JP2009075142A - Exposing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable positioning of a substrate to be exposed with a photomask without needing detection of the photomask's position in every positioning by providing a storage means for storing the photomask's positions. <P>SOLUTION: The position of a mask-side reference pattern is stored by the storage means 33 in advance prior to input of the substrate 7 to be exposed to an exposing position, and the substrate 7 is then carried and input to the exposing position to detect the position of a substrate-side reference pattern. The stored position of the mask-side reference pattern is compared with the detected position of the substrate-side reference pattern to position the photomask 12 to the substrate 7, and exposing light is emitted from an exposing light source 3 to the substrate 7 at a predetermined time to expose a predetermined pattern. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention exposes a predetermined pattern by irradiating a substrate to be exposed at a predetermined timing from a light source through a photomask that is conveyed in one direction and aligned with the substrate to be exposed. In detail, the exposure method to be performed includes the storage means for storing the position of the photomask, thereby aligning the substrate to be exposed and the photomask without detecting the position of the photomask each time alignment is performed. The present invention relates to an exposure method capable of

A conventional exposure apparatus includes a stage on which a substrate coated with a photosensitive resin is placed on an upper surface, a mask head disposed above the stage and holding a photomask in close proximity to the substrate, and the substrate Imaging means for capturing and imaging the formed substrate-side alignment mark and the mask-side alignment mark formed on the photomask in the same field of view, and the substrate-side and mask-side alignment marks are captured by the imaging means. Images are taken at the same time, and the stage and the mask head are relatively moved on the basis of the taken images, and the substrate and the photomask are aligned and exposed (for example, Patent Document 1). reference).
JP 2007-102094 A

  However, since the exposure method in the conventional exposure apparatus has no storage means for storing the mask side reference pattern formed on the photomask, the photomask is aligned each time the photomask is aligned with the substrate to be exposed. And the exposed substrate must be imaged simultaneously in the same field of view. Also, if the substrate to be exposed is opaque to the illumination light for imaging due to the aluminum coating for TFT wiring exposure, etc., the illumination light cannot pass through the substrate to be exposed and the reflected light Had to use. For this reason, the arrangement position of the imaging means needs to be on the same side as the photomask arrangement side with respect to the substrate to be exposed, and the space cannot be effectively used. Further, in the existing apparatus in which the imaging means is disposed on the opposite side of the photomask with respect to the substrate to be exposed, the opaque substrate to be exposed as described above cannot be exposed.

  Accordingly, the present invention addresses such problems and includes a storage means for storing the position of the photomask so that the substrate to be exposed and the photomask can be detected without detecting the position of the photomask each time alignment is performed. It is an object of the present invention to provide an exposure method that can be aligned with each other.

  In order to achieve the above object, an exposure method according to the present invention comprises a plurality of mask side reference patterns formed on a photomask in a direction substantially orthogonal to a transport direction of a substrate to be exposed on which a substrate side reference pattern is provided. A step of picking up an image by means of image pickup means in which light receiving elements are arranged in a straight line; a step of processing the picked-up photomask image to detect the position of a mask side reference pattern of the photomask; A step of starting conveyance of the substrate to be exposed toward a substrate imaging position and a substrate exposure position by a conveyance unit on one surface side of the mask; and a substrate-side reference pattern formed on the substrate to be exposed by the imaging unit. Imaging, detecting the position of the substrate-side reference pattern of the substrate to be exposed, and the position of the mask-side reference pattern of the photomask stored in the storage means; Comparing the detected position of the substrate-side reference pattern of the substrate to be detected to calculate a displacement amount between the substrate to be exposed and the photomask, and adjusting the photomask according to the calculated displacement amount. Moving the substrate in a direction orthogonal to the transport direction of the substrate to be exposed and aligning the photomask with the substrate to be exposed; a substrate pattern of the substrate to be exposed transported from the calculated displacement amount; and the photo Calculating a timing at which a position of a mask pattern linearly extending in a direction substantially orthogonal to the transport direction of the substrate to be exposed on the mask is matched, and the exposure to be transported through the aligned photomask Irradiating the substrate with exposure light from the light source at the calculated timing.

  The imaging means is arranged on the opposite side of the photomask with the substrate to be exposed in between. As a result, the mask side reference pattern and the substrate side reference pattern are imaged by the imaging means arranged on the opposite side of the photomask across the substrate to be exposed.

  Further, the imaging means reflects or transmits light from the surface of the photomask and passes through a condensing lens provided on the front side of the light path of the light receiving element, and reflects or transmits from the surface of the exposed substrate and collects the light. An optical distance correction unit is provided that forms an image of light transmitted through the optical lens on a light receiving surface formed by arranging the plurality of light receiving elements in a straight line. Thus, the optical distance correction means reflects or transmits the light reflected or transmitted from the surface of the photomask and transmitted through the condenser lens provided on the front side of the optical path of the light receiving element, and reflected or transmitted from the surface of the exposed substrate. The light transmitted through the condensing lens forms an image on a light receiving surface formed by arranging the plurality of light receiving elements in a straight line.

