Characterization of MOSFET Interface States Using the Charge Pumping Technique

Abstract

In this chapter we present two-level Charge Pumping (CP) as an efficient tool for energetic and spatial interface state profiling of lateral metal oxide semiconductor field effect transistors. We study the accessible energy range, discuss the meaning of CP threshold and flat band voltages and investigate contributions of near-interface oxide traps to the CP current. Different CP techniques are introduced and compared to each other. It is shown that the constant base level CP technique has crucial advantages over the more frequently used constant amplitude technique. It is demonstrated how the CP threshold and flat band voltages of differently doped transistor areas can be determined experimentally from the derivatives of constant high and constant base level CP curves. When subjecting the device to non-uniform Hot Carrier (HC) stress, a characteristic degradation peak appears in the CP derivative. It is shown how one can determine the precise location of the HC induced damage through the application of the so-called constant field CP technique. In the constant field technique the stressed transistor junction is pulsed in phase with the gate terminal using a second pulse generator.