Investigation on the preparation of large area diamond films with 150–200 mm in diameter using 915 MHz MPCVD system

In this work, the diamond films with 150 mm in diameter were prepared in our home-made 915 MHz microwave plasma chemical vapor deposition (MPCVD) system. The appropriate height of the pocketed substrate holder was researched in order to reduce the edge effect as much as possible. And the diamond thin films which were deposited in the designed substrate holder present relative high uniformity which demonstrated the feasibility of the structure of the substrate holder. Furthermore, the φ 150 mm diamond thick film was deposited using relative higher gas mixture flow rate and microwave power. The thickness variation of the diamond thick film is about 13.4% and the full width at half maximum (FWHM) of the diamond peak increases from 5.78 cm−1 to 7.23 cm−1 with the distance to the center of the diamond film increasing from 0 mm to 70 mm. The I(C2)/I(Hα) across the plasma shows a relative uniform distribution which was kept in the range of 2.9–3.4 in our experiments. Besides that, the φ 200 mm diamond film was attempt to synthesis which illustrates the feasibility of depositing the diamond films with the diameter more than 150 mm, although some improvements on the plasma environment should be considered.