Influence of segregation annealing time on the gettering process

The influence of segregation annealing time on the gettering efficiency of phosphorous ion implantation gettering in MOS structures was investigated. The gettering was performed by a backside P ion implantation with a dose of 10(16) atoms/cm(2) and 120 KeV energy. To investigate the gettering effici ency, surface generation velocity and 3-dimensional generation lifetime pro file as a function of the annealing time were investigated. It was found th at there is an optimum annealing time for maximum gettering efficiency. Sur face generation velocity and generation lifetime increase for annealing les s or equal to the optimum annealing time, which was 90 min for our case. Fo r longer annealing times both parameters deteriorate. The analysis of the r esults shows that the increase of generation lifetime and the decrease of s urface generation velocity are due to a gettering of metallic impurities an d shrinkage of oxidation stacking faults (OSFs). The deterioration of these parameters for annealing times longer than the optimum annealing time is e xplained by the combined influence of OSFs shrinkage, release of the captur ed metallic impurities from gettering sites in the damaged implanted region and by metallic impurities contamination from the furnace. The concept of the optimum annealing time is incorporated in the segregation model of the gettering process.