PARAMAGNETIC DEFECT CENTERS IN BESOI AND SIMOX BURIED OXIDES

We have combined electron paramagnetic resonance and capacitance-volta ge measurements to identify the chemical nature and charge state of de fects in BESOI and SIMOX materials. The four types of defect centers o bserved, charged oxygen vacancies, delocalized hole centers, amorphous -Si centers, and oxygen-related donors, are strikingly similar. In the BESOI materials, the radiation-induced EPR centers are located at or near the bonded interface. Therefore, the bonded interface is a potent ial hole trap site and may lead to radiation-induced back-channel leak age. In SIMOX materials it is found that all of the defects in the bur ied oxide are due to excess-Si. Our results using poly-Si/thermal oxid e/Si structures Strongly suggest that it is the post-implantation, hig h temperature anneal processing step in SIMOX that leads to their exis tence. The anneal leads to the outdiffusion of oxygen from the buried oxide creating excess-Si related defects in the oxide and O-related do nors in the underlying Si substrates. Last, our study has elucidated a number of interesting aspects regarding the physical nature of a rela tively new class of defects in SiO2: delocalized spin centers. We find that they are hole traps in both SIMOX and BESOI materials.