JPH0545514A - Formation of multilayered interference pattern - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to form a flat final surface with few defects on the surface of the multilayer interference film. [Structure] First, a vacuum deposition film (2) of SiO ₂ is formed on a glass substrate (1). Next, after forming the resist pattern (3a), the multilayer interference film having the maximum film thickness is changed to the minimum film thickness (here, the third color blue transmission filter is used) so that the surface of the completed color filter shown in FIG. The SiO ₂ vapor-deposited film is anisotropically etched by dry etching by a film thickness obtained by subtracting (film thickness). As shown in FIG. 3, a green low-temperature vapor deposition layer 1.94 μm (4), which serves as a green transmission filter as a first-color multilayer interference filter, is formed solid. The non-formation portion of the first color green transmission filter pattern is lifted off by a resist as shown in FIG. The above steps are repeated for each of the second and third colors to form a color filter having a flat surface as shown in FIG.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pattern of a multilayer interference film on a substrate, especially a thin film pattern such as a color separation filter pattern.

[0002]

2. Description of the Related Art Conventionally, in the field of image pickup devices such as image pickup tubes and solid-state image pickup devices, color separation filters have been used as a means for multicoloring the image pickup device. As the color separation filter, an organic type by dyeing a resin and an inorganic type by a multilayer interference film are mainly put into practical use. Although the latter tends to have a higher manufacturing cost than the former, it has high transmittance characteristics and is also excellent in environmental resistance characteristics such as weather resistance and light resistance.

On the other hand, in various image pickup devices, as the definition of the required image becomes higher, the demand for higher definition of the device itself and further, the definition of the color separation filter used therefor increases. There is a demand for miniaturization of the pixel pattern size of the color separation filter used.

Inorganic type color separation filters have been conventionally manufactured by a lift-off method, and the main reason for this is that etching of a multilayer interference film has been an obstacle to production. As a commonly used lift material, a metal such as Cu is generally used in consideration of easiness of film formation, patterning and lift-off, and suitability for a heating process at the time of film formation of a multilayer interference film. However, as the color separation filters become finer as described above, it is difficult to obtain practical performance in terms of shape and defect frequency with the lift-off method of the metal lift material that indirectly determines the pattern shape. It's coming.

Forming the lift material with resin rather than metal was not considered. As a cause of this, it is common that the resin is once formed on the entire surface by a spin coater or the like and then subjected to post-exposure development to form a pattern, but if unevenness exists on the surface,
The unevenness may cause uneven coating during spin coating, which may make uniform coating difficult.

There is also a technique of forming a similar color separation filter by a corrosion (wet etching) method. However, in that case, first, a solid multilayer interference film to be a color separation filter is formed on the entire surface of the substrate, and a resist is formed on the pattern forming portion of the multilayer interference film. Then
Using the etchant that dissolves and removes the multilayer interference film, remove the multilayer interference film in the part where the resist is not placed, that is, the pattern formation part, and then use the etchant that dissolves and removes the resist, and This is the most orthodox method to obtain the pattern of the color separation filter by removing the resist that is formed on the film.However, when removing only one of the overlapping films, the normal method is used. There are many problems such as etching of other films among the overlapping films.

Particularly in the case of a color separation filter, as a post-process after pattern formation, SiO ₂ thick film coating → polishing protective coat → polishing → polishing protective coat peeling → SiO ₂ thick film coating again in the SiO ₂ protection process. It is required to create a coat. In this process, the irregularities and steps of the filter cause defects in the product.

[0008]

In the conventional metal lift material, the problem of miniaturization due to isotropic etching, which is a feature of wet etching, and the multilayer interference film (0.1-5.
The problem of thickening the film required to lift off (0 μm), defects caused by a long lift-off time, problems of controlling film defects / foreign matter / adhesion, liquid management such as liquid fatigue, and surface irregularities as the process progresses It is desired to solve various problems such as dealing with the above.