  The optical distance correction means is made of a transparent member having a predetermined refractive index disposed on an optical path connecting at least the light receiving surface of the imaging means and a photomask. Thereby, by the optical distance correction means composed of a transparent member having a predetermined refractive index, the light reflected or transmitted from the surface of the photomask and transmitted through the condenser lens provided on the front side of the optical path of the light receiving element, The light reflected or transmitted from the surface of the substrate to be exposed and transmitted through the condenser lens is imaged on a light receiving surface formed by arranging the plurality of light receiving elements in a straight line.

  According to the first aspect of the present invention, the mask-side reference pattern is imaged by the imaging unit, the image of the captured photomask is processed to detect the position of the mask-side reference pattern, and is stored in the storage unit. On one surface side of the photomask, the conveyance means starts conveying the substrate to be exposed toward the substrate imaging position and the substrate exposure position, and the substrate-side reference pattern is imaged by the imaging means. Detecting the position, comparing the position of the mask-side reference pattern stored in the storage means and the position of the detected substrate-side reference pattern, and calculating the amount of displacement between the exposed substrate and the photomask, The photomask is moved in a direction orthogonal to the transport direction of the substrate to be exposed in accordance with the calculated displacement amount of the exposure substrate, the photomask is aligned with the substrate to be exposed, and the calculation is performed. The timing at which the substrate pattern of the substrate to be transported to be transferred matches the position of the mask pattern provided on the photomask is calculated from the amount of positional deviation, and the position is adjusted via the aligned photomask. Exposure light can be irradiated from the light source to the substrate to be exposed at the calculated timing. Thereby, the position of the mask side reference pattern is stored in advance by the storage means before the substrate to be exposed is put into the exposure position, and after the substrate is put in, the position of the mask side reference pattern is aligned each time. The position of the photomask relative to the substrate to be exposed can be aligned by comparing the position of the detected substrate-side reference pattern. Therefore, it is not necessary to simultaneously image the photomask and the substrate to be exposed within the same field of view every time the photomask is aligned with the substrate to be exposed. In addition, even when the substrate to be exposed is opaque to the illumination light for imaging, it is not necessary to transmit the illumination light to the substrate to be exposed. Therefore, it can be on the side opposite to the photomask placement side, and the space can be used effectively. For this reason, even in an existing apparatus in which the image pickup means is disposed on the opposite side of the photomask from the substrate to be exposed, the opaque exposure as described above can be performed by a simple change such as addition of a storage means. The present invention can also be applied to substrate exposure.

  According to the second aspect of the present invention, the mask-side reference pattern and the substrate-side reference pattern can be imaged by the imaging means disposed on the opposite side of the photomask across the substrate to be exposed. . As a result, the position of the mask side reference pattern is stored in advance by the storage means before the substrate to be exposed is input to the imaging position, and then the substrate to be exposed is transported and input to the imaging position. Illuminating light for imaging by comparing the position of the stored mask-side reference pattern with the detected position of the substrate-side reference pattern and aligning the photomask with respect to the exposed substrate. However, the present invention can also be applied to a substrate to be exposed that is opaque. In addition, the number of devices arranged on the photomask side can be reduced, and space can be effectively used.

  Further, according to the invention of claim 3, the light that has been reflected or transmitted from the surface of the photomask by the optical distance correction means and passed through the condenser lens provided on the front side of the optical path of the light receiving element, and The light reflected or transmitted from the surface of the exposure substrate and transmitted through the condenser lens can be imaged on a light receiving surface formed by arranging the plurality of light receiving elements in a straight line. Therefore, it is not necessary to move the image pickup means in the optical axis direction in order to match each optical distance between the photomask image pickup and the exposure substrate image pickup, and a positional shift occurs due to the movement shift of the image pickup means. Therefore, the alignment accuracy can be improved.

  According to the fourth aspect of the present invention, the optical distance correction means made of a transparent member having a predetermined refractive index reflects or transmits from the surface of the photomask and is provided on the front side of the optical path of the light receiving element. The light transmitted through the condenser lens and the light reflected or transmitted from the surface of the substrate to be exposed and transmitted through the condenser lens are both imaged on a light receiving surface formed by arranging the plurality of light receiving elements in a straight line. Can be made. Therefore, the optical distance can be corrected with a simple configuration.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic view showing an embodiment of an exposure apparatus used in the exposure method according to the present invention. The exposure apparatus conveys the substrate to be exposed in one direction and irradiates the substrate to be exposed from the light source at a predetermined timing through a photomask aligned with the substrate to be exposed to form a predetermined pattern. The exposure means comprises a transport means 1, a mask head 2, an exposure light source 3, an imaging means 4, illumination light sources 5a, 5b, 5c, and a control means 6. In the following description, the case where the substrate to be exposed is composed of a TFT substrate 7 described later coated with aluminum for TFT wiring exposure will be described.

