Thermal dissociation process of hydrogen atoms in plasma-enhanced chemicalvapor deposited silicon nitride films

Annealing characteristics of plasma-enhanced chemical vapor deposited silic on nitride films have been evaluated. Annealing temperature dependence for N-hydrogen bonds decreases monotonically with increasing temperature, while that for Si-hydrogen bonds initially increases and then decreases. The ann ealing time dependence of the absorption coefficients indicate the N-hydrog en bonds have two bonding configurations: one dissociates from 400 degrees C, and the other above 600 degrees C. The dissociation of the weaker config uration follows the first-order reaction, and the estimated activation ener gy is about 0.45 eV. For the Si-hydrogen bonds, the increase of the absorpt ion coefficient in the initial stage of annealing is due to the recombinati on of hydrogen released atoms from the N-hydrogen bonds with Si dangling bo nds, which occurs because of the dense structures of the films. By subtract ing out this increase due to the recombination reaction, it is found that t he dissociation reaction for the Si-hydrogen bonds is also a first-order re action, and the estimated activation energy is 0.60 eV. (C) 1998 American I nstitute of Physics. [S0021-8979(98)00521-0].