JP7765323B2 - Exposure apparatus and exposure method - Google Patents

Description

This invention relates to a technique for exposing a substrate to light in order to draw a pattern on a substrate such as a semiconductor substrate, a printed wiring board, or a glass substrate.

One technique for forming patterns such as wiring patterns on various substrates, including semiconductor substrates, printed wiring boards, and glass substrates, involves irradiating a photosensitive layer formed on the surface of the substrate with a light beam modulated according to exposure data, thereby exposing the photosensitive layer. For example, Patent Document 1 discloses an imaging device that uses an optical modulator to modulate a laser light beam (line beam) with a flat beam spot and then irradiates the substrate to perform imaging on the substrate. In this technology, laser light emitted from multiple laser light sources (laser diodes) is combined to generate a single line beam, generating a high-intensity line beam with a uniform intensity distribution.

JP 2015-192080 A

Patent Document 1 describes the configuration of an illumination optical system for obtaining a line beam with a uniform intensity distribution from multiple light sources. However, no consideration is given to dealing with fluctuations in the laser light over time that may occur in each light source. For example, heat generation or mechanical vibrations in components may cause a deviation in the direction of laser light emission from one of the light sources. In such cases, the spot diameter of the exposure beam on the substrate surface increases, leading to a decrease in drawing resolution. Furthermore, if the light intensity of one of the light sources decreases or the light source no longer lights up, insufficient exposure may occur.

In this way, fluctuations over time in the laser light emitted by the light source can cause defects in the pattern formed by drawing, and can reduce substrate productivity. For this reason, it can be said that the above-mentioned conventional technology still has room for improvement in terms of dealing with fluctuations over time in the light source that can occur during drawing.

This invention was developed in consideration of the above-mentioned problems, and aims to provide a technology for exposing and drawing on a substrate with laser light beams generated using multiple light sources, which can appropriately deal with fluctuations in the light sources over time that may occur during drawing.

One aspect of the exposure device according to the present invention comprises an exposure unit having multiple laser light sources, synthesizing laser light emitted from the multiple laser light sources to generate a single laser light beam, modulating the laser light beam based on exposure data, and irradiating the substrate to be exposed as an exposure beam to perform drawing; a detection unit that detects the laser light beam on its optical path; and a control unit that controls the exposure conditions for the substrate. Here, the control unit executes a predetermined error process when the spot size of the laser light beam detected by the detection unit during drawing is outside a predetermined optimum range.

Another aspect of the exposure method according to the present invention is an exposure method in which laser light emitted from multiple laser light sources is combined to generate a single laser light beam, which is modulated based on exposure data and irradiated as an exposure beam onto a substrate to be exposed, thereby drawing. The laser light beam is detected along its optical path, and if the spot size of the laser light beam detected during the drawing operation falls outside a predetermined appropriate range, a predetermined error process is executed.

In an invention configured in this manner, the spot size of the laser light beam is detected along the optical path of the laser light beam, which is formed by combining laser light emitted from each of multiple laser light sources. If the optical axis of any of the laser light sources shifts or the light intensity increases, the spot size increases, while if the light intensity of any of the laser light sources decreases or is turned off, the spot size decreases. Therefore, by executing error processing when it is detected that the spot size is outside the appropriate range, it is possible to take appropriate measures in response to fluctuations in the light source over time that may occur during drawing.

As described above, according to the present invention, by detecting fluctuations in the spot size along the optical path of the laser light beam, it is possible to take appropriate action even if one of multiple laser light sources stops operating correctly, thereby suppressing the decline in productivity that could occur if drawing operations were to continue as is.

1 is a front view showing a schematic configuration of an exposure apparatus according to the present invention; FIG. 2 is a block diagram showing an example of the electrical configuration of the exposure apparatus of FIG. 1 . FIG. 2 is a diagram showing the configuration of a light irradiation unit. FIG. 2 is a diagram schematically illustrating an example of a detailed configuration of an exposure head. 5 is a flowchart showing processing executed by the exposure apparatus of the present embodiment. FIG. 10 is a schematic diagram illustrating a job when a plurality of exposure heads are provided. 10 is a flowchart showing a first mode of error processing. 10 is a flowchart showing a second mode of error processing. FIG. 10 is a diagram illustrating an example of a GUI screen after an abnormality occurs.

Figure 1 is a front view showing a schematic overview of the configuration of an exposure apparatus according to the present invention, and Figure 2 is a block diagram showing an example of the electrical configuration of the exposure apparatus of Figure 1. In Figure 1 and the following figures, the horizontal X direction, the horizontal Y direction perpendicular to the X direction, the vertical Z direction, and the rotation direction θ about a rotation axis parallel to the Z direction are shown as appropriate.

The exposure device 1 draws a pattern on a substrate S (substrate to be exposed) on which a layer of photosensitive material such as resist has been formed, by irradiating the substrate S with a predetermined pattern of laser light. The substrate S can be a variety of substrates, including printed wiring boards, glass substrates for various display devices, and semiconductor substrates.

The exposure apparatus 1 has a main body 11, which is composed 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 both inside and outside the main body 11.

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 contains the stage 2, stage drive mechanism 3, exposure unit 4, and alignment unit 5. Furthermore, an illumination unit 6 that supplies illumination light to the alignment unit 5 is located outside the main body 11. The transfer area 113 contains a transport device 7, such as a transport robot, that transports substrates S into and out of the processing area 112. Furthermore, a control unit 9 is located inside the main body 11, and is electrically connected to each part of the exposure apparatus 1 to control the operation of each of these parts.

