US 5,962,345 A · 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.

Claims18

Dependent claims

An etching method for contacting a silicon body through a dielectric layer, comprising the sequential steps of:

(a) forming a photoresist pattern on said dielectric layer;
(b) at an RF power level, plasma etching the dielectric layer, wherever it is not covered by the photoresist, until a surface of the silicon body is uncovered;
(c) exposing said uncovered silicon surface to an atmosphere that includes carbon tetrafluoride and unionized atomic oxygen, obtained from an ICP oxygen source from which all ions and emitted ultraviolet light have been removed, thereby removing photoresist and plasma induced damage of the uncovered silicon surface;
and
(d) then removing any remaining photoresist by means of a wet etch.

2 more elements

Dependencies are inferred from the claim text.

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

Life of this patent

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

Life of this patent

Abstract

Claims18