Patent Application
20240168386
The present invention relates to a drawing apparatus and a drawing method, and more particularly to a drawing apparatus including a modulator having a diffraction grating and a drawing method using the same.
As a typical exposure method in photolithography, a method of projecting a pattern of a photomask onto a substrate by an optical system has been widely used. On the other hand, a method of drawing a pattern on a photosensitive surface using a drawing head, in other words, direct drawing is also used, and in this case, there is an advantage that the photomask is not required. As a technique of the direct drawing, for example, Japanese Patent Application Laid-Open No. 2015-170838 (Patent Document 1) discloses an exposure method intended to reduce an exposure defect when a film pattern such as wiring is formed on an inclined surface such as a concave portion or a convex portion. According to the above publication, it is claimed that the reduction of the exposure defect is achieved by controlling a polarization state to suppress stray light. In addition, according to the above publication, it is described that there is a limit to a depth of focus (DOF) of a projection optical system in a case where a fine pattern with high resolution is formed on the inclined surface, and thus, it is necessary to divide one inclined surface into a plurality of exposure regions and expose the fine pattern.
With complication of device structures, there is a demand for exposure by the direct drawing on a surface having a stepped structure. A DOF of a drawing apparatus for the direct drawing is typically about several μm to several tens of μm, and in a case where a height difference of the stepped structure greatly exceeds the DOF, a difference between a drawing pattern and a design pattern is likely to increase due to defocus. To cope with such a problem, one inclined surface is divided into the plurality of exposure regions to expose the fine pattern according to the technique of the publication described above. In this method, however, it is necessary to complicatedly adjust focus of an optical system to correspond to each of the regions, and as a result, control of the drawing apparatus becomes complicated. In particular, when the height difference exceeds 100 μm, it is difficult to follow a change in height with a typical autofocus mechanism for the drawing apparatus.
The present invention has been made to solve the above problems, and an object of the present invention is to provide a drawing apparatus and a drawing method capable of drawing a pattern with high accuracy on an exposure surface having a height difference exceeding a DOF without requiring complicated adjustment of a focus of an optical system.
A first aspect is a drawing apparatus that draws at least one drawing pattern on an exposure surface of a substrate, the exposure surface being provided with at least one stepped structure including a step upper surface, a step lower surface having a lower height than the step upper surface, and an inclined surface connecting the step upper surface and the step lower surface to each other, the at least one drawing pattern including at least one stepped pattern drawn at least partially on the inclined surface of the stepped structure, and the at least one stepped pattern extending in a longitudinal direction in a plan view. The drawing apparatus includes: a substrate holding mechanism that holds the substrate on a horizontal plane; a light source; a modulator that includes a diffraction grating including a plurality of diffractive elements arrayed in an array direction and modulates light from the light source; a projection optical system including an objective lens disposed between the exposure surface and the modulator; a rotation mechanism that rotates the substrate in the horizontal plane; and a controller that controls the rotation mechanism to adjust an orientation of the substrate on the horizontal plane such that the longitudinal direction of the at least one stepped pattern substantially coincides with an orthogonal direction orthogonal to the array direction of the diffraction grating in the plan view.
A second aspect is the drawing apparatus of the first aspect, further including an illumination optical system provided between the light source and the diffraction grating, the illumination optical system supplying light from the light source to the diffraction grating as parallel light in the array direction.
A third aspect is the drawing apparatus of the first or second aspect, in which the plurality of diffractive elements is arrayed only in the array direction.
A fourth aspect is the drawing apparatus of any one of the first to third aspects, in which the controller includes an extractor that extracts, as first pattern data, data representing one of the at least one stepped pattern having a longitudinal direction within a first allowable angle range with a first substrate orientation of the substrate as a reference.
A fifth aspect is the drawing apparatus of the fourth aspect, in which the first allowable angle range is ±10 degrees.
A sixth aspect is the drawing apparatus of the fourth or fifth aspect, in which the extractor extracts, as second pattern data, data representing one of the at least one stepped pattern having a longitudinal direction within a second allowable angle range with a second substrate orientation, different from the first substrate orientation, of the substrate as a reference.
A seventh aspect is the drawing apparatus of the sixth aspect, in which the second substrate orientation is orthogonal to the first substrate orientation.
