A SIMPLE MICROWAVE PLASMA SOURCE FOR DIAMOND DEPOSITION

We describe a simple microwave-produced plasma source that has been co nstructed for plasma-assisted chemical vapor deposition of diamond thi n films. Microwave power from a 700 W domestic microwave oven magnetro n is fed into a water-cooled cylindrical stainless steel vacuum vessel . A methane/hydrogen gas mixture introduced into the vessel is excited by the microwaves to produce a well-defined plasma ball which does no t interact with the walls of the vessel. The position of the plasma ba ll in the vessel can be predicted by cold cavity calculations of the a xial electric field profile. The vessel has several diagnostic ports w hich do not alter its resonant condition. Diamond has been deposited o n various substrates, placed beneath the plasma ball on a graphite-cap ped quartz pedestal. Some of these results are presented and discussed .