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1. Four Point Probe
Technique

2. Introduction
The four point probe technique is one of the
most common methods for measuring resistivity.
The four-point probe technique was originally
developed by Wenner in 1916 to measure the
earth’s resistivity. In geophysics it is referred to
as Wenner’s method. In 1954 Valdes adopted
the technique for semiconductor wafer resistivity
measurements.

4. Arrangement
Theclassicarrangementistohavefourneedle-
likeelectrodesinalineararrangement
Thecurrentisinjectedviatwoouterelectrodes
Theresultantelectricpotentialismeasuredvia
innertwoelectrodes

5. Byusingseparateelectrodesforthecurrent
injectionandforthedeterminationoftheelectric
potential,thecontactresistancebetweenthe
metalelectrodesandthematerialwillnotshow
upinthemeasuredresults.Ingeneralthe
material’ssheetresistivitycanbecalculatedby
relation,
ρ=RA/L
R-resistance,L–totallength
A-area

6. Byplacingtheelectrodesatthecenterofthetest
structure,thecurrentwillflowinacirclesymmetrically.
Otherwisesymmetricalcurrentwillnotflowwhenthe
probeswillbeplacedattheedges.Inthiscase,the
resisistivitymesurementswillnotbeaccurate

7. Applications
Used to measure earth’s resistivity
For semiconductor wafers resistivity measurement
To characterize electrolytes
To analyze gases
Resistivitymeasurementsonaluminumteststructures
provideinformationonthelinewidthandthicknessof
theinterconnect
Togetinformationoftheactivechargecarrier
concentrationandtheirmobilitywhichnecessaryfor
doping