Drawing device and drawing method

Abstract

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 depth of focus.SOLUTION: At least one drawing pattern includes at least one step pattern drawn at least partially on an inclined surface of a step structure. At least one step pattern extends longitudinally in a plan view. A modulator 44 has a diffraction grating composed of a plurality of diffraction elements arranged in an arrangement direction GX. A rotating mechanism 21 rotates a substrate W within a horizontal plane. A control unit 60 controls the rotation mechanism 21 so as to adjust a direction of the substrate W in a horizontal plane such that a longitudinal direction of at least one step pattern and an orthogonal direction GY orthogonal to the arrangement direction GX substantially coincide in plan view.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] 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. [Background technology]

[0002] As a representative exposure method in photolithography, a method of projecting a pattern of a photomask onto a substrate by an optical system is 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, which has the advantage of not requiring a photomask. As a direct drawing technique, for example, JP 2015-170838 A (Patent Document 1) discloses an exposure method intended to reduce exposure failures when forming a film pattern such as wiring on an inclined surface such as a concave or convex portion. The above publication asserts that the reduction of exposure failures is achieved by suppressing stray light by controlling the polarization state. The above publication also describes that when forming a fine pattern with high resolution on an inclined surface, it is necessary to expose the fine pattern by dividing one inclined surface into multiple exposure areas because there is a limit to the depth of focus (DOF) of the projection optical system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-170838 A Summary of the Invention [Problem to be solved by the invention]

[0004] As device structures become more complex, exposure by direct writing on a surface having a step structure is required. The DOF of a writing device for direct writing is typically several μm to several tens of μm, and when the height difference of the step structure greatly exceeds the DOF, the difference between the written pattern and the design pattern is likely to become large due to defocus. In response to this problem, according to the technology of the above publication, one inclined surface is divided into multiple exposure areas and a fine pattern is exposed. However, in this method, the focus of the optical system needs to be adjusted in a complex manner corresponding to each area, and as a result, the control of the writing device becomes complicated. In particular, when the height difference exceeds 100 μm, it is difficult for a typical autofocus mechanism for a writing device to follow the height change.

[0005] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a drawing apparatus and a drawing method that can draw a pattern with high precision on an exposure surface having a height difference exceeding the DOF, without the need for complex adjustments to the focus of the optical system. [Means for solving the problem]

[0006] A first aspect is a drawing apparatus for drawing at least one drawing pattern on an exposure surface on a substrate, the exposure surface being provided with at least one step structure having a step upper surface, a step lower surface having a height lower than the step upper surface, and an inclined surface connecting the step upper surface and the step lower surface, the at least one drawing pattern including at least one step pattern that is at least partially drawn on the inclined surface of the step structure, the at least one step pattern extending in a longitudinal direction in a plan view, and the drawing apparatus drawing at least one drawing pattern on the substrate. The projection optical system includes a substrate holding mechanism that holds the substrate on a horizontal plane, a light source, a modulator having a diffraction grating composed of a plurality of diffraction elements arranged in an arrangement direction and that modulates light from the light source, and an objective lens arranged between the exposure surface and the modulator, a rotation mechanism that rotates the substrate within the horizontal plane, and a control unit that controls the rotation mechanism so that the orientation of the substrate on the horizontal plane is adjusted so that the longitudinal direction of the at least one step pattern and an orthogonal direction perpendicular to the arrangement direction of the diffraction grating approximately coincide in a plan view.

[0007] A second aspect is the drawing device of the first aspect, further comprising an illumination optical system between the light source and the diffraction grating, the illumination optical system providing light from the light source to the diffraction grating as parallel light in the arrangement direction.

[0008] A third aspect is the imaging device of the first or second aspect, wherein the plurality of diffractive elements are arranged only in the arrangement direction.

[0009] A fourth aspect is a drawing device of any one of the first to third aspects, wherein the control unit includes an extraction unit that extracts, as first pattern data, data representing one of the at least one step pattern having a longitudinal direction within a first allowable angle range based on a first substrate orientation of the substrate.

[0010] A fifth aspect is the imaging device according to the fourth aspect, wherein the first allowable angle range is ±10 degrees.

[0011] A sixth aspect is a drawing device of the fourth or fifth aspect, wherein the extraction unit extracts, as second pattern data, data representing one of the at least one step pattern having a longitudinal direction within a second allowable angle range based on a second substrate orientation different from the first substrate orientation of the substrate.

[0012] A seventh aspect is the drawing apparatus of the sixth aspect, wherein the second substrate orientation is orthogonal to the first substrate orientation.

[0013] An eighth aspect is a drawing method for drawing at least one drawing pattern on an exposure surface on a substrate, the exposure surface having at least one step structure having a step upper surface, a step lower surface having a height lower than the step upper surface, and an inclined surface connecting the step upper surface and the step lower surface, the at least one drawing pattern includes at least one step pattern that is drawn at least partially on the inclined surface of the step structure, the at least one step pattern extending in a longitudinal direction in a planar view, the drawing method comprising: (a) a step of holding the substrate on a horizontal plane; (b) a step of adjusting an orientation of the substrate in the horizontal plane; and (c) a step of irradiating the exposure surface via an objective lens with light modulated by a modulator having a diffraction grating composed of a plurality of diffraction elements arranged in an arrangement direction, the step (b) being performed so that the longitudinal direction of the at least one step pattern and a direction perpendicular to the arrangement direction of the diffraction grating are approximately coincident in a planar view. Effect of the Invention

[0014] According to each of the above aspects, the orientation of the substrate is adjusted so that the longitudinal direction of at least one step pattern and the orthogonal direction perpendicular to the arrangement direction of the diffraction grating are substantially aligned in a plan view, which allows a pattern to be written with high accuracy on an exposure surface having a height difference exceeding the DOF without the need for complex adjustment of the focus of the optical system. [Brief description of the drawings]