An eighth aspect is a drawing method of drawing at least one drawing pattern on an exposure surface of a substrate, the exposure surface being provided with at least one stepped structure including a step upper surface, a step lower surface having a lower height than the step upper surface, and an inclined surface connecting the step upper surface and the step lower surface to each other, the at least one drawing pattern including at least one stepped pattern drawn at least partially on the inclined surface of the stepped structure, and the at least one stepped pattern extending in a longitudinal direction in a plan view. The drawing method includes the steps of: (a) holding the substrate on a horizontal plane; (b) adjusting an orientation of the substrate on the horizontal plane; and (c) irradiating, via an objective lens, the exposure surface with light modulated by a modulator which includes a diffraction grating including a plurality of diffractive elements arrayed in an array direction, step (b) being performed such that the longitudinal direction of the at least one stepped pattern substantially coincides with a direction orthogonal to the array direction of the diffraction grating in the plan view.
According to each of the above-described aspects, the orientation of the substrate is adjusted such that the longitudinal direction of the at least one stepped pattern substantially coincides with the orthogonal direction orthogonal to the array direction of the diffraction grating in the plan view. As a result, it is possible to draw the pattern with high accuracy on the exposure surface having the height difference exceeding the DOF without requiring the complicated adjustment of the focus of the optical system.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the same or corresponding portions in the following drawings will be denoted by the same reference signs, and the description thereof will not be repeated. In addition, an X axis, a Y axis, and a Z axis in an XYZ orthogonal coordinate system are illustrated in some drawings for easy understanding of a directional relationship between the drawings.
The substrate W is, for example, a silicon wafer, a resin substrate, or a glass-quartz substrate. The substrate W is, for example, a semiconductor substrate, a printed board, a substrate for a color filter, a glass substrate for a flat panel display, a substrate for a magnetic disk, a substrate for an optical disk, or a panel for a solar cell. The substrate for a color filter is used in, for example, a liquid crystal display apparatus or the like. The glass substrate for a flat panel display is used in, for example, a liquid crystal display apparatus or a plasma display apparatus.
The drawing apparatus 100 may include a main body frame 2. The main body frame 2 constitutes a housing of the drawing apparatus 100. A processing region 3 and a delivery region 4 are formed inside the main body frame 2. The processing region 3 and the delivery region 4 are divided from each other. The drawing apparatus 100 may further include a base 5, a support frame 6, a cassette placement part 7, a stage 10 (substrate holding mechanism), a driving mechanism 20, a stage position measuring part 30, an optical unit 40, a conveyance apparatus 50, and the controller 60. The base 5, the support frame 6, the stage 10, the driving mechanism 20, the stage position measuring part 30, and the optical unit 40 are installed in the processing region 3. The conveyance apparatus 50 is installed in the delivery region 4. The cassette placement part 7 is installed outside the main body frame 2. Hereinafter, a configuration of each part included in the drawing apparatus 100 will be described.
The base 5 supports the stage 10. The support frame 6 is installed on the base 5. The support frame 6 supports the optical unit 40.
The stage 10 holds the substrate W. The stage 10 has a flat plate shape. A placement surface 11 on which the substrate W can be placed is formed on an upper surface of the stage 10. A plurality of suction holes (not illustrated) is formed in the placement surface 11 of the stage 10. As a negative pressure (suction pressure) is formed in the suction holes of the stage 10, the substrate W placed on the placement surface 11 of the stage 10 is fixed to the stage 10. As a result, the stage 10 holds the substrate W.
The driving mechanism 20 is controlled by the controller 60 to relatively move the stage 10 and the head part 402 in the horizontal direction. Specifically, the driving mechanism 20 moves the stage 10 along a main-scanning direction Y, a sub-scanning direction X, and the rotation direction θ. The main-scanning direction Y is a positive-side direction of the Y axis illustrated in
The driving mechanism 20 includes a rotation mechanism 21, a support plate 22, a sub-scanning mechanism 23, a base plate 24, and a main-scanning mechanism 25. The rotation mechanism 21 includes a motor that rotates the stage 10 in order to rotate the substrate W in the horizontal plane. The support plate 22 supports the stage 10 via the rotation mechanism 21. The sub-scanning mechanism 23 moves the support plate 22 along the sub-scanning direction X. The base plate 24 supports the support plate 22 via the sub-scanning mechanism 23. The main-scanning mechanism 25 moves the base plate 24 along the main-scanning direction Y.
The rotation mechanism 21 rotates the stage 10 about a rotation axis A. The rotation axis A is an axis that passes through the center of the stage 10 and is parallel to the Z axis. The rotation mechanism 21 includes, for example, a rotation shaft 211 and a rotational driving part 212. The rotation shaft 211 is fixed to the back side of the placement surface 11 and extends along the Z axis. The rotational driving part 212 includes, for example, a motor. The rotational driving part 212 is provided at a lower end of the rotation shaft 211 and rotates the rotation shaft 211. When the rotational driving part 212 rotates the rotation shaft 211, the stage 10 rotates about the rotation axis A.
