JPS59178416A - Production of color filter - Google Patents

Abstract

PURPOSE:To form a fine color filter having high accuracy with ease in a way as to be advantageous in mass production by subjecting the filter to a stage for a surface treatment with gaseous plasma prior to the dyeing of a patterned layer. CONSTITUTION:Casein contg. dichromate is coated to about 1mum thickness on a silicon substrate on which 0.5mum Al is preliminarily deposited by evaporation. Said casein is exposed through a photomask by a contact exposing system and is developed by water. The pattern is treated with oxygen plasma (standard condition of 150W and 0.5Torr) and thereafter the patterned layer is dyed with an acidic cyan dye. A pattern resolution and dyeability are improved by the plasma treatment of the patterned layer and the formation of the fine color filter having high accuracy is made possible; moreover, the mass productivity is improved.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a method for forming a color filter.

More specifically, the present invention relates to an improvement in the process of forming a high-definition color filter on a solid-state image sensor.

[Technical background of the invention and its problems]

Conventionally, as a method for forming a color filter on a solid-state image sensor, the color filter is placed on a photosensitive resin that can be dyed, exposed and developed to form a pattern in the entire desired dyeing area, and then the patterned area is coated with various dyes. A so-called "staining method" is known in which the entire filter is formed in one layer. Although this method is an extremely simple method, it is possible to form a color filter that fully satisfies the current required characteristics, and it is also a method that is lower in cost and more suitable for mass production than other methods. The process of forming a filter using such a dyeing method is generally carried out through the following steps. That is, a transparent smoothing layer is provided on the solid-state image sensor, and a dyeable photosensitive layer is coated on this layer by a spin-coating method, and the desired area of the photosensitive layer is exposed to light through a photomask, and then a desired pattern is formed. is imaged by development. (At this stage, the baking process has been completed and the dye-receiving layer has been formed.) The baking layer, that is, the dye-receiving layer, is treated and dyed using an appropriately selected dye solution and dyeing conditions. Zero coloring is performed. This process is repeated two or three times to form two or three color filter layers. Usually, a colorless and transparent intermediate protective layer is often provided between the layers to prevent color mixing between the colored layers. In this way, in the dyeing method, patterning and dyeing are sequentially applied to the same resin layer, so the resin layer has excellent pattern forming ability as well as dyeing performance that shows good spectral characteristics. In addition, you need to be 11 years old. Up until now, in the color filter construction process, proteins such as polyvinylfluor, gelatin, etc. have been used exclusively as photosensitive agents for patterning and dyeing layers. These materials are
Although it is a very good dye-receptive system, when viewed as a light-sensitive material, it belongs to a negative-type light-sensitive material.
However, the pattern resolution is not necessarily good.

Recently, solid-state image sensors have become smaller, have higher performance, and have a high 1i"J
As the demand for KAIJ continues to increase, the pattern size of color filter pixels tends to become even finer from the current approximately 10 to 20 μm, while at the same time improving filter quality with fewer defects and improving pitch alignment. In order to respond to the trend toward improving the uniformity of spectral characteristics, etc., in the color filter forming process using negative photosensitive materials, improvements to the conventional filter forming process such as fine pattern formation and double-sided dyeing are required. (This is a challenge for mass production of high-definition color filters.)

[Purpose of the invention]

The present invention is a method for forming color filters by the conventional dyeing method of patterning and dyeing using a negative photosensitive material. The present invention provides an improved filter forming process.

[Summary of the invention]

The method of the present invention is a color filter characterized in that, after a pattern formation step of a negative-tone material such as gelatin containing chromate having excellent dyeing properties and casein, the patterned layer is treated in a plasma atmosphere. This is the manufacturing method. That is, the present invention provides a method for forming a color filter on a solid-state imaging device, including a step of providing a negative red light layer on a smoothed solid-state imaging element and subjecting it to % exposure and development treatment to form a pattern; A method for producing a color filter, comprising a step of surface-treating the patterned layer with a plasma gas containing at least one component such as oxygen, nitrogen, air, etc. between the step of dyeing the entire patterned layer. It is.

The non-invention under μ will be explained in more detail.

As mentioned above, the photosensitive resin layer used to form the color filter is classified as a negative type material, and the pattern resolution of these materials depends not only on the material composition (but also on various other factors). For example, the type of exposure device, type of underlying substrate, presence or absence of substrate steps, development conditions, baking conditions, etc.In addition to these factors, the film thickness of the pattern forming material itself is influenced by the resolution. It is known that negative-tone materials undergo a pattern formation process that involves crosslinking, resulting in a film thickness of 0, nonuniform exposure intensity distribution, and swelling during development. In addition, due to the low r value, the streaking at the edge of the pattern becomes extremely large, which often worsens the pattern conversion difference.For this reason, in order to obtain high resolution in pattern formation, it is necessary to use as much film as possible. Thick/thin (preferably).

However, the color filter forming process is unique compared to the resist treatment process used in the manufacturing process of semiconductor integrated circuits, etc., in that after forming the coating, desired molecules are poured and the pattern area is dyed as shown. The goal is to do the following. Even with materials that have excellent dyeing properties, such as gelatin and casein, which are used in the current color filter manufacturing process.