  The transport means 1 is for placing the TFT substrate 7 on the upper surface of the stage 8 as a placement surface and transporting it in the direction of arrow A. A stage drive motor 41 (see FIG. 7) described later is controlled by the control means 6 described later. The stage 8 is driven under control. Further, the transport means 1 is provided with a position detection sensor and a speed sensor such as an encoder 9 (see FIG. 7) described later and a linear sensor, for example, and the output is fed back to the control means 6 to detect the position. Speed control is possible. The stage 8 is provided with an opening (not shown) corresponding to the entire area of the TFT substrate 7, and the TFT substrate 7 can be imaged from below by the imaging means 4 disposed below the stage 8. It is like that.

  A mask head 2 is provided above the conveying means 1. The mask head 2 holds a photomask 12 provided with a plurality of mask patterns 11 (see FIG. 2) in close proximity to the TFT substrate 7 with a gap of, for example, 100 to 300 μm. An opening is provided corresponding to the region of the mask 12 where the plurality of mask patterns 11 are formed, and the peripheral edge of the photomask 12 is held. The mask head 2 is controlled by the control means 6 and can move in a direction (arrow B direction in FIG. 2) substantially perpendicular to the transport direction of the TFT substrate 7 (arrow A direction in FIG. 1). The mask 12 can be displaced. In this case, the means for driving the mask head 2 is formed by combining a mask head driving motor 51 (see FIG. 7) described later, a ball screw, and a guide rail.

  Here, as shown in FIG. 2, the photomask 12 includes a transparent base material 13, a light shielding film 14, a mask pattern 11, and a mask side alignment mark 15.

  The transparent substrate 13 is a transparent glass plate that transmits ultraviolet light and visible light with high efficiency, and is made of, for example, quartz glass. As shown in FIG. 3A or 3B, a light shielding film 14 is formed on one surface 13 a of the transparent base material 13. The light shielding film 14 shields exposure light and is formed of an opaque thin film, for example, a thin film of chromium (Cr).

A plurality of mask patterns 11 are formed on the light shielding film 14 as shown in FIG. The plurality of mask patterns 11 are openings having a predetermined shape that can irradiate the TFT substrate 7 conveyed facing the photomask 12 with exposure light, and are formed on the TFT substrate 7 in substantially the same shape. It is transferred onto the pattern 16 (see FIG. 4). In this embodiment, the mask pattern 11 is formed of a straight line portion 17, a convex portion 18, and a rectangular portion 19, and the straight line portion 17 is the mask movement direction of the photomask 12 (in the direction of arrow B in FIG. 2). ) Is extended linearly from the vicinity of one end 12a to the vicinity of the other end 12b. Further, a plurality of convex portions 18 are formed in a convex shape at a predetermined interval in the longitudinal direction on the side of the straight portion 17 on the front side in the substrate transport direction. Further, the rectangular portion 19 is formed at a predetermined distance from the convex portion 18 toward the front side in the substrate transport direction. Then, for example, the lower edge of the protrusion 18 located near the center portion of the mask moving direction of the photomask 12 is set in advance as a reference position M _1. Although FIG. 2 shows the case where the mask patterns 11 are arranged in two rows, the mask pattern 11 may be one row.

Further, as shown in FIG. 2, a plurality of mask-side alignment marks 15 are formed side by side on the light-shielding film 14 from the central side in the mask moving direction of the photomask 12 toward the other end 12b. . The plurality of mask side alignment marks 15 are positions between a reference position M ₁ preset on the mask pattern 11 and a reference position M ₂ preset on a substrate pattern 16 of the TFT substrate 7 described later (see FIG. 4). The mask side reference pattern to be aligned is formed corresponding to the mask pattern 11. Further, the formation position is set so that the lower edge of the mask alignment mark 15 in FIG. 2 coincides with the lower edge of the projection 18 of the corresponding mask pattern 11. For example, a mask side alignment mark 15 formed on the center side in the mask moving direction of the photomask 12 is preset as a reference mark 15a. Thus, by substrate-side alignment mark 22 of the said reference mark 15a TFT substrate 7 (see FIG. 4) are adjusted in position so that a predetermined positional relationship, the reference position M ₁ of the mask pattern 11 A reference position M ₂ of a TFT substrate 7 described later can be aligned.

  Further, as shown in FIG. 3A, an ultraviolet antireflection film 21 is formed in a region corresponding to the formation region of the mask pattern 11 on the other surface 13b of the transparent substrate 13 (see FIG. 2). Therefore, the transmission efficiency of the ultraviolet component contained in the exposure light can be improved.

Here, the TFT substrate 7 to be used is one in which an opaque film made of aluminum or the like is coated on one surface of a transparent glass substrate, and a substrate-side reference pattern is formed on the surface by a resist. As shown in FIG. 4, the substrate-side reference pattern includes a substrate pattern 16, a substrate-side alignment mark 22, and an alignment confirmation mark 23. The substrate pattern 16 indicates an exposure pattern of exposure light irradiated from the exposure light source 3 to be described later through the photomask 12, and is used for alignment between the photomask 12 and the TFT substrate 7. The mask 12 is formed in substantially the same shape as the mask pattern 11, and includes a linear portion 55, a convex portion 24, and a rectangular portion 57 corresponding to the mask pattern 11, and a plurality of them are equally spaced from the front side to the rear side in the substrate transport direction. A column is provided. Further, the lower right corner of the convex portion 24 positioned near the center portion of the mask moving direction of the substrate pattern 16 is set in advance as the reference position M _2. In addition, a substrate-side alignment mark 22 is provided at a substantially central portion in the mask moving direction on the front side in the transport direction of the TFT substrate 7. The substrate-side alignment mark 22 corrects a positional deviation between a reference position M ₁ preset on the photomask 12 (see FIG. 2) and a reference position M ₂ preset on the TFT substrate 7. It is for taking alignment, and is formed in an elongated shape with the substrate transport direction as the longitudinal direction. Further, a plurality of alignment confirmation marks 23 are formed on the side of the substrate-side alignment mark 22 so as to correspond to the convex portions 24 from the center side in the mask moving direction toward the one end 7a. The substrate-side alignment mark 22 and the alignment confirmation mark 23 are formed so that the lower edge of each mark coincides with the lower edge of the corresponding projection 24 in FIG.

