A prognostic circuit for time-dependent dielectric breakdown failure of MOSFET

With the scaling of feature size, the gate oxide thickness of MOSFET has reduced to several nanometers, and time-dependent dielectric breakdown (TDDB) becomes the one of the main failure mechanisms due to the high electric field strength. Prognostics and health management has become a preferred technology to achieve warning or respond to impending failure of electronic device, in which the "canaries" method could provide advance warning of failure for certain failure mechanism. In the paper, we design a prognostic circuit to monitor TDDB failure of MOSFET based on "canaries" method, and it includes voltage stress generation module, reduced voltage module and output module. The voltage stress generation module is the core part of prognostic circuit for acceleration of TDDB failure, and it is realized by a novel charge pump, which could generate high efficiency voltage relative to the traditional charge pump. The reduced voltage module avoids other transistors in the prognostic circuit under stress state, ensuring the reliability. The prognostic circuit is simulated on the base of the SMIC 0.18 urn CMOS process, and the results show that the new two-stage charge pump can push up to 5 V voltage stress with supply power V_DD=1.8V The prognostic circuit outputs high voltage before the breakdown of the tested MOS capacitor. When the tested MOS capacitor is breakdown, the output of the prognostic circuit turns from high voltage to low voltage, indicating the TDDB failure.