SEDL / STP / STP850-EB / STP32667S

A Method to Determine the Initial Phosphorus and Boron Concentrations in Float-Zoned Polysilicon Rods

Chiou, H-D
research specialist, Monsanto Electronic Materials Company, St. Peters, MO

Pages: 11    Published: Jan 1984

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Abstract

A simple method to determine the initial dopant concentrations in polycrystalline silicon rods used in the floating-zone process is described in this paper. The technique is to grow a single crystal in the taper region of the first float-zoned pass. The net carrier concentration, the concentration difference between the donor and acceptor, in the taper region is obtained by four-point probe resistivity measurements. From the slope of the net carrier concentration versus the distance plot in the taper region, the initial phosphorus and boron concentration are calculated. Experimental data show that the calculated values are in good agreement with the frozen-end average dopant concentrations measured on the second-pass zero-dislocation crystals.