An exposure light source 3 is provided above the mask head 2 as shown in FIG. The exposure light source 3 emits exposure light to the TFT substrate 7 through the photomask 12, and is a flash lamp that emits ultraviolet light that is controlled by the control means 6 to be turned on and off. The exposure light emitted from the exposure light source 3 is collimated by, for example, a condenser lens 25 and irradiates the photomask 12.

  An imaging unit 4 is provided below the stage 8 of the transport unit 1. The imaging means 4 images the substrate pattern 16 (see FIG. 4) formed on the TFT substrate 7 and the mask side alignment mark 15 (see FIG. 2) formed on the photomask 12, respectively. 7 is a line camera having a line CCD composed of a plurality of light receiving elements 26 arranged in a straight line in a direction substantially orthogonal to the conveying direction 7. Specifically, the line CCD 26 and the substrate pattern 16 formed on the TFT substrate 7 and the mask side alignment mark 15 formed on the photomask 12 are arranged on the light receiving surface of the line CCD 26. And a condensing lens 27 that forms an image on the optical axis, and an optical distance correction means 28 provided between the line CCD 26 and the condensing lens 27.

  As shown in FIG. 5, the optical distance correction means 28 is irradiated from an illumination light source 5a, which will be described later, provided above the stage 8 (see FIG. 1), passes through the surface of the photomask 12, and passes through the line CCD 26. The light transmitted through the condenser lens 27 provided on the front side of the optical path and the illumination light sources 5b and 5c described below provided below the stage 8 as shown in FIG. The light reflected by the surface of the TFT substrate 7 and transmitted through the condenser lens 27 is imaged on the light receiving surface formed by the line CCD 26, and is more than the refractive index of air. It consists of a transparent member having a large predetermined refractive index, for example a glass plate. As a result, the substrate-side reference pattern such as the substrate pattern 16 of the TFT substrate 7 and the mask-side alignment mark 15 of the photomask 12 that are shifted in the optical axis direction of the imaging means 4 (see FIG. 1) and the mask-side alignment mark 15 of the photomask 12 are placed on the same light receiving surface. The image can be taken in focus.

  As shown in FIG. 1, a transmission illumination light source 5a is provided above the stage 8 of the transfer means 1 so as to face the photomask 12, and below the stage 8, the TFT substrate is provided. Opposing illumination light sources 5b and 5c for reflection are provided. The illumination light sources 5a, 5b, and 5c emit illumination light composed of visible light to illuminate the TFT substrate 7 and the photomask 12, and the imaging unit 4 uses the substrate-side reference pattern of the TFT substrate 7 and the mask of the photomask 12 to illuminate. The side reference pattern can be imaged, such as a halogen lamp. The illumination light source 5a above the photomask 12 is installed in a direction to irradiate the imaging light 4 directly below the imaging unit 4 with illumination light, and transmits the photomask 12 to transmit the photomask 12 Twelve mask-side alignment marks 15 can be imaged. Further, the illumination light sources 5b and 5c below the TFT substrate 7 are installed so as to irradiate the area of the TFT substrate 7 located immediately above the image pickup means 4 with illumination light in the vicinity of the front and rear of the image pickup means 4. Then, the substrate side reference pattern such as the substrate pattern 16 of the TFT substrate 7 can be imaged by being reflected by the TFT substrate 7. An ultraviolet cut filter (not shown) is provided in front of the illumination light sources 5b and 5c in the radiation direction, and the TFT substrate 7 is irradiated with ultraviolet rays contained in visible light emitted from the illumination light sources 5b and 5c. The resist is prevented from being exposed.

  The transport means 1, mask head 2, exposure light source 3, imaging means 4 and illumination light sources 5 a to 5 c are connected to the control means 6. The control means 6 processes the image picked up by the image pickup means 4, calculates the amount of shift in the mask moving direction of the photomask 12 with respect to the TFT substrate 7, moves the photomask 12 and aligns it. The amount of displacement of the position of the TFT substrate 7 in the substrate transport direction with respect to the photomask 12 is calculated, and the timing at which the substrate pattern 16 of the TFT substrate 7 and the position of the mask pattern 11 of the photomask 12 match is calculated. The exposure light source 3 is turned on at the calculated timing, and the TFT substrate 7 is irradiated with exposure light. As shown in FIG. 7, a stage controller 29, an imaging means controller 31, and a mask movement direction image processing unit 32 are provided. Storage means 33, mask movement distance calculation circuit 34, mask head drive circuit 35, substrate transport direction image processing unit 36, lighting position A calculating circuit 37, and a position comparison circuit 38, a light source drive circuit 39, a.

