AVS 59th Annual International Symposium and Exhibition
    Spectroscopic Ellipsometry Focus Topic Monday Sessions
       Session EL+TF+AS+EM+SS+PS+EN+NM-MoM

Paper EL+TF+AS+EM+SS+PS+EN+NM-MoM8
The Ellipsometric Response of Single-Crystal Silicon to Doping

Monday, October 29, 2012, 10:40 am, Room 19

Session: Spectroscopic Ellipsometry for Photovoltaics and Semiconductor Manufacturing
Presenter: H.G. Tompkins, Consultant
Correspondent: Click to Email
The current wisdom is that for ellipsometry in the UV-vis-NIR spectral range, doping of single-crystal silicon can be ignored. We study the ellipsometric response of silicon doped with arsenic at various levels. We also studied the response after implant (before activation) and after the activation (anneal). We find that for samples implanted with 1E18 atoms/cm3, the single-crystal silicon was not amorphized. Implants of 2E19 atoms/cm3 and higher left an amorphous layer on the surface of the wafer the thickness of which was about the depth of the implant. Activation of the sample implanted with 2E19 atoms/cm3 returned the sample to single-crystal silicon and the ellipsometric response in the UV-vis-near_IR is essentially that of undoped silicon. However, the response in the mid-IR is that the extinction coefficient is no longer zero. For samples implanted with 2.5E20 atoms/cm3 and greater, annealing did not return the UV-vis-near_IR ellipsometric response to that of single-crystal silicon. Although this amount of other material (arsenic) is still less that about one tenth of one percent, our conjecture is that the microstructure simply could not be returned to that of a single crystal. As with the lower doped sample, the mid-IR spectral region showed significant increase in the extinction coefficient.