Patent ID: 8597769

Claim:
An etching mask comprising: a thermoplastic resin capable of etching a base material including a silicon with an etching gas including CHF 3 and/or SF 6 and the thermoplastic resin containing at least one kind of skeleton expressed by a chemical formula (1) or a chemical formula (2) in a main chain: wherein R 1 and R 2 in the chemical formula (1) are a hydrocarbon group having a carbon number of 1 to 15; and, wherein R 3 and R 4 in the chemical formula (1) are hydrogen atoms; and, wherein R 5 , R 6 , R 7 , R 8 in the chemical formula(2) are different or the same as one another, each of which is selected from the group consisting of: a hydrogen atom; a deuterium atom; a hydrocarbon group having a carbon number of 1 to 15; a halogen atom; a substituent group containing a hetero atom of oxygen or sulfur; and a ring structure formed with one another; and, wherein m and n are integers equal to or greater than 0, and the etching mask has a film thickness of 10 nm to 40 μm.