Origin and suppression of misfit dislocations in heavily boron-doped (100) silicon wafers

It has been found that misfit dislocations in heavily boron-doped layers originate from wafer edges. Moreover, the propagation of the misfit dislocation into a region can be suppressed by placing a surrounding undoped region formed by a chemical-vapor deposited (CVD) oxide ring pattern before boron doping. A heavily boron-doped layer with no misfit dislocations can be obtained by using a CVD oxide ring up to a boron dose of 5.4×1016 cm2 for an area of 2 cm×2 cm and up to a dose of 1.48×1017 cm2 for an area of 400 μm×400 μm.