The sub-scanning mechanism 23 includes a linear motor 231. The linear motor 231 includes a movable element and a stator. The movable element is attached to a lower surface of the support plate 22. The stator is laid on an upper surface of the base plate 24. A pair of guide members 232 extending in the sub-scanning direction X is laid on the base plate 24. A ball bearing is installed between each of the guide members 232 and the support plate 22. The ball bearing slides along the guide member 232. The support plate 22 is supported by the pair of guide members 232 via the ball bearings. When the linear motor 231 operates, the support plate 22 moves along the sub-scanning direction X while being guided by the guide members 232.
The main-scanning mechanism 25 includes a linear motor 251. The linear motor 251 includes a movable element and a stator. The movable element is attached to a lower surface of the base plate 24. The stator is laid on the base 5 of the drawing apparatus 100. A pair of guide members 252 extending in the main-scanning direction Y is laid on the base 5. For example, an air bearing is installed between each of the guide members 252 and the base plate 24. Air is supplied from utility equipment to the air bearing. The base plate 24 floats on the guide members 252 by the air bearings. As a result, the base plate 24 is supported in a non-contact state with respect to the guide members 252. When the linear motor 251 operates, the base plate 24 moves along the main-scanning direction Y while being guided by the guide member 252. At this time, generation of friction between the base plate 24 and the guide member 252 is avoided.
The stage position measuring part 30 measures a position of the stage 10. The stage position measuring part 30 includes, for example, a laser interferometric length measuring machine. For example, the stage position measuring part 30 emits a laser beam from the outside of the stage 10 toward the stage 10, and receives the laser beam reflected by the stage 10. Then, the stage position measuring part 30 measures the position of the stage 10 from the interference between the laser light emitted toward the stage 10 and the laser light reflected by the stage 10. The position of the stage 10 indicates a position in the main-scanning direction Y and a position in the rotation direction θ.
The conveyance apparatus 50 carries the substrate W into the processing region 3 and carries the substrate W out of the processing region 3. The conveyance apparatus 50 includes a plurality of hands 51 and a hand driving mechanism 52. The hand 51 conveys the substrate W. The hand driving mechanism 52 drives the hand 51. The unprocessed substrate W is accommodated in the cassette placement part 7. The conveyance apparatus 50 takes the substrate W out of the cassette placement part 7 and carries the substrate W into the processing region 3, and carries the processed substrate W out of the processing region 3 and accommodates the processed substrate W in the cassette C.
The optical unit 40 irradiates the substrate W held on the stage 10 with drawing light to draw a pattern on the substrate W. The pattern is a general pattern such as a hole, a trench, and a gate. The optical unit 40 includes a light source part 401 and a head part 402 (drawing head), each of which is controlled by the controller 60. The light source part 401 is installed on the support frame 6. The head part 402 is accommodated inside an attached box attached to the support frame 6.
The light source part 401 includes a laser driving part 41, a laser oscillator 42 (light source), and an illumination optical system 43. The laser oscillator 42 is driven by the laser driving part 41, and emits a spot beam, which is a laser beam, from an output mirror (not illustrated). A wavelength of the laser beam is typically i-line. The spot beam is incident on the illumination optical system 43. The illumination optical system 43 generates linear light from the spot beam. The linear light is a line beam having a substantially uniform intensity distribution and a strip-shaped light flux cross section. The line beam is incident on the head part 402. Hereinafter, the line beam incident on the head part 402 is sometimes described as incident light. Note that it may be configured such that a light amount of the incident light is adjusted by applying an aperture to the incident light at a stage before the incident light is incident on the head part 402.
The incident light is subjected to spatial modulation according to pattern data in the head part 402. Spatially modulating the incident light indicates changing a spatial distribution of the incident light. In general, the spatial distribution of the incident light indicates, for example, an amplitude of the light, a phase of the light, and/or polarization. The spatial distribution of the incident light is generated, for example, by rasterizing the design data of the pattern generated using CAD. The pattern data is information in which information indicating irradiation positions of the drawing light with respect to the substrate W are recorded in units of pixels. The drawing apparatus 100 acquires information indicating the pattern data in advance at the time of a drawing operation, and stores the information in the controller 60.
