The effects of oxidation temperature on the capacitance-voltage characteristics of oxidized AlN films on Si

The thermal oxidation of AlN thin films products a high quality insulator which exhibits the gate voltage-controlled charge regimes of accumulation, depletion, and inversion on Si surfaces. The temperature dependence of oxidation is important for device processing, We report on the composition. structure, and electrical properties of the AlN versus the oxidization temperature. AIN layers 500 nm thick were deposited by rf sputtering on p-type Si (100) substrates, followed by oxidation in a furnace at temperatures from 800 to 1100 degrees C with O-2 flow. An oxidation time of 1 h produced layers of Al2O3 with small amounts of N having a thickness of 33 nm at 800 degrees C, and 524 nm at 1000 degrees C. Electrical measurements of metal-oxide-semiconductor capacitors indicated that the dielectric constant of the oxidized AlN was near 12. The best layer had a flatband voltage near zero with a net oxide trapped charge density less than 10(11) cm(-2). These results show that oxidized AlN has device-grade characteristics for the gate regions of held effect transistors, and for optoelectronic applications. (C) 1997 American Institute of Physics. [S0003-6951(97)04652-4].