JPH01200302A - Manufacture of color separation filter - Google Patents

Abstract

PURPOSE:To arrange respective color filter patterns on a substrate while maintaining high size accuracy and alignment accuracy by lifting off a 3rd color filter on etching prevention films while leaving 1st and 2nd color filters protected by the etching prevention films. CONSTITUTION:The 1st etching prevention film 5 is formed on the surface of the 1st color filter 2 on the substrate, the 2nd etching prevention film 8 is formed on the surface of the 2nd color filter 6, and etching is carried out. The 3rd color filter 9 is formed thereupon and the etching prevention films 5 and 8 are dissolved to lift off the 3rd color filter 9. Consequently, the 1st color filter 2 and 3rd color filter 9 and a 4th color filter consisting of the overlap part of the 1st color filter 2 and 2nd color filter 6 are arranged on the substrate 1 while the high size accuracy and alignment accuracy are maintained.

Description

[Detailed description of the invention] (Industrial field of application) The present invention relates to a method for manufacturing a color filter,
In particular, the present invention relates to a method of manufacturing a color separation filter for a color image sensor.

[Conventional technology]

In a color image sensor such as a single-tube color image sensor tube or a single-plate color solid-state image sensor, several kinds of sensors are used in front of the photoelectric conversion unit for the purpose of converting the color information contained in the image formed on the imaging surface into an electrical signal. A color separation filter is provided in which color filters having different spectral transmittances are regularly arranged in a stripe shape or a mosaic shape. This color separation filter divides the image formed on its surface into minute parts using regularly arranged color filters, and photoelectrically converts the color information in each part in the form of the intensity of light that passes through each color filter. It has the function of conveying information to the department.

For this reason, in image recognition using a color image sensor,
The quality of the recognized image, ie, the resolution, color reproducibility, etc., varies greatly depending on the characteristics of the color separation filter used. On the other hand, with the spread of home VTRs and small portable VTRs, there is an increasing demand for smaller color image sensors, and color There is an increasing demand for higher performance of image sensors. The demand for smaller size and higher performance of color imaging devices is due to the reduction of electron beam scanning size and improvement of carrier frequency in the case of single-tube color image pickup tubes, and the demand for smaller size and higher performance in the case of single-chip color solid-state image pickup devices. This is achieved by reducing the chip area, improving the element characteristics itself, examining the light reception accumulation mode, and further miniaturizing the pixels.The color separation filter used has a smaller pattern size, improved dimensional accuracy, and one end of the filter. There is a need to improve the shape of the

As described above, the characteristics of color separation filters for color image pickup devices are closely related to the imaging characteristics of color image pickup devices, and therefore, many studies have been made to date on the structure and manufacturing method thereof. Methods for manufacturing color separation filters for color imaging elements that are currently widely used can be classified into the following three types from the viewpoint of methods for forming color filter patterns on substrates.

(1) A method of obtaining color filter patterns by patterning a dyeable substance on a substrate in advance and then dyeing it.

(2) After patterning and forming a substance (called a lift material) on a substrate that can be removed later by dissolution etc., a color filter layer is formed on the substrate, and then the lift material is formed by removing the lift material. How to get the color filter to be removed in other areas.

(3) After forming a color filter layer on the substrate in advance and then providing a patterned mask layer on the surface of the color filter layer,
A method of etching to leave the color filter only in the area protected by the mask layer, and then removing the mask layer to obtain a color filter blank.

[Problem to be solved by the invention]

Problems encountered when these methods are used to manufacture color separation filters will be described below.

The method (1) is the so-called relief staining method. In the relief dyeing method, it is difficult to achieve both dyeability and patternability because the dyeable material itself has patterning properties, and it is difficult to achieve high pattern accuracy due to pattern swelling that occurs during dyeing. It has been extremely difficult to form a fine pattern of several micrometers or less with good properties.

The method (2) is the so-called lift-off method. In the lift-off method, the edges of the color filter break are formed by cracks that occur in the color filter layer that covers the edges of the lift material, so it is difficult to control the shape of the edges, and it is difficult to obtain the desired edge shape. requires a detailed study of lift-off conditions. In addition, if the color filter cracking becomes several micrometers or less, it is necessary to form a color filter layer so as to uniformly fill the inside of the groove of several micrometers or less sandwiched between the lift materials. Formation of the layer is extremely difficult in practice.

