Nickel silicide as a contact material for submicron CMOS devices

Abstract

Nickel monosilicide (NiSi) is an attractive alternative to the currently used silicides for the coming generations of deep submicron complementary metaloxide-semiconductor (CMOS) devices. This silicide material has a resistivity, which is comparable to that of TiSi2 or CoSi2, but consumes less silicon for its formation. The silicide silicon interface is relatively planar and, unlike TiSi2, its resistivity does not change with the linewidth for narrow lines. However, the thermal stability of NiSi is relatively poor at the currently used temperatures during process integration. Recent studies have shown that the stability of these films could be increased substantially through the small addition of alloy elements, which do not increase the resistivity of the NiSi film. Morever, it has been demonstrated that the addition of a small amount of alloy elements significantly reduces diode leakage, possibly due to the suppression of silicide spike formation as a result of alloy addition. This paper will present and discuss the details of these experimental results.