The transport device 7, located in the transfer area 113 inside the main body 11, receives unprocessed substrates S from an external transport device or substrate storage device (not shown) and transports (loads) them into the processing area 112, and also unloads processed substrates S from the processing area 112 and sends them out. The loading of unprocessed substrates S and unloading of processed substrates S are performed by the transport device 7 in response to instructions from the control unit 9.

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

The stage drive mechanism 3 is an X-Y-Z-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 top 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, supported on the top surface of the table 34, in the rotational direction θ relative to the table 34.

Therefore, the stage driving 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. The stage driving mechanism 3 can also drive the stage 2 in the Z direction using the Z-axis robot 37, which is not shown in FIG. 1. The stage driving 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.

The exposure unit 4 has an exposure head 41 positioned above the substrate S on the stage 2, and a light irradiation unit 40 that 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.

When the light source driver 42 is activated, laser light emitted from the laser emitter 43 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 irradiator using a spatial light modulator, and directs it onto the substrate S moving directly below it. In this way, the substrate S is exposed to the laser light beam, and a pattern is written on the substrate S (exposure operation).

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 an image of an alignment mark provided on the top surface of the substrate S moving directly below it. The CCD image sensor provided in the alignment camera 51 is, for example, an area image sensor (two-dimensional image sensor).

The lighting 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 lighting unit 6 is directed to the top surface of the substrate S via the lens barrel of the alignment camera 51, and the light reflected from the substrate S is incident on the CCD image sensor via the objective lens. This results in an image of the top surface of the substrate S being captured. The alignment camera 51 is electrically connected to the control unit 9 and captures and transmits captured images in accordance with instructions from the control unit 9.

The control unit 9 acquires the position of the alignment mark indicated in 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 mark, thereby adjusting the pattern of laser light irradiated from the exposure head 41 onto the substrate S during the exposure operation. The control unit 9 then draws the pattern on the substrate S by causing the exposure head 41 to irradiate the substrate S with laser light modulated according to the pattern to be drawn.

The control unit 9 controls the operation of each of the above-mentioned units to perform various processes. To this end, the control unit 9 is equipped with a CPU (Central Processing Unit) 91, memory 92, storage 93, input 94, display unit 95, interface unit 96, and other components. The CPU 91 reads and executes a control program 931 previously stored in storage 93, and performs various operations described below. The memory 92 is used for calculation processing by the CPU 91, or stores data generated as a result of the calculation processing on a short-term basis. The storage 93 stores various data and control programs on a long-term basis. Specifically, in addition to the control program 931 executed by the CPU 91, the storage 93 also stores, for example, CAD (Computer Aided Design) data 932, which is design data representing the content of the pattern to be drawn.

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

By executing the control program 931, the CPU 91 realizes 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. Note that each of these functional blocks may be realized, at least in part, by dedicated hardware.

The exposure data generation unit 911 generates exposure data 911 for modulating the light beam according to the pattern, based on the CAD data 932 read from the storage 93. If the substrate S is deformed, such as distorted, the exposure data generation unit 911 corrects the exposure data according to the amount of distortion of the substrate S, making it possible to draw according to the shape of the substrate S. The exposure data is sent to the exposure head 41, which modulates the laser light emitted from the light irradiation unit 40 according to the exposure data. The modulated light beam modulated according to the pattern is thus irradiated onto the substrate S, and the surface of the substrate S is partially exposed to draw the pattern.

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

The stage control unit 914 controls the stage drive mechanism 3 to move the stage 2 for alignment adjustment and for scanning movement 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 movement, a main scanning movement in which the stage 2 is moved in the Y direction at a constant speed to pass the substrate S below the exposure head 41 is combined with a step feed (sub-scanning movement) in the X direction at a constant pitch.

Figure 3 is a diagram showing the configuration of the light irradiation unit. Figure 3(a) is a top view schematically showing the main components of the laser emission unit 43 and illumination optical system 44 of the light irradiation unit 40, and Figure 3(b) is a side view thereof. Figure 3(c) is a diagram illustrating the intensity distribution of the laser light beam emitted from the light irradiation unit 40. Note that the basic structure of the light irradiation unit 40 shown below is the same as that described in Patent Document 1. For this reason, Patent Document 1 should be referred to for detailed structure and operating principles, and only a brief explanation of the main components will be given here.

As shown in Figure 3(a), the laser emission unit 43 has multiple light source units 430. Here, five sets of light source units 430 are used, but the number of light source units is not limited to this and can be any number.

Each light source unit 430 has a laser light source 431 that emits laser light, a collimator lens 432, and a shutter 433. The laser light source 431 is, for example, a laser diode that outputs laser light of a predetermined wavelength. The collimator lens 432 converts the laser light emitted from the laser light source 431 into collimated light.

The shutter 433 is controlled by the light source driver 42 to mechanically open and close the optical path of the collimated light. Specifically, as shown in FIG. 3(b), the shutter 433 is moved by an opening and closing mechanism (not shown) between a blocking position (dotted line) where it blocks the optical path of the collimated light, and a passing position (solid line) where it retreats from the optical path of the collimated light and allows the collimated light to pass. In this example, the shutter 433 moves in the vertical direction (Z direction). Details will be described later, but in normal use the shutter 433 is positioned in the passing position.

