W. Fukarek et al., ELLIPSOMETRIC INVESTIGATION OF DAMAGE DISTRIBUTION IN LOW-ENERGY BORON IMPLANTATION OF SILICON, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 127, 1997, pp. 879-883
As the scaling of silicon devices to 100 nm channel length requires th
e formation of ultra-shallow (< 60 nm) junctions, high depth resolutio
n analytical techniques become necessary for the characterization of t
he dopant and damage distributions. In situ single wavelength Ellipsom
etric Etch Depth Profiling (EEDP) and non-destructive Variable Angle o
f incidence Spectroscopic Ellipsometry (VASE) have been used to obtain
accurate and quantitative information on the depth profiles of radiat
ion damage produced by low energy, room temperature ion implantation o
f B+ into Si. Implantation energy ranged from 250 eV to 10 keV and the
dose was in the range 5 x 10(14) B+ cm(-2) to 5 x 10(15) B+ cm(-2). E
EDP has been applied to damage depth profiling of low energy implanted
silicon for the first time. The range and shape of the damage distrib
utions obtained from optical model calculations are in good agreement
with TRIM calculations for the energy range investigated. However, for
the 10 keV implant, EEDP results unambiguously show the presence of a
6 nm thick amorphous silicon layer at the surface which is not predic
ted by TRIM. In the case of the 250 eV implant the presence of an amor
phous Si surface layer can not be inferred from VASE data analysis alt
hough the existence of a 1 nm thick amorphous Si surface layer is indi
cated by EEDP.