Resistivity is modified by doping the material. By measuring the material resistivity, the actual doping can also be calculated. A voltage is applied and the current is measured. The film resistance can be calculated and the resistivity is the resistance mutiplied with the surface and divided by the length of the material.
Two characterisation techniques are used in measuring the resistance:
Four point probe
4 probes are applied on a straight line on the surface of the material
2 probes (outside) are used for applying voltage, 2 probes (inside) are used for measuring current
Simple method, does nor require structure formation on wafer
Van der Pauw (see picture)
Requires fabrication of the structure shown below on the wafer,
More precise method
The value of the resistance is:
F(Q) is a factor that depends on the shape of the structure, for a square as in the picture F(Q) =1
Substrate preparation
