Methods for achieving width control in etching processes

摘要

A method includes performing a patterning step on a layer using a process gas. When the patterning step is performed, a signal strength is monitored, wherein the signal strength is from an emission spectrum of a compound generated from the patterning step. The compound includes an element in the patterned layer. At a time the signal strength is reduced to a pre-determined threshold value, the patterning step is stopped.

主权项

1. A method comprising:
performing a patterning step on a first layer using a process gas, wherein the patterning step comprises:
an etching step for etching down the first layer; andafter the first layer is etched through, performing a trimming step on the first layer to remove parts of the first layer; 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.