JPS59127861A - Manufacture of color solid-state image pickup element - Google Patents

Abstract

PURPOSE:To remove the absorption and reflection of light and the reduction of transmitted light due to an intermediate protective film and a resist mask, and to improve spectral characteristics by using a resist to which a solvent, which hardly damages a wafer and a pigment, can be employed while using the pigment, which is not damaged by these resist and solvent. CONSTITUTION:A compound mainly comprising a polymethacrylate polymerization unit containing fluorine shown in the formula I (R1 and R2 are hydrogen or alkyl groups and R3 is an alkyl group in which at least one fluorine is combined with each carbon) is used as the positive type resist. The pigment consisting of a perilene tetracarboxylic acid derivative shown in the formula II (R4 is hydrogen, an alkyl group or allyl group) is used. The positive type resist is dissolved in the predetermined solvent and changed into a solution of proper viscosity as processes. The resist mask 3 is formed by applying the solution as a resist film 2 on the wafer 1 by using a spinner, etc. in the desired wafer and developing the film 2. The pigment layer 4 consisting of the perilene tetracarboxylic acid derivative having necessary spectral characteristics is formed on the resist mask 3 through evaporation.

Description

[Detailed description of the invention] The present invention)-jccD (charge coupled device)
, B131) (packet pre-gate device), C
The present invention relates to a method of manufacturing a color solid-state image sensor such as an ID (charge injection device).

As a method for producing a solid-state image sensor equipped with a color filter for color separation, that is, a color solid-state image sensor, there is a method of directly forming a color filter on a substrate on which a solid-state image sensor is formed. A method is known in which a thin film of a pigment such as a dye or pigment is formed by vapor deposition (Japanese Unexamined Patent Publication No. 146406/1983).

According to this method, a colored layer can be formed using the dye itself, so compared to the conventional dyeing method in which a mordant layer such as gelatin or popal is dyed with an organic dye, it is not only possible to make the device thinner, but also to form a solid-state image sensor. It has excellent microfabriability on uneven surfaces such as wafers on which wafers are formed, and can be processed in a non-aqueous process, making it an excellent method with good precision and suitable for direct formation on wafers.

Dry etching has been widely used as a method for patterning the dye layer formed by vapor deposition.

In this method, a pattern is formed on a dye layer using a resist, and then the non-resist portions of the dye layer are removed by evaporation in an ion or plasma atmosphere using the cracks as a resist mask to form a pattern.

However, with this method, it is difficult to select a resist with good etching resistance that can be formed on the dye layer, and the resist mask is also removed at the same time during dry etching, so the resist mask must be made quite thick. However, there are drawbacks such as deterioration of pattern accuracy.

Furthermore, in order to prevent the wafer itself and the color elements of the already patterned color filter from being damaged by dry etching, a transparent intermediate protective film is required for each color element formation of one color, and because this protective film and resist mask exist,
There are also drawbacks such as reduced filter transmittance and increased flare light. Furthermore, although the dye film itself has excellent heat resistance because it is vapor-deposited, the intermediate protective film and resist mask have poor heat resistance, so there is a problem that the heat resistance of the color filter as a whole also deteriorates.

On the other hand, by providing a large resist mask below the dye layer to be removed and removing the lower resist mask from the substrate without having any direct effect on the dye layer, the dye layer above it can be removed. A so-called reverse etching method (or lift-off method) is known (Japanese Patent Publication No. 47-16815), which physically removes the etchant at the same time.

This is a process in which a desired pattern is formed by forming a resist mask using a substance that can later be dissolved, mainly a positive type resist, then depositing a vapor-deposited dye layer on top of the resist mask, and then dissolving the resist mask. It is. According to the reverse etching method, a pattern is formed by removing the resist mask itself, so it has the advantage of having a simple structure of only the colored layer and no mask remaining.

However, the reverse etching method has not been widely used until now.

The reason for this is that it is difficult to form a resist mask without damaging the wafer or dye layer and to select a positive resist that is easy to remove.

That is, since the resin component of conventionally known positive resists is strong in order to be used as a mask, organic solvents, organic alkalis, and alkaline aqueous solutions with strong dissolving power are often used.

