Exposure method and exposure apparatus

Abstract

To improve a tact time of an exposure treatment by making it possible to expose during acceleration and deceleration in a relative movement between an exposure part and a substrate holding part.SOLUTION: The exposure method and exposure apparatus according to the present invention scan an incident position of the output light beam on a substrate by relatively moving an exposure part that outputs the light beam and a substrate holding part that holds the substrate, and based on the generated signal accompanying the relative movement, the relative movement speed between the exposure part and the substrate holding part is determined, and the light beam is made incident on the substrate to perform exposure while changing the light intensity of the light beam in multiple stages at a predetermined control cycle. The control period and the maximum amount of light beam are changed according to the determined relative movement speed.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a technology for exposing a substrate by making a modulated light beam incident on substrates such as semiconductor substrates, semiconductor package substrates, printed wiring boards, and glass substrates. Background Art

[0002] As a technology for forming patterns such as wiring patterns on various substrates including semiconductor substrates, semiconductor package substrates, printed wiring boards, and glass substrates, there is a technology in which a light beam modulated according to exposure data is incident on a photosensitive layer formed on the substrate surface to expose the photosensitive layer. For example, the drawing apparatus described in Patent Document 1 is an apparatus that draws a pattern by exposing the surface of a substrate on which a photosensitive layer is formed with a modulated light beam.

[0003] In this technology, when a substrate holding portion (stage) that holds the substrate moves relative to the exposure unit in the main scanning direction (main scanning movement), exposure is performed by the modulated light beam being incident on the substrate. Then, after moving the stage by a predetermined pitch in the sub-scanning direction orthogonal to the main scanning direction (sub-scanning movement), main scanning movement and exposure are further performed. In this way, the entire surface of the substrate is exposed by alternately repeating main scanning movement involving exposure and sub-scanning movement. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2022-097979 Summary of the Invention Problems to be Solved by the Invention

[0005] In this type of exposure apparatus, exposure is performed during the period when the movement speed is constant during the main scanning movement, in order to accurately expose the substrate surface with the desired pattern. In other words, exposure is not performed during the period from when the movement is stopped until it reaches a constant speed, and during the period from when it reaches a constant speed until it stops moving again. This is a constraint on improving the cycle time of the exposure process. In particular, when exposure is performed by repeatedly performing main scanning movements and sub-scanning movements as described above, an acceleration period and a deceleration period are required for each main scanning movement, and these periods have a significant impact on the cycle time.

[0006] Therefore, if exposure could be performed during these acceleration and deceleration periods, a significant improvement in cycle time could be expected, but no technology to make this possible has been proposed to date.

[0007] This invention has been made in view of the above problems, and aims to improve the cycle time of the exposure process by enabling exposure during the acceleration and deceleration periods in the relative movement between the exposure unit and the substrate holding unit. [Means for solving the problem]

[0008] One aspect of the present invention is an exposure method for exposing a substrate to be exposed by injecting a modulated light beam into the substrate, wherein the incidence position of the output light beam on the substrate is scanned by relatively moving an exposure unit that outputs the light beam and a substrate holding unit that holds the substrate, the relative movement speed of the exposure unit and the substrate holding unit is determined based on the signal generated by the relative movement, the light beam is injected into the substrate while changing the light intensity of the light beam in multiple stages using an optical modulator that operates at a predetermined control period, and the control period and the maximum light intensity of the light beam are changed according to the relative movement speed. Here, the control cycle is set to be inversely proportional to the relative movement speed, while the maximum light intensity is set to be proportional to the relative movement speed.

[0009] Another aspect of the present invention is an exposure apparatus comprising: an optical modulator capable of modulating light emitted from a light source in multiple steps; an exposure unit that incidents the modulated light beam onto a substrate to be exposed; a substrate holding unit that holds the substrate; a scanning movement unit that scans the incident position of the light beam on the substrate by moving the exposure unit and the substrate holding unit relative to each other; a signal output unit that outputs a signal relating to the relative movement speed between the exposure unit and the substrate holding unit; and a modulation control unit that changes the optical modulator at a predetermined control period to change the light intensity of the light beam in multiple steps, wherein the modulation control unit changes the control period and the maximum light intensity of the light beam according to the relative movement speed determined based on the signal. Here, the control cycle is set to be inversely proportional to the relative movement speed, while the maximum light intensity is set to be proportional to the relative movement speed.

[0010] In this configuration, the control period for modulating the light beam and the maximum light intensity of the light beam are changed according to the relative movement speed between the exposure unit and the substrate holding unit. This makes it possible to perform exposure appropriately even during periods when the relative movement speed is fluctuating. The basic concept is as follows.

[0011] When the relative movement speed between the exposure unit and the substrate (hereinafter simply referred to as "movement speed") changes, the amount of relative movement per unit time changes. On the other hand, if the light beam is modulated with a constant control period, that is, if the minimum unit of exposure time is kept constant regardless of speed, the distance the substrate moves during the same exposure time changes. Therefore, the minimum length of the exposure spot that can be achieved fluctuates. Specifically, the lower the movement speed, the smaller the exposure spot, and at higher speeds, it becomes larger. For example, if the movement speed is halved, the minimum length of the exposure spot is also halved.

[0012] This minimum length can be considered as the theoretical resolution in the scanning direction. Variations in resolution can lead to a decrease in drawing quality, such as causing distortion in the drawing pattern created by exposure.

[0013] For example, by changing the control period of the light beam modulation in proportion to the movement speed, it is possible to avoid such fluctuations in resolution. On the other hand, because the time that light is incident on the same location on the substrate varies, the amount of exposure at that location will differ from the intended amount. This also causes a decrease in drawing quality.

[0014] Therefore, in this invention, the relative movement speed between the exposure unit and the substrate holding unit is determined from the signal generated by the relative movement between them, and the control period and the maximum light intensity of the light beam are changed according to the result. In this way, it is possible to prevent the size of the exposure spot from fluctuating even when there is a change in the movement speed. Furthermore, by performing scaling that changes the maximum light intensity of the light beam in accordance with the change in movement speed, fluctuations in the exposure amount can also be suppressed.

