Aspects of scaling CVD diamond reactors

Among the several techniques available for the synthesis of diamond films the hot filament CVD approach offers some unique advantages in terms of scalability for the deposition of diamond over large area substrates. In this paper some key data that supports the contention that the hot filament CVD process can be readily scaled to deposit high quality diamond films on 300 mm silicon wafers will be presented. The uniformity of wafer temperature has been characterized utilizing an instrumented 300 mm wafer with 12 individual thermocouples attached to the wafer. Temperature variations of < 20 °C across the wafer at a wafer temperature of 895 °C have been achieved. The impact of this is very uniform film quality which has been characterized by Raman spectroscopy. Control over the intrinsic stress in diamond films has been achieved to enable achieving either compressive or tensile stresses in the diamond. Modulating the process variables enables achievement of diamond coated wafers that meet the flatness requirements for the fabrication of advanced semiconductor products utilizing these wafers. This tool and process were developed to deposit thick diamond films, up to ∼40 μm, on 200 and 300 mm silicon wafers.