Method (3) is a method of forming a pattern by directly etching the color filter. In this method, a fine and highly accurate mask pattern can be formed by using a photolithography method for patterning the mask layer, and by using reactive ion etching etc. as an etching method, etching processing that is faithful to the mask pattern can be performed. Since this is possible, in principle it is possible to obtain a fine color filter pattern of 1 μm or less.

In this way, the method of forming color firkupakun is (
Method 3) has the best microfabriability.

However, since color separation filters are formed by regularly arranging two or three color filter patterns on a substrate, no matter which method (1), (2), or (3) is used, It was necessary to repeat the formation of color filter particles on the substrate two to three times. Therefore, if a color filter pattern has already been formed under or near the area where the second or third color filter pattern is to be formed, the effect of irregularities on the substrate surface or changes in reflectance in the vicinity The problem has been that it is difficult to maintain the thickness, dimensions, etc. of the color filter pattern formed thereon to be the same as when forming it on a smooth substrate. To address these problems, attempts have been made to reduce the effects of the irregularities and reflectance of the underlying material by placing a flattening layer on each color filter pattern. However, when introducing a flattening layer, it is necessary to design the color filter pattern on the assumption that the flattening layer will be introduced, and the optical consistency between the color filter pattern and the flattening layer must be considered. This has the disadvantage that the degree of freedom in designing the filter pattern is limited. Furthermore, when the size of the color filter pattern becomes several μm or less, the ratio between the thickness of the color filter pattern (approximately II!m) and the pattern dimension, that is, the aspect ratio, increases, so a flattening layer is further provided for each color filter. In some cases, the thickness of the filter layer of the finally formed color separation filter may be larger than the pattern size. In such a case, since the image projected onto the photoelectric conversion unit changes depending on the direction of incidence of the incident light at the boundary between the color separation filters, it becomes difficult to maintain uniform and good characteristics of the color separation filter. Furthermore, even if the problems mentioned above are resolved,
In a color separation filter, each color filter pattern must be arranged without any gaps and in such a way that their positional relationship is uniform within the filter surface. Problems have arisen in that it is difficult to maintain high alignment accuracy between each color filter pattern, and it is also difficult to maintain uniform alignment between each sample.

The above-mentioned problems regarding the manufacturing method of color separation filters for color imaging elements are unavoidable as long as the process of sequentially forming filter strips of each color is adopted, but until now, these problems have not been solved. No new manufacturing method has been discovered.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems regarding the method of manufacturing color separation filters for color imaging elements, and to provide a method for arranging filter patterns of each color on a substrate while maintaining high dimensional accuracy and alignment accuracy.

[Specific means to solve the problem]

In order to achieve the above-mentioned object, the present invention has made intensive studies on the manufacturing method of color separation filters, and as a result, three types of color filters that selectively transmit light in a specific wavelength range are arranged on a substrate in a desired pattern. In the method for manufacturing a color separation filter formed by
forming a first anti-etching film on the surface of the color filter corresponding to an area where the color filter is to be disposed; forming a second color filter; A step of forming a second anti-etching film on the surface of the second color filter corresponding to the area where the filter is to be placed, and an etching process to separate the second color filter and the first color filter. The first color filter that is successively removed and protected by the first etching prevention film, the second color filter that is protected by the second etching prevention film, and the color filter below the first color filter that is protected by the first etching prevention film. leaving the first color filter on the substrate, and dissolving the first and second etching preventive films after forming the third color filter; Through a step of lifting off the third color filter on the prevention film, the first color filter, the third color filter, and the overlapping portion of the first color filter and the second color filter are obtained. It has been found that it is possible to G-mi-device a fourth color filter on a substrate while maintaining high dimensional accuracy and alignment accuracy.

