Analysis of laser CVD SiN-Si system TFD characteristics by DLTS

SiN-Si TFD (thin film diode) was fabricated by photo-chemically depositing SiN films on Si substrate by ArF excimer laser CVD and depositing Al electrodes on SiN films by evaporation. SiN films were deposited from SiH₄ (95% SiH₄+5% Ar), NH₃ (99.99%) gas mixture with N₂ carrier gas. The substrate temperatures and chamber pressures were varied to investigate the properties of SiN film and their effects on TFD characteristics. And the optimum condition for SiN deposition was achieved. Deposition rate and refractive index of SiN film showed a strong dependence on substrate temperature. This result is in accordance with the FT-IR analysis which apparently showed the dependence of N-H, Si-H and Si-N bonding strength on substrate temperature. High frequency C-V curve showed slight hysteresis and interface state density N_ss obtained from DLTS signals with different DLTS timings (T_D, T_P, T_S) decreased with increasing substrate temperature and a increased slightly with increasing chamber pressure