Method for etching silicon oxide films in a reactive ion etch system to prevent gate oxide damage

摘要

The present invention discloses a method for the etching of insulating films, specifically silicon oxide films, using a fluorine- helium-oxygen gas mixture in the fabrication of semiconductor devices. The method utilizes a prior art reactive ion etch system and adds a quantity of helium to a pre-established fluorine-oxygen chemistry to reactively etch the silicon oxide film while minimizing the occurrence of gate charging resulting from damage to the gate oxide. The addition of helium gas into the etch chemistry must be such that the flow of helium is at least 20% of the sum of the total fluorine, helium, and oxygen flows. The resulting etch chemistry, which can be used in any commercially available reactive ion etch system, produces a more uniform etch while reducing gate oxide damage so as to minimize charging of the semiconductor gate.