JP2007256880A - Photomask correcting method, photomask, exposure method, and aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily obtain higher resolution of an exposure pattern with an inexpensive proximity exposure type aligner without using an expensive projection exposure type aligner. <P>SOLUTION: An opening part or light shield part of a photomask is provided with a light shield pattern or opening pattern as a correction pattern 15 along its circumference. Consequently, a pattern finally formed on a substrate by pulling on right-angled vertexes of the outer periphery of the opening part or light shield part 14a of the photomask and the correction pattern has small distortion and is in a shape having small corner roundness, i.e. a small R value. Consequently, the photomask can easily be corrected and the resolution of the exposure pattern can be made high. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates generally to an exposure process related to the field of photolithography electronics, and more particularly to a patterning printing exposure process in manufacturing a color filter.

In general, a color filter for a liquid crystal panel is an optical element having a fine black, red, green, blue pattern or the like. The manufacturing method includes a printing method, a transfer electrophotographic method, an ink jet method and the like, and a general method includes a method using a photolithography technique (hereinafter referred to as a photolithography method). In this photolithography method, the substrate is baked by a step of applying a photosensitive resist or the like on a substrate such as glass, an exposure step, a development step of removing an unnecessary pattern portion of the resist from the exposed substrate, an oven, a hot plate, or the like. Thus, the process includes each step such as a firing step for expressing necessary physical properties such as light resistance, solvent resistance, heat resistance, and adhesion strength required for a product having a necessary pattern.
In addition, a color filter including a plurality of dyes is completed by sequentially repeating the same steps for each color.

  Here, the exposure process described above is a negative type or positive type in which a desired pattern is drawn at an opening / light-shielding part on a substrate or the like coated with a resist containing a photosensitive agent or the like that is a substrate to be exposed. It is a process of curing a desired pattern by irradiating an electromagnetic wave of a certain wavelength range such as ultraviolet rays or an electron beam through a photomask, and it is important to influence the pattern shape in the photolithographic method as well as the development process. It is a difficult process. A high-quality color filter can be created by accurately exposing and developing a desired pattern in these steps.

The exposure methods are roughly classified into a proximity exposure method and a projection exposure method.
The proximity exposure method is also called a proximity exposure method, and both are techniques widely used in the photolithography method.
In the proximity exposure method, a photomask pattern is formed by irradiating parallel light in a state where a predetermined gap is provided between a photomask provided with an opening and a light shielding portion and a substrate with respect to a desired pattern. This is a method of transferring to a substrate. In particular, the color filter manufacturing process is a general technique remarkably widespread, and its principle is simple.

  However, one of the disadvantages of the proximity exposure method is light diffraction / interference during transmission of parallel light through a photomask. In the corner portion or the like in the photomask pattern, the light intensity tends to blur at the boundary between the opening and the light shielding portion due to the diffraction and interference of the light. Therefore, the rounded pattern on the substrate is resolved at the corner portion, and as a result, the desired pattern cannot be exposed and developed with high accuracy. In particular, when a complicated shape having many corners or the like is desired for a pattern, there is a problem that it is very difficult to create a high-quality color filter, and this is a problem to be solved.

This problem can be avoided to some extent by extremely reducing the gap between the photomask and the substrate.
However, in order to ensure the quality of the product, it is necessary to make the extremely shortened gap uniform with high precision within the photomask surface, and fine adjustment is indispensable for that purpose. The adjustment requires a very advanced technique.

  Furthermore, if foreign matter adheres to the glass substrate for some reason in the coating process, which is the previous step, the foreign matter on the substrate becomes a photomask by extremely reducing the gap between the photomask and the substrate. The gap between the photomask and the substrate is drastically reduced because there is a possibility that defects will occur in the product due to the adhesion and the exposure process performed through them, resulting in a significant reduction in product quality. That is not the preferred method.

