This paper presents details concerning such spurious peaks as Fe Ka and Ni Ka radiation, which are often observed in the trace determination of metallic impurities on silicon wafers by using a monochromatic total reflection X-ray fluorescence (TXRF) analyzer. The intensity of a spurious peak varies along with changes in the incident azimuth angle and/or detected intensity of the primary X-ray beam. The origin of this phenomenon is impurities existing along the path of Xrays. This phenomenon influences the accuracy of trace TXRF analysis, and a practical detection limit of a TXRF analyzer becomes worse by approximately one order, becoming 10" atoms/cm2, than the calculated detection limit (2 -8X1010 atoms/cm2) in our case.
The separation measurements of a bulk lifetime υo, front and back surface recombination velocities S0, Sw have been investigated for both 620 μm and 1.08 mm thick Si wafers with various surface treatments. The separation was made by applying bisurface photocoductivity decay method to the photoconductivity decay curves measured by 500 MHz microwave reflection under the bias light illumination. The bulk lifetime and the surface recombination velocities have been determined, respectively, to be 624–659 μs and 18.4–66.1 cm/s for the oxidized sliced-surface and 6285 cm/s for the sliced surface. And they have been also determined, respectively, to be 412–422 μs and <1 cm/s for the oxidized mirror polished-surface or the oxidized etched surface, 565–626 μs and 1042–1112 cm/s for the oxidized sandblasted-surface. The noncontact microwave BSPCD method with bias lights makes it possible to determine separately the bulk lifetime and surface recombination velocities in the front surface and backsurface in Si wafers with the wafer thickness for the practical use.
It is shown that the main peak profiles of monochromatic Total reflection X-ray fluorescence analysis (TXRF) depend very much on the misorientation of the crystallographic [001] axis or the vicinal surface of Si(001) wafer from the crystallographic direction, when TXRF is used for trace analysis of Si wafers. This phenomenon is closely related to the diffraction phenomenon of evanescent beam penetration into a Si wafer under the condition of total external reflection.
A new method using a stylus profiler and a block gauge has been developed
to measure the precise profile of wafer roll off occurred within the edge exclusion
length. The results from the new method have a good agreement of those using the
conventional capacitive gauging tool, when the height deviation of wafer roll off is
measured. The new method can specify the exact lateral position with respect to the
physical edge of wafer.
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