JP2020052075A - Drawing device and drawing method - Google Patents

Abstract

To provide a drawing device performing drawing by irradiating a substrate with a convergent light beam, in which a convergent position of the light beam is properly controlled even in a case where a surface position of the substrate cannot be detected temporarily.SOLUTION: A drawing device 100 of the present invention alternately and repeatedly performs main scanning movement that moves an incident position of a light beam from one end of the substrate to the other end in a specified scanning direction and sub-scanning movement that moves the incident position of the light beam in a direction orthogonal to the scanning direction by a predetermined pitch. A history of an adjustment amount Vf given from a control unit 90 to a focus drive unit 442 for adjusting a convergent position of the light beam is stored in a storage unit 99. The adjustment amount Vf in a control command when a detection error occurs during execution of the main scanning movement is determined based on the history stored in the storage unit 99.SELECTED DRAWING: Figure 4

Description

  The present invention relates to control of a drawing apparatus for drawing by irradiating a substrate with a convergent light beam, and more particularly to control of a convergence position of a light beam.

  For example, as a method of forming a pattern on a substrate such as a semiconductor wafer or a glass substrate, there is a technique of drawing by light irradiation. In this technique, a substrate on which a photosensitive layer is formed is used as a drawing target, and light modulated based on drawing data is irradiated on the drawing target to expose the photosensitive layer. As an optical modulator for performing such light modulation, a spatial light modulation element can be suitably applied. For example, in the drawing apparatus disclosed in Patent Document 1 previously disclosed by the present applicant, a line beam light is made incident on a spatial light modulator, and a control voltage based on drawing data is applied to a movable ribbon member of the spatial light modulator. The modulated reflected light is converged by an optical system, and is incident as a converged light beam on a substrate, which is an object to be drawn, to perform drawing.

  In this conventional technique, in order to maintain the convergence position of the light beam on the substrate surface irrespective of fluctuation factors such as changes in the substrate surface height, the substrate surface position is determined from the light receiving position of the reflected light of the light incident on the substrate surface. An autofocus mechanism is provided for detecting the light beam and moving the focusing lens up and down according to the detection result so that the light beam always converges at the surface position of the substrate.

JP-A-2005-066869

  In the above-described autofocus mechanism, optical position detection temporarily functions due to a change in the light reflection direction due to a stepped portion such as a dent provided in the substrate or a foreign substance attached to the substrate. May not work. However, the above-mentioned prior art does not incorporate measures against this problem.

  The present invention has been made in view of the above problems, and in a drawing apparatus that irradiates a substrate with a convergent light beam to perform drawing, even when the substrate surface position cannot be detected temporarily, the light beam converge position is appropriately controlled. The purpose is to provide a technology that can do this.

  One embodiment of a drawing apparatus according to the present invention, in order to achieve the above object, a stage capable of placing a substrate in a horizontal position, a drawing head that irradiates a convergent light beam onto a surface of the substrate, and performs drawing. A scanning moving unit that relatively moves a stage and the drawing head to scan an incident position of the light beam on the substrate surface, and a detecting unit that optically detects a surface position of the substrate on which the light beam is incident A focus adjustment unit that adjusts the convergence position of the light beam in the optical axis direction, and a control unit that provides a control command to the focus adjustment unit that specifies an adjustment amount of the convergence position based on a detection result of the detection unit. And a storage unit for storing the history of the adjustment amount, wherein the scanning movement unit moves the incident position of the light beam from one end of the substrate to the other end along a predetermined scanning direction, and ,Previous The sub-scanning movement of moving the incident position of the light beam by a predetermined pitch in a direction orthogonal to the scanning direction is alternately and repeatedly performed, and the control unit causes the detection unit to detect a detection error during the execution of the main scanning movement. The adjustment amount in the control command at the time of is determined based on the history stored in the storage unit.

  In one aspect of the drawing method according to the present invention, the stage on which the substrate is placed in a horizontal posture and the drawing head that draws by irradiating a convergent light beam on the surface of the substrate are relatively moved to move the drawing head. A drawing method of scanning the incident position of the light beam on the substrate surface to draw on the substrate, and in order to achieve the above object, a step of optically detecting a surface position of the substrate on which the light beam is incident; and Calculating the adjustment amount of the convergence position based on the detection result of the surface position; adjusting the convergence position of the light beam in the optical axis direction according to the adjustment amount; Storing, and when the detection result of the surface position is normal, the adjustment amount is determined so that the convergence position is the same as the surface position of the substrate to be detected, while the detection of the surface position is performed. If an error occurs Is determined based on said stored history.

  In the invention configured as described above, the history of the adjustment amount of the light beam convergence position determined based on the detection result of the surface position of the substrate is stored. Therefore, even when an error occurs temporarily in the detection of the surface position, the current adjustment amount can be determined from the past control results around the current scanning position. The substrate surface has minute irregularities due to the structure of the electronic device formed on the surface and foreign substances attached to the surface, but the position fluctuation that the drawing apparatus should follow is, for example, the warpage of the substrate. It is more gradual caused by such factors. For this reason, the method of determining the current adjustment amount by analogy from the control results in the vicinity has sufficient practicality.

  As described above, according to the present invention, in a drawing apparatus that irradiates a substrate with a convergent light beam and draws, when a detection error of a surface position of the substrate occurs, based on a past control result at a peripheral position, The convergence position is adjusted by the obtained adjustment amount. Therefore, even when the surface position of the substrate cannot be detected temporarily, the convergence position of the light beam can be appropriately controlled.

