NVM cell degradation induced by femtosecond laser backside irradiation for reliability tests

Abstract

In this paper we present the behavior of a single nonvolatile Flash floating gate memory cell when it is irradiated, from the backside, by femtosecond laser pulses. For the first time we show that the memory cell state can change using this type of stimulation. The measurements were carried out with an experimental setup with an ad hoc probe station built around the optical bench. We present the experimental results using different memory bias conditions to highlight the charge injection in the floating gate. Then, we study the cell degradation to check the state of the tunnel oxide and the drain-bulk junction. The aim is to understand the failure mechanisms and use this technique for accelerated reliability tests. Finally we report the experimental results achieved for different laser energies.