JPH0769618B2 - Stripping agent for photoresist - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photoresist used for manufacturing a semiconductor circuit pattern, and more particularly to a photoresist remover used for removing a positive photoresist after use.

Photoresist is a photosensitive resin used in the production of semiconductor circuit patterns, and is used for applying operations such as etching and impurity injection to desired positions on an inorganic substrate such as a silicon wafer. Photoresists are roughly classified into a positive type in which light is easily dissolved in a developing solution and a negative type in which they are easily dissolved in a developing solution, and they are properly used according to their characteristics. The positive resist is most commonly a mixture of an alkali-soluble novolak resin and a quinonediazide compound as a photosensitizer, and since high resolution is obtained,
The amount of resist used has rapidly increased in response to the recent demand for higher integration.

In the process of manufacturing a semiconductor circuit pattern, a resist is uniformly coated on an inorganic substrate, exposed through a photomask, and subsequently developed with a suitable solvent to form a fine pattern on the inorganic substrate. In the subsequent etching and impurity implantation steps, the fine pattern formed by this resist serves as a protective film, and a fine electronic circuit is formed on the inorganic substrate.
After that, the unnecessary resist film is peeled and removed.

(Prior Art and Problems) Various organic or inorganic chemicals have been studied and used for resist stripping. Examples of practically used organic materials include organic sulfonic acid-based release agents (JP-A-51-72503, etc.) and alkylene glycol-based release agents (JP-B-43-7695). Etc.),
For inorganic systems, there is a method that uses a mixture of sulfuric acid and hydrogen peroxide (piranha cleaning), a method that combines cleaning with ammonia and hydrogen peroxide, hydrochloric acid and hydrogen peroxide, and hydrofluoric acid (RCA cleaning). .

An organic stripping agent generally has a low stripping force, and exhibits almost no stripping effect particularly on a resist that has been markedly altered and hardened by a process such as selective ion implantation. Although the organic sulfonic acid-based stripper is most commonly used in organic systems, it often causes problems in resist stripping of wafers with aluminum wiring because it is corrosive to metals. It is a safety issue because it contains toxic phenol. Further, regarding the stripping of the positive type resist, it is announced that a stripping agent mainly composed of a highly polar solvent such as dimethyl sulfoxide and N, N-dimethylformamide is effective (US Pat. No. 4304681, US Patent No. 4403029, JP-A-60-66424, etc.), but these release agents have not been put to practical use in general. This is because the resist peeling force is insufficient,
This is probably because there is almost no dissolving power for ionic substances such as metal ions. Metal ions attached to the inorganic substrate for some reason penetrate into the inorganic substrate during the high temperature treatment such as the diffusion process and give a fatal defect to the performance of the semiconductor. Must be completely removed.

In order to solve the above problems, the present inventors have found that a stripping agent containing dimethylsulfoxide, water and a surfactant, and γ-
A stripping agent containing one or more selected from butyrolactone, N-methylformamide, N, N-dimethylformamide, N, N-dimethylacetamide, alcohol and / or water, and a surfactant was found and a patent application was filed.

These stripping agents exhibit a high stripping force as compared with commonly used organic stripping agents and are very effective in removing ionic substances such as metal ions.

However, even with these stripping agents, it is very difficult to strip the resist after processing by UV irradiation, reactive ion etching (RIE processing) or ion implantation.

In addition, a release agent in which water or an organic solvent is combined with an inorganic or organic base has also been announced (JP-A-53-56023, JP-A-61-292641, US Pat. No. 3813309, US Pat. (Patent No. 4518675 etc.), all have problems such as volatility of organic solvents, flammability or the need for chlorine-based solvents, stability of bases, etc. It is not practical because it is not.

On the other hand, the inorganic stripper is excellent in both the stripping force of the resist and the ability to remove ionic substances, but since it uses a high concentration of acid, alkali, and hydrogen peroxide, it is highly dangerous in terms of work safety, and further, Since hydrogen peroxide decomposes over time, there is a drawback that it is difficult to control the concentration of the stripping agent. Further, since it is highly corrosive to metals, it is not applicable to resist stripping of a wafer having aluminum wiring.

As described above, the conventional resist removers have drawbacks in both organic and inorganic removers, and no satisfactory resist remover has been obtained.
Further, there is a strong demand for an organic release agent that can sufficiently remove the resist after high energy treatment, especially from the viewpoints of handleability and liquid management.

(Means for Solving Problems) In order to solve the above problems, the present inventors have a high resist stripping force, are not corrosive to metals, and have high liquid stability and safety. As a result of earnestly studying a sufficiently practical resist remover, the present invention has been completed.

That is, the present invention is at least one selected from γ-butyrolactone, N-methylformamide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, and at least one selected from amino alcohols. And a water, and a release agent for a photoresist.

