JPS5935467A - Manufacture of solid-state image pick up element - Google Patents

Abstract

PURPOSE:To obtain the titled element to generate no change in the light characteristic by a method wherein the colored pattern of a concise construction is formed directly on a wafer using a resist enabled to use a solvent to scarcely damage the wafer and coloring matter, while using coloring matter not to be corroded by the resist solvent thereof. CONSTITUTION:The poly-1,1-dimethyltetrafluoropropyl methacrylate solution is applied at the prescribed thickness according to the spinner application method on the wafer formed with the solid-state image pick up elements of the plural number. The methacrylate polymer thereof containing fluorine is the matter to be expressed by the formula, (at this time, R1 and R2 represent hydrogen or an alkyl group, and R3 represents an alkyl group combined with at least one fluorine to respective carbons), and the positive resist mask is formed using the polymer thereof. Then coloring matter consisting of lead-phthalocyanine is evaporated thereon, and is immersed in a solvent to dissolve only the resist mask without dissolving coloring matter, and moreover without damaging the spectral properties to remove the mask.

Description

[Detailed Description of the Invention] The present invention is a C0D (charge coupled device), a B
The present invention relates to a method of manufacturing color solid-state image sensors such as BD (packet pre-gate device) and C (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 wafer on which a solid-state image sensor is formed. A method of forming a thin film of a dye such as a pigment by vapor deposition is known (
JP-A-55-146406).

According to this method, a colored layer can be formed from the dye itself, so compared to the conventional dyeing method in which a mordant layer such as gelatin or poval is dyed with an organic dye, it is not only thinner and more durable. It has excellent microfabrication properties on uneven surfaces such as wafers on which solid-state imaging devices are formed, and can be processed using a non-aqueous process, making it an excellent and accurate method for forming directly on wafers. -I get it.

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

This method involves forming a pattern on a dye layer with a resist, and then using this as a resist mask, the non-resist portions of the dye layer are removed by evaporation in an ion or plasma atmosphere 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 must be made quite thick because it is also removed at the same time during dry etching. ,・Therefore, there is a drawback that pattern accuracy is deteriorated.

Furthermore, in order to prevent damage to the wafer itself or the color elements of the already patterned color filter 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 whenever filter transmittance decreases and flare light increases. 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, resulting in a problem that the heat resistance of the color filter as a whole also deteriorates.

On the other hand, a resist mask is provided below the dye layer to be removed, and the dye layer above it is removed by removing the lower resist mask from the substrate without directly acting on the dye layer. A so-called reverse etching method (or lift-off method) in which the material is removed physically at the same time is known (Japanese Patent Publication No. 47-16815).

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 with only the colored layer remaining on the mask. However, the reverse etching method has not been widely used until now.

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

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 such a resist is used, coating, development, and removal of the resist, St substrate of the wafer, and A
The metal electrode formed on the wafer may be adversely affected by oxidation, corrosion, etc., and the color element dyes and pigments formed on the wafer may be dissolved or may not reach the level of dissolution.
It often significantly impairs spectral properties. Further, as shown in FIG. 5, for example, a portion 11 where the stable adhesion area between the color element 10 and the wafer is reduced due to unevenness on the surface of the wafer 1.
Because it hits the slope of unevenness on 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 enter under the color element where the adhesion area is small or to the thin part of the film. Due to staining, etc., color elements may peel off.

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

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, using 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 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.

In the method for manufacturing a color solid-state image sensor according to the present invention, a resist mask is applied to Ueno 1 on which a solid-state image sensor is formed using a positive resist mainly composed of fluorine-containing methacrylate polymer units represented by the following structural formula. A step of forming a dye 1- by vapor depositing a dye selected from metal-free phthalocyanine and gold λ1r4 phthalocyanine on the wafer on which the resist mask is formed, and removing the resist mask from the wafer. This method is characterized by a step of selectively removing the dye layer on the resist mask at the same time.

