Preservation of Integrity of Protective Coatings During Anneal in Oxygen-Free Ambients
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
Thermal drive-in cycles in oxygen-free ambients are used, for example, in CMOS (complementary metal-oxide semiconductor) processes which may lead to failure of protective oxide coatings. The failure causes altered distribution of dopants in adjacent Si areas, which increases contact resistance, reduces speed, and influences long term degradation of shallow devices. The addition of oxygen in ppm concentration to the anneal ambient prevents oxide failure. CMOS processes require high active dopant densities at source/drain contacts for good contact resistance and controlled doping profiles to optimize device performance. Yield, contact resistivity and speed are problems of currently employed CMOS processes.