Relationship between electron sensitivity and chemical structures of polymers as EB resists: Poly(lactam thioether) as new positive EB resists

Poly(lactam thioether) was synthesized from tetrahydro‐1,4‐thiazepine‐5(4H)‐one by a ring opening reaction under various conditions and was evaluated as positive electron beam(EB) resist. It was found that poly(lactam thioether) was easily decomposed by EB irradiation. The decomposition by EB exposure may be attributed to cleavage of CS bonds in the polymer chains. The sensitivity of poly(lactam thioether) was influenced by prebake temperature, molecular weight, and developer, a high sensitivity of 5.3 × 10 −6 coulomb/cm 2 was observed with a good resolution of less than 1 μm. Poly(lactam thioether) showed a high sensitivity and a high resolution, and is suitable as a positive EB resist.