Deposition of thin refractory MIS structures on InP

Abstract

In the present investigation, we report on significant increases in the refractory-InP Schottky barrier by process modification of the metal-semiconductor interface. Refractory-InP MIS structures were investigated as pos-sible gate metallizations. These structures consisted of Ta/Ta₂}O₅}/InP and TiW/TiO₂} /InP. A thin layer of Ta (100å) was electron beam vapor aeposited followed by the in situ formation of Ta₂}O₅} at 300‡C and an oxygen overpressure.

The remainder of the Ta film was deposited at 90‡C substrate temperature. The TiW/TiO₂} system was formed by sputter deposition of Ti (100Aℴ), in situ oxidation to form TiO₂} followed by deposition of TiW (88 wt % W, 12 wt % Ti). Effective barrier height for the TiW/TiO /InP structure was measured to be 0.65 eV and for the Ta/Ta₂}O₂} /InP, 0.5 eV. Leakage current at-5V was less than 3 A/cm²} for both refractory-InP MIS structures. The TiW/TiO₂} /InP structure was stable up to 400-450°C, while the Ta/Ta₂ O₅/InP system degraded to 0.2 eV at 300-350‡C.