Dose- and energy-dependent behaviour of silicon nitride films produced by plasma immersion ion implantation

Schottky devices having guard ring structures were fabricated with conventional silicon processing technology. Nitrogen ions were implanted in contact area silicon at three doses corresponding to low, moderate and high regime. The implantation was carried out employing Plasma Immersion Ion Implantation (PIII) technique at two pulse voltages, i.e. −10 and −20 kV. The dose of nitrogen ions was controlled by changing the frequency of applied pulses. The samples were metallized and patterned to make Schottky contacts. Each sample was divided into two parts and one set was annealed in forming gas ambient at 450 °C. Current–voltage characteristics of the samples showed the change in barrier height. High dose samples at 10 kV pulse energy were found to exhibit characteristics similar to that of metal-insulator-semiconductor (MIS) structures. Thermal annealing in forming gas was effective to eliminate the defects in the p-type silicon samples to a greater extent and to a lesser extent, in n-type samples.