  On the other hand, the projection exposure method is a principle and method in which a lens or mirror is provided between the photomask and the glass substrate, and the pattern drawn on the photomask is imaged on the substrate. Therefore, the resolution is very high. Also, in the projection exposure method, the distance between the photomask and the substrate is sufficiently large, so there is no risk of foreign matter adhering to the photomask as in the proximity exposure method, and there is a risk of causing defects in the product. No.

However, the projection exposure apparatus usually has a problem that the optical system is complicated due to its structure and the initial cost is several times as high as that of the proximity exposure method.
Therefore, when new equipment is introduced, the initial investment cost is an important factor as well as the running cost. Therefore, it can be said that it is desirable in terms of profit to shift the exposure apparatus from the proximity exposure method to the projection exposure method. Absent.
Therefore, as described above, high definition, which is one of the problems in the proximity exposure method, is strongly desired.

As a method for realizing high accuracy in the proximity exposure method, improvement of an optical system such as a light source and a lens, improvement of a material such as a photosensitive agent, correction of a photomask and the like are considered.
For example, photomask correction is a method of giving an auxiliary pattern to a photomask pattern and forcibly resolving a desired pattern on a substrate, and is generally used as an OPC in the semiconductor field. It is a technique. (Patent Document 1 JP2001-100309)

  On the other hand, in the field of color filters, a photomask correction method, an exposure method, and an exposure apparatus that provide an auxiliary pattern to a corner portion of a photomask pattern are proposed as photomask adjustment methods.

  However, in the conventional photomask correction method, the exposure method, and the exposure apparatus described above, the correction patterns are likely to be complicated, and it is difficult to design a photomask having the correction patterns. Therefore, it is possible to easily create a photomask. There was a problem that it was not possible.

  Accordingly, the present invention provides a photomask correction method and a photo for easily realizing high-resolution exposure patterns using an inexpensive proximity exposure type exposure machine without using an expensive projection exposure type exposure machine. An object is to provide a mask, an exposure method, and an exposure apparatus.

  In order to achieve the above-described object, a photomask correction method of the present invention is a photomask correction method used for a proximity exposure method, wherein the opening is formed in an opening formed as a mask pattern of the photomask. A light-shielding correction pattern is provided along the outer light-shielding portion. The photomask correction method of the present invention is a photomask correction method used in a proximity exposure method, and is provided along an opening portion on the outer periphery of the light shielding portion in a light shielding portion formed as a mask pattern of the photomask. An opening correction pattern is provided.

  The photomask of the present invention is a photomask used for a proximity exposure method, wherein a light-shielding correction pattern along a light-shielding portion on the outer periphery of the opening is provided in an opening formed as a mask pattern. And The photomask of the present invention is a method for correcting a photomask used in the proximity exposure method, and an opening correction pattern is provided along the outer periphery of the light shielding portion in the light shielding portion formed as a mask pattern. It is characterized by that.

  The exposure method of the present invention is an exposure method in which exposure is performed by a proximity exposure method, and a light-shielding correction pattern along a light-shielding portion on the outer periphery of the opening is provided in an opening formed as a mask pattern of a photomask. It is characterized by that. The exposure method of the present invention is an exposure method in which exposure is performed by a proximity exposure method, wherein an opening correction pattern is provided along the opening portion on the outer periphery of the light shielding portion in the light shielding portion formed as a mask pattern. Features.

  The exposure apparatus of the present invention is an exposure apparatus that performs exposure by a proximity exposure method, and provides a light-shielding correction pattern along a light-shielding portion on the outer periphery of the opening in an opening formed as a mask pattern of a photomask. It is characterized by that. The exposure apparatus according to the present invention is an exposure apparatus that performs exposure by a proximity exposure method, wherein an opening correction pattern is provided along an opening portion on an outer periphery of the light shielding portion in a light shielding portion formed as a mask pattern. Features.

According to the present invention, a correction light-shielding portion or opening is provided in a photomask used in an exposure process while using an inexpensive proximity exposure type exposure machine without using an expensive projection exposure type exposure machine. Thus, the photomask can be easily corrected.
As a result, high resolution of the exposure pattern can be realized, so that even if the desired pattern has a complicated shape and has many corners, a high-quality product can be easily manufactured. .