The light source units 430 are arranged side by side in the X direction so that the optical axes of each light source unit 430, indicated by the two-dot chain lines, are contained in the same horizontal plane (XY plane). The optical axes of each light source unit 430 intersect at a single point.

A segmented lens 441 of the illumination optical system 44 is positioned at a position corresponding to this intersection. The segmented lens 441 is a so-called cylindrical lens array (or cylindrical fly's eye lens) in which multiple element lenses having power only in the X direction are arranged. As described in Patent Document 1, the segmented lens section 441 outputs the laser light incident on its (-Y) side end face from each light source unit 430 as a light beam that spreads in the X direction from its (+Y) side end face. As a result, the laser light emitted from each of the multiple laser light sources 431 is combined and output as a single laser light beam. This makes it possible to obtain a high-intensity exposure beam.

The combined laser light beam passes through two cylindrical lenses, specifically, cylindrical lens 442, which has power only in the X direction, and cylindrical lens 443, which has power only in the Z direction, in that order. This shapes the laser light beam L into a light beam with a flat beam spot shape that is wide in the X direction and narrow in the Z direction, a so-called line beam.

If the light-receiving surface were placed at the position indicated by the dashed line in Figure 3(a), a beam spot that is long in the X direction and short in the Z direction would appear on the light-receiving surface, as shown in the upper right diagram. In this case, it is desirable for the light intensity I on the light-receiving surface to have a narrow Z direction and a wide, uniform distribution in the X direction, as shown in Figure 3(c).

A detection unit 440 is provided on the optical path of the laser light beam L to detect its intensity. The detection unit 440 includes a beam splitter 444 provided immediately before the splitting lens 441 in the direction of light travel, and a photodetector 445 that receives the light split from the laser light beam L by the beam splitter 444.

The location of the detector 440 is not limited to this example, and it can be placed at any appropriate position on the optical path as long as it is capable of detecting the intensity of the laser light beam L. In other words, it can be placed at any position on the optical path after the laser light from each light source unit 430 is combined and before it is modulated by the optical modulator described below. For example, it may be placed behind the split lens 441 in the direction of light travel. However, in order to obtain a clear image on the exposed surface of the substrate S, it is more preferable to place it on the optical path before it is beam shaped by various optical elements.

For this reason, in this embodiment, the detection unit 440 is positioned immediately before the split lens 441, under the assumption that all light emitted from each light source unit 430 is incident on the detection unit 440. At this position, it cannot be said that the light from all light source units 430 is completely combined; however, by determining in advance the correspondence between the amount of light detected here and the amount of light after combination, it is possible to perform detection with sufficient accuracy. For example, if the distance between the light source and the detection unit 440 is increased, the light from each light source unit 430 will become closer to parallel light overall, improving detection accuracy; however, it should be noted that this may result in a problem in that the dimensions of the light irradiation unit 40 will become larger.

The detection unit 440 is provided for the purpose of detecting the beam width Ws (Figure 3(c)) in the minor axis direction of the beam spot of the laser light beam L, i.e., in the Z direction. For example, light split by the beam splitter 444 can be received by a two-dimensional image sensor serving as a photodetector 445, and a two-dimensional image of the beam spot can be obtained. By determining in advance the correspondence between the beam spot shape at the detection position and the beam spot shape after shaping, the spot width Ws can be obtained from the obtained two-dimensional image. For example, a predetermined threshold value can be set for the light intensity I, and the width of the portion where the detected light intensity I exceeds the threshold value can be obtained.

In this embodiment, the laser light emitted from each light source unit 430 is expanded in the X direction to obtain a line beam, and the uniformity of the light intensity I in the X direction is ensured by using the illumination optical system 44 also described in Patent Document 2. This makes it possible to detect the spot width Ws representatively at an appropriate position in the X direction. In that sense, a one-dimensional image sensor with its longitudinal direction in the Z direction can also be used as the photodetector 445.

In addition, here, the laser light beam L is split by the beam splitter 444 and guided to the photodetector 445 for light detection, but any configuration that allows light detection in real time even during exposure operation is acceptable, and is not limited to the above example.

In this way, the light irradiation unit 40 generates a high-intensity laser light beam (line beam) L that extends long in the X direction, has uniform intensity, and has a short, flat spot shape in the Z direction, and guides this to the exposure head 41, which will be described next. At this time, the laser light beam L travels in the (+Y) direction.

Figure 4 is a schematic diagram showing an example of the detailed configuration of an exposure head. As shown in Figure 4, the exposure head 41 is provided with a spatial light modulator 410 having a diffractive optical element 411. Specifically, the spatial light modulator 410 is attached to the top of a support 400 that extends in the vertical direction (Z direction) of the exposure head 41. The spatial light modulator 410 is supported by the support 400 via a movable stage 412 with the reflective surface of the diffractive optical element 411 facing downward.

In the exposure head 41, the diffractive optical element 411 is positioned so that the normal to its reflecting surface is tilted relative to the direction of travel of the incident light beam L. Light emitted from the illumination optical system 53 enters the mirror 413 through an opening in the support 400, is reflected by the mirror 413, and then is irradiated onto the diffractive optical element 411. The state of each channel of the diffractive optical element 411 is then switched by the control unit 9 in accordance with the exposure data, and the laser light beam L incident on the diffractive optical element 411 is modulated.

