Critical Radial Temperature Gradient Inducing Slip Dislocations in Silicon Epitaxy Using Dual Heating of the Two Surfaces of a Wafer

Heating both wafer surfaces allowed us to efficiently control the radial temperature gradient, d T /d r , even for large wafers (150 mm diameter). With an epitaxial-growth apparatus using dual heating of the two surfaces of a wafer, the relation between inducing slip dislocations and the values of d T /d r were experimentally examined. It was found that it was necessary to keep the maximum temperature gradient lower than between 6 and 11°C/cm in order to accomplish slip-free epitaxy in the temperature ranges of 1100°C to 1250°C and at 930°C, respectively. The maximum shear stresses were calculated for the temperature distributions of each wafer by a finite-element computer model. It was concluded that the critical shear stress (inducing slip dislocations) was between 6×10 6 and 9×10 6 N/m 2 in the temperature range between 1100 and 1250°C and at 930°C, respectively.