The amount of each component in the release agent of the present invention is γ with respect to the total amount of the release agent.
-Butyrolactone, N-methylformamide, N, N-dimethylformamide, N, N-dimethylacetamide, N
-The total amount of at least one selected from methylpyrrolidone must be in the range of 30 wt% or more, 1 to 50 wt% of amino alcohol and 5 to 60 wt% of water.

Examples of amino alcohols include N-n-butylethanolamine, diethylaminoethanol, 2- (2-aminoethylamino) ethanol, 2-ethylaminoethanol, N, N-dimethylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine. , Diethanolamine, di-n-butylethanolamine, triisopropanolamine, 3-amino-1-propanol, 2-methylaminoethanol, isopropanolamine, N-ethyldiethanolamine and the like.

(Function) The release agent of the present invention, during the semiconductor circuit pattern manufacturing process,
Γ-butyrolactone, N-methylformamide, N, N-dimethylformamide, N, N-Dimethylacetamide, N-methylpyrrolidone alone or a mixture thereof, or a release force which is unpredictable from the release force of aminoalcohol or water alone, shows that it is the most powerful release agent at present. A strong peeling force comparable to the so-called cleaning with a mixture of sulfuric acid and hydrogen peroxide (piranha cleaning) can be obtained. If even one component is missing from the release agent of the present invention, the release force will be significantly reduced.

The method for preparing the release agent of the present invention is not special,
It suffices to simply mix the components.

It is practically acceptable to add a surfactant to the release agent of the present invention, and by adding it, fine dust can be removed from the surface and stably dispersed in the release agent. As the surfactant, nonionic ones containing no metal ion are most preferable, and fatty acid monoglycerin ester, fatty acid polyglycol ether, fatty acid sorbitan ester, fatty acid sucrose ester, fatty acid alkanolamide,
Fatty acid polyethylene glycol condensate, fatty acid amide
Polyethylene glycol condensate, aliphatic alcohol / polyethylene glycol condensate, aliphatic amine / polyethylene glycol condensate, aliphatic mercaptan / polyethylene glycol condensate, alkylphenol / polyethylene glycol condensate, polypropylene glycol / polyethylene glycol condensate, etc., Examples of HLB are 7 or more.

The stripping agent of the present invention may also contain other miscible components. Examples thereof include alkylene glycols such as propylene glycol, alkylene glycol ethers such as propylene glycol monomethyl ether, and alcohols having 4 or more carbon atoms.

(Effect) Since the stripping agent of the present invention contains water, it exhibits excellent detergency even for ionic substances, and can completely clean the surface of the inorganic substrate after stripping.

Further, since the stripping agent of the present invention is not corrosive to ordinary metals, especially aluminum, it can be used for stripping resist from a wafer having aluminum wiring.

Furthermore, high liquid stability and safety are also features of the present invention. The components of the stripping agent of the present invention have relatively low toxicity and high flash point, and therefore are less dangerous in handling. In particular, since the release agent of the present invention contains water, it is more difficult to catch fire, which is preferable.

(Example) Hereinafter, the present invention will be described more specifically with reference to Examples.

The sample was prepared as follows. That is, a commercially available positive resist "OFPR-800 (trade name) manufactured by Tokyo Ohka Kogyo Co., Ltd." was applied to four 5-inch wafers in a thickness of about 1.5 µm, and baked at 140 ° C for 30 minutes. One of them was designated as sample No.1. The remaining 3 sheets were subjected to any one of UV irradiation, reactive ion etching (RIE treatment) and ion implantation to cure and harden the resist. These three sheets were designated as sample Nos. 2, 3, and 4, respectively. Next, samples No. 1 to No. 4 were cut into 13 × 25 mm with a diamond cutter, and these were used for a peeling test.

The cleanliness of the wafer surface after peeling was determined with a metallurgical microscope as follows.

◯: Completely peeled off Δ: Part of peeled residue left ×: Almost no peeled off
After heating in the oil bath for 15 minutes or more, the above-mentioned four kinds of samples (No. 1 to No. 4) were charged, and the peeled state after standing for 15 minutes was determined. The results are shown in Table 1.

Comparative Examples 1 to 12 The peeling performance was evaluated in the same manner as in Examples 1 to 8 except that the release agents shown in Table 1 were used. The results are shown in Table 1.

Examples 9 to 16 The release agent shown in Table 2 was placed in a 30 ml test tube in an amount of 10 ml and heated in water at 60 ° C. for 15 minutes or more.
o.4) was applied and ultrasonic waves (45 KHz, 180 W) were applied simultaneously, and the peeled state after 15 minutes was judged. The results are shown in Table 2.

Comparative Examples 13 to 24 The peeling performance was evaluated in the same manner as in Examples 9 to 16 except that the release agents shown in Table 2 were used. The results are shown in Table 2.

Claims (1)

[Claims] 1. At least one selected from γ-butyrolactone, N-methylformamide, N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone is selected from amino alcohols in an amount of 30% by weight or more. A release agent for photoresist, comprising at least 1 to 50% by weight of water and 5 to 60% by weight of water.