Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
1998-02-17
2001-11-20
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...
C430S270100, C430S326000, C430S905000, C430S910000
Reexamination Certificate
active
06319649
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention concerns a photosensitive resin composition and a method of forming a resist pattern and, more in particular, it relates to a photosensitive resin composition suitable for formation of an extremely small pattern, for example, in the manufacture of a semiconductor device, and a method of forming a resist pattern using such a photosensitive composition.
That is, the present invention concerns a photosensitive resin composition and method of forming resist image by irradiating ultraviolet light, deep ultraviolet light, X-ray and electron beam (hereinafter collectively referred to as actinic ray in the present specification), thereby forming an acid in an irradiated portion (latent images) and changing the solubility of the irradiated portion to an alkaline developer by an acid-catalyzed reaction to form a predetermined pattern, as well as a method of forming a resist pattern using the photosensitive composition.
In recent years, the requirement of small pattern with successive generation of VLSI circuits has been remarkably progressed. For example, it is required to form a pattern of less than sub-half micronmeter, like in 64 M, and 256 M.DRAM and a photosensitive composition of excellent resolution capability has been demanded.
For preparing a semiconductor integrated circuit, a reduction projecting aligner (stepper) has been used and a pattern of a size smaller than the wavelength of a light used for exposure can be resolved, by improvement in-an exposure tool or resist. However, it has not yet been obtained such a high resolution capability as capable of forming, for example, of 64 M and 256 M.DRAM device.
On the other hand, an exposure method using X-ray or electron-beam can be expected as an exposure method capable of forming a further smaller pattern than the exposure method using light and, in this case, the minimum size of the pattern formed depends on a beam diameter of X-ray or electron beam and high resolution capability can be obtained.
However, throughput in the wafer processing is important for mass production of LSI irrespective of the exposure method used and it is difficult to put a method to practical use if the productivity is low even if it can form a small pattern. For improving the productivity in the wafer processing, it is extremely important not only for the improvement of a projecting exposure device but also for making the sensitivity higher of a resist (photo-sensitive composition) to be used.
As a resist material for attaining an increased sensitivity, chemically amplified photosensitive resin compositions containing a compound showing high reactivity under the presence of an acid catalyst and an acid precursor forming an acid under the irradiation of actinic ray have been disclosed, for example, in U.S. Pat. No. 3,779,778, Japanese Patent Laid-Open No. Sho 59-45439 and Japanese Patent Laid-Open Hei 2-25850. According to the descriptions of the prior art, a compound or polymer having acetal groups, or a compound or polymer having t-butyl groups has been used as a highly reactive medium. The above-mentioned compound contains an acid decomposing group and is denatured into a compound or polymer that changes the solubility to a liquid developer, by the capability of reaction of an acid generated by the irradiation of actinic ray.
However, since the existent resist material described above has a small difference in the dissolving speed to a developer between an irradiated area and a non-irradiated area, it brings about a problem of lowering a so-called &ggr; value (lowering of resolution capability), which is a significant bar upon forming a small pattern at a high accuracy. Further, when an ingredient reacting under the presence of an acid catalyst and an alkali soluble resin are used in admixture, it results in a serious problem of separation into two inhomogeneous layers, or forming an insoluble surface inhibition layer by microphase separation of insoluble surface inhibition layer, thereby deteriorating the shape of a pattern. Further, the chemically amplified resist material also involves a problem in the stability upon treatment such as shelf life (storable period) or stability in processing.
As described above, it has been difficult in the prior art to compatibly provide high sensitivity, high resolution ability and high stability altogether.
SUMMARY OF THE INVENTION
An object of the present invention is to overcome the foregoing problems in the prior art and provide a photosensitive resin composition capable of forming a positive or negative type pattern having high sensitivity, high resolution degree and high stability, exactly at a high accuracy, as well as a method of forming resist pattern using the composition.
Another object of the present invention is to provide a photosensitive resin composition capable of forming a positive or negative type small pattern having a sufficiently high &ggr; value by development at a high accuracy using an industrially advantageous aqueous alkali solution as a liquid developer and a method of forming the resist pattern using the composition.
A further object of the present invention is to provide a chemically amplified photosensitive resin composition which is excellent in the shelf life or the stability in the processing, and free from the worry of causing troubles during development, as well as a method of forming resist pattern using the composition.
For attaining the foregoing object, a photosensitive resin composition in accordance with the present invention is based on a novel finding that the foregoing subject can be solved by adding a specified compound having a ion dissociating property to a photosensitive resin composition, and it comprises a chemically modified photosensitive resin composition containing a first compound forming an acid by irradiation of actinic ray and a second compound that changes solubility to an aqueous alkali solution with acid-catalyzed reaction, wherein a compound having a composition represented by the following general formula (1) or general formula (2) is incorporated as the ion dissociative compound, the formulae being expressed by:
where each of R
1
, R
2
, R
3
and R
4
represents hydrogen, and an alkyl group of 1 to 7 carbon atoms or an aryl group, at least one of R
1
, R
2
, R
3
and R
4
represents hydrogen, Y
1
represents chlorine, bromine, iodine, carbonate group of 1 to 7 carbon atoms or sulfonate group of 1 to 7 carbon atoms, and
where each of R
5
, R
6
and R
7
represents hydrogen, and an alkyl of 1 to 7 carbon atoms or an aryl group, Y
2
represents chlorine, bromine, iodine,or a carbonate group of 1 to 7 carbon atoms.
As the ion dissociative compound represented by the general formula (1), there can be used the ammonium salts such as tripentyl ammonium chloride, ammonium acetate, ammonium benzoate and triphenyl ammonium chloride. Further, as the ion dissociative compound represented by the general formula (2), there can be used the sulfonium, for example, salts such as trimethyl sulfonium iodide, triphenyl sulfonium bromide and ethyl dimethyl sulfonium iodide.
The ion dissociative compound functions as a stabilizer and a generator that forms acid by the irradiation of actinic ray, and a contrast enhancement material for improving the resolution capability of the resist in the photosensitive resin composition and the resist film. That is, in the chemically amplified resist material it is important to control the extent of the acid generation by the first compound upon the irradiation of the actinic ray and diffusion of the acid generated by the compound to stabilize the photosensitive resin composition and the resist film. In the present invention, since the first compound that generates the acid by the irradiation of the actinic ray and the acid generated by the compound are buffered in the photosensitive resin composition and the resist film by the ion dissociative compound shown in the general formulae (1) and (2), the control is facilitated and the stability is remarkably improved. Further, since it is
Hashimoto Masahiro
Hashimoto Michiaki
Kato Koji
Sakamizu Toshio
Shiraishi Hiroshi
Antonelli Terry Stout & Kraus LLP
Chu John S.
Hitachi , Ltd.
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