JP7795313B2 - Direct imaging exposure apparatus and stage cleaning method for direct imaging exposure apparatus - Google Patents

Description

The invention of this application relates to a direct imaging exposure device that forms an exposure pattern using a spatial light modulator and then exposes the pattern.

Direct imaging exposure devices are known as exposure devices used in photolithography processes, etc. Direct imaging exposure devices are a type of maskless exposure device that forms an exposure pattern using a spatial light modulator such as a DMD (Digital Mirror Device) to directly draw and expose the pattern without a mask.
Direct imaging exposure devices are extremely easy to change the exposure pattern as needed, making them suitable for small-lot production of a wide variety of products. For this reason, they are widely used for manufacturing circuit boards for various products and for manufacturing various micro-components (MEMS). While the object to be exposed is often a plate (substrate), it can also be non-plate-shaped.

JP 2009-300543 A

In such direct imaging exposure apparatuses, there is a problem in that exposure quality is reduced due to the inclusion of foreign matter such as dust and dirt (hereinafter collectively referred to as "dust"). This type of exposure apparatus is installed in a clean room where the required level of cleanliness is maintained, and clean air is blown down inside the apparatus to prevent dust from being transferred to the substrate.
However, it is difficult to completely eliminate dust inside the equipment, which is an obstacle to improving exposure quality. One of the causes of dust is that the substrate itself brings dust into the equipment.

Substrates are often cleaned with a down-blow of clean air before being loaded into the equipment, but even so, dust can easily be carried into the equipment if it adheres to the backside of the substrate or the handle that transports the substrate. Dust can also be generated when part of the substrate is chipped or when chips occur in structures such as thin films formed in previous processes.

To remove such dust and prevent deterioration of exposure quality, a sticky roller is sometimes used. The sticky roller is brought into contact with the substrate or the stage on which the substrate is placed and rolled, transferring and removing the dust before exposure.
While dust removal using such adhesive rollers is effective to a certain extent, there is a problem in that it cannot sufficiently remove dust from uneven surfaces such as uneven surfaces or steps. For example, if there is dust at the step between the edge of the substrate placed on the stage and the stage (the step is the thickness of the substrate), it cannot be transferred to the adhesive roller properly and the dust tends to remain. Also, if the substrate has uneven surfaces or through holes, it is often the case that dust cannot be removed using only an adhesive roller.

Furthermore, even if dust on the substrate or its edges can be removed, it cannot be removed from the surface of the stage that is covered by the substrate (the backside of the substrate). It would be possible to remove the substrate from the stage and roll it over the stage with an adhesive roller, but the stage also has uneven surfaces created by vacuum suction to hold the substrate, and any dust that gets caught in these uneven surfaces cannot be removed with an adhesive roller. For example, if dust gets into a vacuum suction hole and is accidentally released, it could be transferred during exposure, causing a loss of exposure quality.

The invention of this application was made to solve the above-mentioned problems with direct imaging exposure devices, and aims to enable sufficient dust removal even when the surface of a substrate or stage is uneven, thereby improving exposure quality.

In order to solve the above problems, this specification discloses a direct imaging exposure apparatus that forms an exposure pattern using a spatial light modulator and exposes a substrate.
This device is
an exposure head including a light source and a spatial light modulator;
a stage on which a substrate is placed;
The stage moving mechanism moves the stage so that the substrate passes through an irradiation area, which is an area irradiated with light of an exposure pattern by the exposure head.
In this direct imaging exposure device,
a dust suction means for removing dust adhering to the stage or the substrate placed on the stage by suction using negative pressure;
The dust suction means includes a nozzle having a long slit and a suction source connected to the nozzle,
the nozzle is positioned a predetermined distance above the stage or the substrate placed on the stage;
The nozzle is provided so that its length is in the horizontal direction perpendicular to the direction of movement of the stage.
In order to solve the above problem, in a direct imaging exposure apparatus, the nozzle may be provided with a nozzle position adjustment mechanism that adjusts the distance from the stage or the substrate placed on the stage to a predetermined distance.
In order to solve the above problems, a direct imaging exposure apparatus is provided,
a rangefinder is provided to measure the distance of the stage or the substrate relative to a reference height;
The nozzle position adjustment mechanism may be configured to include a vertical drive source that moves the nozzle up and down to adjust the position in accordance with the data measured by the range finder.
In order to solve the above problems, a direct imaging exposure apparatus is provided.
The exposure head includes a projection lens that projects the formed exposure pattern onto an irradiation area;
an autofocus rangefinder is provided to measure the distance to the surface of the substrate in order to focus the projection of the exposure pattern by the projection lens;
The rangefinder may also be used as an autofocus rangefinder.
In order to solve the above problems, a direct imaging exposure apparatus is provided,
A brush made of elastic wire is provided,
When the stage is moved by the stage moving mechanism, the brush comes into contact with the stage or the substrate on the stage, causing the wire to bend;
The nozzle may be configured to be located at a position where it can suck up dust scraped off by the wires of the brush while the stage is being moved by the stage moving mechanism.
In addition, in order to solve the above problem, in a direct imaging exposure apparatus, the brush may be capable of entering a groove or hole in the stage in a bent state when the stage is moved by a stage movement mechanism, or may be capable of abutting against a step between the stage and the substrate.
In order to solve the above problem, in a direct imaging exposure device, the nozzle may have a shape that covers the brush except for the tip of the wire.
In order to solve the above problem, the direct imaging exposure apparatus may have a configuration in which the nozzle is conductive and grounded.
In order to solve the above problems, a direct imaging exposure apparatus is provided,
A control unit is provided to control the stage moving mechanism and the dust collecting means,
The control unit is equipped with a main sequence program.
The main sequence program may be configured to perform a predetermined number of exposure processes in which a substrate is placed on the stage and the stage is moved by the stage movement mechanism, and then to perform stage cleaning in which dust is sucked and removed by positioning the nozzle a predetermined distance above the stage with no substrate placed on the stage and moving the stage by the stage movement mechanism.
In order to solve the above problems, this specification also discloses a stage cleaning method for a direct imaging exposure apparatus. This method is a method for cleaning the stage in a direct imaging exposure apparatus that includes an exposure head including a light source and a spatial light modulator, a stage on which a substrate is placed, and a stage movement mechanism that moves the stage so that the substrate passes through an irradiation area that is an area irradiated with light of an exposure pattern by the exposure head, and that forms a light pattern by the spatial light modulator to expose the substrate.
This stage cleaning method involves positioning a nozzle, which has a long horizontal slit perpendicular to the direction of stage movement by the stage movement mechanism and is connected to a suction source, a predetermined distance above the stage with no substrate placed on it, and then moving the stage by the stage movement mechanism in this state to suck up and remove dust adhering to the stage.