The laser light reflected from the diffractive optical element 411 as zeroth-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, the diffractive optical element 411 is basically configured so that only the zeroth-order diffracted light reflected by the diffractive optical element 411 enters the projection optical system 414. The diffractive optical element 411 is positioned so that the zeroth-order diffracted light is emitted in the (-Z) direction.

Light passing through the lenses of the projection optical system 414 is converged by the focusing lens 415 and directed onto the substrate S at a predetermined magnification as a downward exposure beam traveling in the (-Z) direction. The projection optical system 414 constitutes a reduction optical system. This focusing lens 415 is attached to a focus drive mechanism 416. The focus drive mechanism 416 raises and lowers the focusing lens 415 in the vertical direction (Z-axis direction) in response to control commands from the focus control unit 913 of the control unit 9, thereby adjusting the convergence position of the exposure beam emitted from the focusing lens 415 on the top surface of the substrate S.

As shown along the optical path of the laser light beam L, indicated by the dashed dotted line in Figure 4, the laser light beam L guided from the light irradiation unit 40 to the exposure head 41 has a beam spot shape that is uniformly elongated in the X direction, with the X direction as the major axis and the Z direction as the minor axis. On the other hand, the modulated laser light beam Lm after modulation by the optical modulator 410 has the X direction as the major axis and the Y direction as the minor axis, and its intensity at each position 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 modulated laser light beam Lm reduced in both the X and Y directions. By directing the exposure beam Le, with its reduced spot size, onto the exposed surface of the substrate S, a fine pattern can be drawn on the surface of the substrate S.

By moving the exposure head 41 and the substrate S relative to each other in the Y direction while the exposure beam Le modulated according to the exposure data is incident on the substrate S, it is possible to expose a strip-shaped area of the substrate S that extends in the Y direction and has a width equivalent to the spot size of the exposure beam Le in the X direction. By repeatedly performing exposure while sequentially changing the relative position of the exposure head 41 and the substrate S in the X direction, it is possible to ultimately expose the entire substrate S.

In this way, by combining scanning movement in the Y direction and scanning movement in the X direction between the exposure head 41 and the substrate S, it is possible to perform drawing on the entire substrate S. In this specification, scanning movement in the Y direction is referred to as "main scanning movement," and the Y direction is referred to as the "main scanning direction Dm." On the other hand, scanning movement in the X direction is referred to as "sub-scanning movement," and the Y direction is referred to as the "sub-scanning direction Ds." In this embodiment, these scanning movements are achieved by moving the stage 2 supporting the substrate S relative to the fixed exposure head 41.

It is possible to provide multiple exposure units 4 with the above configuration at different positions in the X direction. In this embodiment, five sets of exposure units 4 with the same configuration are provided, and these emit exposure beams Le in parallel to perform drawing, thereby improving the throughput of the drawing process. Note that although these exposure units 4 can operate independently of each other, their scanning movement relative to the substrate S is structurally uniform.

Figure 5 is a flowchart showing the processing executed by the exposure apparatus configured as described above. This operation is realized by the CPU 91 of the control unit 9 executing a control program 931 pre-recorded in the storage 93, causing the above-mentioned components of the apparatus to perform predetermined operations.

When the substrate S to be exposed is set on stage 2 (step S101), alignment adjustment is performed to align the posture of the substrate S on stage 2 with the position of the drawing pattern (step S102). There are many well-known techniques for alignment adjustment, so a detailed description will be omitted here.

After alignment adjustment, the stage 2 is positioned at a predetermined drawing start position (step S103), and light detection by the detection unit 440 begins (step S104). Then, while the substrate S is moved in the main scanning direction relative to the exposure head 41, the exposure head 41 irradiates the substrate S with an exposure beam Le to perform drawing (exposure operation, step S105). The area exposed in one main scanning movement is referred to here as a "stripe." Furthermore, a series of processes for one substrate S is referred to as one "job."

The exposure operation continues until exposure of one stripe is complete (NO in step S106). When exposure of one stripe is complete (YES in step S106), it is determined whether processing of one job is complete (step S107). If processing is not complete (NO in step S107), that is, if unexposed areas remain, the stage S is stepped a predetermined pitch in the sub-scanning direction (X direction) (sub-scanning movement, step S108). Then, the process returns to step S105 and exposure operation for the next stripe is performed.

If processing for one job has been completed (YES in step S107), light detection by the detection unit 440 is completed (step S109), the processing result of the job is notified to the user (step S110), and the substrate S is unloaded (step S111). This completes processing for one substrate S. If the job has been completed successfully, a notification to that effect is issued in step S110.

Figure 6 is a schematic diagram explaining a job when multiple exposure heads are provided. As shown in Figure 6(a), when multiple exposure heads 41 (in this example, five sets identified by the reference symbols 41a, 41b, 41c, 41d, and 41e) are arranged in the X direction, the exposure area Re on the surface of the substrate S to be exposed is divided into five areas corresponding to these exposure heads 41a to 41e.

As shown in Figure 6(b), with one scanning movement of the substrate S in the main scanning direction Dm, each exposure head 41a, 41b, 41c, 41d, and 41e exposes one stripe's worth of regions R1a, R1b, R1c, R1d, and R1e, respectively. After the substrate S moves one step in the sub-scanning direction Ds, the next main scanning movement exposes new one stripe's worth of regions R2a, R2b, R2c, R2d, and R2e, respectively. This process is repeated until the entire exposure region Re has been exposed, completing one job.

