Stress effect on the kinetics of silicon thermal oxidation

Abstract

Oxidation of silicon wafers under external mechanical stress was studied in this work. From the oxide thickness profile measured by an automatic-scanning ellipsometer, it was found that the oxidation kinetics of silicon were significantly affected by mechanical stress. There are two distinct features of oxide thickness distribution corresponding to short and long times. By comparing the kinetic constants taken from experiments and the simulated stress distribution on the silicon wafer, we can possibly explain the two features of oxide thickness distribution: the initial rate constant is deformation dependent and the parabolic rate constant is stress dependent. The observed stress-dependent oxidation rates are important in the study of thin gate oxide reliability.

Coupled mechanical-oxidation modeling during silicon thermal oxidation process

“…5(a). The predicted curve agrees well with the experimental data provided by Tamura et al 31 Moreover, experimental results by Hwu et al 33,34 and Kao et al 7,29 also indicated that tensile loads accelerated the silicon oxidation process while compressive load retarded it. However, since the aim of their experiments was to investigate the non-uniform oxidation behavior of two-dimensional silicon specimens, it is hard to compare their results and the present prediction results directly.…”

“…Combining Eqs. (16), (34) and (35), when the elastic strain of substrate is much smaller than 1, the creep stain of the substrate can be expressed as…”

“…31,32 In the third category, the effect of external loads on the oxidation behavior of silicon was considered. Yen et al 33,34 placed two silicon wafers vertically at one side and put a small slice of quartz across the middle of the wafers to make them bend. However, although the bending deformation of the samples remained constant, the bending moment would diminish with time due to creep deformation.…”

Creep of Hi-Nicalon S Ceramic Fiber Tows at 800 deg C in Air and in Silicic Acid-Saturated Steam

“…In cases of stressed oxidation, as with SiC fiber tows used to reinforce CMCs, the oxidation rate is significantly affected by the presence of the stress. For tensile stresses, the rate increases [125,199,200], whereas compressive stresses tend to decrease the rate. This is due, in part, to the effect of stress on crack growth.…”

“…Yen and Hwu [199,200] found that tensile stress strongly enhances the oxidation rate of silicon and that the parabolic rate constant was stress dependent. Hay noted that SiC oxidation is very similar to that of silicon [142].…”