JPS63113456A - Method for stripping resist film - Google Patents

Abstract

PURPOSE:To permit thorough stripping of a resist film contg. Si from a high- polymer film by treating the resist film with hydrofluoric acid or acidic soln. essentially consisting thereof before treating the resist film with a stripping liquid consisting of an ordinary org. solvent. CONSTITUTION:The resist film contg. silicon (Si) is first treated with hydrofluoric acid or the acidic soln. essentially consisting thereof and is then treated with the stripping liquid consisting of the org. solvent at the time of finely working the resist film by dry etching, then stripping said film. The hydrofluoric acid, soln. mixture composed of hydrofluoric acid and ammonium fluoride, soln. mixture composed of hydrofluoric acid, ammonium fluoride and acetic acid, etc., are used as the acidic soln. The thorough stripping away of the resist film contg. Si from the high-polymer film and the formation of the precise pattern are thereby permitted.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for removing a resist film, and in particular, after dry etching a polyimide polymer film or an organic polymer film as a lower layer material of a multilayer resist, The present invention relates to a method for easily peeling off a resist film formed thereon.

(Conventional technology) Conventionally, etching of polyimide polymer coatings has been carried out using a photoresist film or the like as a mask, and microfabrication of polyimide polymer coatings has been performed using a wet etching method using an alkaline aqueous solution as the etching liquid. , 10μm
After the through-holes are formed, the photoresist film that is no longer needed is treated with a stripping solution and removed.

Examples of the stripping solution for this photoresist film include organic solvents such as methyl ethyl ketone, trichlene, acetone, and methanol, J-100 (manufactured by Nagashio Sangyo Co., Ltd.), and S-50.
2 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) etc. are commonly used.

However, with the miniaturization of semiconductor devices, the interconnects have become smaller than 1 μm.
With the conventional wet etching method, there is a limit to the pattern processing accuracy, and gradually oxygen, CF4
Dry etching methods using reactive gases such as etching are becoming mainstream.

In addition, the lower layer material of the multilayer resist method is coated for the purpose of flattening the surface of the semiconductor element, and is particularly applied to semiconductor elements with a thickness of 1 μm or less in the wiring, and this lower layer material is etched by a dry etching method using oxygen. The pattern is being formed.

(Problems to be Solved by the Invention) The photoresist film used in this dry etching method has a higher resistance to dry etching with oxygen than polyimide polymer films or other organic polymer films, that is, it has a high selectivity. Because a high value is desired,
Polymer compounds containing silicon oxide and the like are commonly used.

However, these resist films containing silicon (Si) have a problem in that they are not completely removed from the polymer film using only the stripping solution using the organic solvent or phenol solution and remain on the film.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a resist film stripping method that completely strips a resist film containing St from a polymer coating.

(Means for Solving the Problems) The present invention provides that when a resist film containing silicon (Si) is microfabricated by dry etching and then peeled off, the resist film is first treated with hydrofluoric acid or the like. The present invention relates to a method for stripping a resist film, which is treated with an acidic solution as a component and then treated with an organic solvent stripping solution.

A resist containing silicon is formed on a polyimide polymer coating or on an organic polymer coating having one or more resist layers.

The polyimide polymer coating is prepared by combining a carboxylic acid anhydride and a diamine in a solvent such as dimethylacetamide, dimethylformamide, dimethylsulfoxide, N-methyl-2- and lolidone under anhydrous conditions, preferably at a temperature of 50°C or lower. A stirring reaction is carried out to obtain a polyamic acid, which is then heat-treated at a temperature ranging from 100°C to 400°C,
Obtained by dehydration and ring closure. If necessary, diaminomonoamide, diamine having a siloxane bond, etc. are used. For example, there is PIQSPIX (manufactured by Hitachi Chemical Co., Ltd.).

