JPH0745080Y2 - Exposure mask for black stripe formation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an exposure mask for forming a black stripe used for forming a black stripe on a display surface of an image display device by a photolithography method.

[Conventional technology]

As an image display device such as a liquid crystal display panel, there is one in which a black stripe is formed on a display surface in order to make a displayed image clear.

This black stripe is generally formed by depositing a metal film such as chrome or the like, which will become the black stripe, on the surface where the black stripe is formed (for example, the glass substrate surface of the liquid crystal display panel), and then applying a photoresist thereon to apply this photoresist. An exposure process is performed using an exposure mask having a predetermined pattern,
Next, after this photoresist is developed, the metal film is etched by using this photoresist as a mask, and the metal film is patterned into a black stripe pattern by a photolithography method.

By the way, in the case of forming a black mask by the photolithography method, if the area of the black stripe forming surface is small, the entire photoresist applied on the black mask can be exposed at one time, but as in a large-screen image display device. If the area of the black stripe formation surface is large,
Due to the size of the exposure device, the entire photoresist applied on the black stripe forming surface cannot be exposed at one time. In this case, therefore, the exposure process of the photoresist is divided into a plurality of times. .

FIG. 5 shows a divided exposure method in which the exposure process of the photoresist is performed in plural times. Here, an example in which the exposure process is performed in four times is shown. In FIG. 5, reference numeral 1 denotes a substrate on which a black stripe is formed (for example, a glass substrate of a liquid crystal display panel), and a metal film 2 to be a black stripe is formed on the entire surface of the substrate 1, and a metal film 2 is formed thereon. Photoresist 3 is applied. This exposure processing method is a method in which the black stripe forming surface (the surface of the substrate 1) is divided into four regions A, B, C and D, and the photoresist 3 in each of the regions A, B, C and D is exposed in order. And the exposure process for one area, for example area A, is
This region A is aligned with the exposure mask 10 in the exposure device so as to face it, and the photoresist 3 in this region A is exposed through the exposure mask 10. At this time, the other areas B, C, D are outside the light irradiation range, and the areas B, C, D are not exposed to light. This is the same in the exposure processing of the other areas B, C and D.

Incidentally, the development processing of the photoresist 3 is performed in all areas A, B,
It is performed after the C and D exposure processes.

Conventionally, an exposure mask as shown in FIG. 6 has been used for forming the black stripes by the photolithography method.

This exposure mask is formed by forming a large number of mask lines 12 on the surface of a transparent substrate 11 made of glass or a resin film at a pitch corresponding to the intervals of black stripes formed on the display surface of an image display device. The line 12 is linearly formed over the entire length thereof. Note that a negative photoresist is generally used for photolithography, and in the exposure mask used for photolithography using this negative photoresist, the mask line
12 is formed of an opaque film made of metal or the like, and a portion between each mask line 12 is a light transmitting portion. Further, FIG. 6 shows an exposure mask for forming a grid-like black stripe, and the mask line 12 is formed in the horizontal direction and the vertical direction.

[Problems to be solved by the device]

However, since the conventional exposure mask shown in FIG. 6 has the mask line 12 formed in a straight line over the entire length, the exposure process of the photoresist is performed by the divided exposure shown in FIG. If there is an error in the alignment accuracy of the exposure area, the formed black stripes are displaced at the boundaries of the exposure areas, and the screen of the image display device appears to be displaced at the boundaries.

