Control of slip in horizontal silicon epitaxy with profiled susceptors

The important point in controlling slip in silicon epitaxy is to avoid the build-up of mechanical stress that exceeds the critical value at which the stress is relieved by slip. This critical value depends on the slice perfection and, in particular, is lowered by the presence of local flows. On the other hand, the temperature gradient during the deposition process must be controlled in order to keep the mechanical stress below this critical value. The design of profiled susceptors, to achieve a constant temperature profile across the slice during epitaxy, has been studied. The size and the shape of the pockets are rather critical, and depend on the specific resistivity of the susceptor; the frequency of the rf heating system; the susceptor dimensions; and the slice parameters.