Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2000-01-10
2001-04-17
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S191000, C430S192000, C430S193000
Reexamination Certificate
active
06218069
ABSTRACT:
BACKGROUND OF THE INVENTION
The majority of resist compositions currently used for the preparation of semiconductor devices are positive working resist compositions. Negative working resist compositions using cyclized rubber are difficult to increase resolution because organic solvents used as the developer cause significant swelling. By contrast, positive working resist compositions are developed with aqueous base solutions, which eliminates the swelling problem and affords superior resolution. The positive working resist compositions can thus accommodate for the desired high integration of semiconductor devices.
Most of positive resist compositions are comprised of an alkali-soluble phenolic resin and a photosensitive agent such as quinonediazidosulfonic acid ester. These positive resist compositions suffer from the precipitation of foreign matter during long-term storage because many photosensitive agents are insufficiently soluble in solvents.
To eliminate the above drawback, JP-B 45-9610 proposes a photosensitive resin having quinonediazido-sulfonic acid groups directly incorporated in an alkali-soluble resin at hydroxyl groups thereon. Since this photosensitive resin is prepared using a basic catalyst for condensation such as triethylamine, a salt of the catalyst such as the hydrochloride salt of triethylamine forms as a by-product. If a photosensitive resin composition is formulated using the photosensitive resin with the salt left therein, the use of the composition entails the problem that the salt can cause corrosion of aluminum or other metal substrates.
For preventing any loss of characteristics of the photosensitive resin by the presence of the basic catalyst itself and the salt thereof by-produced, it is proposed in JP-A 63-236030 to purify the photosensitive resin product to remove the basic catalyst and the salt thereof. This purifying and removal step is complex, cumbersome and industrially disadvantageous.
It is known from JP-A 63-237053, 9-230592 and 9-236923 that the presence of certain basic compounds in positive photoresist compositions is effective for improving the shelf stability and adhesion to substrates of the resist compositions. This suggests that if not only the salt of the basic catalyst, but the residual base are removed by the above-mentioned purifying and removal step so that only an extremely reduced amount of residual base is available, there can arise a problem that the adhesion to substrates of the resist composition, which is one of key functions, is aggravated.
SUMMARY OF THE INVENTION
An object of the invention is to provide a novel and improved photosensitive resin composition which is superior in sensitivity stability, does not cause corrosion of metal substrates, and has improved adhesion to substrates. Another object of the invention is to provide a process for preparing such an improved photosensitive resin composition.
The invention is predicated on the following discovery. A novolac resin comprising recurring units of the general structural formula (3) shown below is reacted with 1,2-naphthoquinonediazido-5-sulfonic acid chloride to introduce a specific proportion of 1,2-naphthoquinone-diazido-5-sulfonic acid residues into the novolac resin at its hydroxyl groups, thereby forming a photosensitive resin comprising recurring units of the general structural formula (1) shown below and having a weight average molecular weight of 1,300 to 11,000. If this reaction is effected in an organic solvent in the presence of a tertiary amine compound of the general structural formula (2) shown below, then a subsequent simple separation step can readily reduce the concentration of a salt of the tertiary amine compound. Since the tertiary amine compound is partially left in the resulting photosensitive resin, a desirable photosensitive resin composition is obtained without a need to add an extra base. The composition thus obtained has an appropriate concentration of the tertiary amine compound, but a minimized concentration of the hydrochloride salt of the tertiary amine compound co-present therewith, so that the composition is improved in sensitivity stability and free of the risk of causing the corrosion of metal substrates. While acting as a dehydrochlorination condensation reaction catalyst during the reaction, the specific tertiary amine compound of formula (2) also exerts a surface activating effect in the reaction system, enabling more uniform introduction of photosensitive groups into the novolac resin. This leads to a satisfactory resist composition which has minimized such problems as the formation of scum upon development. The composition comprising the photosensitive resin as a main component and the tertiary amine compound of formula (2) is improved in storage stability, substrate adhesion and heat resistance, and lends itself to the fabrication of electronic parts such as semiconductor devices, display devices (e.g., liquid crystal devices), and magnetic heads.
Accordingly, the present invention in a first aspect provides a photosensitive resin composition comprising a photosensitive resin comprising recurring units of the following general structural formula (1) and having a weight average molecular weight of 1,300 to 11,000, and a tertiary amine compound of the following general structural formula (2).
In a second aspect, the invention provides a process for preparing a photosensitive resin composition, comprising the step of reacting a novolac resin comprising recurring units of the following general structural formula (3) and having a weight average molecular weight of 1,000 to 10,000 with 1,2-naphthoquinonediazido-5-sulfonic acid chloride in an organic solvent in the presence of a tertiary amine compound of the following general structural formula (2).
Herein, R is hydrogen or a 1,2-naphthoquinonediazido-5-sulfonic acid residue, the content of 1,2-naphthoquinone-diazido-5-sulfonic acid residue in R being 3 to 27 mol %, and m is a number from 0 to 3.
Herein, X is an alkyl, aryl or aralkyl group of 6 to 20 carbon atoms, Y and Z each are an alkyl group of 1 to 20 carbon atoms.
Herein, m is a number from 0 to 3.
According to the invention, a novolac resin comprising recurring units of formula (3) is reacted with 1,2-naphthoquinonediazido-5-sulfonic acid chloride using a tertiary amine compound of formula (2) as a basic catalyst. Then, by effecting a simple separation step on the reaction solution, the concentration of the salt of the tertiary amine compound remaining in the reaction solution can be reduced to a sufficient level to eliminate any detrimental influence such as the corrosion of metal substrates and to improve such performance factors as sensitivity stability and substrate adhesion. Without a need for cumbersome repetitive separation steps and an additional step of separately adding an extra basic compound, the invention is successful in producing through simple steps and in an industrially advantageous manner a photosensitive resin composition which has superior sensitivity stability and improved adhesion to substrates, and does not cause corrosion of metal substrates.
REFERENCES:
patent: 5279918 (1994-01-01), Nishi et al.
patent: 5422221 (1995-06-01), Okazaki et al.
patent: 5679495 (1997-10-01), Yamachika et al.
patent: 45-9610 (1970-04-01), None
patent: 63-236030 (1988-09-01), None
patent: 63-237053 (1988-10-01), None
patent: 9-230592 (1997-09-01), None
patent: 9-236923 (1997-09-01), None
English abstract of JP-B 45-9610.
English abstract of JP-A 63-236030.
English abstract of JP-A 63-237053.
English abstract of JP-A 9-230592.
English abstract of JP-A 9-236923.
Furihata Tomoyoshi
Kato Hideto
Okazaki Satoshi
Chu John S.
Millen White Zelano & Branigan P.C.
Shin-Etsu Chemical Co. , Ltd.
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