That is, FIG. 7 shows the photoresist exposure state at the first exposure time and the second exposure time when the negative type photoresist was subjected to the exposure processing by the division exposure, and the photoresist pattern after the development processing. 7 (a) shows a state in which the first exposure (exposure of the area A shown in FIG. 5) has been completed, and a shows a non-exposed portion corresponding to the mask line 12 of the exposure mask. Further, FIG. 7 (b) shows a state in which after the first exposure, the next exposure region (region B shown in FIG. 5) is exposed to the exposure mask and b
Indicates a non-exposed portion corresponding to the mask line 12 of the exposure mask. In the divided exposure, in order to prevent the black stripe from breaking, the exposure mask is made slightly larger than the area of the exposure region so that the edges of the first exposure range and the second exposure range are overlapped, and this overlap region d is used. Is double-exposed (hereinafter, this lap area d is referred to as a double-exposure area). In this case, there is an error in the alignment accuracy of the exposure region with respect to the exposure mask in either the first exposure or the second exposure, and the non-exposed portion a in the first exposure and the non-exposed portion b in the second exposure Figure (b)
As shown in FIG. 7, the pattern of the photoresist 3 which has been subjected to the division exposure and then subjected to the development process is displaced in the width direction with the double-exposure region d as a boundary, as shown in FIG. It becomes a pattern. Further, as shown in FIG. 7 (b), when the non-exposed portion a in the first exposure and the non-exposed portion b in the second exposure are displaced in the width direction, both sides of the double exposure area d (in the figure, (Dashed line hatched)
a'and b'are exposed during either the first or second exposure. That is, the a'portion not exposed in the first exposure is exposed in the second exposure, and the b'portion not exposed in the second exposure is exposed in the first exposure. Therefore, the developed photoresist 3 has a pattern in which the width of the double exposure region d is narrowed. Note that, in FIGS. 7B and 7C, the widthwise deviation between the non-exposed portion a in the first exposure and the non-exposed portion b in the second exposure is exaggeratedly shown. Amount of deviation in the width direction of the non-exposed portions a and b (positioning error with respect to the exposure mask)
Is about 2 μm to 3 μm at the maximum.

Since the metal film to be the black stripe is patterned by etching using the developed photoresist 3 as a mask, the black stripe is formed in the same pattern as the developed photoresist 3.

FIG. 8 shows the pattern of the black stripes 13 formed when the negative photoresist is divided and exposed using the conventional exposure mask, and there is an error in the alignment accuracy of each exposure area during the divided exposure of the photoresist. As a result, the formed black stripes 13 become a pattern in which the double exposure region d is deviated in the width direction and the width of the double exposure region d is narrowed as shown in the figure.

The amount of deviation of the black stripe 13 in the widthwise direction in the double exposure area d is, as described above, 2 μm at maximum.
It is about 3 μm, and this deviation is 13
Is extremely small compared to the width (about 20 μm).

However, the conventional exposure mask, as shown in FIG.
Since the mask line 12 is formed in a straight line over the entire length thereof, the formed black stripe 13 has straight lines on both sides sandwiching the double exposure area d as shown in FIG. The deviation of the stripe 13 in the double exposure area d is noticeable. The deviation of the black stripes 13 in the double exposure area d occurs in all the black stripes 13 arranged in parallel, so that the left half and the right half of the screen are affected by the deviation of the black stripes 13. It looks like it's shifted up and down. This is a linear black stripe 13
The same is true for the case where there is a shift in the double exposure area, and in this case, the upper half and the lower half of the screen appear to shift left and right.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to eliminate the error in the alignment accuracy of each exposure area when the exposure processing of the photoresist is performed by the divided exposure. By forming the black stripes in a pattern in which the deviation in the width direction in the double exposure area is inconspicuous, it is possible to prevent the screen from appearing to be misaligned due to the deviation in the double exposure area. It is to provide an exposure mask for stripe formation.

[Means for Solving the Problems]

The black stripe forming exposure mask of the present invention comprises a large number of mask lines formed on the surface of a transparent substrate at a pitch corresponding to the intervals of the black stripes, and the mask lines are formed such that the short straight line portion is in the longitudinal direction. , And each of the straight line portions is formed in a pattern shifted in the mask line width direction alternately.

[Action]

According to the black stripe forming exposure mask of the present invention, the mask line is formed in a pattern in which short straight line portions are continuous in the lengthwise direction and the straight line portions are alternately displaced in the mask line width direction. Therefore, the black stripes formed by the photolithography method using this exposure mask have a pattern in which the entire length is alternately shifted in the width direction at short intervals. Therefore, even if the formed black stripe is displaced in the width direction in the double exposure area due to an error in the alignment accuracy of each exposure area when the exposure processing of the photoresist is performed by the divided exposure, the total length of the black stripe is short. Since the widths alternate with each other in the width direction, the deviation in the double exposure region is not noticeable.

