Polyimide silicone, photosensitive resin composition containing the novel polyimide silicone, and method for pattern formation

A polyimide silicone having a number average molecular weight of 5,000 to 200,000, which has in the molecule a phenolic hydroxy group in which a part or all of hydrogen atoms are substituted with an acid labile group, said polyimide silicone comprises the repeating unit represented by the following general formula (1):

• wherein X is a tetravalent group at least a part of which is a tetravalent organic group represented by the following general formula (2):
• wherein R1 is independently a monovalent hydrocarbon group of 1 to 8 carbon atoms, R2 is independently a trivalent group, and n is an integer of 1 to 120 on average;
• and
• Y is a divalent organic group at least a part of which is a divalent organic group having a phenolic hydroxy group in which a part or all of hydrogen atoms are substituted with an acid labile group represented by the following general formula (3):
• wherein R3 and R4 are independently a hydrogen atom or a straight, branched, or cyclic alkyl group of 1 to 6 carbon atoms, and R5 is a straight, branched, or cyclic alkyl group of 1 to 30 carbon atoms, an aryl group of 6 to 20 carbon atoms, or an aralkyl group of 7 to 20 carbon atoms. R3 and R4, R3 and R5, or R4 and R5 may be bonded to each other to form a ring together with the carbon atom or the carbon atom and the oxygen atom to which they are bonded with the proviso that the R3, R4, and R5 involved in the formation of the ring are independently a straight or branched alkylene group of 1 to 18 carbon atoms.