R8 is at least 1 for each carbon. That is, the present invention is characterized in that a fluorine-containing polymethacrylate having the structure shown by the above formula is used as the main component of a positive resist, and a phthalocyanine dye is used. .

The resist developing solvent in reverse etching is originally limited to a limited number of types that do not dissolve the dye used but dissolve the resist, and the dyes that can be used are rarely severely restricted due to the relationship with the imaging solvent. do not have. However, the positive resist used in the present invention includes esters,
It dissolves well in good solvents with high solubility such as aromatics and halogenated hydrocarbons, as well as poor solvents with low solubility such as alcohols, so various solvents can be used as developing solvents. .

Therefore, it is difficult to damage the wafer or the dye, and the range of dyes that can be used is greatly expanded, making it very effective for forming a desired colored pattern. Therefore, the reverse etching method is used to manufacture color solid-state image sensors with a simple structure. This is what makes it possible.

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. Suitable examples of typical resists include the following.

Examples of the dissolving solvent for dissolving the positive resist used in the present invention include alcohols such as methanol, ethanol, propatool, isopronochloro, and butanol;
Ketones such as aceto/, methyl ethyl ketone, methyl imbutyl ketone, methyl acetate, ethyl acetate, propyl acetate.

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 Ueno 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. Due to its affinity for resist films and ease of controlling solubility,
Alcohols such as methanol, ethanol, propatool, isopropanol, butanol are particularly suitable.

It is also possible to mix ketones and esters with alcohols. As the mixed solvent, a combination of isopropanol and a small amount of 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 the dye for reverse etching, it is preferable to use a dye that can be vapor deposited in nature, is insoluble in the resist processing bath, and does not impair the spectral characteristics. In this regard, the phthalocyanine dye used in the present invention not only does not dissolve in the developing solvent used for fluorine-containing polymethacrylate resists, but also does not cause any change in spectral characteristics even in solvents with weak solubility such as alcohols. It is something.

Therefore, in combination with a positive resist in the present invention, it is very effective for forming colored patterns having desired spectral characteristics, especially blue and green.

Phthalocyanine has a skeleton shown in the structural formula below. Metal phthalocyanine has various metal ions coordinated to the four central nitrogen atoms, and metal 7-7 thalocyanine has two aqueous atoms bonded to a metal base. be.

N Examples of typical phthalocyanines are metal-free phthalocyanine and copper phthalocyanine.

Beryllium phthalocyanine/, magnesium phthalocyanine, zinc phthalocyanine, titanium phthalocyanine,
Tin phthalocyanine, lead phthalocyanine, vanadium phthalocyanine, chromium phthalocyanine, molybdenum phthalocyanine.

Manganese phthalocyanine, iron phthalocyanine.

Examples include cobalt phthalocyanine, nickel phthalocyanine, palladium phthalocyanine, and platinum phthalocyanine.

According to the method of the present invention, since the patterning process and the etching process of the dye layer are imitative, there is no risk of further erosion of the wafer or the already formed color elements, and therefore no intermediate protective film is required. .

Therefore, since the colored layer is only a dye layer, there is no absorption or reflection of light by the medium 1141 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. Furthermore, 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 variation in spectral characteristics. It has remarkable effects such as .

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.

The present invention will be explained in detail below 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 using a spinner or the like on the unihull l 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 developing. 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 phthalocyanine dye layer 4 having necessary 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 about 1,000 to 10,000 λ.

Next, in order to remove the resist mask under the dye layer, the resist mask is immersed in a solvent that dissolves or peels only the resist mask from the substrate without dissolving the dye and 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 resist mask position 14 according to the pattern.

By repeating these steps as many times as there are different colors, a product having a gradual color pattern having a plurality of colors can be manufactured.

