Patent ID: 9040317
Filing Date: 2015-05-26
Classification: H01L

Abstract:
1. A method comprising: performing a patterning step on a first layer using a process gas, wherein the patterning step comprises: when the patterning step is performed, monitoring a signal strength from an emission spectrum of a compound generated from the patterning step, wherein the compound comprises a first element in the first layer, and wherein the signal strength is monitored during the trimming step; monitoring an additional emission spectrum of an element in a second layer underlying the first layer, wherein the first layer and the second layer are formed of different materials; at a time after the additional emission spectrum indicates a presence of the element in the second layer, recording a value of the signal strength; determining a threshold value based on the recorded value of the signal strength; and stopping the patterning step once the signal strength is reduced to the threshold value.