Patent ID: 7944222

Claim:
A method for obtaining a characteristic electrical property of a test sample by using a probe having a body and at least four probe arms each including a probe tip, said characteristic electrical property including a resistance property, said probe arms extending parallel from said body, said probe including electrical contact points for establishing electrical contact between said probe tips and a test apparatus operable for transmitting and receiving electrical signals to and from said probe tips, said method comprising the following steps: (a) positioning said probe tips in contact with a surface of a test sample, (b) selecting a subset of four probe tips for performing a measurement by applying a current between a first set of two probe tips and determining a voltage between a second set of two probe tips not including any of the probe tips of said first set, and performing said measurement for all combinations of sets of probe tips, (c) establishing a model value of said characteristic electrical property, (d) calculating model data for said characteristic electrical property based on said model value, (e) if said measurement and said calculated model data do not converge, establishing an adjusted model value and repeating step (d) using said adjusted model value, and (f) if said measurement and said calculated model data do converge, extracting said characteristic electrical property from said model data.