  The stage controller 29 moves the stage 8 of the conveying means 1 shown in FIG. 1 at a predetermined speed in the direction of arrow A, and feeds back the output of the stage encoder 9 to control the speed of the stage 8 via the stage drive motor 41. It is supposed to be.

The imaging means controller 31 receives an imaging start signal from the input means 42 and controls the illumination light sources 5a to 5c (see FIG. 1) to be turned on and off, and the imaging means 4 to start and end imaging. Is.

  A pixel interpolation memory 44 is connected to the output side of the imaging means 4. The pixel interpolation memory 44 receives the image data picked up from the image pickup means 4 and stores the image data as the number of pixels determined by the line CCD 26 of the image pickup means 4. By sequentially storing images stored as one-dimensional information, a two-dimensional image is formed.

  A mask movement direction image processing unit 32 is connected to the output side of the pixel interpolation memory 44. The mask movement direction image processing unit 32 detects necessary information in the mask movement direction from the images of the TFT substrate 7 and the photomask 12 captured by the imaging unit 4 and stored in the pixel interpolation memory 44. The mask movement direction pixel interpolation circuit 45, the mask movement direction edge extraction circuit 46, and the mask movement direction edge selection circuit 47 are formed.

  The mask movement direction pixel interpolation circuit 45 is connected to the output side of the pixel interpolation memory 44. The mask movement direction pixel interpolation circuit 45 receives image data from the pixel interpolation memory 44 and sequentially interpolates pixels in the mask movement direction for each column.

  A mask movement direction edge extraction circuit 46 is connected to the output side of the mask movement direction pixel interpolation circuit 45. The mask movement direction edge extraction circuit 46 receives the pixel-interpolated image data from the pixel interpolation circuit 45, recognizes and extracts a line segment having a predetermined length extending in a direction orthogonal to the mask movement direction as a mask movement direction edge. To do.

A mask movement direction edge selection circuit 47 is connected to the output side of the mask movement direction edge extraction circuit 46. The mask movement direction edge selection circuit 47 includes the mask side alignment mark 15, the substrate side alignment mark 22, the alignment confirmation mark 23, among the plurality of mask movement direction edges extracted by the mask movement direction edge extraction circuit 46. Only edges necessary for alignment of the reference position M _{2 and the} like are selected.

  A storage means 33 and a mask movement distance calculation circuit 34 are connected to the output side of the mask movement direction edge selection circuit 47. The storage means 33 stores information on the mask movement direction edge of the photomask 12 selected by the mask movement direction edge selection circuit 47, and transmits and receives the information to and from the mask movement distance calculation circuit 34 to thereby transmit the photomask. 12 is used to update information on 12 mask movement direction edges, and includes a mask memory update circuit 48 and a mask memory 49.

  The mask memory update circuit 48 is connected to the output side of the mask movement direction edge selection circuit 47 and transmits / receives to / from the mask movement distance calculation circuit 34 to thereby update the information in the mask memory 49. The information in the mask memory 49 is updated when it is determined whether or not it is necessary.

  A mask memory 49 is connected to the output side of the mask memory update circuit 48. The mask memory 49 stores the latest position information of the photomask 12 by transmitting and receiving with the mask memory update circuit 48.

The mask moving distance calculating circuit 34, the substrate side alignment mark 22 of the TFT substrate 7 which is selected by the mask moving direction edge selection circuit 47, and the alignment check mark 23 and the reference position M _2, which is stored by the storage means By comparing the mask side alignment mark 15, the reference mark 15 a and the reference position M _{1 of the} photomask 12, the amount of shift in the mask moving direction between the TFT substrate 7 and the photomask 12 is calculated.

  A mask head drive circuit 35 is connected to the output side of the mask movement distance calculation circuit 34. The mask head drive circuit 35 moves the photomask 12 by the amount of deviation in the mask movement direction between the TFT substrate 7 and the photomask 12 calculated by the mask movement distance calculation circuit 34. A drive control signal is sent to the mask head drive motor 51 connected to the output side of the mask head drive circuit 35.

  The substrate transport direction image processing unit 36 detects necessary information in the substrate transport direction in the image of the TFT substrate 7 imaged by the imaging means 4, and includes a substrate transport direction pixel interpolation circuit 52 and a substrate transport direction. An edge extraction circuit 53 and a substrate transport direction edge selection circuit 54 are formed.

  The substrate transport direction pixel interpolation circuit 52 is connected to the output side of the pixel interpolation memory 44. The substrate transport direction pixel interpolation circuit 52 receives image data stored as two-dimensional information from the pixel interpolation memory 44 and interpolates pixels in the substrate transport direction.

