Dry-etch for silicon-and-nitrogen-containing films

Abstract

A method of etching exposed silicon-and-nitrogen-containing material on patterned heterogeneous structures is described and includes a remote plasma etch formed from a fluorine-containing precursor and an oxygen-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the exposed regions of silicon-and-nitrogen-containing material. The plasmas effluents react with the patterned heterogeneous structures to selectively remove silicon-and-nitrogen-containing material from the exposed silicon-and-nitrogen-containing material regions while very slowly removing other exposed materials. The silicon-and-nitrogen-containing material selectivity results partly from the presence of an ion suppression element positioned between the remote plasma and the substrate processing region. The ion suppression element reduces or substantially eliminates the number of ionically-charged species that reach the substrate. The methods may be used to selectively remove silicon-and-nitrogen-containing material at more than twenty times the rate of silicon oxide.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Prov. Pat. App. No. 61 / 525,067 filed Aug. 18, 2011, and titled “DRY-ETCH FOR SILICON-AND-NITROGEN-CONTAINING FILMS,” which is incorporated herein by reference for all purposes.BACKGROUND OF THE INVENTION[0002]Integrated circuits are made possible by processes which produce intricately patterned material layers on substrate surfaces. Producing patterned material on a substrate requires controlled methods for removal of exposed material. Chemical etching is used for a variety of purposes including transferring a pattern in photoresist into underlying layers, thinning layers or thinning lateral dimensions of features already present on the surface. Often it is desirable to have an etch process which etches one material faster than another helping e.g. a pattern transfer process proceed. Such an etch process is said to be selective to the first material. As a result of the diversity of materials, c...

AI Technical Summary

Benefits of technology

This patent describes a method of etching materials using plasma effluents from a remote plasma reactor. The method selectively removes silicon-and-nitrogen-containing material while preserving other exposed materials. The selectivity is achieved through the use of an ion suppression element that reduces the number of ionically-charged species that reach the substrate. The method is more than ten times faster in removing silicon-and-nitrogen-containing material compared to silicon.

Problems solved by technology

However, there are few options for selectively etching silicon nitride faster than silicon.

Remote plasma etch processes have also been developed to remove silicon nitride, however, the silicon nitride selectivity of these etch processes (relative to silicon) has been limited.

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