Influence of manufacturing variations in IDDQ measurements: a new test criterion

This work presents a new I_DDQ-based test criterion supported bp the characteristics of a set of experimental testing measurements realized over different samples of industrial ICs and by the definition of the corresponding simulation model. Comparing the current consumptions of a specific circuit a significant correlation between measurements can be observed. The current behaviour can be divided into two parts: (1) a circuit dependent one, which has a major contribution, and affects equally all the devices in a given die, and (2) a smaller die dependent fraction due to variations, defective and non-defective, of each of the devices of a specific die. In this paper a current model is defined introducing the effects of manufacturing variations in the basic equations of the sub-threshold current to explain that double behaviour. The results show how it is possible to obtain a lot of information from I_DDQ measurements and how other test selection criteria can be applied to increase the I_DDQ testing sensitivity and quality