Example I Poly 1,1-dimethyltetrafluoroptetrapyrumethacrylate (R+ = R2 = CHs, R
An 8-fold f% MIBK (methyl isobutyl alcohol) solution of s=CFtCFtH) was applied to a film thickness of 7000 people. After drying, prebaking at 150 to 200°C for 30 to 60 minutes, mask exposure in a mosaic shape with far ultraviolet light, and immersion in a 70% IPA (isopropyl alcohol) and 30% MI BK solution for 3 minutes. A resist mask was formed.

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 lead phthalocyanine (manufactured by Tokyo Kasei), which had been placed in a molybdenum sublimation boat in advance, was heated at a vacuum level of 10-6 to 10' torr and placed on top of the urethane. Steaming in the thickness of a person
I did 2W. The wafer after vapor deposition was taken out from the vacuum apparatus and immersed in a 10% solution of IPA90q6MII3 for 2 minutes to dissolve and remove the resist mask. At this time, the dye layer was not attacked at all. Through these steps, a mosaic-like green monochrome filter was formed.

Note that this same process is performed using a commercially available positive resist (product name:
0DUR1013, manufactured by Tokyo Ohka Kogyo), when the resist was removed with a special developer (xylene 90%), some of the vapor-deposited dye was dissolved, and the spectral transmittance was 8 to 15% in the entire band. As a result, it has been difficult to form a filter with desired properties.

In addition, a positive resist (product name: 0DUR-1
000, Tokyo Ohka M), but with special development W < main component: isoamyl acetate), the peak wavelength of the spectral transmittance shifted by about 5 degrees, and the transmittance also decreased by about 5 degrees, making it difficult to achieve the desired characteristics. Filter formation was difficult.

Furthermore, positive resist (AZ1350 Shipley M)
However, when the undermask was removed with a special developer (alkaline aqueous solution), the Al electrode on the wafer was eroded, and some of the deposited dye was dissolved, resulting in unsatisfactory color solid-state imaging. It was difficult to form the element.

Example 2 Polyhexafluorobutyl methacrylate (R.

= R2= H, Rs = CFt CFHCFs
) A green mosaic filter could be formed in the same process as in Example 1 using an 8% by weight MIBK solution.

At this time, the dye layer was not attacked and no change in spectral characteristics occurred. Note that IPA was used as a developing and resist mask removal solvent.

Examples 3 to 7 Examples 1 and 2 were prepared using the following phthalocyanine compounds.
I created a filter in a similar way. Compared to the case of using a conventional positive resist, the wafer and spectral characteristics were not impaired.

Evaluation Criteria O Spectral transmittance hardly changes before and after dissolving and removing the resist mask Δ Spectral transmittance of 2 to 2 before and after dissolving and removing the resist mask
The spectral transmittance changes by about 3% before and after dissolving and removing the resist mask.
Things that change more than

[Brief explanation of drawings]

1, 2, 3, and 4 show the manufacturing process of a color solid-state image sensor according to the present invention. FIG. 1 shows the resist film manufacturing process, FIG. 2 shows the resist mask manufacturing process, and FIG. The dye N manufacturing process and FIG. 4 are explanatory diagrams of the color element manufacturing process. FIG. 5 is an explanatory diagram showing one form of color elements formed on a wafer. 1... Wafer 2 on which a solid-state image sensor is formed...
・Resist film 3...Resist mask 4...Color material layer 5...Color element

Claims (1)

[Claims] A step of forming a resist mask on a wafer on which a solid-state imaging device is formed using a positive resist mainly composed of fluorine-containing methacrylate polymerized units represented by the following structural formula, the resist mask A step of forming a dye layer by vapor depositing a dye selected from metal 7 leaf thalocyanine and metal phthalocyanine on the wafer on which the resist mask has been formed, and also selectively removing the dye layer on the resist mask at the same time by removing the resist mask from the wafer. 1. A method for manufacturing a color solid-state image sensor, comprising the step of removing the solid-state image sensor. Record R2CR1″