FIG. 1 is a front view schematically showing a schematic configuration of a drawing apparatus according to the present invention. FIG. 3 is a diagram schematically illustrating an example of a detailed configuration of the optical head. FIG. 3 is a diagram illustrating an operation of a focus drive mechanism. FIG. 2 is a block diagram illustrating a control system of the drawing apparatus. FIG. 3 is a diagram illustrating a configuration example of a substrate that is a drawing target. FIG. 4 is a diagram illustrating a problem in focus control. FIG. 11 is a diagram illustrating a concept of obtaining a current focus adjustment amount from a past history. FIG. 4 is a principle diagram for explaining a specific method of deriving a focus adjustment amount. 5 is a flowchart illustrating a drawing operation by the drawing apparatus. 6 is a flowchart illustrating a drawing process. 9 is a flowchart illustrating a focus control process.

  FIG. 1 is a front view schematically showing a schematic configuration of a drawing apparatus according to the present invention. In order to unify the directions in the following drawings, XYZ rectangular coordinates are set as shown in FIG. Here, the XY plane is a horizontal plane, and the Z direction represents a vertical direction. More specifically, the (-Z) direction indicates a vertically downward direction. The rotation direction about the Z axis is represented by the θ axis.

  The drawing apparatus 100 is an apparatus that irradiates light to the upper surface of a substrate W on which a layer of a photosensitive material such as a resist is formed to draw a pattern. Note that as the substrate W, various substrates such as a semiconductor substrate, a printed substrate, a substrate for a color filter, a glass substrate for a flat panel display provided in a liquid crystal display device or a plasma display device, and a substrate for an optical disk can be applied. In the illustrated example, the upper layer pattern is drawn so as to overlap the lower layer pattern formed on the upper surface of the circular semiconductor substrate.

  The drawing apparatus 100 includes: a main body formed by attaching a cover panel (not shown) to a ceiling surface and a peripheral surface of a skeleton configured by the main body frame 101; It has a configuration in which various components are arranged.

  The inside of the main body of the drawing apparatus 100 is divided into a processing area 102 and a transfer area 103. In the processing area 102 among these areas, the stage 10, the stage moving mechanism 20, the optical unit U, and the alignment unit 60 are mainly arranged. On the other hand, the transfer area 103 is provided with a transfer device 70 such as a transfer robot for transferring the substrate W into and out of the processing area 102.

  An illumination unit 61 that supplies illumination light to the alignment unit 60 is arranged outside the main body of the drawing apparatus 100. In addition, the main body is provided with a control unit 90 that is electrically connected to each unit included in the drawing apparatus 100 and controls the operation of each unit.

  A cassette mounting portion 104 for mounting the cassette C is disposed outside the main body of the drawing apparatus 100 and at a position adjacent to the transfer area 103. Further, the transfer device 70 corresponding to the cassette mounting portion 104 and arranged in the transfer area 103 inside the main body takes out the unprocessed substrate W stored in the cassette C mounted on the cassette mounting portion 104 and removes the unprocessed substrate W. The substrate W is loaded (loaded) into the processing area 102, and the processed substrate W is unloaded (loaded) from the processing area 102 and stored in the cassette C. The delivery of the cassette C to the cassette mounting portion 104 is performed by an external transport device (not shown). The loading processing of the unprocessed substrate W and the unloading processing of the processed substrate W are performed by the operation of the transfer device 70 in accordance with an instruction from the control unit 90.

  The stage 10 has a flat outer shape, and is a holding unit that mounts and holds the substrate W on its upper surface in a horizontal posture. A plurality of suction holes (not shown) are formed on the upper surface of the stage 10. By applying a negative pressure (suction pressure) to the suction holes, the substrate W placed on the stage 10 is moved to the stage 10. And can be fixedly held on the upper surface of the device. Then, the stage 10 is moved by the stage moving mechanism 20.

  The stage moving mechanism 20 is a mechanism that moves the stage 10 in the main scanning direction (Y-axis direction), the sub-scanning direction (X-axis direction), and the rotation direction (rotation direction around the Z-axis (θ-axis direction)). The stage moving mechanism 20 includes a base plate 24 that supports a support plate 22 that rotatably supports the stage 10, a sub-scanning mechanism 23 that moves the support plate 22 in the sub-scanning direction, and a main that moves the base plate 24 in the main scanning direction. A scanning mechanism 25. The sub-scanning mechanism 23 and the main scanning mechanism 25 move the stage 10 according to an instruction from the control unit 90.

  The alignment unit 60 images an alignment mark (not shown) formed on the upper surface of the substrate W. The alignment unit 60 includes an alignment camera 601 having a lens barrel, an objective lens, and a CCD image sensor. The CCD image sensor included in the alignment camera 601 is configured by, for example, an area image sensor (two-dimensional image sensor). The alignment unit 60 is supported by a lifting mechanism (not shown) so as to be able to move up and down within a predetermined range.