As explained below, in the direct imaging exposure apparatus according to the disclosed invention, dust is sucked and removed by the nozzle, thereby avoiding the problem of exposure quality degradation due to dust. In this case, the nozzle can also remove dust that has gotten into grooves and holes in the stage, so dust that could not be removed by an adhesive roller can be sufficiently removed. This is therefore highly effective in improving exposure quality. The same applies to removing dust from a substrate; dust adhering to the step between the substrate and the stage and dust that has gotten into recesses and through-holes in the substrate can be sufficiently removed, preventing this dust from being accidentally released and degrading exposure quality.
Furthermore, in a configuration in which a nozzle position adjustment mechanism is provided to maintain a predetermined distance between the nozzle and the stage or the substrate placed on the stage, an optimal suction force can be applied to the stage or the substrate, thereby optimizing dust collection.
Furthermore, in a configuration in which the autofocus rangefinder is also used to measure the vertical position of the stage or substrate relative to the reference height, the structure is simplified and costs can be reduced by reducing the number of parts.
Furthermore, in a configuration in which a brush is provided that contacts the stage or the substrate on the stage, causing the wire to bend, and the brush is positioned so that it can suck up dust scraped off by the wire, even tightly adhered dust can be sucked up and removed, thereby enhancing the effect of improving exposure quality.
In this case, if the brush wires are able to enter the grooves or holes in the stage in a bent state, or to abut against the step between the stage and the substrate, it is possible to more effectively remove dust that has entered the grooves, holes, or steps that could not be removed by dust removal with an adhesive roller, thereby further improving the effect of improving exposure quality.
Furthermore, in a configuration in which the nozzle covers the brush except for the tip of the wire, the dust scraped off by the brush can be sucked in and removed more effectively, further improving the exposure quality.
Furthermore, in a configuration in which the brush is a charge-removing brush, dust that is electrostatically attracted can also be removed reliably, and in this respect the effect of improving exposure quality is further enhanced.
Furthermore, according to an apparatus or method that performs the exposure process a predetermined number of times, and then positions the nozzle a predetermined distance above the stage without placing a substrate on it, and moves the stage using a stage movement mechanism to suck up and remove dust, it is possible to improve exposure quality without significantly reducing productivity, and since dust can be sucked up from the surface of the stage that was covered by the substrate, the effect of improving exposure quality is even greater in this respect.

1 is a schematic front view of a direct imaging exposure apparatus according to a first embodiment. 1 is a schematic side view of a direct imaging exposure apparatus according to a first embodiment. 1 is a schematic plan view of a direct imaging exposure apparatus according to a first embodiment. FIG. 2 is a schematic diagram showing the internal structure of the exposure head. FIG. 2 is a perspective schematic diagram showing an irradiation area. 10A and 10B are schematic front views showing adjustment of nozzle positions by a nozzle position adjustment mechanism. 5A to 5C are schematic front views showing the dust suction operation in the device of the first embodiment. FIG. 10 is a schematic side view showing an example in which two vertical drive sources are independently controlled. FIG. 10 is a schematic front view of the main part of a direct imaging exposure device according to a second embodiment. FIG. 10 is a schematic side view of the main part of a direct imaging exposure apparatus according to a second embodiment. 10 is a front schematic view showing the operation of the dust suction means in the second embodiment. FIG. FIG. 10 is a schematic front view showing the main parts of a direct imaging exposure device according to a third embodiment. FIG. 10 is a schematic side view showing the main parts of a direct imaging exposure apparatus according to a third embodiment.

Hereinafter, modes (embodiments) for carrying out the invention of this application will be described.
1 to 3 are schematic diagrams of a direct imaging exposure apparatus according to a first embodiment, with FIG. 1 being a schematic front view, FIG. 2 being a schematic side view, and FIG. 3 being a schematic plan view.
1 and 2 is a direct imaging exposure apparatus that forms a light pattern using a spatial light modulator to expose a substrate. Specifically, this apparatus includes an exposure head 1 including a light source and a spatial light modulator, a stage 6 on which a substrate W is placed, and a stage movement mechanism 61.

The exposure head 1 is cylindrical overall, positioned vertically, and emits light downward. Figure 4 is a schematic diagram showing the internal structure of the exposure head. As shown in Figure 4, the exposure head 1 includes a light source 2, a spatial light modulator 3 that spatially modulates the light from the light source 2, and an optical system (hereinafter referred to as the projection optical system) 4 that projects an image formed by the light modulated by the spatial light modulator 3.

