Study Of Nitrogen And Its Related Complexes In The Nitrogen-implanted Silicon

Nitrogen has a heavy impact on the properties of the single crystal silicon, and its properties, forms and mechanisms on reactions with related defects have been intensively investigated. In this thesis, nitrogen was implanted into the silicon wafers, which were subsequently annealed by rapid thermal processing (RTP) and then characterized by Fourier transform infrared spectroscopy (FTIR), spreading resistance profiles (SRP) as well as doppler broadening spectroscopy (DBS), The nitrogen - vacancy complexes, the nitrogen - oxygen complexes, and the effect of nitrogen on the electrical properties of the silicon wafers has been studied. Briefly, the main contents and achievements in the work are as follows:1. After analyzing the FTIR results of the nitrogen implanted silicon wafers (CZ-Si and FZ-Si) processed by RTP at different temperatures, it was found that four novel infrared absorption peaks appeared when the wafers were processed in the 750 °C 850 °C temperature range. And the mechanism for the annealing behaviors of those infrared absorption peaks was discussed. Furthermore, a new model for the complexes was proposed based on the predecessors' theoretical results, and it was further confirmed by the computer simulations that the new peaks were related with the N₂V₂ complexes.2. The electrical properties of the nitrogen-implanted silicon wafers processed by RTP at different temperatures were characterized by SRP, and it was found that as the RTP temperature increased, the near surface spreading resistances of the n type nitrogen-implanted silicon wafers decreased, i.e., the concentration of the carriers increased. As the substitutive nitrogen in silicon acts as donor, it is strongly believed that some interstitial nitrogen atoms were changed to be substitutive ones and then the concentration of the carriers was increased.3. The variation of the vacancy concentrations in the nitrogen-implanted silicon wafers with RTP treatments at different temperatures was characterized by DBS. It was found that S, indicating the variation of the vacancy concentrations, decreasedas the RTP annealing temperature increased, which meant the vacancy concentrations in the nitrogen-implanted silicon wafers decreased as the RTP annealing temperature increased. And the vacancy concentration was the lowest when the RTP annealing temperature was 850 °C. With the analyses from the FTIR results, it is believed that the vacancies interacted with the nitrogen atoms to form complexes as the RTP annealing temperature increases.4. The evolution of the nitrogen - oxygen complexes in the n type FZ-Si with the co-implantation of nitrogen and oxygen was investigated and characterized by FTIR after RTP treatments at different temperatures. It was found that in the temperature range of 0 850 °C, the intensities of the infrared absorption peaks of the nitrogen - oxygen complexes increased first and then decreased as the RTP annealing temperature increased. In the temperature range of 450 650 °C, the intensities increased, and the intensities became the strongest when the annealing temperature was 650 °C. And the nitrogen - oxygen complexes disappeared when the RTP annealing temperature reached 750 °C. However, the intensities of the nitrogen pair related infrared absorption peaks increased in the temperature range of 650- 750 °C, which was attributed to the dissociation of the nitrogen - oxygen complexes into interstitial nitrogen atoms and oxygen atoms.5. The variation of the electrical properties of the n type FZ-Si wafers with the co-implantation of nitrogen and oxygen was characterized by SRP after the RTP treatments in the temperature range of 650 950 °C. It was found that the concentration of the carriers in the near surface of the silicon wafers increased as the RTP annealing temperature increased. From the FTIR results, it is believed that some implanted nitrogen atoms out-diffused to the near surfaces of the silicon wafers and some of the out-diffused atoms then transformed into substitutive nitrogen atoms, which further increased the concentration of the donors and then increased the concentration of the carriers, though the electrical active nitrogen -oxygen complexes were dissolved after the above RTP treatments.