[0015] [Figure 1]1 is a side view illustrating a schematic configuration of a drawing apparatus according to an embodiment. [Diagram 2] FIG. 2 is a plan view illustrating a schematic configuration of the drawing apparatus of FIG. [Diagram 3] 2 is a partial cross-sectional view for explaining the configuration and operation principle of a modulator included in the drawing apparatus of FIG. 1. [Figure 4] 2 is a partial cross-sectional view for explaining the configuration and operation principle of a modulator included in the drawing apparatus of FIG. 1. [Diagram 5] 2 is a diagram for explaining a schematic diagram of an optical path in an optical unit of the imaging apparatus of FIG. 1. [Figure 6] 2 is a diagram for explaining a schematic diagram of an optical path in an optical unit of the imaging apparatus of FIG. 1. [Figure 7] 2 is a block diagram illustrating a hardware configuration of a control unit in FIG. 1. [Figure 8] FIG. 2 is a plan view illustrating an exposure scan in a first mode in the writing method according to the embodiment. [Figure 9] FIG. 11 is a plan view illustrating an exposure scan in a second mode in the writing method according to the embodiment. [Figure 10] 2 is a partial plan view illustrating an example of an exposed surface of a substrate; [Figure 11] FIG. 11 is a partial cross-sectional view taken along line XI-XI in FIG. [Figure 12] FIG. 1 is a partial plan view showing an example of an apparatus that requires drawing a step pattern. [Figure 13] FIG. 13 is a partial cross-sectional view taken along line XIII-XIII in FIG. [Figure 14] FIG. 14 is a partial cross-sectional view showing a modification of FIG. [Figure 15] 2 is a functional block diagram illustrating a schematic configuration of a control unit in FIG. 1. [Figure 16] 2 is a partial plan view for explaining the function of a control unit in FIG. 1. FIG. [Figure 17] 2 is a partial plan view for explaining the function of a control unit in FIG. 1. FIG. [Figure 18] FIG. 2 is a flow diagram illustrating a schematic drawing method according to an embodiment. [Figure 19] FIG. 2 is a plan view illustrating a schematic process of a writing method according to an embodiment. [Figure 20] FIG. 2 is a plan view illustrating a schematic process of a writing method according to an embodiment. [Figure 21] FIG. 2 is a plan view illustrating a schematic process of a writing method according to an embodiment. [Figure 22] FIG. 4 is a partial cross-sectional view that illustrates a schematic view of an exposure scanning process in a first comparative example. [Diagram 23] 23 is a partial plan view showing a resist pattern obtained by the exposure scanning of FIG. 22. [Figure 24] FIG. 11 is a diagram illustrating exposure scanning in a second comparative example. [Diagram 25] FIG. 2 is a diagram illustrating exposure scanning in an embodiment. [Figure 26] 26 is a photomicrograph showing an example of the exposure scan of FIG. 25. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the same or corresponding parts in the following drawings are given the same reference numerals and their description will not be repeated. In addition, in some drawings, the X-axis, Y-axis, and Z-axis in an XYZ Cartesian coordinate system are shown to make the relationship of directions between the drawings easier to understand.

[0017] <Drawing device> 1 and 2 are a side view and a plan view, respectively, that show a schematic configuration of a drawing apparatus 100. The drawing apparatus 100 exposes a photosensitive layer such as a photoresist formed on an exposure surface PE of a substrate W by irradiating the exposure surface PE with drawing light modulated according to predetermined data. This exposure results in drawing at least one drawing pattern, such as a circuit pattern. The predetermined data is data representing a pattern, such as CAD (Computer-Aided Design) data. By using the drawing apparatus 100, it is possible to draw a pattern directly on the photosensitive layer, in other words, direct drawing. Direct drawing has the advantage that no exposure mask is required.

[0018] 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 circuit 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, for example, in a liquid crystal display device. The glass substrate for a flat panel display is used, for example, in a liquid crystal display device or a plasma display device. In FIG. 2, a circular semiconductor substrate is illustrated as the substrate W. The shape of the substrate W is not particularly limited. The substrate W may be formed, for example, in a rectangular shape.

[0019] The drawing apparatus 100 may have a main body frame 2. The main body frame 2 constitutes a housing of the drawing apparatus 100. Inside the main body frame 2, a processing area 3 and a delivery area 4 are formed. The processing area 3 and the delivery area 4 are separated from each other. The drawing apparatus 100 may further have a base 5, a support frame 6, a cassette placement unit 7, a stage 10 (substrate holding mechanism), a driving mechanism 20, a stage position measurement unit 30, an optical unit 40, a transport device 50, and a control unit 60. The base 5, the support frame 6, the stage 10, the driving mechanism 20, the stage position measurement unit 30, and the optical unit 40 are installed in the processing area 3. The transport device 50 is installed in the delivery area 4. The cassette placement unit 7 is installed outside the main body frame 2. The configuration of each unit included in the drawing apparatus 100 will be described below.

[0020] 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.

[0021] The stage 10 holds a substrate W. The stage 10 has a flat plate-like shape. A mounting surface 11 on which the substrate W can be placed is formed on the upper surface of the stage 10. A plurality of suction holes (not shown) are formed in the mounting surface 11 of the stage 10. A negative pressure (suction pressure) is generated in the suction holes of the stage 10, so that the substrate W placed on the mounting surface 11 of the stage 10 is fixed to the stage 10. As a result, the stage 10 holds the substrate W.