Embodiments of a photomask correction method, a photomask, an exposure method, and an exposure apparatus according to the present invention will be described below with reference to FIGS.
FIG. 1 is a schematic block diagram of a proximity exposure apparatus used in an exposure method according to an embodiment of the present invention.
As shown in the figure, the proximity exposure apparatus of this example is configured to include an exposure light source lamp 1, an elliptical mirror 2, a cold mirror 3, a filter 4, an integrator lens 5, a collimation mirror 6, a reflection mirror 7, and a mask 8. Yes.
Light from the exposure light source lamp 1 is reflected by the cold mirror 3 through the elliptical mirror 2, passed through the filter 4, integrator lens 5, collimation mirror 6, reflection mirror 7 mask 8, and on the glass substrate (exposed substrate) 10. The coated photosensitive agent 9 is exposed.

Although it does not specifically limit about the light source lamp 1, The thing between a space | interval is small and becomes a point light source as much as possible is desirable. This is because when the gap is widened due to the effect of increasing the output or the like, the intensity of the normal distribution becomes broad and the energy loss in the integrator lens 5 increases.
It should be noted that the improvement in resolution, which is the subject of the present invention, also depends greatly on the optical system. Therefore, it is desirable that the distribution of the bright line of the light source lamp, the material of the mirror system thereof, and the collimation half angle due to the shape and size of the integrator lens are also performed under appropriate conditions.
As described above, the gap between the photomask and the substrate coated with the photosensitive agent should be exposed at a gap of 50 μm or more, preferably about 200 μm, in order to prevent foreign matters from entering.

  FIG. 2 shows a typical rectangular pattern. Reference numeral 11 denotes a square opening pattern drawn on a photomask assuming about 30 μm. This shape has a total of four 90 degree corners 12a to c, and no correction is applied.

FIG. 3 shows a pattern 13 obtained when a negative photosensitive material is exposed using the photomask pattern of FIG. Unlike the photomask pattern 11, the pattern 13 has a shape in which four corners are rounded and protruded, and conversely, a side portion is recessed and distorted.
This is because the intensity increases due to light interference at the corner. Since the rectangle of the pattern 11 has four corners, there are four portions with high light intensity. As a result, the base of the pattern is resolved, so that a distorted pattern such as the pattern 13 is obtained. Become.
This phenomenon is not limited to the square of the pattern 11, but occurs in all corners from an acute angle to an obtuse angle, and the tendency is particularly prominent in a shape having an acute angle corner such as a triangle.

FIG. 4 shows a negative photomask pattern 14 having a light shielding correction pattern 15 in the opening. Reference numerals 16 a to 16 d denote corner portions of the photomask pattern 14.
The pattern 14 has a square opening 14a similar to the opening shown in FIG. 2, and a correction light shielding pattern 15 is provided in the opening 14a along the outer light shielding portion 14b. . The light shielding correction pattern 15 is formed over the entire circumference including the corner portion of the opening 14a, and is formed in a rectangular loop shape.
By providing such a correction pattern 15, light or the like having a level of intensity that is not actually resolved is generated in the corner portion. As a result, a pattern finally formed on the substrate in such a manner that the outer periphery and the vertex of the right angle portion of the correction pattern are pulled together has a small distortion, such as a pattern 30 shown in FIG. A shape with a small R value can be obtained.

