TWI856074B - Direct drawing exposure device - Google Patents

Abstract

[Topic] Provide a direct-drawing exposure device with a simple structure, low cost and high productivity for performing exposure processes. [Solution] Connect a plurality of workpiece mounting parts, namely platforms (3), and rotate along an endless rotation path by a rotating mechanism (21). The loader (4) mounts an unexposed workpiece (W) on the platform (3) that has reached the mounting position, and by the movement of the platform (3), when the workpiece (W) passes through the exposure area, the exposure head (1) irradiates the light of the exposure pattern to the exposure area to expose the workpiece (W). The workpiece (W) is adsorbed on the platform (3) by an adsorption mechanism (7), and the irradiation position of the exposure pattern is corrected by an alignment means. The exposed workpiece (W) is recovered by the unloader (5).

Description

Direct drawing exposure device

The invention of the application is related to a direct drawing exposure device, which performs exposure by irradiating a predetermined pattern of light onto a workpiece without using a mask. Hereinafter, the predetermined pattern of light during exposure is referred to as an exposure pattern.

Exposure technology, which is a main technology of photolithography, is used actively in the formation of various fine circuits or fine structures, etc., by exposing an object having a photosensitive layer formed on its surface and sensitizing the photosensitive layer. A representative exposure technology is as follows: light is irradiated to a mask having the same pattern as the exposure pattern, and the image of the mask is projected onto the surface of the object, whereby the light of the exposure pattern is irradiated to the object.

Different from the exposure technology using such a mask, the following technology is known: using a spatial light modulator to directly form an image on the surface of the object for exposure. Hereinafter, in this specification, this technology will be referred to as direct drawing exposure. In direct drawing exposure, a typical spatial light modulator is DMD (Digital Mirror Device). DMD has a structure in which tiny square mirrors are arranged in a right-angle grid. Each mirror is independently controlled at an angle relative to the optical axis, and can take a posture of reflecting the light from the light source to reach the object or a posture of not allowing the light from the light source to reach the object. DMD has a controller for controlling each mirror, and the controller controls each mirror according to the exposure pattern so that the light of the exposure pattern is irradiated to the surface of the object.

In the case of direct-drawing exposure, since no mask is used, it can be advantageous in the production of a large number of varieties and in small quantities. In the case of exposure using a mask, a mask must be prepared for each variety, and the cost of storing the mask is also high. In addition, when replacing the mask in order to produce a different variety, the operation of the device must be stopped and restarted, which requires manpower and time. Therefore, it becomes a factor in the decrease in productivity. On the other hand, in the case of direct-drawing exposure, it is only necessary to prepare the control program of each lens for each variety, and when manufacturing different varieties, it can be handled by simply changing the control program. Therefore, the advantages in cost and productivity are obvious. In addition, the exposure pattern can be fine-tuned for the workpiece (exposure object) as needed, which also provides excellent process flexibility.

In such a direct drawing exposure device, a platform on which the workpiece is placed is used in order to set the workpiece in a position perpendicular to the optical axis of the exposure unit with a built-in spatial light modulator. The exposure unit can irradiate the set area (hereinafter referred to as the exposure area) with light of an exposure pattern, and the platform on which the workpiece is placed is moved through the exposure area by a conveying system, and the workpiece is exposed while passing through the exposure area.

In direct-drawing exposure devices such as this, a dual-stage structure with two platforms is often used to improve productivity. The structure disclosed in Patent Document 1 is also an example. In the dual-stage structure, the platforms are arranged on both sides of the exposure area, and each platform carrying the workpiece alternately passes through the exposure area to perform exposure. In this case, a loading (loading)/unloading (recovery) mechanism is provided on one side of the exposure area, and a loading/unloading mechanism is also provided on the other side. [Prior technical document] [Patent document]

[Patent Document 1] Japanese Patent Application Publication No. 2008-191303

[Problems to be solved by the present invention]

In the above-mentioned direct drawing exposure device, it is frequently required to expose both sides of the workpiece. When exposing both sides, two direct drawing exposure devices are arranged vertically, and after the first device exposes one side, the second device also exposes the other side. A reversing mechanism for flipping the workpiece is arranged between the first device and the second device. In this way, when two direct drawing exposure devices are arranged vertically, the structure of the double stage 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 reverses the front and back of the workpiece and then transfers it to the loading mechanism of the second direct-drawing exposure device.

Since the two platforms are only used to load the workpieces on one side, they are moved alternately to the loading position. The platform on which the workpiece is loaded at the loading position moves to the other side through the exposure area for exposure, and after the workpiece is unloaded, returns to one side to load the workpiece again. The two platforms are configured as opposing cantilever structures in a manner that does not interfere with each other. That is, the platform on one side is held in the conveying direction by an arm body extending from the left side, for example, and the platform on the other side is held by an arm body extending from the right side. The arm bodies are respectively connected to lifting mechanisms, and when one platform moves along the conveying line, it is configured to retreat to the top or bottom without interfering with each other.

As mentioned above, the direct drawing exposure device with a dual stage equipped with two platforms has a significantly improved productivity compared to the device equipped with only one platform. However, the structure is easy to become complicated and large-scale, and the cost is easy to increase. This problem becomes significant when one side is configured as a loading side and the other side is configured as a unloading side. In addition, until the retreat action of one platform is completed, the other platform cannot be performed on the transport line, so there may be a situation where the takt time is limited in this part. In this way, the advantage of the dual stage is hindered and the productivity cannot be significantly improved.

