A New Approach to Threshold Voltage Measurements of Transistors

In this paper an on-line monitoring method for the threshold voltage of MOSFETs is presented. A state space model of the device under test is pre-fitted and used within a particle filter algorithm. The method is capable of extracting the threshold voltage in arbitrary mission or stress conditions. Thus, for reliability assessments the stress does not have to be relieved in order to measure a shift of the threshold voltage. Moreover, the monitoring is able to cancel out certain environmental influences such as temperature and supply voltage fluctuations which is a major improvement for any reliability assessment. The method is evaluated with TCAD (FDSOI Transistor) and SPICE (CMOS Transistor) simulations.