The light source 2 used is one that outputs light of the optimum wavelength depending on the photosensitive wavelength of the photosensitive layer on the substrate W. Resist films are often sensitive to wavelengths ranging from the short visible wavelength range to the ultraviolet range, so the light source 2 used is one that outputs light in the short visible wavelength range to the ultraviolet range, such as 405 nm or 365 nm. Furthermore, to maximize the performance of the spatial light modulator 3, it is preferable for the light source 2 to output coherent light, and for this reason a laser light source 2 is preferably used. For example, a gallium nitride (GaN) semiconductor laser is used.

In this embodiment, a DMD is used as the spatial light modulator 3. As shown enlarged in Figure 4, in a DMD, each pixel is a tiny mirror 31. The mirrors (hereinafter referred to as pixel mirrors) 31 are, for example, square mirrors measuring approximately 13.68 μm on each side, and a large number of pixel mirrors 31 are arranged in a rectangular lattice pattern. The number of mirrors arranged is, for example, 1024 x 768.

The spatial light modulator 3 includes a modulator controller 32 that controls each pixel mirror 31. The exposure apparatus of this embodiment includes a main controller 7 that controls the entire apparatus. The modulator controller 32 controls each pixel mirror 31 in accordance with signals from the main controller 7. Each pixel mirror 31 uses the plane on which the pixel mirrors 31 are arranged as a reference plane, and can take a first attitude along this reference plane and a second attitude inclined at, for example, approximately 11 to 13 degrees relative to this reference plane. The first attitude is the off state, and the second attitude is the on state.
The spatial light modulator 3 includes a drive mechanism for driving each pixel mirror 31, and the modulator controller 32 can independently control whether each pixel mirror 31 takes the first position or the second position. Such a spatial light modulator 3 is available from Texas Instruments.

As shown in Figure 4, the exposure head 1 is equipped with an illumination optical system 5 that illuminates the spatial light modulator 3 with light from the light source 2. In this embodiment, the illumination optical system 5 includes an optical fiber 51. In order to form an image with higher illuminance, one exposure head 1 is equipped with multiple light sources 2, and an optical fiber 51 is provided for each light source 2. For example, a quartz-based multimode fiber is used as the optical fiber 51.

To form a precise image using the DMD spatial light modulator 3, it is desirable to make parallel light incident on each pixel mirror 31 and have it reflected by each pixel mirror 31, and it is also desirable to make the light incident on each pixel mirror 31 at an angle. For this reason, as shown in Figure 4, the illumination optical system 5 includes a collimator lens 52 that converts the diverging light emitted from each optical fiber 51 into parallel light.

The projection optical system 4 is composed of two projection lens groups 41, 42 and a microlens array (hereafter abbreviated as MLA) 43 positioned between the projection lens groups 41, 42. The MLA 43 is positioned as an auxiliary element to enable exposure with higher shape accuracy. The MLA 43 is an optical component consisting of a large number of tiny lenses arranged in a rectangular lattice pattern. Each lens element corresponds one-to-one to each pixel mirror 31 of the spatial light modulator 3.

In the exposure head 1 described above, light from the light source 2 is guided by the optical fiber 61 and then incident on the spatial light modulator 3 by the irradiation optical system 5. At this time, each pixel mirror 31 of the spatial light modulator 3 is controlled by the modulator controller 32 and selectively tilted in accordance with the exposure pattern. That is, in accordance with the exposure pattern to be formed, pixel mirrors 31 located at positions where light should reach the irradiation area are turned on, and other pixel mirrors 31 are turned off. Light reflected by pixel mirrors 31 in the off state does not reach the irradiation area, and only light reflected by pixel mirrors 31 in the on state reaches the irradiation area. As a result, light of a predetermined exposure pattern is irradiated onto the irradiation area.
A plurality of such exposure heads 1 are provided. As shown in Figure 3, in this embodiment, eight exposure heads 1 are provided. The eight exposure heads 1 form a single exposure pattern as a whole. Each exposure head 1 has the same configuration.

The stage 6 is a member on whose horizontal upper surface the substrate W is placed. The upper surface is provided with vacuum suction holes (not shown) that vacuum-suck the substrate W. The stage moving mechanism 61 is a mechanism that moves the stage 6 on which the substrate W is placed through the irradiation area.
The stage movement mechanism 61 includes a linear guide 60 arranged throughout the irradiation area, and a drive source (not shown) that moves the stage 6 linearly along the linear guide 60. A linear motor, for example, is used as the drive source, and a linear motor stage 6 configuration can be adopted. The direction in which the linear guide 60 extends is the transport direction. Hereinafter, this direction will be referred to as the X direction, and the horizontal direction perpendicular to the X direction will be referred to as the Y direction.
In addition, a standby position for the stage 6 is set on one side away from the irradiation area in the transport direction. A transfer mechanism (not shown) is disposed at the standby position.

The irradiation area will be further explained with reference to Fig. 5, which is a perspective schematic diagram showing the irradiation area. In Fig. 5, an area E (hereinafter referred to as an individual area) onto which light can be irradiated by one exposure head 1 is indicated by a square frame. A collection of individual areas E constitutes the irradiation area.
5 (X direction), the substrate W is irradiated with light at each individual area E. At this time, since the two rows of exposure heads 1 are arranged offset from each other, exposure is also performed without gaps in the horizontal direction (Y direction) perpendicular to the direction of movement.

As shown enlarged in Figure 5, each individual area E is actually a collection of tiny irradiation patterns (hereinafter referred to as "micropatterns") M. One micropattern M is a pattern created by one pixel mirror 31. The substrate W placed on the stage 6 moves through the irradiation area as the stage 6 moves, and the micropatterns M are turned on and off in a predetermined sequence in accordance with the timing of this movement. In this way, the desired exposure pattern is formed on the substrate W.