The invention of this application is the result of a study to solve the problem of productivity of such a direct drawing exposure device, and the purpose is to provide a direct drawing exposure device with a simple structure and low cost and capable of performing an exposure process with high productivity. [Means for solving the problem]

In order to solve the above-mentioned problem, the direct drawing exposure device of the application is to expose a plate-shaped or thin sheet-shaped workpiece by irradiating light of a predetermined pattern without using a mask. The direct drawing exposure device is characterized by having: an exposure head, which irradiates light of a predetermined pattern to a set exposure area; and a conveying system, which conveys the workpiece through the exposure area. The workpiece conveying system is equipped with: a rotating mechanism, which rotates a workpiece mounting portion which is perpendicular to the optical axis of the exposure head and in a flat posture along an endless rotation path when passing through the exposure area; a loader, which places unexposed workpieces on the workpiece mounting portion; and an unloader, which recovers the exposed workpieces from the workpiece mounting portion. Furthermore, in order to solve the above-mentioned problem, the direct drawing exposure device may have the following structure: an alignment sensor is provided at the position of "detecting the state of the workpiece on the rotating path between the loading position of the unexposed workpiece on the loader and the exposure area", and an alignment means is provided, and the alignment means corrects the irradiation position of the light of the predetermined pattern performed by the exposure head by the signal from the alignment sensor. In order to solve the above-mentioned problem, the alignment means may be a means of "correcting the irradiation position by the signal from the alignment sensor that detects the state of the moving workpiece on the rotating path". Furthermore, in order to solve the above-mentioned problem, the direct drawing exposure device may have the following structure: the exposure head includes a projection optical system for forming an exposure pattern, and an autofocus sensor for "measuring the distance to the workpiece placed on the workpiece placement portion" is provided on the rotation path between the loading operation position and the exposure area, and an autofocus means for "controlling the projection optical system according to the measurement result of the autofocus sensor" is provided. Furthermore, in order to solve the above-mentioned problem, the autofocus means may be a means for "controlling the projection optical system according to the signal from the autofocus sensor for measuring the distance to the moving workpiece on the rotation path". Furthermore, in order to solve the above-mentioned problem, the direct-drawing exposure device may be provided with: an adsorption mechanism that adsorbs the workpiece placed on the workpiece mounting portion to the workpiece mounting portion at least when the workpiece passes through the exposure area. Furthermore, in order to solve the above-mentioned problem, the direct-drawing exposure device may be provided with: an adsorption mechanism that adsorbs the workpiece whose state is detected by the alignment sensor to the workpiece mounting portion at least from the time point of the detection until the workpiece passes through the exposure area. [Effect of the invention]

As described below, the direct drawing exposure device according to the application has a simple structure that performs simple actions such as "when the platform rotating along the endless rotation path is at the loading operation position, the workpiece is loaded onto the platform, and when the platform passes through the exposure area, the workpiece is exposed, and then, when it reaches the recovery operation position, the workpiece is recovered from the platform." Therefore, the device cost can be reduced. In addition, the exposure of the exposure unit is what limits the production time, and it is not limited by the transport action of the workpiece. Therefore, a practical device that can perform an exposure process with high productivity can be provided. Furthermore, when the state of the workpiece is detected on the rotating path between the loading position and the exposure area, and the exposure pattern irradiation position is corrected accordingly, even if the workpiece is misaligned and arranged on the workpiece loading portion, the light of the exposure pattern is irradiated to the correct position. Therefore, exposure with higher position accuracy can be performed. Furthermore, when the alignment means is a means of "correcting the exposure pattern irradiation position by a signal from an alignment sensor that detects the state of the moving workpiece on the rotating path", it is not necessary to stop the movement of the rotating mechanism in order to detect the state of the workpiece, and the control of the exposure unit is not complicated. Furthermore, in the configuration of "the autofocus sensor measures the distance to the workpiece on the rotation path between the loading position and the exposure area, and the projection optical system is autofocused based on the result", a more vivid exposure pattern is irradiated on the workpiece, so that exposure with higher accuracy can be performed. At this time, in the configuration of "the autofocus sensor measures the distance to the moving workpiece on the rotation path", it is not necessary to stop the operation of the rotation mechanism in order to measure the distance, and the control of the exposure unit is not complicated. Furthermore, in the configuration of "at least when passing through the exposure area, the workpiece mounted on the workpiece mounting portion is adsorbed on the workpiece mounting portion", even if the workpiece is deformed such as warping, exposure is performed in a state where the deformation is eliminated. Therefore, a more accurate exposure process can be performed. In addition, in the configuration of "the workpiece is adsorbed on the workpiece mounting portion from the time when the state is detected by the alignment sensor until it passes through the exposure area", the accuracy of the irradiation position of the exposure pattern will not decrease due to the position deviation during transportation. Therefore, in this regard, a more accurate exposure process can be performed.

Next, the form for implementing the invention of the application (hereinafter, the implementation form) is described. Figures 1 and 2 are schematic diagrams of a direct-drawing exposure device of the implementation form, Figure 1 is a front schematic diagram, and Figure 2 is a plane schematic diagram. The direct-drawing exposure device shown in Figures 1 and 2 comprises: an exposure unit 1 for irradiating an exposure area with light of an exposure pattern; and a conveying system 2 for conveying a workpiece W through the exposure area. In the implementation form, the workpiece W is formed into a plate shape. More specifically, in the implementation form, the direct-drawing exposure device is a device for manufacturing printed circuit boards, and therefore, the workpiece W is a substrate for printed circuit boards. Regarding printed circuit boards, although thin sheet-shaped soft substrates are also known, in the implementation form, a rigid substrate is formed of a resin such as polyimide.

