ADVANCED SALICIDES FOR 0.10 MU-M CMOS - CO SALICIDE PROCESSES WITH LOW DIODE LEAKAGE AND TI SALICIDE PROCESSES WITH DIRECT FORMATION OF LOW-RESISTIVITY C54 TISI2
Ja. Kittl et al., ADVANCED SALICIDES FOR 0.10 MU-M CMOS - CO SALICIDE PROCESSES WITH LOW DIODE LEAKAGE AND TI SALICIDE PROCESSES WITH DIRECT FORMATION OF LOW-RESISTIVITY C54 TISI2, Thin solid films, 332(1-2), 1998, pp. 404-411
The scaling of CMOS technologies to 0.10 mu m and beyond imposes incre
asingly demanding constraints to self-aligned silicide (salicide) proc
esses. For high performance devices, it is essential that salicide pro
cesses achieve low gate and source-drain sheet resistance as well as l
ow silicide to source-drain diffusion contact resistance, and maintain
low junction leakage. This becomes increasingly difficult as junction
depths and linewidths are scaled. In this paper we present an overvie
w of the development of advanced Ti and Co salicide processes, with im
plementations into a high performance 0.10 mu m complementary metal-ox
ide-semiconductor (CMOS) technology. For Co salicide, the main scaling
issue is diode leakage on shallow junctions. We show that the use of
pre-amorphization implants or a pre-Co deposition sputter etch improve
s diode leakage distributions, but fails to eliminate high leakage out
liers. Co deposition temperature and rapid thermal processing (RTP) va
riables were found to have a strong effect on diode leakage with optim
ization of either one resulting in tight low leakage distributions on
shallow junctions. For conventional Ti salicide processes, the main sc
aling issue is sheet resistance on narrow lines due to incomplete high
resistivity C49 TiSi2 to low resistivity C54 TiSi2 transformation. We
present X-ray diffraction (XRD) and high resolution transmission elec
tron microscopy (HRTEM) studies that indicate that direct growth of C5
4 TiSi2 bypassing the C49 phase is achieved at low temperatures on pol
ycrystalline or amorphous Si with the addition of Mo impurities, elimi
nating the narrow line effect. The mechanism is demonstrated to be nuc
leation of MoSi2 and an unidentified phase at the Ti/Si interface, fol
lowed by epitaxial growth of C54 TiSi2 on these templates. Ti salicide
processes with Mo impurities were evaluated, demonstrating an optimiz
ed one-step RTP process combining Mo and pre-amorphization implants th
at maintains low sheet resistance to 0.06 mu m gate lengths. Successfu
l implementations into a 0.10 mu m flow were achieved both for optimiz
ed Co salicide or Ti salicide processes. (C) 1998 Elsevier Science S.A
. All rights reserved.