| Amorphous silicon nitride films were deposited under systematically varied process conditions in a PECVD reactor. All of the films were found to contain nominally 20 atomic percent total hydrogen, but the Si-H/N-H bond concentration ratio varied over a range from 0.4 to 8. Thermal stability of the films was evaluated by ramp annealing from room temperature to 500{dollar}spcirc{dollar}C. Films with the lowest concentrations of Si-H were found to undergo the least stress change upon annealing. None of the films exhibited any experimentally significant change in the as-deposited bond absorption peaks after annealing. However, all of the films developed an additional peak at {dollar}sim{dollar}630 cm{dollar}sp{lcub}-1{rcub}{dollar}. Two distinct hydrogen outgassing peaks were observed, but the absolute amount of desorbed hydrogen was very small. The presence of "loosely bound" hydrogen is suggested to explain these phenomena. When vacuum annealed to 1000{dollar}spcirc{dollar}C, each of the films exhibited either blistering, crystallization, or no apparent change. |