In order to obtain predetermined spectral characteristics, it is necessary to provide a thickness of at least 1 to 2 μm. At such a film thickness, the resolution exhibited by the above material is at most 10μ, considering the dimensional uniformity.
It is only around m. Of course, it is possible to increase the dyeability of the material layer (or to make the pattern forming layer as thin as possible by devising dyeing conditions (e.g., increasing the dyeing temperature9, adding dyeing aids, etc.), but it is possible to Problems arise such as it is difficult to obtain a single layer of dyeing solution in a short time and storage management of the dyeing solution becomes difficult.

The inventors of the present invention have conducted extensive studies to solve all of these problems, and as a result, the above-mentioned method that satisfies the requirements of high-resolution patterning and obtaining all the desired spectral characteristics by performing plasma processing. This led to the discovery of an inventive method.

This will be explained in detail using the following drawings.

All-aluminum 0.3 μm thick aluminum containing dichromium V salt, which is a photosensitive material, was prepared in various film thicknesses on a silicon substrate that had been evaporated with nitrogen in advance, and a photomask was fabricated using a contact exposure method. exposed to light and developed with water,
At this time, the light intensity was selected to correspond to a residual film rate of 80 on the characteristic curve.

The resolution was defined as the minimum pattern width in which the lines and spaces were equally spaced, and the relationship with the film thickness was investigated. After that, the same pattern was treated with oxygen plasma (standard conditions: 150 W, 0.15 Torr) for 5 minutes, and the same dimensions were measured and the relationship with the film thickness was investigated. 4μ
m was decreasing. ) In Figure 1, the 11% thick solid line (1) is
This is the casein for casein that is not subjected to plasma treatment, and the dotted area (
2) is the pattern resolution when plasma processing is performed.

On the other hand, a casein pattern was formed on a glass substrate in the same manner as in the above example, and the patterned layer was dyed under various conditions using the acidic cyan dye. The relationship was investigated using the value corresponding to the absorbance of FIG. 2 shows an example of the measurement. In the figure (11 (21 is casein membrane) thickness 1μ
In the case of m, (1) is a case where the dyeing temperature is 40°C, and (2) is a case where the dyeing temperature is 80°C. In addition, (3) is the case of plasma-treated casein with a thickness of 16 μm formed according to the method of the present invention (staining temperature is 50°C), and (4) is the casein of 0.6 μm casein that was dyed at 80°C without plasma treatment. Case 5 and 5 respectively indicate predetermined absorption intensity ranges.

As is clear from FIG. 1, pattern resolution is significantly improved according to the invention compared to the conventional method. The casein film thickness before pattern formation is the same as in the figure (11 (2)), so the improvement in resolution due to illegal processing is mainly due to the removal of the 1↓ area at the edge of the pattern by plasma treatment. This is thought to be due to the fact that the dimensions have become narrower.

The thickness of the casein film treated according to the present invention is 0.4 from the initial thickness.
However, as shown in Fig. 2, a membrane thickness of at least 1 μm or more is required to obtain a predetermined spectral charge (absorption intensity), and (0.6 μm) 1. For I-, the desired value cannot be achieved even if the staining conditions (temperature If) are changed.

), even with a thickness of 06 μm, the armor time and M
Desired spectral characteristics were obtained even under single-phase staining conditions. 1st
In the figure, the minimum film thickness for obtaining desired spectral characteristics and the pattern resolution at that time are shown in full.

In other words, conventionally, a minimum film thickness of 1 μm or more was required to satisfy the spectral characteristics, and the resolution was about 10 μm, but with the single method, the spectral resolution is 0.6 μm even if the film thickness is reduced by N-k. Although there are no problems in terms of characteristics, it can be seen that the resolution is significantly improved to ~4 μm.

It is clear that the plasma treatment of the present invention greatly improves the stainability, and this is due to the compositional and porous alteration of the casein surface caused by the plasma treatment. This is thought to be due to the increased affinity for the above dye.

Similar effects are observed not only in the above-mentioned oxygen plasma but also in plasma gases containing air and nitrogen 'r-, and it is also possible to use these three gases in the present invention.

As described in detail above, the present invention improves the process of the dyeing method, thereby making it possible to form a high aperture color filter, which was difficult to achieve with the conventional method, and which is also extremely advantageous in terms of mass production. be.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the 1yj relationship between casein film thickness and pattern resolution, and FIG. 21 is a diagram showing the relationship between 1 spectral characteristics and staining time.

Claims (2)

[Claims] (1) In the method of fully forming a color fin layer on a solid-state image pickup device, the photosensitive dye-receiving layer provided on the device is fully exposed and developed to form a desired number of turns, and then the step of completely dyeing the Bakun coated layer is performed. A method for manufacturing a color filter, which includes a step of first treating the surface with plasma gas. (2) Claim m1 characterized in that the plasma gas contains at least one of oxygen, air, and nitrate f;c
2. Method for manufacturing a color filter as described in Section 1.