content_image/904601.jpg content_image/904602.jpg content_image/904603.jpg content_image/904604.jpg content_image/904606.jpg content_image/904605.jpg
<img src='content_image/904601.jpg'>

2. The resist composition of claim 1, wherein the pho- toacid generator is capable of generating sulfonic acid, imide acid or methide acid. 

3. The resist composition of claim 1, further comprising an organic solvent. 

4. The resist composition of claim 1 wherein the base polymer comprises recurring units having the formula (al) or recurring units having the formula (a2): 

wherein R 11 and R 13 are each independently hydrogen or 55 methyl, R 12 and R $^{14 }$are each independently an acid labile group, X is a single bond, ester group, phenylene group, naphthylene group or a C$_{1 }$-C$_{12 }$ linking group containing lactone ring, and Y is a single bond or ester group. 

5. The resist composition of claim 4, further comprising 60 a dissolution inhibitor. 

6. The resist composition of claim 4 which is a chemically amplified positive resist composition. 

7. The resist composition of claim 1 wherein the base polymer is free of an acid labile group. 

8. The resist composition of claim 7, further comprising a crosslinker. 

<img src='content_image/904602.jpg'>

<img src='content_image/904603.jpg'>

9. The resist composition of claim 7 which is a chemically amplified negative resist composition. 

10. The resist composition of claim 1 wherein the base polymer comprises recurring units of at least one type selected from the formulae (fl) to (f3): 

wherein R 51 , R 55 and R 59 each are hydrogen or methyl, R 52 is a single bond, phenylene, -O-R 63 -, or ----C(=0)-Y 1 -R 63 -, Y $^{1 }$is ---0- or-NH-, R 63 is a straight, branched or cyclic C$_{1 }$-C$_{6 }$ alkylene or alkenylene group which may contain a carbonyl, ester, ether or hydroxyl moiety, or phenylene group, 

Rs3, Rs4, Rs6, Rs7, Rss, R6o, R61, and R62 are each independently a straight, branched or cyclic C$_{1 }$-C$_{12 }$ alkyl group which may contain a carbonyl, ester or ether moiety, or a CcC$_{12 }$ aryl group, C$_{1 }$-C$_{20 }$ aralkyl group or mercaptophenyl group, 1 

A is a single bond, -A $^{0}$----C(=0)-0-, -A$^{0}$-0- or -A $^{0}$-0----C(=0)-, A0 is a straight, branched or cyclic C$_{1 }$-C$_{12 }$ alkylene group which may contain a carbonyl, ester or ether moiety, A $^{2 }$is hydrogen or trifluoromethyl, 1 

Z is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, ---O-R 64 -, or ----C(=0)› Z2-R64-, Z 2 is ---0- or -NH-, R$^{64 }$is a straight, branched or cyclic C$_{1 }$-C$_{6 }$ alkylene or alkenylene group which may contain a carbonyl, ester, ether or hydroxyl moiety, or phenylene, fluorinated phenylene or trifluo- romethyl-substituted phenylene group, 

M- is a non-nucleophilic counter ion, and fl, f2 and f3 are numbers in the range: 0sfls0.5, 0sf2s0.5, 0sf3s0.5, and 0<fl+f2+f3s0.5. 

11. The resist composition of claim 1, further comprising a surfactant. 

12. A process for forming a pattern comprising the steps of applying the resist composition of claim 1 onto a sub- strate, baking to form a resist film, exposing the resist film to high-energy radiation, and developing the exposed film in a developer. 

<img src='content_image/904604.jpg'>

<img src='content_image/904606.jpg'>

<img src='content_image/904605.jpg'>

