Bulk and interface properties of low-temperature silicon nitride films deposited by remote plasma enhanced chemical vapor deposition

Hydrogenated silicon nitride (a-SiNx: H) films were deposited at temperatur es ranging from 50 to 300 degreesC with remote plasma enhanced chemical vap or deposition (RPECVD) from NH3 and SiH4. The effect of the operating varia bles, such as deposition temperature and especially the partial pressure ra tio of reactant (R = NH3/SiH4) on the properties of the SiNx : H films and the Si/SiNx: H interface was investigated. The NH* radical was dominantly o bserved and the deposition rate was proportional to the NH* radical concent ration. The density of highly energetic N*(2) radicals increased in the hig h plasma power regime in which the film surface was roughened, but they pro mote surface reactions even at low temperature. The refractive index was mo re closely related to the film stoichiometry than film density. The interfa ce trap density is related to the amount of silicon intermediate species an d Si-NH bonds at the Si/SiNx: H interface and it can be minimized by reduci ng the intermediate Si species and Si-NH bonding state. The films showed a midgap interface trap density of 2 x 10(11) - 2 x 10(12) cm(-2). (C) 2001 K luwer Academic Publishers.