CN111856886A

CN111856886A - Direct writing type exposure device

Info

Publication number: CN111856886A
Application number: CN202010331754.0A
Authority: CN
Inventors: 渡边健二
Original assignee: Adtec Engineering Co Ltd
Current assignee: Adtec Engineering Co Ltd
Priority date: 2019-04-26
Filing date: 2020-04-24
Publication date: 2020-10-30
Also published as: JP2020181132A; JP7196011B2; TW202043845A; KR20200125485A

Abstract

The invention provides a direct-writing type exposure device which can realize low cost by a simple structure and can execute an exposure process with high productivity. A plurality of stages (3) as workpiece placing parts are connected and rotated along an annular circulating path by a rotating mechanism (21). An unexposed workpiece W is placed on a loader (4) on a stage (3) which has reached a placing position, and when the workpiece W passes through an exposure area by the movement of the stage (3), the exposure head (1) irradiates the exposure area with light of an exposure pattern to expose the workpiece W. The work W is adsorbed on the stage 3 by an adsorption mechanism 7, and the irradiation position of the exposure pattern is corrected by an alignment unit. The exposed work W is recovered by an unloader (5).

Description

Direct writing type exposure device

Technical Field

The present invention relates to a direct writing type exposure apparatus that exposes a workpiece without irradiating the workpiece with light of a predetermined pattern through a mask. Hereinafter, the predetermined pattern of light during exposure is referred to as an exposure pattern.

Background

An exposure technique for exposing an object having a photosensitive layer formed on a surface thereof to light and then exposing the photosensitive layer is widely used as a main technique of photolithography for forming various fine circuits, fine structures, and the like. Representative exposure techniques are the following: the mask having the same pattern as the exposure pattern is irradiated with light, and the image of the mask is projected onto the surface of the object, thereby irradiating the object with the light of the exposure pattern.

Unlike an exposure technique using such a mask, a technique of directly forming an image on the surface of an object using a spatial light modulator and exposing the image is known. Hereinafter, this technique is referred to as direct exposure in the present specification.

In direct-write exposure, a typical spatial light modulator is a DMD (Digital Mirror Device). The DMD has a structure in which minute square mirrors are arranged in a right-angle grid. The angles of the respective mirrors with respect to the optical axis are independently controlled, and a posture in which the light from the light source is reflected to reach the object and a posture in which the light from the light source does not reach the object can be assumed. The DMD includes a controller for controlling each mirror, and the controller controls each mirror in accordance with an exposure pattern so that light of the exposure pattern is irradiated onto the surface of an object.

In the case of direct exposure, since a mask is not used, it is advantageous in mass production of various products. In the case of exposure using a mask, it is necessary to prepare a mask for each type, and a large cost is required including costs for storing the mask. Further, when the mask is replaced for producing a different type of product, the operation of the apparatus needs to be stopped, and time and effort are required until the operation is restarted. Therefore, this causes a reduction in productivity. On the other hand, in the case of direct writing exposure, only the control program for each mirror needs to be prepared for each product type, and in the case of manufacturing different product types, it is possible to cope with this by merely changing the control program, and therefore, the advantages in terms of cost and productivity are significant. Further, the exposure pattern can be finely adjusted for each workpiece (exposure object) as needed, and the process flexibility is also excellent.

In such a direct-write exposure apparatus, a stage on which a workpiece is placed is used in order to orient the workpiece perpendicular to an optical axis of an exposure unit incorporating a spatial light modulator. The exposure unit irradiates a set region (hereinafter referred to as an exposure region) with light of an exposure pattern, and a stage on which a workpiece is placed moves through the exposure region by a transport system, thereby exposing the workpiece while passing through the exposure region.

In such a direct-writing type exposure apparatus, a dual stage structure in which two stages are mounted is often employed to improve productivity. The structure disclosed in patent document 1 is also an example thereof. In the dual stage structure, stages are disposed on both sides of an exposure region, and the stages on which a workpiece is placed alternately pass through the exposure region, thereby performing exposure. In this case, a loading (placing)/unloading (collecting) mechanism is provided on one side of the exposure area, and a loading/unloading mechanism is also provided on the other side.

Patent document 1: japanese patent laid-open No. 2008-191303

In the direct-writing type exposure apparatus, it is often required to expose both sides of the workpiece. In the case of exposing both sides, two direct type exposure apparatuses are provided in the vertical direction, and after one side is exposed by the first stage, the other side is exposed by the second stage. A turnover mechanism for turning over the workpiece is arranged between the first device and the second device.

In the case where two direct-writing type exposure apparatuses are provided in the vertical direction, the configuration of the two stages is also changed. One side of the exposure area is dedicated for loading, and the other side is dedicated for unloading. And the unloading mechanism on the other side transfers the exposed workpiece to the turnover mechanism, and the turnover mechanism turns over the front side and the back side and transfers the turned workpiece to the loading mechanism of the second direct writing type exposure device.

The two stages are alternately moved to the loading position because the workpiece is loaded only on one side. The stage on which the workpiece is placed at the loading position moves to the other side through the exposure area for exposure, and after the workpiece is taken away, returns to the one side, and places the workpiece again. The two stages are formed in a cantilever structure facing each other 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 conveying direction, and the other stage is held by an arm extending from the right side. The arms are respectively connected with a lifting mechanism, and when one objective table moves along the conveying line, the objective table is constructed to retreat to the upper side or the lower side without interference.

