Method for evaluating degree of crystal orientation in polycrystalline silicon, selection method for polycrystalline silicon rods, and production method for single crystal silicon

摘要

When a plate-like sample 20 extracted from a polycrystalline rod is evaluated, peaks can appear in a φ-scanning chart. The smaller the number of such peaks, and the narrower the half-value width of the peak, the more suitable the polycrystalline silicon rod is as a raw material for producing single-crystal silicon. It is preferable that the number of peaks in the φ-scanning chart is, for both the Miller index planes <111> and <220>, equal to or smaller than 24/cm2 when converted into unit per area of the plate-like sample. It is also preferable that the value obtained by multiplying the peak half-value width by δL=21/2πR0/360, where R0 is the radius of the sample, is defined as an inhomogeneous crystal grain size, and that a polycrystalline silicon rod of which all the inhomogeneous crystal grain sizes are smaller than 0.5 mm is selected as a raw material for producing single-crystal silicon.

主权项

1. An evaluation method of a degree of crystal orientation of polycrystalline silicon by an X-ray diffraction method, the method comprising
positioning a plate-like sample from the polycrystalline silicon, such that a Bragg reflection from a Miller index plane is detected, rotating the plate-like sample in a plane to a rotation angle φ, with the center of the plate-like sample as the rotation center, such that an X-ray irradiation region defined by a slit φ-scans the principal surface of the plate-like sample, creating a chart which indicates dependency of intensity of the Bragg reflection from the Miller index plane on the rotation angle (φ) of the plate-like sample, and evaluating the degree of crystal orientation of the polycrystalline silicon in terms of the number of peaks appearing in the chart.