Design and Evaluation of a High-accuracy Measurement System for Sheet Resistance of Thin Films

Inspection and measurement for the sheet resistance and resistivity play a pivotal role in the semiconductor industry. In this study, a high-accuracy measurement system for sheet resistance of thin films was designed based on dual-measurement with four-point probe method. The measurement system was composed of a special switching circuit, a digital output module, Keithley 2400 SourceMeter, and a computer running LabVIEW. The special switching circuit designed based on the multiplexer played an important role in current probes and voltage probes automatic switching under the control of virtual instrumentation software LabVIEW and National instruments digital output module hardware NI 9401. Keithley 2400 SourceMeter controlled by LabVIEW was used for two-times high-precision voltage measurement. Van der Pauw correction factor were calculated based on the results of the two-times voltage measurement. Then the sheet resistance of thin films was calculated by LabVIEW software's powerful computing. The experimental results show that the designed and developed system can meet the needs of fast on-line measurement of thin films' sheet resistance with a wide range, and moreover, the accuracy of measurements and the level of automatization have been dramatically improved compared to the conventional measurement system.