JP7196011B2 - Direct exposure system - Google Patents

Description

The invention of this application relates to a direct drawing exposure apparatus that irradiates and exposes a work with light of a predetermined pattern without using a mask. A predetermined pattern of light in exposure is hereinafter referred to as an exposure pattern.

2. Description of the Related Art An exposure technique for exposing an object having a photosensitive layer formed on its surface to expose the photosensitive layer is widely used as a main technique of photolithography for forming various fine circuits and fine structures. A typical exposure technique is to irradiate light onto a mask on which a pattern similar to the exposure pattern is formed, and project the image of the mask onto the surface of the object so that the object is irradiated with the light of the exposure pattern. It is a technology to

Apart from exposure techniques using such masks, techniques are known in which spatial light modulators are used to directly image and expose the surface of an object. This technique is hereinafter referred to as direct writing exposure in this specification.
In direct writing exposure, a typical spatial light modulator is a DMD (Digital Mirror Device). A DMD has a structure in which minute rectangular mirrors are arranged in a rectangular lattice. The angle of each mirror with respect to the optical axis is independently controlled, and it can take an attitude that reflects the light from the light source and reaches the target, and an attitude that prevents the light from the light source from reaching the target. It is designed to be obtained. The DMD has a controller that controls each mirror, and the controller controls each mirror according to the exposure pattern so that the surface of the object is irradiated with the light of the exposure pattern.

Since the direct writing exposure does not use a mask, it is superior in high-mix low-volume production. In the case of exposure using a mask, it is necessary to prepare a mask for each type, which incurs a large cost including the cost of storing the mask. In addition, when exchanging masks for production of different types, it is necessary to stop the operation of the apparatus, and it takes time and effort to restart. For this reason, it becomes a factor of lowering productivity. On the other hand, in the case of direct writing exposure, it is sufficient to prepare a control program for each mirror for each type of product. The superiority of In addition, it is possible to finely adjust the exposure pattern for each work (object to be exposed) as necessary, and the flexibility of the process is excellent.

In such a direct writing exposure apparatus, a stage on which a work is placed is used in order to make the work perpendicular to the optical axis of an exposure unit containing a spatial light modulator. The exposure unit irradiates a set area (hereinafter referred to as an exposure area) with light of an exposure pattern. The workpiece is exposed as it passes through.

Such a direct writing exposure apparatus often employs a twin-stage configuration in which two stages are mounted in order to improve productivity. The configuration disclosed in Patent Document 1 is also an example. In the twin-stage configuration, stages are arranged on both sides of an exposure area, and exposure is performed by alternately passing the stages on which workpieces are placed through the exposure area. In this case, a loading/unloading mechanism is installed on one side of the exposure area, and a loading/unloading mechanism is installed on the other side.

Japanese Unexamined Patent Application Publication No. 2008-191303

In the direct writing exposure apparatus described above, it is often required to expose both sides of the workpiece. In the case of exposing both sides, two direct writing type exposure devices are installed vertically, one side is exposed by the first side, and the other side is exposed by the second side. A reversing mechanism for turning over the work is installed between the first device and the second device.
When two direct writing exposure apparatuses are vertically arranged in this way, the configuration of the twin stages is also changed. One side of the exposure area is dedicated to loading and the other side is dedicated to unloading. The unloading mechanism on the other side transfers the exposed workpiece to the reversing mechanism, which inverts it and then transfers it to the loading mechanism of the second direct drawing exposure apparatus.

The two stages alternately move to the load position because the workpiece is placed only on one side. The stage on which the workpiece is placed at the load position passes through the exposure area for exposure and moves to the other side. done. The two stages are cantilevered so as not to interfere with each other. That is, one stage is held by an arm extending from, for example, the left side with respect to the transport direction, and the other stage is held by an arm extending from the right side. An elevating mechanism is connected to each of the arms, and when one of the stages is moving along the transfer line, it is configured to retreat upward or downward so as not to interfere.

As described above, the twin-stage direct writing exposure apparatus equipped with two stages greatly improves productivity compared to the apparatus equipped with only one stage. However, it tends to be structurally complicated, large-scale, and expensive. This problem is noticeable in configurations where one side is dedicated to loading and the other side is dedicated to unloading.
In addition, since the other stage cannot advance on the transfer line until the evacuation operation of one stage is completed, the tact time may be limited by this portion. If this happens, the superiority of the twin stage will be hindered, and productivity will not improve greatly.

The invention of this application was made in order to solve such problems in productivity of the direct-writing exposure apparatus, and has a simple structure, which can reduce the cost and execute the exposure process with high productivity. It is an object of the present invention to provide a direct drawing exposure apparatus capable of

