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
2000-04-28
2001-12-11
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
C430S921000
Reexamination Certificate
active
06329119
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a negative type resist composition which is suitable for lithography process for manufacturing semiconductor integrated circuits using deep ultra violet ray, including eximer laser beam, electron beam, X-rays or radiation, and the like.
In recent years, quarter-micron pattern formations have been demanded with the increase in the integration level of semi-conductor integrated circuits. Particularly, the eximer laser lithography has attracted attention because it enables producing 64 M to 256M DRAM (dynamic random access memory). As a resist suitable for such eximer laser lithography process, a resist utilizing the chemical amplification effects of an acid catalyst, generally called chemical amplification type resist, has been proposed and is putting in the practical use. For example, in the negative working chemical amplification type resist, an acid is generated from an acid generator by the action of high-energy radiation such as electromagnetic waves, and the solubility of a part exposed to a high-energy radiation of an alkali-soluble resin in an alkaline developing solution is reduced by cross-linking and hardening by the action of the generated acid and a cross-linking agent. On the other hand, the acid does not generate in a part that is not exposed to a high-energy radiation and thus the solubility in the alkaline developing solution is maintained. By such a mechanism, a negative working pattern is obtained by a series of treatments, i.e., a formation of a resist film, an irradiation for patterning and an alkaline development
The profile of a resist pattern is desirably closer to a rectangle because it has an influence on the accuracy of fine working.
Further, in the lithography using the chemical amplification type resist composition, post exposure bake is generally carried out in order to promote chain reactions using the acid generated by exposure as a catalyst. However, if sensitivity changes caused by fluctuations of post exposure bake temperature is large, the pattern dimension is susceptible to effects of temperature deflection or non-homogeneity of temperature of the bake equipment. Therefore, the sensitivity changes caused by fluctuations of post exposure bake temperature and the pattern dimensional changes at the same exposure amount are desirable to be smaller. However, in the conventional chemical amplification negative type resist, the profile at the pattern top section tended to be rounded and the sensitivity change caused by fluctuations of post exposure bake temperature tended to be large.
In the chemical amplification type resist, it is general practice to add the basic material to prevent deterioration due to inactivation of the acid associated with time passage from exposure to post exposure bake, that is, caused by standing after exposure. Attempts have been made to improve the pattern profile by selecting the basic material in this event. However, adding general basic materials which have been popularly adopted resulted in unsatisfactory effects or degraded the sensitivity or resolution, or caused sensitivity changes due to post exposure bake temperature fluctuations. Therefore, it has been desired to solve these problems.
It Is an object of the present invention to provide a negative type resist composition which has excellent pattern profile, small temperature dependency of the pattern dimensions after exposure, and achieves both excellent sensitivity and resolution. The inventors of the present invention have made extensive researches to achieve the object, and found that excellent performance can be obtained by compounding a specific basic material to the negative type resist composition comprising alkali soluble resin, acid generator, and crosslinking agent. Based on this finding, the present invention was completed.
SUMMARY OF THE INVENTION
The present invention provides a negative type resist composition comprising alkali soluble resin, acid generator, crosslinking agent, and a basic compound represented by the following formula (I)
wherein, A represents bivalent aliphatic hydrocarbon residue which may be optionally interrupted by imino group, sulfide group, or disulfide group, X represents nitrogen atom or C(NH
2
), and R
1
and R
2
independently represent hydrogen or alkyl.
PREFERRED EMBODIMENT OF THE INVENTION
The composition according to the present invention comprises the basic compound represented by Formula (I) above in addition to alkali soluble resin, acid generator, and crosslinking agent. Only one kind of compounds included in the definition of Formula (I) may be contained or as required, two or more kinds of compounds included in the definition may be used together. By comprising the specific basic compound, effects of improved resolution and better pattern profile have been achieved, as compared to those in which the conventional basic compound is used, and the sensitivity change caused by temperature fluctuations of post exposure bake can be reduced. Furthermore, the basic compound of Formula (I) can exhibit the effective performance as mentioned above at a smaller consumption amount than those which have been conventionally used for the negative type resist.
In Formula (I), A represents bivalent aliphatic hydrocarbon residue which may be interrupted by imino group, sulfide group or disulfide group. The hydrocarbon residue may be saturated, that is, alkylene, or unsaturated, for example, alkenylene. Imino group (—NH
2
—) may optionally be interposed in the hydrocarbon residue. The imino may exist in plurality in A, but in general, one imino exists. The aliphatic hydrocarbon residue represented by A has a total of 1 to 10 carbons including the case with imino interposed. When A consists of only carbon atom and hydrogen atom, the number of carbons is preferably between 1 and 4. If the number of carbons is 2 or more, they may be either of normal chain or branched, although the linear type, such as linear alkylene or linear alkenylene, is preferable. That is, linear alkylene having 2 to 4 carbon atoms, linear alkenylene having 2 to 4 carbon atoms and the like are preferable. If A is bivalent aliphatic hydrocarbon residue interrupted with imino, the number of total carbons is preferably between 2 and 6. In this case, too, the group consisting of carbon atom and hydrogen atom existing on both side of imino group may be either of normal chain or branched, if the number of carbons is two or more, respectively. Iminobisalkylene is more preferred as A, and particularly, iminobisalkylene having 2 to 6 carbon atoms is preferred.
A is preferably bivalent aliphatic hydrocarbon residue which may be optionally interrupted by imino group. When this is used, dimensional difference or profile difference tend to be hardly generated between the line and space pattern and isolated pattern.
Specific examples of A include methylene, ethylene. vinylene, trimethylene, tetramethylene, iminobismethylene, sulfide and disulfide.
The linked group A may be positioned at any of 2-position, 3-position, or 4-position on the six-membered ring with respect to X in Formula (I). Preferably, it positioned at 3-position or 4-position of both six-membered rings, respectively. The preferable structure of the compound of the formula (I) is represented by the following Formula (Ia):
wherein, A, X, R
1
and R
2
are the same as defined above, and the marks, “]” and “[” indicate that A is positioned on 3-position, or 4-position on the six-membered rings with respect to X.
In Formula (I), R
1
and R
2
, which are the same to or different from each other, are hydrogen or alkyl. The alkyl may have 1 to 6 carbons. If the number of carbons is 3 or more, it may be either normal chain or branched. Furthermore. X represents nitrogen atom or C(NH
2
). Therefore, the basic compound represented by Formula (I) may be classified into pyridine derivative represented by the following Formula (Ib) and aniline derivative represented by the following Formula (Ic):
wherein, A, R
1
and R
2
are the same as defined abov
Kusumoto Takehiro
Shinada Masanori
Suetsugu Masumi
Takeyama Naoki
Ashton Rosemary
Birch & Stewart Kolasch & Birch, LLP
Sumitomo Chemical Company Limited
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