Cp. Parry et al., STRUCTURAL AND ELECTRICAL-PROPERTIES OF P(-ENERGY GA+ IMPLANTATION()NJUNCTIONS IN SI BY LOW), Journal of applied physics, 82(10), 1997, pp. 4990-4993
Ultrashallow p(+)n junctions have been formed in silicon by low energy
(5.5 keV) Ga+ implantation into n-type substrates. This avoids the us
e implantation of molecular species such as BF2+ or preamorphization w
ith Ge+ or Si+, which degrade the integrity of p(+)n junctions in meta
stably strained SixGe1-x layers. High resolution secondary ion mass sp
ectroscopy measurements indicate an implant peak at less than 10 nm, e
xcept for postanneal temperatures above 800 degrees C, for which sever
e loss of profile control was observed. Electrical characteristics of
the implanted junctions were determined from diode current-voltage mea
surements and Hall data. At low anneal temperatures, these showed good
rectification behavior, with an ideality factor of 1.1+/-0.1 and a re
verse bias leakage of approximate to 3 mu A cm(-2) in a relatively lar
ge junction area of 5 x 10(-2) cm(2). The electrical properties of the
p(+)n junctions were found to be sensitive to implant dose, improving
with increasing dose. At 580degrees>C, implant doses were achieved th
at were completely activated at levels above previously published Ga e
quilibrium solubility data. For temperatures of 800 degrees C, reverse
annealing occurred, observed as a reduction in carrier concentration
with increasing anneal time and severe profile broadening. (C) 1997 Am
erican Institute of Physics.