DESIGN OF A UHV REACTOR FOR MICROWAVE PLASMA DEPOSITION OF DIAMOND FILMS

A UHV compatible deposition system has been constructed for the growth of diamond films by 2.45 GHz microwave plasma chemical vapour deposition (CVD). The system comprises a loadlock and a spherical deposition chamber where the heated 100 mm diameter substrate is exposed to a reactive plasma environment. The design provides ports for in-situ monitoring by ellipsometry, optical emission spectrometry, mass spectrometry, and laser reflectometry and allows for the later addition of analysis chambers such as XPS. Computer control is provided for all major components and operations, including pumps, valves, gas flows, pressure and temperature adjustment. The system has four pumping groups, two for the main growth chamber providing base vacuum and for pumping the process gases, one for evacuating the loadlock and the fourth for the mass spectrometer. Microwaves enter the chamber via an antenna-based microwave applicator with a water-cooled quartz window. A key feature of this design is the ability to have a free standing ball plasma which touches neither the chamber walls nor the substrate.