Aluminum-copper alloy evaporated films with low via resistance

Claim 1

A method of fabricating thin film interconnected metallization on a dielectric coated integrated circuit substrate having ohmic contact via openings through said dielectric to elements of said circuit, comprising: forming a vacuum environment about said substrate; heating said substrate in said vacuum environment to between about 180° C. to about 200° C. to condition said substrate for deposition of first level metallization film; discontinuing said heating and coincidently initiating evaporation of said first level metallization to deposit, during cooling of said substrate, a first aluminum-copper metal film over said dielectric and in said ohmic contact via openings; defining in said first metallization film a predetermined interconnection pattern to said circuit elements; depositing a dielectric layer over said first metallization level and said dielectric coating; forming a second pattern of via openings in said dielectric layer to expose selected portions of said first metallization pattern; dry etching to sputter clean said exposed first level metallization pattern and said dielectric layer in an inert atmosphere and at ambient temperatures; initiating evaporation of a second level aluminum-copper film at ambient temperatures over said dielectric layer and in said second vias and coincidentally initiating heating of said substrate to a temperature in the range of about 150° C. to about 200° C. over the deposition time of said evaporation of said second level metallization.

Claim 2

A method of fabricating thin film interconnected metallization on a dielectric coated integrated circuit substrate having ohmic contact via openings through said dielectric to elements of said circuit, comprising: forming a vacuum environment about said substrate; heating said substrate in said vacuum environment to between about 180° C. to about 200° C. to condition said substrate for deposition of first level metallization film; discontinuing said heating and coincidently initiating evaporation of said first level metallization to deposit, during cooling of said substrate, a first aluminum-copper metal film over said dielectric and in said ohmic contact via openings; defining in said first metallization film a predetermined interconnection pattern to said circuit elements; depositing a dielectric layer over said first metallization level and said dielectric coating; forming a second pattern of via openings in said dielectric layer to expose selected portions of said first metallization pattern; dry etching to sputter clean said exposed first level metallization pattern and said dielectric layer in an inert atmosphere and at ambient temperatures; initiating evaporation of a second level aluminum-copper film at ambient temperatures over said dielectric layer and in said second vias and coincidentally initiating heating of said substrate to a temperature in the range of about 150° C. to about 200° C. over the deposition time of said evaporation of said second level metallization.