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Distribution and segregation of arsenic at the SiO2/Si interface

Verteilung und Segregation von Arsen an SiO2/Si-Grenzschichten
: Steen, C.; Martinez-Limia, A.; Pichler, P.; Ryssel, H.; Paul, S.; Lerch, W.; Pei, L.; Duscher, G.; Severac, F.; Cristiano, F.; Windl, W.

Fulltext urn:nbn:de:0011-n-767024 (624 KByte PDF)
MD5 Fingerprint: f8445d6f940e23f81de37634c37c8b5a
Copyright AIP
Created on: 29.7.2008

Journal of applied physics 104 (2008), No.2, Art. 023518, 11 pp.
ISSN: 0021-8979
ISSN: 1089-7550
Journal Article, Electronic Publication
Fraunhofer IISB ()
arsenic; interface; pile-up; segregation; silicon

The segregation and pile-up of arsenic atoms at the Si/SiO2 interface in steady state was investigated in detail by a combination of gracing incidence x-ray flu orescence spectroscopy (GI-XRF) measurements, electrical measurements, etching o n the nanometer scale, and measurements of the step heights by interferometry. U sing GI-XRF measurements and removal of the highly doped segregation layer by a sensitive etching process it was possible to distinguish clearly between the pil ed-up atoms and the arsenic atoms in the bulk over a large range of implantation doses, from 3E12 to 1E16 cm−2. The samples were annealed at different tem peratures from 900 °C to 1200 °C for time periods long enough to make sure that the segregation reflects an equilibrium state. With additional step height measu rements at line-space structures, the thickness of the layer with the piled-up a rsenic and the shape of the segregation profile was determined. Electrical measu rements indicated that the segregated arsenic atoms are deep donors with an elec trical activity that increases eventually to full electrical activation for high sheet concentrations of the segregated atoms. The measured data can be modeled as a steady state of neutral arsenic atoms in the segregation layer with positiv ely charged substitutional arsenic atoms and free electrons. For the highest con centration, a saturation of the sheet concentration of segregated arsenic atoms was observed that correlates with the increase in electrical activation. For the use in process simulation programs, a three-phase segregation model was adapted and calibrated.