A resist without dry etching or plasma treatment has a small problem such as the metal lift material described above, but has a problem with resist pattern resistance in vacuum deposition of a multilayer interference film. Due to peeling or the like due to insufficient adhesive force, a shape defect, adhesion of a multilayer interference film to a resist pattern forming portion, so-called color mixture defect or partial defect defect is generated. Further, if the adhesive force is too large, problems such as long lift-off time and generation of resist residue have occurred.

In the pattern forming method by the corrosion method, when the adhesion between the multilayer interference film and the substrate or the resist is poor, the etching solution permeates between them and the patterning accuracy is significantly lowered. Further, since wet etching is isotropic etching, it is also reduced by undercutting.

Particularly when the interference film is a color separation filter, the color separation filter formed earlier is exposed to an etching solution or a resist developing solution anew each time the color separation filter is formed later, and thus the color separation filter is formed first. The color separation filter is more likely to be damaged by the etching solution or the resist developing solution.

As a post-treatment process after the pattern formation of the color separation filter, a light-resistant, weather-resistant and water-resistant protective film (mainly S
(iO ₂ etc.) is required together with the role of protecting the surface of scratches and stains, preventing spectral shift due to moisture at visible long wavelengths, and preventing the leak phenomenon when incorporated in an image pickup tube. The surface irregularities, especially the products having a large step difference of 5000 angstroms or more, become more prominent. In addition, cracks at the time of forming the protective film, Newton's rings on the pixels, or partial stains or overlapping of pattern edge portions may cause the filter surface to appear rough, especially in oblique light, which may be caused by a step. There are various defects. These various problems are phenomena that appear prominently in a fine pattern on the order of several μm or less.

[0013]

In order to solve the above problems, the present invention provides a method for forming a pattern of a multilayer interference film on a substrate, in which a SiO ₂ film is first vacuum-deposited and then a pattern non-forming portion is formed. Then, the resist is patterned, and dry etching is performed up to the multilayer interference film thickness. A method for forming a multilayer interference film pattern is characterized in that a multilayer interference film is vacuum-deposited on the entire surface, and then a desired pattern is repeated twice or more by a lift-off method.

The vapor-deposited layer of the multi-layer interference film is a known ordinary vapor-deposited layer,
It can be formed by alternately stacking a large number of high-refractive index layers and low-refractive index layers having a predetermined film thickness by a vapor deposition method such as sputtering vapor deposition, but it is formed by a low temperature vapor deposition method in which the vapor deposition temperature is about 150 ° C. Preferably. As a result, it is possible to reduce the influence on the occurrence of defects in the resist pattern as compared with the normal vapor deposition method in which the vapor deposition temperature is about 300 ° C.

Further, in the film formed by irradiating the ions by forming the multilayer interference film by the ion assisted deposition, the weakly bonded portions are sputtered or the surface is compacted by the energy of the ions. As a result, the packing density of the film can be increased, and as a result, it is possible to improve characteristics such as temporal change due to spectral shift due to hardness, strength, humidity, residual stress, and a film having a high refractive index can be formed at a low temperature.

Furthermore, in the low temperature ion assisted vapor deposition, the synergistic effects of the low temperature vapor deposition and the ion assisted vapor deposition described above can be expected.

[0017]

By using the above forming method, the surface is finally flattened.

As a result, the resist can be supplied by the spin coating method even if the surface shape becomes complicated, such as the irregularities and grooves on the surface as the multilayer interference pattern is generated one after another. Unlike the metal film formed by coating, there is no rough portion of the film quality such as cracks or the like formed on the side wall of the pattern, and there is no weak portion locally and it is uniform. Moreover, the surface after coating is flat and does not hinder the formation of a resist pattern in the next step.

[0019]

EXAMPLES The present invention will be specifically described below based on examples.

1 to 12 show a green transmission filter,
The manufacturing steps in the case of manufacturing a color filter in which three types of color separation filter patterns of a red transmission filter and a blue transmission filter are two-dimensionally arranged on a glass substrate by the method for forming a multilayer interference pattern of the present invention are shown in order. There is.