  The illumination unit 61 is connected to the lens barrel via a fiber 611, and supplies illumination light to the alignment unit 60. The light guided by the fiber 611 extending from the illumination unit 61 is guided to the upper surface of the substrate W via the lens barrel of the alignment camera 601, and the reflected light is received by the CCD image sensor via the objective lens. As a result, the upper surface of the substrate W is imaged, and image data is obtained. The alignment camera 601 is electrically connected to the image processing unit of the control unit 90, acquires imaging data in response to an instruction from the control unit 90, and transmits the acquired imaging data to the control unit 90.

  The control unit 90 performs alignment processing for detecting a reference mark provided at a reference position of the substrate W based on image data supplied from the alignment camera 601 and positioning the optical unit U and the substrate W relative to each other. Then, pattern writing is performed by irradiating a predetermined position on the substrate W with laser light modulated according to the writing pattern from the optical unit U.

  The optical unit U has a schematic configuration in which two optical heads 4 that modulate laser light based on strip data corresponding to a drawing pattern are arranged along the X-axis direction. The number of optical heads 4 is not limited to this. Since these optical heads 4 have the same configuration as each other, the configuration related to one optical head 4 will be described below.

  The optical unit U is provided with a light irradiation unit 5 that irradiates the optical head 4 with laser light. The light irradiation unit 5 includes a laser driving unit 51, a laser oscillator 52, and an illumination optical system 53. Then, the laser light emitted from the laser oscillator 52 by the operation of the laser driving unit 51 is applied to the optical head 4 via the illumination optical system 53. The optical head 4 modulates the laser light emitted from the light irradiating unit 5 with a spatial light modulator, and falls on the substrate W moving directly below the optical head 4. As a result, the upper layer pattern (drawing pattern) is overlaid on the lower layer pattern formed on the unprocessed substrate W and exposed.

  FIG. 2 is a diagram schematically illustrating an example of a detailed configuration of the optical head. As shown in FIG. 2, the optical head 4 includes a spatial light modulator 41 having a diffractive optical element 410. Specifically, the spatial light modulator 41 attached to the upper part of the column 400 extending in the vertical direction (Z direction) on the optical head 4, with the reflecting surface of the diffractive optical element 410 facing downward, It is supported by a support 400 via a movable stage 414.

  In the optical head 4, the diffractive optical element 410 is arranged such that the normal to the reflection surface thereof is inclined with respect to the optical axis OA, and the light emitted from the illumination optical system 53 passes through the opening of the support column 400 to the mirror 42. After being reflected by the mirror 42 and irradiating the diffractive optical element 410. Then, the state of each channel of the diffractive optical element 410 is switched by the control unit 90 according to the drawing data, and the laser light incident on the diffractive optical element 410 is modulated.

  The laser beam reflected from the diffractive optical element 410 as the 0th-order diffracted light enters the lens of the projection optical system 43, while the laser light reflected from the diffractive optical element 410 as the first or higher-order diffracted light is projected onto the projection optical system 43. No light enters the 43 lens. That is, basically, only the zero-order diffracted light reflected by the diffractive optical element 410 is incident on the projection optical system 43.

  The light that has passed through the lens of the projection optical system 43 is converged by the focusing lens 441 and is guided as a converged light beam onto the substrate W at a predetermined magnification. The focusing lens 441 is attached to a focus drive mechanism 442. The focus driving mechanism 442 raises and lowers the focusing lens 441 in the vertical direction (Z-axis direction) in response to a control command from the control unit 90, so that the convergence position of the light beam emitted from the focusing lens 441 is shifted to the substrate. It is adjusted to the upper surface Ws of W.

  An irradiator 451 and a light receiver 452 functioning as an autofocus mechanism 45 are provided below the housing of the optical head 4. The irradiating unit 451 irradiates the light emitted from a light source constituted by a laser diode (LD) obliquely to the upper surface Ws of the substrate W. The light receiving unit 452 includes a solid-state imaging device such as a complementary metal oxide semiconductor (CMOS) sensor or a charge coupled device (CCD) sensor, and detects light reflected from the upper surface Ws of the substrate W. Then, the control unit 90 detects the position of the substrate upper surface W in the Z direction, that is, the distance between the optical head 4 and the substrate upper surface Ws from the detection result of the light receiving unit 452.

  That is, when the upper surface Ws of the substrate moves away from the optical head 4 as shown by the solid arrow in the drawing, or when the upper surface Ws of the substrate approaches the optical head 4 as shown by the broken arrow, the optical path of the reflected light from the upper surface Ws of the substrate Changes in the directions indicated by the solid arrow and the broken arrow, respectively, and the amount of light received at each light receiving position of the light receiving unit 452 also changes. Therefore, the peak position of the amount of received light in the light receiving unit 452 changes as indicated by the solid arrow and the broken arrow, respectively. The control unit 90 detects the distance between the optical head 4 and the upper surface Ws of the substrate by using this. Then, the control unit 90 operates the focus driving mechanism 442 according to the detection distance to move the focusing lens 441 up and down so that the focus of the focusing lens 441 is adjusted to the upper surface Ws of the substrate and the convergence position of the laser light is adjusted to the substrate. Adjust accurately to the upper surface Ws (auto focus).

  FIG. 3 is a diagram showing the operation of the focus drive mechanism. As shown in FIG. 3A, the focus driving mechanism 442 moves the focusing lens 441 up and down in the Z direction according to a control command including the focus adjustment amount Vf given from the control unit 90. For example, even if the Z-direction position Zs of the substrate upper surface Ws fluctuates due to the warpage of the substrate W, the focus driving mechanism 442 changes the Z-direction position Zf of the focusing lens 441 so as to follow the Z-direction. The FP is adjusted so that it is always on the substrate upper surface Ws.