Organic polymer coatings include acrylic polymers such as polymethyl methacrylate, polyglycidyl methacrylate, and polyethyl acrylate, phenolic resins such as polyvinylphenol, phenol novolac, and cresol novolac, cyclized polyisoprene rubber, and cyclized polyester. Rubber polymers such as butadiene rubber are used.

Resists containing silicon (Si) used in the present invention include silicone-based negative and positive resists, such as those published in the magazine "Semiconductor World"
iconductor World) R59198
6,1'', trimethylsilylstyrene-chloromethylstyrene copolymer, trimethylsilylnitrile-added novolak, ladder-type silicone resin-containing 0FPR, etc. can be used.

In addition, phenol resin and cis-(1,3,5゜7-titrahydroxy)-1,3,5,7-tetraphenylcyclotetrasiloxane and the general formula (where R1 is a phenyl group and a carbon number of 1 to 4) represents a group selected from the group consisting of alkyl groups, and the ratio of phenyl group/alkyl group is 1
As above, R2 is an element or group selected from the group consisting of hydrogen, a phenyl group, and an alkyl group having 1 to 4 carbon atoms, and hydrogen accounts for 1/2 or more of the total R2). A resist containing a mixture of polysilsesquioxane and polysilsesquioxane is preferable because it can be developed with an alkaline aqueous solution.
Furthermore, materials obtained by adding a quinonediazide compound or an azide compound to these materials can be used as a photoresist, and therefore have high utility value.

In the dry etching in the present invention, after forming the polyimide polymer film or organic polymer film, the resist containing St used in the present invention is spin-coated with a spinner to form an upper layer. The resist film is irradiated with radiation such as ultraviolet rays and electron beams, developed and rinsed to obtain the desired resist pattern.
After that, dry etching is applied.

As for the dry etching conditions, oxygen is mainly used as the gas, but a small amount of other gas may also be mixed. The pressure is in the range of 0.1 to 1QmTorr, the time is within one hour, the output is 1000W or less, and the bias voltage is usually set to 1000V or less.

In the present invention, to remove the resist film having St after dry etching, the resist film is first treated with hydrofluoric acid or an acidic solution containing hydrofluoric acid as a main component, and then treated with an ordinary organic solvent-based stripping solution. It will be done.

As this acidic solution, a mixed solution of hydrofluoric acid, hydrofluoric acid and ammonium fluoride, a mixed solution of hydrofluoric acid, ammonium fluoride and acetic acid, etc. are used.

The hydrofluoric acid solution is preferably a 46% by weight aqueous hydrofluoric acid solution diluted 5 to 100 times.

A mixed solution of hydrofluoric acid and ammonium fluoride is
The mixing ratio of the 46% by weight aqueous hydrofluoric acid solution and the 40% by weight ammonium fluoride aqueous solution is preferably within the range of 1:1 to 1:50 in terms of weight ratio of the hydrofluoric acid aqueous solution:ammonium fluoride aqueous solution. In addition, the mixed solution of hydrofluoric acid, ammonium fluoride, and acetic acid includes 1 to 20% by weight of a 46% by weight aqueous hydrofluoric acid solution, 70 to 80% by weight of a 40% by weight aqueous ammonium fluoride solution, and 10 to 10% by weight of acetic acid.
A mixing ratio of 30% by weight is preferred.

In the treatment with an acidic solution, it is preferable to immerse the material in this solution at a temperature of 10 to 40° C. for less than 10 minutes.

As the organic solvent-based stripping solution, methyl ethyl ketone, trichlene, acetone, methanol, N-methyl-2-pyrrolidone, hydrazine, etc. are used, and phenol, O-
Commercially available J-100 and S-502 (trade names), which are mixtures of dichlorobenzene and tetrachloroethylene, can also be used.

The immersion in the organic solvent-based stripping solution is preferably carried out at a temperature from room temperature to around the boiling point of the solvent for 30 minutes or less.

In addition to the above-mentioned immersion method, a method of spraying, a method of immersing in a stripping solution and applying ultrasonic waves, etc. can also be used for the treatment with the stripping solution.