In order to solve the above problems, the direct writing exposure apparatus of this application is a direct writing exposure apparatus that irradiates and exposes a plate-like or sheet-like work with light of a predetermined pattern without a mask, It has an exposure head that irradiates a predetermined pattern of light onto a set exposure area, and a transport system that transports a workpiece through the exposure area. The work transport system includes a circulating mechanism that circulates along an endless circuit a work mount that is in a flat posture perpendicular to the optical axis of the exposure head when passing through the exposure area, and a work mount. A loader for placing an unexposed work on a part and an unloader for recovering an exposed work from the work placing part.
Further, in order to solve the above-mentioned problems, the direct writing exposure apparatus has an alignment at a position where the state of the workpiece is detected on the peripheral circuit between the exposure area and the placement work position where the loader places the unexposed workpiece. and an alignment means for correcting the irradiation position of the predetermined pattern of light from the exposure head based on the signal from the alignment sensor.
Further, in order to solve the above problem, the alignment means may be means for correcting the irradiation position based on a signal from an alignment sensor that detects the state of the work moving on the circuit.
In order to solve the above problems, the direct writing exposure apparatus includes a projection optical system in which an exposure head forms an exposure pattern, and a loader includes a placement work position where an unexposed work is placed and an exposure area. An auto focus sensor that measures the distance to the work placed on the work placement part is provided on the circuit between the It can have a configuration in which a focusing means is provided.
Further, in order to solve the above problem, the autofocus means may be means for controlling the projection optical system in accordance with a signal from an autofocus sensor that measures the distance to the work moving on the circuit.
Further, in order to solve the above-described problem, the direct drawing exposure apparatus can include a suction mechanism that sucks the work placed on the work placement section to the work placement section at least when the work passes through the exposure area.
In order to solve the above-described problems, the direct drawing exposure apparatus includes a suction mechanism that sucks the workpiece, whose state is detected by the alignment sensor, to the workpiece placement section at least from the point of detection until the workpiece passes through the exposure area. be prepared.

As will be described below, according to the direct drawing exposure apparatus of this application, when the stage revolving along the endless circuit is positioned at the mounting work position, the work is placed on the stage. Exposure is performed when the stage passes through the exposure area, and the work is recovered from the stage when it reaches the recovery work position. can be reduced. Also, the tact time is determined by the exposure in the exposure unit, and is not determined by the transport operation of the workpiece. Therefore, a practical apparatus is provided that can perform the exposure process with high productivity.
Further, if the state of the work is detected on the circuit between the placement work position and the exposure area and the irradiation position of the exposure pattern is corrected accordingly, the work may be displaced on the work placement section. The correct position is irradiated with the light of the exposure pattern. Therefore, exposure with higher positional accuracy can be performed.
Further, if the alignment means is means for correcting the irradiation position of the exposure pattern based on a signal from an alignment sensor that detects the state of the work moving on the circular circuit, the operation of the revolving mechanism for detecting the state of the work is performed. There is no need to stop the exposure unit, and the control of the exposure unit does not become complicated.
In addition, in a configuration in which an autofocus sensor measures the distance to the work on the circuit between the placement work position and the exposure area and the result is used for autofocus control of the projection optical system, a clearer image of the work can be obtained. Since the exposure pattern is irradiated, exposure with higher accuracy can be performed. At this time, in the configuration in which the autofocus sensor measures the distance to the work moving on the circuit, there is no need to stop the operation of the circuit mechanism to measure the distance, and the control of the exposure unit does not become complicated.
In addition, in the configuration in which the work placed on the work placement part is attracted to the work placement part at least when passing through the exposure area, even if the work has deformation such as warping, the deformation is eliminated. is exposed. Therefore, exposure processing can be performed with higher accuracy.
In addition, in a configuration in which the workpiece is adsorbed to the workpiece placement unit from the time the alignment sensor detects the state until it passes through the exposure area, the position shifts during transportation, which reduces the accuracy of the irradiation position of the exposure pattern. You won't end up doing it. Therefore, in this respect, exposure processing can be performed with higher accuracy.

1 is a schematic front view of a direct drawing exposure apparatus according to an embodiment; FIG. 1 is a schematic plan view of a direct drawing exposure apparatus according to an embodiment; FIG. 3 is a schematic diagram of an exposure unit in the direct drawing exposure apparatus of the embodiment; FIG. It is the perspective schematic diagram shown about an exposure area. FIG. 3 is a schematic perspective view of a circulation mechanism included in the transport system; It is the perspective schematic diagram shown about the connection structure of each stage. FIG. 4 is a schematic side cross-sectional view showing adsorption of a workpiece by an adsorption mechanism;

Next, a mode (hereinafter referred to as an embodiment) for carrying out the invention of this application will be described.
1 and 2 are schematic views of a direct drawing exposure apparatus according to an embodiment, FIG. 1 being a schematic front view and FIG. 2 being a schematic plan view. The direct writing exposure apparatus shown in FIGS. 1 and 2 includes an exposure unit 1 that irradiates an exposure area with light of an exposure pattern, and a transport system 2 that transports a work W through the exposure area.
The workpiece W has a plate shape in this embodiment. More specifically, in this embodiment, the direct writing exposure apparatus is an apparatus for manufacturing printed circuit boards, and therefore the work W is a substrate for printed circuit boards. As for the printed circuit board, a sheet-like soft circuit board is also known, but in this embodiment, the printed circuit board is a rigid circuit board made of a resin such as polyimide.

FIG. 3 is a schematic diagram of the exposure unit 1 in the direct drawing exposure apparatus of the embodiment. As shown in FIG. 3, the exposure unit 1 includes a light source 11, a spatial light modulator 12 that spatially modulates the light from the light source 11, and an image formed by the light modulated by the spatial light modulator 12 in an exposure area. and an optical system for projection (hereinafter referred to as a projection optical system) 13 .