  As shown in FIG. 3B, the Z direction position Zf of the focusing lens 441 is determined by a focus adjustment amount Vf given from the control unit 90 to the focus driving mechanism 442. In other words, by giving a control command including the focus adjustment amount Vf from the control unit 90 to the focus drive mechanism 442, the focusing lens 441 is positioned at the Z-direction position Zf according to the focus adjustment amount Vf. In this example, the Z direction position Zf of the focusing lens 441 changes linearly with respect to the focus adjustment amount Vf. Note that if the focus adjustment amount Vf and the Z direction position Zf of the focusing lens 441 have a one-to-one relationship, the relationship does not necessarily have to be linear.

  FIG. 4 is a block diagram showing a control system of the drawing apparatus. In the control unit 90, the following functional blocks 91 to 96 are realized by a CPU (not shown) executing a control program stored in the storage unit 99 in advance or by dedicated hardware. The illumination control unit 91 controls the light irradiation unit 5 of the optical unit U to emit a light beam. The drawing control unit 92 controls the driver 921 based on the drawing recipe stored in the storage unit 99, applies a control voltage from the driver 921 to the diffractive optical element 410, and modulates the light beam according to the pattern to be drawn. I do.

  The focus control unit 95 controls an autofocus operation. Specifically, the focus control unit 95 detects the position of the substrate upper surface Ws based on the output from the light receiving unit 452 of the autofocus mechanism 45, and based on the result, adjusts the focal point FP of the convergent light beam to the substrate upper surface Ws. Is calculated and transmitted to the focus drive mechanism 442. The stage control unit 94 controls the stage moving mechanism 20 to move the stage 10 relative to the optical head 4. The alignment control unit 93 executes an alignment process based on image data output from the alignment camera 601 of the alignment unit 60.

  The beam incident position control section 96 is provided on the side of the stage 10 and controls the movable stage 414 of the spatial light modulator 41 based on an output signal from the observation optical system 80 that measures the incident direction of the light beam from the optical head 4. Is operated to execute the incident position adjustment processing for optimizing the position of the line beam light incident on the diffractive optical element 410 as necessary. It is to be noted that, for a specific method of the incident position adjustment processing, the auto focus adjustment, the alignment adjustment, and the like, for example, the method described in Patent Document 1 can be applied.

  Next, the operation of the drawing apparatus 100 configured as described above will be described. As described above, the drawing apparatus 100 can perform drawing by exposure on various substrates. Here, as an example, a drawing operation when drawing on a semiconductor substrate in which a plurality of semiconductor device regions are arranged in a two-dimensional matrix on a substantially circular substrate will be described.

  FIG. 5 is a diagram showing a configuration example of a substrate as a drawing target. As shown in FIG. 5A, the substrate W has a substantially circular outer shape, and a plurality of device regions R each having a substantially rectangular shape are arranged in a two-dimensional matrix on the upper surface Ws. The drawing apparatus 100 performs drawing in each device region R with a predetermined drawing pattern as a part of a manufacturing process for manufacturing a semiconductor device in each device region R. The pattern drawn in each device region R is the same, so that the drawing apparatus 100 draws a drawing pattern according to drawing data given in advance in each device region R in order. At this time, the drawing position of the upper surface Ws of the substrate by the optical head 4 is sequentially changed by relatively horizontally moving the substrate W mounted on the stage 10 and the optical head 4, that is, by performing scanning movement.

  FIG. 5B is a diagram illustrating an example of the path of the scanning movement. Here, the relative movement between the substrate W and the optical head 4 will be described assuming that the drawing position at which light from the optical head 4 is incident on the substrate W moves relative to the substrate W. The scanning movement is realized by moving the stage 10 on which the substrate W is mounted in the XY directions. As shown by the dotted arrow in the drawing, in this drawing operation, the drawing position first moves in the (+ Y) direction with the position corresponding to the lower left of the substrate W as the drawing start position Ps in the drawing. When the drawing position advances to the upper left end of the substrate W, the drawing position moves by a predetermined pitch Px in the (+ X) direction. Next, when the moving direction is reversed to the (−Y) direction and reaches the lower end in the drawing of the substrate W, that is, the (−Y) side end, the drawing position is moved again by the predetermined pitch Px in the (+ X) direction. Then, the movement in the (+ X) direction is performed again.

  As described above, the relative movement between the substrate W and the optical head 4 is obtained by alternately combining the scanning movement in the (+ Y) direction or the (-Y) direction and the pitch feed movement in the (+ X) direction. ing. Finally, when the drawing position reaches the position corresponding to the lower right of the substrate W, the scanning movement ends. Hereinafter, the movement of the drawing position in the Y direction is referred to as “main scanning direction”, and the Y direction is referred to as “main scanning direction”. The pitch feed of the drawing position in the X direction is referred to as “sub-scanning movement”, and the X direction is referred to as “sub-scanning direction”.

  FIG. 6 is a diagram illustrating a problem in focus control. During the execution of the scanning movement for drawing as described above, the convergence position of the light beam needs to be constantly adjusted to the substrate upper surface Ws. However, as shown in FIG. 6A, the position of the substrate upper surface Ws changes in the Z direction due to, for example, the warpage of the substrate W. Therefore, the converging position of the converging light beam also needs to be moved up and down in conjunction with the fluctuation of the substrate upper surface Ws.

