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The partial pressures of the reactants depend on precursor flow rate, system pressure, and diluent flow (carrier Group IV Materials 17 gas flow). Gas flow velocity (defined by pressure and carrier gas flow) also influences the boundary layer over the wafer surface. In the majority of epi reactors, the susceptor temperature is controlled during the process and can be considered as constant and repeatable (Dutartre, 2001). The wafer rests on a SiC-coated graphite susceptor, and both pieces are lamp heated from both sides inside a cold wall chamber in a gas environment.

2008c). 14) is deposited by quickly ramping up the temperature while maintaining a continuous GeH4 flow rate. Layer thickness profiles up to 350 nm have been verified using X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE). 5 μm have been measured by FTIR. A smooth surface morphology can be maintained if growth conditions are properly optimized. 14). 0 Image statistics Img. Z range Img. Mean Img. Raw mean Img. RMS (Rq) Img. 668 µm Zero cross. 85 Å RMS roughness for a Ge seed layer.

2001). This is a popular technique at IDMs and foundries, which can easily generate test wafers with ion implantation. , using SiH4 or SiCl2H2 (with an α-Si seed). If the precursor (SiH4) partial pressure is well controlled (SiH4 mass flow, H2 carrier flow, and system pressure), this technique allows for matching wafer temperatures between tools by comparing the growth rates and thickness patterns between tools. Also, since the activation energy and the relative thickness change are known, it can be used to determine the proper temperature offsets to obtain a uniform deposition on a nonrotated wafer (T-offset calculator).