[Detailed description and operation of the invention] In the present invention, a first color and a second color having mutually different spectral transmittances are used.
A color filter of the first color among the color filters of the color, and a color filter of the first color.
Creation of a color separation filter formed by arranging a fourth color filter obtained from the overlapping portion of a color filter and a second color filter, and a third color filter in a desired pattern on a substrate. At this time, the color filter pattern of the first color and the color filter pattern of the fourth color obtained from the overlapping part of the color filters of the first color and the second color are transferred between the layers of the color filters of the first color and the second color. The first feature is that the etching prevention films provided on the surfaces of the two color filters are formed by one etching process using them as masks. According to this method, the areas to be left after patterning the first color filter and the fourth color filter are the etching mask formed on the surface of the first color filter and the surface of the second color filter, respectively. Since it is determined by the formed etching mask, the dimensional accuracy of each color filter pattern and the alignment accuracy between each filter pattern are determined by the patterning accuracy of each etching mask.

The patterning accuracy of the etching mask can be suppressed to ±0.2 μm or less in size and alignment by using photolithography. Furthermore, when an etching mask is formed on the surface of the second color filter, the etching mask formed on the surface of the first color filter causes undulations on the surface of the second color filter, but the thickness of the etching mask is Since the thickness can be set to 0.2 μm or less, the influence of these undulations on patterning accuracy can be ignored.

Further, as the etching method, preferably an anisotropic etching method such as reactive ion etching (hereinafter abbreviated as RIE) is used, thereby making it possible to perform an etching process in which the difference in pattern conversion is almost zero. Furthermore, the area that will ultimately be left as a color filter is protected by the etching mask until it is removed after etching.
Color filters are less likely to deteriorate during the manufacturing process. The second feature of the present invention is that after patterning the first color filter and the fourth color filter, a third color filter layer is formed while leaving the etching mask, and then the etching mask is dissolved. By removing and lifting off the third color filter layer on the etching mask, a third color filter layer is formed in the area where the first color filter and the fourth color filter are not present. be. As mentioned earlier, in the lift-off method, the edges of the color filter pattern are formed by cracks that occur in the color filter layer that covers the vicinity of the edges of the lift material. Moreover, the better the coverage of the color filter layer, the more difficult it becomes to control the pattern shape after lift-off. However, on the other hand, if the shape of the edge cross section of the lift material pattern is vertical or overhanging, and the color filter layer can be formed only in the vertical direction with respect to the substrate, the cross-sectional shape of the color filter bag after lift-off can be formed close to vertical. It is also possible to do so. In the present invention, if RIE is used for etching the color filters of the first and fourth colors, the shape of the edge cross section of the color filter pads of the first and fourth colors can be made vertical, and the surface of the color filter pads can be made vertical. If an etching mask is used as a lift material and a third color filter layer is formed by an anisotropic film formation method such as vacuum evaporation, the slope of the edge cross section of the third color filter pattern formed after lift-off can be made steeper. , found that it can be made steeper. The third color filter pattern formed in this way is positioned by the first color filter pattern and the fourth color filter pattern that have been formed in advance. There is no variation in the positional relationship near the boundary between the color filter patterns of the first color and the fourth color. As described above, according to the present invention, it is possible to easily form a color separation filter in which the pattern size and alignment errors of each color filter are suppressed to ±0.2 μm or less. Furthermore, the present invention basically ensures that the etching selectivity with respect to the color filter layer can be maintained no matter what kind of material is used for the color filter layer.
Further, it can be applied if an etching mask that can be used as a lift material is used and a color filter layer formed by a lift-off method can be formed with controlled anisotropy. - For example, when a metal oxide such as an optical multilayer film made of TiOl-SiOl is used as a color filter layer and RIE using a halogenated hydrocarbon such as ChCIz is used as an etching method, it can be used as an etching mask and lift material. By using aluminum, chromium, copper, etc., it is possible to form a color separation filter with fine and highly accurate color filter separation.

Embodiments of the present invention will be specifically described below with reference to FIG.