As shown in FIG. 1, the main controller 7 has a memory unit 71, which stores a main sequence program 72 for sequence control of the entire apparatus and a pixel sequence program 73 for sequence control of each pixel mirror 31 of the spatial light modulator 3 in each exposure head 1 when exposing one substrate W. The main sequence program 72 calls and executes the pixel sequence program 73 when exposing each substrate W. Note that since it is the modulator controller 32 that actually controls each pixel mirror 31, the pixel sequence program 73 is a program that provides a sequence to the modulator controller 32 so that each pixel mirror 31 is driven in accordance with that sequence.

Between the standby position and the irradiation area, a camera (not shown) is provided to capture images of the alignment marks on the substrate W in order to control (align) the formation position of the exposure pattern on the substrate W. The image data captured by the camera is sent to the main controller 7. The main controller 7 controls the formation position of the exposure pattern by executing a pixel sequence program 73 using the image data as an argument.

In order to improve exposure quality, the direct imaging exposure apparatus of this embodiment is equipped with a dust removal means of a different type than conventional ones. That is, the apparatus of the embodiment is equipped with a dust collection means that sucks and removes dust. The dust collection means is a means for sucking and removing dust adhering to the stage 6 or the substrate W on the stage 6 by using negative pressure.
1, the dust suction means includes a nozzle 81 having a slit 810 and a suction source 82 connected to the nozzle 81. A blower suction machine such as a ring blower can be used as the suction source 82. The negative pressure created by the suction source 82 is, for example, about -5 kPa to -20 kPa relative to atmospheric pressure.

2 and 3, the nozzle 81 is a long member that has a slit 810 that extends in the longitudinal direction and that sucks in dust through the slit 810. As shown in Figures 2 and 3, the nozzle 81 is disposed along the width direction (Y direction) of the stage 6, and is slightly longer than the width (length in the Y direction) of the stage 6, and the slit 810 is also slightly longer than the width of the stage 6. The width of the slit 810 (length in the X direction, indicated by w in Figure 1) is approximately 0.5 mm to 3.0 mm.
The nozzle 81 is installed with the slit 810 facing downward. The nozzle 81 is preferably lightweight, and from this point of view, it is made of a resin such as PVC (polyvinyl chloride) resin or PMMA (acrylic) resin. It may also be made of a metal such as aluminum.

The nozzle 81 is connected to the suction source 82 by a suction hose 821. A valve 822 is provided midway along the suction path, and is opened and closed by a signal from the main controller 7. Air is released from the suction source 82 as suction occurs, but the suction source 82 is installed outside the clean room or is configured to release air through a filter such as a HEPA filter, so that the sucked dust is not re-released into the clean room.

The dust collection means also includes a nozzle position adjustment mechanism 83 for positioning the nozzle 81 at an optimal position relative to the substrate W or stage 6. In this embodiment, the nozzle position adjustment mechanism 83 moves the nozzle 81 up and down to maintain a position a predetermined distance above the substrate W or stage 6. The device also has an upper frame (not shown) for mounting each component. The nozzle position adjustment mechanism 83 is fixed to the upper frame, and the nozzle 81 is suspended via the vertical position adjustment mechanism 83.

The vertical position adjustment mechanism 83 is equipped with a vertical drive source 831. As shown in Figures 2 and 3, the vertical drive source 831 is connected to both ends of the nozzle 81. A servo motor, for example, is used as the vertical drive source 831. The vertical drive source 831 includes a mechanism that converts rotation into vertical linear motion, using, for example, a ball screw, and both ends of the nozzle 81 are connected to the vertical drive source 831 via this mechanism. Therefore, by operating the vertical drive sources 831 on both sides in synchronization, the nozzle 81 can be raised and lowered. The nozzle 81 is attached while being held by the vertical drive sources 831 on both sides, which are fixed to the upper frame.

The device is equipped with a rangefinder that measures the distance from a reference height position to the substrate W or stage 6, and the nozzle position adjustment mechanism 83 controls the vertical drive source 831 in accordance with the measured distance. This will be explained using Figure 6, which is a front view schematic showing the adjustment of the nozzle position by the nozzle position adjustment mechanism.

In this embodiment, the distance from the reference height position to the substrate W or stage 6 is measured by a rangefinder 10 used for autofocusing during exposure by each exposure head 1 (hereinafter referred to as an AF rangefinder). As shown in Figures 1 and 6, the AF rangefinder 10 is provided in a position close to the irradiation area. In this embodiment, the stage 6 on which the substrate W is placed passes through the irradiation area once, and then exposure is performed on its way back (on the return trip). For this reason, the AF rangefinder 10 is attached to a position on the opposite side of the irradiation area from the standby position. A laser displacement meter, for example, is used as the AF rangefinder 10.

The AF rangefinder 10 is connected to the main controller 7 and sends the measured value to the main controller 7. The main controller 7 feeds this value back to the projection optical system 4 in each exposure head 1 and uses it to control the focus of the projection lenses 41, 42. In addition, the main controller 7 sends the measurement value to the nozzle position adjustment mechanism 83, which positions the nozzle 81 at the optimum vertical position in relation to the measured position of the substrate W or stage 6. That is, the height position of the nozzle 81 is calculated based on the measurement value so that the distance between the top surface of the substrate W or the top surface of the stage 6 and the bottom surface of the nozzle 81 is a predetermined distance d, and each vertical drive source 831 is controlled to position the nozzle 81 at that position.

Figure 6 shows, as an example, a state in which dust suction is performed to remove dust from the surface of the stage 6 when no substrate W is present. As shown in Figure 6, the nozzle position adjustment mechanism 83 synchronizes the vertical drive sources 831 on both sides and controls (servo controls) the distance between the top surface of the stage 6 and the bottom end of the nozzle 81 to a predetermined distance d according to the measurement value of the AF rangefinder 10.