As the light source 11, one that outputs light of an optimum wavelength according to the photosensitive wavelength of the photosensitive layer on the work W is used. In many cases, the photosensitive wavelength of the resist film ranges from the visible short wavelength region to the ultraviolet region, and the light source 11 that outputs light from the visible short wavelength region to the ultraviolet region such as 405 nm or 365 nm is used. In order to make the best use of the performance of the spatial light modulator 12, it is preferable to output coherent light, so a laser light source is preferably used. For example, a gallium nitride (GaN) based semiconductor laser is used.

A DMD is used as the spatial light modulator 12 in this embodiment. As described above, in DMD, each pixel is a minute mirror (not shown in FIG. 2). A mirror (hereinafter referred to as a pixel mirror) is, for example, a square mirror of about 13.68 μm square, and has a structure in which a large number of pixel mirrors are arranged in a rectangular lattice. The number of arrays is, for example, 1024×768.

The spatial light modulator 12 has a modulator controller 121 that controls each pixel mirror. The direct drawing exposure apparatus of the embodiment includes a main control section 9 that controls the whole. A modulator controller 121 controls each pixel mirror according to a signal from the main controller 9 . The plane on which the pixel mirrors are arranged is used as a reference plane for each pixel mirror. It is designed to be able to take a posture. In this embodiment, the first orientation is the off state and the second orientation is the on state.
The spatial light modulator 12 includes a drive mechanism that drives each pixel mirror, and the modulator controller 121 independently controls whether each pixel mirror is in the first or second orientation. It is possible. Such spatial light modulators 12 are available from Texas Instruments.

As shown in FIG. 3, the exposure unit 1 includes an irradiation optical system 14 that irradiates the spatial light modulator 12 with light from the light source 11 . In this embodiment, illumination optics 14 includes optical fiber 141 . In order to form an image with higher illuminance, one exposure unit 1 is equipped with a plurality of light sources 11 and an optical fiber 141 is provided for each light source 11 . As the optical fiber 141, for example, a silica-based multimode fiber is used.

In order to form an image with high accuracy using the spatial light modulator 12, which is a DMD, it is desirable to make parallel light incident and reflected by each pixel mirror, and to obliquely direct the light to each pixel mirror. It is desirable to make it incident. For this reason, as shown in FIG. 3, the irradiation optical system 14 includes a collimator lens 142 for collimating the light emitted from each optical fiber 61 and spreading, and a collimator lens 142 for causing the light to enter the spatial light modulator 12 obliquely. and a reflecting mirror 143 . “Obliquely” means obliquely with respect to the reference plane of the spatial light modulator 12 . In terms of the angle of incidence with respect to the reference plane, the angle is, for example, about 22 to 26°.

The projection optical system 13 is composed of two projection lens groups 131 and 132, a microlens array (hereinafter abbreviated as MLA) 133 arranged between the projection lens groups 131 and 132, and the like. The MLA 133 is arranged in an auxiliary manner in order to perform exposure with higher shape accuracy. The MLA 133 is an optical component in which a large number of minute lenses are arranged in a rectangular lattice. Each lens element corresponds to each pixel mirror of the spatial light modulator 12 on a one-to-one basis.

In the exposure unit 1 described above, the light from the light source 11 is guided through the optical fiber 141 and then enters the spatial light modulator 12 through the irradiation optical system 14 . At this time, each pixel mirror of the spatial light modulator 12 is controlled by the modulator controller 121 to be selectively tilted according to the exposure pattern to be formed. That is, according to the exposure pattern to be formed, the pixel mirrors located at the positions where the light should reach the exposure area are in the second posture (on state), and the other pixel mirrors are in the first posture (off state). state). Light reflected by off-state pixel mirrors does not reach the exposure area, and only light reflected by on-state pixel mirrors reaches the exposure area. Therefore, the exposure area is irradiated with light of a predetermined exposure pattern.

A control signal is sent from the main controller 9 to each modulator controller 121 so that a predetermined exposure pattern is achieved. The control signal is the sequence that drives each pixel mirror. A program 91 including each sequence to be sent to each modulator controller 121 is stored in a storage section 900 of the main control section 9 in order to achieve a predetermined exposure pattern. This program will be referred to as an exposure pattern program 91 hereinafter. The exposure pattern program 91 is created in advance based on design information indicating what kind of circuit is to be formed on the workpiece W, and is stored in the storage section 900 of the main control section 9 .

A plurality of such exposure heads 1 are provided. As shown in FIG. 2, eight exposure heads 1 are provided in this embodiment. Eight exposure heads 1 form one exposure pattern as a whole. Each exposure head 1 has the same configuration.
The exposure area is supplemented with reference to FIG. FIG. 4 is a schematic perspective view showing the exposure area. In FIG. 4, an area (hereinafter referred to as an individual area) E that can be irradiated with light by one exposure head 1 is indicated by a square frame. A collection of individual areas E is an exposure area.

