Epitaxy cold-wall

Figure 5.8. Schematic of cold-wall production reactorfor silicon epitaxy.

ZnS MOVPE cold-wall horizontal reactor Epitaxially cubic phase grown on (lll)Si growth at 400 °C. Without carrier gas, hexagonal a-ZnS of poor morphology and crystallinity 182... 

In a cold wall reactor, the convection regime is mixed. On the one hand, the temperature gradient between the substrate and the walls of the reactor tends to establish a system of natural convection (laminar flow). On the other hand, the flow of gas induces a forced convection (turbulent flow). A laminar flow is necessary to ensure a good uniformity of the epitaxial film thickness. 

The first 3C-SiC deposition experiments were performed using the LPCVD cold-wall reaction system introduced in Section 3.2. The porous Si samples (10-15 % porosity) were processed at the University of Pittsburgh from n-type Si (100). The samples were then cleaned using the standard RCA cleaning method [15] before the epitaxial deposition took place. 

The growth of 3C-SiC on porous 3C-SiC took place in the cold-wall reactor. This was essentially a homo-epitaxial growth process. Therefore, the etching and carbonization steps were not needed. 

The growth of 3C-SiC on porous Si using the cold-wall LPCVD method resulted in a slightly better film quality compared with that on standard Si, as determined by LTPL. Further improvement in film quality was obtained by growing on a stabilized porous Si substrate. The epitaxial films did contain TBs and APBs at the interface, which is common due to the 20 % lattice mismatch between Si and SiC. 

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