  Although the autofocus operation of the drawing apparatus 100 can respond to such a demand, the autofocus operation may temporarily lose its function. For example, as shown in FIG. 6B, the foreign matter A adheres to the upper surface Ws of the substrate, and thereby the light emitted from the irradiation unit 451 of the autofocus mechanism 45 to the upper surface Ws of the substrate is blocked or the reflection direction is changed. As a result, the light receiving unit 452 may not receive light correctly. Further, as shown in FIG. 6C, an optical path from the irradiation unit 451 to the light receiving unit 452 via the substrate upper surface Ws may be blocked by a step such as a depression B provided on the upper surface of the substrate.

  If the light incident on the light receiving unit 452 is blocked or scattered for such a reason, the position of the substrate upper surface Ws cannot be detected by the autofocus mechanism 45, and as a result, the autofocus operation does not function. The drawing apparatus 100 of the present embodiment addresses this problem as follows. To make this possible, when the light receiving unit 452 cannot receive the reflected light from the substrate W or when there is a sudden change in the light receiving position exceeding a predetermined change amount, a detection error of the auto focus mechanism 45 is detected. Will be treated as

  As shown in FIG. 6A, the position fluctuation of the substrate upper surface Ws in the Z direction due to the warp or the like of the substrate W is relatively slow, for example, as compared with the horizontal and vertical resolutions in the focus adjustment operation. . Therefore, it is considered that it is not necessary to change the convergence position of the light beam abruptly in the normal operation. In other words, the convergence position of the light beam at a certain drawing position is not much different from the convergence position at a peripheral position. Therefore, if a history related to the adjustment of the convergence position at the peripheral position is recorded, it is possible to estimate the convergence position of the light beam at the current drawing position to some extent from the information recorded in the history.

  In the present embodiment, based on this principle, focus adjustment is performed when a detection error of the autofocus mechanism 45 occurs. Specifically, the focus adjustment amount Vf given from the control unit 90 to the focus driving mechanism 442 for setting the convergence position of the light beam is stored in the storage unit 99 for a certain period. Then, when a detection error occurs in the substrate position detection, the current focus adjustment amount Vf is derived based on the history of the focus adjustment amount Vf stored in the storage unit 99.

  FIG. 7 is a diagram exemplifying the concept when calculating the current focus adjustment amount from the past history. As shown by the dotted arrow in the drawing, the drawing position reciprocates in the Y direction, which is the main scanning direction, while changing the X direction position at a constant pitch Px with respect to the substrate upper surface Ws. Therefore, in the X direction, scanning on the substrate W proceeds in the (+ X) direction. The scanning direction in the Y direction is the (+ Y) direction when the drawing position moves in the (+ Y) direction, and is the (-Y) direction when the drawing position moves in the (-Y) direction. The focus adjustment amount Vf at the current position Pe can be determined using the set value of the focus adjustment amount Vf on the rear side (upstream side) with respect to the current drawing position Pe in the traveling direction of such a scanning movement. It is.

  For example, as shown by an arrow Ay in FIG. 7, when determining the current focus adjustment amount Vf from the history along the Y direction, the change of the focus adjustment amount Vf up to the current position Pe in the current main scanning movement. Can be used as a history. That is, assuming that the change in the focus adjustment amount Vf up to the present will continue in the future, the current focus adjustment amount Vf can be adjusted by extrapolation from the change in the focus adjustment amount Vf.

  Further, as indicated by an arrow Ax in FIG. 7, a method of determining the current focus adjustment amount Vf from the history along the X direction can be as follows. The actual focus adjustment amount Vf at the same position as the current drawing position Pe in the Y direction, which is the main scanning direction, and at the position (−X) side of the current drawing position Pe in the X direction, which is the sub-scanning direction. Based on this, the current adjustment amount Vf can be obtained by estimation. Drawing at these positions has already been completed. If the focus adjustment amount Vf applied at the time of drawing is stored in the storage unit 99, this can be read out to obtain the current focus adjustment amount Vf.

  FIG. 8 is a principle diagram for explaining a specific method of deriving the focus adjustment amount. FIG. 8A is an example of a method using the history in the Y direction. In the scanning movement in the Y direction, which is the main scanning direction, the Z direction position of the substrate upper surface Ws is detected at a constant control cycle, and the focus adjustment amount Vf is determined based on the detected position. Accordingly, as shown by the solid line in FIG. 8A, in the Y direction, the focus adjustment amount Vf is sequentially updated at a constant pitch Py corresponding to the scanning movement amount in one control cycle, and the focusing lens 411 is accordingly updated. Is periodically changed.

  If a detection error of the autofocus mechanism 45 occurs at a position indicated by a circle in the drawing, thereafter, it becomes impossible to calculate the focus adjustment amount Vf based on the position detection result. Therefore, as shown by the dotted line, the focus adjustment amount Vf is determined so that the increase or decrease of the focus adjustment amount Vf up to immediately before is directly extended.

