RADIATION EFFECTS IN VACUUM-ULTRAVIOLET-IRRADIATED SINX-H FILMS

Photochemistry of vacuum-ultraviolet-irradiated SiNx:H films deposited on Si(100) has been investigated. Irradiation of a hydrogen-rich film at room temperature destroys the incomplete network structure and dec omposes the film into rags because of electronic Si-N bond breaking an d intrinsic tensile stress enhanced by suprathermal heating. Measureme nt of the damaged area by varying the bias voltage applied to the subs trate revealed that the mechanism underlying the damage is localizatio n of multiple holes generated by collision cascade. H atoms from N-H a nd SI-H bonds in interior part of the film are ejected into interstiti als of the network, whereas at the surface they are lost into the vacu um. The N and Si atoms with dangling bonds bind one another, rearrangi ng the SiN network and making the film more dense. Irradiation at temp eratures above 200 degrees C drives a concurrent thermal reaction yiel ding saturated number of species in the film independent of temperatur e.