Therefore, according to the exposure mask of the present invention, even if there is an error in the alignment accuracy of each exposure region when the exposure process of the photoresist is performed by the divided exposure, the black stripe is displaced in the width direction in the double exposure region. Can be formed in an inconspicuous pattern to prevent the screen from appearing to be misaligned due to misalignment in the double-exposure region of the black stripe, thus improving the appearance of the screen.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4 of an exposure mask used when forming a black mask by a photolithography method using a negative photoresist.

FIG. 1 shows a part of the exposure mask of this embodiment.

This exposure mask is one in which a large number of mask lines 22 are formed at a pitch corresponding to the intervals of black stripes formed on the display surface of an image display device on the surface of a transparent substrate 21 made of glass or a resin film. The line 22 is formed of an opaque film made of metal or the like, and the portion between each mask line 22 is a light transmitting portion. The exposure mask of this embodiment is
The mask lines 22 are for forming a lattice-shaped black stripe, and are formed in the horizontal direction and the vertical direction. Each mask line 22 has a short straight line portion 22.
a is continuous in the lengthwise direction, and the respective straight line portions 22a are formed in a pattern that is alternately displaced in the mask linewidth direction.
Further, the boundary portion 22b between the straight line portions 22a, the width of the straight line portion 22a
The width is smaller than the width of
One side edge of b is linearly continuous with one side edge of the linear portion 22a to which one end thereof is connected, and the other side edge of the boundary portion 22b is linearly continuous with the other side edge of the linear portion 22a to which the other end is connected. ing. In the figure, the deviation of each straight line portion 22a of the mask line 22 is exaggeratedly shown, but the amount of deviation of each straight line portion 22a in the mask line width direction is determined by dividing exposure of the photoresist by division exposure. It is set to about 1/2 (about 1 μm to 1.5 μm) of the maximum error (about 2 μm to 3 μm) in the alignment accuracy of each exposure region. The width of each straight portion 22a is about 20 μm.
The width of the boundary portion 22b is about 1.9 μm to 2.85 μm, and the length thereof is a lap region at the edge portion between the first exposure range and the second exposure range when the photoresist is divided and exposed, that is, the seventh area. The length of the double exposure area d shown in FIG.
70 μm) and the length is almost the same. Further, in this embodiment, the length of each straight line portion 22a of the mask line 22 is set to the mask line 2
2 and a length that is shorter than the arrangement pitch of the mask lines 22 in the direction orthogonal to 2 by the length of the boundary portion 22b, and intersect each straight line portion 22a in the middle with the mask line 22 in the orthogonal direction. There is. Also, each mask line 22 is 1
Every other book is formed in the same pattern, and the mask lines 22 between them are formed in a pattern in which the adjacent mask lines 22 are inverted in the width direction.

Thus, according to the exposure mask of this embodiment, the mask line 22 has a pattern in which the short straight line portions 22a are continuous in the length direction and the straight line portions 22a are alternately displaced in the mask line width direction. Since the black stripes are formed by the photolithography method using this exposure mask, the black stripes have a pattern in which the entire length is shifted in the width direction alternately at short intervals.

Therefore, if a black stripe is formed by the photolithography method using this exposure mask, the formed black stripe is duplicated due to the error in the alignment accuracy of each exposure region when the exposure process of the photoresist is performed by the divided exposure. Even if the black stripes are shifted in the widthwise direction in the double exposure area, the total length of the black stripes is alternately shifted in the widthwise direction at short intervals, so that the shifts in the double exposure area are not conspicuous. The screen can be prevented from appearing shifted and the appearance of the screen can be improved.

That is, FIGS. 2 to 4 show the patterns of the black stripes 23 formed when the negative type photoresist is divided and exposed using the exposure mask of the above-described embodiment, and FIG. A pattern when the left black stripe 23 is displaced upward from the exposure area d, a pattern when the left black stripe 23 is displaced downward from the exposure area d, and a pattern when the left black stripe 23 is displaced from the exposure area d in FIG. It shows the pattern when there is no.

