<title>Defect-free IDDQ with reverse body bias</title>

Abstract

Systematic investigations on defect-free IDDQ in deep sub- micron CMOS with reverse body bias were performed by SPICE simulation to improve resolution of IDDQ measurement. Effects of reverse body bias on off-state leakage of scaled CMOS devices and IDDQ of typical CMOS circuit cells were investigated. It was found that reverse body bias could effectively reduce worst case defect-free IDDQ of typical circuit cells by more than one order in magnitude for technology generation down to 0.18 micrometer. The reduction in worse case defect-free IDDQ is enhanced as the device temperature goes up and diminished as the temperature goes down. Further investigation showed that reverse body bias also made the defect-free IDDQ less sensitive to the input state; therefore one single IDDQ current threshold might still be used for IDDQ testing down to 0.18 micrometer technology generation. It was found that there might exist an optimal reverse body bias that minimizes the defect-free IDDQ current. The optimal reverse bias value decreases as the temperature goes down and might vary from circuit to circuit, process to process, and technology generation to generation.