Patent ID: 7141510

Claim:
A plasma processing method, comprising the steps of: supplying a processing gas into an airtight processing chamber, plasmizing the processing gas, and plasma-processing a target layer formed on an object to be processed by using a resist film as a mask, wherein the plasma-processing is conducted while a process condition is being changed on the basis of a variation of a thickness reduction rate of the resist film, wherein the plasma-processing step includes: a first process of plasma-processing the target layer while the thickness of the resist film is being monitored until the thickness reduction rate of the resist film reaches a predetermined value; and a second process of plasma-processing the target layer under a changed process condition in which selectivity against the resist film is higher than in the first process, and wherein the second process is conducted by using a processing gas containing a gas species which is identical to a by-product gas species produced during first process to reduce the thickness reduction rate of the resist film, an amount of the by-product gas species being reduced as the first process proceeds.