  FIG. 8B is a diagram illustrating an example of a method using the history in the X direction. Specifically, the focus adjustment amount Vf when the drawing position in the Y direction is the same as the current position Pe is indicated by X in FIG. It is the figure plotted with respect to a direction position. Since the pitch feed at the predetermined pitch Px is performed in the X direction, the change pitch of the focus adjustment amount Vf is the same as this pitch Px. Also in this case, assuming that a detection error occurs at the position indicated by the circle, in the subsequent main scanning movement, the focus adjustment amount Vf in the previous main scanning movement in which the Y direction position is the same as the current position Pe The focus adjustment amount Vf in the subsequent scanning movement is determined so as to maintain the change indicated by.

  With this configuration, the variation of the position in the Z direction of the substrate upper surface Ws with respect to the variation factor of a relatively low frequency component such as the warpage of the substrate W is inferred from the results of past changes, and is followed. By moving the focusing lens 441 up and down, the convergence position of the light beam can be maintained on the substrate upper surface Ws.

  Further, the current focus adjustment amount Vf may be determined based on the history in the X direction and the history in the Y direction. That is, the current focus adjustment amount Vf may be derived by performing an appropriate calculation on the focus adjustment amounts obtained from the histories in the X direction and the Y direction, respectively. From the viewpoint of reflecting the history in the X direction and the history in the Y direction, the following method is also possible.

  The method is that the focus adjustment amount Vf after the occurrence of the detection error has the same change as the change of the focus adjustment amount Vf in the previous main scanning movement, as shown in FIG. 8C. In FIG. 8C, a polygonal line A represents the transition of the focus adjustment amount Vf in the current main scanning movement, and a polygonal line B represents the previous main scanning movement, that is, the pitch Px from the current X direction position (−X). This represents the transition of the focus adjustment amount Vf in the main scanning movement at the position on the direction side. As shown in the figure, the set values of the focus adjustment amounts Vf in two adjacent main scanning movements are not completely the same, but show relatively similar changes. Therefore, even after the detection error indicated by the circle, the focus adjustment amount Vf is determined to be the same as the change of the focus adjustment amount Vf in the previous main scanning movement.

  At this time, before the detection error occurs, it is assumed that the result of the focus control in the current main scanning movement is correct. That is, the value of the focus adjustment amount Vf at that time is used as it is as a fixed value, and thereafter, the focus adjustment amount Vf is applied by using not the absolute value of the focus adjustment amount Vf in the previous main scanning movement but the change. decide. Even in this case, the current focus adjustment amount Vf is determined using both the histories in the X direction and the Y direction. Therefore, although the focus adjustment amount in the previous main scanning movement is not always the same value, the change is equal.

  In the embodiment in which the main scanning movement in the (+ Y) direction and the main scanning movement in the (−Y) direction are alternately performed as in the present embodiment, the value of the focus adjustment amount Vf obtained in time series It should be noted that the arrangement of indicates the change of the focus adjustment amount Vf in the spatially opposite direction.

  Hereinafter, specific contents of the drawing operation by the drawing apparatus 100 of the present embodiment incorporating the focus control based on the above principle will be described. This drawing operation is realized by the control unit 90 executing a control program prepared in advance and causing each unit of the apparatus to execute a predetermined operation.

  FIG. 9 is a flowchart showing a drawing operation by this drawing apparatus. In the drawing operation, first, a drawing recipe representing the contents to be drawn is obtained (step S101), and an unprocessed substrate W to be drawn is loaded from the cassette C to the stage 10 (step S102). The drawing recipe is stored in the storage unit 99. Next, an alignment process is performed by the alignment unit 60 to adjust the relative position between the substrate W and the optical head 4 (Step S103). Thereby, the pattern drawing position on the substrate W is precisely adjusted.

  Then, the drawing control unit 92 prepares drawing data based on the drawing recipe (step S104). The drawing data is supplied to the spatial light modulator 41 of the optical head 4 to irradiate the substrate W while modulating the light beam, thereby forming a pattern. Is performed (step S105). When the drawing processing is completed, the processed substrate W is unloaded from the stage 10 and stored in the cassette C (Step S106). By repeating the above-described processing as needed, it is possible to sequentially draw on the plurality of substrates W.

  FIG. 10 is a flowchart showing the drawing process. First, each unit of the apparatus is initialized to a predetermined initial state (step S201). Subsequently, focus control by the autofocus mechanism 45 and scanning movement of the substrate W in the Y direction by the stage moving mechanism 20 are started (step S202). Details of the focus control processing will be described later.

  The scanning movement at this point is a preliminary scanning called a pre-scan without irradiation of a light beam from the optical head 4 (step S203). In the prescan, the stage 10 is not moved in the X direction, but is scanned and moved from one end to the other end of the substrate W in the Y direction. At this time, by executing the focus control operation by the autofocus mechanism 45, basic information for adjusting the convergence position of the light beam to the substrate upper surface Ws from the initial stage of drawing is obtained.

  For this purpose, it is desirable that the prescan be performed at the same position as the position where the first main scanning movement is performed in the actual drawing. By doing so, not only can the above information be obtained, but also the amount of relative movement between the substrate W and the optical head 4 during the period from pre-scan to main scan movement for drawing is minimized, and processing time is shortened. It is also possible.

  After the end of the prescan, the optical head 4 with respect to the substrate W is positioned at a predetermined drawing start position (step S204). For example, the position Ps shown in FIG. 5B can be set as the drawing start position. If the drawing start position is the same as the position of the optical head 4 at the end of the prescan, there is no need to move between the optical head 4 and the stage 10 after the end of the prescan.