(Function) In the present invention, before treating the resist film with an ordinary organic solvent-based stripper, it is treated with hydrofluoric acid or an acidic solution containing hydrofluoric acid as a main component. It is thought that dry etching produces silicone-based oxides that are poorly soluble in organic solvent-based stripping solutions (magazine [Solid State Technology (SOLID)]).
d 5tate technology) J Japanese version,
R521985, 10) is carried out for the purpose of removing this silicone-based oxide.

(Example) Hereinafter, the present invention will be explained with reference to Examples and Comparative Examples. In addition, parts in the following examples mean parts by weight.

Example 1 On a silicon wafer covered with a silicon oxide film (S i 02 ) with a thickness of 0.5 μm, polyamic acid (PIQ: manufactured by El Rikkasei Kogyo Co., Ltd.), which is a precursor of a polyimide polymer, was applied at 300 rpm for 30 min. Apply with a spinner for 60 minutes at 100°C in a N2 gas atmosphere, and then apply at 200°C for 30 minutes.
Further heat treatment was performed at 350° C. for 60 minutes to form a 2 μm thick polyimide polymer film.

Next, cis-(1,3,5,7 -Titrahydroxy”)-1
, 6 parts of 3,5,7-tetraphenylcyclotetrasiloxane (abbreviated as phenyl-T4(OH)4) and polyphenylsilsesquioxane (GR-95 manufactured by Owens 111inois).
After adding and mixing 9 parts of
A photoresist film having a thickness of 1 μm was formed by prebaking at ℃ for 30 minutes.

Furthermore, using Hitachi reduction projection exposure apparatus RA-501, 1
．． After exposure for 1 second, development was carried out by immersion in an organic alkaline aqueous solution (tetramethylammonium hydroxide 2.38% by weight aqueous solution) as a developer at 23° C. for 30 seconds.
After rinsing with running water, a medium 1 μm pattern was obtained by post-baking at 100° C. for 30 minutes.

After that, dry etching equipment manufactured by ULVAC (product name C) was used.
3E-1110) using oxygen (etching tank pressure: 10 mTorr, oxygen flow rate: 205 CCM, bias voltage = 350 V, supply type crab toow, power application time: 13 minutes). A medium 1 μm pattern was formed on the polymer film.

After this dry etching is completed, the photoresist film formed on the polyimide polymer film is mixed with a 46% by weight hydrofluoric acid aqueous solution, 40% by weight ammonium fluoride and acetic acid (weight% ratio 13/75/12). 23℃ in solution
When the photoresist film was immersed in water for 2 minutes, rinsed with water, dried, and then immersed in a phenolic stripping solution S-502 at 90° C. for 10 minutes, the photoresist film could be completely peeled off.

Example 2 On the same silicon wafer as used in Example 1, RG-3900B (manufactured by Hitachi Chemical Co., Ltd.) containing phenolic resin as the main component was spin-coated using a spinner as the lower layer material of the multilayer resist, and then A resist film having a thickness of 2 .mu.m was formed by hard baking at .degree. C. for 20 minutes.

The same photoresist as in Example 1 was applied onto this film in the same manner as in Example 1 to form an upper layer photoresist film. After that, Example 1
Exposure and development were carried out in the same manner as above to obtain a pattern with a width of 1 μm. This was dry etched under the same conditions as Example 1,
46@vol.% hydrofluoric acid aqueous solution diluted 20 times with water for 2 minutes at 23°C, rinsed with water, dried, and then diluted with N
-Methyl-2-pyrrolidone solution at 150℃ for 10 minutes?
When M was applied, the photoresist film could be completely peeled off and removed.

Example 3 A sample wafer that had been subjected to dry etching in Example 1 was added to a mixed solution of 46 wt% hydrofluoric acid aqueous solution and 50 wt% ammonium fluoride aqueous solution at a ratio of 1:6 (Di amount ratio) at 23°C. After 3 minutes of immersion in water, rinsing with water, drying, and 10 minutes of immersion in a methyl ethyl ketone solution at 70°C, the photoresist film could be completely peeled off.

