JPS63163457A - Peeling composition for photoresist - Google Patents

Abstract

PURPOSE:To obtain a superior peeling agent for photoresist by incorporating a specified amt. of dimethyl sulfoxide and alcoholic compd. into the total amt. of the compsn. CONSTITUTION:Over 50vol.% of dimethyl sulfoxide and 5-50vol.% alcoholic compd., and >=0.01vol.% surface active agent based on the total volume of the compsn. are contained in the compsn. Suitable alcoholic compd. is satd. monohydric alcohol, e.g. butyl alcohol, amyl alcohol, hexyl alcohol, and several isomers thereof, and polyhydric alcohol, etc. Suitable surface active agent is most pref. nonionic surface active agent contg. no metal ion, e.g. fatty acid monoglycerol ester, etc. By this method, a peeling compsn. for photoresist having higher peeling effect than that exhibited by dimethyl sulfoxide or alcoholic compd. singly is provided even for a degradated and cured positive photoresist.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to photoresists used in integrated circuit manufacturing;
In particular, the present invention relates to a resist stripping composition used for removing a positive photoresist after use.

Photoresist is a photosensitive resin used in the manufacture of integrated circuits, and is used to perform operations such as etching and impurity implantation at desired locations on an inorganic substrate such as a silicon wafer. Photoresists can be roughly divided into positive types, which tend to be easily dissolved by developer in the areas exposed to light, and negative types, which tend to be the opposite.Each type is used according to its characteristics. The most common positive resist is one in which quinonediazide molecules are bonded to an alkali-soluble novolac resin via a sulfone group, and because it provides high resolution, it is used as a resist that meets the recent demands for high integration. The amount is rapidly increasing.

In the manufacturing process of integrated circuits, a resist is uniformly applied onto an inorganic substrate, exposed to light 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, this fine resist pattern becomes a protective film.
A fine electronic circuit is formed on the inorganic substrate, and then the resist film that is no longer needed is peeled off.

(Prior Art) Various organic or inorganic chemicals have been studied and used for removing resist. Examples of organic systems that are practically used include stripping agents based on organic sulfonic acids (Japanese Patent Publication No. 51-72505, etc.), and stripping agents based on alkylene glycols (Japanese Patent Publication No. 45-7695, etc.).
In addition, for inorganic systems, there is a method using 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), etc.

Organic stripping agents generally have a low stripping force and rarely exhibit stripping effects, particularly for resists that have undergone significant deterioration and hardening during processes such as selective ion implantation. Stripping agents based on organic sulfonic acids are most commonly used in organic systems, but due to their corrosive properties against metals, they often cause problems in resist stripping from wafers with aluminum wiring; It is a safety issue because it usually contains toxic phenol. In addition, regarding peeling of positive resist, dimethyl sulfoxide, N, N-
It has been announced that a composition mainly composed of a highly polar solvent such as dimethylformamide is effective (USP 430468).
1, U.S.P. 4403029, Japanese Patent Publication No. 60-664
24, etc.), these compositions have not generally been put into practical use. This is because the peeling force of the resist is insufficient, and
This is thought to be because it has almost no ability to dissolve ionic substances such as metal ions. Metal ions that have adhered to the inorganic substrate for some reason seep into the inorganic substrate during high-temperature treatment processes such as diffusion processes, causing fatal defects in the performance of integrated circuits, so these metal ions are removed during the resist stripping process. Dirt must be completely removed.

On the other hand, inorganic stripping agents have excellent resist stripping power and ability to remove ionic substances, but because they use highly concentrated acids, alkalis, and hydrogen peroxide, they pose a high risk for work safety. Since hydrogen peroxide decomposes over time, it has the disadvantage that it is difficult to control the concentration of the stripping agent. Furthermore, since it is highly corrosive to metals, it cannot be applied to resist removal from wafers with aluminum wiring.

(Problems to be Solved by the Invention) As mentioned above, conventional resist stripping agents, both organic and inorganic stripping agents, have their own drawbacks, and it is not possible to obtain a resist stripping agent that is fully satisfactory as a resist stripping agent. Not yet.

(Means for Solving the Problems) In order to solve the above problems, the present inventors have a high resist peeling force and an ionic substance dissolving power, are not corrosive to metals, and further, As a result of extensive research into highly safe resist stripping agents, we have completed the present invention.

