JP2013171988A - Exposure device and exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device in which alignment is possible without using an alignment mark.SOLUTION: From the figures of patterns on a substrate 1 and a photomask 2, a pair of figures at corresponding positions are selected as reference marks 40, 41, the images in the neighborhood of them is captured to obtain a partial image, and then a reference mark model is set in the partial image, and registered in a reference mark register 20. When a substrate 1 to be exposed is carried in, the images in the neighborhood of the reference marks 40, 41 are captured by means of an imaging device 4, and the range of the same image is detected as a reference mark identification range by using the reference mark model registered, thus detecting the figures set as the reference marks 40, 41. Alignment is performed using these figures, i.e., the reference marks 40, 41, followed by exposure.

Description

  The present invention relates to an exposure apparatus and an exposure method for a printed wiring board.

Conventionally, in an exposure apparatus for a printed wiring board, alignment between a substrate and a photomask is performed by providing alignment marks on the substrate and the mask, measuring the center coordinates of these marks, and calculating the deviation between the coordinates. It is common to perform position adjustment (Patent Document 1). In addition, in an exposure apparatus in the semiconductor field, an alignment method using an XY scribe line intersection on a wafer instead of an alignment mark is known as an alignment method that does not use an alignment mark (Patent Document 2).
However, there are cases where alignment marks cannot be provided on printed wiring boards and photomasks due to process reasons, and in that case, mechanical alignment is performed using positioning pins or the like. In the production of a printed wiring board having a high density pattern, the accuracy is insufficient.
On the other hand, in the printed circuit board manufacturing process, there is a process of further exposing the pattern to the substrate on which the pattern has already been formed to remove the insulating layer. In this step, there is a corresponding portion between the pattern formed on the substrate and the pattern drawn on the photomask, and there is a figure whose position matches.

JP 20003-107756 JP JP 7-335722 A

  The present invention has been made in view of the current state of the prior art, and provides an exposure apparatus that can perform alignment between a printed wiring board and a photomask with high accuracy without using alignment marks. In particular, an object of the present invention is to provide an exposure apparatus suitable for application to alignment during exposure after solder resist coating.

In order to achieve the above object, the present invention provides a photomask in which a pattern having a figure corresponding to the pattern and having the figure at the same position as the figure is formed on a printed wiring board on which a pattern has already been formed. In the exposure apparatus for a printed wiring board, the shape and size of a pair of figures selected from the figures at the same position are used as a substrate mark and a mask mark for alignment, respectively. An image stored in a partial image of the substrate obtained by photographing the region including the substrate mark, and divided by a predetermined area including the substrate mark, and there is no other identical image in the partial image. Store the selected image as a board reference mark model,
The position of the substrate mark in the substrate reference mark model is stored, and in the partial image of the photomask obtained by photographing the region including the mask mark, an image divided by a predetermined area including the mask mark, A reference mark registration device for storing an image selected so that there is no other identical image in the partial image and unique as a mask reference mark model, and storing a position of the mask mark in the mask reference mark model And an image portion identical to the substrate reference mark model based on the substrate reference mark model stored in the reference mark registration device in an area including the substrate mark imaged when the printed wiring board and the photomask are aligned. Detect as a substrate mark identification range, and detect the substrate mark within the detected substrate mark identification range. Based on the stored mask reference mark model, the same image portion as the mask reference mark model is detected as a mask mark identification range in the area including the mask mark imaged when the printed wiring board and the photomask are aligned. And a reference mark detection device for detecting the mask mark within the detected mask mark identification range, and based on the detected substrate mark and the mask mark, the positions of the printed wiring board and the photomask And performing exposure after the alignment.

According to the exposure apparatus of the present invention, it is possible to align using the figure of the pattern on the substrate and the photomask. In addition, since the reference mark is detected based on the reference mark model registered in the reference mark registration apparatus, other patterns in the pattern are not erroneously detected as reference marks, and high-precision alignment is possible.

The block diagram which shows one Embodiment of this invention. Explanatory drawing which shows operation | movement of one Embodiment of this invention. Explanatory drawing which shows operation | movement of one Embodiment of this invention. Explanatory drawing which shows operation | movement of one Embodiment of this invention. Explanatory drawing which shows operation | movement of one Embodiment of this invention. Explanatory drawing which shows operation | movement of one Embodiment of this invention. The flowchart figure which shows operation | movement of one Embodiment of this invention. The flowchart figure which shows operation | movement of one Embodiment of this invention.

