Embedded system to characterize bti degradation effects in mosfets

Abstract

A novel system for in-product Bias Temperature Instability (BTI) characterization that allows for characterization of transistor degradation rates is disclosed; it is self-testing and can be embedded in real products without impacting the host functionality. The test data collected during product chip testing (at Electrical Wafer Sort) can be used for identification of abnormal material and for material disposition, or to predict the chip aging rate and premature failure risk due to BTI degradation. The system can also collect the data from the real time device aging in the field, during the host chip operational lifetime. The system is equipped with local programmable power supply generation and self-test capabilities to allow concurrent operations with the host application. The Devices Under Test (DUTs) consist of standard cell-based Ring Oscillators (ROs) which have the unique capability of decoupling the BTI effects on N-type and P-type MOSFET transistors. New switching circuitry is implemented that provides for minimal delay between the stress and measurement phases, thus giving the system the capability of fully characterizing the BTI relaxation dynamic.