In this way, the exposure apparatus 1 of this embodiment performs exposure operations in parallel using multiple exposure units 4, and each individual exposure unit 4 has multiple laser light sources 431 as the light source for the exposure beam Le. There is a risk that one of these laser light sources 431 may malfunction during the exposure operation.

For example, the optical axis of one of the laser light sources 431 may become slightly misaligned due to temperature changes or vibrations of the device. In this case, the exposure beam Le may widen (increase in spot size), which may result in a decrease in drawing resolution. Also, one of the laser light sources 431 may deteriorate, reducing its light output or even ceasing to light up. In this case, the light intensity I of the combined laser light beam L may decrease (reduction in spot size), which may result in poor exposure. In this way, fluctuations in spot size have a significant impact on the quality of the drawing process results.

These fluctuations can be detected by monitoring the spot size of the laser light beam L in real time during the exposure operation. In this embodiment, the exposure control unit 912 of the control unit 9 constantly receives output from the detection unit 440 (steps S104 to S109) and monitors whether the spot width Ws of the laser light beam L is within a predetermined appropriate range. If it is detected that the spot width Ws is outside the appropriate range, an error state is determined, as there is a high probability that an abnormality has occurred in one of the laser light sources 431, and the error processing described below is executed as an interrupt process.

First, to illustrate the concept of error handling, we will explain the case where only one exposure unit 4 is installed. When an abnormality occurs in one of the laser light sources 431, the simplest error handling method is to stop operation of the device. Naturally, this will result in a decrease in productivity, so it is necessary to minimize the period of operation downtime and to resume processing automatically whenever possible. The error handling described below meets these needs.

Figure 7 is a flowchart showing a first mode of error processing. This processing is executed as an interrupt processing when the control unit 9 detects, while the exposure operation is being performed, that the spot width Ws of the laser light beam L detected by the detection unit 440 is outside a predetermined appropriate range. The contents of the error processing can be stored in advance in the storage 93 as a control program 931.

First, an error log is recorded to indicate that there has been a fluctuation in the beam spot width (step S201). This allows the operator to grasp the operating status of the device after the fact. Furthermore, since there is no point in continuing the exposure operation while there is an abnormality in the exposure beam Le, the exposure operation in progress is interrupted and drawing is stopped (step S202). Drawing is stopped by stopping the irradiation of the exposure beam Le onto the substrate S and the movement of the substrate S by the stage 2.

If operation is to be stopped immediately as an error handling measure, the processing up to this point is sufficient. In this state, for example, an operator can perform inspections and maintenance work. On the other hand, the processing below is intended to adjust the exposure conditions so that drawing is possible depending on the current situation, allowing operation to be resumed as quickly as possible. The basic idea is to exclude the light source unit that caused the fluctuation in beam spot width (referred to here as the "abnormal light source") and form the exposure beam Le using only normal light source units, thereby making it possible to resume exposure.

First, processing is performed to identify the anomalous light source (step S203). As described above, fluctuations in the spot width Ws can be caused by an abnormality in one of the multiple light source units 430 (such as misalignment of the optical axis or fluctuations in the output light amount). Which light source unit 430 is the anomalous light source is identified.

Specifically, while the laser driving unit 42 supplies power to turn on the laser light sources 431 of all light source units 430, the shutter 433 is opened and closed so that only light from one light source unit 430 enters the detection unit 440. By changing the combination of open and closed states of the shutter 433 of each light source unit 430, it is possible to detect the light emitted from the laser light source 431 individually for each light source unit 430.

A light source unit 430 whose detected light intensity, position, spot size, etc. meet the specified values can be determined to be "normal," while a light source unit 430 whose detected light intensity, position, spot size, etc. do not meet the specified values can be determined to be an "abnormal light source." In this way, an abnormal light source is identified.

Next, for normal light source units 430, the shutter 433 is positioned at the passing position to allow the laser light emitted from the laser light source 431 to pass, while for light source units 430 determined to be abnormal light sources, the shutter 433 is positioned at the blocking position to block the laser light (step S204). This excludes abnormal light sources, and only the laser light emitted from normal light source units 430 is combined to form the laser light beam L.

In this case, changes in the light source configuration will cause fluctuations in the intensity and uniformity of the combined laser light beam. The fluctuations in uniformity can be addressed by calibrating the spatial light modulator 410 (step S205). This calibration manipulates the operating parameters of the spatial light modulator 410 to adjust the intensity of the diffracted light emitted from the diffractive optical element 411 for each position, thereby achieving uniformity of the beam intensity in the X direction. For example, the voltage applied to the light modulation element that constitutes the spatial light modulator can be the operating parameter to be manipulated.

In this case, the calibration process described in JP 2016-139074 A, previously disclosed by the applicant of the present application, can be applied, for example. Furthermore, this is not limited to this, and various adjustment methods can be applied that can generate a line beam that is narrow in the minor axis direction and has uniform intensity in the major axis direction using only a normal light source unit 430. Therefore, a description of the calibration process will be omitted here.

Furthermore, a decrease in light intensity due to a reduction in the number of light source units 430 used is addressed by changing the main scanning speed (step S206). That is, since a decrease in the overall light amount in the exposure beam Le causes insufficient exposure on the substrate S, the necessary exposure amount is ensured by slowing down the main scanning speed. Specifically, the main scanning speed can be changed and set according to the changed light amount so that the product of the light amount and the exposure time remains constant.