  A substrate transport direction edge extraction circuit 53 is connected to the output side of the substrate transport direction pixel interpolation circuit 52. The substrate transport direction edge extraction circuit 53 receives the image-interpolated image data from the pixel interpolation circuit 52, recognizes and extracts a line segment of a predetermined length extending in a direction orthogonal to the substrate transport direction as a mask movement direction edge. To do.

  A substrate transport direction edge selection circuit 54 is connected to the output side of the substrate transport direction edge extraction circuit 53. The substrate transport direction edge selection circuit 54 includes a plurality of substrate transport direction edges extracted by the substrate transport direction edge extraction circuit 53, such as the leading edge 56 in the transport direction of the linear portion 55 (see FIG. 4). Only the edges necessary for detecting the substrate transfer position are selected.

  A lighting position calculation circuit 37 is connected to the output side of the substrate transport direction edge selection circuit 54. The lighting position calculation circuit 37 calculates a displacement amount of the position of the TFT substrate 7 in the substrate transport direction with respect to the photomask 12, and the substrate pattern 16 and the photo pattern of the TFT substrate 7 are calculated from the calculated displacement amount of the position. The timing at which the position of the mask pattern 11 of the mask 12 matches is calculated.

  A position comparison circuit 38 is connected to the output side of the lighting position calculation circuit 37. The position comparison circuit 38 detects the timing at which the substrate pattern 16 of the TFT substrate 7 calculated by the lighting position calculation circuit 37 matches the position of the mask pattern 11 of the photomask 12 by the stage encoder 9. The actual position information of the TFT substrate 7 is compared.

  A light source drive circuit 39 is connected to the output side of the position comparison circuit 38. The light source driving circuit 39 determines whether or not the exposure light source 3 can be turned on from the position information compared by the position comparison circuit 38, and controls the turning on and off of the exposure light source 3.

Next, the operation of the exposure apparatus configured as described above and the exposure method performed using the exposure apparatus will be described.
First, as shown in FIG. 1, the photomask 12 is placed with the light-shielding film 14 side down, and the mask-side alignment mark 15 (see FIG. 2) is positioned on the near side of the TFT substrate 7 in the substrate transport direction. The mask pattern 11 (see FIG. 2) is placed on the mask head 2 so that the longitudinal direction of the linear portion 17 is substantially orthogonal to the transport direction. Next, on the TFT substrate 7, the mask-side alignment mark 11 of the photomask 12 is placed on the stage 8 of the transport means 1 with the resist-coated surface on the top surface and the substrate-side alignment mark 22 facing the leading side in the transport direction. It is placed on the near side in the substrate transport direction. Thereby, as shown in FIG. 5, a state where the TFT substrate 7 is not yet input is formed below the photomask 12. Then, when an exposure start signal is input by the input means 42 (see FIG. 7), an exposure operation is executed according to the following procedure.

  First, in step S1 shown in FIG. 8, the mask side reference pattern formed on the photomask 12 shown in FIG. Specifically, as shown in FIG. 1, the imaging means controller 31 (see FIG. 7) turns on the illumination light source 5a above the photomask 12 and irradiates illumination light, thereby forming a reference pattern of the photomask 12. The mask side alignment mark 15 (refer to FIG. 2) to be transmitted is imaged by the imaging means 4.

Next, in step S2, the mask moving direction edge extracting unit and the mask moving direction edge selecting unit extract and detect the edge of the mask side reference pattern in the mask moving direction and detect it, and store it in the storage unit 33 (see FIG. 7). To do. Specifically, as shown in FIG. 7, the image captured in step S 1 is first stored in the pixel interpolation memory 44, and pixels in the mask movement direction are interpolated by the mask movement direction pixel interpolation circuit 45. . Next, the mask movement direction edge extraction circuit 46 recognizes and extracts a line segment of a predetermined length extending in a direction orthogonal to the mask movement direction of the mask side reference pattern as a mask movement direction edge. Next, the mask moving direction edge selection circuit 47, from the plurality of mask moving direction edges the extracted mask-side alignment mark 15 (see FIG. 2) and the reference marks 15a and reference position M ₁ is selected. Next, the cell number of the light receiving element of the line CCD 26 (see FIG. 1) where the selected mask side alignment mark 15 and the reference mark 15a are detected is stored in the mask memory 49.

  Next, in step S3, the transport unit 1 shown in FIG. 1 starts transporting the TFT substrate 7 toward the substrate imaging position and the substrate exposure position.

  Next, in step S4, the substrate-side reference pattern formed on the TFT substrate 7 shown in FIG. 4 is imaged by the imaging means 4 (see FIG. 1). Specifically, as shown in FIG. 6, when the TFT substrate 7 is transported above the imaging position, as shown in FIG. 1, illumination below the TFT substrate 7 is performed by the imaging means controller 31 (see FIG. 7). The light sources 5b and 5c are turned on and reflected by the substrate-side alignment mark 22 (see FIG. 4), the alignment confirmation mark 23, the substrate pattern 16 and the like of the TFT substrate 7 that forms the substrate-side reference pattern when illuminated with illumination light, and captures an image. The reflected light is imaged by the means 4.