FIG. 5 shows a method of applying a correction pattern 18 to a negative photomask 17 having a complicated shape in which convex and concave corners are combined. Reference numerals 19a, 19b, and 19c denote corner portions of the photomask pattern 17, and 19d and 19e denote corner portions of the correction pattern 18.
In the corner portion 19b, when there is no correction pattern, the intensity of light is greatly increased at the corner portion having an acute angle, so that the resolved shape is greatly swelled and rounded. If a correction pattern as shown in FIG. 5 is applied, light having an intensity that is not actually resolved is generated even in the corner portion 19e, and the corners are finally rounded in such a manner that they are pulled together. A small pattern shape can be obtained on the substrate.
Further, in the corner portion 19a, the light intensity increases slightly in the absence of the correction pattern, and the shape to be resolved becomes a gently sloping line. However, if the correction pattern is applied, the corner portion 19d However, in the case where light of an intensity that is not actually resolved is generated and these are pulled together, a pattern shape in which corner roundness is finally suppressed can be obtained on the substrate.
In the straight line portion, the intermediate position is substantially resolved on the substrate in such a way that slightly intense light generated at the end portion and light having an intensity that is not actually resolved generated by the correction pattern are attracted to each other.
As described above, even if the shape is complicated, by applying a correction pattern, it is possible to resolve a shape on the substrate with a small distortion and a small corner roundness.

There is no particular problem even if the correction pattern is non-continuous except for the corner portion. FIG. 6 is a continuous example, and FIG. 7 is a non-continuous example. In FIG. 6, a continuous correction pattern 21 is formed on a negative photomask pattern 20 having a complicated shape. Further, in FIG. 7, a discontinuous correction pattern 23 is formed on a complex-shaped negative photomask pattern 22.
That is, when the correction pattern is used, even if the photomask has a complicated shape as shown in FIGS. 6 and 7, it is only necessary to simply apply the correction pattern along the outer periphery. A correction pattern can be easily created for the photomask pattern.

  There is an appropriate value for the line width of the correction pattern. The line width that is actually resolved varies depending on the sensitivity of the resist used, the wavelength range of the light source, conditions such as illuminance, etc., but when a color filter resist is used, the line width generally exceeds 8 μm. There is a risk of actual resolution. Further, in order to exhibit the correction effect, a line width of 0.5 μm or more is necessary. Furthermore, since the image is resolved on the substrate from the middle of the outer periphery of the correction pattern and the light shielding portion, the distance between the correction pattern and the outer periphery must be constant, and is preferably 0.5 μm or more.

4 to 7, the light shielding correction pattern is provided in the opening as the mask pattern. Conversely, the opening correction pattern may be provided in the light shielding part as the mask pattern.
4 to 7 assume that a negative photomask using a negative resist is used, but conversely, when a positive photomask is used, the outer periphery of the light shielding portion or the opening including the corner portion in the opening is opened. An opening correction pattern or a light shielding correction pattern may be provided along the portion. In any case, the line width may be 0.5 μm or more and 8 μm or less as described above.

Examples will be described below.
The exposure optical system is the general one shown in FIG. 1, and the lamp is 2 kW. The collimation half angle was fixed at 2 °.
As shown in FIG. 7, a light-shielding correction pattern is provided along the light-shielding portion for the opening pattern having a complicated shape. The line width was 2.0 μm. The distance between the correction pattern and the outer periphery was constant and 2 μm.
After confirming the substrate after the development process and baking process, the pattern R finally formed on the substrate has a minimal R, and almost no shape distortion is observed, ensuring the required pattern shape of the color filter. I was able to.
(Comparative Example 1)

Except not using the correction pattern, negative exposure was performed in the same manner as in Example 1 to form the pattern 31 shown in FIG.
And after passing through a development process and a baking process, when the substrate was confirmed, the shape of the corner portion of the pattern finally formed on the substrate was rounded, and the quality of Example 1 could not be reached. It was.
(Comparative Example 2)

  Negative exposure was performed in the same manner as in Example 1 except that the line width of the correction pattern was 10 μm. Then, after the development process and the baking process, the substrate was confirmed. As a result, the correction pattern portion was not exposed, and as a result, a pattern with a desired shape could not be formed on the substrate.

