Patent ID: 8187980

Claim:
An etching method for forming a groove by etching a silicon layer of a substrate by using a mask which has a first region where an opening with a first opening width is formed and a second region where an opening with a second opening width larger than the first opening width is formed, the method comprising: mounting the substrate on a mounting table in a processing chamber; converting a processing gas containing Cl 2 gas, HBr gas, and one of CO gas and CO 2 gas into a plasma; and etching the silicon layer by the plasma to thereby make substantially identical sidewall tilt angles of protruded portions between grooves in a first and a second etched region respectively corresponding to the first and the second region of the mask, wherein a flow rate of one of the CO gas and the CO 2 gas is controlled such that an added amount of micro-loading indicated as a ratio of a groove depth in the second etched region to that in the first etched region is about 10% or less compared with a case of using neither the CO gas nor the CO 2 gas, and wherein the mask is patterned such that a ratio of the second opening width to the first opening width is about 6 or more.