Sputter-metallization-induced electronic defects in thermal SiO2

The generation of interface states and oxide electron traps in thermal sili con dioxide (SiO2) lavers by sputtering metallization has been investigated . The dependence of the samples on electric field and temperature during th e sputter process is observed. The interface state density spectra revealed narrow distributions indicating an increased density of band edge states. In the upper part of the Si band gap a peak was observed due to the generat ion of a particular interface defect site. Three bulk defect centers were f ound as identified by their capture cross sections of the order of 1 x 10(- 16), 3 x 10(-17) and 3 x 10(-18) cm(2). The first one is associated with ra diation induced neutral centers and is a feature of oxides metallized by sp uttering. The other two traps are believed to be related to defects like Si OH and H2O, Post metallization annealing (PMA) resulted in a reduction of t he density of the oxide and interface traps and a broadening of the interfa ce trap spectra, A speculation on the defect formation process is included.