That is, in this method, first, a vacuum deposition film (2) of SiO ₂ is applied on the glass substrate (1). At this time, a better multilayer film quality can be obtained by using the ion gun and the neutralizer together. Ar + 10% O ₂ was used as the ionization gas for the conditions of the ion gun.
Acceleration voltage 0.5KV, acceleration current 60m at SCCM flow rate
A is vapor-deposited.

After that, the non-formation portion of the first color multilayer interference filter pattern is resist-patterned to form a resist pattern (3a) as shown in FIG. In this case, as the resist used for the resist pattern (3a),
It has a high resolution, a relatively high viscosity and is capable of thick film,
It is preferable to use a heat-resistant positive resist that has a stable shape and can be suitably used even during dry etching or plasma treatment (including RIE). For example, FH5600F (manufactured by Fuji Hunt) that can withstand heating up to about 130 ° C.
Can be used and is applied and patterned by a spin coating method to obtain a resist pattern (3a) having a film thickness of 4.3 μm.

After the resist pattern (3a) is formed, the multilayer interference film having the maximum film thickness is used in advance so that the surface of the finished color filter shown in FIG. The SiO ₂ vapor-deposited film is anisotropically etched by dry etching by a film thickness obtained by subtracting (filter film thickness). At this time, the glass substrate can function as a stopper layer for dry etching.

In the process shown in FIG. 2, the glass substrate is dry-etched, but SiO ₂ may remain thick as a base. Resist pattern (3a ')
The shape stability such as heat resistance can be further improved by the process up to FIG. 2 at the same time, and the large etching selection ratio with respect to the resist is shown in FIG. 3 to FIG. 4, FIG. 7 to FIG. This greatly affects the ease of lift-off in each step from 11 to FIG. This relationship is shown in FIG.
It depends on the etching rate as shown in.

Next, a green low-temperature vapor-deposited layer as a green transmission filter as a first-color multilayer interference filter was 1.94 μm.
The m (4) is solidly formed as shown in FIG.

Then, the non-formation portion of the first color green transmission filter pattern is lifted off by a resist as shown in FIG. Specifically, for example, Microposit Remover 1165 (manufactured by Shipley) may be used, and if the multilayer film and the resist remain on the substrate, the liquid temperature may be raised to about 80 ° C., a solvent or US Washing may be used together.

Then, a resist pattern (3b) as shown in FIG. 5 is obtained in a portion where the second color red transmission filter pattern is not formed in the same manner as in the case of forming FIG. If the color separation filters of the three colors have the same pixel size, the patterning accuracy of the resist is the same as in the first step of forming FIG. 1 and is not difficult. The resist does not cause various problems even if the process is advanced and the shape is complicated in that the unevenness of the surface, the rough portion of the film formed on the side wall of the pattern, and cracks do not occur as seen in the metal lift material.

Then, as shown in FIG. 6, in the same manner as in FIG.
The substrate is etched by the film thickness of the red transmission filter of the color. At the same time, a resist pattern (3b ') having improved shape stability such as adhesion and heat resistance is obtained.

Then, as shown in FIG. 7, a red low temperature vapor deposition layer 1.53 μm (5) to be a second color red transmission filter is formed in a solid manner by the same method as in FIG.

Then, as shown in FIG. 8, the red-light-transmitting filter pattern non-forming portion is lifted off by a resist in the same manner as in FIG.

Similarly, as shown in FIG. 9, a resist pattern (3c) is formed on the non-formed portion of the third color blue transmission filter pattern.

Next, in the step shown in FIG. 10, the plasma resistance using Ar gas is merely required to improve the resist resistance and dry etching is not particularly required. Further, when the substrate is dry-etched by the film thickness of the blue transmission filter pattern of the third color in the process of FIG. 10, it is dry-etched by each film thickness in the process of FIGS.

Then, as shown in FIG. 11, a low temperature blue vapor deposition layer of 1.08 μm serving as a blue transmission filter for the third color.
(6) is solidly formed, and finally, as shown in FIG.
The resist pattern (3c ') lifts off the non-formed portion of the blue transmission filter pattern. As a result, three color separation filters are obtained.

