Stacking fault annihilation dependence on surface orientation in silicon

Abstract

The annihilation of oxidation-induced stacking faults in silicon wafers with an orientation from 0° to 6° off the [001] axis along the [110] zone has been investigated. The density (DI) of stacking faults on the (111) and (111̄) planes was independent of the surface orientation and can be expressed in the form 1/DI−1/DIO∝t1.34, where DIO is the density in the initial stage of oxidation and t is the oxidation time. The mechanism of this type of stacking fault annihilation can be explained in terms of the unfaulting reaction caused by the impingement of two Frank partial dislocations. A model of the annealing out of the perfect dislocation loops formed by the unfaulting reaction is also proposed. On the other hand, a marked surface orientation dependence was observed in the density (DII) of stacking faults on the (1̄11) and (11̄1) planes. This density can be expressed as DII∝exp(−αt0.4) . The constant α is dependent on the surface orientation. α showed a maximum value of 3.5 h−0.4 for a 3.7°-off-(001) wafer and was nearly zero for a (001) wafer.