Copper germanium compounds capable of being produced at low temperature

Claim 1

A VLSI method for producing low resistance, self-aligned Cu 3 Ge, for advanced bipolar, CMOS, and BiCMOS devices comprising the steps of: providing a single crystalline semiconductor substrate (73) having at least one doped region (72) formed therein; depositing a layer (71) of SiO 2 on said substrate with at least one opening to the substrate surface at said doped region; selectively depositing a layer of Ge (78) on said exposed region on the substrate surface; depositing a Cu layer (79) on said Ge layer, whereby the Ge layer is held at room temperature; heating said layers to a temperature in the range of about 150 - 200°C to form a layer (80) of Cu 3 Ge; and removing the unreacted Cu of said Cu layer remaining after heating with a selective etch, preferably by selectively wet etching in a 10:1 solution of HNO 3 :H 2 O with selectivity of 15:1.