Semiconductor wafers of silicon and method for their production
View Patent ↗Semiconductor wafers of silicon are produced by pulling a single crystal growing on a phase boundary from a melt contained in a crucible and cutting of semiconductor wafers therefrom, wherein during pulling of the single crystal, heat is delivered to a center of the phase boundary and a radial profile of a ratio V/G from the center to an edge of the phase boundary is controlled, G being the temperature gradient perpendicular to the phase boundary and V being the pull rate. The radial profile of the ratio V/G is controlled so that the effect of thermomechanical stress in the single crystal adjoining the phase boundary, is compensated with respect to creation of intrinsic point defects. The invention also relates to defect-free semiconductor wafers of silicon, which can be produced economically by this method.
1. A semiconductor wafer of silicon which has neither OSF defects, nor A-swirl defects, nor COP defects with a size of more than 30 nm, with a radial profile of growth striations of oxygen or dopants in which an attitude angle θ between a horizontal line and the tangent applied to the growth striations lies in a range, expressed in degrees, described by the inequality θ<−17×(r/rmax) when the attitude angle θ is determined in a range of from r/rmax=0.1 to r/rmax=0.9, where r is the radial position at which the tangent is applied to the growth striations and rmax denotes the radius of the semiconductor wafer.
2. The semiconductor wafer of claim 1 , wherein the attitude angle θ in the range of from r/rmax=0.1 to r/rmax=0.9 lies without exception in the range of θ<−17×(r/rmax).
3. The semiconductor wafer of claim 1 , wherein the attitude angle θ in the range of from r/rmax=0.1 to r/rmax=0.9 lies without exception in a subrange described by the inequality −50×(r/rmax)<θ<−17×(r/rmax).
4. The semiconductor wafer of claim 1 , further comprising at least one element selected from the group consisting of carbon, nitrogen and hydrogen.
5. The semiconductor wafer of claim 4 , having a nitrogen concentration of from 2.0×10 13 to 1.0×10 15 atoms/cm 3 .
6. The semiconductor wafer of claim 1 , having an oxygen concentration of from 5×10 17 atoms/cm 3 to 6.5×10 17 atoms/cm 3 .