Doping of Sub-50nm SOI Layers
Bartek J. Pawlak
1
, Ray Duffy
1
, Mark van Dal
1
, Frans Voogt
2
, Robbert Weemaes
3
, Fred
Roozeboom
4
, Peer Zalm
3
, Nick Bennett
5
, and Nick Cowern
5
1
NXP-TSMC Research Center, Kapeldreef 75, Leuven, 3001, Belgium
2
NXP Semiconductors, Nijmegen, Netherlands
3
Philips, Eindhoven, Netherlands
4
NXP Semiconductors, Eindhoven, Netherlands
5
University of Newcastle, Newcastle, United Kingdom
ABSTRACT
Doping of thin body Si becomes very essential topic due to increasing interest of
forming source/drain regions in fully depleted planar silicon-on-isolator (SOI) devices or
vertical Fin field-effect-transistors (FinFETs). To diminish the role of the short-channel-
effect (SCE) control, the Si layers thicknesses target the 10 nm range. In this paper many
aspects of thin Si body doping are discussed: dopant retention, implantation-related
amorphization, thin body recrystallization, sheet resistance (R
s
) and carrier mobility in
crystalline or amorphized material, impact of the annealing ambient on R
s
for various SOI
thicknesses. The complexity of 3D geometry for vertical Fin and the vicinity of the
extended surface have an impact on doping strategies that are significantly different than
for planar bulk devices.
INTRODUCTION
Understanding of dopant behavior in thin body Si is crucial for Fin source and
drain formation.
BOX
Si substrate
As or B implantation
Fin tilt
C-Si or A-Si SOI
Figure 1. Schematic drawings of implants into Fin (a) when source and drain is
formed and of the experiment on implants into crystalline or amorphous SOI
blanket wafer. (b) The tilt angle as indicated is consistent with Fin doping
geometry. The a-Si layer mimics the full Fin amorphizing implant condition.
a b
BOX
FIN
Fin tilt
Mater. Res. Soc. Symp. Proc. Vol. 1070 © 2008 Materials Research Society 1070-E04-06