ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Previous investigations have reported substrate tilt and azimuthal (twist) orientations for bare, single-crystal gallium arsenide (GaAs) targets that control channeling-induced device parameter nonuniformities in variable scan angle (electrostatically scanned) ion implanters. However, those results were obtained using 2-in. (50.8 mm) and 3-in. (76.2 mm) diam GaAs substrates. Concern remains over whether the orientations reported will adequately control these nonuniformities when GaAs substrates with greater than 3-in.-diam are implanted. In this study implant profile and pinch-off voltage (Vp) dependence on twist orientation angle with a fixed 10° tilt along 150-mm-diam of bare GaAs targets are measured. Shottky capacitance-voltage measurements are employed to examine channeling-induced variations in Vp and electron concentration profiles for 29Si+ implantation at 100 and 60 keV. It is concluded that 10° tilt is not generally adequate to avoid the effects of planar channeling across the full diameter of bare GaAs wafers ≥100 mm. An analysis employing a stereographic projection, combined with data from this investigation, indicates that, in order to obtain optimum control over implant depth profile variations across large diameter (≥100 mm) GaAs wafers implanted with electrostatic scanning, the use of tilt angles (approximately-greater-than)10° (perhaps 12°–15°) may be required.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.351107
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