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ArF Exposure Evaluation 

Spin-on carbon film ODL-102, manufactured by Shin› Etsu Chemical Co., Ltd., was formed on a silicon wafer with a film thickness of 200 nm, and silicon-containing spin-on hard mask SHB-A940 was formed thereon with a film thickness of 35 nm to obtain a substrate for a tri-layer process. On this substrate, the resist composition prepared with the composition shown in Table 1 (Examples 1, 2, and Comparative Example 1) was applied by spin coating and then baked with a hot plate at a temperature shown in Table 2 for 60 seconds to form a resist film 90 nm thick. 

These films were exposed to light by anArF excimer laser liquid immersion scanner (NSR-610C, manufactured by Nikon Corporation, NA=l.30, a=0.98/0.78, dipole opening 20°, Azimuthally polarized illumination, 6% halftone phase shift mask) with various exposure dose. After exposure, baking (PEB) was performed at a temperature shown in Table 2 by a manual hot plate to which the air containing 25 g of moisture per kilogram of dry air at 40° C. (50% humidity) was supplied with a flow rate of 2 Umin by a precisely controlled humidity-supplying apparatus SRG-1 R› AS, manufactured by Daiichikagaku Inc. After PEB for 60 seconds, puddle development was carried out with a devel› oper of n-butyl acetate for 30 seconds to form a 40-nm line and space pattern. Sensitivity at this time and line width roughness (LWR) after development were measured with a length measuring SEM (CG-4000, manufactured by Hitachi High-Technologies Corp.). The result is given in Table 2. 

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Electron Beam Lithography Evaluation 

For lithography evaluation, the resist composition pre› pared with the composition shown in Table 1 (Examples 3 to 6 and Comparative Example 2) was applied on a 6-inch diameter Si substrate subjected to HMDS (hexamethyldisi› lazane) vapor prime, by spin coating with clean track Mark 

5 (manufactured by Tokyo Electron, Ltd.). Then, the com- position was pre-baked on a hot plate at 110° C. for 60 seconds to form a resist film with a thickness of 100 nm. To this was drawn in a vacuum chamber with HL-S00D (manu› factured by Hitachi, Ltd.) with a HV voltage of 50 keV. 

After drawing, PEB was performed at a temperature shown in Table 3, by a manual hot plate to which the air containing 25 g of moisture per kilogram of dry air at 40° C. (50% humidity) was supplied with a flow rate of2 Umin by a precisely controlled humidity-supplying apparatus SRG› lR-AS, manufactured by Daiichikagaku Inc. Then, puddle development was carried out with a 2.38 mass % TMAH aqueous solution for 30 seconds to obtain a positive pattern. 

The obtained resist pattern was evaluated in the following manner. 

A minimum dimension at an exposure dose which allows a 120-nm line and space pattern of 1:1 resolution was defined as resolution, and line width roughness (LWR) of the 120-nm LS pattern was measured by SEM. 

Table 3 shows the resist compositions, results of sensi› tivity in EB exposure, resolution, and LWR thereof. 

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The results of Tables 2 and 3 demonstrate that Examples to 6, which contain the polymer compound having the repeating unit substituted with the acid-labile groups shown by the general formulae (1-1) to (1-5), had appropriate resolution, sensitivity and LWR. 

In addition, when the polymer-type acid generator was copolymerized (Examples 4 to 6), LWR property was more improved than Example 3, which contains no polymer-type acid generator. This indicates that the polymer compound used in the inventive resist composition exhibited very excellent resolution and small LWR by synergism due to copolymerization with the acid generator. 

