| Item type: | Article | ||||
|---|---|---|---|---|---|
| Journal or Publication Title: | Applied Physics A: Materials Science & Processing | ||||
| Publisher: | SPRINGER-VERLAG | ||||
| Place of Publication: | NEW YORK | ||||
| Volume: | 74 | ||||
| Number of Issue or Book Chapter: | 4 | ||||
| Page Range: | pp. 545-551 | ||||
| Date: | 2002 | ||||
| Institutions: | Chemistry and Pharmacy > Institut für Anorganische Chemie | ||||
| Identification Number: |
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| Keywords: | COPPER; DIFFUSION; CONTAMINATION; KINETICS; LIFETIME; IRON; FE; | ||||
| Dewey Decimal Classification: | 500 Science > 540 Chemistry & allied sciences | ||||
| Status: | Published | ||||
| Refereed: | Yes, this version has been refereed | ||||
| Created at the University of Regensburg: | Yes | ||||
| Item ID: | 73046 |
Abstract
We have measured the gettering efficiencies for Cu and Ni of various silicon wafers, such as MeV-boron-implanted p- polished wafers treated with two different implantation doses of 3 x 1013 atoms/cm(2) B and 1 X 10(15) atoms/cm(2) B, respectively. A third kind of wafer was covered with a poly-silicon back side and thermally pretreated before the gettering test to form oxygen precipitates in the ...
Abstract
We have measured the gettering efficiencies for Cu and Ni of various silicon wafers, such as MeV-boron-implanted p- polished wafers treated with two different implantation doses of 3 x 1013 atoms/cm(2) B and 1 X 10(15) atoms/cm(2) B, respectively. A third kind of wafer was covered with a poly-silicon back side and thermally pretreated before the gettering test to form oxygen precipitates in the bulk. The gettering test started with a reproducible spin-on spiking on the front side of the wafers in the range around 10(12) atoms/cm(2), followed by a thermal treatment to redistribute the metallic impurities in the wafer. Then the gettering efficiencies were measured 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 metallic impurities in the wafer with typical detection limits of (5-10) x 10(12) atoms/cm(3). The concentration profiles were compared with concentration profiles found after testing the gettering efficiency of p/p+ epitaxial wafers. Almost 100% of the total intentional Cu spiking was recovered in the boron buried layer for both implantation doses. On the front surface and in the region between the front surface and the buried layer a Cu concentration similar to 20 times higher than on/in p/p+ epitaxial wafers/layers was measured for the implanted specimen. The lower implantation dose led to higher Cu-concentration levels on the front surface compared to the higher implantation dose. The wafer containing a MeV-boron-implanted layer as well as oxygen precipitates and a poly-silicon back side exhibited a Cu distribution of 30/ similar to 0/70%, respectively. Thus, the gettering by poly-silicon exceeded both the gettering effects by the buried layer and by the oxygen precipitates. Ni gettering in MeV-boron-implanted wafers exhibited other characteristics. The gettering efficiency of the buried layer was 65%, while the remaining Ni contamination was equally distributed between the front-side region and the wafer back side. A wafer containing a buried layer obtained by a 1 x 10(15) atoms/cm(3) B dose and oxygen precipitates exhibited 17% of the total Ni contamination in the boron layer, while similar to 80% of the total Ni contamination was gettered by oxygen precipitates. In the case of buried layer/oxygen precipitates/poly-silicon back side the distribution was found to be 13/37/45%, thus exhibiting equal gettering strengths for oxygen precipitates and the poly-silicon back side for Ni contamination. The results were discussed in terms of segregation and relaxation-induced gettering mechanisms including different reaction rates.
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