Fig. 3 is a schematic diagram of an exposure unit 1 in a direct drawing exposure device of an embodiment. As shown in Fig. 3, the exposure unit 1 comprises: a light source 11; a spatial light modulator 12 for spatially modulating the light from the light source 11; and an optical system (hereinafter, a projection optical system) 13 for projecting an image formed by 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 the optimal wavelength according to the sensitive wavelength of the photosensitive layer in the workpiece W. The sensitive wavelength of the photoresist film is mostly from the visible short wavelength region to the ultraviolet region. As the light source 11, a light source that outputs light from the visible short wavelength region such as 405nm or 365nm to the ultraviolet region is used. In addition, in order to bring out the performance of the spatial light modulator 12, it is better to output coherent light, so it is suitable to use a laser light source. For example, a semiconductor laser of the gallium nitride (GaN) system is used.

In this embodiment, a DMD is used as the spatial light modulator 12. As mentioned above, in the DMD, each pixel is a tiny mirror (not shown in FIG. 2 ). The mirror (hereinafter referred to as a pixel mirror) is, for example, a square mirror with an angle of 13.68 μm, and is configured such that a plurality of pixel mirrors are arranged in a right-angle grid. The number of the arrays is, for example, 1024×768.

The spatial light modulator 12 is provided with a modulator controller 121 for controlling each pixel mirror. The direct drawing exposure device of the embodiment is provided with a main control unit 9 for controlling the whole. The modulator controller 121 controls each pixel mirror according to the signal from the main control unit 9. In addition, each pixel mirror takes the plane on which each pixel mirror is arranged as the reference plane, and can take a first posture along the reference plane and a second posture inclined relative to the reference plane by, for example, 11 to 13 degrees. In the embodiment, the first posture is the OFF state, and the second posture is the ON state. The spatial light modulator 12 includes a driving mechanism for driving each pixel mirror, and the modulator controller 121 can independently control each pixel mirror to take the first posture or the second posture. A spatial light modulator 12 such as this one is available from Texas Instruments.

As shown in FIG3 , the exposure unit 1 has an irradiation optical system 14 for irradiating the spatial light modulator 12 with light from the light source 11. In this embodiment, the irradiation optical system 14 includes an optical fiber 141. In order to form an image with a higher illumination, one exposure unit 1 has 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-based multimode optical fiber is used.

In order to form an image with good precision using the DMD, i.e., the spatial light modulator 12, it is more ideal to make parallel light incident and reflect it at each pixel mirror, and it is more ideal to make the light incident obliquely relative to each pixel mirror. Therefore, the illumination optical system 14 is as shown in FIG3, and has: a collimator lens 142, which makes the light emitted from each optical fiber 61 and diffused into parallel light; and a reflector 143, which makes the light incident obliquely to the spatial light modulator 12. "Oblique" refers to the inclination relative to the reference plane of the spatial light modulator 12. In terms of the incident angle relative to the reference plane, it is set to an angle of about 22 to 26 degrees, for example.

The projection optical system 13 is composed of two projection lens groups 131, 132 and a micro lens array (hereinafter referred to as MLA) 133 arranged between the projection lens groups 131, 132. The MLA 133 is arranged auxiliaryly for performing exposure with higher shape accuracy. The MLA 133 is an optical component that arranges a large number of micro lenses in a right-angle grid shape. Each lens element corresponds to each pixel lens of the spatial light modulator 12 on a one-to-one basis.

In the above-mentioned exposure unit 1, the light from the light source 11 is guided by the optical fiber 141 and then incident on 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 and is set to a posture that is selectively tilted according to the exposure pattern to be formed. That is, according to the exposure pattern to be formed, the pixel mirror located at the position where the light is to reach the exposure area is set to the second posture (ON state), and the pixel mirrors other than it are set to the first posture (OFF state). The light reflected to the pixel mirror in the OFF state will not reach the exposure area, and only the light reflected to the pixel mirror in the ON state will reach it. Therefore, the light of the predetermined exposure pattern is irradiated to the exposure area.

The control signal is sent from the main control unit 9 to each modulator controller 121 to achieve a predetermined exposure pattern. The control signal is a sequence for driving each pixel lens. In the main control unit 9, in order to achieve a predetermined exposure pattern, a program 91 including each sequence sent to each modulator controller 121 is stored in the memory unit 900 of the main control unit 9. Hereinafter, this program is referred to as the exposure pattern program 91. The exposure pattern program 91 is prepared in advance based on design information such as what kind of circuit is formed in the work W, and is stored in the memory unit 900 of the main control unit 9.

There are multiple exposure heads 1 like this. As shown in FIG2, in this embodiment, 8 exposure heads 1 are provided. The 8 exposure heads 1 form an exposure pattern as a whole. In addition, each exposure head 1 has the same structure. Refer to FIG4 for additional explanation about the exposure area. FIG4 is a three-dimensional schematic diagram of the exposure area. In FIG4, the area (hereinafter referred to as the individual area) E that can be irradiated with light by one exposure head 1 is represented by a square frame. The collection of individual areas E is the exposure area.

The workpiece W receives light irradiation in each individual area E while moving in the direction indicated by the arrow in FIG4 (transportation direction). At this time, since the two rows of exposure heads 1 are staggered, exposure can be performed without gaps even in the horizontal direction perpendicular to the transport direction. In fact, each individual area E is a collection of tiny irradiation patterns (hereinafter referred to as tiny patterns). A tiny pattern is a pattern formed by a pixel lens 31. Although the workpiece W carried by the platform 3 moves in the exposure area along with the movement of the platform 3, the tiny pattern is turned on and off in a predetermined order in accordance with the timing of its movement. In this way, the desired exposure pattern is formed on the workpiece W.

