Diamond Exploratory and Applied Research Microwave Plasma CVD (DEAR-MPCVD) System

CVD diamond is currently at the forefront of materials technology as it has many applications in quantum technologies, radiation hard electronics and photonics, detectors, sensors, and mechanical wear-resistant applications. Using chemical vapor deposition techniques, thin films of diamond can be grown on a variety of substrate materials and allow tailorable and exciting properties in diamond for a variety of advanced applications. Microwave (2.45 GHz) plasma CVD (MWCVD) reactors are among the most widely used techniques for diamond growth.<br/>Blue Wave Semiconductors has recently introduced the Diamond Exploratory and Applied Research Microwave Plasma CVD (DEAR MPCVD) System. This system allows a large diameter easily exchangeable quartz tube for a dedicated doping application. In this presentation, we report recent advances in the DEAR MPCVD reactor in which microwave power is coupled into the quartz tube chamber to create a turbo (spinning) plasma discharge characteristics useful for surface diffusion of depositing species. The microwaves couple energy into gas phase electrons, which in turn transfer their energy to the gas through collisions and create turbo plasma flow above the substrate leading to the heating and dissociation of the gas molecules, formation of active species, and finally deposition of diamond onto a substrate.<br/>We have designed and developed an optimized microwave cavity supporting larger diameter tube with differential pumping vacuum seals, multiple optical viewports (temperature plasma process and growth monitoring), and a sample stage which creates efficient microwave plasma above the substrate (substrate size up to 12mm x12 mm) with various CH₄/H₂ flow ratios, deposition pressure ranging from 20 Torr to 300 Torr, substrate temperature of 550°C-1100°C for deposition of homoepitaxial (HTHP and CVD single crystal diamond substrates), microcrystalline, nanocrystalline CVD diamond films (on silicon substrates) for a variety of applications. Microwave power from 650 W to 1.0 kW can be used in such systems giving growth rates from 0.2 microns/hr to excess of 10 μm/hr. We will present our systematic studies on the identification of various process parameters, process optimization, and growth of undoped and doped diamond required for radiation-hard devices. Our unique designs and system performance towards emerging applications will be highlighted. The optimization process yielded high-quality polycrystalline films on silicon as well as homoepitaxial films on single-crystal diamond. By using a critically optimized reactor design and process conditions for efficient etching and growth mechanisms, we have obtained high phase purity of CVD diamond without the incorporation of commonly found nitrogen and silicon impurities in CVD diamond films.<br/>We have characterized the films for optical quality and defects using PL, CL, crystalline quality using x-ray diffraction, and surface morphology using SEM. Additionally, boron-doped diamond films have also been characterized by SIMS and electrical characteristics (resistivity, carrier concentration). Selective examples of applications of the DEAR MPCVD system will be emphasized, playing a great role in the exploration of a variety of dopants and novel device developments on a variety of substrate materials. These studies and advances in instrumentation allow us to support our customers for customized and low-cost CVD Diamond systems for innovation, exploration of new dopants and their concentrations, new research and development in diamond and related materials and integration of MPCVD with other deposition and processing techniques for demonstration of integrated diamond power electronics, optoelectronics, and quantum technologies.