化学気相析出法によるSi₃N₄の合成（原料ガス流量の影響）

抄録

Pyrolytic Si₃N₄ has been deposited on a graphite substrate using a SiCl₄+NH₃+H₂ system as the source material under the following conditions: SiCl₄(vapor) flow rate [FR(SiCl₄)], 100, 170 and 260 cm³/min; SiCl₄(v) to H₂ gas flow rate ratio FR(SiCl₄)/FR(H₂), about 0.26; NH₃ gas flow rate, 60 cm³/min; total gas pressure (P_tot), 10 to 80 Torr; deposition temperature (T_dep), 1100 to 1500°C. The effects of the SiCl₄(v) flow rate on the morphology, density, structure and deposition rate of Py-Si₃N₄ were investigated.
At P_tot=60 Torr, the rate of increase in layer thickness (x⁄t) became larger with FR(SiCl₄). The maximum value (1.2 mm/hr) of x⁄t for the crystalline Py-Si₃N₄ was obtained at FR(SiCl₄)=260 cm³/min, T_dep=1400°C and P_tot=60 Torr. The density of the amorphous Py-Si₃N₄ was 2.60 to 2.89 g/cm³ at FR(SiCl₄)=170 cm³/min, and 2.90 to 3.00 g/cm³ at 100 and 260 cm³/min. The observed density of the crystalline Py-Si₃N₄ was independent of the SiCl₄(v) flow rate and 3.15 to 3.18 g/cm³ (99 to 100% of a theoretical density). The structural characteristics and formation mechanism of Py-Si₃N₄ were also discussed in terms of the SiCl₄(v) flow rate.