As described above, the direct writing type exposure apparatus having the dual stages mounted with the two stages has a significantly improved productivity as compared with an apparatus having only one stage. However, the structure is complicated and easily enlarged, which tends to result in high cost. This problem is significant in a configuration in which one side is dedicated to loading and the other side is dedicated to unloading.

Further, since the other stage cannot move forward on the conveying line until the retraction operation of the one stage is completed, the tact time may be limited in this portion. This hinders the advantages of the dual stage, and the productivity is not greatly improved.

Disclosure of Invention

The present invention has been made to solve the problem of productivity of such a direct-writing exposure apparatus, and an object thereof is to provide a direct-writing exposure apparatus which has a simple structure, can be manufactured at low cost, and can perform an exposure process with high productivity.

In order to solve the above problems, a direct-writing exposure apparatus according to the present invention is a direct-writing exposure apparatus that irradiates a plate-shaped or sheet-shaped workpiece with light having a predetermined pattern without a mask to perform exposure, and includes an exposure head that irradiates a set exposure area with light having a predetermined pattern, and a transport system that transports the workpiece through the exposure area. The work transfer system includes a circling mechanism for circling a work placing part in a posture which is perpendicular to and flat with respect to an optical axis of the exposure head along an annular circling path when passing through the exposure area, a loader for placing an unexposed work on the work placing part, and an unloader for recovering an exposed work from the work placing part.

In order to solve the above problem, the direct writing type exposure apparatus has the following configuration: an alignment sensor is provided at a position for detecting a state of a workpiece on a circumferential path between a mounting work position at which an unexposed workpiece is mounted on a loader and an exposure area, and an alignment means for correcting an irradiation position of light based on a predetermined pattern of an exposure head based on a signal from the alignment sensor is provided.

In order to solve the above problem, the alignment means corrects the irradiation position using a signal from an alignment sensor that detects the state of the workpiece moving on the loop.

In order to solve the above-described problems, the direct writing exposure apparatus is configured such that the exposure head includes a projection optical system for forming light of a predetermined pattern, an autofocus sensor for measuring a distance to the workpiece placed on the workpiece placement portion is provided on a circumferential path between the placement work position and the exposure area, and an autofocus unit for controlling the projection optical system based on a measurement result measured by the autofocus sensor is provided.

In order to solve the above problem, the autofocus unit is a unit that controls the projection optical system based on a signal from an autofocus sensor that measures a distance to a workpiece moving on a circulating path.

In order to solve the above problem, the direct writing exposure apparatus includes an adsorption mechanism that adsorbs a workpiece placed on a workpiece placement portion when the workpiece passes through an exposure region.

In order to solve the above problem, the direct writing exposure apparatus may further include an adsorption mechanism that adsorbs the workpiece, whose state is detected by the alignment sensor, onto the workpiece placement unit at least from the time of the detection until the workpiece passes through the exposure area.

The invention has the following effects:

as described below, according to the direct writing type exposure apparatus of the present invention, when the stage that revolves along the endless revolving path is located at the mounting work position, the mounting operation of the workpiece on the stage is performed, and when the stage passes through the exposure area, the exposure is performed, and then, the simple operation of collecting the workpiece from the stage when the stage reaches the collection work position is performed, so that the apparatus cost can be reduced. In addition, the speed of the production tact time is limited by the exposure in the exposure unit, and is not limited by the work conveyance operation. Therefore, a practical apparatus capable of performing an exposure process with high productivity is provided.

Further, by detecting the state of the workpiece on the loop between the mounting work position and the exposure area and correcting the irradiation position of the exposure pattern based on the state, it is possible to irradiate the exposure pattern with light at a correct position even if the workpiece is arranged on the workpiece mounting portion with a displacement. Therefore, exposure with higher positional accuracy can be performed.

Further, if the alignment means is a means for correcting the irradiation position of the exposure pattern by a signal from an alignment sensor that detects the state of the workpiece moving on the circulating path, it is not necessary to stop the operation of the revolving mechanism in order to detect the state of the workpiece, and the control of the exposure means does not become complicated.

In addition, in the configuration in which the autofocus sensor measures the distance to the workpiece on the loop between the placement work position and the exposure area and performs autofocus control on the projection optical system based on the result, a clearer exposure pattern is irradiated on the workpiece, and therefore, exposure with higher accuracy can be performed. In this case, in the configuration in which the autofocus sensor measures the distance to the workpiece moving on the loop path, it is not necessary to stop the operation of the swivel mechanism in order to measure the distance, and the control of the exposure unit does not become complicated.

In addition, in the configuration in which the workpiece placed on the workpiece placing portion is adsorbed on the workpiece placing portion when the workpiece passes through at least the exposure region, even when the workpiece is deformed such as warped, the exposure is performed in a state in which the deformation is eliminated. Therefore, exposure processing with higher accuracy can be performed.

In addition, in the configuration in which the workpiece is attracted to the workpiece placement unit from the time of detection based on the state of the alignment sensor until the workpiece passes through the exposure area, the position is shifted in the middle of conveyance, and thus the accuracy of the irradiation position of the exposure pattern is not lowered. Therefore, the exposure process can be performed with higher accuracy in this point.

Drawings

Fig. 1 is a schematic front view of a direct type exposure apparatus according to an embodiment.

