A ball-indentation method to evaluate the critical stress for dislocation generation in a silicon substrate

Although silicon substrates for semiconductor devices do not contain any dislocations initially, the thin-film stresses sometimes produce dislocations during fabricating processes. Since the dislocations degrade electrical characteristics, it is important to estimate the critical stress for dislocation generation in order to maintain the integrity and reliability of the device. Therefore, we have developed a method that uses a ball-press test for evaluating the critical stress for dislocation generation. The critical stress is calculated from the critical press load for dislocation generation. We used this test method to determine the temperature dependence of the critical stress, and found that the change of the critical stress with temperature is not so large when compared with that of the reference tensile test data. This is because, since the tensile specimen contains some dislocations or initial damage, the tensile test data probably includes the influence of the movement of these dislocations. Furthermore, the effect of ion implantation was examined and this makes clear that the critical stress of implanted specimen is decreased.