The work W is irradiated with light in each individual area E while moving in the direction indicated by the arrow in FIG. 4 (conveyance direction). At this time, since the two rows of exposure heads 1 are arranged to be offset from each other, exposure can be performed without gaps even in the horizontal direction perpendicular to the conveying direction.
Actually, each individual area E is a collection of minute irradiation patterns (hereinafter referred to as minute patterns). One micropattern is a pattern by one pixel mirror 31 . The workpiece W placed on the stage 3 moves in the exposure area as the stage 3 moves, and the minute patterns are turned on and off in a predetermined sequence in accordance with the timing of the movement. Thereby, a desired exposure pattern is formed on the workpiece W. FIG.

Next, the transport system 2 will be explained.
A major feature of the direct drawing exposure apparatus of this embodiment is that it employs a revolving mechanism 21 that revolves a member (work placement unit) on which a work W is placed along an endless loop. is. Specifically, in this embodiment, the work placement section is the stage 3 . The stage 3 is a low platform-shaped member. The revolving mechanism 21, as shown in FIG. 1, is a mechanism that revolves the stage 3 in a vertical plane.

FIG. 5 is a schematic perspective view of the circulation mechanism 21 included in the transport system 2. As shown in FIG. FIG. 6 is a schematic perspective view showing the connection structure of each stage. In the following description, the traveling direction of each stage 3 is defined as the front-rear direction, and the horizontal direction perpendicular thereto is defined as the left-right direction.
As shown in FIGS. 1 and 5, a large number of stages 3 are arranged along an endless circuit. Although not shown in FIG. 5, each stage 3 is connected to each other by a connector 31 as shown in FIG. Each stage 3 has connecting portions 32 in the front and rear. Each connecting portion 32 is a portion extending forward and backward from the stage 3 . The connecting portions 32 are provided on the left and right, and a total of four connecting portions 32 are provided. The connector 31 is a connecting pin in this embodiment. Each connecting portion 32 is formed with a pin insertion hole, and each stage 3 is connected by inserting a connection pin into the pin insertion hole.
Each stage 3 has a pair of rear connecting portions 32 and a single front connecting portion 32 . Each stage 3 is connected by a connector 31 in such a state that the front connecting portion 32 is inserted between the rear connecting portions 32 of the front stage 3 .

As shown in FIG. 5 , the circulation mechanism 21 includes a pair of drive wheels 22 and a pair of driven wheels 23 . The pair of driving wheels 22 are arranged on the front side of the circuit. The pair of drive wheels 22 are fixed to a drive shaft 221 extending laterally, and a drive source (not shown) is connected to the drive shaft 221 . A pair of driven wheels 23 are arranged on the rear side of the circuit. The pair of driven wheels 23 are fixed or connected to a driven shaft 231 extending laterally.

Each stage 3 is formed with a plurality of engaging holes 34 on the lateral sides thereof. As shown in FIG. 5, each drive wheel 22 and each driven wheel 23 is gear-shaped and has meshing teeth. Each meshing hole 34 is sized and shaped to fit each meshing tooth. When the pair of driving wheels 22 are driven by a drive source (not shown) to rotate, the meshing teeth are sequentially meshed with the meshing holes 34 to move the connected stages 3 along the circuit. At this time, the meshing teeth of the driven wheel 23 are also driven while sequentially meshing with the meshing holes 34 . In this way, each stage 3 revolves along the circuit.

On the other hand, as shown in FIGS. 1 and 2 , a loader 4 is provided behind the circulation mechanism 21 and an unloader 5 is provided in front of the circulation mechanism 21 . The loader 4 is a mechanism for placing the work W on the stage 3 , and the unloader 5 is a mechanism for recovering the exposed work W from the stage 3 .

A carry-in conveyor 40 is located where the loader 4 is installed. The loader 4 includes a carry-in hand 42 having a suction pad 41 and a carry-in hand drive mechanism 43 for moving the carry-in hand 42 vertically, forward, backward, leftward, and rightward. A plurality of suction pads 41 are provided in a downward posture, and are capable of sucking and holding the work W by vacuum suction.
At the place where the unloader 5 is installed, there is a carry-out conveyor 50 for sending the work W to the next process. Like the loader 4, the unloader 5 also includes a carry-out hand 52 having a suction pad 51, and a carry-out side hand drive mechanism 53 for moving the carry-out hand 52 vertically, forward, backward, leftward, and rightward.

As can be seen from the above description, each stage 3 is rotated by the rotation mechanism 21, but the workpiece W is placed on the stage 3 only while it is moving in the upper part of the peripheral path shown in FIG. is. During this time, the work W passes through the exposure area and is exposed. Hereinafter, the upper portion of this circuit will be referred to as the main transport path. Further, the position where the loader 4 performs the operation of placing the work W is called the placement work position, and the position where the unloader 5 performs the operation of collecting the work W is called the recovery work position.

It should be noted that the rotation speed of each stage 3 by the rotation mechanism 21 is a speed determined by the exposure performed by each exposure unit 1 . That is, as described above, each exposure pattern program 91 is implemented for each exposure unit 1, but the on/off sequence of each pixel mirror here assumes that the workpiece W moves at a constant speed. and The speed is predetermined in relation to the required amount of exposure, and each exposure pattern program 91 is programmed on the premise of this. Then, a control signal is sent to the revolving mechanism 21 so that it revolves at this constant speed.

