Stresses generated by the thermomigration of liquid inclusions in silicon

Estimates of the stresses generated in a silicon wafer by thermomigration processing indicate the potential presence of stresses ranging from 1.7×10−1 to 7×103 MPa. The causes of these stresses include the heating and cooling of the wafer, the partial infrared transparency of silicon, thermal edge losses from the periphery of the wafer, the increasing solubility of silicon in the inclusion with increasing temperature, the difference in thermal conductivity between the liquid inclusion and the silicon matrix, the lattice expansion induced by impurity atoms in the dopant trials, the mismatch in thermal expansion coefficients in the Al‐Si sandwich at the completion of processing, and inclusions frozen in the wafer. Various ways of decreasing or eliminating these stresses are suggested so that the performance and yield of devices made by thermomigration will be optimized.