High selectivity SiC etch in integrated circuit fabrication

Details High selectivity SiC etch in integrated circuit fabrication High selectivity SiC etch in integrated circuit fabrication

2001-08-13

2004-06-01

Norton, Nadine G. (Department: 1765)

Semiconductor device manufacturing: process

Chemical etching

Combined with coating step

C438S706000, C438S712000, C252S079400

Reexamination Certificate

active

06743725

ABSTRACT:

FIELD
The subject matter herein relates to fabrication of integrated circuits using a silicon carbide (SiC) etch stop layer.
BACKGROUND
In the fabrication of integrated circuits in and on a silicon wafer, particularly with copper (Cu) Damascene metallization processes, a silicon carbide (SiC) film, or layer, is commonly used as an etch stop, barrier or hard mask during plasma etching processes. The SiC film is relatively nonreactive to the plasma etch, which is typically used to remove silicon oxide, organo-silica-glass or other low k (dielectric constant) type materials that may be used in combination with the Cu Damascene metallization processes. Thus, the SiC film enables the plasma etch of the low k type material to stop at a desired depth or protects the underlying material from the plasma etch.
When it is necessary to remove the SiC film, an etch process is used that is relatively “selective” to the SiC. The SiC etch process typically uses CF4 (Carbon-Tetrafluorite), CHF3 (Trifluoromethane), CH2F2 (Difluoro-Methane ), CH4 (Methane) or the like as an etch chemistry. It is very difficult, however, to achieve a high selectivity to the SiC film that does not also affect the low k type material, thereby causing damage to, or erosion of, the low k type material.
It is with respect to these and other background considerations that the subject matter herein has evolved.
SUMMARY
The subject matter herein involves a new and improved etch chemistry for an improved SiC etch process that enhances, or increases, the selectivity of the etch process to the SiC film relative to the silicon oxide, OSG or other low k type material. In one particular embodiment, hydrogen (H2) or other hydrogen-containing gas is added to the prior art etch chemistry. Hydrogen has been found to facilitate the etching of the SiC film, while reducing the etch rate of the low k type material. In another particular embodiment, ammonia (NH3) is added to the prior art etch chemistry also to facilitate the etching of the SiC film and reduce the etch rate of the low k type material. In either embodiment, the selectivity of the etch chemistry to the SiC film is increased as compared to that for the low k type material. Thus, the SiC film can be more easily removed without damaging or eroding the low k type material.
A more complete appreciation of the present disclosure and its scope, and the manner in which it achieves the above noted improvements, can be obtained by reference to the following detailed description of presently preferred embodiments taken in connection with the accompanying drawings, which are briefly summarized below, and the appended claims.


REFERENCES:
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patent: 6251770 (2001-06-01), Uglow et al.
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patent: 6358842 (2002-03-01), Zhou et al.
patent: 6368979 (2002-04-01), Wang et al.

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