The direct drawing exposure apparatus of such an embodiment is provided with means for increasing the pattern accuracy of exposure processing. Specifically, there are provided alignment means for correcting the exposure pattern according to the state of the work W when it is transported to the exposure area, and autofocus means for controlling the projection optical system 13 to sharpen the exposure pattern. ing.
First, the alignment means will be described. The alignment means includes pre-alignment means and main alignment means. The pre-alignment means is means for adjusting the placement position of the work W for the main alignment. This alignment means is means for correcting the exposure pattern according to the state of the work W. FIG.

As shown in FIG. 1, an alignment sensor is provided on the main transport path. In this embodiment, the alignment sensor is the imaging device 61 . A plurality of alignment marks are provided on the workpiece W, and an imaging device 61 is provided at each position for imaging each alignment mark.

The pre-alignment means is a means for performing mechanical alignment in this embodiment. The purpose of the pre-alignment is to bring each alignment mark into the field of view (capturable range) of the imaging device 61 when the workpiece W is transported along the main transport path. Although not shown, the prealignment means includes a backing plate fixed at a predetermined position with a predetermined posture. The backing plate is, for example, a band plate-shaped member forming an angle of 90 degrees, and is arranged with the width direction being the vertical direction. Pre-alignment is performed using the loading hand 42 . That is, when the carrying-in hand 42 holds the work W, it is brought into contact with the backing plate, and in that state, the work W is again held in a predetermined positional relationship. Pre-alignment is thus performed.

Incidentally, as shown in FIG. 1, the imaging element 61 is positioned above the main transport path. This position is a position where the alignment mark of the work W moving on the main transport path comes into the field of view. In other words, the work W is prealigned by the prealignment means so that the alignment marks are within the field of view of the imaging device 61 when the work W is moved on the main transport path.

This alignment is an operation of judging the state of the workpiece W from the imaging element 61 and changing the exposure pattern accordingly. The “work W state” includes the position of the work W with respect to each exposure unit 1 . That is, when the workpiece W passes through the exposure area, the formation position of the exposure pattern (light irradiation position of the exposure pattern) is changed according to the position. That is, how much and in what direction the position of the work W when passing through the exposure area is deviated from the reference position is determined from the data from the imaging device 61, and the exposure pattern forming position is changed accordingly. The change of the formation position of the exposure pattern is performed in the form of changing (rewriting) the exposure pattern program 91 . The alignment means includes an exposure pattern rewrite program 62 mounted on the main controller 9 . The exposure pattern rewriting program 62 is programmed to process the data from each imaging device 61, calculate the formation position of the exposure pattern, and rewrite the exposure pattern program 91 with the result. Since the imaging device 61 captures an image of the alignment mark of the workpiece W that is moving on the main conveying path, in actuality, appropriate still image data is extracted from the moving image data, and processed by extracting the data of the workpiece W. The deviation of the position of W from the reference position is determined.

An exposure sequence program 90 is installed in the main control section 9 to operate each section of the apparatus in a predetermined sequence. The exposure pattern rewrite program 62 is called from the exposure sequence program 90 and executed each time a signal is output from each imaging device 61 .

Next, the autofocus means will be explained.
The autofocus means includes an autofocus sensor 63 and an autofocus program 64 for generating a control signal for the projection optical system 3 according to the signal from the autofocus sensor 63 . The autofocus means is means for controlling the projection optical system 13 according to the distance (distance in the optical axis direction) from the projection optical system 13 to the work W when passing through the exposure area. In this embodiment, the autofocus sensor 63 is a rangefinder arranged on the main transport path in front of the exposure area. A laser rangefinder or the like using laser interference is used as the autofocus sensor 63 . The autofocus sensor 63 is arranged above the main transport path and measures the distance to the work W at a position slightly before reaching the exposure area.

The main control unit 9 has an automatic control unit that determines the positions of the projection lens groups 131 and 132 in accordance with the focal lengths of the projection lens groups 131 and 132 included in the projection optical system 13 and the signal from the autofocus sensor 63 . A focus program 64 is implemented. The autofocus program 64 is called and executed by the exposure sequence program 90 each time a signal from the autofocus sensor 63 is input to the main controller 9 . The execution result of the autofocus program 64 is data of the arrangement position of each projection lens group 131, 132, and the exposure sequence program 90 sends this to the projection optical system 13 as a control signal. The projection optical system 13 includes a driving mechanism (not shown) that changes the arrangement positions of the projection lens groups 131 and 132, and the arrangement positions of the projection lens groups 131 and 132 are changed according to the sent control signal.

The direct drawing exposure apparatus of such an embodiment includes a suction mechanism 7 that suctions the work W to the work placement section at least when the work W passes through the exposure area. The adsorption mechanism 7 includes an adsorption box 71 and an exhaust system 72 for exhausting the interior of the adsorption box 71 .
FIG. 7 is a schematic side cross-sectional view showing adsorption of the work W by the adsorption mechanism 7. As shown in FIG.
As shown in FIG. 1, the suction box 71 is arranged in the circuit and positioned below the main transport path. The length of the suction box 71 is the length between the placement work position and the position slightly beyond the exposure area.

