An Improved Methodology for Accurate Extraction of Ultra-Low Specific Contact Resistivity of Alloyed Contacts Using Nanoscale Transmission Line Method

An effective transfer length (ETL) model is developed to accurately extract the specific contact resistivity ρ
_c
for alloyed or recessed contacts by accounting for the modification of sheet resistance of semiconductor under the contact (R
_shc
) and uneven contact interface due to the reaction of the contact metal and the semiconductor. This method is applied to an example where the formation of NiGeSn extends into p
⁺
-Ge
_0.95
Sn
_0.05
region to form a recessed contact structure. An ultra-low ρ
_c
of 2.6 ± 0.2 × 10
^-9
Ω-cm
²
is extracted by the ETL model, which is consistent with ρ
_c
of 2.9 × 10
^-9
Ω-cm
²
extracted by the two-layer resistive-network model. The conventional nanoscale transmission line method extracted a ρ
_c
, that is, ~86% higher, which is due to an underestimated R
_shc
. The proposed ETL model can be generally used for ρ
_c
extraction in any alloyed or recessed contacts.