Therefore, when using such a resist, the Si substrate of the wafer, the M
It may cause adverse effects such as oxidation or corrosion on the metal electrodes formed on the wafer, or it may dissolve the dyes and pigments of the color elements formed on the wafer, or even if it does not dissolve, it may affect the spectral characteristics. It often causes significant damage. Furthermore, as shown in FIG. 5, for example, a portion 1 where the stable adhesion area between the color element IO and the wafer is small due to the unevenness of the surface of the wafer 1.
1 and the uneven slopes of the wafer surface, the part 12 where the color element film is thin and tends to break off becomes wider, which may cause the solvent to penetrate under the color element, which has a small adhesion area, or to the part where the film thickness is thin. Color elements may peel off due to penetration of solvent.

Thus, the lack of compatibility of conventional resists with the wafer and dye makes reverse etching on the wafer difficult.

Therefore, the present invention solves these drawbacks by using a resist that can use a solvent that does not damage the wafer or the dye, and on the other hand, uses a dye that is not attacked by these resist solvents. The present invention provides a method for manufacturing a color solid-state image sensor by directly forming a colored pattern with a simple structure on a wafer.

Another object of the present invention is to provide a method for manufacturing a high-performance color solid-state image sensor by using a dye whose optical properties do not change depending on the developing solvent of the resist.

The method for manufacturing a color solid-state image sensor according to the present invention includes applying the following structural formula [I
] A step of forming a resist mask using a positive resist mainly composed of fluorine-containing methacrylate polymerized units represented by the above, and perylenetetracarboxylic acid represented by the following structural formula [■] on the wafer on which the resist mask is formed. This method is characterized by the steps of forming a dye layer by vapor-depositing a derivative dye, and simultaneously selectively removing the dye layer on the resist mask by removing the resist mask from the wafer.

It.

CI'll or here represents hydrogen or an alkyl group, R3 represents an alkyl group with at least one fluorine bonded to each carbon, and ``Hiki'' represents hydrogen, an alkyl group, or an alcohol. That is, the main feature of the present invention is that a fluorine-containing polymethacrylate having a structure represented by formula 13 is used as a main component of a positive resist, and a dye of a perylenetetracarboxylic acid derivative is used.

The developing solvent for the resist in IJ hearth etching is originally limited to a limited number of types that do not dissolve the dye used and can dissolve the resist, and as a result, the dyes that can be used in relation to the developing solvent are severely limited.・There are many cases where However, the positive resist used in the present invention is
Various solvents are used as developing solvents because they dissolve well in good solvents with high solubility such as esters, aromatics, and halogenated hydrocarbons, as well as in poor solvents with low solubility such as alcohols. It is possible. Therefore, it does not damage the wafer or dye, the range of dyes that can be used is greatly expanded, and it is very effective in forming a desired colored pattern. It enables manufacturing.

This fluorine-containing polymethacrylate resist has excellent solubility, but this is due to the effect of steric hindrance due to the ester group in the side chain, the increase in energy absorption efficiency due to the introduction of fluorine, and the localization of electrons due to the increase in electronegativity. This is thought to be due to the effect of promoting main chain cleavage. The following are suitable examples of typical resists. Examples of dissolving solvents for dissolving the positive resist used in the present invention include methanol, ethanol, propatool, isopropatool, and butanol. alcohol, acetone,
Ketones such as methyl ethyl ketone and methyl isobutyl ketone, methyl acetate, ethyl acetate, and tetrapyrlacetate.

Esters such as butyl acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, etc. can be used. It may also be a mixture of these.

In order to apply a resist onto a wafer on which a dye layer has already been formed, it is preferable to use alcohol as the main agent, although it depends on the type of dye. As the developing solvent, basically the above-mentioned dissolving solvents can be used, but in order to selectively dissolve only the exposed portion whose molecular weight has decreased due to exposure, it is preferable to select a solvent having a lower dissolving power than the dissolving solvent. Alcohols such as methanol, ethanol, propatool, inpropatol, and butanol are particularly suitable because of their affinity for resist films and ease of controlling solubility. It is also possible to mix ketones and esters with alcohols. As the mixed solvent, a combination of isopropanol and Shoka's methyl isobutyl ketone is suitable.