As described above, the black stripes 23 formed by using the exposure mask of the above-described embodiment have a pattern in which the entire length is alternately shifted in the width direction at short intervals. Therefore, even if the black stripe 23 shifts in the widthwise direction in the double exposure area d as shown in FIG. 2 or 3, due to an error in the alignment accuracy of each exposure area in the division exposure, this double exposure Since the deviation in the area d is not conspicuous at all because of the shape of the entire black stripe, the screen does not appear misaligned in the double exposure area d. Further, if there is no error in the alignment of the exposure areas during the divided exposure, the black stripes 23 on the left and right are not displaced as shown in FIG. 4, so the screen appears to be displaced in the double exposure area d. There is no such thing. Further, in this case, the double exposure area d of the black stripe 23 and the linear portions 22a on both sides thereof are linearly connected, but the length of this linear portion is about twice that of one linear portion 22a. ,
This straight part is not noticeable.

In the above embodiment, the length of each straight line portion 22a of the mask line 22 is defined by the boundary portion 22b from the arrangement pitch of the orthogonal mask lines 22.
The length is shortened by the length of
The length of a is twice the arrangement pitch of the orthogonal mask lines 22.
The length may be arbitrary as long as it does not exceed about three times, or the lengths of the linear portions 22a may be different from each other. The point is that the pattern of the mask line 22 has a short width over its entire length. It suffices that they are alternately offset in the direction. Further, in the above-mentioned embodiment, although every other mask line 22 is formed in the same pattern, all the mask lines 22 may be formed in the same pattern, or each mask line 22 may be formed. The pattern may be changed randomly.

Further, although the exposure mask for the negative photoresist has been described in the above embodiment, the present invention can also be applied to the exposure mask for the positive photoresist. In that case, the mask line is a transparent portion, and The area between the mask lines may be opaque. In addition, when a positive photoresist is used, if there is an error in the alignment accuracy of each exposure area during divided exposure, the width of the double exposure area of the formed black stripe becomes wider, so that the positive photoresist is used. In the case of a resist exposure mask, the width of the boundary between the straight lines of the mask line may be made larger than the width of the straight lines.

Further, the present invention is not limited to the grid-shaped black stripes, and can be applied to an exposure mask for forming black stripes in only one direction.

[Effect of device]

According to the black stripe forming exposure mask of the present invention, due to an error in the alignment accuracy of each exposure area when the exposure processing of the photoresist is performed by the divided exposure, the formed black stripe is widthwise in the double exposure area. Even if the black stripes are displaced, the total lengths of the black stripes are alternately formed in the width direction at short intervals, so that the deviations in the double-exposure region are not conspicuous. Therefore, the formed black stripes cause the screen to appear displaced. You can prevent things and improve the appearance of the screen.

[Brief description of drawings]

FIG. 1 is a plan view of a part of an exposure mask showing an embodiment of the present invention, and FIGS. 2 to 4 are formed when the negative type photoresist is divided and exposed using the exposure mask of FIG. FIG. 5 is a pattern diagram of a black stripe, FIG. 5 is a diagram showing a divided exposure method in which a photoresist exposure process is divided into a plurality of times, and FIG. 6 is a plan view of a part of a conventional exposure mask.
FIG. 7 is a diagram showing a photoresist exposure state at the time of the first exposure and the second exposure when the negative type photoresist is subjected to the exposure process by the division exposure, and FIG. 8 is a diagram showing the pattern of the photoresist after the development process. It is a pattern diagram of a black stripe formed when a negative photoresist is divided and exposed using a conventional exposure mask. 21 ... Transparent base material, 22 ... Mask line, 22a ... Straight part, 22b ... Border part, 23 ... Black stripe, d ... Double exposure area.

Claims (1)

[Scope of utility model registration request] 1. An exposure mask used for forming a black stripe on a display surface of an image display device by a photolithography method, wherein a large number of mask lines are formed on a transparent substrate surface at a pitch corresponding to the interval between the black stripes. Black stripe formation, characterized in that the mask lines are formed in a pattern in which short straight line portions are continuous in the lengthwise direction and the straight line portions are alternately displaced in the mask line width direction. Exposure mask.