  When the optical head 4 is positioned at the drawing start position with respect to the substrate W on the stage 10, drawing starts (step S205). That is, by irradiating the substrate W with light from the optical head 4 while performing focus control and main scanning movement in the (+ Y) direction, drawing is performed on the upper surface Ws of the substrate. When the drawing position reaches the main scanning end position in the Y direction in the first main scanning movement (step S206), the drawing position is moved by one step in the X direction, more specifically, by the feed pitch Px in the (+ X) direction. (Step S208), the main scanning movement direction is reversed in the (-X) direction (Step S209). Thereby, the second main scanning movement is started. By repeating the above until the sub-scanning end position corresponding to the end of the substrate W in the (+ X) direction is reached (step S207), the drawing is completed for the entire device region R of the substrate W.

  When the drawing ends, the emission of the light beam from the optical head 4 ends (step S211), and the focus control and the scanning movement end (step S212). Then, an end operation for shifting each unit of the apparatus to a predetermined end state is executed (step S213), and the drawing process for one substrate W ends.

  FIG. 11 is a flowchart showing the focus control process. This processing is periodically executed every time a predetermined adjustment timing comes while the drawing apparatus 100 executes the drawing processing. When the adjustment timing comes (step S301), the current position of the substrate upper surface Ws in the Z direction is acquired based on the light reception result from the light receiving unit 452 of the autofocus mechanism 45 (step S302). When the detection result at this time is a normal value, that is, when the detection error condition is not satisfied (YES in step S303), the convergence position of the light beam is adjusted to the position based on the obtained detection result of the substrate upper surface position. The required focus adjustment amount Vf is obtained (step S304).

  On the other hand, if the detection result is not in the range of the normal value (NO in step S303), the focus adjustment amount Vf is obtained as a detection error based on the past control results (step S305). Any of the above-described methods can be applied as a specific method of obtaining the information. In the first main scanning movement executed at the position on the most (-X) side, the result of the prescan can be used as equivalent to the "previous main scanning movement".

  The focus adjustment amount Vf thus obtained is stored in the storage unit 99 in association with the application position (step S306). Further, focus adjustment based on the focus adjustment amount Vf is performed (step S307). Specifically, a control command including the obtained focus adjustment amount Vf is given from the focus control unit 95 of the control unit 90 to the focus drive mechanism 442, and the Z-direction position Zf of the focusing lens 441 is adjusted accordingly. Thereby, focus adjustment is performed.

  By performing the above-described processing at each predetermined adjustment timing, focus adjustment is performed at a constant control cycle. The control cycle can be, for example, 1 [msec] to 10 [msec]. Thereby, the convergence position of the light beam can be stably adjusted to the substrate upper surface Ws. For this reason, drawing can be performed on the substrate upper surface Ws with excellent resolution. Even when the autofocus mechanism 45 cannot properly detect the position of the upper surface Ws of the substrate and a detection error occurs, the past control results near the current drawing position are read from the storage unit 99, and the focus adjustment estimated therefrom is performed. By applying the amount Vf, the convergence position of the light beam is prevented from being largely separated from the substrate upper surface Ws.

  In this focus control processing, a conditional branch is performed in each control cycle based on the presence or absence of a detection error. Therefore, even after the autofocus mechanism 45 has once detected an error, if the position can be normally detected again, the detection is performed. Focus control based on the result will be resumed. For this reason, it can be said that it has excellent resistance to temporary detection errors.

  As described above, in the drawing apparatus 100 of this embodiment, the substrate W corresponds to the “substrate” of the present invention, and the substrate upper surface Ws corresponds to the “substrate surface” of the present invention. The stage 10 functions as the “stage” of the present invention. The optical head 4 functions as the “drawing head” of the present invention, while the stage moving mechanism 20 functions as the “scan moving unit” of the present invention. In addition, the autofocus mechanism 45 functions as a “detector” of the present invention, while the focus drive mechanism 442 functions as a “focus adjuster” of the present invention. Further, the control unit 90, particularly, the focus control unit 95 functions as the “control unit” of the present invention. Further, the storage unit 99 functions as a “storage unit” of the present invention. Further, the main scanning direction (Y direction) of the present embodiment corresponds to the “scanning direction” of the present invention. Further, the pre-scan in the present embodiment corresponds to “preliminary scan movement” of the present invention.

  The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention. For example, the above-described embodiment is a drawing apparatus using the diffractive optical element 410 as a light beam modulating unit, but the modulation method is not limited to this, and the present invention is applied to an apparatus that performs drawing with an arbitrary modulation method. It is possible to

  Further, in the above embodiment, light is incident on the substrate upper surface Ws from an oblique direction, and the position of the substrate surface is detected from the result of receiving the specularly reflected light. However, the “detection unit” of the present invention is not limited to such a principle, and various mechanisms for acquiring the position of the substrate surface by an optical method can be used.

  In the focus control of the above embodiment, the focus adjustment amount Vf given to the focus drive mechanism 442 is obtained. Instead, for example, a configuration may be used in which an increment or decrement from the current focus position is calculated and provided to the focus drive mechanism.

  Furthermore, the application target of the present invention is not limited to an apparatus that irradiates a semiconductor substrate W such as a wafer as a “drawing target object” of the present invention by irradiating the substrate with light and drawing, for example, a printed wiring board or Various objects such as a glass substrate can be used as an object to be drawn.

