Bridge type structure photoresist resin, KrF photoresist composition and preparation method thereof

The invention belongs to the technical field of photoresists, and particularly relates to a bridge-type structure photoresist resin, a KrF photoresist composition and a preparation method of the bridge-type structure photoresist resin and the KrF photoresist composition. The preparation method of the bridge type structure photoresist resin comprises the following steps: S1, a first monomer, a second monomer, a third monomer and a fourth monomer are subjected to a polymerization reaction in the presence of an initiator to obtain a copolymerization product, the first monomer is 4-acetoxystyrene, the second monomer has a structure represented by a formula (1), and the third monomer has a structure represented by a formula (2); the third monomer has a structure as shown in a formula (2), and the fourth monomer has a structure as shown in a formula (3); and S2, carrying out hydrolysis reaction on the copolymerization product obtained in the step S1 in the presence of a catalyst to obtain a product containing the b