ELECTRON AND HOLE TRAPPING IN DOPED OXIDES

An electron paramagnetic resonance, thermally stimulated current, and capacitance-voltage study has been carried out on phosphorus (PSG), bo ron (BSG), and boron and phosphorus (BPSG) co-doped oxide films on Si. The principal spin-active defects are the phosphorus-oxygen-hole-cent er (POHC) and the boron-oxygen-hole-center (BOHC), which are unpaired electrons on oxygen atoms with P or B in the near vicinity. The center s are activated by hole capture. We find that holes are trapped in the PSG, BSG, and BPSG dielectrics; however, hole trapping is most effect ive in the PSG and BPSG dielectrics. We find that electrons are trappe d to differing extents in the doped films. The BPSG films are the most efficient in trapping electrons the PSG films are the least efficient . The electrical data can be explained by assuming that the precursor to the BOHC is negatively charged and the precursor to the POHC is ele ctrically neutral. Last, the charge trapping properties of PSG, BSG, a nd BPSG dielectrics are compared and contrasted with those observed in thermally grown oxides.