The head part 402 includes a modulator 44 (specifically, a spatial light modulator), a projection optical system 45, and a mirror 46. The incident light incident on the head part 402 is incident on the modulator 44 at a predetermined angle via the mirror 46. The modulator 44 modulates light from the light source part 401 to generate modulated light. Specifically, the modulator 44 spatially modulates the incident light to be divided into the drawing light and unnecessary light. Out of the modulated light, the drawing light is light that contributes to the pattern drawing, and the unnecessary light is light that does not contribute to the pattern drawing. The projection optical system 45 blocks the unnecessary light out of the modulated light incident from the modulator 44 and guides the drawing light to the substrate W. At this time, the projection optical system 45 focuses the drawing light on a focus position in the height direction over the stage 10. The focus position may be determined with reference to a measurement result by the stage position measuring part 30. The pattern is drawn on the substrate W by moving the stage 10 by the driving mechanism 20 while causing the drawing light to be incident on the substrate W.
The modulator 44 includes a diffraction grating 440 formed of a plurality of diffractive elements MU. The plurality of diffractive elements MU is arrayed in an array direction GX along the X direction. The plurality of diffractive elements MU is arrayed only in the array direction GX, and is not arrayed in the other directions. In other words, the plurality of diffractive elements MU is arrayed one-dimensionally instead of two-dimensionally. Thus, the modulator 44 is a one-dimensional modulator. As the one-dimensional modulator, a grating light valve (GLV) (“GLV” is a registered trademark of Silicon Light Machines) which is a micro electro mechanical systems (MEMS) device manufactured using a semiconductor device manufacturing technique is well known, and can be used as the modulator 44 in the present embodiment. Note that a digital mirror device (DMD) is well known as a two-dimensional modulator.
The GLV has a plurality of pixels (modulation units) configured by the diffraction grating 440. Each of the pixels includes at least one diffractive element MU, and typically includes a plurality of diffractive elements MU adjacent to each other. Therefore, the plurality of pixels is arranged in the array direction GX.
The GLV includes the diffraction grating 440, a common electrode 444, a substrate part 446, and a driver circuit unit 450. The diffraction grating 440 includes fixed ribbons 441 and movable ribbons 442 alternately arrayed in the array direction GX. Each of the fixed ribbon 441 and the movable ribbon 442 has a function as a micromirror. One fixed ribbon 441 and one movable ribbon 442 adjacent to each other constitute one diffractive element MU. Each of the fixed ribbon 441 and the movable ribbon 442 has a portion facing the common electrode 444 with an air gap interposed therebetween. A position of the movable ribbon 442 in a depth direction GZ can be controlled by deflection caused by an electrostatic force generated according to a voltage signal from the driver circuit unit 450. The voltage signal can be independently controlled in units of pixels. On the other hand, such a voltage signal is not applied to the fixed ribbon 441, and thus, a depth position of the fixed ribbon 441 is fixed. When an orthogonal direction GY is defined as a direction orthogonal to the array direction GX, each of the fixed ribbon 441 and the movable ribbon 442 extends along the orthogonal direction GY on the air gap in a state where no voltage signal is applied. The array direction GX, the orthogonal direction GY, and the depth direction GZ may be orthogonal to each other.
In the pixel PXON, as indicated by a two-dot chain line in
To give a specific configuration of the GLV as an example, 8000 micromirrors (ribbons) are arrayed over a width of 4 mm in the array direction GX, and one pixel PX includes four mirrors (two diffractive elements MU). As a result, 2000 pixels PX are provided in the array direction GX, and the minimum resolution in the width direction GX is 4 mm/2000=2 μm.
