ANNEALING CHARACTERISTICS OF ULTRATHIN SILICON-OXIDES GROWN AT LOW-TEMPERATURES

Optical, mechanical, and electrical properties of ultrathin gate oxide grown at temperatures ≤700°C in dry O2 have been studied as a function of annealing temperature in the range of 700°C to 1000°C. The effective refractive index of these films was found to decrease with increasing anneal temperature. Strong reduction in intrinsic film stress was observed at anneal temperatures over 900°C. Fixed charge densities, threshold voltages, and breakdown field strength are correlated with anneal temperatures. Fully processed poly-Si gate MOS devices indicate that oxides grown at 700°C and annealed at 900°C are suitable for device applications, while maintaining the benefit of low thermal budget. Conventional in situ post-oxidation anneal above 1000°C is not required, as all post-gate thermal cycles provide adequate annealing. © 1990, The Electrochemical Society, Inc. All rights reserved.