Fig. 2 is a schematic plan view of the direct type exposure apparatus according to the embodiment.

Fig. 3 is a schematic diagram of an exposure unit in the direct writing exposure apparatus according to the embodiment.

Fig. 4 is a schematic perspective view showing an exposure region.

Fig. 5 is a schematic perspective view of a swivel mechanism provided in the conveyance system.

Fig. 6 is a schematic perspective view showing a connection structure of each station.

Fig. 7 is a schematic side cross-sectional view showing the suction of the workpiece by the suction mechanism.

Description of the symbols:

1 Exposure Unit

2 conveying system

21 circle mechanism

22 drive wheel

23 driven wheel

3 object stage

4 loader

5 unloading machine

61 image pickup element

62 Exposure pattern rewriting program

63 automatic focusing sensor

64 auto-focusing program

7 vacuum adsorption mechanism

71 adsorption tank

81 turnover mechanism

82 ultra-clean workbench mechanism

9 Main control part

90 Exposure sequence program

W workpiece

Detailed Description

Next, a mode for carrying out the invention of the present application (hereinafter, referred to as an embodiment) will be described.

Fig. 1 and 2 are schematic views of a direct type exposure apparatus according to an embodiment, fig. 1 being a front schematic view, and fig. 2 being a plan schematic view. The direct-writing exposure apparatus shown in fig. 1 and 2 includes an exposure unit 1 that irradiates an exposure area with light of an exposure pattern, and a conveyance system 2 that conveys a workpiece W through the exposure area.

In this embodiment, the workpiece W has a plate shape. More specifically, in this embodiment, the direct type exposure apparatus is an apparatus for manufacturing a printed circuit board, and therefore the workpiece W is a substrate for a printed circuit board. As the printed circuit board, a sheet-like flexible board is also known, but in this embodiment, the flexible board is a rigid board made of a resin such as polyimide.

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

The light source 11 is a light source that outputs light of an optimal wavelength according to the light-sensitive wavelength of the photosensitive layer in the workpiece W. The photosensitive wavelength of the resist film is often in the range from the visible short wavelength region to the ultraviolet region, and a light source that outputs light in the ultraviolet region from the visible short wavelength region such as 405nm or 365nm is used as the light source 11. In order to effectively utilize the performance of the spatial light modulator 12, it is preferable to output coherent light, and therefore, a laser light source is preferably used. For example, a gallium nitride (GaN) semiconductor laser is used.

In the present embodiment, a DMD is used as the spatial light modulator 12. As described above, in the DMD, each pixel is a minute mirror (not shown in fig. 2). The 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 plurality of pixel mirrors are arranged in a rectangular grid. The number of arrays is, for example, 1024 × 768.

The spatial light modulator 12 includes a modulator controller 121 that controls each pixel mirror. The direct-writing exposure apparatus according to the embodiment includes a main control unit 9 that controls the entire apparatus. The modulator controller 121 controls each pixel mirror in accordance with a signal from the main control section 9. Each pixel mirror can take a first posture along the reference plane and a second posture inclined at an angle of, for example, about 11 to 13 ° with respect to the reference plane, with the plane on which the pixel mirrors are arranged as the reference plane. In the present embodiment, the first posture is the closed state, and the second posture is the open state.

The spatial light modulator 12 includes a driving mechanism that drives each pixel mirror, and the modulator controller 121 can independently control whether each pixel mirror takes the first posture or the second posture. Such a spatial light modulator 12 is available from Texas Instruments Inc ("Texas Instruments Inc," also known as "テキサス · インスツルメンツ, japanese).

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, the illumination optical system 14 includes an optical fiber 141. In order to form an image with higher illuminance, one exposure unit 1 includes 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 quartz multimode fiber is used.

In order to perform high-precision imaging using the spatial light modulator 12 as a DMD, it is preferable to make parallel light incident and reflect by each pixel mirror, and to make light incident obliquely with respect to each pixel mirror. Therefore, as shown in fig. 3, the irradiation optical system 14 includes a collimator lens 142 for making the light emitted from each optical fiber 61 and diffused into parallel light, and a mirror 143 for making the light obliquely incident on the spatial light modulator 12. "tilt" refers to tilting with respect to the reference plane of the spatial light modulator 12. The incident angle with respect to the reference plane is, for example, an angle of about 22 to 26 °.

The projection optical system 13 is constituted by two

projection lens groups

131 and 132, and a microlens array (hereinafter abbreviated as MLA) 133 and the like disposed between the

projection lens groups

131 and 132. The MLA133 is disposed supplementarily for performing exposure with higher shape accuracy. The MLA133 is an optical component in which a plurality of fine lenses are arranged in a rectangular grid. Each lens element corresponds to each pixel mirror of the spatial light modulator 12.

In the exposure unit 1, light from the light source 11 is guided by the optical fiber 141 and then enters the spatial light modulator 12 through the illumination 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 in accordance with the exposure pattern to be formed. That is, according to the exposure pattern to be formed, the pixel mirror located at the position where light should reach the exposure region is set to the second posture (on state), and the other pixel mirrors are set to the first posture (off state). The light reflected by the pixel mirror in the off state does not reach the exposure region, and only the light reflected to the pixel mirror in the on state reaches. Therefore, light of a predetermined exposure pattern is irradiated to the exposure region.

