Influence of electron cyclotron resonance nitrogen plasma exposure on the electrical characteristics of SiNx : H/InP structures

We have studied the influence of nitrogen plasma exposure of the InP surfac e on the electrical characteristics of electron cyclotron resonance deposit ed Al/SiNx:H/InP devices. Nitrogen plasma exposure was performed just befor e the SiNx:H deposition without vacuum breaking. A 30 s plasma treatment at low microwave power (60 W) sharply reduces the minimum of the interface tr ap density, from 4x10(12) to 1.6x10(12) eV(-1) cm(-2) (obtained by the high -low frequency capacitance method). We explain this reduction due to the fo rmation of P-N and/or In-P-N complexes at the InP surface during the plasma -exposure step. These bonds are broken thermally after a rapid thermal anne aling of the device. The minimum of the interface trap density, obtained at the optimum plasma exposure conditions, is among the lowest ones reported in the Literature and similar to those obtained with more complicated proce ssing technologies of the SiNx:H/InP structure. This is a clear indication that plasma exposure in N-2 atmosphere seems to be a valuable and simple su rface conditioning method. (C) 2001 American Vacuum Society.