HYBRID-EXCITATION CHEMICAL VAPOR-DEPOSITION OF SILICON-NITRIDE ON (100)SI - THE FILM AND INTERFACE PROPERTIES

Silicon nitride (SiNx) films are deposited on (100)Si substrates using silane (SiH4) and ammonia (NH3) gases by a hybrid-excitation chemical vapor deposition (hybrid-CVD) method at 280-degrees-C. In the deposition, the NH3 gas is decomposed by a radio frequency (13.56 MHz) discharge plasma, and is irradiated by 184.9-nm and 253.7-nm ultraviolet rays with SiH4 gas. The depositions are performed with emphasis on the gas flow ratio, NH3/SiH4, ranging from 3.3 to 29. The effective trapped carrier density at the interface between the SiNx film and the (100)Si substrate is reduced to 2.5 x 10(10) cm-2 by the hybrid-CVD. The films show, moreover, high electrical resistance (e.g. 7 x 10(15) OMEGA cm). These properties are better than those of the conventional plasma-enhanced CVD and photo-enhanced CVD films. The improvement mechanism in the bulk and interface properties is discussed.