Patent ID: 8716137

Claim:
A method for etching polycrystalline silicon, comprising: holding the polycrystalline silicon at a temperature higher than or equal to T E (K) given in a following equation; and etching the polycrystalline silicon by dry etching with an etching gas containing CF 4 and O 2 , T E = - 0.114 ⁢ x + 0.0556 k × ln ⁢ { ( 1 - r / d ) × - 6.27 ⁢ x + 5.38 - 2.01 ⁢ x + 3.11 } where d (nm) is etching amount of the polycrystalline silicon, r (nm) is surface roughness of the polycrystalline silicon after the etching, x is ratio of flow rate of CF 4 gas to sum of flow rate of the CF 4 gas and flow rate of O 2 gas, and k (eV/K) is Boltzmann constant.