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In this paper we calculate throughput based on recipe overhead (chamber etch, wafer load, wafer bake, cool down, unload) and deposition time for "true" SEG or the core cycle time (deposition, purge, etch, purge times) for a CDE process. In the latter case an average, effective growth rate (GR) can be extracted by dividing the deposited thickness per cycle by the cycle time. In high volume manufacturing (HVM) high SEG GR are necessary for high throughput and low Cost of Ownership (CoO). High GR also enable high substitutional carbon levels [C]sub in dilute Si:C alloys. In this work all experiments were exclusively performed using Silcore® (ASM trademarked version of Si3H8). Due to the high GR at low process temperature, high [C]sub and low films resistivities can be obtained independent of the two different Cl containing etch chemistries that were used in this study. The main challenge of using Cl2 compared to the ASM proprietary etch chemistry is the 25-30 times lower etch rate selectivity (~7 vs. ~190) of a-SiCP over epi-SiCP. As a result of the low etch rate selectivity using a Cl2 etch chemistry, a significant portion of the epitaxial SiC:P is also etched with the a-SiCP. This results in a low effective growth rate which has a deleterious impact to throughput.

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Low resistance n+GaN contact materials were experimentally studied for GaN HEMT applications by selective area epitaxy regrowth on a patterned SiC substrate. Epitaxy was performed by metal organic chemical vapor deposition using 100% H2 or 100% N2 as the carrier gas. Thin film characterization demonstrated that n+GaN grown in N2 carrier gas has a superior morphology with improved crystalline quality to that grown in H2 carrier gas. The results also indicated that the surface morphology of n+GaN grown in N2 carrier gas is less sensitive to mask pattern density and micro-loading effects with Si doping concentrations up to 1 × 1020/cm3. Secondary ion mass spectrometry analysis shows that C and O impurity levels in n+GaN are one order of magnitude lower with N2 carrier gas than with H2. The electrical measurement of transmission line model structures shows an n+GaN sheet resistance of 15 Ω/sq and an Ohmic metal to n+GaN contact resistance of 0.02 Ω-mm for structures grown in N2 carrier gas. These values represent 7.1× and 2.5× improvements compared to H2 carrier gas.