  As described above, in the present invention, the history of the adjustment amount in the main scanning movement and the position in the scanning direction in the past main scanning movement are equal to the current scanning position in the present invention, as described above with reference to the specific embodiments. The current adjustment amount can be determined based on at least one of the adjustment amounts at the position. According to such a configuration, the current adjustment amount is determined based on the transition of the past adjustment amount in the scanning direction and the past adjustment amount in the direction orthogonal to the scanning direction. Therefore, it is suitable for causing the convergence position of the light beam to follow a gradual change in the surface position of the substrate.

  Further, the change in the adjustment amount in the scanning direction in the main scanning movement after the detection error and the change in the adjustment amount in the scanning direction in the previous main scanning movement are the same between corresponding positions in the scanning direction. , The current adjustment amount is determined. According to such a configuration, when the change in the surface position of the substrate in the scanning direction does not have a large difference between the previous main scanning movement and the current main scanning movement, the change in the surface position of the substrate is affected by light. It is possible to follow the convergence position of the beam.

  Prior to the execution of the first main scanning movement, a pre-scanning movement for acquiring information on the surface position of the substrate is performed while relatively moving the stage and the drawing head in the scanning movement direction. The adjustment amount in one main scanning movement may be determined based on the history of the preliminary scanning movement stored in the storage unit. According to such a configuration, it is possible to prepare information that can be used when a detection error occurs even in the first main scanning movement in which the result of the past main scanning movement is not accumulated.

  Further, when the detection result of the detection unit is normal, the configuration may be such that the adjustment amount is determined so that the convergence position is the same as the surface position of the substrate detected by the detection unit. According to such a configuration, as long as the surface position is properly detected, it is possible to perform drawing while stably converging the light beam on the surface of the substrate.

  INDUSTRIAL APPLICABILITY The present invention can be suitably applied to a technique for performing drawing by irradiating modulated light onto a drawing target, and in particular, performing a drawing by modulating line beam light using a diffractive optical element. It is suitable for.

4 Optical head (drawing head)
10 stage 20 stage moving mechanism (scan moving section)
45 Auto focus mechanism (detection unit)
90 control unit 95 focus control unit (control unit)
99 storage unit 100 drawing device 441 focusing lens 442 focus drive mechanism (focus adjustment unit)
Vf Focus adjustment amount (adjustment amount)
W substrate Ws Upper surface of substrate (substrate surface)

Claims (7)

A stage on which the substrate can be placed in a horizontal position,
A drawing head for drawing by irradiating a convergent light beam on the surface of the substrate,
A scanning moving unit that relatively moves the stage and the drawing head to scan an incident position of the light beam on the substrate surface;
A detection unit that optically detects the surface position of the substrate on which the light beam is incident,
A focus adjustment unit that adjusts the convergence position of the light beam in the optical axis direction,
A control unit that gives a control command to the focus adjustment unit to specify an adjustment amount of the convergence position based on a detection result of the detection unit;
A storage unit for storing a history of the adjustment amount,
A main scanning movement for moving an incident position of the light beam from one end to the other end of the substrate along a predetermined scanning direction; and a direction orthogonal to the scanning direction. And alternately repeat the sub-scanning movement to move by a predetermined pitch to
The drawing device, wherein the control unit determines the adjustment amount in the control command when the detection unit detects a detection error during execution of the main scanning movement based on a history stored in the storage unit.   The drawing apparatus according to claim 1, wherein the control unit determines the current adjustment amount based on a history of the adjustment amount in the main scanning movement.   3. The drawing apparatus according to claim 1, wherein the control unit determines the current adjustment amount based on the adjustment amount at a position where the position in the scanning direction is equal to the current scanning position in the past main scanning movement. 4. .   The control unit is configured such that a change in the adjustment amount in the scanning direction in the main scanning movement after the detection error and a change in the adjustment amount in the scanning direction in the previous main scanning movement are mutually different in the scanning direction. 4. The drawing apparatus according to claim 1, wherein the current adjustment amount is determined so as to be the same between corresponding positions. The scanning movement unit is configured to acquire information on a surface position of the substrate while relatively moving the stage and the drawing head in the scanning movement direction before performing the first main scanning movement. Execute the preliminary scanning movement of
The drawing apparatus according to claim 1, wherein the control unit determines the adjustment amount in the first main scanning movement based on a history of the preliminary scanning movement stored in the storage unit. When the detection result of the detection unit is normal,
The drawing apparatus according to claim 1, wherein the control unit determines the adjustment amount such that the convergence position is equal to a surface position of the substrate detected by the detection unit. The stage in which the substrate is placed in a horizontal position, and a drawing head that irradiates a convergent light beam onto the surface of the substrate and draws the image relative to each other to scan the incident position of the light beam on the substrate surface and scan the position. In a drawing method for drawing on a substrate,
Optically detecting the surface position of the substrate on which the light beam is incident,
A step of obtaining an adjustment amount of the convergence position based on the detection result of the surface position;
Adjusting the convergence position of the light beam in the optical axis direction according to the adjustment amount;
Storing a history of the adjustment amount,
While the detection result of the surface position is normal, while determining the adjustment amount so that the convergence position is the same as the surface position of the substrate to be detected,
A drawing method for determining based on the stored history when a detection error of the surface position occurs.

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