JPH0232302A - Manufacture of color filter - Google Patents

Abstract

PURPOSE:To execute shift printing and to reduce the cost by forming alignment marks corresponding to the number of each color by a material having large photoabsorptivity in a long wavelength area in which pattern groups of each pattern have large phototransmissivity, respectively. CONSTITUTION:Alignment marks 10R, 20G, etc., corresponding to the number of each color are formed by a material having large photoabsorptivity in a long wavelength area (for instance, 700-800nm) in which pattern groups of each color have large phototransmissivity, respectively, and also, its alignment itself is executed by using a light beam of such a specific long wavelength area. Therefore, what is called shift printing can be executed effectively, and the cost of a color filter can be reduced. Especially, this method can be performed by changing an attached part such as replacing a sensor for an alignment, and can be applied easily to a conventional automatic aligning device, as well.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a technology for manufacturing color filters used in full-color liquid crystal display devices, etc., and more specifically, the invention relates to a technology for manufacturing color filters used in full-color liquid crystal display devices, etc. In particular, so-called shift printing is used to pattern a pattern group of three colors, for example, red, green, and blue, by shifting two photomasks by the pixel pitch for each color. Concerning effective techniques for carrying out the work.

(Prior Art) This type of color filter generally has a group of three color patterns of red, green, and blue that are repeated in the same shape and at the same pitch on one side of a transparent glass substrate, and It has a light-shielding pattern that shields the boundary area of each pattern (pixel) from light.

Conventionally, these three-color pattern groups and the light-shielding pattern are often formed by photolithography technology. In photolithography technology, a number of photomasks is required depending on a pattern or a group of patterns, and four photomasks are usually required to manufacture a color filter.

However, since photomasks are precision components, they are very expensive. Therefore, in the publication of JP-A No. 61-219901, focusing on the fact that the pattern group of three colors has the same shape and is repeated at the same pitch, - photomasks are used for each color by the pixel pitch. A technique has been proposed in which the number of photomasks is reduced by performing printing or exposure in a shifted state, a so-called shift printing technique.

(Problem to be Solved by the Invention) The present inventor became interested in the technique of staggered grilling and
Various considerations were made.

When manufacturing a color filter as described above using the shift printing technique, alignment marks corresponding to each color are formed on at least one of a transparent glass substrate or a photomask for patterning three color patterns. There must be.

In order to more easily align the glass substrate and the photomask, it is preferable to provide three alignment marks corresponding to each color on both the glass substrate and the photomask. Generally, such alignment is performed by first
A two-step process is performed, including a rough alignment process in which the surface alignment marks to be aligned are roughly aligned so that they fall within the same field of view under a microscope, and then a precise alignment process in which both alignment marks are aligned so that they perfectly match. It is done. If both the glass substrate and the photomask have three alignment marks each, rough alignment becomes easier. In particular, when an automatic alignment device is used, the efficiency of such alignment is significantly improved.

Therefore, as shown in FIG. 5(a), depending on the material for forming the light-shielding pattern, each of the cross-shaped alignment marks IOR, IOG, IOB; 10R', IO
G' and IOB' are respectively provided at the upper and lower positions of the glass substrate 12, and correspondingly, cross-shaped alignment marks 20R, 20G, and 20B are also provided on the photomask 22, as shown in FIG. ;20R', 2
Suppose that 0G' and 20B' are provided. In this case, the distance α between the alignment marks on the glass substrate 12 is, for example, 2000 μm, and the distance ′ on the photomask 22 (Q+pixel pitch) is, for example, 2150 μm.

However, as shown in FIG. 6, which shows the state after patterning one color pattern group, for example, a green pattern group, at the same time as the first color pixel is formed, alignment marks 20' of other colors appear as extra marks. The remaining colors may become an obstacle when aligning the next color and subsequent colors. This point is a big problem when using an automatic alignment device. especially,
These problems are noticeable when using a commonly used positive type photoresist.

This invention was made in consideration of the above points,
It is an object of the present invention to provide an improved technique that can effectively apply the technique of staggered grilling, which is advantageous in terms of cost.

(Summary of the Invention) In this invention, three alignment marks corresponding to the number of each color are formed of a material that has a large light absorption property in a long wavelength region in which each pattern group of each color has a large light transmittance, and , the alignment is performed using light in a specific long wavelength range.

As a result, a sensor with high sensitivity in a long wavelength range, for example, 700 μm or more, will be able to detect each group of red, green, and blue patterns, and therefore will not be obstructed by extra alignment marks. The alignment marks can be effectively aligned with each other.

(Example) Fig. 1 shows the spectral characteristics of a typical color filter, in which the horizontal axis shows the wavelength, the vertical axis shows the spectral transmittance, and the curve r drawn with a thick solid line is the red one. The characteristics of the pixel pattern, the characteristics of the pixel pattern where the curve g drawn by the broken line is green,
As can be seen from the curves drawn by thin solid lines, each of which shows the characteristics of the blue pixel pattern, the transmittance of all three colors, red, green, and blue, increases from wavelengths of 650 nm or more.
It becomes quite transparent at wavelengths of 700 nm or more. This is a general tendency when organic dyes or pigments are used as colorants.

On the other hand, the alignment mark that is formed at the same time as the light-shielding pattern is made of the same material as the light-shielding pattern, but many of these materials have light absorption properties even in the long wavelength range of 700 nm or more. For example, polyimides containing metals such as chromium or carbon black, which is an inorganic coloring agent, and furthermore, polyimides containing organic black dyes and near-infrared absorbing pigments that absorb light at wavelengths of 700 nm or more. Polyimide, etc.

