Modeling the Thermal Characteristics of Stacked 2T0C Memory Array Based on InGaZnO4 Thin-Film Transistors

The 2T0C memory array based on InGaZnO4 thin-film transistors (IGZO-TFTs) was proposed as a new architecture of dynamic random access memory (DRAM) due to its extremely low off-current and potential for monolithic 3-D stack. However, the multilayer stacked 2T0C memory array probably brings severe self-heating issue from the thermal crosstalk among layers. In this article, the 2T0C memory array model was built based on the material properties, electron transport characteristics of IGZO, and basic Fourier heat flow equation. According to the proposed electrothermal model, we found that the electron Joule heat in read operation accounts for the main part of heat generation in the whole operation cycle. The thermal characteristics of different stacked 2T0C cell structures will give advanced guidance for the thermal management scheme of 2T0C DRAM configuration. In addition, the temperature rising of 2T0C cell increases the off-state leakage, resulting in severe degradation of the retention time. It partly attributes to that the oxygen vacancies (VO) generate more electrons at elevated temperatures. Moreover, the significance of low density of VO state is emphasized for the temperature stability of 2T0C cell.