The embodiment of the present invention has been described above, but the present invention is not limited to this and can take various forms. For example, in the above example,
The multilayer interference film to be formed was three types of low temperature vapor deposition layers of green, red and blue, but any multilayer interference film can be used as long as it is two or more types. Further, the pattern shape thereof may be various ones including those in which stripe filters are formed in parallel. As for the substrate, a silicon wafer or CCD may be used directly as the substrate, or an on-chip for directly forming a color filter on the uneven surface of the device may be used as the substrate.

[0035]

According to the present invention, since the accuracy of the resist pattern determines the pattern size of the color separation filter, it is possible to sufficiently meet the demand for miniaturization of the pattern size due to the high definition of the required pixel size. Also, thick film is possible, the lift-off time is short, and the damage caused by the drug can be reduced.
Patterning is possible regardless of the surface shape. The process is easy by repeating SiO ₂ vapor deposition (first time only), resist patterning, dry etching, film deposition, and lift-off, and the yield can be significantly improved. Therefore, it is possible to form the precise multilayer interference pattern directly on the solid-state image sensor and manufacture it advantageously even when the surface has irregularities.

Even if the substrate is a glass substrate,
Since a selection ratio during dry etching with a resist cannot be obtained, it is easy to deposit several μ by depositing a SiO ₂ film on the base.
With a fine pattern of m or less, it is possible to preliminarily flatten the surface by etching in advance in accordance with the film thickness of the next step with respect to multiple types of multilayer interference patterns having different thicknesses. It is possible to prevent the generation of cracks, which is a cause of uneven streaks, during vacuum deposition of the overcoat that protects the multilayer interference pattern from the external environment.

Further, in order to eliminate the unevenness of the surface, it is not necessary to increase the overcoat film thickness and repeat the flattening process by polishing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view in the process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view in the process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view in the process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view in the process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view in the process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view in the process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view in the process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 8 is a cross-sectional view in the process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 9 is a cross-sectional view in the process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 11 is a cross-sectional view showing the process of forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 12 is a cross-sectional view after forming a multilayer interference pattern according to an embodiment of the present invention.

FIG. 13 is a graph showing the relationship between dry etching and pressure.

[Explanation of symbols]

1 glass substrate 2 SiO ₂ film 3a, 3b, 3c resist pattern 3a ', 3b', 3c 'resist pattern after dry etching 4 green low temperature deposition layer 5 red low temperature deposition layer 6 blue low temperature deposition layer

Claims (7)

[Claims] 1. A method for forming a pattern of a multilayer interference film on a substrate, comprising the following steps (1), (2) and (3) in order. (1) A SiO ₂ film is vacuum-deposited on a substrate. (2) patterning a resist on the pattern non-formation part,
The SiO ₂ film is dry-etched up to the maximum multilayer dry film thickness, the multilayer interference film is vacuum-deposited on the entire surface, and then the resist film is removed by lift-off method to form a desired pattern of the multilayer interference film. (3) The step (2) is repeated once or more. 2. The method for forming a multilayer interference film pattern according to claim 1, wherein the multilayer interference film is formed by low temperature vapor deposition. 3. The method for forming a multilayer interference film pattern according to claim 1, wherein the resist is a heat-resistant positive resist. 4. The method for forming a multilayer interference film pattern according to claim 1, wherein the multilayer interference film is formed by ion-assisted vapor deposition. 5. The method for forming a multilayer interference film pattern according to claim 1, wherein the multilayer interference film is formed by low temperature ion assisted deposition. 6. The method for forming a multilayer interference film pattern according to claim 1, wherein the substrate is a transparent substrate, and the multilayer interference film is a color separation multilayer interference film. 7. The method for forming a multilayer interference film pattern according to claim 1, wherein the substrate is a solid-state image sensor, and the multilayer interference film is a color separation multilayer interference film.