[0022] The driving mechanism 20 is controlled by the control unit 60 to relatively move the stage 10 and the head unit 402 in the horizontal direction. Specifically, the driving mechanism 20 moves the stage 10 along the main scanning direction Y, the sub-scanning direction X, and the rotation direction θ. The main scanning direction Y is the + side direction of the Y axis shown in Figs. 1 and 2. The sub-scanning direction X is the + side direction of the X axis shown in Figs. 1 and 2. The rotation direction θ is the rotation direction around the Z axis shown in Fig. 2. In this embodiment, the + side direction of the Z axis indicates the vertical upward direction. The mounting surface 11 of the stage 10 is parallel to each of the X axis and the Y axis, and therefore the stage 10 can mount the substrate W in a posture along the horizontal direction. In other words, the stage 10 can hold the substrate W on a horizontal surface.

[0023] The drive mechanism 20 has 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 has a motor that rotates the stage 10 to rotate the substrate W in a 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.

[0024] The rotation mechanism 21 rotates the stage 10 around a rotation axis A. The rotation axis A passes through the center of the stage 10 and is an axis parallel to the Z axis. The rotation mechanism 21 includes, for example, a rotation shaft unit 211 and a rotation drive unit 212. The rotation shaft unit 211 is fixed to the back side of the mounting surface 11 and extends along the Z axis. The rotation drive unit 212 includes, for example, a motor. The rotation drive unit 212 is provided at the lower end of the rotation shaft unit 211 and rotates the rotation shaft unit 211. The rotation drive unit 212 rotates the rotation shaft unit 211, causing the stage 10 to rotate around the rotation axis A.

[0025] The sub-scanning mechanism 23 has a linear motor 231. The linear motor 231 is composed of a moving element and a stator. The moving element is attached to the lower surface of the support plate 22. The stator is placed on the upper surface of the base plate 24. A pair of guide members 232 extending in the sub-scanning direction X are placed on the base plate 24. A ball bearing is installed between each guide member 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 bearing. When the linear motor 231 operates, the support plate 22 moves along the sub-scanning direction X while being guided by the guide member 232.

[0026] The main scanning mechanism 25 has a linear motor 251. The linear motor 251 is composed of a moving element and a stator. The moving element is attached to the 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 are laid on the base 5. For example, an air bearing is installed between each guide member 252 and the base plate 24. Air is supplied to the air bearing from a utility facility. The base plate 24 floats on the guide member 252 by the air bearing. As a result, the base plate 24 is supported in a non-contact state with respect to the guide member 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, friction between the base plate 24 and the guide member 252 is avoided.

[0027] The stage position measurement unit 30 measures the position of the stage 10. The stage position measurement unit 30 is, for example, configured with an interference type laser length measuring device. For example, the stage position measurement unit 30 emits a laser beam from outside the stage 10 toward the stage 10 and receives the laser beam reflected by the stage 10. The stage position measurement unit 30 then measures the position of the stage 10 from interference between the laser beam emitted toward the stage 10 and the laser beam reflected by the stage 10. The position of the stage 10 indicates the position in the main scanning direction Y and the position in the rotational direction θ.

[0028] The transport device 50 carries the substrate W into the processing region 3 and carries the substrate W out of the processing region 3. The transport device 50 has a plurality of hands 51 and a hand driving mechanism 52. The hand 51 transports the substrate W. The hand driving mechanism 52 drives the hand 51. An unprocessed substrate W is stored in the cassette mounting part 7. The transport device 50 removes the substrate W from the cassette mounting part 7 and carries it into the processing region 3, and also carries out the processed substrate W from the processing region 3 and stores it in a cassette C.

[0029] 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 has a light source unit 401 and a head unit 402 (drawing head), each of which is controlled by the control unit 60. The light source unit 401 is installed on the support frame 6. The head unit 402 is housed inside an attachment box attached to the support frame 6.

[0030] The light source unit 401 has a laser driving unit 41, a laser oscillator 42 (light source), and an illumination optical system 43. The laser oscillator 42 is driven by the laser driving unit 41 to emit a spot beam, which is a laser beam, from an output mirror (not shown). The wavelength of the laser beam is typically an 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 has a substantially uniform intensity distribution and is a line beam with a strip-shaped light beam cross section. The line beam is incident on the head unit 402. Hereinafter, the line beam incident on the head unit 402 may be referred to as incident light. Note that the amount of incident light may be adjusted by narrowing the incident light before the incident light enters the head unit 402.

[0031] The incident light is spatially modulated in the head unit 402 according to the pattern data. Spatially modulating the incident light means changing the spatial distribution of the incident light. In general, the spatial distribution of the incident light indicates, for example, the amplitude of the light, the phase of the light, and / or the polarization. The spatial distribution of the incident light is generated, for example, by rasterizing design data of a pattern generated using CAD. The pattern data is information in which information indicating the irradiation position of the drawing light on the substrate W is recorded in pixel units. During the drawing operation, the drawing apparatus 100 acquires information indicating the pattern data in advance and stores it in the control unit 60.

[0032] The head unit 402 has a modulator 44 (specifically, a spatial light modulator), a projection optical system 45, and a mirror 46. The incident light incident on the head unit 402 is incident on the modulator 44 at a predetermined angle via the mirror 46. The modulator 44 generates modulated light by modulating light from the light source unit 401. Specifically, the modulator 44 spatially modulates the incident light to separate it into drawing light and unnecessary light. Of the modulated light, the drawing light is light that contributes to drawing a pattern, and the unnecessary light is light that does not contribute to drawing a pattern. The projection optical system 45 blocks the unnecessary light 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 at a focus position in the height direction on the stage 10. The focus position may be determined by referring to the measurement result by the stage position measurement unit 30. While the imaging light is incident on the substrate W, the stage 10 is moved by the drive mechanism 20, whereby a pattern is imaged on the substrate W.

[0033] <Modulator details> 3 and 4 are partial cross-sectional views for explaining the configuration and operation principle of modulator 44. Note that Fig. 3 is a partial cross-sectional view taken along line III-III (Fig. 4), and Fig. 4 is a partial cross-sectional view taken along line IV-IV (Fig. 3).