[0015] In this way, the degradation of drawing quality caused by fluctuations in movement speed is suppressed, making it possible to perform exposure with the same drawing quality as the constant-speed period, even during acceleration and deceleration periods before and after the constant-speed period where the relative movement speed is constant. Therefore, exposure can be performed using at least a portion of the acceleration and deceleration periods, thereby shortening the constant-speed period. As a result, the cycle time of the exposure process can be shortened. [Effects of the Invention]

[0016] As described above, according to the present invention, the relative movement speed between the exposure unit and the substrate is determined, and the control period in light beam modulation and the maximum light intensity of the light beam are changed accordingly. This allows exposure to be performed without degrading the drawing quality even during acceleration and deceleration periods when the relative movement speed is not constant. By performing exposure even during at least a portion of the acceleration and deceleration periods in this way, the cycle time of the exposure process can be shortened. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic front view showing the general configuration of the exposure apparatus according to the present invention. [Figure 2] It is a block diagram showing an example of the electrical configuration of an exposure apparatus. [Figure 3] It is a diagram schematically showing an example of the detailed configuration of an exposure head. [Figure 4] It is a diagram showing an example of a velocity profile in the main scanning movement of a stage. [Figure 5] It is a diagram for explaining the operation of the exposure apparatus according to the present embodiment. [Figure 6] It is a diagram showing the relationship between stage speed and clock frequency. [Figure 7] It is a diagram for explaining exposure data processing for coping with changes in frequency division ratio. [Figure 8] It is a block diagram showing the concept of data processing in the exposure operation of the present embodiment. [Figure 9] It is a diagram showing an example of the relationship between input gradation and output gradation of an optical modulator. [Figure 10] It is a diagram showing an example of a reference table included in a parameter processing unit. [Figure 11] It is a flowchart showing processing executed by this exposure apparatus. MODE FOR CARRYING OUT THE INVENTION

[0018] FIG. 1 is a front view schematically showing a schematic configuration of an exposure apparatus according to the present invention, and FIG. 2 is a block diagram showing an example of the electrical configuration of the exposure apparatus of FIG. 1. In FIG. 1 and the following drawings, the X direction which is a horizontal direction, the Y direction which is a horizontal direction orthogonal to the X direction, the Z direction which is a vertical direction, and the rotation direction θ centered on a rotation axis parallel to the Z direction are appropriately shown.

[0019] The exposure apparatus 1 draws a pattern on a photosensitive material by irradiating a laser beam of a predetermined pattern onto a substrate S (exposure target substrate) on which a layer of a photosensitive material such as a resist is formed. As the substrate S, for example, various substrates such as a printed wiring board, a glass substrate for various display devices, and a semiconductor substrate can be applied.

[0020] The exposure apparatus 1 comprises a main body 11, which consists of a main body frame 111 and a cover panel (not shown) attached to the main body frame 111. Various components of the exposure apparatus 1 are arranged inside and outside the main body 11.

[0021] The interior of the main body 11 of the exposure apparatus 1 is divided into a processing area 112 and a transfer area 113. The processing area 112 mainly houses the stage 2, stage drive mechanism 3, exposure unit 4, and alignment unit 5. Outside the main body 11, an illumination unit 6 is located to supply illumination light to the alignment unit 5. In the transfer area 113, a transfer device 7, such as a transfer robot, is located to transfer substrates S to and from the processing area 112. Furthermore, a control unit 9 is located inside the main body 11, and the control unit 9 is electrically connected to each part of the exposure apparatus 1 to control the operation of each part.

[0022] The transport device 7, located in the transfer area 113 inside the main unit 11, receives unprocessed substrates S from an external transport device or substrate storage device (not shown) and loads them into the processing area 112, and unloads processed substrates S from the processing area 112 and discharges them to the outside. Loading of unprocessed substrates S and unloading of processed substrates S are performed by the transport device 7 in accordance with instructions from the control unit 9.

[0023] Stage 2 has a flat, plate-like shape and holds the substrate S placed on its upper surface in a horizontal position. Multiple suction holes (not shown) are formed on the upper surface of Stage 2, and by applying negative pressure (suction pressure) to these suction holes, the substrate S placed on Stage 2 is fixed to the upper surface of Stage 2. Stage 2 is driven by a stage drive mechanism 3.

[0024] The stage drive mechanism 3 is an XYZ-θ drive mechanism that moves the stage 2 in the Y direction (main scanning direction), X direction (sub-scanning direction), Z direction, and rotational direction θ (yaw direction). The stage drive mechanism 3 includes a Y-axis robot 31, which is a single-axis robot extending in the Y direction; a table 32 driven in the Y direction by the Y-axis robot 31; an X-axis robot 33, which is a single-axis robot extending in the X direction on the upper surface of the table 32; a table 34 driven in the X direction by the X-axis robot 33; and a θ-axis robot 35 that drives the stage 2, which is supported on the upper surface of the table 34, in the rotational direction θ relative to the table 34.

[0025] Therefore, the stage drive mechanism 3 can drive the stage 2 in the Y direction using the Y-axis servo motor of the Y-axis robot 31, drive the stage 2 in the X direction using the X-axis servo motor of the X-axis robot 33, and drive the stage 2 in the rotational direction θ using the θ-axis servo motor of the θ-axis robot 35. These servo motors are not shown in the illustration. The stage drive mechanism 3 can also drive the stage 2 in the Z direction using the Z-axis robot 37, which is not shown in Figure 1. The stage drive mechanism 3 moves the substrate S placed on the stage 2 by operating the Y-axis robot 31, X-axis robot 33, θ-axis robot 35, and Z-axis robot 37 in response to commands from the control unit 9.

[0026] The Y-axis robot 31 is equipped with a linear scale 311 that outputs a signal each time the stage 2 moves a predetermined distance (e.g., 0.1 μm) in the Y direction. Linear scales with sub-micron resolution are commercially available, and such products can be suitably used as the linear scale 311 in this embodiment. The output signal from the linear scale 311 is provided to the control unit 9. Based on this signal, the control unit 9 can determine the position and movement speed of the stage 2 in the Y direction. In other words, the output signal from the linear scale 311 is a signal that contains information regarding the position and movement speed of the stage 2 in the Y direction.

[0027] The exposure unit 4 includes an exposure head 41 positioned above the substrate S on the stage 2, and a light irradiation unit 40 which includes a light source drive unit 42, a laser emission unit 43, and an illumination optical system 44, and irradiates the exposure head 41 with laser light. Multiple exposure units 4 may be provided at different positions in the X direction.

[0028] The laser light emitted from the laser emission unit 43 by the operation of the light source drive unit 42 is irradiated onto the exposure head 41 via the illumination optical system 44. The exposure head 41 modulates the laser light emitted from the light irradiation unit using a spatial light modulator and directs it onto the substrate S moving directly below it. By exposing the substrate S with the laser light beam in this way, a pattern is drawn on the substrate S (exposure operation).

[0029] The alignment unit 5 has an alignment camera 51 positioned above the substrate S on the stage 2. This alignment camera 51 has a lens barrel, an objective lens, and a CCD image sensor, and captures alignment marks provided on the upper surface of the substrate S moving directly below it. The CCD image sensor of the alignment camera 51 is composed of, for example, an area image sensor (two-dimensional image sensor).

[0030] The illumination unit 6 is connected to the lens barrel of the alignment camera 51 via an optical fiber 61 and supplies illumination light to the alignment camera 51. The illumination light guided by the optical fiber 61 extending from the illumination unit 6 is guided through the lens barrel of the alignment camera 51 to the upper surface of the substrate S, and the reflected light from the substrate S is incident on the CCD image sensor via the objective lens. As a result, the upper surface of the substrate S is imaged and an image is acquired. The alignment camera 51 is electrically connected to the control unit 9 and acquires the image in response to instructions from the control unit 9 and transmits this image to the control unit 9.

