus 20 Illumination system 30 DMD (light modulation element array)
40 Imaging optics

Claims (11)

A light modulation element array in which a plurality of light modulation elements capable of switching the reflection direction of light according to a change in posture are two-dimensionally arranged;
The first light having the coherent, causes incident on the light modulator array along the first direction, the second light having the coherent if there is a phase difference relative to the first light, the first An illumination system that is incident on the light modulation element array on which the first light is incident along a second direction different from the direction ;
An imaging optical system that forms an image on the pattern forming surface of the first and second lights reflected by the light modulation element array;
An exposure control unit for controlling the posture of each of the plurality of light modulation elements according to pattern data;
Each of the plurality of light modulation elements reflects a first light in a direction along the optical axis of the imaging optical system, and a second position along the optical axis of the imaging optical system. It is possible to take a posture at the second position that reflects in the direction,
An exposure apparatus, wherein the exposure control unit selectively positions the plurality of light modulation elements at one of a first position and a second position according to a pattern. 2. The exposure apparatus according to claim 1, wherein the illumination system causes the first light and the second light to be incident at an incident angle having the same absolute value with respect to a vertical direction of the light modulation element array. . The exposure control unit is a light modulation element that projects light onto an exposure target area facing each other with the non-exposure target area sandwiched between the plurality of light modulation elements, and a light intensity distribution in the non-exposure target area. With respect to the light modulation elements that project light overlapping each other, the light modulation element that projects light onto one exposure target area is positioned at the first position, and the light modulation element that projects light onto the other exposure target area is positioned at the second position. The exposure apparatus according to claim 1 , wherein: Each light modulation element has a first position inclined by a predetermined angle from the flat state toward the incident direction of the first light, and a second position inclined by a predetermined angle from the flat state to the incident direction of the second light. The posture can be changed between
The exposure control unit positions a light modulation element for projecting pattern light among the plurality of light modulation elements at one of a first position and a second position, and a light modulation element corresponding to a non-exposure target area On the other side,
The illumination system irradiates one of the first light and the second light incident on the light modulation element corresponding to the non-exposure target area with a light intensity relatively lower than the other light. The exposure apparatus according to claim 1, wherein: A first position inclined by a predetermined angle from the flat state toward the incident direction of the first light; a second position inclined from the flat state by a predetermined angle toward the incident direction of the second light; The posture can be changed between the flat state,
The exposure control unit positions a light modulation element that projects pattern light at a first position with respect to the first light incidence, positions at a second position with respect to the second light incidence , and pattern light. 4. The exposure apparatus according to claim 1 , wherein the light modulation element that does not project the light is positioned in a flat state . The exposure control unit, first, as to image at a second light by a minute exposure area width size of the exposure according to claim 1, characterized in that positioning the plurality of light modulator elements apparatus. First, the intensity of the second light, claim to be a pattern exposure energy or more energy required to form on the substrate a photosensitive surface, characterized in that which is defined in accordance with the sensitivity of the photosensitive member 1 The exposure apparatus described in 1.   The illumination system includes a first light source that emits first light, a second light source that emits second light, and a phase shift optical system that shifts the phase with respect to the first light or the second light. The exposure apparatus according to claim 1, comprising:   The illumination system has a light source that emits illumination light, a splitting optical system that divides the illumination light into first light and second light, and a phase that shifts the phase with respect to the first light or the second light. The exposure apparatus according to claim 1, further comprising a shift optical system.   The exposure apparatus according to claim 1, wherein the first light and the second light are coherent light having a phase difference of ½ wavelength. A light modulation element array in which a plurality of light modulation elements capable of switching the reflection direction of light according to a change in posture are two-dimensionally arranged;
The first light having the coherent, causes incident on the light modulator array along the first direction, the second light having the coherent if there is a phase difference relative to the first light, the first An illumination optical system that is incident on the light modulation element array on which the first light is incident along a second direction different from the direction ;
An imaging optical system that forms an image on the pattern forming surface of the first and second lights reflected by the light modulation element array;
Each of the plurality of light modulation elements reflects a first light in a direction along the optical axis of the imaging optical system, and a second position along the optical axis of the imaging optical system. It is possible to take a posture at the second position that reflects in the direction,
An exposure head, wherein the plurality of light modulation elements are selectively positioned at either a first position or a second position according to a pattern.

Images