To remove the resist mask from the substrate, the developing solvent can basically be used as is by irradiating the resist mask with light or the like in advance.

Since the main chain scission of this fluorine-containing polymethacrylate occurs by obtaining energy in the far ultraviolet region, far ultraviolet light, an electron beam, or the like is suitable as a light source for patterning.

On the other hand, as a dye for reverse etching, it is preferable to use a dye that can be vapor deposited in nature and is insoluble in a resist processing solvent so that the spectral characteristics are not impaired by scratching. In this regard, the perylenetetracarboxylic acid derivative used in the present invention not only does not dissolve in the developing solvent used for fluorine-containing polymethacrylate resists, but also changes in spectral characteristics even in solvents with weak solubility such as alcohols. It does not occur at all.

Therefore, in combination with a positive resist in the present invention, it is very effective in forming colored patterns having desired spectral characteristics, particularly in the red range. Preferred examples of typical perylenetetracarboxylic acid derivatives include the following.

Water) ■ Those in which m- is -H in the above formula ■ Those in which m- is -CH in the above formula According to the method of the present invention, no etching treatment of the dye layer is required during patterning.
There is no risk of further erosion of the wafer or the color elements already formed, and therefore no intermediate protective coating is required. Therefore, since the colored layer is only a dye layer, there is no absorption or reflection of light by the intermediate protective film or resist mask, and no reduction in transmitted light occurs. Furthermore, since there is no need for an intermediate protective film or resist mask that has poor heat resistance, a color filter with excellent heat resistance can be obtained. “Also, since the dye is formed by vapor deposition, even if the surface of the wafer on which it is vapor-deposited is uneven, the dye layer will be formed parallel to the surface, so there will be no local variations in spectral characteristics. It has a remarkable effect that it does not occur.

Further, the method for manufacturing a color solid-state image sensor according to the present invention can be continued after the wafer has undergone steps such as oxidation, etching, deposition, and diffusion and has the function of an image sensor.

Thereby, manufacturing of wafers and manufacturing of color filters can be performed continuously.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

First, the positive resist used in the present invention is dissolved in a predetermined solvent to form a solution with an appropriate viscosity. If necessary, additives such as surfactants may be added.

A resist film 2 is applied onto a desired wafer 1 using a spinner or the like as shown in FIG. After drying, prebaking is performed under appropriate temperature conditions.

Next, a resist mask 3 as shown in FIG. 2 is formed by exposing to an electron beam or deep ultraviolet light in a predetermined pattern shape and then removing the resist. If necessary, pretreatment is performed for the purpose of alleviating strain on the resist film before development, and rinsing treatment is performed after development for the purpose of suppressing swelling of the resist film. Further, after forming the resist mask, the entire surface is irradiated with an electron beam or far ultraviolet light.

This makes it easier to dissolve and remove the resist mask later by cutting the main chain of the resist.
It is also possible to omit it. If it is omitted, it is necessary to use a solvent with stronger solubility.

Next, as shown in FIG. 3, a dye layer 4 of a perylenetetracarboxylic acid derivative having reliable spectral characteristics is formed on the resist mask 3 by vapor deposition. The thickness of the dye layer is determined depending on the desired spectral characteristics, but is usually 1000 to 10000.
It is about λ.

Next, in order to remove the resist mask under the dye layer, the resist mask is immersed in a solvent that does not dissolve the dye and only dissolves or peels the resist mask from the substrate without damaging the spectral characteristics.

Removal of the resist mask simultaneously removes the dye layer thereon, and to assist in this removal, it is also effective to apply ultrasonic energy during immersion.

In this way, the first color element 5 is formed as shown in FIG. If further different color elements are to be formed on the same wafer, the above steps may be repeated while shifting the position of the resist mask according to the pattern.

By repeating these steps as many times as there are different colors, it is possible to produce a product having a colored pattern with a plurality of colors.

Example 1 Poly 1,1-dimethyltetrafluoropropyl methacrylate (1'=Ry=CH,,R,3=C) was coated on a wafer on which 10 CODs were formed using a spinner coating method.
An 8 weight XMIBK (methyl isobutyl alcohol) solution of F', CF, H) was applied to a film thickness of 7000 people.

