Method to reduce contact resistance by means of in-situ icp

Abstract

A process is described for etching contact holes though a dielectric layer down to a silicon surface. Initial etching, until the silicon is exposed, is performed in a suitable plasma environment under high RF power. This results in damage to the newly exposed silicon surface. Said damage is repaired by exposing the silicon and the photoresist to an atmosphere that includes carbon tetrafluoride and atomic oxygen. The latter oxidizes the damaged layer, allowing it to be removed by the former. Much of the photoresist is also removed by the atomic oxygen, any that still remains being then removed using a wet etch. At the user's option, the silicon may be allowed to overetch during the high RF power application and/or a low power RF step may be introduced to partially remove silicon surface damage prior to the atomic oxygen treatment.