Determination of oxygen concentration profiles in silicon crystals observed by scanning IR absorption using semiconductor laser

Abstract

Concentration profiles of interstitial oxygen in silicon crystals were determined by scanning IR absorption using PbTe-Pb0.82Sn0.18Te semiconductor laser with the wavelength of 9.04±0.02 μm. IR beam was collimated to be 200 μm in diameter. Czochralski-grown crystals showed a local concentration fluctuation of about 1.8×1017 cm−3 from the average of 1.1×1018 cm−3. This fluctuation corresponds to an oxygen striation in the silicon crystal.

<title>Improvement of optical method of oxygen-in-silicon characterization and design consideration in measuring setup for detailed nondestructive mapping of interstitial oxygen</title>

“…2(b)), assuming globar (whose emissivity is close to 1 in the spectral band of interest) to be such a source, thus providing "fair" comparison of the two schemes. Using series (A12a) for $T(Tk:), one obtains L = LBB(X, Tsoce) ) = LBB(X, T50) (0.539 _ 0.645 i), (4) while sensitivity of the considered scheme is S Li = -0.645 LBB(X, Tsource). (5) Thus, the value of SL1'5 to ratio is determined by disparity ofradiant bodies' temperatures; assuming T33O.…”

“…Investigations tempered due to lack of adequate measuring instruments. For example, most widely spread -optical method of non-destructive measuring of 0-in-Si concentration based on ASTM F95 1-96 standard [3] is characterized by locality of about 7 mm, whereas estimations based on known parameters of oxygen in silicon lattice and on the data of several, not numerous experimental works [4,5] leads one to conclusion that sub-millimeter -up to 30.50 tm for the finest details -resolution should be implemented for the entire wafer surface (with today wafer diameter of 200 mm and more). Unfortunately, none of the known methods may be directly used to solve the problem.…”

Oxygen striation and thermally induced microdefects in Czochralski-grown silicon crystals

“…Ohsawa, K. Honda, S. Ohkawa, andK. Shinohara Fujitsu Laboratories Ltd., 1015 Kamikodanaka, Nakahara, Kawasaki 211, Japan (Received 6 March 1980; accepted for publication 7 May 1980) Oxygen striations in Czochralski-grown silicon crystals have been directly observed by applying the scanning IR absorption technique to longitudinal sections.…”

“…The results show that oxygen plays a very important role in microdefect formation. A critical oxygen concentration for microdefect introduction was estimated to be (7)(8) X 10 17 cm-3 for 96-h, 600 ·C heat treatment.…”

“…Other details and the spectroscopy system were reported in a previous letter. 7 The measurements were carried out on the as-grown longitudinal sections. Figure 2 shows the result of scanning IR absorption measurements along line 2, which is parallel to and 15 mm from the growth axis, as shown in the inset.…”