After drying, prebaking at 150 to 200°C for 30 to 60 minutes, a mosaic-shaped mask exposure was performed using deep ultraviolet light, and the process was completed using PA (isopropyl alcohol) 70.
%, MI BK 30% solution for 3 minutes to form a resist mask.

Next, the entire surface of the wafer on which the resist mask was formed was irradiated with deep ultraviolet light to make the resist mask soluble in a solvent.

This wafer was placed in a vacuum device and evacuated, and Irgazin Red BPT (trade name, manufactured by Ciba Geigy), the dye of the above-mentioned type 0, which had been placed in a molybdenum sublimation boat in advance at a vacuum level of 10'' to 10' torr, was applied. The wafer was heated and deposited to a thickness of IK3000λ.The wafer after deposition was taken out of the vacuum apparatus and placed in IPA90XMI.
The resist mask was dissolved and removed by immersion in a 10% BK solution for 2 minutes. At this time, the dye layer was not attacked at all. Through these steps, a mosaic red color filter was formed.

Note that this same process is performed using a commercially available positive resist (product name:
0DURtOl 3. When trying to remove the resist using a special developer (90% xylene), the evaporated dye was eroded and the spectral transmittance changed over the entire band, resulting in the desired characteristics being lost. It was difficult to form a filter.

In addition, a positive resist (product name: 0DUR-10
00, manufactured by Tokyo Ohka), but the special developer (main component;
(isoamyl acetate), the spectral transmittance changed by about 5%, making it difficult to form a filter with desired characteristics.

Furthermore, when we tried using a positive resist (AZ 1350 manufactured by Shipley), when the resist mask was removed with a special developer (alkaline aqueous solution), the M electrode of the wafer was eroded, and some of the vapor-deposited dye was also eroded. Therefore, it was difficult to form a satisfactory color solid-state image sensor.

Example 2 Polyhexafluorobutyl methacrylate (R1 = gift =
8 wt% MI of H, Hiki = CF, -C'F'H-CF3)
A red mosaic filter could be formed using the BK solution in the same process as in Example 1. At this time, the dye layer was not attacked and no change in spectral characteristics occurred. Note that IPA was used as a solvent for removing the resist mask and resist mask.

Examples 3 to 9 Filters were created in the same manner as in Examples 1 and 2 using the following perylenetetracarboxylic acid derivatives. In all cases, the spectral characteristics were not impaired compared to when a conventional positive resist was used.

Evaluation criteria: ○The spectral transmittance hardly changes before and after dissolving and removing the Ni-resist mask.△The spectral transmittance is 2 to 2 before and after dissolving and removing the Ni-resist mask.
Those whose spectral transmittance changes by about 3% × those whose spectral transmittance changes by 5 or more before and after dissolving and removing the Niresist mask

[Brief Description of the Drawings] Fig. 1, Fig. 2, Fig. 3, and Fig. 4 show the manufacturing process of a color solid-state image sensor according to the present invention, in which Fig. 1 shows the resist film manufacturing process, and Fig. 2 shows the resist film manufacturing process. FIG. 3 is an explanatory diagram of the mask manufacturing process, FIG. 3 is a dye layer manufacturing process, and FIG. 4 is a color element manufacturing process. FIG. 5 is an explanatory diagram showing one form of color elements formed on Unino. 1...Unino-2 where the solid-state image sensor is formed
...Resist film 3...Resist mask 4...Dye layer 5...Color element applicant Canon Corporation

Claims (1)

[Claims] A step of forming a resist mask on Ueno on which a solid-state image sensing device is formed using a positive resist having a fluorine-containing methacrylate polymerized unit represented by the following structural formula [ID] as a living body. , Ueno film on which the resist mask is formed.
- a step of vapor depositing a color patch of a perylenetetracarboxylic acid derivative represented by the following structural formula (II) on top to form a dye layer, and simultaneously removing the resist mask from the dye layer on the resist mask. 1. A method for manufacturing a color solid-state image sensor, comprising the step of selectively removing also. (ID or here, 龄 and 零 are hydrogen or an alkyl group, 8 is an alkyl group in which at least one fluorine is bonded to each carbon, R6 is hydrogen, an alkyl group, or an aryl group.