DocumentCode :
1115520
Title :
Modeling and measurement of contact resistances
Author :
Loh, William M. ; SWIRHUN, Stanley E. ; Schreyer, Tim A. ; Swanson, Richard M. ; Saraswat, Krishna C.
Author_Institution :
Stanford University, Stanford, CA
Volume :
34
Issue :
3
fYear :
1987
fDate :
3/1/1987 12:00:00 AM
Firstpage :
512
Lastpage :
524
Abstract :
This paper presents a generalized model of ohmic contacts and a unified approach for the accurate extraction of specific contact resistivity (ρc) for ohmic contacts from measured contact resistance using the cross bridge Kelvin resistor, the contact end resistor, and the tranmsission line tap resistor test structures. A general three-dimensional (3-D) model of the contacts has been developed from the first principles and has been reduced to 2-D, 1-D, and 0-D (one lump) models with the necessary approximations. It is shown that the conventional I-D models overestimate the value of ρcbecause of the parasitic resistance due to 2-D current flow around the periphery of the contact window. Using 2-D simulations, we have accurately modeled the current crowding effects and have extracted accurate values of ρcindependent of contact size and the test structure type. A theory of scaling of contacts has been developed and is applied to commonly used structures. A universal set of curves has been derived for each particular contact resistance test structure and, given the geometry of the structure, these allow accurate determination of ρc, Without the actual use of the 2-D simulator. Experimental and theoretical accuracy of the three test structures has been compared. Accurate values of ρcfor various contact materials to n+and ρ+Si have been determined. The data confirm that in the past researchers have overestimated ρc, and that ρcwill not limit device performance even with submicrometer design rules.
Keywords :
Bridges; Conductivity; Contact resistance; Electrical resistance measurement; Geometry; Kelvin; Ohmic contacts; Proximity effect; Resistors; Testing;
fLanguage :
English
Journal_Title :
Electron Devices, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9383
Type :
jour
DOI :
10.1109/T-ED.1987.22957
Filename :
1486668
Link To Document :
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