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## 4) ArF Lithography Patterning Test #1: Evaluation of Hole Pattern 

## Examples 2-1 to 2-14 and Comparative Examples 2-1 to 2-10 

On a silicon wafer, a spin-on carbon film ODL-50 (Shin- Etsu Chemical Co., Ltd.) having a carbon content of 80 wt % was deposited to a thickness of 200 nm, and a silicon- containing spin-on hard mask SHB-A940 (Shin-Etsu Chemical Co., Ltd.) having a silicon content of 43 wt% was deposited thereon to a thickness of35 nm. On this substrate for trilayer process, each of the resist compositions (Inven- tive R-1 to R-14 or Comparative R-15 to R-24) was spin coated and baked on a hot plate at 100° C. for 60 seconds to form a resist film of 100 nm thick. 

Using an ArF excimer laser immersion lithography step- per (NSR-610C by Nikon Corp., NA 1.30, a 0.98/0.78, dipole opening 20 deg., azimuthally polarized illumination, dipole illumination, 6% halftone phase shift mask), the resist film was exposed through a first mask having X-axis direc- tion lines with a pitch of 80 nm and a width of 40 nm and then through a second mask having Y-axis direction lines with a pitch of 80 nm and a width of 40 nm. After exposure, the resist film was baked (PEB) at the temperature shown in Table 6 for 60 seconds and developed. Specifically, butyl acetate was injected from a development nozzle for 3 seconds while the wafer was spun at 30 rpm, which was followed by stationary puddle development for 27 seconds. Evaluation of Sensitivity 

The resist pattern thus formed was observed under an electron microscope. The optimum dose (Eop) is a dose (mJ/cm 2 ) which provides a hole pattern having a diameter of 40 nm at a pitch of 80 nm. 

Evaluation of Mask Error Factor (MEF) 

A pattern was formed by exposure in the optimum dose ( determined in the sensitivity evaluation) through a mask with the pitch fixed and the line width varied. MEP was calculated from variations of the mask line width and the pattern space width according to the following equation: 

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wherein b is a constant. A value closer to unity (1) indicates better performance. 

Evaluation of Depth-of-Focus (DOF) Margin 

The hole size printed at the optimum dose was measured is under TD-SEM (S-9380 by Hitachi Hitechnologies, Ltd.). The margin ofDOF capable of forming a resist pattern with a size of 40–5 nm was determined. A larger value indicates a smaller change of pattern size per DOF change and hence, better DOF margin. 

The results are shown in Table 6. 

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It is evident from Table 6 that when the inventive resist composition is processed by lithography and organic solvent development, a hole pattern with improved sensitivity, MEF and DOF is formed. 

