Segregation of gallium at SiO2/Si interfaces during sputtering with Ga+ ions: experimental and computer simulation study

The sputtering of SiO2/Si interfaces with gallium ions was studied both experimentally by using secondary neutral mass spectrometry (SNMS) and by computer simulations by means of a dynamic Monte Carlo code. Oscillations of the gallium signal (from implanted primary ions) at the interface between the SiO2 and Si layers were observed. By means of computer simulations, it was shown that cascade effects alone cannot explain the experimental depth profiles. A model that includes additional defect transport phenomena such as bombardment-induced segregation is proposed and incorporated in an existing dynamic Monte Carlo computer code. The simulations with the new code give rise to profiles that are comparable with the experimental ones, confirming the correctness of the chosen approach.