The specified distance d is preferably approximately 0.5 mm to 3.0 mm. A smaller specified distance d is preferable because it allows dust to be sucked in with a weaker suction force, but if it is shorter than 0.5 mm, depending on the precision of the stage movement mechanism 61, etc., there is a possibility that the nozzle 81 may collide with the stage 6, which could damage the nozzle 81 or cause fragments to become a source of dust. If it is longer than 3.0 mm, a greater suction force will be required to sufficiently suck in the dust, which could result in a larger structure and the possibility of unnecessary stirring up of surrounding dust. For this reason, it is preferable that the specified distance d be 0.5 mm to 3.0 mm.

The same applies when dust collection is performed with the substrate W placed on the stage 6, but the nozzle position adjustment mechanism 83 controls the vertical drive source 831 so that a predetermined distance d is maintained based on the highest position of the heights of each part of the substrate W measured by the AF rangefinder 10. That is, there may be structures built into the substrate W due to processing that has already been performed, resulting in unevenness, and in such cases the predetermined distance d is controlled using the value of the rangefinder when the highest part is measured.
When dust is vacuumed with the substrate W placed on the stage 6, it is preferable that the negative pressure in the slit 810 of the nozzle 81 generated by the suction source 82 does not become lower than the negative pressure for vacuum suction of the substrate W on the stage 6. This is because if the pressure becomes lower than the negative pressure for vacuum suction, the substrate W may become misaligned during dust vacuuming.

The main sequence program 72 implemented in the main controller 7 includes a module that controls the operation of the dust collection means. In this embodiment, the main sequence program 72 is a sequence that operates the dust collection means after a predetermined number of exposure processes have been performed (a predetermined number of times).

The operation of the direct imaging exposure apparatus according to the embodiment having the above configuration will be described below with reference to Fig. 7. Fig. 7 is a schematic front view showing the dust collection operation in the apparatus according to the first embodiment.
When exposure is performed by the direct imaging exposure apparatus of the embodiment, the substrate W is placed on the stage 6 at a standby position by a transfer mechanism (not shown) and vacuum-adsorbed. The stage 6 on which the substrate W is placed is moved by a stage moving mechanism 61 and heads toward the irradiation area. At this time, a camera (not shown) photographs the alignment marks on the substrate W and sends the image to the main controller 7. After passing through the irradiation area once, the stage 6 turns around and heads toward the irradiation area. At this time, the AF rangefinder 10 measures the distance to the substrate W on the stage 6, and the measurement data is sent to the main controller 7.

When the substrate W on the stage 6 passes through the irradiation area on the return path, the main controller 7 executes the pixel sequence program 73 so that the irradiation area is irradiated with light of an exposure pattern by each exposure head 1. At this time, photographing data of the alignment mark taken by the camera is passed, and light of the exposure pattern is irradiated at a predetermined position, and in addition, measurement data from the AF rangefinder 10 is used to control each projection lens 41, 42, so that exposure is performed in an optimally focused state.
After exposure on the return path, the stage 6 is returned to the standby position, and a transfer mechanism (not shown) carries the substrate W out of the stage 6. Then, an unexposed substrate W is placed on the stage 6 again, and the same process is repeated.

After exposure processing has been performed on a predetermined number of substrates W in this manner, the main sequence program 72 executes a dust collection sequence. That is, the stage 6 is moved by the stage movement mechanism 61 without a substrate W placed on it, and passes through the irradiation area. The AF rangefinder 10 then measures the distance to the top surface of the stage 6 and sends this measurement data to the main controller 7. The main controller 7 then sends this measurement data to the nozzle position adjustment mechanism 63 to control the vertical drive source 831 so that the bottom end of the nozzle 81 is at a height of a predetermined distance d above the top surface of the stage 6. The suction source 82 is operated in advance, but the valve 822 is kept closed.

Then, just before the front end of the stage 6 traveling on its return path reaches a position directly below the nozzle 81, the main controller 7 opens the valve 822, causing the suction pressure (negative pressure) from the suction source 82 to act on the nozzle 81. In this state, the stage 6 passes a position directly below the nozzle 81, and at this time, dust present on the stage 6 is sucked into the nozzle 81 and removed. More specifically, as shown in FIG. 7 , in addition to dust on flat areas of the top surface of the stage 6, dust P inside the groove 601 and dust P that has entered the vacuum suction holes 602 is sucked into the nozzle 81 and removed.

When the trailing end of the stage 6 in the traveling direction passes the position directly below the nozzle 81, the main controller 7 closes the valve 822 to stop suction. Thereafter, as described above, the substrate W is placed on the stage 6, and the single wafer processing is repeated.
When removing dust adhering to the substrate W, the dust suction means is operated in the same manner with the substrate W placed on the stage 6. In this case, after passing the irradiation area and measuring the distance with the AF rangefinder 10, the stage 6 turns around, and on the return trip, the stage 6 passes the irradiation area without performing exposure and moves toward the standby position, where dust suction is performed directly below the nozzle 81. The stage 6 then turns around again and heads toward the irradiation area, and exposure is performed on the outward or return trip. This results in two round trips.

In the direct imaging exposure apparatus according to the embodiment of the present invention, dust is sucked and removed by the dust suction means, thereby avoiding the problem of exposure quality degradation due to dust. In this case, the nozzle 81 can also remove dust that has gotten into the grooves 601 and holes 602 of the stage 6, so dust that could not be removed by an adhesive roller can be sufficiently removed. This effectively improves exposure quality. The same applies to dust removal from the substrate W, where dust adhering to the step between the substrate W and the stage 6 and dust that has gotten into recesses and through-holes in the substrate W can be sufficiently removed, preventing this dust from being accidentally released and degrading exposure quality.
The "predetermined number of times" which is the interval between stage cleanings may be 1. In other words, stage cleaning may be performed every time one substrate W is processed.