A control signal is sent from the main control section 9 to each modulator controller 121 to realize a predetermined exposure pattern. The control signal is a sequence that drives each pixel mirror. In the main control section 9, a program 91 including each sequence transmitted to each modulator controller 121 is stored in the storage section 900 of the main control section 9 in order to realize a predetermined exposure pattern. Hereinafter, this procedure will be referred to as an exposure pattern procedure 91. The exposure pattern program 91 is prepared in advance based on design information on what kind of circuit is 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, 8 exposure heads 1 are provided in this embodiment. By 8 exposure heads 1, one exposure pattern is formed as a whole. The exposure heads 1 have the same configuration.

The exposed area is supplemented with reference to fig. 4. Fig. 4 is a schematic perspective view showing an exposure region. In fig. 4, a region (hereinafter, referred to as an individual region) E in which 1 exposure head 1 can irradiate light is indicated by a square frame. The collection of individual areas E is an exposure area.

The workpiece W receives light irradiation in each individual region E while moving in the direction indicated by the arrow (conveyance direction) in fig. 4. At this time, since the two rows of exposure heads 1 are arranged offset from each other, exposure is performed without a gap in the horizontal direction perpendicular to the conveyance direction.

Actually, in each individual region E, there is a set of minute irradiation patterns (hereinafter, referred to as minute patterns). The 1 minute pattern is a pattern formed by the 1 pixel mirror 31. The workpiece W placed on the stage 3 moves in the exposure area in accordance with the movement of the stage 3, and the opening and closing of the micro pattern are performed in a predetermined sequence in accordance with the timing of the movement. Thereby, a desired exposure pattern is formed on the workpiece W.

Next, the conveyance system 2 will be explained.

The direct writing exposure apparatus of the present embodiment is largely characterized by using a turret mechanism 21 for rotating a member (workpiece placing portion) on which a workpiece W is placed along an annular circular path. Specifically, in the present embodiment, the workpiece placing section is the stage 3. The stage 3 is a table-like member having a low height. As shown in fig. 1, the swivel mechanism 21 is a mechanism for swiveling the stage 3 in a vertical plane.

Fig. 5 is a schematic perspective view of the turning mechanism 21 provided in the conveying system 2. Fig. 6 is a schematic perspective view showing a connection structure of each station. In the following description, the traveling direction of each stage 3 in the detour is defined as the front-rear direction, and the horizontal direction perpendicular thereto is defined as the left-right direction.

As shown in fig. 1 and 5, the plurality of stages 3 are arranged along a circular path. Although not shown in fig. 5, as shown in fig. 6, the stages 3 are coupled to each other by a coupling unit 31. Each stage 3 has a connecting portion 32 in the front and rear. Each coupling portion 32 is a portion extending forward and rearward from the stage 3. The coupling portions 32 are provided on the left and right sides, and four in total. In this embodiment, the coupling member 31 is a coupling pin. Each coupling portion 32 is formed with a pin insertion hole, and couples the stages 3 by inserting a coupling pin through the pin insertion hole.

In each stage 3, a pair of rear connecting portions 32 are provided, and one front connecting portion 32 is provided. The front coupling portions 32 of the stages 3 are inserted between the rear coupling portions 32 of the stages 3 in front, and are coupled by the coupling members 31 in this state.

As shown in fig. 5, the swivel mechanism 21 includes a pair of drive wheels 22 and a pair of driven wheels 23. The pair of drive wheels 22 are disposed on the front side on the loop road. The pair of drive wheels 22 are fixed to a drive shaft 221 extending in the left-right direction, and a drive source, not shown, is connected to the drive shaft 221. The pair of driven wheels 23 is disposed on the rear side on the circumferential path. The pair of driven pulleys 23 is fixed or coupled to a driven shaft 231 extending in the left and right direction.

Each stage 3 has a plurality of engagement holes 34 formed in the lateral side portions thereof. As shown in fig. 5, each of the driving wheels 22 and each of the driven wheels 23 is in a gear shape and has meshing teeth. The engaging holes 34 are formed in a size and shape suitable for the engaging teeth. When the pair of drive wheels 22 is driven to rotate by a drive source, not shown, the engaging teeth sequentially engage with the engaging holes 34, and the coupled stages 3 are moved along the circulating path. At this time, the respective meshing teeth of the driven pulley 23 are also driven while sequentially meshing with the respective meshing holes 34. In this way, each stage 3 makes a turn along the loop.

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

The carry-in conveyor 40 is located at a place where the loader 4 is installed. The loader 4 includes a loading robot part 42 having a suction pad 41, and a loading-side robot driving mechanism 43 for moving the loading robot part 42 up and down, back and forth, and left and right. The suction pads 41 are provided in plural downward postures, and can suction and hold the workpiece W by vacuum suction.

The carry-out conveyor 50 for conveying the workpiece W in the next step is located at a place where the unloader 5 is installed. The unloader 5 also includes a carry-out robot 52 having a suction pad 51 and a carry-out robot driving mechanism 53 for moving the carry-out robot 52 up and down, back and forth, and left and right, as in the loader 4.

As understood from the above description, each stage 3 is turned by the turning mechanism 21, but the period in which the workpiece W is placed on the stage 3 is a period in which the upper portion of the peripheral path shown in fig. 1 moves. During this time, the workpiece W is exposed through the exposure region. Hereinafter, the upper portion of the circulating path is referred to as a main conveyance path. The position where the loader 4 performs the operation of placing the workpiece W is referred to as a placing operation position, and the position where the unloader 5 performs the operation of collecting the workpiece W is referred to as a collecting operation position.

