DEPOSITION OF MOBILE-ION FREE ALUMINUM AND ALUMINUM ALLOY FILMS FOR HIGH STABILITY MOS GATE STRUCTURES

摘要

Gate voltage instabilities in MOS devices have been attributed primar¬ily to mobile ion impurities in the SiO2 dielectric. These impurities are shown not to originate during thermal gate oxidation, but during subsequent contamination at the onset of evaporation for gate metallization. This paper describes the use of rf induction-heated crucible evaporation in conjunction with a new and practical approach for deposition of either aluminum or alum¬inum alloys for high purity gate-metallization, yielding devices which consistently exhibit mobile ion densities of 5 x 109/cm2 or less.nThe additional use and adaptability of this technique for single source deposition of alloys of silicon and aluminum for device metallization is also discussed.