Each adsorption stage 3 has a large number of vacuum adsorption holes 30 . As shown in FIG. 7, the suction box 71 has an open top and forms a substantially closed space below the suction stage 3 positioned on the main transport path. The adsorption box 71 is connected to an exhaust source such as an exhaust blower or an exhaust pump through an exhaust pipe, and when the exhaust source operates, the inside of the adsorption box 71 becomes negative pressure (vacuum). Therefore, the workpiece W on the stage 3 positioned above is attracted to the stage 3 .
Since each stage 3 moves on the main transport path, a gap C is formed between the upper end of the suction box 71 and the lower surface of each stage 3 . This gap C is preferably about 1 to 5 mm. If it is larger than 5 mm, a sufficient negative pressure cannot be obtained, and the adsorption of the work W becomes insufficient. If the diameter is less than 1 mm, the revolving mechanism 21 is required to have a very high accuracy, resulting in an unnecessarily expensive mechanism.

The direct drawing exposure apparatus of this embodiment is used for the process of exposing both sides of the work W, and the next step is the exposure of the opposite side. Therefore, as shown in FIG. 1, a reversing machine 81 is installed adjacent to the unloading conveyor 50 . The reversing machine 81 is a mechanism that holds the work W vertically and turns it upside down. Further, ahead of the reversing mechanism 81, another direct drawing exposure apparatus having a similar configuration is installed.

Although such a direct writing exposure apparatus is assumed to be installed in a clean room, it is installed together with a clean bench mechanism 82 in this embodiment. A clean bench mechanism 82 is arranged above the apparatus and serves as a mechanism for down-flowing clean air. This is because the transfer system 2 includes mechanical driving parts and connecting parts such as the driving wheels 22 and the driven wheels 23, and dust is likely to be generated. Since the location where dust is likely to be generated is located below the work W to be conveyed, the dust is prevented from adhering to the work W by the flow from above.

Next, the operation of the direct drawing exposure apparatus of the embodiment will be described.
In the direct drawing exposure apparatus of the embodiment, the revolving mechanism 21 revolves each stage 3 at a constant speed during operation of the apparatus. The constant speed here is the speed determined by the relationship with each exposure by each exposure unit 1 as described above.
When the workpiece W is conveyed to the placement work position by the carry-in conveyor 40 , the loader 4 places the workpiece W on the stage 3 . At this time, the prealignment means operates to prealign the workpiece W. As shown in FIG. Therefore, it is placed on the stage 3 in a pre-aligned state. As shown in FIG. 1, in this embodiment, the length of the workpiece W in the transport direction is shorter than the length of the stage 3 in the same direction. For this reason, the workpiece W is placed across the front and rear stages 3 .

The work W placed on the stage 3 is transported along the main transport path by the movement of the stage 3 by the revolving mechanism 21 . Then, when passing under the imaging device 61 , the alignment mark is imaged by the imaging device 61 . Further, the autofocus sensor 63 measures the distance to the workpiece W when passing below the autofocus sensor 63 .
Then, the output of the imaging device 61 is input to the main control section 9, and the exposure pattern rewrite program 62 is executed to rewrite each exposure pattern program 91. FIG. The output of the autofocus sensor 63 is also input to the main controller 9, and control signals are sent to the projection optical systems 13 to adjust the positions of the projection lens groups 131 and 132. FIG.

In this state, when the work W reaches the exposure area, each exposure pattern program 91 controls the spatial light modulator 12 in each exposure unit 1, and the work W passes through the exposure area with a predetermined exposure pattern. Exposure is performed. The revolving mechanism 21 continues to operate at a constant speed, and when the work W passes the exposure area and reaches the collection work position, the unloader 5 operates at that timing to collect the work W from the carry-out stage 3 and transfer it to the carry-out conveyor 50. Transfer. Then, the carry-out conveyor 50 carries out the work W to the reversing mechanism 81, the reversing mechanism 81 turns over the work W, holds it again, and exposes the back surface of the work W by another direct writing type exposure (not shown) adjacent thereto. Send to device.

On the other hand, the next workpiece W is carried in the carry-in conveyor 40, and the same operation is repeated in parallel. That is, the placement on the stage 3 after pre-alignment, the imaging by the imaging element 61 while moving on the main transport path, the distance measurement by the autofocus sensor 63, and the exposure when passing through the exposure area are the same. is performed on In this manner, while the revolving mechanism 21 revolves the series of stages 3 at a constant speed, the loader 4 places the works W one by one, and the works W are sequentially passed through the exposure area for exposure.

In the direct drawing exposure apparatus of the embodiment, the stage 3 revolves along the endless circuit as described above, and the workpiece W is placed on the stage 3 at the timing when the stage 3 is positioned at the placement work position. Placement action is performed. Exposure is performed when the stage 3 passes through the exposure area, and then the work W is recovered from the stage 3 when it reaches the recovery work position. Since it is a simple mechanism that performs such a simple operation, it is possible to reduce the device cost. Further, the tact time is determined by the exposure in each exposure unit 1, and the transport operation of the work W does not determine the rate. Therefore, a practical apparatus is provided that can execute the exposure process with high productivity.

