Electron-spin-resonance study of defects in plasma-enhanced chemical vapor deposited silicon nitride

Silicon nitride films with low defect densities can be prepared by plasma-enhanced chemical vapor deposition with ammonia-to-silane ratios adjusted to obtain N-rich materials. An electron-spin-resonance signal with g value close to 2.002 is reported for such materials, and the defect is identified as a Si atom coordinated to three N atoms as observed earlier in high-temperature chemical vapor deposited silicon nitride. Densities below 1016 cm-3 are measured for substrate temperatures above 350°C for the first time. The distribution of defects is uniform through the film thickness. A surface defect density of 1012 cm-2 has also been found in films deposited at 250°C.