[0034] The modulator 44 has a diffraction grating 440 composed of a plurality of diffraction elements MU. The plurality of diffraction elements MU are arranged in an arrangement direction GX along the X direction. The plurality of diffraction elements MU are arranged only in the arrangement direction GX, and are not arranged in other directions. In other words, the plurality of diffraction elements MU are arranged one-dimensionally, not two-dimensionally. Therefore, the modulator 44 is a one-dimensional modulator. As a one-dimensional modulator, a grating light valve (GLV) ("GLV" is a registered trademark of Silicon Light Machines, Inc.), which is a MEMS (Micro Electro Mechanical Systems: MEMS) device manufactured using semiconductor device manufacturing technology, is well known, and can be used as the modulator 44 in this embodiment. Note that a DMD (Digital Mirror Device) is well known as a two-dimensional modulator.

[0035] The GLV has a number of pixels (modulation units) each of which is made up of a diffraction grating 440. Each pixel is made up of at least one diffraction element MU, and typically is made up of a number of diffraction elements MU adjacent to each other. Thus, the pixels are arranged in the arrangement direction GX. In FIG. 3, a pixel made up of three diffraction elements MU is illustrated, and in the figure, a pixel PX ON is an on-state pixel, and pixel PX OFF are pixels in the off state, and these are collectively referred to as pixels PX. Here, the on state is a state in which the 0th-order diffracted light L0 is emitted as light that contributes to the drawing light, in other words, a state of simple regular reflection. On the other hand, the off state is a state in which no light that contributes to the drawing light is emitted, in other words, the ±1st-order diffracted light L ±1 is emitted.

[0036] The GLV has a diffraction grating 440, a common electrode 444, a substrate portion 446, and a driver circuit unit 450. The diffraction grating 440 has fixed ribbons 441 and movable ribbons 442 arranged alternately in the arrangement direction GX. Each of the fixed ribbons 441 and the movable ribbons 442 has a function as a micromirror. One fixed ribbon 441 and one movable ribbon 442 adjacent to each other constitute one diffraction element MU. Each of the fixed ribbons 441 and the movable ribbons 442 has a portion facing the common electrode 444 via an air gap. The position of the movable ribbon 442 in the depth direction GZ can be controlled by bending due to an electrostatic force generated in response to a voltage signal from the driver circuit unit 450. The voltage signal can be controlled independently on a pixel-by-pixel basis. On the other hand, such a voltage signal is not applied to the fixed ribbons 441, and therefore the depth position is fixed. If the orthogonal direction GY is defined as a direction perpendicular to the array direction GX, then in a state in which no voltage signal is applied, each of the fixed ribbons 441 and the movable ribbons 442 extends along the orthogonal direction GY on the air gap. The array direction GX, the orthogonal direction GY, and the depth direction GZ may be perpendicular to each other.

[0037] Pixel PX ON At , the movable ribbon 442 is not deflected, as shown by the dashed line in FIG. ON The surface of the pixel PX is a plane formed by the movable ribbons 442 and the fixed ribbons 441. ON The surface of the reflector is a plane that is spanned by the arrangement direction GX and the perpendicular direction GY. When light is incident on this plane, the light is specularly reflected. In other words, the zeroth order Occasionally Light L0 is emitted. Occasionally The light L0 reaches the substrate W as drawing light. On the other hand, the pixel PX OFF 4, the movable ribbon 442 is bent, and the pixel PX OFF As shown in FIG. 3, a groove is formed on the surface of the INC When the incident light is a non-zero order diffracted light, specifically, ±1st order diffracted light L ±1, are emitted. These ±1 times Occasionally light L ±1 is blocked as unwanted light before it reaches the substrate W.

[0038] As an example of a specific configuration of the GLV, 8000 micromirrors (ribbons) are arranged over a width of 4 mm in the arrangement direction GX, and one pixel PX is composed of four mirrors (two diffraction elements MU). This provides 2000 pixels PX in the arrangement direction GX, and the minimum resolution in the width direction GX is 4 mm / 2000 = 2 μm.

[0039] <Optical path in the optical unit> Each of Fig. 5 and Fig. 6 is a diagram for explaining the optical path from the light source 42 (see Fig. 1) in the optical unit 40 (Fig. 1). The vertical direction in Fig. 5 corresponds to the arrangement direction GX (i.e., the X direction) at the position of the modulator 44 for the optical path. The vertical direction in Fig. 6 corresponds to a direction perpendicular to the vertical direction in Fig. 5. The horizontal direction in each of Fig. 5 and Fig. 6 corresponds to the traveling direction of the optical path from left to right, and is not a straight line in the actual space, but is bent at the mirror 46 and the modulator 44 as shown in Fig. 1. Therefore, in order to make it easier to understand the directions, the correspondence of directions between the illumination optical system 43, the modulator 44, and the projection optical system 45 is shown at the bottom of Fig. 5 and Fig. 6.

[0040] The illumination optical system 43 is disposed between the light source 42 (not shown in FIGS. 5 and 6) and the diffraction grating 440 of the modulator 44. The illumination optical system 43 includes, in the order of the traveling direction of the optical path, a Powell lens 431 (or a cylinder lens), a collimator lens 432, and a focusing lens 433. With reference to FIG. 5, the Powell lens 431 diffuses light from the light source, thereby extending the light in a linear shape along a direction that corresponds to the arrangement direction GX in the diffraction grating 440, i.e., the X direction in the illumination optical system 43. The collimator lens 432 adjusts the diffused light from the Powell lens 431 into parallel light (collimated light) in a direction that corresponds to the arrangement direction GX in the diffraction grating 440, i.e., the X direction in the illumination optical system 43. The focusing lens 433 approximately focuses the parallel light from the collimator lens 432 onto the modulator 44 in a direction that corresponds to the orthogonal direction GY (FIG. 6) in the diffraction grating 440, while transmitting the parallel light in a direction that corresponds to the array direction GX (FIG. 5) in the diffraction grating 440. Thus, the illumination optical system 43 provides the light from the light source to the diffraction grating 440 as parallel light in the array direction GX. On the other hand, the illumination optical system 43 provides the light from the light source to the diffraction grating 440 as non-parallel light (specifically, convergent light) in the orthogonal direction GY.