Furthermore, since the nozzle position adjustment mechanism 63 is provided, the nozzle 61 can be positioned at an optimum position relative to the stage 6 or the substrate W, and an optimum suction force can be applied to the stage 6 or the substrate W. This allows for optimum dust collection.
In this case, the AF range finder 10 is also used to measure the vertical position of the stage 6 or substrate W relative to the reference height, so the structure is simplified and the number of parts is reduced, resulting in cost reduction.

In the device of the first embodiment described above, the vertical drive sources 831 that move the nozzles 81 up and down may operate synchronously or independently. In this case, a suitable control example is to control the nozzles 81 to an appropriately oblique position. This point will be explained with reference to Figure 8. Figure 8 is a schematic side view showing an example of independent control of two vertical drive sources 831.

As shown in Figure 8, by independently controlling the two vertical drive sources 831 and slightly shifting the height position of one end of the nozzle 81 from the other, the nozzle 81 assumes a slightly tilted position. In this way, if the stage 6 or substrate W assumes a slightly tilted position, the nozzle 81 can be tilted accordingly, thereby reducing the distance between the nozzle 81 and the stage 6 or substrate W in the longitudinal direction of the nozzle 81 to a predetermined distance d, with less variation. This reduces variation in the dust suction action and enables more reliable dust removal.

As shown in Figure 3, multiple AF rangefinders 10 are provided lined up in the Y direction. This makes it possible to measure variations in the height position of the stage 6 or the height position of the substrate W in the Y direction, and this variation indicates that the stage 6 or substrate W is in an oblique position. Therefore, by identifying the oblique position using the measurement data from each AF rangefinder 10 and independently controlling the two up/down drive sources 831 accordingly, dust collection can be performed more reliably.

The stage 6 is processed and manufactured with good flatness and is moved by a stage moving mechanism 61 with good linearity, so the situation shown in Figure 8 is rare, but the substrate W may be slightly warped or distorted. Even if the substrate is slightly warped or distorted, it may not be considered a defective product, and dust collection may be performed in the state shown in Figure 8. Therefore, it is advantageous to be able to control the two vertical drive sources 831 to position the nozzle 81 at an appropriate angle.
The control to maintain the oblique posture is set within the range of allowable gaps in the connection structure of the two vertical drive sources 831 to the nozzle 81. Alternatively, an elastic hinge or the like may be appropriately provided in the connection structure to the nozzle 81 so that the oblique posture can be maintained and the nozzle 81 can be driven up and down.

In addition to electric actuators such as servo motors, fluid pressure actuators such as air cylinders may also be used as the vertical drive source 831. When using a fluid pressure actuator, the vertical position can be adjusted by appropriately positioning stoppers. The nozzle 81 can be controlled to assume an oblique position by positioning the left and right stoppers at different heights.

Furthermore, it is not necessary to provide the vertical drive sources 831 at both ends of the nozzle 81; a single vertical drive source can be provided in the center of the length (Y direction) to move it up and down. In this case, the vertical drive source can be electric or hydraulic. When providing a drive source in the center to move it up and down, linear guides are provided at both ends, but if the nozzle 81 is not particularly long, linear guides can be omitted and the accuracy of the vertical position can be ensured by the linearity of the vertical drive source. Alternatively, a single linear guide can be provided in the center, and products that combine an air cylinder with a linear guide provided behind it as a unit are commercially available, so this can also be used.

Next, a direct imaging exposure apparatus according to a second embodiment will be described. Figures 9 and 10 are schematic diagrams of the main parts of the direct imaging exposure apparatus according to the second embodiment, with Figure 9 being a schematic front view and Figure 10 being a schematic side view.
As shown in Figures 9 and 10, the direct imaging exposure device of the second embodiment is also provided with a dust collection means, which includes a nozzle 81 and a suction source 82 connected to the nozzle 81 via a suction hose 821.

In the second embodiment, in order to enhance the dust suction effect of the dust suction means, a brush 84 is employed. As shown in Figures 9 and 10, the nozzle 81 is a hollow member, and the brush 84 is disposed inside the nozzle 81.
In this embodiment as well, the nozzle 81 is long in the width direction (Y direction) of the stage 6. A band-shaped holder 841 extending in the same direction as the nozzle 81 is fixed inside the nozzle 81, and the brush 84 is attached to the underside of the holder 841.

As shown in Figures 9 and 10, the brush 84 has a length that allows it to pass through the suction port 810 of the nozzle 81 and slightly protrude from the suction port. In other words, the brush 84 is covered by the nozzle 81 except for its tip. Each wire of the brush 84 has appropriate elasticity, and the protruding length of the brush 84 in its free state (shown as L in Figure 9) is slightly longer than the aforementioned predetermined distance d. Therefore, when the nozzle 81 is positioned so as to maintain the predetermined distance d from the stage 6 or substrate W, each wire of the nozzle 81 is slightly bent. The protruding length L is, for example, approximately 1 mm to 3 mm longer than the predetermined distance d.

Such brush 84 is preferably a so-called anti-static brush. That is, it is preferable that each wire of the brush 84 is conductive and attached in a grounded state. For example, the holder can be made of metal, and the brush 84 can be grounded via the holder as shown in Figure 9. The anti-static brush 84 can be made of amorphous metal fiber, stainless steel fiber, carbon fiber, Thunderon, or other suitable material.

