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91.
We performed measurements of gettering efficiencies for Cu in silicon wafers with competing gettering sites. Epitaxial wafers
(p/p+) boron-doped with a polysilicon back side allowed us to compare p+ gettering with polysilicon gettering. We further
measured metal distributions in p+/p- epitaxial test wafers, with the p- substrate wafers pretreated for oxygen precipitation
to compare p+ gettering with oxygen precipitate gettering. Our test started with a reproducible spin-on contamination in the
1012 atoms/cm2 range, followed by thermal treatment in order to redistribute the metallic impurity. Wafers were then analyzed by a novel
wet chemical layer-by-layer etching technique in combination with inductively coupled plasma mass spectrometry. This led to
“stratigraphical” concentration profiles of the impurity, with typical detection limits of 5–10×1012 atoms/cm3. Twenty-five percent of the total Cu contamination in the p/p+/poly wafer was found in the p+ layer, whilst 75% was gettered
by the polysilicon. Obviously, polysilicon exhibits a stronger gettering than p+ silicon, but due to the large distance from
the front surface, polysilicon was less effective in reducing impurities from the front side of a wafer compared with p+ gettering.
An epitaxial layer p+ on top of p- substrates with oxygen precipitates gettered 50% of the total Cu; while the other 50% of
the Cu was measured in the p- substrate wafer with oxygen precipitates. Without oxygen precipitates, 100% of the spiked Cu
contamination was detected inside the p+ layer. Gettering by oxygen precipitates thus occurs in the same temperature range
as that where p+ silicon begins to getter Cu.
Received: 3 September 2001 / Accepted: 17 October 2001 / Published online: 27 March 2002 相似文献
92.
H. van Pee O. Bartholomy V. Crede A. V. Anisovich G. Anton R. Bantes Yu. Beloglazov R. Bogendörfer R. Castelijns A. Ehmanns J. Ernst I. Fabry H. Flemming A. Fösel M. Fuchs Ch. Funke R. Gothe A. Gridnev E. Gutz St. Höffgen I. Horn J. Hößl J. Junkersfeld H. Kalinowsky F. Klein E. Klempt H. Koch M. Konrad B. Kopf B. Krusche J. Langheinrich H. Löhner I. Lopatin J. Lotz H. Matthäy D. Menze J. Messchendorp V. A. Nikonov D. Novinski M. Ostrick A. Radkov A. V. Sarantsev S. Schadmand C. Schmidt H. Schmieden B. Schoch G. Suft V. Sumachev T. Szczepanek U. Thoma D. Walther Ch. Weinheimer 《The European Physical Journal A - Hadrons and Nuclei》2007,31(1):61-77
Photoproduction of π0-mesons was studied with the Crystal-Barrel detector at ELSA for incident energies from 300MeV to 3GeV. Differential cross-sections
dσ/dΩ, dσ/dt, and the total cross-section are presented. For E
γ < 3GeV, the angular distributions agree well with the SAID parametrization. At photon energies above 1.5GeV, a strong forward
peaking indicates t-channel exchange to be the dominant process. The rapid variations of the cross-section with energy and angle indicate production
of resonances. An interpretation of the data within the Bonn-Gatchina partial-wave analysis is briefly discussed. 相似文献
93.