That is, the present invention is a photoresist stripping composition characterized in that it contains at least 50 volumes of dimethyl sulfoxide and 5 to 50 volumes of alcohol, based on the total amount of the composition. The present invention also provides a photoresist stripping agent composition, which contains, in addition to the dimethyl sulfoxide and alcohol, a surfactant in an amount of 0.01 volume or more based on the total amount of the composition.

In the present invention, alcohols include saturated monohydric alcohols, such as butyl alcohol, amyl alcohol,
In addition to various isomers such as hexyl alcohol and heptyl alcohol, polyhydric alcohols such as ethylene glycol, propylene glycol, 1,3-butanediol, glycerin, and derivatives thereof such as ethylene glycol monobutyl ether and propylene Examples include glycol monomethyl ether and methoxyethanol.

The most preferred surfactant is a nonionic one that does not contain metal ions, such as fatty acid monoglycerin ester, fatty acid polyglycol ester, 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 include those with an HLB of 7 or more.

(Function) The release agent composition of the present invention exhibits an excellent peeling force that cannot be expected from the peeling force exhibited by dimethyl sulfoxide or alcohol alone, even for positive resists that have undergone deterioration and hardening during the integrated circuit manufacturing process. show.

The preferred concentration of dimethyl sulfoxide in the composition of the present invention is 60 to 90 volumes, and in this range, the strength is comparable to cleaning with a mixture of sulfuric acid and hydrogen peroxide (piranha cleaning), which is said to be the most powerful stripping agent at present. A strong peeling force can be obtained. When the concentration of dimethyl sulfoxide contained in the composition of the present invention is less than 50% by volume, a significant decrease in peel strength occurs.

Furthermore, the composition of the present invention also exhibits excellent dissolving power for ionic substances, and can completely clean the surface of an inorganic substrate after it has been peeled off. The dissolving power of ionic substances is
When the alcohol content falls below 5 volumes, it rapidly decreases.

Furthermore, since the composition of the present invention is not corrosive to ordinary metals, especially aluminum, it can also be used for resist stripping of wafers with aluminum wiring.

Furthermore, high safety is also a feature of the present invention.

The components of the compositions of the present invention are relatively non-toxic and have high flash points, thereby reducing handling hazards.

Furthermore, the composition of the present invention is liquid at room temperature and is easier to handle than pure dimethyl sulfoxide (melting point: 18.5t).

Even though integrated circuits are manufactured in strictly controlled clean rooms, it is inevitable that small particles of dust will adhere to their surfaces. When the composition of the present invention contains 0.01 volume or more of a surfactant, such dust can be removed from the surface and stably dispersed in the stripping agent, so that the surface of the inorganic substrate after stripping can be It is possible to keep it clean.

The composition of the present invention may also include a miscible fifth component.

(Example) The present invention will be described in more detail with reference to Examples below.

Examples 1 to 5 Commercially available positive resist (Tokyo Ohka Kogyo Co., Ltd. OFPR-
800) Approximately 1.5 μ on J-5 inch silicon wafer
The resist was coated to a thickness of 100° C., baked at 140 C for 30 minutes, and then subjected to ion implantation to obtain a resist that had undergone significant deterioration and hardening. Cut this wafer 13X with a diamond cutter.
It was cut into 251111 pieces and used as a sample.

Put 101 nt of the stripping agent composition into a 30 yd test tube,
After heating for more than 15 minutes in a 100C oil bath, test = 9
− Subjected to testing.

For peeling performance, a sample was placed in a heated release agent composition, and the peeling state after standing for 5 minutes was visually judged as follows, and the results are summarized in Table 1. The symbols in the table have the following meanings.

○ Completely peeled off.

△ There is some peeling residue.

× is hardly peeled off.

In addition, in the table, it is abbreviated as dimethyl sulfoxide flDMso.

= 10- Table 1 (Note) Nphthanol is a nonionic surfactant manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd.

Comparative Examples 1 to 5 Peeling performance was evaluated in the same manner as in Examples 1 to 5, and the results are shown in Table 2.

Table 2 ×1 Mixture of dodecylbenzenesulfonic acid, phenol, and chlorinated solvent

Claims (2)

[Claims] (1) A photoresist stripping composition characterized in that it contains at least 50% by volume of dimethyl sulfoxide and 5 to 50% by volume of alcohol based on the total amount of the composition. (2) 50% by volume or more of dimethyl sulfoxide and 5 to 50% by volume of alcohol based on the total amount of the composition;
A stripping agent composition for a photoresist, further comprising 0.01% by volume or more of a surfactant.