Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
1999-04-07
2001-03-27
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S192000, C430S331000
Reexamination Certificate
active
06207356
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for the pattern-processing of a photosensitive resin composition for obtaining a scum-free, high-resolution pattern.
2. Prior Art
In a semiconductor industry, a photosensitive resin such as a photoresist, a photosensitive polyimide or the like has recently been often used in the preparation of a very fine circuit such as IC, LSI or the like or as an insulating film or protective film in a package requiring processing. The characteristic feature of the photosensitive resin consists in that a high precision resin pattern can be obtained by a relatively simple apparatus. In particular, a positive photoresist comprising as a base a phenol novolak resin using a diazoquinone or the like as a photosensitive agent enables the formation of a pattern excellent in resolution because it does not swell during developing. In addition, since the developer is an alkaline aqueous solution, the positive photoresist is excellent in an aspect of safety. As discussed above, the photosensitive resin has many features, and hence, has been often used in the production of fine circuits and the like of the above semiconductor. On the other hand, in a photosensitive, heat-resistant resin such as a photosensitive polyimide which is used in the insulating film or protective film of a semiconductor, a positive type photosensitive, heat resistant resin having such features as high resolution, environmental pollution-free developer and the like has been developed similarly to the photoresist (see, for example, JP-A-64-60630, JP-B-1-46862 and the like) and has attracted attention as a resin for insulating film or protective film of a highly integrated semiconductor.
Most of the positive photosensitive resin compositions are composed of a combination of an alkali soluble polymer with the above-mentioned diazoquinone compound as a photosensitive agent. In the unexposed portions, these quinonediazide compounds are insoluble in an alkaline aqueous solution; however, upon exposure, they cause a chemical reaction to become soluble in an alkaline aqueous solution. Accordingly, utilizing the difference in solubility between the exposed portion and the unexposed portion, the exposed portion is removed by an alkaline aqueous solution, whereby it becomes possible to prepare a coating film pattern composed of only the unexposed portion.
The alkaline aqueous solution used as a developer is generally an aqueous solution of tetramethylammonium hydroxide (referred to hereinafter as TMAH). When a photoresist comprising as a base a conventional phenol novolak resin is developed, a good development can be effected using an aqueous solution of this TMAH. However, in the case of a photosensitive resin composition comprising a polybenzoxazole precursor as stated in JP-B-1-46862 as a base, there is such a disadvantage that an undeveloped portion (scum) remains in the exposed portion which should be completely removed to avoid deterioration of the resolution.
SUMMARY OF THE INVENTION
An object of this invention is to provide a method for the pattern-processing of a photosensitive resin composition giving a high resolution without causing a scum which has been caused in the conventional pattern processing.
Other objects and advantages of this invention will become apparent from the following description.
According to this invention, there is provided a method for the pattern-processing of a photosensitive resin composition, which comprises coating a positive photosensitive resin composition comprising a polyamide represented by the following formula (1) and a diazoquinone compound on a substrate, subjecting the same to prebaking and then to irradiation with a light and thereafter dissolving the exposed portions in an alkaline aqueous solution containing an alkylbenzenesulfonic acid to remove the same, thereby obtaining a pattern:
wherein X is a tetravalent aromatic group; Y is a divalent aromatic group; Z is
in which R
1
and R
2
are divalent organic groups and R
3
and R
4
are monovalent organic groups; a and b are mole fractions; a+b=100 mole %; a=60.0-100 mole %; b=0-40.0 mole % and n=2-500.
DETAILED DESCRIPTION OF THE INVENTION
The polyamide represented by the formula (1) is composed of a bisaminophenol having the structure of X and a dicarboxylic acid having the structure of Y and when this polyamide is heated at about 300-400° C., ring closure reaction is caused to convert the polyamide to a heat-resistant resin called polybenzoxazole. In general, a positive photosensitive resin composition is developed with an aqueous alkali solution. For example, a photoresist can be developed because the phenol novolak resin which is the base of the photoresist has phenolic hydroxyl groups. Similarly, a positive photosensitive resin comprising as a base a polyamide represented by the formula (1) can also be developed because the bisaminophenol having the structure of X has phenolic hydroxyl groups. However, this photosensitive resin is inferior in developability to the photoresist comprising as the base a phenol novolak resin and causes scum in the exposed portion, whereby the resolution is deteriorated.
This is considered to be because while the phenol novolak resin contains one hydroxyl group per one benzene ring, the polyamide represented by the formula (1) contains a hydroxyl group only in the amine moiety. In the case of a polyamide formed by replacing a part of the bisaminophenol having the structure of X by the silicone diamine having the structure of Z of the formula (1) for the purpose of improving the adhesiveness, the solubility of the resin becomes lower, and hence, more scum is caused and the resolution becomes very bad. However, when the resin composition is processed with the aqueous alkali solution containing an alkylbenzene-sulfonic acid of this invention, the scum is not caused at all. Although the cause has not been clarified, this is considered to be because the affinity between the resin and the developer is improved by the alkylbenzene-sulfonic acid.
In the polyamide (1) of this invention, X includes, for example,
wherein A represents —CH
2
—, —O—, —S—, —SO
2
, —CO—, —NHCO— or —C(CF
3
)
2
—; and the like, but is not limited thereto.
In the formula (1), Y includes, for example,
wherein A represents —CH
2
—, —O—, —S—, —SO
2
—, —CO—, —NHCO— or —C(CF
3
)
2
—; and the like, but is not limited thereto.
Moreover, in the formula (1), Z includes, for example,
and the like, but is not limited thereto.
Z in the formula (1) is used when the adhesiveness to a substrate such as a silicon wafer is required, and can be used in such an amount that the proportion b is at most 40.0 mole %. When the proportion b exceeds 40 mole %, the solubility of the resin becomes very low and even when the pattern-processing method of this invention is used scum is caused and the pattern-processing becomes impossible.
Incidentally, when these X, Y and Z are used, each of them may be alone or in admixture of two or more.
The surfactant used in this invention is an alkylbenzenesulfonic acid. Dodecylbenzenesulfonic acid is a typical example. However, the surfactant is not limited thereto. The surfactants containing a salt such as alkylbenzenesulfonic acid salt and the like contain undesirably large amounts of metallic impurities, and such impurities cause a corrosion of the aluminum pad of the semi-conductor, etc. and hence such salts are not preferable. The content of metal ion in the whole alkaline aqueous solution should be kept to no more than 0.001 to 1 ppm, and when the content exceeds 1 ppm, corrosion of semi-conductor chip, etc. occurs. Therefore, an alkylbenzenesulfonic acid is preferred as a surfactant.
The amount of the alkylbenzenesulfonic acid contained in the alkaline aqueous solution which is the developer of this invention is preferably 0.1 to 10% by weight based on the total weight of the alkaline aqueous solution. When the amount is less than 0.1% by weight, scum tends to be caused and when the amount is more t
Banba Toshio
Takeda Toshiro
Browdy and Neimark
Chu John S.
Sumitomo Bakelite Company Limited
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