An embodiment of the exposure apparatus of the present invention will be described based on FIG.
The printed wiring board 1 to be exposed is placed on the stage 3, and the stage 3 is movable in the xyz and θ directions.
An optical system 6 is disposed above the stage 3, and a photomask 2 having an exposure pattern is disposed further above the optical system 6. An exposure light source 5 is further disposed above the photomask 2, and is configured to irradiate exposure light from here to expose the pattern on the photomask 2 onto the substrate 1 via the optical system 6. Yes.

Part of the circuit pattern of the substrate 1 and the photomask 2 is selected and registered as the substrate reference mark 40 and the mask reference mark 41. This will be described in detail later.
A plurality of substrate reference marks 40 and mask reference marks 41 may be set at a plurality of locations. In general, it is common to provide two for each, and four for accurate alignment. The number may be three, five, etc., and may be determined as necessary, but the number and position are made to coincide.

The substrate reference mark 40 and the mask reference mark 41 are picked up by the image pickup device 4, processed by the image processing device 13, and sent to the control device 14. The control device 14 moves the stage 3 using the stage control device 11 and the stage position detection device 12, and aligns the substrate 1 and the photomask 2 based on the substrate reference mark 40 and the mask reference mark 41. It is configured.
A plurality of imaging devices 4 may be provided in accordance with the number of substrate reference marks 40 and mask reference marks 41, or a single device may be used.
After the alignment, exposure with exposure light from the exposure light source 5 is performed.

The imaging device 4 has two imaging systems including an optical component 7 such as a mirror that images the substrate reference mark 40 and the camera 10, an optical component 8 such as a mirror that images the mask reference mark 41, and the camera 9.
The position of the image pickup device 4 is controlled by the image pickup device position control device 19, and the image pickup device 4 is positioned at a position where the substrate reference mark 40 and the mask reference mark 41, which are patterns serving as the alignment reference described above, can be picked up. It is configured to match.
The position can be automatically moved by setting from the operation device 18 in advance, or can be moved manually by operating the operation device 18.
Note that the imaging system may be an independent imaging system for the mask 2 and the substrate 1.

Note that the image processing apparatus 13 that processes an image captured by the imaging system can perform image processing and related display via the display unit 15, and settings and the like can be performed by the operation device 16. Yes.
In addition, the control device 14 can instruct the image processing device 13 to perform image processing and make settings related to the image processing, and displays position information calculated from the result of the image processing via the display unit 17. It is configured to be able to.
Further, the control device 14 can control the position of the image pickup system via the operation device 18 or the image processing control device 19 based on the result of the image processing, and the stage position via the stage control device 11 and the stage position detection device 12 as described above. It can be controlled.

A circuit pattern has already been formed on the substrate 1, and an insulating process is performed to protect the pattern, and a photosensitive resin is coated to form an insulating layer. However, it is necessary to remove the insulating layer where the components to be mounted on the circuit pattern on the substrate 1 are joined.
The size and position of the portion from which the insulating layer is removed are drawn on the photomask 2, and the pattern of the photomask 2 is exposed on the substrate 1, and then the insulating layer portion is removed by chemical treatment or the like.

FIG. 2 shows an example of the substrate pattern 31 and the mask pattern 32. Areas 33 and 34 in FIG. 2 indicate the field-of-view range of the imaging device 4. In this embodiment, the areas 33 and 34 are set to the four positions shown in the figure, and alignment is performed at these four positions. Yes. Here, the lower left areas 33 and 34 will be described as an example.
FIG. 3 shows a partial image 38 and a partial image 39 in which the area is enlarged. A superimposed image 37 shown in FIG. 4 is obtained by superimposing the partial image 38 and the partial image 39. By exposing the pattern of the mask pattern 32 onto the substrate pattern 31, the pattern is overlaid like a superimposed image 37, and a process of removing the insulating layer at a predetermined position defined by the exposure of the pattern of the mask pattern 32 is performed. It becomes possible.

Of course, when the mask pattern 32 is exposed on the substrate pattern 31, it is necessary to align the substrate 1 and the photomask 2, but the circuit pattern is already formed on the photomask 2, and an insulating layer is formed. Therefore, the mark formed by the through hole used for the previous exposure is usually buried in the insulating layer and cannot be used. In addition, when there is no space for forming a new alignment mark, or when alignment is performed by dividing the substrate into several regions with respect to the substrate on which the entire substrate is aligned and the circuit is formed, the divided region is used. In some cases, the alignment mark cannot be formed.
Therefore, in the exposure apparatus of the present invention, a part of the pattern already formed on the substrate 1 and a part of the pattern drawn on the photomask 2 are subjected to the substrate reference mark 40 and the mask reference mark 41 by the reference mark registration apparatus 20. Is configured to set as This setting is performed by an operator and registered by the reference mark registration device 20.