Therefore, for example, when observing alignment marks in the long wavelength range of 700 to 800 nm, alignment marks made of the same material as the light shielding pattern and alignment marks on the photomask are recognized as patterns, but they are not transferred during the formation of color pixels. The alignment mark (the above-mentioned alignment mark 20') is not recognized as a pattern.The present invention effectively performs the above-mentioned shift printing by utilizing this principle.

In this invention, basically, the long wavelength range described above may be selected in at least one of the illumination system for alignment or the sensor for alignment. As the sensor, a silicon-based image sensor is suitable. An example of the spectral sensitivity of this sensor is shown in Figure 2.

It has great sensitivity in the long wavelength region of 700 nm or more.

Further, the illumination system can be selected from a wide range of systems that emit light in a long wavelength range. Generally, a white light source such as a halogen lamp is used as a light source, and a filter that cuts visible light is inserted in the middle to increase contrast.

Based on the above idea, a green pattern group was formed using an automatic alignment exposure device using the glass substrate 12 and photomask 22 shown in FIG. It was possible to effectively pattern each red and blue pattern group sequentially in a relatively short time.

In addition to the cross-shaped alignment mark, the first chevron-shaped alignment mark shown in Fig. 3 (a) and (b) can be used.
A combination of a pattern 30 and a second pattern 32, or a combination of a protruding first pattern 40 and a cross-shaped second pattern 42 as shown in FIGS. 4(a) and 4(b). Various methods such as the above can be applied. It is preferable that such alignment marks have a size that can be visually recognized with the naked eye, for example, the size of each mark is about 1 to 2 mm in consideration of rough alignment. Further, each alignment mark corresponding to each color can be formed independently and completely separated from each other as shown in FIG. 5, or by providing continuous portions extending in one direction. It is also possible to form the mark as if it were a single mark as a whole.

Furthermore, some color filters do not have a light-shielding pattern and are composed only of pattern groups of three colors: red, green, and blue. In that case, the alignment mark provided on the glass substrate 12 side can be formed of a metal such as chromium, but it can also be formed of the material of the first color pixel pattern. In this case, only one or two photomasks are required. However, in the latter method, the first color is inside the pixel pattern material.

It is necessary to add an infrared absorbing agent that does not have light absorption in the visible region or at least does not impair the color of the first color. As the infrared absorber to be added, known ones such as benzenedithiol nickel complex and cyanine dye can be used.

Furthermore, it goes without saying that the present invention can be widely applied to the case where color filters of n colors (n is an integer of 2 or more) are manufactured by the shift printing technique.

(Effects of the Invention) According to the present invention, the alignment marks corresponding to the number of each color are formed so that each pattern group of each color has a large light absorption property in a long wavelength range (for example, 700 to 800 nm) that has a large light transmittance. Since the color filters are formed using a material and the alignment itself is performed using light in a specific long wavelength range, so-called staggered printing can be effectively performed and the cost of color filters can be reduced. . In particular, it can be implemented by changing ancillary parts such as replacing sensors for positioning, and can be easily applied to conventional automatic positioning devices.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing spectral characteristics of a color filter, and FIG. 2 is a characteristic diagram showing spectral sensitivity of an image sensor used in the present invention. FIGS. 3 and 4 are diagrams showing other examples of alignment marks, respectively. FIG. 5 is a diagram showing an example of arrangement of alignment marks in staggered printing. FIG. 6 is a diagram for explaining the problem. It is an enlarged view of the main part. 10R, IOG, IOB: 10R', LOG'10
B'... Alignment mark (board side), 12...
Glass substrate, 20R, 200, 20B; 20R',
20G', 20B'... Alignment mark (photomask side), 22... Photomask, 30.40.
...first pattern, 32.42...second pattern.

Claims (1)

[Claims] 1. A method for manufacturing a color filter having a group of patterns repeated in the same shape and at the same pitch on one side of a transparent substrate for a plurality of colors, the method comprising: an alignment mark corresponding to each color is formed on at least one of a photomask for patterning a group of patterns, and the transparent substrate and the photomask are positioned so as to be relatively shifted by the pitch for each color. When aligning, an alignment mark corresponding to each color is formed of a material that has a large light absorption property in a long wavelength range in which each pattern group of each color has a large light transmittance, and the alignment mark is 1. A method for manufacturing a color filter, characterized in that the manufacturing method is performed using light of a wide range. 2. Perform alignment using an automatic alignment device,
A method for manufacturing a color filter according to claim 1. 3. The method for manufacturing a color filter according to claim 1, wherein the color filter has a pattern group of three colors, red, green, and blue, as well as a light-shielding pattern that blocks light from a boundary area of each pattern in each pattern group. 4. The method for manufacturing a color filter according to claim 1, wherein the alignment mark corresponding to each color is present on both the transparent substrate and the photomask. 5. The color filter according to claim 3, wherein after forming the light-shielding pattern, pattern groups of three colors are sequentially formed, and when forming the light-shielding pattern, alignment marks corresponding to each color are also formed using the forming material. . 6. The method for manufacturing a color filter according to claim 1, wherein the light in the long wavelength range has a wavelength of 700 nm or more. 7. The method for manufacturing a color filter according to claim 6, wherein the alignment is performed using transmitted light of 700 nm or more and a sensor having high sensitivity at 700 nm or more.