×

Method to improve etch selectivity during silicon nitride spacer etch

  • US 9,318,343 B2
  • Filed: 06/11/2014
  • Issued: 04/19/2016
  • Est. Priority Date: 06/11/2014
  • Status: Active Grant
First Claim
Patent Images

1. A method of etching features on a substrate, the method comprising:

  • positioning a substrate on a substrate holder in a plasma processing chamber, the substrate having a silicon nitride film covering structures on the substrate;

    flowing a first process gas mixture into the plasma processing system, the first process gas mixture comprising a halogen-containing gas;

    flowing a second process gas mixture into the plasma processing system, the second process gas mixture comprising an oxygen-containing gas;

    maintain plasma using the first process gas mixture and the second process gas mixture;

    repeatedly varying a flow rate of the first process gas mixture or repeatedly varying a flow rate of the second process gas mixture such that a gas flow ratio of the halogen-containing gas to the oxygen-containing gas fluctuates repeatedly between a first gas ratio and a second gas ratio; and

    anisotropically directing products of the plasma toward the substrate.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×