Isotropic atomic layer etch for silicon oxides using no activation
AssigneeLam Research Corporation
InventorsIvan L. Berry, III, Pilyeon Park, Faisal Yaqoob
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Abstract
Methods for controlled isotropic etching of layers of silicon oxide and germanium oxide with atomic scale fidelity are provided. The methods make use of NO activation of an oxide surface. Once activated, a fluorine-containing gas or vapor etches the activated surface. Etching is self-limiting as once the activated surface is removed, etching stops since the fluorine species does not spontaneously react with the un-activated oxide surface. These methods may be used in interconnect pre-clean applications, gate dielectric processing, manufacturing of memory devices, or any other applications where accurate removal of one or multiple atomic layers of material is desired.
Claims18
A method of controllably etching a semiconductor oxide layer on a substrate, the method comprising:
- (a) contacting the substrate housed in a process chamber with excess NO species to modify the surface of silicon or germanium oxide on the substrate by adsorption, forming Si/Ge—O—N—O bonds, such that the oxide on the substrate surface is saturated with NO bonding, preventing etching from occurring;
- (b) contacting the substrate with an F etchant after the surface of the modified oxide is saturated with Si/Ge—O—N—O bonds;
- (c) desorbing nitrogen oxide from the surface of the modified oxide, while leaving a surface activated towards etching;
- (d) allowing the F etchant to etch the activated surface.
Dependencies are inferred from the claim text.