A speed-dependent approach for delta IDDQ implementation

IDDQ test has been widely used in the industry as a DPM (Defects Per Million) improvement tool for test coverage enhancement. It could detect random defects not caught by traditional "stuck-at-fault" functional testing. While effectiveness of traditional IDDQ test is severely affected by the large background current of deep submicron devices, several approaches have been raised on IDDQ-based methodologies to improve its fault detection sensitivity. This paper presents a new methodology based on one of the field approaches, while taking additional results of a specific test sub-circuit that monitored device speed performance into consideration. Dynamic variation due to process distribution is properly reflected via the test sub-circuit, which then leads to consistent fault detection criteria among all IDDQ measurement vectors.