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Number 2973
Application Note Using the Ramp Rate Method for Making
Series Quasistatic C-V Measurements with the Model
4200-SCS Semiconductor Characterization System
Introduction
I Capacitor
Capacitance-voltage (C-V) measurements are generally made
using an AC measurement technique. However, some capacitance
Force HI Force HI
measurement applications require a DC measurement technique.
These are called quasistatic C-V (or QSCV) measurements
because they are performed at a very low test frequency, that is,
A
almost DC. These measurements usually involve stepping a DC
voltage and measuring the resulting current or charge. Some of V
the techniques used for quasistatic C-V measurements include
the feedback charge method and the linear ramp method.
The Model 4200-SCS Semiconductor Characterization System
uses a new method, the ramp rate method, which employs two
Model 4200-SMUs Source-Measure Units (SMUs) with two Model Force LO
4200-PA PreAmps. The optional 4200-PA PreAmps are required internally connected
because this test involves sourcing and measuring current in SMU1 SMU2
the picoamp range. The SMUs are used to source current to ForceSMU MeasureSMU
charge the capacitor, and then to measure the voltage, time, and
discharge current. Figure 1. Connections for Capacitance Measurements Using
Ramp Rate Method
The software calculates the capacitance as a function of
voltage from the measured parameters and shows the curve on dQ
C =