Silicon nitride films were deposited at floating temperature using distributed electron cyclotron resonance plasma enhanced chemical vapor deposition (DECR-PECVD) on Si and InP substrates. The deposition parameters studied included the nature of gases (SiH4-N-2 or SiH4-NH3) and the gas phase composition (SiH4/N-2 or SiH4/NH3). The experimental results establish that to obtain device quality Si3N4, it is desirable to use N-2 instead of NH3 and a high diluted SiH4 gas phase. These process parameters yield to a high resistivity (10(16) Omega cm) and a high critical field (4.5 MV/cm). These properties confirm that the DECR technique is well suited for processing III-V compound semiconductors. NH does not induce such promising characteristics in terms of electrical properties but silicon nitride deposited with this gas is particularly interesting for applications where no stress is required.