The discovery of a third breakdown: phenomenon, characterization and applications

Abstract

In the history of metal–oxide–semiconductor field effect transistor (MOSFET), the quality of its gate oxide has been a cornerstone of the present semiconductor integrated circuits. The changes of gate dielectrics from conventional SiO2 gate oxide into high-k materials has brought us more challenges in various aspects of transistors, especially the reliability improvement when MOSFET dimension is continually scaled. Depending on the making of high-quality gate dielectrics, it plays a major role for the manufacture of high-end CPU with ultra-low power and low leakage, nowadays. There are two major well-known breakdowns in MOSFET’s history. Not until 2015, a world first observation of the breakdown, different from soft and hard breakdown, named dielectric fuse breakdown, dFuse, was discovered, as a result of CMOS technology moving into the high-k metal-gate (HKMG) era. In this paper, we will introduce from the inception of the Ig-RTN (random telegraph noise) measurement on the understanding of breakdown in 2008 and briefly describe the fundamentals of the RTN technique. Later in 2015, a version 2.0 of this Ig-RTN measurement, named Ig-transient, was successfully developed to delineate the breakdown path in HKMG transistors, from which a third breakdown, named dielectric fuse breakdown, was discovered. Its origin and physical mechanism have been discussed. This breakdown relies on the understanding of a leakage path in the gate dielectric of MOSFET, especially the movement of oxygen ions and the oxygen vacancies in the gate dielectric. Sophisticated measurement technique has also been developed to identify the traps generated in the gate dielectrics which laid the foundations on the understanding of trap generation as a function of time. In the end, two major applications in memories are presented, one is in the use of one-time-programming memory and the other on the understanding of the switching phenomena involved in the operation of resistance random-access memory (RRAM).