In step S5, the mask moving direction edge extracting unit and the mask moving direction edge selecting unit extract and detect the edge of the substrate side reference pattern in the mask moving direction. Specifically, the image captured in step S4 is first stored in the pixel interpolation memory 44 shown in FIG. 7, and the mask movement direction pixel interpolation circuit 45 interpolates pixels in the mask movement direction. Next, the mask movement direction edge extraction circuit 46 recognizes and extracts a line segment of a predetermined length extending in a direction orthogonal to the mask movement direction of the mask side reference pattern as a mask movement direction edge. Next, the mask moving direction edge selection circuit 47, from the plurality of mask moving direction edges the extracted, the substrate side alignment marks 22 and the alignment check mark 23 and the reference position M ₂ shown in FIG. 4 is selected.

Next, in step S6, the amount of displacement of the position of the photomask 12 in the mask moving direction with respect to the TFT substrate 7 shown in FIG. Specifically, first, the cell number of the light receiving element of the line CCD 26 that detected the substrate-side alignment mark 22 (see FIG. 4) of the TFT substrate 7 detected in step S5, and the photomask 12 stored in step S2. The cell number of the light receiving element on the line CCD 26 where the reference mark 15a (see FIG. 2) is detected is read, and the distance L (see FIG. 9) between the light receiving elements represented by the cell number is calculated. Then, it is compared with a predetermined distance L ₀ (see FIG. 10) that has been set and stored in advance, and a deviation amount is calculated.

Next, in step S 7, the photomask 12 is moved according to the calculated position shift amount and aligned with the TFT substrate 7 in the mask moving direction. Specifically, as shown in FIG. 9, when the photomask 12 is displaced in the arrow C direction with respect to the TFT substrate 7, as shown in FIG. 10, the substrate-side alignment mark 22 and the reference mark 15a photomask 12 is moved in the direction of arrow D as the distance L becomes a predetermined distance L _0. As a result, the reference position M ₁ of the photomask 12 matches the reference position M ₂ of the TFT substrate 7.

  Next, as shown in FIG. 10, the cell number of the light receiving element on the line CCD 26 indicating the position of each alignment confirmation mark 23 on the TFT substrate 7 detected in step S5, and each photomask 12 stored in step S2. The cell number of the light receiving element on the line CCD 26 indicating the position of the mask side alignment mark 15 is read, and the average value of each cell number is calculated, whereby each detected alignment confirmation mark 23 and each stored mask side alignment are stored. The average position of the mark 15 is calculated. Then, the average value is compared with the cell number of the light receiving element indicating the position of the line CCD 26 where the substrate side alignment mark 22 of the TFT substrate 7 is detected immediately after alignment adjustment. It is judged that it was done reliably.

  Further, after step S4, step S8 is performed simultaneously with step S5. In step S8, the edge in the transport direction of the substrate-side reference pattern is extracted and selected by the substrate transport direction edge extracting means and the substrate transport direction edge selecting means. Specifically, the image captured in step S4 is first stored in the pixel interpolation memory 44 as shown in FIG. 7, and the substrate transport direction pixel interpolation circuit 52 interpolates the pixels in the substrate transport direction. . Next, a line segment having a predetermined length extending in a direction orthogonal to the substrate transport direction of the substrate-side reference pattern is recognized and extracted as a substrate transport direction edge by the substrate transport direction edge extraction circuit 53. Next, the leading edge of the linear portion 55 of the substrate pattern 16 shown in FIG. 4 located on the leading side in the substrate transport direction among the plurality of extracted substrate transport direction edges by the substrate transport direction edge selection circuit 54. The part 56 is selected.

  Next, in step S9, as shown in FIG. 10, the amount of deviation of the position of the TFT substrate 7 in the substrate transport direction with respect to the photomask 12 is calculated by the lighting position calculation means. Specifically, at the time when the leading edge 56 located on the leading side in the substrate transport direction of the linear portion 55 of the TFT substrate 7 detected in step S8 is captured by the light receiving element of the line CCD 26 (see FIG. 1). The distance E from the line CCD to the edge 20 located on the front side in the substrate transport direction of the linear portion 17 of the mask pattern 11 formed on the photomask 12 is the amount of deviation.

  Next, in step S10, the timing at which the substrate pattern 16 of the TFT substrate 7 matches the position of the mask pattern 11 is calculated from the calculated positional deviation amount E. Specifically, after the elapse of time T, the distance E is divided by the transport speed V of the TFT substrate 7 from the moment when the leading edge 56 of the TFT substrate 7 is captured by the light receiving element of the line CCD 26 (see FIG. 1). However, this is the timing when the substrate pattern 16 of the TFT substrate 7 and the position of the mask pattern 11 coincide.

  Next, in step S <b> 11, the exposure light source 3 is turned on at the calculated timing, and the TFT substrate 7 is irradiated with exposure light via the photomask 12.

  Next, in step S12, it is confirmed whether or not the exposure has been completed up to the last column of the substrate pattern 16 formed on the TFT substrate 7 in a plurality of rows. Returning to the stage, the following steps are repeated, and when the completion is confirmed, the exposure is terminated.