The speed of the circling movement of each stage 3 by the circling mechanism 21 is limited by the exposure performed by each exposure unit 1. That is, as described above, each exposure pattern program 91 is installed for each exposure unit 1, but the sequence of opening and closing of each pixel mirror here assumes that the workpiece W moves at a constant speed. The speed is predetermined in accordance with the relationship with the required exposure amount, and on the premise that this speed is predetermined, each exposure pattern program 91 is programmed. Then, a control signal is transmitted to the rotation mechanism 21 so that the rotation is performed at the constant speed.

The direct type exposure apparatus of the embodiment is provided with a mechanism for improving the pattern accuracy of the exposure process. Specifically, an alignment unit that corrects an exposure pattern according to the state of the workpiece W when conveyed to the exposure area, and an autofocus unit that controls the projection optical system 13 to sharpen the exposure pattern are provided.

First, the alignment unit is explained, and the alignment unit includes a pre-alignment unit and a formal alignment unit. The pre-alignment unit is a unit for adjusting the mounting position of the workpiece W for the final alignment. The formal alignment unit is a unit that corrects an exposure pattern according to the state of the workpiece W.

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

In this embodiment, the pre-alignment unit is a unit for performing alignment mechanically. The purpose of the pre-alignment is that each alignment mark enters the field of view (imageable range) of the imaging element 61 while the workpiece W is conveyed along the main conveyance path. Although not shown, the pre-alignment unit includes a shutter fixed at a predetermined position in a predetermined posture. The baffle is, for example, a 90-degree band plate-shaped member, and is disposed so that the width direction is the vertical direction. The pre-alignment is performed using the carry-in robot hand 42. That is, the carry-in hand 42, when holding the workpiece W, abuts against the fence, and in this state, holds the workpiece W again in a predetermined positional relationship. Thereby performing pre-alignment.

As shown in fig. 1, the image pickup device 61 is positioned above the main conveyance path. This position is a position where the alignment mark of the workpiece W moved on the main conveying path enters the field of view. In other words, the workpiece W is pre-aligned by the pre-alignment unit so that the alignment mark comes within the range of the field of view of the image pickup element 61 while moving on the main conveying path.

The main alignment is an operation of determining the state of the workpiece W by the image pickup device 61 and changing the exposure pattern according to the state. The "state of the workpiece W" includes the position of the workpiece 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 (the light irradiation position of the exposure pattern) is changed in accordance with the position. That is, it is determined in which direction the position of the workpiece W when passing through the exposure area is shifted from the reference position based on the data from the image pickup device 61, and the formation position of the exposure pattern is changed in accordance with the determined position. The change of the formation position of the exposure pattern is performed as a change (rewrite) of the exposure pattern program 91. The formal alignment means includes an exposure pattern rewriting program 62 installed in the main control section 9. The exposure pattern rewriting program 62 processes data from each image pickup device 61, calculates a position where an exposure pattern is formed, and rewrites the exposure pattern program 91 with the result. Further, since the image pickup device 61 picks up an image of the alignment mark of the workpiece W moving on the main conveying path, actually, data of an appropriate still image is extracted from the moving image data and processed to determine a deviation between the position of the workpiece W and the reference position.

The main control unit 9 is provided with an exposure sequence program 90 for causing each unit of the apparatus to operate in a predetermined sequence. Each time a signal is output from each imaging element 61, the exposure pattern rewriting program 62 is called from the exposure sequence program 90 and executed.

Next, the autofocus unit will be explained.

The autofocus unit includes an autofocus sensor 63 and an autofocus program 64 that generates a control signal for the projection optical system 3 based on a signal from the autofocus sensor 63. The autofocus unit is a unit that controls the projection optical system 13 according to the distance (distance in the optical axis direction) from the projection optical system 13 to the workpiece W when passing through the exposure area. In this embodiment, the autofocus sensor 63 is a distance meter disposed on the main conveyance path immediately before the exposure area. A laser range finder or the like using laser interference is used as the sensor 63 for auto focusing. The autofocus sensor 63 is disposed above the main conveyance path, and measures the distance to the workpiece W at a position slightly before reaching the exposure area.

The main control unit 9 is provided with an auto-focus program 64, and the auto-focus program 64 determines the arrangement position of each of the

projection lens groups

131 and 132 based on the focal length of each of the

projection lens groups

131 and 132 included in the projection optical system 13 and a signal from the auto-focus sensor 63. Each time a signal from the autofocus sensor 63 is input to the main control section 9, the exposure sequence program 90 calls up and executes the autofocus program 64. The execution result of the autofocus program 64 is data of the arrangement position of each

projection lens group

131, 132, which the exposure sequence program 90 sends to the projection optical system 13 as a control signal. The projection optical system 13 includes a driving mechanism, not shown, for changing the arrangement position of each

projection lens group

131 and 132, and changes the arrangement position of each

projection lens group

131 and 132 in accordance with the transmitted control signal.

The direct writing exposure apparatus of the embodiment described above includes at least the suction mechanism 7 for sucking the workpiece W to the workpiece mounting portion when the workpiece W passes through the exposure region. The adsorption mechanism 7 includes an adsorption tank 71 and an exhaust system 72 for exhausting the inside of the adsorption tank 71.