[0031] The control unit 9 acquires the position of the alignment marks indicated by the image captured by the alignment camera 51. The control unit 9 also controls the exposure unit 4 based on the position of the alignment marks to adjust the pattern of the laser light irradiated from the exposure head 41 onto the substrate S during the exposure operation. The control unit 9 then irradiates the substrate S with modulated laser light from the exposure head 41 according to the pattern to be drawn, thereby drawing a pattern on the substrate S.

[0032] The control unit 9 performs various processes by controlling the operation of each of the above-described units. For this purpose, the control unit 9 includes a CPU (Central Processing Unit) 91, memory (RAM) 92, storage 93, input unit 94, display unit 95, and interface unit 96. The CPU 91 reads and executes a control program 931 that is pre-stored in the storage unit 93, and performs various operations described later. The memory 92 is used for calculation processing by the CPU 91, or for short-term storage of data generated as a result of calculation processing. The storage unit 93 stores various data and control programs for long-term storage. Specifically, the storage unit 93 is a non-volatile storage device such as a flash memory device or a hard disk drive device, and in addition to the control program 931 executed by the CPU 91, it stores, for example, CAD (Computer Aided Design) data 932, which is design data representing the content of the pattern to be drawn.

[0033] The input unit 94 receives user input and, for this purpose, has an appropriate input device such as a keyboard, mouse, or touch panel (not shown). The display unit 95 notifies the user by displaying and outputting various information and, for this purpose, has an appropriate display device such as a liquid crystal display panel. The interface unit 96 manages communication with external devices. For example, the interface unit 96 functions when the exposure apparatus 1 receives a control program 931 and CAD data 932 from an external source. For this purpose, the interface unit 96 may also have a function for reading data from an external recording medium.

[0034] The CPU 91 implements functional blocks such as the exposure data generation unit 911, exposure control unit 912, focus control unit 913, and stage control unit 914 in software by executing the control program 931. Note that at least a portion of each of these functional blocks may be implemented by dedicated hardware.

[0035] The exposure data generation unit 911 generates exposure data for modulating the light beam according to the pattern, based on the CAD data 932 read from the storage 93. More specifically, the exposure data generation unit 911 converts the CAD data 932, which is represented as vector data, into pixel data (raster data) in units of an appropriate grid size, and further converts the raster data into exposure data for individually controlling the light modulation elements provided on the exposure head 41.

[0036] If the substrate S is deformed, such as by distortion, the exposure data generation unit 911 modifies the exposure data according to the amount of distortion of the substrate S, thereby enabling drawing that matches the shape of the substrate S. The exposure data is sent to the exposure head 41, and the exposure head 41 modulates the laser light emitted from the light irradiation unit according to the exposure data. The modulated light beam, thus modulated according to the pattern, is irradiated onto the substrate S, and the surface of the substrate S is partially exposed to draw the pattern.

[0037] The exposure control unit 912 controls the light irradiation unit 40 to emit a laser beam having a predetermined power and spot size. The focus control unit 913 controls the projection optical system (described later) provided on the exposure head 41 to focus the laser beam onto the surface of the substrate S.

[0038] The stage control unit 914 controls the stage drive mechanism 3 to move the stage 2 for alignment adjustment and for scanning during exposure. During alignment adjustment, the position of the stage 2 is adjusted in the X, Y, Z, and θ directions so that the relative positional relationship between the substrate S placed on the stage 2 and the exposure head 41 at the start of exposure is a predetermined relationship. On the other hand, during scanning, a main scanning movement is performed by moving the stage 2 in the Y direction at a constant speed to allow the substrate S to pass below the exposure head 41, and a step feed in the X direction at a constant pitch (sub-scanning movement) is performed.

[0039] Figure 3 is a schematic diagram showing an example of the detailed configuration of an exposure head. As shown in Figure 3, the exposure head 41 is provided with a spatial light modulator 410 having a diffractive optical element 411. Specifically, the spatial light modulator 410, which is attached to the upper part of a support column 400 that extends vertically (Z direction) from the exposure head 41, is supported by the support column 400 via a movable stage 412 with the reflective surface of the diffractive optical element 411 facing downwards.

[0040] In the exposure head 41, the diffractive optical element 411 is positioned such that the normal to its reflective surface is inclined with respect to the optical axis OA of the incident light beam L. The light beam L emitted from the illumination optical system 44 enters the mirror 413 through the opening of the support column 400, is reflected by the mirror 413, and then irradiates the diffractive optical element 411. The state of each channel of the diffractive optical element 411 is switched by the control unit 9 according to the exposure data, thereby modulating the laser light beam L incident on the diffractive optical element 411.

[0041] Then, the laser light reflected from the diffractive optical element 411 as zero-order diffracted light enters the lens of the projection optical system 414, while the laser light reflected from the diffractive optical element 411 as first-order or higher diffracted light does not enter the lens of the projection optical system 414. In other words, basically, only the zero-order diffracted light reflected by the diffractive optical element 411 enters the projection optical system 414.

[0042] Light passing through the lens of the projection optical system 414 is focused by the focusing lens 415 and guided onto the substrate S as an exposure beam at a predetermined magnification. The projection optical system 414 constitutes a reduction optical system. This focusing lens 415 is attached to the focus drive mechanism 416. Then, in response to a control command from the focus control unit 913 of the control unit 9, the focus drive mechanism 416 raises and lowers the focusing lens 415 along the vertical direction (Z-axis direction), thereby adjusting the convergence position of the exposure beam emitted from the focusing lens 415 to the upper surface of the substrate S.

[0043] As shown along the optical path of the laser beam L indicated by the dashed line in Figure 3, the laser beam L guided from the light irradiation unit 40 to the exposure head 41 has a beam spot shape that extends uniformly in an elongated shape in the X direction, with the X direction as the long axis and the Z direction as the short axis. On the other hand, the modulated laser beam Lm after being modulated by the optical modulator 410 has the X direction as the long axis and the Y direction as the short axis, and its intensity in the X direction is modulated according to the exposure data. Furthermore, the exposure beam Le emitted from the projection optical system 414 toward the substrate S is a reduced version of the modulated laser beam Lm in the X and Y directions. By irradiating the surface of the substrate S with this narrowed exposure beam Le, a fine pattern can be drawn on the surface of the substrate S.

[0044] By irradiating the substrate S with an exposure beam Le modulated according to the exposure data, and moving the exposure head 41 and the substrate S relative to each other in the Y direction, a band-shaped region of the substrate S that has a width equivalent to the spot size of the exposure beam Le in the X direction and extends in the Y direction can be exposed. By repeatedly performing exposure while sequentially changing the relative position of the exposure head 41 and the substrate S in the X direction, the entire substrate S can eventually be exposed.