[0041] The projection optical system 45 is disposed between the diffraction grating 440 of the modulator 44 and the exposure surface PE. Between the modulator 44 and the exposure surface PE, the projection optical system 45 has, in this order in the traveling direction of the optical path, a Fourier transform lens 451, a Fourier filter 452, and an inverse Fourier transform lens 453 (objective lens). The magnification obtained by the objective lens is determined by the ratio f2 / f1, where f1 is the focal length of the Fourier transform lens 451, and f2 is the focal length of the inverse Fourier transform lens 453. The Fourier filter 452 transmits the 0th order diffracted light L0 of the diffraction grating 440 that has passed through the Fourier transform lens 451, while filtering out the ±1st order diffracted light L1 that has passed through the Fourier transform lens 451. ±1Specifically, it is a filter that blocks the zeroth-order diffracted light L0, and is a blocking plate having an aperture that transmits the zeroth-order diffracted light L0. Drawing is performed by irradiating the light emitted from the inverse Fourier transform lens 453 onto the exposure surface PE. The two-dot chain line drawn to the right beyond the exposure surface PE in Figs. 5 and 6 is a virtual extension of the optical path. As can be seen from these optical paths, the parallelism of the light emitted from the inverse Fourier transform lens 453 as an objective lens is low in the Y direction (Fig. 6), while being relatively high in the X direction (Fig. 5) compared to the Y direction (Fig. 6), and is preferably substantially parallel light.

[0042] <Hardware configuration of the control unit> FIG. 7 is a block diagram illustrating a hardware configuration of the control unit 60. The control unit 60 may be configured by one or more general computers having electric circuits. When a plurality of computers are used, they are connected to each other so as to be able to communicate with each other. The control unit 60 may be disposed in one electrical equipment rack (not shown). Specifically, the control unit 60 has a central processing unit (CPU) 161, a read only memory (ROM) 162, a random access memory (RAM) 163, a storage device 164, an input unit 166, a display unit 167, and a communication unit 168, and a bus line 165 that interconnects these. The ROM 162 stores a basic program. The RAM 163 is used as a work area when the CPU 161 performs a predetermined process. The storage device 164 is configured by a non-volatile storage device such as a flash memory or a hard disk device. The input unit 166 is configured by various switches, a touch panel, a recording medium reader, or the like, and receives input setting instructions such as a processing recipe from an operator. The display unit 167 is composed of, for example, a liquid crystal display device and a lamp, and displays various information under the control of the CPU 161. The communication unit 168 has a data communication function via a local area network (LAN) or the like. A plurality of modes for controlling each component in the drawing device 100 are set in advance in the storage device 164. When the CPU 161 executes the processing program 164P, one of the above-mentioned plurality of modes is selected, and each component is controlled in that mode. The processing program 164P may be stored in a recording medium. By using this recording medium, the processing program 164P can be installed in the control unit 60. Also, some or all of the functions executed by the control unit 60 do not necessarily need to be realized by software, and may be realized by hardware such as a dedicated logic circuit.

[0043] <Exposure Scanning> FIG. 8 is a plan view that shows a schematic exposure scan in the first mode in the writing method according to the present embodiment. In this exposure scan, the exposure scan is performed on the substrate W. The main surface of the substrate W has a substrate orientation WX and a substrate orientation WY that are orthogonal to each other. When the substrate W is held on the stage 10 (FIGS. 1 and 2), each of the substrate orientation WX and the substrate orientation WY is an orientation in the XY plane. The substrate W may have a notch or an orientation flat so that the substrate orientation can be easily determined, and in the illustrated example, a notch NT is provided on the negative side of the substrate orientation WY. In the first mode, the orientation of the substrate W is adjusted so that the substrate orientation WX of the substrate W is aligned with the X direction, and then the following exposure scan is performed. Note that, in the figure, a case where two head units 402 are used is shown, but the number of head units 402 is arbitrary.

[0044] In the exposure scan, the driving mechanism 20 moves the stage 10 in the forward direction (here, the case of +Y direction is illustrated) along the main scanning direction (Y direction), thereby moving the substrate W relatively along the main scanning axis with respect to each head unit 402 (forward main scanning). When viewed from the substrate W, each head unit 402 crosses the substrate W in the -Y direction along the main scanning axis as shown by the arrow AR11. Furthermore, with the start of the forward main scanning, each head unit 402 irradiates the drawing light. That is, the pattern data (more specifically, a portion of the pattern data describing data to be drawn in the stripe region to be drawn by the forward main scanning) is read out, and the modulator 44 is controlled according to the pattern data. Then, the drawing light spatially modulated according to the pattern data is irradiated toward the substrate W from each head unit 402.

[0045] When each head unit 402 traverses the substrate W once along the main scanning axis while continuously or intermittently emitting the drawing light toward the substrate W, a group of patterns is drawn in one stripe region (a region extending along the main scanning axis and whose width along the sub-scanning axis corresponds to the width of the drawing light). In this case, two head units 402 traverse the substrate W simultaneously, so that a group of patterns is drawn in each of the two stripe regions by one outward main scanning.

[0046] When the outward main scan accompanied by irradiation of the drawing light is completed, the drive mechanism 20 moves the stage 10 in a predetermined direction (e.g., the -X direction) along the sub-scanning direction (X direction) by a distance equivalent to the width of the drawing light. This causes the substrate W to move relatively along the sub-scanning direction with respect to each head portion 402 (sub-scanning). When viewed from the substrate W, as indicated by the arrow AR12, each head portion 402 moves in the +X direction along the sub-scanning direction by the width of the stripe region.