By resetting the exposure conditions in this way (adjusting the light intensity and main scanning speed), drawing can be resumed under the new exposure conditions (step S207). This exposure operation will be referred to as the "continuous production mode" here to distinguish it from the normal operating mode. In continuous production mode, the main scanning speed is slower than normal, so drawing takes longer. This results in a slight decrease in productivity, but the same level of drawing quality as normal operation can be maintained.

If such an abnormality occurs during a job and error processing is performed, a notification to that effect is issued in step S110 (Figure 5). In addition to the fact that an abnormality occurred during job execution, the notification may include, as appropriate, information based on the recorded error log, such as the location on the substrate S where the abnormality occurred, information about the identified abnormal light source, and information about the changed exposure conditions.

So far, we have explained error handling when focusing on only one set of exposure units 4. However, in a configuration where multiple exposure units 4 are used to perform drawing in parallel, if an abnormality occurs in one of the exposure units 4, it is not necessarily desirable to stop drawing on the exposure units 4 that are not experiencing abnormalities. This is because if operation is stopped even though drawing is being performed normally, the board in the middle of drawing will be deemed a defective product.

For example, one possible response would be to stop exposure operations for the exposure unit 4 in which the abnormality occurred, while continuing normal exposure operations for the other exposure units 4. In this case, for the exposure area on the surface of the substrate S where the abnormality occurred, the area after the abnormality occurs becomes an invalid area that is not exposed. On the other hand, for the area where the normal exposure unit 4 is responsible for exposure operations, drawing is completed normally across the entire area.

In contrast, it may be desirable to resume drawing on an exposure unit 4 that has experienced an abnormality by changing the exposure conditions, as in the first mode of error processing. This is because doing so can minimize substrate loss. The second mode of error processing, described below, takes this into consideration.

Figure 8 is a flowchart showing the second mode of error handling. The basic concept of error handling is the same as the first mode, but some processing has been changed due to the fact that multiple exposure units 4 are operating in parallel. This error handling is executed as an interrupt process when an abnormality in the beam spot width is detected in at least one of the multiple exposure units 4.

As with the first aspect, when an abnormality in the beam spot width is detected in any of the exposure units 4, an error log is first recorded (step S301). However, because no abnormality is detected in the other exposure units 4, operation is not immediately halted; instead, processing is initiated to identify the abnormal light source for the exposure unit 4 where the abnormality occurred (step S302). After the abnormality occurs, the drawing process is halted when one stripe or job is completed (steps S303 and S304).

If operation is stopped while processing one stripe, the drawing results will be invalid even if there is no abnormality in the exposure unit 4. If drawing is stopped after processing of one stripe or after one job is completed, this situation can be avoided. Furthermore, when processing is resumed, drawing can be performed from the beginning of a new stripe. Therefore, in an exposure unit 4 that is not experiencing any abnormalities, it is possible to properly draw the entire exposure area that the exposure unit 4 is to expose.

For the exposure unit 4 in which an abnormality has occurred, the abnormal light source is identified (step S302), calibration is performed by blocking the abnormal light source (steps S305 and S306), and the main scanning speed is changed (step S307), as in the first mode. This makes it possible to perform drawing processing in "continuous production mode" with the changed exposure conditions.

Meanwhile, with the change in main scanning speed, calibration is also performed on each of the normal exposure units 4 (step S308). That is, by reducing the output light amount according to the newly set main scanning speed, the same exposure amount is ensured before and after the speed change. In this way, calibration is performed on each exposure unit 4, and a new main scanning speed is set, allowing drawing to resume in continuous production mode with a reduced main scanning speed (step S309).

By changing the exposure conditions in this way and resuming drawing, it is possible to shorten the downtime and minimize the decline in productivity. Furthermore, the areas of the substrate S that cannot be exposed normally and are therefore invalid are kept to a minimum.

In step S110 (Figure 5) after drawing resumes, similar to the error processing of the first aspect, the information can include, as appropriate, the fact that an abnormality occurred during job execution, information about the exposure unit where the abnormality occurred, the position on the substrate where the abnormality occurred, information about the identified abnormal light source, information about the changed exposure conditions, etc.

It would also be convenient if, for exposure units 4 where no abnormalities have occurred, a notification could be issued that allows the user to distinguish between the portions of the exposure area where the exposure unit 4 was responsible for the exposure operation that were exposed in normal operation mode and the portions that were exposed in continuous production mode. This is because, although both were exposed at the specified exposure amount, it cannot be said that changes in exposure conditions may have had some effect on the drawing quality. For example, such a notification could be issued using the following GUI (Graphical User Interface) screen.

Figure 9 shows an example of the GUI screen after an abnormality has occurred. The figure shows a schematic representation of the surface of the substrate S, with areas exposed in normal operation mode, areas exposed in production continuation mode, and invalid areas that were not properly exposed colored differently to make them easily identifiable. Here, we assume that an abnormality has occurred in one of the five exposure units 4, including the exposure head 41a, during drawing using main scanning movement in the (-Y) direction. Furthermore, we assume that sub-scanning movement has been performed in the (+X) direction.