The illumination optical system 43 is disposed between the light source 42 (not illustrated in
The projection optical system 45 is disposed between the diffraction grating 440 of the modulator 44 and the exposure surface PE. The projection optical system 45 includes a Fourier transform lens 451, a Fourier filter 452, and an inverse Fourier transform lens 453 (objective lens) in the order of the traveling direction of the optical path between the modulator 44 and the exposure surface PE. A magnification that can be obtained by the objective lens is determined by a ratio f2/f1, where f1 is a focal length of the Fourier transform lens 451 and f2 is a focal length of the inverse Fourier transform lens 453. The Fourier filter 452 is a filter that blocks the ± first-order diffracted light L±1 having passed through the Fourier transform lens 451 while transmitting the zero-order diffracted light L0 of the diffraction grating 440 having passed through the Fourier transform lens 451, and specifically, is a blocking plate having an aperture that transmits the zero-order diffracted light L0. Drawing is performed by irradiating the exposure surface PE with light emitted from the inverse Fourier transform lens 453. Two-dot chain lines drawn rightward beyond the exposure surface PE in
In the exposure scanning, the driving mechanism 20 moves the stage 10 in a forward direction (here, exemplified as the +Y direction) along the main-scanning direction (Y direction) to relatively move the substrate W along a main-scanning axis with respect to each of the head parts 402 (forward main-scanning). When viewed from the substrate W, each of the head parts 402 traverses the substrate W in the −Y direction along the main-scanning axis as indicated by an arrow AR11. In addition, as the forward main-scanning is started, the drawing light is emitted from each of the head parts 402. That is, pattern data (specifically, a portion, which describes data that needs to be drawn in a stripe region to be drawn by the forward main-scanning, of the pattern data) is read, and the modulator 44 is controlled according to the pattern data. Then, drawing light subjected to spatial modulation according to the pattern data is emitted from each of the head parts 402 toward the substrate W.
When each of the head parts 402 traverses the substrate W once along the main-scanning axis while emitting the drawing light continuously or intermittently toward the substrate W, a pattern group is drawn in one stripe region (region extending along the main-scanning axis and having a width along a sub-scanning axis corresponding to a width of the drawing light). Here, pattern groups are drawn in two stripe regions, respectively, by one forward main-scanning since the two head parts 402 simultaneously traverse the substrate W.
When the forward main-scanning involving the irradiation of the drawing light is completed, the driving mechanism 20 moves the stage 10 in a predetermined direction (for example, in the −X direction) along the sub-scanning direction (X direction) by a distance corresponding to the width of the drawing light. Accordingly, the substrate W moves relative to each of the head parts 402 along the sub-scanning direction (sub-scanning). When viewed from the substrate W, each of the head parts 402 moves in the +X direction along the sub-scanning direction by the width of the stripe region as indicated by an arrow AR12.
When the sub-scanning is completed, backward main-scanning involving the irradiation of the drawing light is executed. That is, the driving mechanism 20 moves the stage 10 in the backward direction (here, in the −Y direction,) along the main-scanning direction (Y direction). Accordingly, the substrate W moves relative to each of the head parts 402 along the main-scanning direction (backward main-scanning). When viewed from the substrate W, each of the head parts 402 moves in the +Y direction along the main-scanning direction on the substrate W to traverse the substrate W as indicated by an arrow AR13. In the meantime, when the backward main-scanning is started, the irradiation of the drawing light is started from each of the head parts 402. This backward main-scanning causes pattern groups to be drawn in stripe regions respectively adjacent to the stripe regions subjected to the drawing in the previous forward main-scanning.
When the backward main-scanning involving the irradiation of the drawing light ends, sub-scanning is performed, and then, the forward main-scanning involving the irradiation of the drawing light is performed again. This forward main-scanning causes pattern groups to be drawn in stripe regions respectively adjacent to the stripe regions subjected to the drawing in the previous backward main-scanning. Thereafter, similarly, the main-scanning involving the irradiation of the drawing light is repeatedly performed while interposing the sub-scanning, and when the pattern is drawn in the entire region of the drawing target region, the drawing processing for one piece of the pattern data ends.
The storage 61 stores data representing a drawing pattern to be drawn on the substrate W. For example, as illustrated in the upper part of
As illustrated in
In addition, as illustrated in
Note that, as a modification, the extractor 62 may extract, as third pattern data, data representing a stepped pattern having a longitudinal direction within a third allowable angle range with a third substrate orientation, which is a substrate orientation between the substrate orientation WX and the substrate orientation WY, as a reference, among the stepped patterns. The third substrate orientation may be, for example, a substrate orientation rotated clockwise by 45 degrees from the substrate orientation WY. In this case, exposure scanning in a third mode in which the substrate W has an intermediate orientation between the case of the first mode (
The rotation adjuster 63 (
Next, the drawing method in the present embodiment will be exemplified.
In step ST10 (
In step ST20 (
In step ST40 (
In step ST50 (
In step ST70 (
As described above, both the stepped pattern PTX and the stepped pattern PTY are drawn. A drawing pattern other than the stepped pattern PTX and the stepped pattern PTY may be drawn simultaneously by either the exposure scanning in the first mode or the exposure scanning in the second mode.
In each exposure scanning described above, a focus position of the modulated light (a focus position at a right end of the optical path illustrated in
Note that the case where the drawing pattern has the L/S shape has been described in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-068429 | Apr 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/017464 | 4/11/2022 | WO |
