content_image/889730.jpg content_image/889732.jpg content_image/889731.jpg
<img src='content_image/889730.jpg'>

wherein a content of a group capable of decomposing by the action of an acid is expressed by a number (B) of a repeating unit having a group capable of decomposing by the action of an acid in the resin and a number (S) of a repeating unit having an alkali-soluble group which is not protected by a group capable ofleaving by the action of an acid (B/(B +S)), and the content is from 0.05 to 0.40. 

7. The radiation-sensitive composition according to claim 

6, wherein 

the resin (P) further has a repeating unit (C) represented by the following general formula (VI): 

<img src='content_image/889732.jpg'>

wherein 

each ofR$_{01}$, R$_{02 }$and R$_{03 }$independently represents a hydro- gen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an alkoxycarbonyl group, and R$_{03 }$also may represent an alkylene group and be bonded to Ar $_{1 }$to form a 5-membered ring or a 6-membered ring; 

Ar$_{1 }$ represents an aromatic ring group; and 

n represents an integer of from 1 to 4. 

8. The radiation-sensitive composition according to claim 

7, wherein 

9. The radiation-sensitive composition according to claim 6, wherein 

the resin (P) has a weight average molecular weight in a range of from 1,000 to 100,000. 

10. The radiation-sensitive composition according to claim 

6, further comprising a basic compound. 

11. The radiation-sensitive composition according to claim 6, wherein 

an electron beam, an X-ray or an EUV beam is used as an exposure light source. 

12. A pattern-forming method comprising steps of forming a resist film using the radiation-sensitive composition accord› ing to claim 6, exposing and developing. 

13. The radiation-sensitive composition according to claim 6, wherein at least one of Ar$_{2}$a to Ar$_{4}$a in formula (III-1) is an aryl group having an alkoxy group as a substituent, or at least one ofAr$_{2}$a andAr$_{3}$a in formula (III-4) is anaryl group having an alkoxy group as a substituent. 

14. The radiation-sensitive composition according to claim 6, wherein the repeating unit represented by the general for› mula (I) is selected from the group consisting of the following repeating units: 

<img src='content_image/889731.jpg'>