Next, the conveying system 2 is described. The main feature of the direct-drawing exposure device of this embodiment is that a rotating mechanism 21 is used to rotate a component (workpiece mounting portion) carrying a workpiece W along a non-end-shaped rotating path. Specifically, in this embodiment, the workpiece mounting portion is a platform 3. The platform 3 is a low-height trapezoidal component. The rotating mechanism 21 is a mechanism that rotates the platform 3 in a vertical plane as shown in FIG. 1.

FIG. 5 is a three-dimensional schematic diagram of the rotating mechanism 21 provided in the conveying system 2. FIG. 6 is a three-dimensional schematic diagram showing the connection structure of each platform. In the following description, the travel direction of each platform 3 in the rotating path is set to the front-rear direction, and the horizontal direction perpendicular thereto is set to the left-right direction. As shown in FIG. 1 and FIG. 5, a plurality of platforms 3 are arranged side by side along the endless rotating path. Although the illustration is omitted in FIG. 5, as shown in FIG. 6, each platform 3 is connected to each other by a connector 31. Each platform 3 has a connecting portion 32 at the front and rear. Each connecting portion 32 is a portion extending from the platform 3 to the front and rear. The connecting portion 32 is arranged on the left and right, and a total of 4 are arranged. In this embodiment, the connector 31 is a connecting pin. Each connecting portion 32 is formed with a pin insertion hole, and each platform 3 is connected by inserting a connecting pin into the pin insertion hole. In each platform 3, there is a pair of connecting portions 32 on the rear side and a single connecting portion 32 on the front side. Each platform 3 is connected by a connecting device 31 in which the connecting portion 32 on the front side is inserted between the connecting portions 32 on the rear side of the front platform 3.

As shown in FIG5 , the rotating mechanism 21 has: a pair of driving wheels 22; and a pair of driven wheels 23. The pair of driving wheels 22 are arranged at the front side of the rotating path. The pair of driving wheels 22 are fixed to a driving shaft 221 extending to the left and right, and a driving source not shown is connected to the driving shaft 221. The pair of driven wheels 23 are arranged at the rear side of the rotating path. The pair of driven wheels 23 are fixed or connected to a driven shaft 231 extending to the left and right.

Each platform 3 is formed with a plurality of engagement holes 34 on the side in the left-right direction. As shown in FIG5 , each driving wheel 22 and each driven wheel 23 are gear-shaped and have engagement teeth. Each engagement hole 34 is formed into a shape that matches the size of each engagement tooth. When a pair of driving wheels 22 are driven to rotate by a driving source not shown in the figure, each engagement tooth sequentially engages with each engagement hole 34, and each connected platform 3 moves along the rotation path. At this time, each engagement tooth of the driven wheel 23 also sequentially engages with each engagement hole 34 while being driven. In this way, each platform 3 rotates along the rotation path.

1 and 2, a loader 4 is provided behind the rotary mechanism 21, and an unloader 5 is provided in front of the rotary 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 in-carrying conveyor 40 is located at the place where the loader 4 is installed. The loader 4 is equipped with: an in-carrying arm 42 having a suction plate 41; and an in-carrying side arm driving mechanism 43, which moves the in-carrying arm 42 up and down and forward and backward and left and right. A plurality of suction plates 41 are arranged in a downward-facing posture, and can hold the workpiece W by vacuum suction. The out-carrying conveyor 50 for sending the workpiece W to the next process is located at the place where the unloader 5 is installed. The unloader 5 is also equipped with: an out-carrying arm 52 having a suction plate 51; and an out-carrying side arm driving mechanism 53, which moves the out-carrying arm 52 up and down and forward and backward and left and right, similar to the loader 4.

As can be seen from the above description, although each platform 3 is rotated by the rotating mechanism 21, the workpiece W is placed on the platform 3 and moves in the upper part of the peripheral path shown in FIG. 1. During this period, the workpiece W passes through the exposure area and is exposed. Hereinafter, the upper part of the rotating path is referred to as the main transport path. In addition, the position where the loader 4 performs the loading action of the workpiece W is referred to as the loading operation position, and the position where the unloader 5 performs the recovery action of the workpiece W is referred to as the recovery operation position.

In addition, the speed of the rotation movement of each stage 3 by the rotation mechanism 21 refers to the speed limited by the exposure performed by each exposure unit 1. That is, as mentioned above, although each exposure pattern program 91 is installed for each exposure unit 1, the ON and OFF sequence of each pixel lens here is based on the premise that the workpiece W moves at a fixed speed. Moreover, the speed is preset in relation to the required exposure amount, and each exposure pattern program 91 is programmed based on this. In addition, a control signal is sent to the rotation mechanism 21 so that it rotates at a fixed speed.

A direct drawing exposure device of such an implementation form is provided with means for improving the pattern accuracy of the exposure process. Specifically, it is provided with: an alignment means for correcting the exposure pattern in response to the state of the workpiece W when it is transported to the exposure area; and an autofocus means for controlling the projection optical system 13 to make the exposure pattern clear. First, the alignment means are explained. As alignment means, there are pre-alignment means and formal alignment means. The pre-alignment means is a means for adjusting the loading position of the workpiece W for formal alignment. The formal alignment means is a means for correcting the exposure pattern in response to the state of the workpiece W.

As shown in Fig. 1, an alignment sensor is provided on the main conveying path. In this embodiment, the alignment sensor is an imaging element 61. A plurality of positioning marks are provided on the workpiece W, and an imaging element 61 is provided at a position for photographing each positioning mark.

