Characterization and Modeling of Temperature Effects in 3-D NAND Flash Arrays—Part I: Polysilicon-Induced Variability

This paper presents characterization and modeling results exploring the temperature dependence of the electrical characteristics of 3-D NAND Flash strings. Experimental data over a wide temperature range are used to calibrate a Technology Computer-Aided Design model for current transport through the polysilicon channel of the strings, which is then used to investigate the role of grain boundaries on string conduction. Results reveal that the variability in the grain configuration in the strings introduces a nonnegligible statistical spread in the temperature dependence of the threshold voltage (V
_T
) of the memory cells, which acts as a broadening contribution to the array V
_T
distribution when temperature is changed. The experimental and modeling activities will be extended in Part II of this paper to explore the temperature dependence of the V
_T
instability caused by random telegraph noise.