Silicon Substrate Surface Conduction and Dielectric Passivation Fundamentals
Trap-rich polysilicon passivation pins interface charges on high-resistivity silicon, suppressing surface conduction and harmonic spur spikes across RF switches.
High Frequency Capacitance Voltage
Meaning
A diagnostic measurement technique applies a high-frequency alternating signal while sweeping a direct-current bias across a metal-oxide-semiconductor structure to determine dielectric and interface properties. Performing high frequency capacitance voltage sweeps allows engineers to extract parameters like oxide thickness and substrate doping profiles. This test helps verify the quality of thin-film oxide layers.
Signal Behaviour
Alternating current at one megahertz ensures that interface states cannot follow the fast electrical oscillations. During high frequency capacitance voltage testing, only the majority carriers in the semiconductor respond to the alternating excitation. This isolation allows the measurement of the bulk properties of the device without interference from slower defect states, providing a clear picture of the physical structure of the junction.
Parameter Extraction
The resulting curve shows distinct regions of accumulation, depletion and inversion as the direct-current bias changes. Analysis of high frequency capacitance voltage data yields the flatband capacitance and the oxide capacitance. These values are used to calculate the equivalent oxide thickness of the dielectric.
Defect Diagnostic
Comparing the measured curve to an ideal theoretical model reveals shifts along the voltage axis. This high frequency capacitance voltage shift indicates the presence of fixed charges or trapped carriers within the dielectric material.