Figure 9(a) shows an example in which exposure is stopped only for the abnormal exposure unit 4, while normal exposure units 4 continue drawing without changing the exposure conditions. In the exposure region R3a on the surface of the substrate S exposed by the exposure head 41a of the abnormal exposure unit 4, the exposure position when the abnormality occurred is indicated by an "X" mark, and the region that was exposed normally before that point and the invalid region that was not exposed or not properly exposed after that point are shaded differently. On the other hand, the exposure regions R3b to R3e exposed by the other normal exposure units 4 are shown as regions that were exposed normally overall.

Figure 9(b) shows an example where normal operation mode is switched to continuous production mode midway through drawing. If an abnormality occurs at the position marked with an "X" while processing one stripe, the area of that stripe from the position where the abnormality occurred becomes an invalid area. However, the exposure conditions are readjusted and drawing resumes in continuous production mode, and the next stripe and beyond are colored differently to indicate that they were exposed in continuous production mode.

In the exposure areas R3b-R3e exposed by the other exposure units 4, drawing continues until processing of the stripe where the abnormality occurred is completed, so the entire stripe and any stripes exposed before it are shown as areas that were normally exposed. On the other hand, areas that were exposed in production continuation mode after calibration are colored to indicate this.

When a notification is given after the job is completed (step S110 in Figure 5), such a GUI screen is displayed, for example, on the display unit 95, allowing the operator to easily see the conditions under which the substrate S was drawn.

As explained above, in the exposure apparatus 1 of this embodiment, the laser light source 431 of the light source unit 430 functions as the "laser light source" of the present invention, while the spatial light modulator 410 functions as the "light modulator" of the present invention. The exposure unit 4 corresponds to the "exposure section" of the present invention. Furthermore, the photodetector 445 functions as the "light receiver" of the present invention, and the detection section 440, which includes this and the beam splitter 444, functions as the "detection section" of the present invention.

The control unit 9 also functions as the "control unit" of the present invention. In this embodiment, the stage 2 also functions as the "stage" of the present invention, and the stage movement mechanism 3 also functions as the "movement unit" of the present invention.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, each light source unit 430 is provided with a mechanically operable shutter 433, and for any light source unit 430 in which an abnormality has occurred, the shutter 433 is placed in the optical path to block light. This excludes that light source unit 430 from further operation. However, the method for excluding an abnormal light source unit is not limited to this. For example, the optical path may be optically bent to prevent the emitted light from entering the illumination optical system 44. It is also possible to shut off the power supply to the laser light source 431 to turn it off. However, this may cause temperature fluctuations in the other light source units, making their operation unstable. Therefore, it is more preferable to continue operating the laser light source while taking measures to prevent the emitted light from entering the illumination optical system 44.

For example, in the above description of the embodiment, several modes of error handling were described, including one that immediately stops operation. Any of these may be selected in advance and adopted depending on the purpose, or the user may select and execute one of these multiple modes via operational input.

Furthermore, for example, in the second mode of error processing in the above embodiment, calibration is also performed on the normal exposure unit 4 in conjunction with a change in the main scanning speed. In this case, since the scanning speed is simply changed in the normal exposure unit 4, if the relationship between the optimal values of the operating parameters of the spatial light modulator 410 and the scanning speed is determined in advance, it is possible to execute the production continuation mode by simply changing the parameters without performing calibration.

Furthermore, in the above embodiment, it is assumed that the exposure conditions can be readjusted through error processing, but in some cases, even if the exposure conditions are changed, it may not be possible to perform appropriate drawing. In such cases, it is possible to abandon resuming drawing and notify the user of this.

As explained above using specific exemplary embodiments, in the exposure apparatus and exposure method according to the present invention, the detection unit may, for example, include a beam splitter provided on the optical path that splits a portion of the laser light beam, and a light receiver that receives the split light from the laser light beam. With this configuration, fluctuations in the laser light beam can be detected in real time, and error processing can be immediately performed if fluctuations are detected.

Also, for example, during error processing, the exposure unit may be configured to generate laser light beams from the remaining laser light sources, excluding the one that has experienced an error, and change the exposure conditions according to the intensity of the laser light beam at that time. By excluding the laser light source that has experienced an error, the overall light intensity decreases. For this reason, it is thought that proper exposure cannot be performed under the same operating conditions as under normal conditions. By changing the exposure conditions according to this change in light intensity, it becomes possible to resume exposure under new exposure conditions.

In this case, error processing may be configured, for example, to have the detection unit individually detect the laser light emitted from each laser light source and identify the laser light source in which the error occurred based on the detection results. With this configuration, it is possible to individually detect the light from each laser light source even on the optical path after laser light from multiple laser light sources has been combined.

Furthermore, for example, in a configuration that includes a stage that supports the substrate and a moving unit that moves the exposure unit and the stage relative to each other to change the incident position of the exposure beam on the substrate, the movement speed of the relative movement by the moving unit may be changed as an exposure condition. With such a configuration, it is possible to ensure the specified exposure amount by compensating for changes in the amount of light with the movement speed.

For example, in a configuration in which the exposure unit has an optical modulator that modulates the laser light beam based on exposure data, the operating parameters of the optical modulator may be changed as an exposure condition. Techniques for manipulating the operating parameters of optical modulators to achieve uniformity in the intensity of the laser light beam are well known, and this technique can also be applied to the present invention to adjust the exposure conditions.

Furthermore, for example, in a configuration with multiple exposure units that perform drawing on a single substrate in parallel, when changing the exposure conditions for one exposure unit, the exposure conditions for the other exposure units may also be changed. With this configuration, it is possible to adjust exposure conditions such as the relative movement speed between the exposure unit and the substrate, where a change in one exposure unit affects the other exposure units.