The operation of the dust suction means provided with the brush 84 will be described with reference to Fig. 11. Fig. 11 is a schematic front view showing the operation of the dust suction means in the second embodiment. Fig. 11 shows dust suction for the stage 6 as an example.
In the second embodiment, too, the brush 84 is positioned above the stage 6 at a predetermined distance d with respect to the stage 6 when, for example, there is no substrate W present, and the stage 6 is moved in this state by the stage moving mechanism 61. At this time, as shown in Figure 11, each wire of the brush 84 has a protruding length L in its free state that is longer than the predetermined distance d, and therefore, due to its elasticity, it enters the grooves 601 and holes 602 of the stage 6 and efficiently scrapes out the dust P adhering to the inside of the grooves 601 and holes 602. The scraped-out dust P is sucked through the slits 810, enters the nozzle 81, and is discharged through the suction hose 821.

As described above, according to the second embodiment, dust P in the grooves 601 and holes 602, which could not be removed by conventional dust removal using an adhesive roller, is scraped out by the brush 84 and efficiently removed. This further improves the exposure quality. The same applies to dust adhering to step portions of the substrate W.
In the second embodiment, the brush 84 is a static elimination brush, which eliminates static electricity from the stage 6 and dust. This allows dust electrostatically adsorbed to the stage 6 to be sufficiently removed. The same is true for dust P adhering to the grooves 601 and holes 602; static elimination makes it easier to scrape out the dust P, allowing for more efficient dust collection, further enhancing the above-mentioned effect.

The brush 84 protrudes from the slit 811 of the nozzle 81 and is covered by the nozzle 81 except for its tip, which is significant in that it can reliably remove dust scraped out by the brush 84 without scattering it. A similar structure could be adopted in which the brush 84 is positioned in front of the nozzle 81. "In front" means the position that first faces the stage 6 or the substrate W when the stage 6 or the substrate W moves. Even with this structure, dust can be removed from the grooves 601 and holes 602, but if the brush 84 scatters the dust outside the area that can be sucked by the nozzle 81 when scraping out the dust, it will not be able to be sucked up. With the structure in which the brush 84 extends through the slit 811 of the nozzle 81 as described above, this problem does not occur, and the dust is reliably sucked up and removed.
As another structure, it is conceivable to fix the brush 84 to the lower surface (the surface where the slit 811 is provided) of the nozzle 81. Although this structure is also acceptable, a structure in which the brush 84 is disposed through the suction port is more effective.

Next, a direct imaging exposure apparatus according to a third embodiment will be described. Figures 12 and 13 are schematic diagrams showing the main components of the direct imaging exposure apparatus according to the third embodiment, with Figure 12 being a schematic front view and Figure 13 being a schematic side view.
The third embodiment also includes a dust suction means, which includes a nozzle 81 and a suction source 82 connected to the nozzle 81 via a suction hose 821. In the third embodiment, the nozzle 81 includes wheels 85, as shown in Figures 12 and 13 .

As shown in Figures 12(1) and 13, two wheels 85 are provided on both ends of the nozzle 81 in the Y direction. However, as shown in Figure 12(2), there are also cases where wheels 85 are provided on both ends in the X direction, making a total of four. Although not shown, each wheel 85 is fitted with a tire made of a material that suppresses dust generation.
These wheels 85 are employed as a simple structure for maintaining the aforementioned predetermined distance d. That is, the axle of each wheel 85 is fixed within the nozzle 81, and the fixed position is such that the protruding length of the wheel 85 from the underside of the nozzle 81 coincides with the predetermined distance d. Therefore, as shown in FIGS. 12 and 13 , when each wheel 85 is in contact with the stage 6, the nozzle 81 maintains the predetermined distance d from the stage 6. When the stage 6 moves, the distance d is maintained and each wheel 85 rolls (following rotation). This provides a sufficient suction effect on dust adhering to the stage 6. In this case, because the predetermined distance d is maintained by each wheel 85, there is no need for feedback control of the position of the nozzle 81, which is convenient.

The structure of the third embodiment may also be applied to dust removal from the substrate W, but there are cases where it is not preferable to have the wheels 85 contact the substrate W. In such cases, a structure can be adopted in which each wheel 85 contacts the stage 6 outside the substrate W. In this case, the protruding length of each wheel 85 is set to a length obtained by adding the thickness of the substrate W to the predetermined distance d.
In the third embodiment, the brush 84 can be used in combination with the nozzle 81 as in the second embodiment, and it is preferable that the brush 84 be arranged inside the nozzle 81 and project through the suction port.

In each of the above-described embodiments, the nozzle 81 was positioned between the standby position and the irradiation area, but it may also be located on the opposite side of the irradiation area from the standby position. In this case, the stage 6 or substrate W passes through the irradiation area once, and then dust is vacuumed on the opposite side. With this configuration, even when vacuuming dust on the substrate W, exposure can be performed as it passes through the irradiation area on the return trip, so there is no need to make two round trips.

Including the above variants, it is preferable not to perform dust vacuuming while exposure is taking place; that is, it is preferable to avoid simultaneous exposure and dust vacuuming. This is because vibrations may occur during dust vacuuming, and even slight vibrations may affect exposure. For example, when vacuuming a substrate W in a configuration in which the nozzle 81 is positioned close to the irradiation area, the nozzle 81 scans the substrate W as the stage 6 moves, and it is possible that the front portion of the substrate W in the direction of movement will finish vacuuming and reach the irradiation area. In this case, exposure will be performed on the front portion while vacuuming is being performed on the rear portion. This configuration is not preferable as it may be affected by vibrations. To avoid this, the nozzle 81 can be positioned away from the irradiation area, and the front end of the substrate W can enter the irradiation area and expose after vacuuming has been completed up to the rear end.

