Standard substrate wafers and substrate wafers having a thin polycrystalline silicon layer deposited on the backside were heavily doped with antimony at the concentration of 4×1018 atoms/cm3, and then annealed at temperatures ranging between 500 and 950 °C prior to epitaxial deposition. As‐deposited wafers were annealed at 1050 °C in dry oxygen ambient for 16 h. Enhanced precipitation of oxygen in epitaxial wafers having polysilicon backside substrate was observed when preannealing was performed in the temperature range above 750 °C. This was found to be directly related to the thermal process used in polysilicon deposition. An improvement in minority‐carrier generation lifetime was noticed in the preannealed epitaxial wafers. In comparison to standard epitaxial wafers, little or no improvement in the gettering effectiveness in epitaxial wafers having polysilicon backside substrate was observed. The reason can be due to the formation of microtwins, and recrystallization of the polycrystalline silicon grains occurred during epitaxial deposition. This can lead to stress relaxation in the polysilicon backside layer and degradation of gettering effectiveness.