UNIFORM, DAMAGE FREE NITRIDE ETCH

摘要

An integrated circuit may be formed by forming a sacrificial silicon nitride feature. At least a portion of the sacrificial silicon nitride feature may be removed by placing the integrated circuit in a two-step oxidized layer etch tool and removing a surface layer of oxidized silicon from the sacrificial silicon nitride feature using a two-step etch process. The two-step etch process exposes the integrated circuits to reactants from a plasma source at a temperature less than 40° C. and subsequently heating the integrated circuit to 80° C. to 120° C. while in the two-step oxidized layer etch tool. While the integrated circuit is in the two-step oxidized layer etch tool, without exposing the integrated circuit to an ambient containing more than 1 torr of oxygen, at least a portion of the sacrificial silicon nitride feature is removed using fluorine-containing etch reagents, substantially free of ammonia.

主权项

1. A method of forming an integrated circuit, comprising the steps:
forming a sacrificial silicon nitride feature on said integrated circuit; forming a surface layer of oxidized silicon on an exposed surface of said sacrificial silicon nitride feature; placing said integrated circuit in a two-step oxidized layer etch tool, so that a substrate of said integrated circuit is on a substrate base of said two-step oxidized layer etch tool, said substrate base being at a temperature less than 40° C.; generating a plasma in said two-step oxidized layer etch tool using a fluorine-containing gas, ammonia and an inter gas so as to produce fluorine radicals which adsorb onto said surface layer of oxidized silicon and react with said surface layer of oxidized silicon while said substrate is on said substrate base; raising said substrate off said substrate base proximate to a heated element of said two-step oxidized layer etch tool so that by-products of a reaction between said fluorine radicals and said surface layer of oxidized silicon are removed, said heated element being at a temperature above 90° C.; subsequently lowering said substrate onto said substrate base; and generating a plasma in said two-step oxidized layer etch tool using fluorine-containing reagents which are substantially free of ammonia so as to produce fluorine radicals which react with silicon in said sacrificial silicon nitride feature so as to remove at least a portion of said sacrificial silicon nitride feature, so that said integrated circuit is not exposed to an ambient containing more than 1 torr of oxygen between said step of raising said substrate off said substrate base and the instant step.