PURPOSE: To obtain a Si-contg. positive photosensitive resist compsn. suitable for KrF excimer laser by constituting the compsn. of a resin having a specified chemical structure and a photoacid producing agent.

CONSTITUTION: The photosensitive resist compsn. consists of a resin having the chemical structure of formula and a photoacid producing agent. In formula, R1 is H, alkyl, phenyl, halogen, halogenated alkyl, or halogenated phenyl group and may contain Si or no Si. R2 is an alkyl, phenyl, halogenated alkyl, halogenated phenyl, or alkoxy group having at least one Si atom. In an exposed area of a photosensitive resist film of this photosensitive compsn., the double bond is opened with an acid catalyst and a hydroxyl group is added to change the polarity so that the film becomes soluble with an alkali developer. Thus, the Si-contg. positive photosensitive resist compsn. for KrF excimer laser is obtd. and this compsn. largely contributes to the production of very large scale integrated circuit devices having large steps which have been developed in these years.