Positive photoresist composition

A positive photoresist composition comprising the components of:

• (a) a resin which decomposes by the action of an acid, thereby having an increased solubility in an alkali developer;
• and
• (b) at least one compound which is represented by the following formula (1) and generates an acid by exposure to active rays or radiation, and at least one compound which is represented by the following formula (2) and generates an acid by exposure to active rays or radiation:
• 21
• wherein R1 and R2 each independently represents one of an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group and a cycloalkenyl group each of which has 1 to 16 carbon atoms and may have at least one substituent, an aryl group and a heteroaryl group each of which may have at least one substituent and a cyano group,
• at least one of R1 and R2 may be bonded to at least one of R1 and R2 of another compound represented by the formula (1) via one of an alkylene chain, an alkenylene chain and an alkynylene chain each of which has 2 to 8 carbon atoms and may have at least one substituent and a connecting chain comprising one of phenylene, furylene and thienylene each of which may have at least one substituent and a connecting chain comprising one of —O—, —S—, —N— and —CO—,
• R3 represents one of an alkyl group and a cycloalkyl group each of which has 1 to 16 carbon atoms and may have at least one substituent and an aryl group may have at least one substituent and
• R4 and R5 each independently represents one of an alkyl group, cycloalkyl group and aryl group each of which may have at least one substituent.