ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
PtSi contacts to As-doped polycrystalline silicon have been studied with respect to dopant redistribution, microstructure, and contact resistance. Arsenic was found to pileup at the PtSi-polysilicon interface upon silicide formation. Cross-sectional transmission-electron microscopy revealed columnar PtSi grains and a relatively flat interface between PtSi and polysilicon. These observations are similar to those reported for the case of PtSi formed on the single-crystal silicon. The specific contact resistance (ρc) has been investigated as a function of As concentration ranging from 8×1019 to 2×1021 cm−3 and of its dependence on substrate preclean procedures prior to Pt deposition. It was found that ρc decreases with increasing As concentration, as expected from theory. However, the contact resistance to As-doped polysilicon is about ten times higher than contacts to similarly doped single-crystal Si. The origin of this difference is attributed to the fact that not all of the implanted As was activated. Hall-voltage measurements showed that only about 10% of the implanted As was electrically active after an 880 °C, 20 min furnace annealing. Rapid-thermal annealing was then used to activate a higher fraction of the implanted As. Consequently, a much lower ρc was obtained: e.g., 7.5×10−8 Ω cm2 for samples annealed at 1050 °C for 30 s, in contrast to a value of 8.4×10−7 Ω cm2 for a furnace-annealed sample.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.340016
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