First, the operator selects and sets a corresponding arbitrary image from the substrate pattern 31 and the mask pattern 32 for the substrate reference mark 40 and the mask reference mark 41.
At this time, an image at a position where reference mark models 44 and 45 described later can be set is selected.
The patterns set as the substrate reference mark 40 and the mask reference mark 41 are preferably relatively simple patterns such as a circle.

Next, the image pickup device position control device 19 moves the image pickup device 4 to the approximate position based on the position coordinates of the substrate reference mark 40 and the mask reference mark 41 at the position corresponding thereto, and the camera field of view as shown in FIG. The images of the areas 33 and 34 are obtained. This is the partial image 38 and the partial image 39 shown in FIG.
The selected substrate reference mark 40 and mask reference mark 41 exist in the partial image 38 and the partial image 39.

  Next, since there are usually a plurality of identical circuit patterns, there are a plurality of selected substrate reference marks 40 and mask reference marks 41 in the partial image 38 and the partial image 39. In order to automatically detect a substrate reference mark 40 and a mask reference mark 41 selected from a plurality of identical figures, a substrate reference mark model 44 is set from a partial image 38 captured in advance.

As shown in FIGS. 5 and 6, the substrate reference mark model 44 is set by designating an area 42 including the substrate reference mark 40 and cutting out an image as the substrate reference mark model 44. The substrate reference mark model 44 is registered as an image by the reference mark registration device 20, and its shape and size are registered.

  The substrate reference mark model 44 is selected to be the only image in the partial image 38. That is, when an image having the same size as the area 42 is cut out from an arbitrary location of the partial image 38 and compared with the substrate reference mark model 44, there is no place that matches the substrate reference mark model 44 other than the area 42. The area 42 is designated so that there is only one place 42, and this image is used as a substrate reference mark model 44. The substrate reference mark model 44 is rectangular (rectangular) in this embodiment, but may have other shapes.

  In this embodiment, the substrate reference mark model 44 includes the blank area 48 where the pattern outside the pattern 31 including the substrate reference mark 40 does not exist. By appropriately selecting the area of the blank area 48, the area that coincides with the substrate reference mark model 44 and the image 38 can be the area 42 only.

Next, a rectangular substrate reference mark area 54 is set so as to surround the mark 40. The substrate reference mark area 54 is set and registered so that no graphic other than the mark 40 exists.
Then, the position of the substrate reference mark area 54 with respect to the substrate reference mark model 44 is registered.

Similarly, in the mask 2, the area 43 including the mask reference mark 41 is designated in the image 39 captured in advance, the image is cut out and registered as the mask reference mark model 45 including the blank area 49, and information such as the shape and size thereof is stored. sign up. Similarly, a rectangular mask reference mark area 55 is set so as to surround the mark 41. Similarly, the mask reference mark region 55 is set and registered so that there is no figure other than the mark 41 and the position of the mask reference mark region 55 with respect to the substrate reference mark model 45 is registered.
Note that the size and position of the substrate reference mark model 44 and the mask reference mark model 45 do not necessarily match.

  As described above, in the reference mark registration apparatus 20, the shapes and sizes of the substrate reference mark 40 and the mask reference mark 41, the images of the substrate reference mark model 44 and the mask reference mark model 45, the substrate reference mark region 54, and the mask reference mark region 55. And the positional relationship with respect to the models 44 and 45 is set and registered.

Next, detection of the reference marks 40 and 41 will be described. For simplicity, description will be made with reference to FIG.
Based on the contents registered in the fiducial mark registration device 20 as described above, the fiducial marks 40 and 41 are automatically automatically set by the fiducial mark detection device 21 first when aligning the substrate 1 and the photomask 2 during exposure. Detected.
When the substrate 1 to be exposed is carried onto the stage 3, first, a mechanical alignment mechanism (not shown) is used to adjust the position of the substrate 1 with respect to the photomask 2, and on the mask pattern 32. The area 34 including the mask reference mark 41 and the area 33 including the substrate reference mark 40 on the substrate 31 are substantially matched, and this area is simultaneously imaged by the imaging device 4. The partial image 38 ′ and the partial image 39 ′ shown in FIG. 3 are obtained by the two series of imaging systems of the imaging device 4.
The accuracy of the mechanical alignment mechanism may be such that the imaging device 4 can image the mask reference mark 41 and the substrate reference mark 40 simultaneously.