[0045] In this manner, by combining scanning movements in the Y direction and scanning movements in the X direction between the exposure head 41 and the substrate S, the entire substrate S can be drawn. In this specification, scanning movements in the Y direction are referred to as "main scanning movements," and the Y direction is referred to as the "main scanning direction." On the other hand, scanning movements in the X direction are referred to as "sub-scanning movements," and the Y direction is referred to as the "sub-scanning direction." In this embodiment, these scanning movements are achieved by moving the stage 2 that supports the substrate S relative to the fixed exposure head 41.

[0046] Multiple exposure units 4 having the above configuration can be provided at different positions in the X direction. In this embodiment, five sets of exposure units 4 having the same configuration are provided, and these emit exposure beams Le in parallel to perform drawing, thereby improving the throughput of the drawing process. Although these exposure units 4 can operate independently of each other, their scanning movement relative to the substrate S is uniform due to their structure.

[0047] Figure 4 shows an example of a speed profile during the main scanning movement of the stage. Consider the main scanning movement in the (+Y) direction among the scanning movements of the exposure head 41 described above. As shown in Figure 4(a), the stage 2 reciprocates between a position P1 where the (+Y) side end of the substrate S held on the upper surface is on the (-Y) side of the optical path of the output light Le of the exposure head 41, and a position P2 where the (-Y) side end of the substrate S is on the (+Y) side of the optical path of the output light Le of the exposure head 41. The symbol Dt represents the one-way travel distance of the stage 2 at this time.

[0048] For example, consider the operation of a stage 2 that is stopped at position P1, starts scanning movement in the (+Y) direction (main scanning movement) at time T0, reaches a constant speed, and then reaches position P2 and stops at time T3. In this case, as shown in Figure 4(b), the movement speed of stage 2 is zero at time T0, and then it accelerates sequentially until it reaches a preset constant speed Vc at time T1, and this constant speed is maintained until time T2. After that, stage 2 decelerates, and at time T3 its speed becomes zero and stage 2 stops.

[0049] The distance traveled in Stage 2 during this movement increases gradually during the acceleration period from time T0 to time T1, and then increases linearly with a steeper slope during the constant speed period from time T1 to time T2. During the deceleration period from time T2 onward, the increase becomes gradual again, and the distance traveled reaches its final value Dt at time T3.

[0050] The output signal of the linear scale 311 during this period is as follows. The repetition pitch of the output signal of the linear scale 311, which is output at regular intervals of movement, is represented by the symbol P. Note that, for the sake of clarity, the output signal is schematically shown here with a coarse pitch, but in reality, the output signal of the linear scale 311, which has a submicron-order position resolution, is repeatedly output at a much finer pitch.

[0051] From time T0, when Stage 2 begins to move, a signal is output from the linear scale 311. Up to time T1, the signal pitch P decreases over time as Stage 2 accelerates, and from time T1 onward, the signal is output at a constant pitch. The signal pitch Pc at this time corresponds to a constant velocity Vc. From time T2, when Stage 2 begins to decelerate, the signal pitch P also gradually decreases, and from time T3 onward, no signal is output. Thus, the output signal of the linear scale 311 is related to the moving speed of Stage 2, and the moving speed of Stage 2 can be calculated from the position resolution of the linear scale 311 and the signal pitch P.

[0052] Figure 5 is a diagram illustrating the operation of the exposure apparatus of this embodiment. Of these, Figure 5(a) shows the exposure operation of the conventional technology as a comparative example, and Figure 5(b) shows the exposure operation of this embodiment. In these figures, "exposure distance" is a measure representing the length of the area on the substrate S that is exposed in one main scan movement. Here, the exposure distance is expressed as the ratio of the length of the exposed area to the total length of the area to be exposed in one main scan movement. Therefore, when the exposure of the entire area to be exposed in one main scan movement is completed, the exposure distance becomes 100%.

[0053] In conventional technology, as shown in Figure 5(a), exposure is performed during a constant-speed period from time T1 to time T2, when the stage movement speed is constant at a constant speed Vc. During this time, the exposure distance increases linearly. With this method, stable drawing quality can be obtained because the stage movement speed is constant during the exposure period. On the other hand, exposure is not performed during the acceleration period from time T0 to time T1, and during the deceleration period from time T2 to time T3, which hinders efforts to shorten the cycle time.

[0054] When exposing an entire substrate S by repeating the main scanning movement multiple times, such invalid periods occur with each main scanning movement, and these can accumulate, resulting in a very large time loss. To shorten these invalid periods, it is conceivable to increase the acceleration during the acceleration and deceleration periods, but rapid acceleration and deceleration are not necessarily desirable from the standpoint of stable stage movement.

[0055] In this embodiment, by employing the method described later, it is possible to perform exposure without degrading the drawing quality even when the stage movement speed fluctuates. Therefore, by performing exposure even during at least a portion of the acceleration and deceleration periods, the time required for one main scan movement can be shortened, and as a result, the cycle time can be improved.

[0056] In other words, as shown in Figure 5(b), in this embodiment, exposure begins at time Ts, which is after time T0 when the movement of stage 2 begins, and when the movement speed reaches a threshold Vth that is lower than a constant speed Vc. Naturally, the exposure start time Ts is earlier than the time T1 at which exposure becomes possible in the conventional technology. Exposure continues until time Te, when the stage movement speed decreases and reaches the threshold Vth.

[0057] Thus, because exposure occurs during both acceleration and deceleration periods, the length of the area to be exposed within the constant-speed period (exposure distance) is shorter than in conventional techniques. Therefore, the constant-speed period can be shortened compared to conventional techniques, thereby reducing the cycle time. The smaller the speed threshold Vth, the greater the effect of reducing the cycle time.

[0058] In this embodiment, the speed threshold at the start of exposure and the speed threshold at the end of exposure are equal, but they may be different. Also, in this example, exposure is performed during both the acceleration and deceleration periods, but exposure may be performed during only one of the acceleration or deceleration periods.

[0059] Next, we will describe the exposure method of this embodiment, which enables exposure without degrading drawing quality even during periods when the stage movement speed fluctuates, as described above. In the prior art, the effects that appear when the relative movement speed of the substrate S with respect to the exposure head 41 fluctuates are mainly the following two points. (1) Because the distance the substrate S moves per unit time changes, the exposed area changes even if the light beam irradiation time is the same. In other words, the size of the exposure spot in the main scanning direction fluctuates. (2) When considering a single point on the substrate S, the time it takes for light to be incident changes depending on the speed of movement. In other words, the amount of exposure at that position fluctuates.