In this embodiment, the pre-alignment means is a means for mechanically performing alignment. The purpose of pre-alignment is to make each positioning mark enter the field of view (photographable range) of the imaging element 61 when the workpiece W is transported along the main transport path. Although omitted in the figure, the pre-alignment means includes an abutment plate fixed at a predetermined position in a predetermined posture. The abutment plate is, for example, a component in the form of a 90-degree strip, and is configured with the width direction as a vertical direction. Pre-alignment is performed using the carry-in arm 42. That is, the carry-in arm 42 abuts against the abutment plate when holding the workpiece W, and in its state, holds the workpiece W again in a predetermined position relationship. In this way, pre-alignment is performed.

In addition, as shown in FIG1 , the imaging element 61 is located above the main transport path. This position refers to the position where the positioning mark of the workpiece W moving on the main transport path enters the field of view. In other words, when moving on the main transport path, the workpiece W is pre-aligned by the pre-alignment means in such a way that the positioning mark enters the field of view of the imaging element 61.

Formal alignment is to determine the state of the workpiece W from the imaging element 61, and to change the exposure pattern accordingly. "The state of the workpiece W" includes the position of the workpiece W relative to each exposure unit 1. That is, when the workpiece W passes through the exposure area, the formation position of the exposure pattern (the irradiation position of the light of the exposure pattern) is changed according to its position. In other words, the data from the imaging element 61 is used to determine how much the position of the workpiece W when passing through the exposure area deviates from the reference position and in which direction, and the formation position of the exposure pattern is changed accordingly. Changing the formation position of the exposure pattern is carried out in the form of changing (rewriting) the exposure pattern program 91. The formal alignment means includes an exposure pattern rewriting program 62, which is installed in the main control unit 9. The exposure pattern rewriting program 62 is programmed in such a way that "the data from each imaging element 61 is processed to calculate the formation position of the exposure pattern, and the exposure pattern program 91 is rewritten based on the result". In addition, since the imaging element 61 takes a picture of the positioning mark of the workpiece W moving on the main conveying path, in fact, the data of the appropriate still picture is extracted from the moving picture data and processed, thereby obtaining the deviation of the position of the workpiece W from the reference position.

An exposure sequence program 90 for operating each part of the device in a predetermined sequence is installed in the main control unit 9. The exposure pattern rewriting program 62 is read from the exposure sequence program 90 and executed every time a signal is output from each imaging element 61.

Next, the autofocus means will be described. The autofocus means comprises: an autofocus sensor 63; and an autofocus program 64, which generates a control signal for the projection optical system 3 in response to a signal from the autofocus sensor 63. The autofocus means is a means for "controlling the projection optical system 13 in response 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 rangefinder arranged on the main transport path on the front side of the exposure area. A laser rangefinder using laser interferometry is used as the autofocus sensor 63. The auto focus sensor 63 is arranged above the main transport path, and measures the distance to the workpiece W at a position slightly ahead of the exposure area.

The main control unit 9 is provided with an autofocus program 64, which determines the arrangement positions of the projection lens groups 131 and 132 in accordance with the focal distances of the projection lens groups 131 and 132 included in the projection optical system 13 and the signal from the autofocus sensor 63. The autofocus program 64 is executed by being read by the exposure sequence program 90 each time the signal from the autofocus sensor 63 is input to the main control unit 9. The execution result of the autofocus program 64 is the data of the arrangement positions of the projection lens groups 131 and 132, and the exposure sequence program 90 sends this as a control signal to the projection optical system 13. The projection optical system 13 includes a driving mechanism (not shown) for changing the arrangement position of each projection lens group 131, 132, and changes the arrangement position of each projection lens group 131, 132 according to the control signal sent.

A direct-drawing exposure device of such an embodiment is provided with: an adsorption mechanism 7, which adsorbs the workpiece W to the workpiece loading portion at least when the workpiece W passes through the exposure area. The adsorption mechanism 7 is provided with: an adsorption box 71; and an exhaust system 72, which exhausts the adsorption box 71. FIG. 7 is a side sectional schematic diagram showing the adsorption of the workpiece W by the adsorption mechanism 7. That is, FIG. 7 is a sectional schematic diagram in the left-right direction. As shown in FIG. 1, the adsorption box 71 is arranged in the rotary path and is located at the lower side of the main conveying path. The length of the adsorption box 71 is a length slightly longer than the length between the loading operation position and the exposure area position.

Each adsorption platform 3 has: a plurality of vacuum adsorption holes 30. As shown in FIG7 , the adsorption box 71 is open on the upper side and forms a space that is almost closed on the lower side of the adsorption platform 3 located on the main conveying path. The adsorption box 71 is connected to an exhaust source such as an exhaust blower or an exhaust pump through an exhaust pipe. When the exhaust source is in operation, the adsorption box 71 becomes negative pressure (vacuum). Therefore, the workpiece W on the platform 3 located on the upper side is adsorbed on the platform 3. In order for each platform 3 to move on the main conveying path, a gap C is formed between the upper end of the adsorption box 71 and the bottom of each platform 3. The gap C is preferably set to about 1~5mm. If it is larger than 5 mm, sufficient negative pressure cannot be obtained and the adsorption of the workpiece W becomes insufficient. If it is smaller than 1 mm, the rotation mechanism 21 is required to have extremely high precision, which results in an unnecessary and expensive mechanism.

