Method for Laterally Trimming a Hardmask

摘要

Techniques herein include methods for controllable lateral etching of dielectrics in polymerizing fluorocarbon plasmas. Methods can include dielectric stack etching that uses a mask trimming step as part of a silicon etching process. Using a fluorocarbon mixture for dielectric mask trimming provides several advantages, such as being straightforward to apply and providing additional flexibility to the process flow. Thus, techniques herein provide a method to correct or tune CDs on a hardmask. In general, this technique can include using a fluorine-based and a fluorocarbon-based, or fluorohydrocarbon-based, chemistry for creating a plasma, and controlling a ratio of the two chemistries. Without the hardmask trim method disclosed herein, if a hardmask CD is not on target, then a wafer is scrapped. With hard-mask trim capability in silicon etch as disclosed herein, a given CD can be re-targeted to eliminate wafer-scraps.

主权项

1. A method for etching features on a substrate, the method comprising:
disposing a substrate on a substrate holder in a plasma processing system, the substrate having a patterned hardmask defining openings that expose an underlying substrate, the patterned hardmask having features with a critical dimension (CD) greater than a predetermined specified critical dimension of target features; flowing an etching process gas into the plasma processing system, the etching process gas comprising a fluorine-containing gas; flowing a passivating process gas into the plasma processing system, the passivating process gas comprising a fluorocarbon; forming plasma from the etching process gas and the passivating process gas such that the substrate is exposed to the plasma; and laterally etching sidewalls of the hardmask using products of the plasma by controlling a ratio of etching process gas to passivating process gas, and by controlling electrode bias in the plasma processing system.