[0060] Regarding the "fluctuation in relative movement speed" here, since the purpose is to perform exposure during acceleration and deceleration periods, we only need to consider cases where the speed falls below a predetermined constant speed Vc. In this case, for (1) above, the effect of Stage 2 moving at a speed lower than the specified speed will result in the size of the exposure spot becoming smaller than it should be. For (2), the effect of increasing the amount of exposure to each point will result in it being larger than it should be.

[0061] Based on these considerations, a possible solution to (1) above is to ensure that the irradiation time per spot increases as the stage movement speed decreases. For example, in a modulation method using a diffractive optical element that switches the intensity of diffracted light at a predetermined control period, the control period should be changed according to the stage movement speed. Specifically, the control period should be increased as the stage movement speed decreases. For example, it is conceivable to set the control period inversely proportional to the stage movement speed. This is because it is expected that the variations in spot size caused by each will cancel each other out by maintaining the product of the stage movement speed and the control period at a constant value.

[0062] The frequency of the signal repeatedly output from the linear scale 311 as stage 2 moves is proportional to the stage movement speed. In other words, the period of the signal is inversely proportional to the stage movement speed. From this, it is conceivable to use the output signal of the linear scale 311 as a reference clock, divide it by an appropriate frequency division ratio, and use the resulting clock as a control clock to control the optical modulator 410. Alternatively, a reference clock generated from a separately prepared master clock can be used to generate a control clock with a frequency corresponding to the stage movement speed determined from the output signal of the linear scale 311.

[0063] On the other hand, as a countermeasure to (2) above, it is conceivable to reduce the intensity of the light beam as the stage movement speed decreases. For example, changing the intensity of the light beam before modulation, such as by controlling the output from the light source, is not always easy from the standpoint of the operational stability and response speed of the light source. If the optical modulator 410 is capable of multi-level modulation rather than simple ON / OFF binary modulation, the objective can be achieved by scaling the light intensity level of the output light according to the stage movement speed. For example, if the stage movement speed is half of the specified speed, the maximum light intensity of the output light can be set to half of the maximum light intensity at the specified speed, and the light intensity levels below that can also be scaled appropriately to avoid excessive exposure at low speeds.

[0064] In this way, by manipulating the control cycle and output gradation level of the optical modulator 410 according to the actual stage movement speed, exposure with a constant drawing quality becomes possible not only during the constant speed period but also during the acceleration and deceleration periods. As a result, even if the speed profile and constant speed Vc during acceleration and deceleration are the same, the constant speed period can be shortened and the cycle time can be improved.

[0065] This reduction in constant-speed period can be achieved by shortening the travel distance Dt of Stage 2, that is, by setting the start position P1 and end position P2 of Stage 2 in Figure 4(a) inward compared to the conventional technology. As a result, the stroke of Stage 2's reciprocating movement during the main scanning movement (travel distance Dt shown in Figure 4(a)) can be shortened. This not only has the effect of shortening the cycle time, but can also serve as a basis for miniaturizing the stage drive mechanism 3 when designing a new device.

[0066] As described above, one feature of the exposure operation in this embodiment is that the control period of the optical modulator 410 is changed according to the stage movement speed. In principle, a clock that defines the control period is generated to have a frequency proportional to the stage movement speed, and this is supplied to the control circuit of the optical modulator 410.

[0067] However, in reality, optical modulators, particularly optical modulators 410 using diffractive optical elements 411, sometimes have a preferred range for the control period due to structural or product specification constraints. In other words, the frequency of the control clock cannot be determined completely freely; there is an appropriate range. For example, when using Silicon Light Machines' GLV (Grating Light Valve; "GLV" is a registered trademark of the company) element as the diffractive optical element 411, its appropriate operating frequency is considered to be between 50 kHz and 250 kHz. Therefore, the clock frequency must be set within this appropriate range.

[0068] Figure 6 shows the relationship between stage speed and clock frequency. As described above, in this embodiment, the control period for operating the optical modulator 410 is changed according to the stage movement speed. More specifically, the frequency fc of the control clock that operates the optical modulator 410 is set to be proportional to the measured value of the stage movement speed estimated from the output of the linear scale 311. Qualitatively, the horizontal axis in Figure 6 is equivalent whether it represents the stage movement speed or the linear scale output.

[0069] Figure 6 shows an example of the settings. As shown by the solid line, the control clock frequency fc is determined so that the clock frequency fc corresponding to the maximum speed in the main scanning movement of Stage 2, for example, the constant speed Vc during the constant speed period, is close to the maximum value fcmax within the appropriate range. If the stage movement speed is lower, the clock frequency also changes proportionally.

[0070] In regions with low stage movement speeds, the control clock frequency fc may fall below the lower limit fcmin. Since the optical modulator 410 cannot operate correctly with such a control clock frequency, the clock frequency fc must be changed. For example, this can be done by changing the frequency division ratio used to generate the control clock from the reference clock.

[0071] For example, as shown in Figure 6, when the clock frequency fc approaches the lower limit fcmin, the division ratio is halved, doubling the clock frequency. This prevents the clock frequency fc from falling below the lower limit fcmin. Furthermore, when the stage movement speed decreases and the clock frequency fc approaches the lower limit fcmin, the division ratio is halved again, doubling the clock frequency. By repeating this process sequentially, it becomes possible to generate a control clock with a frequency within the appropriate range even at extremely low speeds.

[0072] Furthermore, when the stage movement speed is close to zero, the accuracy of speed calculation based on the output signal from the linear scale 311 decreases significantly. For this reason, it is preferable to avoid exposure in the extremely low speed range. The threshold Vth shown in Figure 5(a) can be used to prohibit exposure in such extremely low speed ranges and stabilize the drawing quality.

[0073] As mentioned above, the control period of the optical modulator 410 is related to the resolution in the main scanning direction, and changing the frequency division ratio when generating the control clock frequency fc significantly changes the resolution in the main scanning direction. Therefore, measures must be taken to ensure that there is no difference in drawing quality before and after the change.

[0074] Figure 7 illustrates the exposure data processing required to accommodate changes in the frequency division ratio. As shown in Figure 7(a), the raster data representing the pattern to be drawn is obtained by unfolding the pattern, which was represented in CAD data, into a bitmap with a unit grid of a predetermined size. For the unit grid size, for example, 1 μm can be used as a standard value. The grid size in the Y direction is defined by the frequency fc of the control clock.

[0075] Here, for example, if the frequency fc of the control clock doubles due to a change in the frequency division ratio during clock generation, the resolution in the Y direction also doubles. Therefore, the grid size is halved to 0.5 μm. Since the original raster data is created only in 1 μm units, if exposure data is created from this raster data as is, data will be missing for each grid, as shown in Figure 7(b).

[0076] Therefore, when creating exposure data from raster data, missing data is interpolated, for example, by holding the previous value. In this way, as shown in Figure 7(c), it is possible to generate exposure data that is free of missing data and identical to the original data shown in Figure 7(a). The same applies when the clock frequency fc is quadrupled and the grid size is (1 / 4), as shown in Figure 7(d).

