A microwave plasma system for the deposition of diamond films

Summary form only given, as follows. There has been considerable interest in applying rf plasma to industrial applications such as etching, deposition, sputtering, surface cleaning, and ion implantation for thin film processing. In the effort of making rf plasma sources, the main concerns are the density and energy distribution of the electrons. These are closely related to the frequency and power of the rf source. Thus microwaves have long been considered the ideal source. In this work, a microwave plasma source is designed for the application of chemical vapor deposition of diamond films. Microwaves provided by a magnetron (2.45 GHz 300 W) are fed into a cylindrical cavity through a loop antenna. The cavity can be adjusted to excite the TM/sub 011/ to TM/sub 013/ modes. Using a large cavity (TM/sub 013/ mode) to reduce the power density, the microwave coupling into the cavity is expected to be more efficient. However, in order to use microwave power effectively, only a small portion of the cavity separated by a glass enclosure to keep the vacuum pressure is used as the reaction chamber. Thus the plasma is produced only in the reaction chamber, and the effect of the plasma loading on the microwave coupling is also minimized. The experimental results indeed show that a very stable plasma can be produced, over a large range of incident power levels. A Langmuir probe is inserted to measure the plasma characteristics.