Frequency-modulated charge pumping with extremely high gate leakage

Abstract

Charge pumping (CP) has proved itself to be one of the most utilitarian methods to quantify defects in MOS devices. In the presence of low-to-moderate gate leakage, CP quantification is most often implemented via a series of measurements at multiple frequencies. However, this approach is ill-equipped to handle excessive leakage currents common in advanced technologies. In this paper, we transform multifrequency CP from a quasi-dc measurement into a true ac measurement. This ac detection scheme, called frequency-modulated CP, is far better equipped to deal with high levels of leakage currents and thereby extends the usefulness of CP to current and future device technologies where excessive leakage is the norm. Additionally, we show that multifrequency CP has a long overlooked error that becomes significant in high-leakage situations. We discuss the origins of this error in detail and outline mitigation methodologies. Finally, we explore timing and voltage limitations of waveform generators and how these experimental boundary conditions impact on both frequency-dependent and FMCP.