[0047] When the sub-scanning is completed, a return main scan is performed accompanied by irradiation of the drawing light. That is, the driving mechanism 20 moves the stage 10 in the return direction (here, the -Y direction) along the main scanning direction (Y direction). This causes the substrate W to move relatively along the main scanning direction with respect to each head unit 402 (return main scan). When viewed from the substrate W, as shown by the arrow AR13, each head unit 402 moves across the substrate W in the +Y direction along the main scanning direction. Meanwhile, when the return main scan is started, each head unit 402 starts irradiating the drawing light. By this return main scan, a group of patterns is drawn in a stripe area adjacent to the stripe area drawn in the previous outward main scan.

[0048] When the backward main scan accompanied by irradiation of the drawing light is completed, a sub-scan is performed, and then an outward main scan accompanied by irradiation of the drawing light is performed again. By this forward main scan, a pattern group is drawn in a stripe area adjacent to the stripe area drawn in the previous backward main scan. Thereafter, similarly, main scans accompanied by irradiation of the drawing light are repeatedly performed with sub-scans interposed therebetween, and when a pattern is drawn in the entire region to be drawn, the drawing process for one pattern data is completed.

[0049] 9 is a plan view illustrating an outline of exposure scanning in the second mode in the writing method according to the present embodiment. In the second mode, the orientation of the substrate W is adjusted so that the substrate orientation WY of the substrate W is aligned with the X direction, and then the same exposure scanning as in FIG. 8 is performed.

[0050] FIG. 10 is a partial plan view illustrating an exposure surface PE of a substrate W, and FIG. 11 is a partial cross-sectional view taken along line XI-XI (FIG. 10). The exposure surface PE is provided with at least one step structure having a step upper surface S1, a step lower surface S3 having a height lower than the step upper surface S1, and an inclined surface S2 connecting the step upper surface S1 and the step lower surface S3 to each other. The height difference of this step structure may exceed the DOF of the writing apparatus 100 and may be 100 μm or more. At least one writing pattern to be written in this embodiment includes at least one step pattern. The step pattern is a writing pattern that is at least partially written on the inclined surface S2 of the step and extends in the longitudinal direction in a plan view (the field of view of FIG. 10). The step pattern may be a writing pattern that crosses the inclined surface S2 between the step upper surface S1 and the step lower surface S3. In other words, the step pattern may be a drawing pattern that extends from the step upper surface S1 to the step lower surface S3 via the inclined surface S2.

[0051] <Application Examples> Fig. 12 is a partial plan view showing a semiconductor module MD1 as an example of an apparatus that requires the drawing of the above-mentioned step pattern in its manufacture. Fig. 13 is a partial cross-sectional view taken along line XIII-XIII (Fig. 12). The semiconductor module MD1 has an upper surface wiring MT formed on the upper surface of the substrate W by a photolithography process using drawing of a step pattern. The upper surface wiring MT crosses the inclined surface S2 between the step upper surface S1 and the step lower surface S3. By using the upper surface wiring MT, the semiconductor chip CP1 on the step upper surface S1 and the semiconductor chip CP3 on the step lower surface S3 can be electrically connected to each other.

[0052] Fig. 14 is a partial cross-sectional view showing a semiconductor module MD2 as a modified example of the semiconductor module MD1 (Fig. 13). In the semiconductor module MD2, a semiconductor chip CP3 is disposed on the opposite side of the stepped lower surface S3 of the substrate W. The semiconductor chip CP3 and the upper surface wiring MT are connected via a through wiring MV penetrating the substrate W and a back surface wiring MD provided on the back surface of the substrate W.

[0053] <Control unit functions> 15 is a functional block diagram showing a schematic configuration of the control unit 60 (FIG. 1). The control unit 60 has a storage unit 61, an extraction unit 62, and a rotation adjustment unit 63.

[0054] The storage unit 61 stores data representing a drawing pattern to be drawn on the substrate W. For example, as shown in the upper part of FIG. 16 (or FIG. 17), the storage unit 61 stores a drawing pattern PTX having a longitudinal direction along the substrate orientation WX in a planar view, and a drawing pattern PTY having a longitudinal direction along the substrate orientation WY in a planar view. At least one drawing pattern is the above-mentioned step pattern. At least one drawing pattern PTX may be a step pattern, and at least one drawing pattern PTY may be a step pattern, and such a case will be described below. In addition, these step patterns are also referred to as step pattern PTX and step pattern PTY using the same symbols as the drawing patterns PTX and PTY.

[0055] As shown in Fig. 16, the extraction unit 62 extracts data representing step patterns having a longitudinal direction within a first allowable angle range based on the substrate orientation WY (first substrate orientation) as first pattern data. As a result, a step pattern PTY is extracted. In the illustrated example, the first allowable angle range may be zero, but when step patterns having various longitudinal directions are mixed, the first allowable angle range may be set appropriately, and the range is, for example, within ±10 degrees.

[0056] 17, the extraction unit 62 extracts data representing step patterns having a longitudinal direction within a second allowable angle range based on the substrate orientation WX (a second substrate orientation perpendicular to the first substrate orientation) as second pattern data. As a result, a step pattern PTX is extracted. In the illustrated example, the second allowable angle range may be zero, but when step patterns having various longitudinal directions are mixed, the second allowable angle range may be set appropriately, and the range is, for example, within ±10 degrees. The second allowable angle range may be the same as the first allowable angle range.

[0057] As a modified example, the extraction unit 62 may extract, as the third pattern data, data representing step patterns having a longitudinal direction within a third allowable angle range based on a third substrate orientation, which is a substrate orientation between the substrate orientations WX and WY. The third substrate orientation may be, for example, a substrate orientation rotated 45 degrees clockwise from the substrate orientation WY. In this case, exposure scanning is also performed in a third mode in which the orientation of the substrate W is intermediate between the first mode (FIG. 8) and the second mode (FIG. 9).