  In the embodiment, the case where the substrate-side alignment mark 22 and the alignment confirmation mark 23 are formed on the TFT substrate 7 has been described. However, the present invention is not limited to this, and the substrate-side alignment mark 22 and the alignment confirmation mark 23 are not provided. Also good. In this case, another alignment mark is formed at a predetermined position on both sides of the TFT substrate 7 in the transport direction, and an alignment mark is formed on both ends of the photomask 12 correspondingly. The alignment may be performed by coarsely adjusting the alignment with the alignment mark.

  In the embodiment, the illumination light source 5a is disposed above the photomask 12, the illumination light sources 5b and 5c are disposed below the TFT substrate 7, and the photomask 12 is imaged by illumination of the illumination light source 5a. Although the TFT substrate 7 is imaged by illumination of the illumination light sources 5b and 5c, the present invention is not limited to this. Only the illumination light source 5b or 5c is provided, and the photomask 12 and the TFT substrate 7 are imaged only by the illumination light source 5b or 5c. You may go.

  In the above description, the case where the substrate is the opaque TFT substrate 7 has been described. However, the present invention is not limited to this, and any substrate that can form a predetermined exposure pattern may be used regardless of whether it is transparent or opaque. It may be.

It is a schematic diagram which shows embodiment of the exposure apparatus used for the exposure method by this invention. It is a top view of the photomask used in the said exposure apparatus. 3A and 3B are cross-sectional views showing the photomask, wherein FIG. 3A is a cross-sectional view taken along the line XX of FIG. 2, and FIG. 3B is a cross-sectional view taken along the line Y-Y of FIG. 2 is a plan view of a TFT substrate used in the exposure apparatus. FIG. It is explanatory drawing which shows the imaging state of the imaging means with which the said exposure apparatus was equipped before board | substrate to be exposed was thrown. It is explanatory drawing which shows the imaging state of the imaging means with which the said exposure apparatus was equipped after board | substrate to be exposed was supplied. It is a block diagram which shows the internal structure of the control means of the said exposure apparatus. It is a flowchart explaining operation | movement of the exposure apparatus used for the exposure method by this invention. It is a figure explaining alignment adjustment with the photomask shown in FIG. 2, and the TFT substrate shown in FIG. 4, and is explanatory drawing which shows the state before adjustment. It is a figure explaining alignment adjustment with the photomask shown in FIG. 2, and the TFT substrate shown in FIG. 4, and is explanatory drawing which shows the state which adjustment of the mask moving direction was complete | finished.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Conveyance means 2 ... Mask head 3 ... Exposure light source 4 ... Imaging means 6 ... Control means 7 ... TFT substrate (exposed substrate)
DESCRIPTION OF SYMBOLS 11 ... Mask pattern 12 ... Photomask 15 ... Mask side alignment mark (mask side reference pattern)
16 ... Substrate pattern 22 ... Substrate side alignment mark 23 ... Alignment confirmation mark 26 ... Line CCD (light receiving element)
27 ... converging lens 28 ... optical distance correcting means 33 ... storage means 56 ... top-side edge M ₂ ... reference position

Claims (4)

A step of imaging a mask side reference pattern formed on a photomask by an imaging means in which a plurality of light receiving elements are arranged in a straight line in a direction substantially orthogonal to a transport direction of an exposed substrate having a substrate side reference pattern provided on the surface. When,
Processing the captured image of the photomask to detect the position of the mask-side reference pattern of the photomask and storing it in a storage means;
On one surface side of the photomask, the conveyance means starts conveying the substrate to be exposed toward the substrate imaging position and the substrate exposure position;
Imaging the substrate-side reference pattern formed on the substrate to be exposed by the imaging means, and detecting the position of the substrate-side reference pattern of the substrate to be exposed;
The position of the mask-side reference pattern of the photomask stored in the storage means is compared with the detected position of the substrate-side reference pattern of the exposed substrate, and the amount of positional deviation between the exposed substrate and the photomask is calculated. Calculating the stage;
Moving the photomask in a direction perpendicular to the transport direction of the substrate to be exposed according to the calculated amount of positional deviation, and aligning the photomask with the substrate to be exposed;
The timing at which the substrate pattern of the substrate to be exposed conveyed from the calculated displacement amount of the substrate matches the position of the mask pattern that extends linearly on the photomask in a direction substantially orthogonal to the direction of conveyance of the substrate to be exposed. Calculating
Irradiating exposure light from a light source at the calculated timing with respect to the substrate to be transported through the aligned photomask;
The exposure method characterized by performing.   2. The exposure method according to claim 1, wherein the imaging means is disposed on the opposite side of the photomask across the substrate to be exposed.   The imaging means reflects or transmits from the surface of the photomask and passes through a condenser lens provided on the front side of the light path of the light receiving element, and reflects or transmits from the surface of the substrate to be exposed and transmits the condenser lens. 3. An exposure method according to claim 1, further comprising optical distance correction means for forming an image of the light transmitted through the light on a light receiving surface formed by arranging the plurality of light receiving elements in a straight line.   4. The exposure method according to claim 3, wherein the optical distance correcting means comprises a transparent member having a predetermined refractive index and disposed on an optical path connecting at least a light receiving surface of the imaging means and a photomask. .

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