  In the reference mark detection device 21 and the image processing device 13, a range that matches the registered substrate reference mark model 44 is detected from the partial image 38 ′. In this embodiment, the reference mark detection device 21 scans an area of the same size as the substrate reference mark model 44 in the xy direction of the partial image 38 ′ with a predetermined resolution. The same range is detected while collating with the substrate reference mark model 44. This range is a substrate reference mark identification range 42 '.

  When a range 42 ′ that coincides with the substrate reference mark model 44 is detected, the substrate reference mark 40 in the area 42 ′ is detected. The reference mark detection device 21 detects the mark 40 in the registered substrate reference mark area 54 based on the shape and size of the registered mark 40, and uses the coordinates of the center point as position information. Remember.

Also for the partial image 39 ′, the same range 43 ′ as the mask reference mark model 45 is detected by the same procedure, and this is set as the mask reference mark identification range 43 ′, and the mask reference mark 41 in the range 43 ′ is detected. .
That is, the fiducial mark detection device 21 scans an area of the same size as the substrate fiducial mark model 45 at a predetermined resolution in the xy direction of the partial image 39 ′ and detects the same range while collating with the mask fiducial mark model 45.
When a range 43 ′ that coincides with the substrate reference mark model 45 is detected, the mask reference mark 41 in the area 43 ′ is detected. The reference mark detection device 21 detects the mark 41 in the registered substrate reference mark area 54 based on the shape and size of the registered mark 41, and uses the coordinates of the center point as position information. Remember.

The substrate reference mark 40 and the mask reference mark 41 can be set and registered at a plurality of locations on the substrate 1 and the photomask 2. If a plurality of settings are registered, the substrate reference mark 40 and the mask reference mark 41 are registered. The above operation is repeated to detect a plurality of substrate reference marks 40 and mask reference marks 41.
In this embodiment, as described above, alignment is performed at the four positions shown in FIG. 2, and the same processing is performed at the remaining three positions.

When the substrate reference mark 40 and the mask reference mark 41 are detected, the alignment of the substrate 1 and the photomask 2 is executed based on the substrate reference mark 40 and the mask reference mark 41 from these positional relationships. That is, the control device 14 moves the stage 3 in the xy direction and the θ direction by the stage control device 11 and the stage position detection device 12 based on the substrate reference mark 40 and the mask reference mark 41 to align the substrate 1 and the photomask 2. I do.
After the alignment, the exposure light source 5 irradiates exposure light, and the mask pattern 32 is baked on the substrate pattern 31 of the substrate 1 to remove a predetermined portion of the insulating layer.

Next, the overall operation will be described based on the flowcharts of FIGS.
A registration operation using the reference mark registration apparatus 20 will be described with reference to FIG.
A pair of figures at corresponding positions is selected from the figures of the patterns of the substrate 1 and the photomask 2, and these are used as reference marks 40 and 41, and the shape and size are stored (step S1). The imaging device 4 captures the vicinity of the reference marks 40 and 41 to obtain partial images 38 and 39 (step S2), and sets the reference mark models 44 and 45 in the partial images 38 and 39 (step S3). Further, reference mark areas 54 and 55 surrounding the reference marks 40 and 41 in the reference mark models 44 and 45 are set (step S4). These settings and stored contents are registered in the reference mark registration device 20 (step S5).

The operation of the reference mark detection device 21 will be described with reference to FIG.
When the substrate 1 to be exposed is carried onto the stage 3 (step S10), the vicinity of the reference marks 40 and 41 is photographed by the imaging device 4 (step S11), and the registered reference mark models 44 and 45 are displayed. By using this, the same image range is detected as the reference mark identification ranges 42 'and 43' (step S12). The reference mark areas 54 and 55 are detected within the reference mark identification ranges 42 'and 43', and the figure set as the reference marks 40 and 41 is detected (step S13). Alignment is performed using the figure, that is, the reference marks 40 and 41 (step S14), and exposure is performed when the alignment is completed (step S15).
Next, the same operation is repeated for the loaded substrate 1 (step S16).

