BOW TEMPERATURE PLASMA DEPOSITION OF SILICON-NITRIDE FROM SILANE AND NITROGEN PLASMAS

The plasma enhanced chemical vapor deposition of silicon nitride films from SiH4 and N-2 gases was investigated below 450 K in a helical res onator plasma reactor using in situ spectroscopic ellipsometry and in situ attenuated total reflection Fourier transform infrared spectrosco py. Silicon nitride growth proceeds through nitridation of a thin Si-r ich region at the film surface and the effects of the externally contr olled parameters, such as plasma power and pressure, on the film compo sition and structure can be understood in terms of this mechanism. The key factor that affects the film composition and structure is the act ive nitrogen (N-2*) flux arriving at the surface which determines the nitridation rate of Si-Si bonds. Silicon nitride films deposited using low plasma power and high pressure, conditions that produce low N-2* flux, contains a relatively high concentration of I-I in the form of S i-H and a-Si inclusions. Increasing the power or decreasing the pressu re results in higher N-2* flux and nitridation rate. The films deposit ed under such conditions have less Sill and a-Si incorporation but hig her NHx, (x = 1,2) which disrupts the interconnectedness of the nitrid e network resulting in films that contain voids. Film properties can b e tailored and optimized between these two extremes by manipulating po wer and pressure. (C) 1998 American Vacuum Society. [S0734-2101(98)039 65-0].