Process for corrosion free multi-layer metal conductors.

摘要

A thin-layer metallization structure in which the final gold layer is deposited by evaporation with the surface onto which it is evaporated maintained at an elevated temperature. The thin-film metallization pad structure is deposited onto a substrate (12), typically made of a ceramic or glass-ceramic the assembly mask through opening (23) of a metal mask (24). The assembly mask substrate is placed in an appropriate evaporation system which is pumped down to about 0,13 10 <-><3>Pa and heated to about 200 DEG C for 15 to 30 minutes in order to outgas the assembly. In turn, the substrate is heated to 150 DEG centigrade and an adhesion layer such as 20 nm layer (11) of chromium is deposited. Next, a cushion layer (13), such as copper, and a diffusion barrier layer (15), such as titanium, are deposited sequentially still by evaporation as the subtrate cools from the initial temperature of 150 DEG C to about 100 DEG C. The copper layer (13) is about 6 microns thick and the titanium layer (15) is about 1 micron thick. Now, the substrate is reheated to 200 DEG C and a gold layer (17') of about 1 micron thick is deposited by evaporation onto the structure. The heat is then turned off and the assembly allowed to cool to 50 DEG C or less. The gold layer (17)' encapsulates the underlying multi-layer structure to prevent oxidation and diffusion of copper and in turn, prevent corrosion. By evaporating the gold layer at an elevated substrate temperature, the gold atoms have a higher mobility, so that the gold is spread over the edges of the structure for perfect coverage thereof.