[0077] By controlling the optical modulator 410 based on the interpolated exposure data and the multiplied control clock, the optical beam can be modulated, allowing the pattern represented by the original CAD data and raster data to be exposed without compromising drawing quality.

[0078] As described above, by basically making the control period of the optical modulator 410 follow the stage movement speed, or more specifically, change it inversely proportionally, it is possible to perform exposure with the same drawing quality as the constant-speed period even during the acceleration and deceleration periods when the stage movement speed fluctuates. Furthermore, the effect of changes in exposure amount due to speed changes can be suppressed by scaling the light intensity level of the output light beam according to the stage movement speed.

[0079] However, if the control clock frequency determined from the stage movement speed does not fall within the appropriate range, the clock is multiplied (or divided) as needed to generate a control clock within the appropriate range, and the grid size (resolution) of the main scanning direction when generating exposure data from the CAD data or raster data that forms the basis of the drawing is changed accordingly. By doing so, it becomes possible to perform exposure while maintaining the desired drawing quality over a wide speed range.

[0080] Based on the above considerations, the exposure operation of this embodiment is configured as follows.

[0081] Figure 8 is a block diagram illustrating the concept of data processing in the exposure operation of this embodiment, and corresponds to a rewritten version of the exposure data generation unit 911 and exposure control unit 912 in Figure 2 as a more practical combination of processing blocks.

[0082] As the main scanning movement of Stage 2 occurs, the signal output from the linear scale 311 is input to the speed calculation unit 912a of the exposure control unit 912. The speed calculation unit 912a calculates the stage movement speed from the period of the given signal. The determined stage movement speed is provided to the parameter determination unit 912b. From the given stage movement speed, the parameter determination unit 912b determines the division ratio or multiplication factor for determining the control clock frequency fc, the grid size when creating exposure data, and the light intensity coefficient for scaling the light intensity level of the output light beam. For this purpose, the parameter determination unit 912b has a reference table 912c, which will be described later.

[0083] The clock generation unit 912d generates a control clock by dividing or multiplying the reference clock and supplies it to the exposure head 41. The reference clock can be the output signal from the linear scale 311, a master clock (MCLK) separately generated for the operation of each part, or a clock obtained by dividing these at an appropriate division ratio. When generating the control clock, information regarding the division ratio or multiplication ratio determined by the parameter determination unit 912b is used. This allows for the generation of a control clock corresponding to the grid size when creating exposure data.

[0084] Meanwhile, in the exposure data generation unit 91, the RIP (Raster Image Processor) unit 911a expands the CAD data, which is provided in advance as design data, into pixel units with a predetermined grid size to create raster data. However, the raster data here does not take into account the effect of the stage movement speed, and the grid size is uniquely determined according to the resolution required for drawing.

[0085] The data processing unit 911b creates exposure data from raster data, and in doing so, modifies the grid size and interpolates the data as necessary based on the grid size information provided by the parameter determination unit 912b. It also scales the light intensity level of the output light based on the light intensity coefficient information provided by the parameter determination unit 912b. Specifically, scaling is achieved by multiplying the gradation value in the exposure data created by the conventional technology, which assumes no velocity fluctuations, by the light intensity coefficient Ci determined by the parameter determination unit 912b.

[0086] For example, if the tonal values ​​in exposure data are represented by two values, 100% (on) and 0% (off), relative to the maximum achievable tonal range, and the light intensity coefficient Ci is 0.9, scaling can be achieved by setting the tonal value when on to 90%. Similarly, even when intermediate tones are set between these values, the scaled tonal value can be determined by multiplying the tonal value at that time by the light intensity coefficient Ci.

[0087] Figure 9 shows an example of the relationship between the input and output tonal levels of an optical modulator. For example, in optical modulators using diffractive optical elements such as GLV, the response sensitivity to the input tonal level is generally nonlinear, as shown in Figure 9. By reassigning the tonal levels from 0% to 100% using only the region that can be considered nearly linear (tonal values ​​G0 to G1), it becomes possible to accurately perform multi-tone modulation by making the tonal level of the output light linear with respect to the input tonal value. In this case, scaling by the light intensity coefficient Ci (0 ≤ Ci ≤ 1) is performed using the relationship shown in Figure 9, where the scaled tonal value Gy is obtained, for example, by the following equation for any tonal value Gx before scaling: Gy = (Gx - G0) × Ci + G0 This method makes it feasible. Furthermore, it is also possible to represent gradations using regions outside of those that can be considered linear.

[0088] In addition to these adjustments, the data processing unit 911b performs various processing, such as distortion correction, to create exposure data, which is then provided to the exposure head 41. Since this data processing method is publicly known, a detailed explanation is omitted.

[0089] In the exposure head 41, the optical modulator 410 is driven based on a control clock and exposure data optimized according to the stage movement speed, as described above, and drawing is performed on the substrate S. Therefore, exposure is possible not only during the constant-speed period when the stage 2 moves at a constant speed Vc, but also before and after that period, i.e., during the acceleration and deceleration periods. Even in this case, there is no deterioration in drawing quality due to speed changes.

[0090] Figure 10 shows an example of a reference table held by the parameter processing unit. The reference table 912c holds information for generating the stage movement speed calculated by the speed calculation unit 912a, the corresponding control clock (frequency division ratio or multiplication factor), information regarding the grid size during data processing, and information regarding the light intensity coefficient. The parameter determination unit 912b can immediately determine these parameters by referring to the reference table 912c based on the stage movement speed information provided by the speed calculation unit 912a.

[0091] Let's explain an example of specific numerical values. Basically, the higher the stage movement speed, the larger the clock division ratio (or smaller in the case of frequency multiplication), and the higher the stage movement speed, the higher the clock frequency generated at the same division ratio or frequency multiplication ratio (generally proportional to the speed). Also, the grid size is set to increase in steps as the stage movement speed increases. Furthermore, the light intensity coefficient Ci is set to be roughly proportional to the stage movement speed. Here, the light intensity coefficient Ci is shown as a relative value with the value at a stage movement speed of 240 mm / sec set to 100%.

[0092] Figure 11 is a flowchart showing the process performed by the exposure apparatus configured as described above. This operation is achieved when the CPU 91 of the control unit 9 executes a control program 931 pre-recorded in the storage 93, causing each part of the apparatus to perform a predetermined operation.

[0093] First, the substrate S to be exposed is set on stage 2 (step S101), and the maximum scanning speed for the exposure operation is set (step S102). The maximum scanning speed here can be calculated and set from the required exposure amount and the light intensity of the light source, within the range of the main scanning movement speed that the device can achieve. Alternatively, it may be configured so that the user can set it arbitrarily. For example, exposure may be performed with a reduced main scanning movement speed in order to achieve higher resolution drawing than usual. For this purpose, a function is provided that allows the user to set the maximum scanning speed according to their wishes.

