Characteristics of aluminum-titanium electrical contacts on silicon

Abstract

An aluminum‐titanium metallization scheme for use in silicon integrated circuits is described. This metallization can produce high‐conductance electrical contacts with negligible dissolutions of silicon. The desirable contact is lost, however, if a TiAl₃ reaction product is allowed to consume the entire Ti layer. The TiAl₃ forms during the postmetallization heat treatment used to stabilize the electrical characteristics of the contact. The Ti layer is found to be consumed in this reaction at a rate proportional to t^1/2, where the rate constant is determined to be d=d₀ exp(−E_a/kT), where d₀ ≈ 0.15 cm²/sec and E_a ≈ 1.85 eV. This rate constant can be used to determine the thickness of titanium layer necessary to produce the desirable electrical contact.