[0058] The rotation adjustment unit 63 (FIG. 15) adjusts the orientation of the substrate W in the horizontal plane by controlling the rotation mechanism 21 (FIGS. 1 and 2). This adjustment is performed so that the longitudinal direction of the step pattern extracted by the extraction unit 62 and the Y direction approximately coincide with each other in a plan view (field of view in the XY plane). Specifically, in the case of FIG. 16, the adjustment is performed so that the substrate orientation WY corresponding to the longitudinal direction of the step pattern PTY approximately coincides with the Y direction. Also, in the case of FIG. 17, the adjustment is performed so that the substrate orientation WX corresponding to the longitudinal direction of the step pattern PTX approximately coincides with the Y direction. The degree of approximately coincidence corresponds to the above-mentioned allowable angle range. Here, the projection of the orthogonal direction GY (FIG. 1) of the diffraction grating 440 of the modulator 44 onto the horizontal plane (i.e., the XY plane) coincides with the Y direction. Therefore, the above adjustment is, in other words, an adjustment performed so that the longitudinal direction of the step pattern extracted by the extraction unit 62 and the orthogonal direction GY of the diffraction grating 440 approximately coincide with each other in a plan view.

[0059] <Drawing method> Next, a drawing method according to this embodiment will be illustrated in Fig. 18, which is a flow chart showing the outline of the drawing method.

[0060] Step ST10 (Fig. 1 8 ), the substrate W is held on a horizontal plane (XY plane) by a stage 10 (FIGS. 1 and 2). Data representing a pattern to be drawn is stored in a storage unit 61 (FIG. 15) of a control unit 60.

[0061] Step ST20 (Fig. 1 8 16, the pattern data corresponding to the step pattern PTY is extracted. 8 16, the orientation of the substrate W in the horizontal plane is adjusted according to the substrate orientation WY corresponding to the longitudinal direction of the step pattern PTY. As described above, this adjustment is performed so that the substrate orientation WY corresponding to the longitudinal direction of the step pattern PTY and the Y direction substantially coincide with each other in a plan view. This makes it possible to start exposure scanning in the first mode shown in FIG.

[0062] Step ST40 (FIG. 1 8 ), the light modulated by the modulator 44 is irradiated onto the substrate W by exposure scanning in the first mode (FIG. 8). As a result, a step pattern PTY is written as shown in FIG 19. In FIG 19 and in each of FIG 20 and FIG 21 described later, the upper part is an enlarged view of a rectangular portion in the lower part.

[0063] Step ST50 (Fig. 1 8 ), the pattern data corresponding to the step pattern PTX is extracted as described above with reference to FIG. 8 17, the orientation of the substrate W in the horizontal plane is adjusted according to the substrate orientation WX corresponding to the longitudinal direction of the step pattern PTX. As described above, this adjustment is performed so that the substrate orientation WX corresponding to the longitudinal direction of the step pattern PTX and the Y direction substantially coincide with each other in a plan view. Specifically, as shown by the arrow in FIG. 20, the substrate W is rotated 90 degrees. This makes it possible to start exposure scanning in the second mode shown in FIG. 9.

[0064] Step ST70 (FIG. 1 8 21, the light modulated by the modulator 44 is irradiated onto the substrate W by exposure scanning in the second mode (FIG. 9). As a result, a step pattern PTX is written as shown in FIG.

[0065] In this manner, both the step pattern PTX and the step pattern PTY are written. Writing patterns other than the step pattern PTX and the step pattern PTY may be written simultaneously in either the exposure scanning in the first mode or the exposure scanning in the second mode.

[0066] In each of the above exposure scans, the focus position of the modulated light (the focus position at the right end in the optical path shown in FIG. 6) may be fixed at a certain reference height. In that case, referring to FIG. 1, the distance in the height direction between the head unit 402 and the stage 10 is maintained constant. Referring to FIG. 11, the reference height may be the height position of the step upper surface S1 or the height position of the step lower surface S3, but is preferably a height position between these, and more preferably an intermediate height position between these. The focus position may be fixed at the above reference height even during the period when the exposure scan crosses the inclined surface S2 between the step upper surface S1 and the step lower surface S3. In other words, even during the period when the exposure scan crosses the inclined surface S2 between the step upper surface S1 and the step lower surface S3, this embodiment does not necessarily require fine adjustment of the focus position.

[0067] <Comparative Example> FIG. 22 is a partial cross-sectional view showing a schematic state of exposure scanning SC using a two-dimensional modulator such as a DMD as a first comparative example. When a width D1 is intended to be written, if the height position of the step upper surface S1 is adopted as the focus position, the desired exposure is possible on the step upper surface S1, but on the step lower surface S3, exposure with a width D3 larger than the width D1 is performed due to defocusing. As a result, the writing accuracy is reduced. Specifically, when the photosensitive layer is a negative resist layer, as shown in the partial plan view of FIG. 23, the width of the resist pattern NL is unintentionally larger on the step lower surface S3 than the desired width shown by the two-dot chain line. If it were possible to perform high-precision autofocus during the exposure scanning SC, this problem would be solved. However, such autofocus requires complex control, and when the height difference is large (especially when it is 100 μm or more), such control is difficult in practice.

[0068] FIG. 24 is a diagram for explaining a method for forming lines and spaces (L / S) of a resist pattern NL by repeatedly turning on / off pixels PX of a modulator 44 during exposure scanning SC as a second comparative example. In exposure scanning SC, adjacent pixels PX are repeatedly turned on / off collectively, so that L / S of the resist pattern NL can be formed. In this case, the exposure light amount INT has a Gaussian shape in the orthogonal direction GY corresponding to the width direction of the L / S. Furthermore, this Gaussian shape is highly dependent on defocus on the exposure surface PE (FIG. 6) as shown by the arrow in FIG. 24 for reasons similar to those of the comparative examples of FIG. 22 and FIG. 23 described above. Therefore, the width of the resist pattern NL varies greatly due to defocus.

