Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2000-05-08
2004-04-20
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, C430S193000, C430S270100
Reexamination Certificate
active
06723484
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a photosensitive resin composition which can be used for the interlayer dielectrics of semiconductor devices and for buffer coat films, &agr;-ray shielding films and the like, and which can form patterns by exposing to actinic radiation and dissolving away the exposed regions with aqueous alkali solution.
TECHNICAL BACKGROUND
Heat-resistant resins such as polyimides are employed in the semiconductor field to form interlayer dielectrics, buffer coat films, &agr;-ray shielding films and the like. In using a polyimide in such applications, patterning of the polyimide film is necessary for the purpose of through hole formation and the like. For example, a solution of the polyamic acid, which is the polyimide precursor, is applied to the substrate, and then converted to the polyimide by heat treatment, after which a positive photoresist relief pattern is formed on the polyimide film and, with this as a mask, patterning is carried out by selective etching of the polyimide film by means of a hydrazine etching agent. However, this method has the problem that, as well as the process being complex since it includes the photoresist application and removal steps, etc, dimensional accuracy is lowered because of side etching. For such reasons, photosensitive resin compositions have been investigated which are heat-resistant resins, or precursors which can be converted to heat-resistant resins by means of a heat treatment or the like, and which themselves can undergo pattern processing.
For photosensitive resin compositions to have a pattern accuracy enabling them to be employed in passivation layer pattern formation, a method has been investigated whereby first of all patterning and curing of the photosensitive resin precursor composition is carried out on the passivation layer prior to pattern formation and then, with this pattern as a mask, dry etching of the underlying passivation layer is carried out (the one mask process). In accordance with this method, it is possible to shorten the process required in passivation layer pattern formation, leading to a reduction in costs.
When using a photosensitive resin composition, normally application and drying on the substrate are performed in the solution state, and irradiation with active light rays is performed through a mask. As negative-working photosensitive resin precursor compositions where the exposed regions are left following the developing, there are known compositions where a substance having carbon-carbon double bond which is demeriziable or polymerizable by actinic radiation and an amino group or quaternized salt thereof are added to a polyamic acid (JP-B-59-52822). compositions where an acrylamide is added to the polyamic acid (JP-A-3-170555) and compositions where a polyimide precursor with a carbon-carbon double bond, a specified oxime compound and a sensitising agent are incorporated (JP-A-61-118423). However, there is the problem that changing over from a conventional non photosensitive resin composition patterning process using a positive-working photoresist to a process using a negative-working photosensitive resin composition requires a change in the exposure device mask and a change in the developing equipment. Furthermore, these negative-working photosensitive resin compositions employ organic solvents in the developing, but from the point of view of preventing environmental pollution and improving the working environment, a photosensitive material which can be developed with an aqueous developer liquid instead of an organic developer liquid is desirable. For these reasons, alkali-developable positive-working photosensitive resin compositions are being investigated.
As known examples of positive-working photosensitive resin compositions where the exposed regions are dissolved away by developing with an aqueous alkali solution, there are the polyimide precursors where o-nitrobenzyl groups have been introduced by ester bonds (JP-A-60-37550), the composition where an o-quinone diazide compound is mixed into a polyamic acid ester (JP-A-2-181149), the composition where an o-quinone diazide compound is mixed with a polyamic acid or polyamic acid ester which has a phenolic hydroxyl group (JP-A-3-115461), the composition where an o-quinone diazlde compound is mixed with a polyimide which has a phenolic hydroxyl group (JP-3-177455), and the composition where an o-quinone diazide compound is mixed with a polyhydroxyamide (JP-B-1-46862) .
However. the polyimide precursors with o-nitrobenzyl groups introduced by means of ester bonds have the problem that the sensitising wavelengths are mainly below 300 nm and the sensitivity is low. In the case where an o-quinone diazide compound is mixed into the polyamic acid ester, the rate of dissolution by the alkali developer is low, so the sensitivity is low and the developing time is lengthy. In the case where an o-quinone diazide compound is added to a polyamic acid with a phenolic hydroxyl group, the solubility in the alkali developer is too great, so there is the problem that only dilute developer liquid can be employed and, since the unexposed regions are swollen by the developer liquid, fine patterning is difficult. Where an o-quinone diazide compound is mixed with a or polyimide with a phenolic hydroxyl group, the dissolution rate in the alkali developer is improved but there is the problem that further adjustment of the dissolution rate is difficult Where an o-quinone diazide compound is mixed with a polyhydroxyamide, the dissolution rate in the alkali developer is improved but there is the problem that change to the polymer composition is required for further adjustment in the dissolution rate. The present invention has been made in view of these various problems of the prior art, and it has as its objective to offer a photosensitive resin composition where adjustment of the dissolution time in the aqueous alkali solution is possible and, furthermore, where the polymer transparency is high at the exposure wavelengths and which has high sensitivity.
DISCLOSURE OF THE INVENTION
The present invention is a positive-working photosensitive resin composition which is characterized in that it contains (a) polymer in which the chief component comprises structural units of the kind where the bonding between structural units is represented by general formula (1) and (b) photoacid generator, and which can form a pattern by light irradiation and subsequent developing, and the total carboxyl groups contained in 1 g of said polymer is from 0.02 to 2.0 mmol.
(R
1
is an organic group of valency from 3 to 8 having at least 2 carbon atoms, R
2
is an organic group of valency from 2 to 6 having at least 2 carbon atoms, R
3
is hydrogen or an organic group with from 1 to 10 carbons but it is not all hydrogen. n is an integer of value from 3 to 100,000, m is 1 or 2, p and q are integers of value from 0 to 4 and p+q>0).
Optimum Form for Practising the Invention
In the present invention, the polymer represented by general formula (1) is preferably one which can form a polymer with imide rings, oxazole rings or other cyclic structures by heating or by means of a suitable catalyst. By forming cyclic structures, the heat resistance and solvent resistance are markedly enhanced. The polymer in which structural units represented by aforesaid general formula (1) are the chief component preferably has hydroxyl groups. In such circumstances, because of the presence of the hydroxyl groups, the solubility in aqueous alkali solution is better than that of a polyamic acid which does not have hydroxyl groups. In particular, from amongst hydroxyl groups, phenolic hydroxyl groups are preferred in terms of their solubility in aqueous alkali solution.
The residual group which constitutes R
1
in general formula (1) denotes an acid structural component, and this acid component is preferably a C
2
to C
60
trivalent to octavalent group containing an aromatic ring and having from one to four hydroxyl groups. Where R
1
does not contain hydroxyl groups, desirably the R
Okamoto Naoyo
Okuda Ryoji
Tomikawa Masao
Yoshida Satoshi
Chu John S.
Morrison & Foerster / LLP
Toray Industries Inc.
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