THERMAL RELAXATION PHENOMENA IN THE FORMATION OF DEVICE-QUALITY SIO2/SI INTERFACES

A combination of second-harmonic generation (SHG) and electrical characterization of plasma processed SiO2/Si(111) structures has enabled us to separate two different effects that contribute to interfacial electrical quality. Thermally-grown oxides, prepared at 850-degrees-C, exhibit considerable compressive strain in the bulk oxide film. In contrast, there is significantly less build-up of intrinsic strain in plasma-processed SiO2/Si Structures. As a result, the driving force for stress relaxation is much smaller compared to that of thermally-grown structures. On the other hand, interfacial relaxation, as monitored by the SHG technique, involves changes in the local bonding of Si- and 0-atoms at the SiO2/Si interface. This relaxation occurred at approximately 900-degrees-C and was sufficient to optimize the electrical properties of plasma-deposited structures.