Papers by Keyword: Chlorosilane

Abstract: The recent explosive growth of Photovoltaics and the relative avidity for silicon of the predominant solar cell technology have resulted in a dramatic change of the polysilicon industry structure. While in the past the polysilicon was manufactured almost exclusively for the semiconductor industry, now more than half of the market is devoted to the solar industry. The different alternative routes to purify silicon for photovoltaic applications are presented in the paper, analysing their advantages and drawbacks. Emphasis is made on the CENTESIL initiative, a new private-public partnership venture promoting a pilot plant that is in an advanced state of construction. The goal is to allow the photovoltaic companies worldwide to count with an independent research centre to help them to establish their own polysilicon plant.

Abstract: Excess carrier lifetimes in 4H SiC epitaxial wafers were characterized by microwave photoconductive decay (o/PCD). The measured decay compromised of surface and bulk recombination curves have fast and slow components. Measured lifetimes are not changed with various surface passivation techniques. High resolution lifetime maps show good correlation with stress birefringence images and lower lifetime around extended material defects like grainboundaries, defect clusters, edge defects and polytype switching bands. Chlorosilane based CVD epiwafers show higher bulk lifetime values than standard silane based CVD materials due to less bulk lifetime defect density.

Abstract: A SiC epitaxy process based on chlorosilane/propane chemistry has been successfully transferred from a single-wafer R&D system to a multi-wafer CVD reactor. The optimized process results in very smooth epi surface (RMS~0.24nm) and minimum surface pits (less than 0.5/cm2). Both n-type and p-type doping in a wide range are demonstrated using nitrogen and aluminum, respectively. The high performance benchmarks for thickness uniformity (intra-wafer variation <1% and inter-wafer variation <1%) and doping uniformity (intra-wafer variation <6% and inter-wafer variation <3%) are achieved on 5 x 3-inch wafers. The carrier lifetime in these epilayers measured by μ-PCD is over 5 μs, the longest value reported so far for SiC epitaxial wafers.

Abstract: Epitaxial growth of SiC films was performed on 4H SiC n+ substrates utilizing a chlorosilane/propane chemistry in both single wafer and batch CVD systems. Variations of the chlorosilane flow under fixed conditions of gas composition, temperature and pressure resulted in growth rates between 4 to 20 μm/hr. Fixing the chlorosilane flow rate to achieve a growth rate of approximately 4 μm/hr, the effects of temperature, pressure and gas composition on background dopant incorporation, epitaxial layer uniformity and epitaxial defect generation were investigated. Intentional n and p-type doping has been demonstrated over the carrier range 1×1018-1×1020/cm3. This paper presents the first reported of use of chlorosilane precursors to grow high quality undoped, n and p doped SiC epilayers.