1: substrate, 2: photomask, 3: stage, 4: imaging device, 5: exposure light source, 6: optical system, 7: optical component, 8: optical component, 9: camera, 10: camera, 11: stage control Device: 12: Stage position detection device, 13: Image processing device, 14: Control device, 15: Display device, 16: Operation device, 17: Display device, 18: Operation device, 19: Imaging device position control device, 20: Reference mark registration device, 21: reference mark detection device, 32: mask pattern, 33: area, 34: area, 37: superimposed image, 38 and 38 ′: partial image, 39 and 39 ′: partial image, 40: substrate Reference mark, 41: Mask reference mark, 42: Area, 42 ': Range, 43: Area, 43': Range, 44: Substrate reference mark model, 45: Mask reference mark model, 48: Blank area, 49: White Area, 54: substrate reference mark zone, 55: mask reference mark region.

Claims (4)

An exposure apparatus for a printed wiring board that exposes a printed wiring board on which a pattern has already been formed using a photomask having a pattern corresponding to the pattern and having a figure at the same position as the figure of the pattern In;
Each of the shape and size of a pair of figures selected from the figures at the same position is stored as a substrate mark and a mask mark for alignment, respectively.
In a partial image of a substrate obtained by imaging the region including the substrate mark, the image is divided by a predetermined area including the substrate mark, and there is no other identical image in the partial image so that it is unique. Store the selected image as a board reference mark model,
Storing the position of the substrate mark in the substrate reference mark model;
It is an image divided by a predetermined area including the mask mark in the partial image of the photomask obtained by photographing the area including the mask mark, and there is no other identical image in the partial image. The selected image is stored as a mask reference mark model,
Storing the position of the mask mark in the mask reference mark model;
A fiducial mark registration device;
In the region including the substrate mark imaged when the printed wiring board and the photomask are aligned, the same image portion as the substrate reference mark model is displayed on the substrate mark based on the substrate reference mark model stored in the reference mark registration device. Detect as the identification range,
Detecting the substrate mark within the detected substrate mark identification range;
Based on the stored mask reference mark model, the same image portion as the mask reference mark model is detected as a mask mark identification range in the area including the mask mark imaged when the printed wiring board and the photomask are aligned. And
A reference mark detection device for detecting the mask mark within the detected mask mark identification range;
Based on the detected substrate mark and mask mark, the printed wiring board and the photomask are aligned, and exposure is performed after the alignment;
An exposure apparatus for a printed wiring board, characterized in that: The substrate reference mark model includes a substrate pattern and a blank portion without the substrate pattern, and the combination of the substrate pattern and the blank portion is the only image without the same image in the partial image. Selected
The mask reference mark model includes a mask pattern and a blank portion without a mask pattern, and a combination of the mask pattern and the blank portion is selected so that there is no other identical image in the partial image and is the only image. Being
The exposure apparatus for a printed wiring board according to claim 1. The predetermined area is rectangular;
The exposure apparatus for a printed wiring board according to claim 1. An exposure method for a printed wiring board, in which a printed wiring board on which a pattern has already been formed is exposed using a photomask having a pattern corresponding to the pattern and having a figure at the same position as the figure of the pattern In
A pair of figures in the same position is selected as a substrate mark and a mask mark for alignment, respectively.
The region including the substrate mark and the region including the mask mark are each photographed with an imaging device to obtain a partial image of the substrate and a partial image of the photomask,
In the partial image of the substrate, an image separated by a predetermined area on the substrate including the substrate mark is stored as a substrate reference mark model,
Storing the position of the substrate mark in the substrate reference mark model;
In the partial image of the mask, an image divided by a predetermined area on the photomask including the mask mark is stored as a mask reference mark model,
Storing the position of the mask mark in the mask reference mark model;
The substrate reference mark model and the mask reference mark model are selected to be unique in the partial image, with no other identical images;
When aligning the printed wiring board and the photomask, each of the area including the substrate mark and the area including the mask mark is imaged with an imaging device,
Based on the stored substrate reference mark model, the same image portion as the substrate reference mark model is detected as a substrate identification range in the imaging field of view,
Detecting the substrate mark within the detected substrate identification range;
Based on the stored mask reference mark model, the same image portion as the mask reference mark model is detected as a mask identification range in the imaging field of view,
Detecting the mask mark within the detected mask identification range;
Based on the detected substrate mark and mask mark, the printed wiring board and photomask are aligned,
Exposure after the alignment,
A printed wiring board exposure method characterized by the above.

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