Example 4 Positive electron beam resist RE- containing novolac resin and poly(2-methylpentene-1-sulfone) as main components
Phenyl-74 (OH) 4 to 100 parts of 5000P (solid content concentration 13.5% by weight, manufactured by Hitachi Chemical Co., Ltd.)
4 parts and polyphenylsilsesquioxane (GR-950
) was added, adjusted, filtered through a 0.2 μm filter, and applied onto the polyimide polymer film used in Example 1 to form a resist film with a thickness of 1 μm.

Next, on this sample wafer, using an electron beam lithography device,
After performing electron beam drawing of a test pattern at an acceleration voltage of 30 kV and an electron beam irradiation amount of 4.0 x 10''6 coulombs/-, the upper layer resist was drawn using a 2.38% by weight aqueous solution of tetramethylammonium hydroxide as a developer. The film was developed to obtain a pattern.

Dry etching was performed in the same manner as in Example 1, immersed in a mixed solution of hydrofluoric acid, rinsed with water, dried, and then soaked in phenolic stripper S-502 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) at 90°C for 10 minutes. When the photoresist film was applied at a rate of 1/M for 1 minute, the photoresist film could be completely peeled off.

Example 5 Phenyl-T4 was added to 100 parts of RD-200ON (a negative telephoto ultraviolet resist whose main components are a phenolic resin and an azide compound) (solid content concentration 24% by weight, manufactured by Hitachi Chemical Co., Ltd.).
After adding and mixing 410 parts of (OH) and 2 parts of polyphenylsilsesquioxane (GR-950), 0.2 parts of
On the polyimide polymer film used in Example 1 which had been filtered through a μm filter, a resist film having a thickness of 1 μm was formed by prebaking at 90° C. for 20 minutes.

Using an exposure device manufactured by Mikasa (product name MA-10), 10
After exposure for seconds, it was immersed in a 1 M% tetramethylammonium hydroxide aqueous solution at 23° C. for 80 seconds, rinsed with water, and then post-baked at 100° C. for 30 minutes to obtain a 1 μm pattern.

After that, dry etching was applied in the same manner as in Example 1,
It was immersed in a mixed solution of hydrofluoric acid, rinsed with water, dried, and then soaked in phenolic stripper S-502 at 90°C.
When immersed for 0 minutes, the above resist film could be completely peeled off and removed.

Comparative Example In Example 1, the photoresist film after dry etching was not immersed in a mixed solution of hydrofluoric acid, ammonium fluoride, and acetic acid, but was immersed only in S-502 at 90°C for 10 minutes. The photoresist film could not be completely peeled off.

(Effects of the Invention) According to the resist film peeling method of the present invention, the resist film containing St can be completely peeled off from the polymer coating and a precise pattern can be formed.

Claims (1)

[Claims] 1. After finely processing a resist film containing silicon (Si) by dry etching, when peeling it off, the resist film is first treated with hydrofluoric acid or an acidic solution containing silicon as a main component. A method for stripping a resist film, the method comprising: treating the resist film with an organic solvent-based stripping solution. 2. A resist film containing silicon (Si) is coated with a phenol resin and cis-(1,3,5,7-tetrahydroxy)-1
, 3,5,7-tetraphenylcyclotetrasiloxane and the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, R_1 represents a group selected from the group consisting of phenyl group and alkyl group having 1 to 4 carbon atoms. , and the ratio of phenyl group/alkyl group is 1 or more, R_2 is an element or group selected from the group consisting of hydrogen, phenyl group, and alkyl group having 1 to 4 carbon atoms, and hydrogen accounts for 1 or more of the total R_2. 2. The method for removing a resist film according to claim 1, which comprises a mixture with polysilsesquioxane represented by 1/2 or more of