In each of the above embodiments, the AF rangefinder 10 is also used as the rangefinder for exposure, but a rangefinder separate from the AF rangefinder 10 may also be provided. For example, a rangefinder may be provided immediately after the standby position, where it measures the distance, and the nozzle 81 scans the stage 6 or substrate W just before the irradiation area to perform dust collection.

Furthermore, a rangefinder is not essential for practicing the present invention, and in some cases a rangefinder may not be necessary. For example, when only vacuuming the stage 6, if the height position of the upper surface of the stage 6, which is moved by the stage movement mechanism 61, is always constant and stable, it is sufficient to position the nozzle 81 at a predetermined distance d from that position, and no rangefinder is required. When vacuuming the substrate W, if there are no major changes in the thickness of the substrate W, or if there is a change but the degree of change does not affect the vacuuming action, it is sufficient to position the nozzle 81 at a certain height position, and no rangefinder is required. Furthermore, in these cases, it may not be necessary to adjust the position of the nozzle 81, and it may be possible that the nozzle position adjustment mechanism 83 is not provided (if the nozzle 81 is fixedly provided).

The suction source 82 can be a blower such as a ring blower, or a vacuum pump. In this case, it is also possible to use a vacuum pump to exhaust the vacuum suction holes in the stage 6.

In each of the above-described embodiments, the direct imaging exposure apparatus may have a so-called twin-stage configuration. A twin-stage configuration is one in which two stages are provided, with standby positions for the stages on either side of an irradiation area. The two stages alternately move back and forth through the irradiation area, and the substrates W placed on each stage are alternately exposed. In this case, the dust collection means may be shared to collect dust from both stages and the substrates W on both stages, or may be provided separately to collect dust from each stage and the substrates on each stage.

REFERENCE SIGNS LIST 1 exposure head 10 AF rangefinder 6 stage 601 groove 602 vacuum suction hole 61 stage movement mechanism 7 main controller 72 main sequence program 81 nozzle 82 suction source 821 suction hose 822 valve 83 nozzle position adjustment mechanism 831 up and down drive source 84 brush 85 wheel W substrate P dust

Claims (8)

A direct imaging exposure apparatus that forms an exposure pattern using a spatial light modulator and exposes a substrate,
an exposure head including a light source and a spatial light modulator;
a stage on which a substrate is placed;
a stage moving mechanism that moves the stage so that the substrate passes through an irradiation area, which is an area onto which light of an exposure pattern is irradiated by the exposure head;
a dust suction means for removing dust adhering to the stage or the substrate placed on the stage by suction using negative pressure;
The dust suction means includes a nozzle and a suction source connected to the nozzle,
A brush made of elastic wire is provided,
When the stage is moved by the stage moving mechanism, the brush comes into contact with the stage or the substrate on the stage, causing the wire to bend;
The nozzle is positioned so that it can suck up dust scraped off by the brush wires while the stage is being moved by the stage moving mechanism,
The nozzle has a long slit,
the nozzle is positioned a predetermined distance above the stage or the substrate placed on the stage;
The nozzle is provided so that the length direction of the slit is horizontal and perpendicular to the direction of movement of the stage .
the nozzle has a shape that covers the brush except for the tip of the wire,
A direct imaging exposure apparatus characterized in that the length of the wire projecting from the nozzle is 1.5 mm or more and 6 mm or less . A direct imaging exposure apparatus as described in claim 1, characterized in that the nozzle is provided with a nozzle position adjustment mechanism that adjusts the distance from the stage or the substrate placed on the stage to the predetermined distance. a rangefinder is provided to measure the distance of the stage or the substrate relative to a reference height;
3. A direct imaging exposure apparatus according to claim 2, wherein said nozzle position adjusting mechanism includes a vertical drive source for adjusting the position of said nozzle by moving said nozzle vertically in accordance with data measured by a range finder. the exposure head includes a projection lens that projects the formed exposure pattern onto an irradiation area;
an autofocus rangefinder is provided to measure the distance to the surface of the substrate in order to focus the projection of the exposure pattern by the projection lens;
4. A direct imaging exposure apparatus according to claim 3, wherein the rangefinder also serves as a rangefinder for autofocus. A direct imaging exposure apparatus as described in any one of claims 1 to 4, characterized in that the brush is capable of entering a groove or hole in the stage with the wire bent when the stage is moved by the stage movement mechanism, or capable of abutting against a step between the stage and the substrate. 6. A direct imaging exposure apparatus according to claim 1, wherein the nozzle is conductive and grounded. a control unit for controlling the stage moving mechanism and the dust suction means;
The control unit is equipped with a main sequence program.
7. The direct imaging exposure apparatus according to claim 1, wherein the main sequence program is programmed to perform a predetermined number of exposure processes in which a substrate is placed on the stage and the stage is moved by the stage movement mechanism, and then to perform stage cleaning in which dust is sucked and removed by positioning the nozzle a predetermined distance above the stage with no substrate placed on the stage and moving the stage by the stage movement mechanism. A method for cleaning a stage in a direct imaging exposure apparatus that includes an exposure head including a light source and a spatial light modulator, a stage on which a substrate is placed, and a stage movement mechanism that moves the stage so that the substrate passes through an irradiation area that is an area that is irradiated with light of an exposure pattern by the exposure head, and that forms an exposure pattern by the spatial light modulator to expose the substrate, comprising:
A stage cleaning method for a direct imaging exposure apparatus, characterized in that a nozzle (excluding a nozzle attached to a member that adsorbs and fixes a substrate for carrying in the substrate) that has a long slit in the horizontal direction perpendicular to the direction of movement of the stage by the stage movement mechanism and that is connected to a suction source is positioned a predetermined distance above the stage with no substrate placed on it, and the stage is moved in this state by the stage movement mechanism, thereby sucking and removing dust that has adhered to the stage.