In addition, the direct drawing exposure device of this embodiment is used in a process of exposing both sides of the workpiece W, and the next process is to expose the opposite side. Therefore, as shown in FIG. 1, an inverting machine 81 is provided adjacent to the unloading conveyor 50. The inverting machine 81 is a mechanism for holding the workpiece W up and down and reversing it up and down. In front of the inverting mechanism 81, another direct drawing exposure device having the same structure is provided.

Although such a direct drawing exposure device is assumed to be installed in a clean room, in this embodiment, it is particularly installed together with a clean test bench 82. The clean test bench 82 is a mechanism that is arranged above the device and allows clean air to flow downward. In this regard, the conveying system 2 includes a mechanical driving part or connecting part such as a driving wheel 22 or a driven wheel 23, and it is considered that dust is easily generated. Since the part that is easy to generate dust is located below the workpiece W being transported, dust will not adhere to the workpiece W due to the flow from above.

Next, the operation of the direct drawing exposure device of the embodiment will be described. In the direct drawing exposure device of the embodiment, when the device is in operation, the rotating mechanism 21 rotates each platform 3 at a constant speed. The constant speed here is a speed limited by the relationship between each exposure performed by each exposure unit 1 as described above. When the workpiece W is transported to the loading operation position by the conveyor 40, the loader 4 loads the workpiece W on the platform 3. At this time, the pre-alignment means is activated to pre-align the workpiece W. Therefore, it is loaded on the platform 3 in the pre-aligned state. In addition, as shown in Figure 1, in this embodiment, the length of the workpiece W in the conveying direction is shorter than the length of the platform 3 in the same direction. Therefore, the workpiece W is loaded across a plurality of platforms 3 in the front and rear.

The workpiece W placed on the platform 3 is transported along the main transport path by the movement of the platform 3 by the rotating mechanism 21. Moreover, when passing under the imaging element 61, the positioning mark is photographed by the imaging element 61. Moreover, when passing under the autofocus sensor 63, the autofocus sensor 63 measures the distance to the workpiece W. Moreover, the output of the imaging element 61 is input to the main control unit 9 to execute the exposure pattern rewriting program 62 to rewrite each exposure pattern program 91. Moreover, the output of the autofocus sensor 63 is also input to the main control unit 9, and the control signal is sent to each projection optical system 13 to adjust the configuration 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 the workpiece W is exposed with a predetermined exposure pattern when passing through the exposure area. Then, the rotating mechanism 21 continuously moves at a constant speed. When the workpiece W exceeds the exposure area and reaches the recovery operation position, the unloader 5 moves at its timing and recovers the workpiece W from the unloading platform 3 and transfers it to the unloading conveyor 50. In addition, the unloading conveyor 50 carries the workpiece W out to the reversing mechanism 81, which turns the workpiece W over and holds it again, and sends it to another adjacent direct drawing exposure device not shown in the figure for exposure of the back surface.

On the other hand, the next workpiece W is carried into the carrying conveyor 40, and the same action is repeated in parallel. That is, it is placed on the platform 3 after pre-alignment, photographed by the imaging element 61 moving on the main conveying path, and measured by the sensor for autofocus 63, and exposed when passing through the exposure area. In this way, the rotating mechanism 21 rotates a series of platforms 3 at a constant speed, and the loader 4 loads the workpieces W one by one, and each workpiece W passes through the exposure area and is exposed to light in turn.

In the direct drawing exposure device of the embodiment, as described above, the platform 3 rotates along the endless rotation path, and when the platform 3 is located at the loading operation position, the workpiece W is loaded onto the platform 3. Moreover, the exposure is performed when the platform 3 passes through the exposure area, and then, when the workpiece W reaches the recovery operation position, the workpiece W is recovered from the platform 3. Since it is a simple mechanism that performs such a simple operation, the cost of the device can be reduced. In addition, the production time is limited by the exposure of each exposure unit 1, and is not limited by the conveying operation of the workpiece W. Therefore, a practical device that can perform an exposure process with high productivity can be provided.

In addition, the rewriting of the exposure pattern program 91 based on the shooting result of the imaging element 61 is based on the premise that "as long as the imaging element 61 deviates from the position at the time when the workpiece W is detected, the same deviation will occur when passing through the exposure area." In this case, although there is a situation where the deviation (amount and direction) of the imaging position performed by the imaging element 61 is assumed to be the same as the deviation when passing through the exposure area and correction is performed, there is also a situation where the correction is performed assuming different deviations with reproducibility. That is, there is also a situation where the correlation of the deviation caused by the detection element 61 when passing through the exposure area is pre-investigated, and the exposure pattern program is rewritten in consideration of this. The above point is also the same for the autofocus means. In addition to directly using the distance measured by the autofocus sensor 63 to control the projection optical system 13, there may be a case where the change in distance is reproducible and control is performed. 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, as long as the method of the difference is reproducible, there may be a case where this is investigated in advance and the control signal for autofocus is generated in consideration of this.

In the above example, although formal alignment refers to the alignment (positioning) of the exposure pattern's light irradiation position, there may also be a situation where the shape of the exposure pattern itself is corrected. For example, when the shape of the workpiece W is slightly deformed, there may also be a situation where the exposure is performed with the best exposure pattern to match the deformation. The deformation of the workpiece W can be judged by photographing a plurality of positioning marks and processing their image data, and the exposure pattern rewriting program 62 rewrites the exposure pattern program 91 according to the result. In addition to deformation, when the size of the workpiece W is slightly different, there may also be a situation where the exposure pattern is corrected accordingly. The size of the workpiece W is different from the reference value, which can be known by photographing a plurality of positioning marks and comparing the distance between the two with the reference value. Therefore, there may be a case where the exposure pattern rewriting program 62 enlarges or reduces the exposure pattern based on the result and performs exposure on it. In addition, although only one autofocus sensor 63 is shown in FIG1 , in fact, a plurality of autofocus sensors 63 are provided. Although there may be a case where the distance measurement results performed by each autofocus sensor 63 are different, in that case, the distance between the measurement points is calculated from the measurement results by calculation (for example, obtaining an average).