Furthermore, for example, in a configuration with multiple exposure units that perform drawing on a single substrate in parallel, when error processing is performed on one exposure unit, drawing on the substrate can be continued without changing the exposure conditions for the other exposure units. With this configuration, the other exposure units that are not in an error state can continue to perform the same processing as before, minimizing the loss of productivity that occurs when operations are stopped.

For example, the laser light beam may be a line beam, and the spot size may be detected as the width of the line beam in the minor axis direction. Since the width of the line beam is a parameter related to the resolution in drawing, detecting fluctuations in the width and performing error processing can avoid the problem of drawing continuing at a reduced quality.

The exposure method according to the present invention may also be configured to resume drawing by applying the exposure conditions changed by error processing, for example. If the exposure conditions are changed so that appropriate exposure can be performed even when a laser light source in an error state is included, then by applying the changed exposure conditions, it is possible to continue drawing while suppressing degradation of drawing quality.

In particular, when drawing is performed while moving the exposure unit emitting the laser light beam relative to the substrate, the relative movement speed between the exposure unit and the substrate may be configured to be slower than the original speed when drawing is resumed after the error laser light source is removed. Although the overall light intensity will decrease when the error laser light source is removed, the effective exposure amount can be maintained at the specified value by slowing down the relative movement speed between the exposure unit and the substrate and lengthening the exposure time.

This invention is suitable for technical fields such as exposing substrates to form patterns on substrates such as semiconductor substrates, printed wiring boards, and glass substrates.

1 Exposure device 2 Stage 3 Stage movement mechanism (moving part)
4 Exposure unit (exposure section)
9 Control unit 410 Spatial light modulator (light modulator)
430 Light source unit 431 Laser light source 440 Detector 444 Beam splitter 445 Photodetector (photoreceiver)
L: Laser light beam Le: Exposure beam S: Substrate

Claims (14)

an exposure unit having a plurality of laser light sources, which combines laser light beams emitted from the plurality of laser light sources to generate a single laser light beam, modulates the laser light beam based on exposure data, and irradiates the laser light beam as an exposure beam onto a substrate to be exposed, thereby drawing;
a detection unit that detects the laser light beam on an optical path of the laser light beam;
a control unit that controls exposure conditions for the substrate,
The control unit executes a predetermined error process when the spot size of the laser light beam detected by the detection unit during the execution of the drawing is outside a predetermined appropriate range. The exposure apparatus of claim 1, wherein the detection unit includes a beam splitter provided on the optical path to split a portion of the laser light beam, and a light receiver that receives the split light from the laser light beam. The exposure device described in claim 1 or 2, wherein, in the error processing, the control unit causes the exposure unit to generate the laser light beam using the remaining laser light sources excluding the one in which the error occurred, and changes the exposure conditions according to the intensity of the laser light beam at that time. The exposure device described in claim 3, wherein, in the error processing, the control unit causes the detection unit to individually detect the laser light emitted from each of the laser light sources, and identifies the laser light source in which the error occurred based on the detection results. a stage for supporting the substrate;
a moving unit that moves the exposure unit and the stage relative to each other to change the incident position of the exposure beam on the substrate,
5. The exposure apparatus according to claim 1, wherein the control unit changes a movement speed in the relative movement by the movement unit as the exposure condition. the exposure unit has an optical modulator that modulates the laser light beam based on the exposure data,
6. The exposure apparatus according to claim 1, wherein the control unit changes an operating parameter of the optical modulator as the exposure condition. a plurality of exposure units that perform the drawing on one of the substrates in parallel with one another;
7. The exposure apparatus according to claim 1, wherein when the control unit changes the exposure conditions for one of the exposure units, the control unit also changes the exposure conditions for the other exposure units. a plurality of exposure units that perform the drawing on one of the substrates in parallel with one another;
7. The exposure apparatus according to claim 1, wherein when the control unit performs the error processing for one of the exposure units, the control unit continues the drawing on the substrate without changing the exposure conditions for the other exposure units. An exposure apparatus according to any one of claims 1 to 8, wherein the laser light beam is a line beam, and the spot size is detected as the width of the line beam in the minor axis direction. 1. An exposure method in which laser beams emitted from a plurality of laser light sources are synthesized to generate a single laser light beam, and the laser light beam is modulated based on exposure data and irradiated onto a substrate to be exposed as an exposure beam for drawing, comprising:
an exposure method for detecting the laser light beam on an optical path of the laser light beam, and performing a predetermined error process when a spot size of the laser light beam detected during the execution of the drawing is outside a predetermined appropriate range; The exposure method described in claim 10, wherein the error processing involves generating the laser light beam from one of the plurality of laser light sources other than the one in which the error occurred, and changing the exposure conditions according to the intensity of the laser light beam at that time. The exposure method described in claim 11, wherein the error processing involves individually detecting the laser light emitted from each of the multiple laser light sources and identifying the laser light source in which an error has occurred based on the detection results. The exposure method described in claim 11 or 12, wherein the changed exposure conditions are applied and the drawing is resumed. 14. The exposure method according to claim 13, wherein the drawing is performed while moving an exposure unit that emits the laser light beam and the substrate relatively.
In the exposure method, the relative movement speed between the exposure unit and the substrate is reduced from the original speed during the resumption of the drawing.