Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2001-06-18
2003-11-11
Ashton, Rosemary (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S905000
Reexamination Certificate
active
06645692
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a photoresist composition suitable for lithography utilizing a high energy radiation such as far ultraviolet rays (including excimer laser, or the like), an electron beam, X-rays or a radiation.
In recent years, with the increase in the higher integration of integrated circuits (IC), a pattern formation of a quarter of a micron has been in demand. In response to this demand, excimer laser lithography that allows the fabrication of 64M DRAMs and 256M DRAMs has drawn attention. As a resist suitable for this excimer laser lithography process, a so-called chemical amplifying type photoresist that utilizes an acid catalyst and a chemical amplifying effect has been progressively adopted. The chemical amplifying type photoresist changes its solubility to an alkaline developer in the irradiated portion through a reaction using the acid generated from the acid generator by the radiation, as a catalyst, thereby gives a positive type or a negative type pattern.
Then, under the circumstances where the miniaturization of process dimensions is progressing rapidly corresponding to the increase in the degree of integration of semiconductor integrated circuits, the demand for the minute processing related to the above described chemical amplifying type resist has greatly increased. In the case of a chemical amplifying type positive resist, it is generally said that the larger the ratio of acid unstable groups to the resin in the resist composition (protection ratio), the greater the contrast and the greater the resolution. When the protection ratio of the resin increases, however, the hydrophobic property of the resist coating film increases and wettability of the developer deteriorates so that development deficiency occurs very often. The faulty development will damage circuit patterns in the minute processing steps and provide a factor that decreases the yield of manufacture of semiconductors.
The object of the present invention is to provide a photoresist composition that does not allow development deficiency to occur while, at the same time, maintaining excellent resist performances such as sensitivity, resolution, heat resistance, remaining film thickness, coatability and pattern profile.
The present inventor has conducted extensive studies in order to achieve the above object, and, as the result, has found that a resist with reduced development deficiency can be obtained by incorporating a specific surface active agent having fluorine atom(s) into photoresist composition.
SUMMARY OF THE INVENTION
The present invention provides a photoresist composition excellent in practical use which comprises a binder component, an acid generator and a surface active agent containing fluorine atom(s).
EMBODIMENT OF THE INVENTION
The present invention is characterized by using a fluorine-containing surface active agent as a development deficiency suppression agent. Among fluorine-containing surface active agents a polymer containing a fluorinated alkyl group and a silicone group is preferably used. Specifically, a fluorine-containing surface active agent represented in the following formula (I) can be mentioned:
wherein R
1
to R
5
independently represent hydrogen atom, a fluorine atom, an alkyl group having from 1 to 4 carbon atoms or a cyclo-alkyl group having from 5 to 7 carbon atoms, respectively, and n is an integer from 10 to 10000.
Here, examples of the alkyl group having from 1 to 4 carbon atoms include methyl, ethyl, propyl, i-propyl, butyl, i-butyl, and sec-butyl. Examples of the cyclo-alkyl group having from 5 to 7 carbon atoms include cyclopentyl, cyclohexyl, and cycloheptyl. Further, n is preferably, from 100 to 1000. A commercially available fluorine-containing surface active agent such as “FS-1265” (made by Toray Silicone Co. Ltd. ) can be used. One kind of the fluorine-containing surface active agent may be used singly, or two or more kinds may be used in combination in the photoresist composition of the present invention.
Although the content of the surface active agent in the composition of the present invention can be appropriately selected according to the kinds of fluorine-containing surface active agent and the kinds of photoresist compositions, 1 ppm to 100 ppm based on the total weight of the composition and, preferably, 10 ppm to 100 ppm, is usually acceptable in the composition. When the content is too large, decrease in the effect for reducing development deficiency tends to occur. In the case when the content is too small, it leads to an insufficient reduction of development deficiency whereby an uneven application is generated. Furthermore, a silicon-containing surface active agent or a hydrocarbon-containing surface active agent may be used in addition to the fluorine-containing surface active agent of the present invention as long as the effect of the present invention is not adversely affected.
In addition, as for a binder component in the present invention, generally an alkaline soluble resin or a resin that can become alkaline soluble is utilized. The acid generator generates acid by irradiation and the chemical amplifying type positive resist utilizes the catalytic function of the generated acid. That is to say, the acid generated in the irradiated portion diffuses in the successive heat processing (post exposure bake) and cleaves the protection groups of the resin, etc., thereby converting the irradiated portion into alkaline soluble. Chemical amplifying type positive resists include, for example, following types:
(1) a chemical amplifying type positive resist which comprises a binder resin which is alkaline soluble; an acid generator; and a dissolution inhibitor which has a protection group cleavable due to the acid and has a dissolving suppression function to the alkaline soluble binder resin but loses the dissolving suppression function after the above protection group is cleaved due to the acid.
(2) a chemical amplifying type positive resist which comprises an acid generator; and a binder resin which has a protection group cleavable due to acid, and is insoluble or difficult to be dissolved in alkaline solution, but converts into an alkaline soluble substance after the above described protection group is cleaved due to acid.
In addition, the chemical amplifying type photoresist of negative type generally contains a alkaline soluble binder resin and a cross-linking agent and a radiation sensitive component. In such a negative resist acid generated in an irradiated portion diffuses through the successive heat processing and acts on the cross-linking agent so as to cure and convert the binder resin in the irradiated portion into a non-alkaline soluble material.
Examples of the binder resin which is inherently alkaline soluble and used in the chemical amplifying type positive resist include an alkaline soluble resin having a phenol structure and an alkaline soluble resin that has (meth)acrylate structure and has an alicyclic ring and carboxyl groups on the alcohol side of the ester. Specific example thereof include a polyvinylphenol resin, poly-isopropenylphenol resin, a polyvinylphenol resin or poly-isopropenylphenol resin wherein a portion of the hydroxide group is alkyl-etherificated, a copolymer resin of vinylphenol or iso-propenyl phenol with other polymerizable unsaturated compound, a polymer of an alicyclic ester of (meth)acrylic acid having carboxyl group(s) in the alicyclic ring thereof, and a copolymer of an alicyclic ester of (meth)acrylic acid and (meth)acrylic acid.
When such a resin being inherently alkaline soluble is used as a binder component, a dissolution inhibitor is used. The dissolution inhibitor can be a compound of which the phenolic hydroxide group is protected with a group that has a dissolving suppression function against an alkaline developer and that is cleaved by the acid. Examples of the group which is cleaved by an acid include the tert-butoxycarbonyl group can be cited and this is replaced with a hydrogen in a phenolic hydroxide group. The dissolution inhibitor includes, f
Ashton Rosemary
Sumitomo Chemical Company Limited
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