The quantitative determination of the residual stress profile in oxidized p⁺ silicon films

This paper presents a quantitative method to determine the profile of the residual stress through the depth of a highly boron-doped silicon film. First, the stress profile relative to the stress at the neutral surface of the film is determined by least-square estimation using the measured vertical deflection of p⁺ silicon cantilevers with different etch depths. Secondly, the average of the residual stress is obtained from the measured deflection of a rotating beam structure. The stress profile is determined completely from these two determinations. Two examples for the application of this method illustrate that most of the p⁺ region is subjected to the tensile stress except the region near the front surface and that the stress gradient of the film oxidized at 1100 °C is steeper than that of the film oxidized at 1000 °C.