[0069] <Effects> 25 is a diagram for explaining a method for forming lines and spaces (L / S) of a resist pattern NL by exposure scanning SC of the present embodiment. This exposure scanning SC is performed by exposing at least one pixel PX ON and at least one pixel PX OFF The exposure scanning is performed while maintaining the state in which the lines are repeatedly arranged. In this case, the exposure light amount INT has a top hat shape in the arrangement direction GX corresponding to the width direction of the L / S, as shown in the middle of FIG. 25. This top hat shape has a small dependency on defocus on the exposure surface PE (FIG. 5). Therefore, the width of the resist pattern NL is not easily affected by fluctuations caused by defocus. Therefore, as shown in FIG. 25, by adjusting the orientation of the substrate W so that the longitudinal direction of the line pattern is perpendicular to the arrangement direction GX, the pattern can be written with high accuracy even on the exposure surface PE having a height difference exceeding the DOF. At that time, there is no need to adjust the focus of the optical system in a complicated manner. Furthermore, by changing the orientation of the substrate W and performing exposure scanning SC multiple times, line patterns having different longitudinal directions can be written with high accuracy.

[0070] Figure 26 is a micrograph showing an example of the writing method described in Figure 25. The height difference between the step upper surface S1 and the step lower surface S3 was 185 μm. A line pattern of a negative resist layer was written with high precision at a constant width of 20 μm from the step upper surface S1 through the inclined surface S2 to the step lower surface S3.

[0071] 25 and 26, the drawing pattern has an L / S shape, but the shape of the drawing pattern is not limited to this. Also, although the example shows a case where a negative resist is used, a positive resist may be used instead. [Explanation of symbols]

[0072] 10: Stage 21: Rotation mechanism 40: Optical unit 42: Laser oscillator (light source) 43:Illumination optical system 44: Modulator 45: Projection optical system 46: Mirror 60: Control section 61: Storage section 62:Extraction part 63: Rotation adjustment unit 100:Drawing device 401: Light source section 402: Head section 431: Powell lens 432: Collimator lens 433: Focusing lens 440: Diffraction grating 441: Fixed ribbon 442: Movable ribbon 450: Driver circuit unit 451: Fourier transform lens 452: Fourier filter 453: Inverse Fourier transform lens GX: Array direction GY: Orthogonal direction NL: Resist pattern PE: Exposed surface PTX: Drawing pattern, step pattern PTY: Drawing pattern, step pattern PX: Pixels S1: Step top S2: Inclined surface S3: Bottom surface of step SC: Exposure scanning W: Substrate

Claims

1. 1. An imaging apparatus for imaging at least one imaging pattern on an exposure surface of a substrate, comprising: the exposure surface is provided with at least one step structure having a step upper surface, a step lower surface having a height lower 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 includes at least one step pattern that is at least partially drawn on the inclined surface of the step structure, the at least one step pattern extending in a longitudinal direction in a plan view, and the drawing apparatus: a substrate holding mechanism for holding the substrate on a horizontal surface; A light source; a modulator having a diffraction grating having a plurality of diffraction elements arranged in one direction, for modulating 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 within the horizontal plane; a control unit that controls the rotation mechanism so that an orientation of the substrate in the horizontal plane is adjusted so that the longitudinal direction of the at least one step pattern and an orthogonal direction orthogonal to the one direction of the diffraction grating are substantially aligned in a plan view; Equipped with the parallelism of the light emitted from the objective lens and directed toward the exposure surface is higher in a direction perpendicular to the longitudinal direction than in the longitudinal direction; drawing device.

2. The drawing device according to claim 1 , The imaging device further comprises an illumination optical system between the light source and the diffraction grating, the illumination optical system providing the light from the light source to the diffraction grating as parallel light in the one direction.

3. 3. The drawing device according to claim 1, The plurality of diffractive elements are arranged in only one direction.

4. 4. The drawing device according to claim 1, the control unit includes an extraction unit that extracts, as first pattern data, data representing one of the at least one step patterns having a longitudinal direction within a first allowable angle range based on a first substrate orientation of the substrate.

5. The drawing device according to claim 4, A drawing apparatus, wherein the first allowable angle range is within ±10 degrees.

6. The drawing device according to claim 4 or 5, The extraction unit extracts, as second pattern data, data representing one of the at least one step patterns having a longitudinal direction within a second allowable angle range based on a second substrate orientation of the substrate that is different from the first substrate orientation of the substrate.

7. The drawing device according to claim 6, The second substrate orientation is orthogonal to the first substrate orientation.

8. 1. A method for writing at least one writing pattern on an exposure surface on a substrate, comprising the steps of: The exposure surface is provided with at least one step structure having a step upper surface, a step lower surface having a height lower than the step upper surface, and an inclined surface connecting the step upper surface and the step lower surface, the at least one writing pattern includes at least one step pattern that is at least partially written on the inclined surface of the step structure, and the at least one step pattern extends in a longitudinal direction in a plan view, and the writing method includes: (a) holding the substrate on a horizontal surface; (b) adjusting an orientation of the substrate in the horizontal plane; (c) irradiating the exposure surface with light modulated by a modulator having a diffraction grating with a plurality of diffraction elements arranged in one direction through an objective lens; Equipped with the step (b) is performed such that the longitudinal direction of the at least one step pattern and a direction perpendicular to the one direction of the diffraction grating substantially coincide with each other in a plan view; the parallelism of the light emitted from the objective lens and directed toward the exposure surface is higher in a direction perpendicular to the longitudinal direction than in the longitudinal direction; How to draw.

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