Effect of mixing of hydrogen into nitrogen plasma

In surface nitriding by plasma, a major concern is to enhance the density o f reactive species of nitrogen. One method is to mix a gas with an ionizati on potential lower than that of nitrogen. The hydrogen gas mixing was carri ed out in an electron cyclotron resonance (ECR) nitrogen plasma. Relative d ensity of molecular ion in the vicinity of a substrate was measured by an o ptical emission spectroscopy. Under a fixed discharge pressure, the densiti es of nitrogen molecular ion (N-2(+)) and excited molecular nitrogen (N-2*) were observed: they have a maximum, when a ratio of hydrogen pressure to n itrogen pressure was 0.5. Silicon nitriding was also conducted by using the nitrogen-hydrogen mixed plasma. In the case of maximum densities of reacti ve species, silicon nitriding was most effective. (C) 2001 Elsevier Science B.V. All rights reserved.