In addition, in the above-mentioned embodiment, the adsorption mechanism 7 for adsorbing the workpiece W to the platform 3 is provided, the purpose of which is to prevent the position deviation of the workpiece W and to perform exposure with high position accuracy. That is, after the imaging element 61 photographs the positioning mark, when the workpiece W deviates, although it directly leads to a decrease in the accuracy of the exposure position, in this embodiment, since the workpiece W is adsorbed to the platform 3, there is no such problem. Therefore, it is sufficient to adsorb the workpiece W at least between the detection position of the positioning mark of the imaging element 61 and the exposure area. However, after pre-alignment, when a position deviation occurs and causes the positioning mark to deviate from the detectable range of the imaging element 61, it is impossible to perform pre-alignment. Therefore, it is better to adsorb the workpiece W between the pre-aligned working position and the exposure area.

Furthermore, the adsorption of the workpiece W is also significant in that even when the workpiece W has warps, etc., exposure with high shape accuracy can be performed. For example, when the workpiece W is a rigid printed substrate, there is a possibility that slight warps, etc., may occur. In this case, when the workpiece W is adsorbed on the platform 3 with sufficient force, the deformation can be eliminated by close contact with the platform 3, and exposure can be performed in this state. Therefore, regardless of the deformation, the exposure accuracy will not be reduced. The purpose is that it is sufficient for the workpiece W to be adsorbed on the platform 3 at least when passing through the exposure area.

In addition, there may be a case where the positioning mark is not formed on the workpiece W, and there may be a case where the imaging element 61 captures something other than the positioning mark. For example, there may be a case where a circuit pattern on which the positioning mark is formed on the workpiece W is captured and a signal for alignment is output, or there may be a case where the outline of the workpiece W itself is captured and a signal for alignment is output.

In the above-mentioned embodiment, although the platform 3 is used as the workpiece mounting part, the significance of this point is to improve the exposure accuracy by setting it as an inflexible component. Since the workpiece mounting part is a component that makes the posture of the workpiece W the best during exposure, the workpiece W must be in a vertical and flat posture with respect to the optical axis of the exposure head when passing through the exposure area. For this reason, it is simpler to "use an inflexible component and construct the rotating mechanism 21 in a manner that is vertical to the optical axis during rotation." That is, the significance of using the inflexible component, i.e., the platform 3, as the workpiece mounting part is to simplify the structure in order to maintain the posture of the workpiece W during exposure.

It is also possible to use a flexible member and workpiece mounting portion, and for example, a flexible conveyor belt as a workpiece mounting portion. Since conveyor belts made of steel such as stainless steel are available on the market and generate less dust, they can be used appropriately. In addition, conveyor belts made of resin such as fluorine resin can also be used.

As for the structure of the driving wheel 22 or the driven wheel 23 in the rotating mechanism 21, in addition to the meshing of the meshing teeth as described above, it is also possible to use a structure that rotates the workpiece mounting part by friction. This is a structure that can exist specifically when the above-mentioned flexible component becomes a workpiece. Moreover, regarding the transmission of force between the driving part and the workpiece mounting part, there may also be a situation where magnetic force is used. That is, it is also possible to adopt a structure of "coupling the driving wheel and the workpiece mounting part by magnetic force, and rotating the driving wheel to rotate the workpiece mounting part."

In addition, in order to set the workpiece W in a vertical and flat posture with respect to the optical axis of the exposure head in the exposure area, it is preferable to adjust the tension in the rotating mechanism 21. For example, when a flexible component as described above is used as the workpiece mounting portion, when the workpiece W passes through the exposure area and becomes loose, the posture of the workpiece W will change, resulting in a decrease in exposure accuracy. Therefore, it is preferable to apply appropriate tension to the workpiece mounting portion at least when passing through the exposure area. As a structure for this purpose, it can be achieved by applying an appropriate reverse torque to the driven wheel 23. That is, when the driving wheel 22 rotates and pulls the workpiece mounting portion, a reverse torque is applied to the driven wheel 23, and the driving wheel 22 rotates in opposition to it.

The above-mentioned structure is also effective when it is connected to a non-flexible workpiece mounting part such as the platform 3. In the structure connected to the non-flexible member, there is a backlash in the connection part. Due to the influence of the backlash, the workpiece mounting part is slightly tilted in the exposure area, so there is a situation where the exposure accuracy is reduced. In order to prevent this situation, it is similarly set to a state where a reverse torque is applied to the driven wheel 23 and the workpiece mounting part is pulled from both sides.

In addition, in the operation of the above-mentioned direct drawing exposure device, the rotating mechanism 21 rotates each platform 3 at a constant speed, and does not stop moving in particular during the normal operation of the device. However, there may be a situation where a sequence of stopping at an appropriate time point is adopted as needed. For example, there is a situation where it is easier to implement when the workpiece W is pre-aligned and placed on the platform 3, and in this case, there may be a situation where the operation of the rotating mechanism 21 is temporarily stopped. After the workpiece W is placed in the pre-aligned state, the rotating mechanism 21 restarts the operation. In addition, there is a situation where it is better to stop when the camera element 61 is shooting, and in this case, there is a situation where the movement is temporarily stopped. In this way, when the movement is temporarily stopped, the workpiece W is not located in the exposure area at that time point. The reason is that when it is located in the exposure area, it is difficult to control the exposure time (light quantity). On the contrary, the structure in which the workpiece W does not stop has the meaning that the control of the spatial light modulator 12 in the exposure unit 1 does not become complicated.

