The effects of ion implantation, interstitial oxygen concentration, and heat treatment after ion implantation on the formation of stacking faults induced by boron ion implantation were investigated. The stacking faults were formed during oxidation when interstitial oxygen coexisted with boron atoms, and the density of the stacking faults increased with oxygen concentration. From these results, it is found that boron atoms promote the formation of oxygen precipitates which act as nuclei for stacking faults. In addition, the effect of the stacking faults induced by boron ion implantation on gate oxide lifetime distribution was investigated. The gate oxide lifetime distribution was found to improve by depressing the stacking faults.