SI3N4 ON GAAS BY DIRECT ELECTRON-CYCLOTRON-RESONANCE PLASMA-ASSISTED NITRIDATION OF SI LAYER IN SI GAAS STRUCTURE/

Si3N4 has been produced on GaAs with low interface trap densities by e lectron cyclotron resonance N-2-He plasma assisted nitridation of a Si layer deposited on a GaAs (100) substrate. Nitridation at 150 and 400 degrees C was monitored by x-ray photoelectron spectroscopy (XPS) and produced stoichiometric Si3N4 The nitride layer thickness, as determi ned from XPS as a function of photoelectron takeoff angle, initially i ncreased rapidly with nitridation time with a transition at a thicknes s of 12-18 Angstrom to slower growth. Capacitance/voltage and conducta nce/angular frequency measurements were performed on metal-insulator-s emiconductor capacitors fabricated from the nitrided samples. The resu lts demonstrated interface trap densities with a minimum of 3.0 x 10(1 1) eV(-1) cm(-2) when nitrided at 150 degrees C. At 400 degrees C the nitridation produced a poor quality interface, which resulted either f rom the higher temperature or from nitridation of all of the Si, leavi ng the Si3N4 in direct contact with the GaAs. (C) 1998 American Vacuum Society.[S0734-211X(98)00302-3].