Fig. 7 is a schematic side sectional view showing the suction mechanism 7 sucking the workpiece W. That is, fig. 7 is a schematic cross-sectional view in the left-right direction.

As shown in fig. 1, the suction box 71 is disposed in the loop path and below the main conveyance path. The length of the suction box 71 is a length between the mounting work position and a position slightly beyond the exposure area.

Each adsorption stage 3 has a plurality of vacuum adsorption holes 30. As shown in fig. 7, the suction box 71 is open at the upper side and forms a substantially closed space below the suction stage 3 positioned on the main conveyance path. The adsorption tank 71 is connected to an exhaust source such as an exhaust blower or an exhaust pump via an exhaust pipe, and when the exhaust source is operated, the inside of the adsorption tank 71 becomes a negative pressure (vacuum). Therefore, the workpiece W on the upper stage 3 is attracted to the stage 3.

Since each stage 3 moves on the main conveyance path, a gap C is formed between the upper end of the suction box 71 and the lower surface of each stage 3. The clearance C is preferably about 1 to 5 mm. If the thickness exceeds 5mm, a sufficient negative pressure cannot be obtained, and the work W cannot be sufficiently sucked. If the diameter is less than 1mm, a very high accuracy is required as the structure of the swivel mechanism 21, which results in an unnecessarily expensive mechanism.

In addition, the direct writing type exposure apparatus of this embodiment is used for a process of exposing both surfaces of the workpiece W, and the next step is exposure of the opposite surface. Therefore, as shown in fig. 1, the inverting machine 81 is provided adjacent to the carry-out conveyor 50. The inverting machine 81 is a mechanism for vertically inverting the workpiece W while vertically holding the workpiece W. Further, another direct type exposure apparatus having the same configuration is provided in front of the reversing mechanism 81.

It is assumed that such a direct type exposure apparatus is installed in a clean room, and particularly in this embodiment, is installed together with the clean bench mechanism 82. The clean bench mechanism 82 is disposed above the apparatus, and serves as a mechanism for allowing clean air to flow downward. This is because the conveying system 2 includes a structural driving portion and a coupling portion such as the driving wheel 22 and the driven wheel 23, and dust is easily blown. Since the portion where dust is likely to be blown out is located below the workpiece W to be conveyed, dust is not attached to the workpiece W by the blower from above.

Next, the operation of the direct writing exposure apparatus according to the embodiment will be described.

In the direct-writing exposure apparatus of the embodiment, the turret mechanism 21 revolves each stage 3 at a constant speed during operation of the apparatus. The constant speed here is a speed limited in accordance with the relationship with each exposure of each exposure unit 1 as described above.

When the workpiece W is carried to the loading operation position by the carry-in conveyor 40, the loader 4 loads the workpiece W on the stage 3. At this time, the prealignment unit operates to prealign the workpiece W. Therefore, the object is placed on the stage 3 in a pre-aligned state. In addition, as shown in fig. 1, in this embodiment, the length of the workpiece W in the conveying direction is shorter than the length of the stage 3 in the same direction. Therefore, the workpiece W is placed on the plurality of stages 3 before and after the workpiece W.

The workpiece W placed on the stage 3 is conveyed along the main conveyance path by the movement of the stage 3 by the turret mechanism 21. When the alignment mark passes below the imaging device 61, the alignment mark is imaged by the imaging device 61. When the workpiece W passes below the autofocus sensor 63, the autofocus sensor 63 measures the distance to the workpiece W.

Then, the output of the imaging device 61 is input to the main control section 9, and the exposure pattern rewriting program 62 is executed to rewrite each exposure pattern program 91. The output of the autofocus sensor 63 is also input to the main control unit 9, and a control signal is sent to each projection optical system 13 to adjust the arrangement position of each

projection lens group

131, 132.

In this state, when the workpiece W reaches the exposure area, the spatial light modulator 12 in each exposure unit 1 is controlled by each exposure pattern program 91, and when the workpiece W passes through the exposure area, exposure is performed in a predetermined exposure pattern. Next, the turret mechanism 21 continues to operate at a constant speed, and when the workpiece W passes through the exposure region and reaches the collection work position, the unloader 5 operates at that time, and collects the workpiece W from the carry-out stage 3 and mounts it on the carry-out conveyor 50. Then, the carry-out conveyor 50 carries the workpiece W out to the reversing mechanism 81, and the reversing mechanism 81 reverses the workpiece W and holds it again, and conveys it to another adjacent direct-writing exposure apparatus, not shown, in order to expose the surface on the back side.

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 mounting of the mounting table 3 after the pre-alignment, the imaging by the imaging element 61 while moving on the main conveyance path, the distance measurement by the autofocus sensor 63, and the exposure when passing through the exposure area are performed in the same manner. In this way, the workpieces W are placed one by the loader 4 while the circling mechanism 21 revolves the series of stages 3 at a constant speed, and the workpieces W are exposed sequentially through the exposure area.

In the direct-writing type exposure apparatus according to the embodiment, as described above, the stage 3 is rotated along the annular loop path, and the operation of placing the workpiece W on the stage 3 is performed at the timing when the stage 3 is at the placing operation position. Then, when the stage 3 passes through the exposure area, exposure is performed, and when the stage reaches the recovery work position, the workpiece W is recovered from the stage 3. Since the mechanism is simple to perform such a simple operation, the apparatus cost can be reduced. In addition, the takt time is limited by the exposure in each exposure unit 1, and is not limited by the transport operation of the workpiece W. Therefore, a practical apparatus capable of performing the exposure process with high productivity can be provided.