It is a schematic block diagram of the proximity exposure apparatus used with the exposure method by embodiment of this invention. It is a top view which shows an example of a negative photomask pattern without correction | amendment. It is a top view which shows the pattern shape resolved when exposed with the negative photomask pattern without correction shown in FIG. It is a top view which shows an example of the negative photomask pattern which provided the correction pattern by embodiment of this invention. It is a top view which shows an example of the complicated shape negative photomask pattern which provided the correction pattern by embodiment of this invention. It is a top view which shows an example of the negative photomask pattern of the complicated shape which provided the continuous correction pattern by embodiment of this invention. It is a top view which shows an example of the negative shaped photomask pattern of the complicated shape which provided the discontinuous correction pattern by embodiment of this invention. It is a top view which shows an example of the pattern finally formed on a board | substrate with the negative photomask shown in FIG. It is explanatory drawing which shows an example of the negative photomask pattern of the same complicated shape as FIG. 7 without correction | amendment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Exposure light source lamp, 2 ... Ellipse mirror, 3 ... Cold mirror, 4 ... Filter, 5 ... Integrator lens, 6 ... Collimation mirror, 7 ... Reflection mirror, 8 ... Mask, 9 ... Photosensitive agent, 10 ... glass substrate.

Claims (16)

A photomask correction method used for the proximity exposure method,
In the opening formed as a mask pattern of the photomask, a light-shielding correction pattern along the light-shielding portion on the outer periphery of the opening is provided.
A photomask correction method characterized by the above.   2. The photomask correction method according to claim 1, wherein a line width of the light shielding correction pattern is a constant width, and the line width is not less than 0.5 μm and not more than 8 μm. A photomask correction method used for the proximity exposure method,
In the light shielding part formed as a mask pattern of the photomask, an opening correction pattern was provided along the outer periphery of the light shielding part.
A photomask correction method characterized by the above.   4. The photomask correction method according to claim 3, wherein a line width of the opening correction pattern is a constant width and the line width is not less than 0.5 μm and not more than 8 μm. A photomask used in the proximity exposure method,
In the opening formed as a mask pattern, a light-shielding correction pattern was provided along the light-shielding portion on the outer periphery of the opening.
A photomask characterized by that.   6. The photomask according to claim 5, wherein a line width of the light shielding correction pattern is a constant width, and the line width is not less than 0.5 μm and not more than 8 μm. A photomask correction method used for the proximity exposure method,
In the light shielding part formed as a mask pattern, an opening correction pattern is provided along the outer periphery of the light shielding part.
A photomask characterized by that.   8. The photomask according to claim 7, wherein a line width of the opening correction pattern is a constant width, and the line width is not less than 0.5 μm and not more than 8 μm. An exposure method for performing exposure by a proximity exposure method,
In the opening formed as the mask pattern of the photomask, a light-shielding correction pattern along the light-shielding part on the outer periphery of the opening was provided.
An exposure method characterized by the above.   The exposure method according to claim 9, wherein a line width of the light-shielding correction pattern is a constant width, and the line width is not less than 0.5 μm and not more than 8 μm. An exposure method for performing exposure by a proximity exposure method,
In the light shielding part formed as a mask pattern, an opening correction pattern is provided along the outer periphery of the light shielding part.
An exposure method characterized by the above.   12. The exposure method according to claim 11, wherein a line width of the opening correction pattern is a constant width, and the line width is not less than 0.5 μm and not more than 8 μm. An exposure apparatus that performs exposure by a proximity exposure method,
In the opening formed as the mask pattern of the photomask, a light-shielding correction pattern along the light-shielding part on the outer periphery of the opening was provided.
An exposure apparatus characterized by that.   14. The exposure apparatus according to claim 13, wherein a line width of the light shielding correction pattern is a constant width, and the line width is not less than 0.5 μm and not more than 8 μm. An exposure apparatus that performs exposure by a proximity exposure method,
In the light shielding part formed as a mask pattern, an opening correction pattern is provided along the outer periphery of the light shielding part.
An exposure apparatus characterized by that. 16. The exposure apparatus according to claim 15, wherein the opening correction pattern has a constant line width, and the line width is not less than 0.5 μm and not more than 8 μm.

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