In addition, rewriting of the exposure pattern program 91 based on the imaging result of the imaging device 61 means that if the position of the work W is shifted when the imaging device 61 detects the workpiece W, the position is shifted similarly when the workpiece W passes through the exposure area. on the premise. In this case, correction may be performed on the assumption that the displacement (amount and direction) at the imaging position by the imaging element 61 and the displacement when passing through the exposure area are exactly the same, but it is assumed that they are different displacements with reproducibility. Sometimes corrections are made. In other words, there is a case where the correlation between the deviations caused by the detection elements 61 passing through the exposure area is checked in advance, and the exposure pattern program is rewritten in consideration of it.
The above point also applies to the autofocus means. In addition to the case where the distance measured by the autofocus sensor 63 is used as it is to control the projection optical system 13, there may be cases where the distance change is reproducible. That is, there is a difference between the distance when passing under the autofocus sensor 63 and the distance when passing through the exposure area. There may be a case where a control signal for autofocus is generated by taking into consideration.

In the above example, the main alignment is the alignment (alignment) of the light irradiation position of the exposure pattern, but it is also possible to correct the shape of the exposure pattern itself. For example, when the shape of the workpiece W is slightly distorted, exposure may be performed with an optimum exposure pattern according to the distortion. The distortion of the workpiece W can be determined by imaging a plurality of alignment marks and processing the image data, and the exposure pattern rewriting program 62 rewrites the exposure pattern program 91 according to the results. In addition to the distortion, if the dimensions of the work W are slightly different, the exposure pattern may be corrected accordingly. The fact that the dimensions of the work W are different from the reference value can be known by imaging a plurality of alignment marks and comparing the distance between them with the reference value. Therefore, as a result, the exposure pattern rewrite program 62 may enlarge or reduce the exposure pattern, and then perform exposure.
Although only one autofocus sensor 63 is shown in FIG. 1, a plurality of autofocus sensors 63 are actually provided. The distance measurement results obtained by the respective autofocus sensors 63 may be different. In this case, the distance between the measurement points is calculated from the measurement results (for example, by averaging).

In the above-described embodiment, the provision of the adsorption mechanism 7 for adsorbing the work W to the stage 3 is significant in that positional displacement of the work W is prevented and exposure with high positional accuracy is possible. That is, if the work W shifts after the imaging element 61 picks up an image of the alignment mark, it directly leads to a decrease in accuracy of the exposure position. Therefore, it is sufficient that the workpiece W is sucked at least between the detection position of the alignment mark by the imaging device 61 and the exposure area. However, if the alignment mark is out of the detectable range of the imaging device 61 due to positional deviation after pre-alignment, the alignment becomes impossible. more preferably.

Furthermore, the attraction of the workpiece W also has the significance of enabling exposure with high shape accuracy even when the workpiece W is warped or the like. For example, if the work W is a rigid printed circuit board, it may be slightly warped or otherwise deformed. In this case, if the work W is attracted to the stage 3 with a sufficient force, the deformation is eliminated by close contact with the stage 3, and exposure can be performed in this state. Therefore, regardless of the deformation, the exposure accuracy does not deteriorate. For this purpose, it is sufficient that the workpiece W is sucked to the stage 3 at least when passing through the exposure area.

It should be noted that there may be cases where no alignment mark is formed on the workpiece W, and the imaging device 61 may capture an image of something other than the alignment mark. For example, the alignment mark may output an alignment signal by imaging a circuit pattern already formed on the workpiece W, or may output an alignment signal by imaging the contour of the workpiece W itself. obtain.

In the above-described embodiment, the stage 3 is used as the work placement section, but in this respect, it is significant to improve the exposure accuracy by using a non-flexible member. Since the work placement part is a member that makes the posture of the work W optimal during exposure, when the work W passes through the exposure area, it is perpendicular to the optical axis of the exposure head and flat. It has to be posture. For this purpose, it is convenient to adopt a non-flexible member and configure the circulation mechanism 21 so that it is perpendicular to the optical axis during circulation. That is, adopting the stage 3, which is a member having no flexibility, as the work mounting portion has the significance of simplifying the configuration in order to hold the posture of the work W during exposure.

It is also possible to use a flexible member and a work placement section, for example, it can be used as a flexible belt work placement section. Conveying belts made of steel such as stainless steel are commercially available, and are suitable for use because they generate less dust. In addition, a conveyor belt made of resin such as fluororesin may also be used.

As for the structure of the drive wheel 22 and the driven wheel 23 in the revolving mechanism 21, in addition to meshing with meshing teeth as described above, a structure in which the work placement portion is revolved by frictional force is also possible. This configuration is particularly possible when the flexible member is used as a work. Furthermore, magnetic force may be used to transmit force between the driving portion and the workpiece placement portion. That is, it is also possible to employ a configuration in which the drive wheel and the work placement section are magnetically coupled, and the work placement section is rotated by rotating the drive wheel.

It is preferable to adjust the tension in the revolving mechanism 21 in order to maintain a flat posture perpendicular to the optical axis of the exposure head in the exposure area. For example, when a flexible member as described above is used as the work placement section, if the work W becomes slack when passing through the exposure area, the posture of the work W changes and the exposure accuracy decreases. Therefore, it is preferable that an appropriate tension is applied to the work placement portion at least when passing through the exposure area. As a configuration for this purpose, it can be achieved by applying an appropriate reverse torque to the driven wheel 23 . That is, when the drive wheel 22 rotates and pulls the work placement portion, reverse torque is applied to the driven wheel 23, and the drive wheel 22 rotates against it.