In addition, if the position of the rewriting of the exposure pattern program 91 based on the imaging result of the imaging device 61 is shifted at the time when the imaging device 61 detects the workpiece W, the same shift is assumed when the workpiece W passes through the exposure area. In this case, although the offset (amount and direction) at the imaging position of the imaging element 61 and the offset when passing through the exposure region may be corrected as being completely the same, the offset may be corrected as a different offset having reproducibility. That is, the correlation when the displacement of the detection element 61 passes through the exposure region may be examined in advance, and the exposure pattern program may be rewritten in consideration of the correlation.

The same applies to the autofocus unit. In addition to the case where the projection optical system 13 is controlled by directly using the distance measured by the autofocus sensor 63, there may be a case where the control is performed such that the change in distance has reproducibility. That is, although there is a difference between the distance when passing under the autofocus sensor 63 and the distance when passing through the exposure area, if the different method has reproducibility, the difference may be examined in advance and the autofocus control signal may be generated in consideration of the difference.

In the above example, the main alignment is alignment (registration) of the irradiation position of the light of the exposure pattern, but the shape itself of the exposure pattern may be corrected. For example, when the shape of the workpiece W is slightly deformed, it is possible to perform exposure with an optimum exposure pattern in accordance with the deformation. The deformation of the workpiece W can be determined by capturing 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 result. In addition to the deformation, in the case where the size of the workpiece W is slightly different, it is also possible to correct the exposure pattern correspondingly thereto. The case where the size of the workpiece W is different from the reference value can be known by photographing a plurality of alignment marks and comparing the distance between the alignment marks and the reference value. Therefore, as a result, the exposure pattern rewriting program 62 may enlarge or reduce the exposure pattern and perform exposure in addition to the enlargement or reduction.

In fig. 1, only 1 autofocus sensor 63 is shown, but a plurality of autofocus sensors 63 are actually provided. Although the measurement results based on the distances measured by the respective autofocus sensors 63 may differ, in this case, the distance between the measurement points is calculated by performing an operation (for example, averaging) based on the measurement results.

In the above-described embodiment, the suction mechanism 7 for sucking the workpiece W is provided on the stage 3, and therefore, the positional deviation of the workpiece W can be prevented and exposure with high positional accuracy can be realized. That is, when the workpiece W is shifted after the alignment mark is imaged by the imaging element 61, the accuracy of the exposure position is directly affected, but in this embodiment, the workpiece W is attracted to the stage 3, and therefore, there is no such problem. Therefore, the suction of the work W is performed at least between the detection position of the alignment mark by the imaging element 61 and the exposure area. However, since alignment cannot be performed if a positional shift occurs after the pre-alignment and the alignment mark is out of the detectable range of the imaging element 61, it is more preferable to perform suction of the workpiece W between the work position of the pre-alignment and the exposure region.

Further, the suction of the workpiece W also has a meaning that exposure with high shape accuracy can be performed even when the workpiece W has a warp or the like. For example, when the workpiece W is a rigid printed circuit board, deformation such as a slight warp may occur. In this case, when the workpiece W is attracted with a sufficient force to the stage 3, the deformation is eliminated by the close contact with the stage 3, and the exposure can be performed in this state. Therefore, the exposure accuracy is not lowered regardless of the deformation. For this purpose, the work W may be adsorbed to the stage 3 at least when passing through the exposure region.

In addition, there are cases where no alignment mark is formed on the workpiece W, and there are cases where the imaging element 61 performs imaging of a portion other than the alignment mark. For example, the alignment mark may be a circuit pattern formed on the workpiece W and output a signal for alignment by imaging, or may be a circuit pattern formed on the workpiece W and output a signal for alignment by imaging the outline of the workpiece W itself.

In the above embodiment, the stage 3 is used as the workpiece mounting portion, but this is significant in that exposure accuracy is improved by providing a member having no flexibility. Since the workpiece placing unit is a member that optimizes the posture of the workpiece W during exposure, the workpiece W needs to be in a flat posture perpendicular to the optical axis of the exposure head when passing through the exposure region. Therefore, it is simple to use a member having no flexibility and to construct the turret mechanism 21 so as to be perpendicular to the optical axis during the turret rotation. That is, the stage 3, which is a member having no flexibility, is used as the workpiece placing section, and the structure for maintaining the posture of the workpiece W during exposure is simple.

A member having flexibility may be used as the workpiece mounting portion, and for example, a flexible tape may be used as the workpiece mounting portion. Steel belts such as stainless steel are commercially available, and are suitable for use because they cause less dust. Further, a resin conveyor belt such as a fluororesin may be used.

As the driving wheel 22 and the driven wheel 23 in the circling mechanism 21, a structure in which the workpiece placing section is revolved by friction force may be adopted in addition to the meshing of the meshing teeth as described above. In the case where the member having the above flexibility is used as a workpiece, the structure is particularly possible. Further, in some cases, a magnetic force may be used for transmission of the force between the driving portion and the workpiece mounting portion. That is, the driving wheel and the workpiece mounting portion may be magnetically coupled to each other, and the driving wheel may be rotated to rotate the workpiece mounting portion.