[0094] Furthermore, after the substrate S is set, alignment adjustment is performed to match the orientation of the substrate S on the stage 2 with the position of the drawing pattern (step S103). Since there are many known techniques for alignment adjustment, a detailed explanation is omitted here.

[0095] After alignment adjustment, stage 2 starts the main scan movement from a predetermined starting position (position P1 shown in Figure 4(a)) based on a pre-prepared speed profile corresponding to the set maximum scanning speed (step S104). When the substrate S advances to a position where the stage movement speed exceeds the speed threshold Vth and exposure can be started (exposure start position Ts shown in Figure 5(b)) (step S105), exposure is started.

[0096] Specifically, the stage movement speed at that time is determined from the output of the linear scale 311 (step S106), and from this result, the frequency division ratio or multiplication factor for control clock generation, grid size, and light intensity coefficient are determined (step S107). Based on these, a control clock is generated, and exposure data is created from the raster data (step S108).

[0097] These are sent to the exposure head 41, and a light beam modulated based on the exposure data is irradiated onto the substrate S to perform exposure (step S109). The process from steps S106 to S109 is repeatedly executed until the substrate S reaches the exposure end position in one main scan movement (NO in step S110). This ensures that exposure is performed in accordance with the stage movement speed at that time.

[0098] When the substrate S reaches the exposure end position (indicated as Te in Figure 5(b)) (YES in step S110), the main scanning movement is terminated (step S111), and the stage 2 stops at the movement stop position P2 (Figure 4(a)). If the entire exposure of the substrate S is complete (YES in step S112), the processed substrate S is discharged and the process is terminated (step S114).

[0099] Otherwise (NO in step S112), a sub-scan movement is performed to move stage 2 by a predetermined pitch in the sub-scan direction (X direction) (step S113), and the process returns to step S104 to restart the main scan movement.

[0100] In this way, the entire substrate S is exposed. During this time, the control clock and exposure data for controlling the optical modulator 410 are adjusted in real time according to the stage movement speed detected as it occurs. Therefore, exposure can be performed with the same drawing quality as the constant speed period, not only during the constant speed period when the stage movement speed is constant at the set maximum scanning speed, but also during the acceleration and deceleration periods before and after it. Consequently, the constant speed period can be shortened, and the start and end positions of the movement in the main scanning movement can be set further inward than in the conventional technology. As a result, exposure can be performed with a shorter cycle time than in the conventional technology, and the stroke in the reciprocating movement can be shortened.

[0101] According to the inventor's experiments, even when the speed profile during acceleration and deceleration periods was kept the same, shortening the constant speed period resulted in an overall reduction in cycle time of approximately 20%.

[0102] Furthermore, by reducing the stroke during reciprocating movement in this way, the cycle time is shortened, eliminating the need for additional materials or energy consumption, and thus allowing for energy savings through reduced cycle time. In addition, the reduced movement stroke allows for the miniaturization of the device, which also contributes to resource and energy conservation and reduces the environmental impact.

[0103] As described above, in the exposure apparatus 1 of this embodiment, the stage 2 and the stage drive mechanism 3 function as the "substrate holding unit" and the "scanning and moving unit" of the present invention, respectively. Furthermore, the control unit 9, in particular the exposure control unit 912, functions as the "modulation control unit" of the present invention, and the reference table 912c corresponds to the "table" of the present invention. Furthermore, the exposure data generation unit 911 functions as the "exposure data generation unit" of the present invention. Furthermore, the light irradiation unit 40 functions as the "light source" of the present invention, while the exposure head 41 functions as the "exposure unit" of the present invention. In addition, in the above embodiment, the linear scale 311 functions as the "signal output unit" of the present invention, and the optical modulator 410 functions as the "optical modulator" of the present invention.

[0104] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, in the above embodiments, a diffractive optical element, such as a GLV element, is used as the modulation element of the optical modulator 410, but the optical modulation element suitable for the present invention is not limited to this, and various types that can modulate a light beam of a constant intensity in multiple levels can be applied. For example, the PLV (Planar Light Valve) element, a two-dimensional diffractive optical element that has been put into practical use by Silicon Light Machines, is also a suitable optical modulation element for the present invention.

[0105] Furthermore, in the above embodiment, for example, a linear scale 311 is provided as a means for outputting a signal generated in conjunction with stage movement in order to calculate the stage movement speed. However, such signal output means are not limited to this. For example, a method of detecting the position and speed of the stage by counting the number of pulses supplied to the stepping motor for stage drive can be applied. Alternatively, the stage movement speed can be determined using appropriate detection means such as a position sensor or a rotary encoder.

[0106] Furthermore, in the above embodiment, each parameter is determined by referring to the reference table 912c based on the stage movement speed obtained from the output of the linear scale 311. However, any method for determining the parameters in the same manner may be used without using a reference table. For example, the parameters may be calculated by substituting the obtained stage movement speed into an appropriate calculation formula.

[0107] Furthermore, in the above embodiment, scanning movement is achieved by the movement of the stage 2 supporting the substrate S relative to the fixed exposure head 41. Alternatively, for example, the substrate may be supported in a stationary state while the exposure head moves.

[0108] For example, in the main scanning movement of the above embodiment, a constant-speed period is provided during which the scanning movement speed remains constant, and exposure is performed including the acceleration and deceleration periods before and after this period. Alternatively, exposure may be omitted during either the acceleration or deceleration period. Furthermore, since the effects of speed fluctuations can be suppressed by applying the present invention, it is also possible to perform exposure without providing a constant-speed period. In addition, multiple constant-speed periods may be provided in a single main scanning movement, with acceleration or deceleration periods in between.

[0109] Furthermore, the functions of the exposure control unit 912 in this embodiment can be realized either by using dedicated hardware or by using software. From the viewpoint of processing speed, using dedicated hardware is more practical, but the method of realizing it by software can also be implemented by updating the software of an existing exposure apparatus to one that incorporates a program for realizing the method of the present invention.

[0110] As described above with examples of specific embodiments, in the exposure method according to the present invention, the maximum light intensity can be set in proportion to the relative movement speed. When the irradiation time and light intensity are the same, the exposure amount at one location on the substrate increases inversely proportional to the relative movement speed as the relative movement speed slows down. Therefore, scaling the maximum light intensity in proportion to the relative movement speed makes it possible to cancel out this effect.

[0111] Furthermore, relative movement may include accelerated movement in which the relative movement speed increases, constant-velocity movement at a constant relative movement speed, and deceleration movement in which the relative movement speed decreases. In this case, the incidence of the light beam on the substrate may include at least a portion of the period of accelerated movement and the period of deceleration movement. According to the present invention, since the influence of fluctuations in relative movement speed on drawing quality is reduced, it is possible to shorten the period of constant-velocity movement and improve the cycle time by performing exposure during the period of accelerated or deceleration movement in this way.