In the above-mentioned embodiment, the alignment structure is appropriately changed. For example, when only pre-alignment is used to ensure the required position accuracy, formal alignment is not performed, and the imaging element 61 is not provided. In addition, regarding the autofocus means, there may be a situation where it is not necessary as long as the accuracy of the conveying system 2 is high enough. That is, in the relationship between the focus depth of the projection optical system 13 or the required exposure contrast, there may be a situation where the conveying system 2 does not need an autofocus means as long as it is a mechanism that can sufficiently convey the workpiece W horizontally.

In addition, in the above-mentioned embodiment, although a plurality of exposure units 1 are provided, there may be a case where there is only one exposure unit 1. Also, in the case of a single-sided exposure process, no reversing mechanism 81 is provided and no other adjacent direct-drawing exposure device is provided. Also, as the workpiece W, in addition to a rigid plate-like component, there is also a case where a flexible sheet-like component exists. A typical example is a flexible printed substrate. Moreover, as an exposure process, in addition to the case where the purpose is to form a circuit of such a printed substrate, there is also a case where exposure is performed for the purpose of manufacturing a mechanical microstructure such as MEMS. The direct-drawing exposure device of the above-mentioned structure can be used for various purposes such as this.

1: Exposure unit 2: Transport system 21: Rotation mechanism 22: Driving wheel 23: Driven wheel 3: Platform 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: Reversal mechanism 82: Dust-free test bench 9: Main control unit 90: Exposure sequence program W: Workpiece

[Figure 1] A front view schematic diagram of a direct drawing exposure device of an embodiment. [Figure 2] A plan view schematic diagram of a direct drawing exposure device of an embodiment. [Figure 3] A schematic diagram of an exposure unit in a direct drawing exposure device of an embodiment. [Figure 4] A three-dimensional schematic diagram of an exposure area. [Figure 5] A three-dimensional schematic diagram of a rotary mechanism provided in a conveying system. [Figure 6] A three-dimensional schematic diagram of a connection structure of each platform. [Figure 7] A side view schematic diagram of the adsorption of a workpiece by an adsorption mechanism.

1: Exposure unit

2: Transport system

3: Platform

4: Loader

5: Unloader

7: Vacuum adsorption mechanism

9: Main control unit

21: Rotating mechanism

22: Driving wheel

23: Driven wheel

40: Load into conveyor

41: Adsorption plate

42: Move in the arm

43: Move in the side arm drive mechanism

50: Remove the conveyor

51: Adsorption plate

52: Move out the arm

53: Remove the side arm drive mechanism

61: Imaging components

62: Exposure pattern rewriting program

63: Autofocus sensor

71: Adsorption box

72: Exhaust system

81: Reversal mechanism

82: Dust-free laboratory bench

90: Exposure sequence program

91: Exposure pattern program

900: Memory Department

W: Workpiece

Claims (7)

A direct-drawing exposure device is used to expose each plate-shaped or sheet-shaped workpiece separated from each other by irradiating light of a predetermined pattern without using a mask. The direct-drawing exposure device is characterized in that it has: an exposure head, which irradiates light of a predetermined pattern to a set exposure area; and a conveying system, which conveys each workpiece through the exposure area. The workpiece conveying system has: a rotating mechanism, which rotates a workpiece mounting portion that is perpendicular to the optical axis of the exposure head and is flat along an endless rotation path when passing through the exposure area; a loader, which sequentially mounts each unexposed workpiece on the workpiece mounting portion; and an unloader, which sequentially recovers each exposed workpiece from the workpiece mounting portion. As in claim 1, a direct drawing exposure device is provided with an alignment sensor at the position of "detecting the state of each workpiece on the aforementioned rotating path between the loading position of each unexposed workpiece on the aforementioned loader and the aforementioned exposure area", and an alignment means is provided, and the alignment means corrects the irradiation position of the light of the aforementioned predetermined pattern by the aforementioned exposure head through the signal from the alignment sensor. As in claim 2, the direct-drawing exposure device, wherein the alignment means is a means of "correcting the irradiation position by detecting the state of each of the aforementioned workpieces in motion on the aforementioned rotation path with a signal from the aforementioned alignment sensor". A direct drawing exposure device as claimed in any one of claim 1, 2 or 3, wherein the exposure head comprises: a projection optical system, which forms the light of the predetermined pattern, and an autofocus sensor for "measuring the distance of each workpiece until it is placed on the workpiece placement part" is provided on the rotation path between the loading position of each unexposed workpiece placed by the loader and the exposure area, and an autofocus means for "controlling the projection optical system according to the measurement result of the autofocus sensor" is provided. As in claim 4, the direct-drawing exposure device, wherein the aforementioned autofocus means is a means of "controlling the aforementioned projection optical system according to a signal from the aforementioned autofocus sensor measured on the aforementioned rotation path to the distance of each of the aforementioned workpieces in motion". A direct-drawing exposure device as claimed in claim 1, wherein the device comprises: an adsorption mechanism that adsorbs each of the workpieces placed on the workpiece placement portion to the workpiece placement portion when the workpieces pass through at least the exposure area. A direct-drawing exposure device as claimed in claim 2 or 3, wherein: a suction mechanism is provided to suction each of the workpieces whose state is detected by the alignment sensor to the workpiece mounting portion at least from the time of the detection until the workpiece passes through the exposure area.

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