In addition, in order to have a flat posture perpendicular to the optical axis of the exposure head in the exposure region, it is preferable to perform tension adjustment in the turret mechanism 21. For example, when a flexible member as described above is used as the workpiece mounting portion, if the flexible member slacks when passing through the exposure region, the posture of the workpiece W changes, and the exposure accuracy decreases. Therefore, it is preferable to apply an appropriate tension to the workpiece mounting portion at least when passing through the exposure region. As a structure for this purpose, it is possible to apply an appropriate counter torque to the driven pulley 23. That is, when the driving wheel 22 rotates to pull the workpiece placement unit, a reverse torque is applied to the driven wheel 23, and the driving wheel 22 rotates against the torque.

The above-described structure is also effective in the case of a structure in which a work placing portion having no flexibility, such as the stage 3, is connected. In a structure in which members having no flexibility are joined, a backlash may exist in a joining portion. Due to the influence of the backlash, the workpiece mounting portion may be slightly inclined in the exposure region, and thus the exposure accuracy may be lowered. In order to prevent this, the driven pulley 23 may be similarly subjected to reverse torque, and the workpiece placement unit may be pulled from both sides.

In the operation of the direct type exposure apparatus, the turret mechanism 21 rotates each stage 3 at a constant speed, and the movement does not stop during the normal operation of the apparatus. However, a sequence that stops at an appropriate timing may be employed as necessary. For example, the stop may be easier when the workpiece W is prealigned and placed on the stage 3, and in this case, the operation of the turret mechanism 21 may be temporarily stopped. After the workpiece W is placed in the pre-aligned state, the operation of the turret mechanism 21 is started again. Further, the image pickup device 61 may be stopped when performing image pickup, and in this case, the movement may be temporarily stopped. When the movement is temporarily stopped in this manner, the workpiece W is not positioned in the exposure area at that time. This is because, if located in the exposure region, it is difficult to control the exposure time (light amount). Conversely, the structure in which the workpiece W does not stop has a meaning in which the control of the spatial light modulator 12 of the exposure unit 1 does not become complicated.

In the above embodiment, the structure of alignment may be changed as appropriate. For example, when the necessary positional accuracy is ensured only by the pre-alignment, the main alignment is not performed, and the imaging device 61 and the like are not provided.

In addition, the autofocus unit may not be necessary as long as the accuracy of the conveyance system 2 is sufficiently high. That is, depending on the relationship between the depth of focus of the projection optical system 13 and the necessary exposure contrast, if it is a mechanism in which the conveyance system 2 can convey the workpiece W sufficiently horizontally, the autofocus unit may not be necessary.

In addition, although a plurality of exposure units 1 are provided in the above embodiment, there may be a case where only one exposure unit 1 is provided. In the case of the exposure process on only one side, the inverting mechanism 81 is not provided, and another direct type exposure apparatus adjacent thereto is not provided.

The workpiece W may be a flexible sheet-like member other than a rigid plate-like member. Typically a flexible printed substrate.

Further, as an exposure process, exposure may be performed for the purpose of forming a circuit such as a printed circuit board, or for the purpose of forming a fine structure with a elaborate mechanism such as MEMS, and the direct type exposure apparatus having the above structure can be used for various applications.

Claims

1. A direct writing type exposure apparatus for exposing a plate-like or sheet-like workpiece by irradiating the workpiece with light having a predetermined pattern without a mask, comprising:

comprising:

an exposure head for irradiating the set exposure region with light of a predetermined pattern; and

a conveying system for conveying the workpiece through the exposure area,

the work conveying system has:

a revolving mechanism for revolving the workpiece placing part which is vertical and flat relative to the optical axis of the exposure head when passing through the exposure area along an annular revolving path;

a loader for placing an unexposed workpiece on a workpiece placing section; and

and an unloader for recovering the exposed workpiece from the workpiece placing section.

2. The direct writing exposure apparatus according to claim 1,

an alignment sensor is provided at a position for detecting a state of the workpiece on the loop path between a mounting position at which the unexposed workpiece is mounted on the loader and the exposure area,

and an alignment unit that corrects an irradiation position of the light based on the prescribed pattern of the exposure head based on a signal from an alignment sensor.

3. The direct writing exposure apparatus according to claim 2,

The alignment means is a means for correcting the irradiation position by using a signal from the alignment sensor that detects the state of the workpiece moving on the circulating path.

4. The direct writing exposure apparatus according to any one of claims 1 to 3,

the exposure head includes a projection optical system that forms the light of the prescribed pattern,

an autofocus sensor for measuring a distance to the workpiece placed on the workpiece placing section is provided on the loop path between the placing work position and the exposure area,

and is provided with an auto-focusing unit that controls the projection optical system in accordance with a measurement result measured by the sensor for auto-focusing.

5. The direct writing exposure apparatus according to claim 4,

the autofocus unit is a unit that controls the projection optical system based on a signal from the autofocus sensor that measures the distance to the workpiece moving on the loop.

6. The direct writing exposure apparatus according to claim 1,

the work-piece suction device is provided with a suction mechanism which sucks the work-piece on the work-piece placing part at least when the work-piece placed on the work-piece placing part passes through the exposure area.

7. The direct writing exposure apparatus according to claim 2 or 3,

the work mounting apparatus includes an adsorption mechanism for adsorbing the work, which has been detected by the alignment sensor, onto the work mounting portion at least from the time of the detection until the work passes through the exposure area.