The four-point probe is a metrology tool.
Four-point probe instruments measure sheet resistance of a substrate or thin film. Probes with collinear geometry, such as the one as NFC, pass current between two outer probes and measure the voltage across an inner pair. The resistance is determined from the ratio of the voltage drop to the forced current.
Due to safety and contamination considerations, materials allowed in this tool are restricted. See the list of allowed materials in FOM.
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The Automatic Four-Point Probe System (AFPP) by Superior Electronics is capable of automatically measuring resistivity of a substrate surface. The system utilizes a Fell probe head and a personal computer to control measurements. The system is capable of:
- Handling whole wafers from 3 to 6 inches diameter
- Radial profiling providing 1-2 center readings
- ASTM five-point and nine-point readings
- SEMI five and nine-point, signal radial and multi-radial
- Manual programming of reading points
The AFPP is equipped with a standard spaced 0.050 inch K&S Fell collinear probe head. The AFPP reports can be configured to display various numerical data categories and color mapping of the results. An HP Deskjet printer is available for report printout.
Range: .001 ohm-cm to 1000 ohm-cm, N or P-type
Precision: ± 1.0%
Accuracy: ± 0.05%
Repeatability: ± 0.1%
Layer thickness: 0.3 microns minimum