[0112] Furthermore, for example, the relative movement speed during constant-speed movement may be adjustable. With such a configuration, depending on the required resolution, there may be cases where rendering quality is prioritized and cases where throughput is prioritized. By making the speed during constant-speed movement adjustable, it becomes possible to meet such requirements.

[0113] Furthermore, for example, the control period may be configured to be changed within a predetermined variable range. In devices capable of optical modulation, an optimal operating frequency may be specified due to constraints such as response speed. By defining a variable range for the control period, it is possible to operate even devices with such constraints appropriately.

[0114] Furthermore, in an exposure method and exposure apparatus configured to modulate a light beam based on exposure data in which the pattern to be formed by exposure is represented in pixel units having a predetermined grid size, the grid size may be configured to be changed in steps according to the relative movement speed. Since fluctuations in the relative movement speed change the resolution in the scanning movement direction, optimizing the grid size accordingly makes it possible to maintain good drawing quality.

[0115] In this case, the control clock that defines the control period may be generated by dividing a predetermined reference clock, and the division ratio may be set according to the relative movement speed. In this case, a signal whose period changes according to the relative movement speed, in particular a signal that changes periodically at a speed proportional to the relative movement speed, can be suitably used as the reference clock.

[0116] Furthermore, the exposure apparatus according to the present invention may include a table that associates the relative movement speed with the corresponding control period and maximum light intensity. In this case, the modulation control unit can determine the control period and maximum light intensity by referring to the table based on the determined relative movement speed. With such a configuration, it is possible to immediately determine the control period and maximum light intensity once the relative movement speed is determined, and even in situations where the relative movement speed is constantly changing, it is possible to perform exposure under optimal conditions in response.

[0117] Furthermore, in the present invention, for example, a configuration can be adopted in which a main scanning movement, which moves the exposure unit and the substrate holding unit in the main scanning direction, and a sub-scanning movement, which moves the exposure unit and the substrate holding unit in a sub-scanning direction intersecting the main scanning direction, are repeatedly performed, and a light beam is incident on the substrate during the main scanning movement. By combining the main scanning movement and the sub-scanning movement in this way, a wide area of ​​the substrate can be exposed efficiently. In this case, since a period for acceleration and deceleration occurs with each main scanning movement, the effect of shortening the cycle time in the main scanning movement is particularly significant when processing the entire substrate. [Industrial applicability]

[0118] This invention is particularly suitable for the technical field of exposing substrates to form patterns on substrates such as semiconductor substrates, semiconductor package substrates, printed wiring substrates, or glass substrates. [Explanation of Symbols]

[0119] 1. Exposure apparatus 2 stages (substrate holding section) 3. Stage drive mechanism (scanning movement section) 9. Control Unit (Modulation Control Unit) 40 Light irradiation part (light source) 41. Exposure head (exposure unit) 311 Linear scale (signal output section) 410 Optical modulator 911 Exposure Data Generation Unit 912 Exposure Control Unit (Modulation Control Unit) 912c Reference Table (Table) L laser light beam Le exposure beam (light beam) S substrate

Claims

1. In an exposure method in which a modulated light beam is incident on a substrate to be exposed, The exposure unit that outputs the light beam and the substrate holding unit that holds the substrate are moved relative to each other to scan the incident position of the output light beam on the substrate. Based on the signal generated by the aforementioned relative movement, the relative movement speed between the exposure unit and the substrate holding unit is determined. The light beam is incident on the substrate while the light intensity of the light beam is changed in multiple stages by a light modulator that operates at a predetermined control period. The control period and the maximum light intensity of the light beam are changed according to the relative movement speed, and at this time, An exposure method wherein the control period is set to be inversely proportional to the relative movement speed, while the maximum light intensity is set to be proportional to the relative movement speed.

2. The relative movement includes accelerated movement in which the relative movement speed increases, constant-speed movement at a constant relative movement speed, and decelerated movement in which the relative movement speed decreases. The exposure method according to claim 1, wherein the incidence of the light beam onto the substrate includes at least a portion of the period of acceleration and the period of deceleration.

3. The exposure method according to claim 2, wherein the relative movement speed in the constant-speed movement can be changed and set.

4. The exposure method according to claim 1, wherein the control period is changed within a predetermined variable range.

5. The exposure method according to claim 4, wherein a control clock defining the control period is generated by dividing a predetermined reference clock, and the division ratio is set according to the relative moving speed.

6. The exposure method according to claim 5, wherein the light beam is modulated based on exposure data in which the pattern to be formed by exposure is represented in pixel units having a predetermined grid size, and the grid size is changed in steps according to the relative movement speed.

7. The exposure method according to claim 5, wherein the reference clock is a signal whose period changes according to the relative movement speed.

8. The exposure method according to claim 5, wherein the signal changes periodically at a speed proportional to the relative moving speed.

9. An exposure unit having a light modulator capable of modulating light emitted from a light source in multiple shades, and which incidents the modulated light beam onto a substrate to be exposed, A substrate holding portion for holding the substrate, A scanning movement unit that moves the exposure unit and the substrate holding unit relative to each other to scan the incident position of the light beam on the substrate, A signal output unit that outputs a signal relating to the relative movement speed between the exposure unit and the substrate holding unit, A modulation control unit that changes the light intensity of the light beam in multiple stages by changing the light modulator at a predetermined control cycle, and Equipped with, The modulation control unit changes the control period and the maximum light intensity of the light beam according to the relative moving speed determined based on the signal, and at this time, An exposure apparatus in which the control cycle is set to be inversely proportional to the relative movement speed, while the maximum light intensity is set to be proportional to the relative movement speed.

10. The signal output unit outputs the signal which changes periodically at a speed proportional to the relative movement speed. The exposure apparatus according to claim 9, wherein the modulation control unit generates a control clock that defines the control period at a period proportional to the period of the signal and provides it to the exposure unit.

11. The exposure apparatus according to claim 10, wherein the modulation control unit divides the signal by a predetermined reference clock at a frequency division ratio set according to the relative movement speed to generate the control clock.

12. The exposure apparatus according to claim 11, further comprising an exposure data generation unit that generates exposure data representing a pattern to be formed by exposure in pixel units having a predetermined grid size, and provides this data to the exposure unit, and changes the grid size in steps according to the relative movement speed.

13. The exposure apparatus according to claim 9, comprising a table relating the relative moving speed to the corresponding control period and the maximum light intensity, wherein the modulation control unit determines the control period and the maximum light intensity by referring to the table.

14. The scanning movement unit repeatedly performs a main scanning movement that moves the exposure unit and the substrate holding unit in the main scanning direction, and a sub-scanning movement that moves the exposure unit and the substrate holding unit in a sub-scanning direction intersecting the main scanning direction. The exposure apparatus according to claim 9, wherein the exposure unit incidents the light beam onto the substrate during the main scanning movement.

Images