Dec. 3, 2020  99  US 2020/0379345 Al  (PEB) at the temperature shown in Table 7 for 60 seconds,  puddle developed in a 2.38 wt  % TMAH aqueous solution  for 30 seconds, rinsed with deionized water, and spin dried.  Using a spectroscopic film thickness measurement system  VM-2200 (Screen Semiconductor Solutions Co., Ltd.), the  resist film after development was measured for thickness in  the regions subject to different doses. E$_{0 }$ is the dose provid› ing a film thickness of 0. The slope of exposed regions where  the film thickness varied from 10 nm to 40 nm was deter› mined and reported as contrast. The results are shown in  Table 7.  [0222]  As seen from Table 5, the onium compounds used  in resist compositions of Examples are effective for forming  a film with a minimal variation of thickness, indicating that  the film functions as a resist film for micropatterning.  [0223]  Using a coater/developer system Clean Track  ACT™ 8 (Tokyo Electron Ltd.), each of the resist compo› sitions (R-06 to R-11, R-23) was spin coated onto a HMDS› primed silicon substrate of 8 inches at 1,500 rpm, and  pre-baked on a hotplate at 100°  C. for 60 seconds to form a  resist film of 50 nm thick. Thereafter, the resist film was  puddle developed in 2.38 wt % TMAH aqueous solution for  30 seconds, rinsed with deionized water, and spin dried.  Using an ellipsometer Atlas XP+ (Nanometrics Inc.), the  thickness of the resist film on the silicon substrate was  measured, with the results shown in Table 6.  [0226]  As seen from Table 7, the resist compos1t10ns  within the scope of the invention have a practically accept› able sensitivity and contrast.  [0227]  An  antireflective coating solution DUV-42 (Nissan  Chemical Industries, Ltd.) was coated onto a silicon sub› strate and baked at 200°  C. for 60 seconds to form an  antireflective coating of 61 nm thick thereon. Each of the  resist compositions (R-02, R-26, R-27, R-28) was spin  coated on the ARC, and baked on a hotplate at 100°  C. for  60 seconds to form a resist film of 50 nm thick. Using an EB  lithography system ELS-F125 (Elionix Co., Ltd., accelerat› ing voltage 125 kV), the resist film was exposed to EB so as  to write a line-and-space pattern with a size 100 nm and a  pitch 200 nm ( on-wafer size) while varying the dose from 50  µC/cm $^{2 }$at a step of 5 µC/cm 2 .  After exposure, the resist film  was baked (PEB) at the temperature shown in Table 8 for 60  seconds. The resist film was then puddle developed in a 2.38  wt % TMAH aqueous solution for 30 seconds, rinsed with  deionized water and spin dried, yielding a positive pattern.  The pattern after development was observed under an elec› tron microscope CD-SEM S-9380 (Hitachi High-Technolo› gies Corp.). Sensitivity and LWR were evaluated by the  following methods. The results are shown in Table 8.  [0224]  As seen from Table 6, the unexposed regions of the  resist compositions of Examples have a low dissolution rate  in the alkaline developer.  It is demonstrated that the resist  compositions of Examples behave as positive tone resist  relative to the alkaline developer.  [0225]  An  antireflective coating solution DUV-42 (Nissan  Chemical Industries, Ltd.) was coated onto a silicon sub› strate and baked at 200° C. for 60 seconds to form an  antireflective coating of 61 nm thick thereon. Each of the  resist compositions (R-1 to R-19, R-24) was spin coated on  the ARC, and baked on a hotplate at 100°  C. for 60 seconds  to form a resist film of 50 nm thick. By means of KrF  excimer laser scanner NSR-S206D (Nikon Corp., NA=0.86,  conventional illumination), the resist film was subjected to  open-frame exposure in a dose varying from 1 mJ/cm 2  to  200 mJ/cm$^{2 }$at a pitch of 1 mJ/cm 2 .  The resist film was baked  [0228]  As an index of sensitivity, the optimum dose Eop  (µC/cm 2 )  which provided a LIS pattern with a line width of  [5] Resist Composition Evaluation #3: Developer  Dissolution Test  Examples 4-1 to 4-6 and Comparative Example 4-1  [7] Resist Composition Evaluation #5: EB Writing  Test  Example 6-1, Comparative Example 6-1 and  Reference Examples 2-1 to 2-2  [6] Resist Composition Evaluation #4: Evaluation  of Contrast Curve  Examples 5-1 to 5-13 and Comparative Example  5-1  Evaluation of Sensitivity  Example  Comparative  Example  5-1  5-2  5-3  5-4  5-5  5-6  5-7  5-8  5-9  5-10  5-11  5-12  5-13  5-1  Resist  PEB temp.  composition  (" c.)  R-01  100  R-02  100  R-02  60  R-02  23  R-03  100  R-12  100  R-13  100  R-14  100  R-15  100  R-16  100  R-17  100  R-18  100  R-19  100  R-24  100  Eo  (mJ/cm 2 )  Contrast  23  0.8  20  0.8  38  0.6  54  0.5  40  0.5  96  1.1  42  0.5  106  0.6  50  0.4  88  0.3  115  0.8  90  0.9  49  0.5  Resist  Film thickness as  composition  developed (nm)  Example  4-1  R-06  49.8  4-2  R-07  49.3  4-3  R-08  49.5  4-4  R-09  49.3  4-5  R-10  49.1  4-6  R-11  49.5  Comparative Example  4-1  R-23  0  Resist  Film  Variation of film  composition  formation  thickness (nm)  Example  3-1  R-03  good  1.1  3-2  R-04  good  1.0  3-3  R-05  good  0.9  Comparative Example  3-1  R-22  poor  3-2  R-25  poor  TABLE 7  TABLE 5  TABLE 6 