[Example] A TiO2-3iOz alternating multilayer film (thickness Q, 9 cm) was deposited on a transparent substrate 1 made of Vilex glass (manufactured by Corning, USA) with a thickness of 0.5 mm and a diameter of 3 inches.
A cyan filter layer 2 consisting of a Cr film 3 (thickness 0.15 μm) is formed on its surface by sputtering.
l11) was formed. A positive photoresist 51400-2 was applied to the surface of this Cr film by photolithography.
7 (For forming a mask pattern 4 made of Cr made by Sible Far East Co., Ltd., see FIG. 1(a)), Cr other than the mask pattern 4 was covered with a ceric ammonium nitrate-perchloric acid based etching solution. After removing the film 3 by etching, the mask pattern 4 is dissolved and removed using a remover 140 (manufactured by Sible Far East Co., Ltd.).
An etching mask 5 (first etching prevention film) consisting of r1fl was obtained (see FIG. 1(b)). Next, a TiO□-5ing alternating multilayer film (film thickness 0.7 μm) was formed by vacuum evaporation method.
An etching mask 7 (second etching prevention film) made of a Cr film was formed on the surface of the yellow filter layer 6 in the same manner as in the formation of the etching mask 5 (see Fig. 1(c)). )reference).

Next, the cyan filter layer 2 and the yellow filter N6 outside the areas protected by the etching masks 5 and 8 were removed by RIH (see FIG. 1(d)). As the etching gas, cp and c+ are used, and the gas flow is ff.
By performing etching for about 30 minutes at i50sec, gas pressure of 20mmTorr, and applied power density of 0.33W/cffl, it was possible to obtain an etching mask that was faithful to the pattern dimensions of etching masks 5 and 7 and whose etched cross-sectional shape was perpendicular. . Then, by vacuum evaporation method, T
After forming a red filter layer 8 consisting of an iOAr5ift alternating multilayer film (film thickness 1.3 μm) (see Figure 1(e)), CrIII was removed by dipping it in a ceric ammonium nitrate-perchloric acid etching solution. The etching masks 5 and 7 consisting of the above etching masks 5 and 7 were dissolved and removed, and the red filter layer 8 placed on the etching masks 5 and 7 was lifted off (see FIG. 1 Cf).

Through the above steps, it was possible to obtain a color separation filter for a color image sensor, which was constructed by arranging cyan, green, and red color filter patterns in a stripe shape with a line width of 3 μm and a pinch size of 9 μm.

(Effects of the Invention) According to the present invention, three color filters can be formed by one etching process and one lift-off, and the etching masks corresponding to each color filter can be formed with high dimensional accuracy and alignment accuracy. It can be kept and formed. Therefore, compared to the conventional method, the patterning accuracy of the color filter can be greatly improved and the manufacturing process can be shortened.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(f) are explanatory diagrams showing an example of the method for manufacturing a color separation filter of the present invention in the order of steps. 1. Glass substrate 2, cyan filter layer 3, C film 4, mask pattern 5.7. Etching mask 6, yellow filter layer 8, red filter layer

Claims (3)

[Claims] (1) In a method of manufacturing a color separation filter formed by arranging three types of color filters that selectively transmit light in a specific wavelength range on a substrate in a desired pattern, a first color filter is formed on the substrate. forming a first etching prevention film on the surface of the color filter corresponding to the area where the color filter is to be disposed;
forming a second anti-etching film on the surface of the second color filter corresponding to the area where the second color filter is to be disposed; The two color filters and the first color filter are successively removed, and the first color filter is protected by the first etching prevention film and the second color filter is protected by the second etching prevention film. a step of leaving the second color filter and the front first color filter below it on the substrate; and after forming the third color filter, removing the first and second etching prevention films. The third color filters on the first and second etching prevention films are lifted off by dissolving the first and third color filters, and the first color and A method for manufacturing a color separation filter, characterized in that color filters of a fourth color obtained from the overlapping portions of the color filters of the second color are respectively arranged on a substrate in a desired pattern. (2) The color according to claim 1, wherein the means for sequentially etching the second color filter and the first color filter is an anisotropic etching method such as reactive ion etching. Method for manufacturing a decomposition filter. (3) The method for manufacturing a color separation filter according to claim 1 or 2, wherein the means for forming the third color color filter layer is an anisotropic film formation method such as vacuum evaporation.