The above configuration is effective even in the case of a structure such as the stage 3 in which inflexible work placement portions are connected. A structure in which non-flexible members are connected may have backlash at the connecting portion. Due to the influence of this backlash, the work placement section may be slightly tilted in the exposure area, which may reduce the exposure accuracy. In order to prevent this, a reverse torque is applied to the driven wheel 23 in the same manner so that the workpiece mounting portion is pulled from both sides.

In the operation of the above-described direct drawing exposure apparatus, the revolving mechanism 21 revolves each stage 3 at a constant speed, and the movement does not stop during normal operation of the apparatus. However, a sequence that stops at an appropriate timing may be adopted as necessary. For example, when prealigning the work W and placing it on the stage 3, it may be easier to stop the work W, and in that case, the operation of the rotation mechanism 21 may be temporarily stopped. . After placing the work W in the pre-aligned state, the rotation mechanism 21 resumes its operation. Also, there are cases where it is better to stop even when the imaging element 61 is imaging, and in that case, there are cases where the movement is temporarily stopped. When the movement is temporarily stopped in this way, the work W should not be positioned in the exposure area at that timing. This is because it becomes difficult to control the exposure time (the amount of light) if it is located in the exposure area. Conversely, the configuration in which the workpiece W does not stop has the significance that the control of the spatial light modulator 12 in the exposure unit 1 does not become complicated.

In the above embodiments, the alignment configuration is changed as appropriate. For example, when the necessary positional accuracy is ensured only by pre-alignment, the main alignment is not performed and the imaging element 61 and the like are not provided.
Also, autofocusing means may be unnecessary if the accuracy of the transport system 2 is sufficiently high. That is, if the transport system 2 is a mechanism capable of transporting the work W sufficiently horizontally in relation to the depth of focus of the projection optical system 13 and the necessary exposure contrast, the autofocus means may be unnecessary. .

Although a plurality of exposure units 1 are provided in the above embodiment, there may be cases where only one exposure unit 1 is provided. Further, in the case of a single-sided exposure process, the reversing mechanism 81 is not provided, and another adjacent direct writing type exposure device is not provided.
Moreover, the work W may be a flexible sheet-like member as well as a rigid plate-like member. It is typically a flexible printed circuit board.
Furthermore, as an exposure process, in addition to the purpose of circuit formation such as a printed circuit board, exposure may be performed for the purpose of building a mechanical fine structure such as MEMS. The device can be used in a variety of such applications.

1 Exposure Unit 2 Transport System 21 Revolving Mechanism 22 Driving Wheel 23 Driven Wheel 3 Stage 4 Loader 5 Unloader 61 Imaging Element 62 Exposure Pattern Rewriting Program 63 Autofocus Sensor 64 Autofocus Program 7 Vacuum Suction Mechanism 71 Suction Box 81 Reversing Mechanism 82 Clean Bench mechanism 9 Main controller 90 Exposure sequence program W Work

Claims (7)

A direct writing exposure apparatus that irradiates and exposes a plate-like or sheet-like work with light of a predetermined pattern without a mask,
an exposure head that irradiates a predetermined pattern of light onto a set exposure area;
and a transport system that transports the workpiece through the exposure area,
The workpiece transfer system is
a circulation mechanism that rotates the work placement section, which is in a flat posture perpendicular to the optical axis of the exposure head when passing through the exposure area, along an endless circulation circuit;
a loader for placing an unexposed work on the work placement section;
A direct drawing exposure apparatus comprising an unloader for recovering an exposed workpiece from a workpiece placement section. An alignment sensor is provided at a position for detecting the state of the work on the peripheral circuit between the exposure area and the placement work position where the loader places the unexposed work,
2. A direct drawing exposure apparatus according to claim 1, further comprising alignment means for correcting the irradiation position of said predetermined pattern of light by said exposure head according to a signal from an alignment sensor. 3. The direct writing exposure system according to claim 2, wherein said alignment means is means for correcting said irradiation position based on a signal from said alignment sensor that detects the state of said workpiece while it is moving on said circuit. Device. The exposure head includes a projection optical system that forms the predetermined pattern of light,
An autofocus sensor for measuring a distance to the work placed on the work placement unit is provided on the peripheral circuit between the exposure area and the placement work position where the loader places an unexposed work . is provided,
4. A direct drawing exposure apparatus according to claim 1, further comprising autofocus means for controlling the projection optical system according to the measurement result of the autoforce sensor. 5. A method according to claim 4, wherein said autofocus means is means for controlling said projection optical system in accordance with a signal from said autofocus sensor that measures a distance to said work moving on said circuit. Direct writing exposure equipment. 2. The direct drawing exposure system according to claim 1, further comprising a suction mechanism for sucking the work mounted on the work mounting portion to the work mounting portion at least when the work passes through the exposure area. Device. 4. A suction mechanism for sucking the workpiece, whose state is detected by the alignment sensor, to the workpiece placement unit from at least the time of detection until the workpiece passes through the exposure area. Direct writing exposure apparatus as described.

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