Analysis of Si-H frequency shift in plasma-deposited SiN.

Plasma SiN has been deposited at low NH3/SiH4 gas flows in a Pacific Western Systems Coyote reactor at AT&T-TS-RD. The N/Si ratio in the film is proportional to the NH3/SiH4 gas flow in the reactor. The Si-H peak in the infrared spectrum of the SiN shifts to lower frequency as the N/Si of the film decreases. We use the random-bonding model to calculate the average electronegativity that a Si-H bond experiences for a particular N/Si ratio in the film. The Si-H frequency correlates with the calculated electronegativities and agrees with a correlation of Si-H frequency and electronegativity obtained for molecules.