Room-temperature deposition of SiNx using ECR-PECVD for IIIV semiconductor microelectronics in lift-off technique

Abstract Room-temperature deposition of silicon-nitride on InP-substrates for electronic applications is reported. A plasma enhanced chemical vapour deposition apparatus equipped with an electron cyclotron resonance source was used. Molecular nitrogen and silane diluted in helium are chosen as precursors. The dielectric films are defined by means of optical lithography and lift-off technique. C-f measurements reveal a dielectric constant of about 9 and a dissipation factor tan δ = 3 × 10−1 (f = 10 kHz) while the breakdown field is 2 MV/cm (I = 250 μA/mm2). A strong improvement of the dissipation factor by more than one order of magnitude under both electrical and thermal stress, respectively, has been observed which could not be related to a variation of SiH or NH bonds measured by Fourier transformed infrared spectroscopy. The influence of silicon-nitride deposition on the electrical properties of an InAlAs InGaAs heterostructure field-effect transistor is investigated. The most significant change is found as an improvement of gate leakage current by 90% while other dc- and rf-properties remain unchanged.