The Research On Radiation Hardening Technology For 65 NM CMOS SRAM 6T Cell

With the rapid development of space activities, space radiation damage effects in aerospace devices cumulatively attract people’s attention. Even in the ground range, high-energy particles, such as neutrons from coSMIC rays, may cause the logic value of the memory cell flip, which is called single event upset (SEU). Recent studies have shown that, with decreasing size of CMOS technology, the soft error from SRAM cell soft error is rising. Conventional SOI process of strengthening need high design costs, while circuit reinforcement occupy large area. To solve this problem, from the perspective of strengthening layout, this paper researches on the design and implementation of SRAM 6T unit reinforcement measures based on SMIC 65nm bulk silicon CMOS technology. The main works are as follows:Firstly, the mechanism of single event effect is introduced, and the quantitative calculation of single event effects, modeling, simulation methods are discussed; then explain the operating principle of SRAM 6T unit and analyze the mechanism of single-particle impacts on it. Single MOSFET model is created by using Synopsys Sentaurus TCAD tool. According to I/V characteristic of SMIC 65nm MOSFET, I correct the process of corresponding TCAD model. Model the inverter and study the effect of distance on the layout influence single event effect characteristics of inverters; The inverter model after reinforcement is created and simulated by TCAD. The results show that the scheme of guard ring and guard drain for reinforcing inverter is obvious.Finally, on the basis of MOSFET and inverter, the 3D TCAD model of SRAM 6T unit is created; a detailed study on SEU from different layout spacing and layout structure of the SRAM 6T. Then proposed using guarding ring and guard drain to reinforce SRAM based on the inverter reinforcement technology; hybrid simulation are adopted for SRAM 6T unit to quickly verify reinforcement effect, and final results show that the scheme of given anti-radiation is effective. Considering coupling effect, the TCAD model of SRAM 6T unit after reinforcement is created, TCAD simulation results show that proposed layout pattern have the advantage of both stability and area overhead, this anti-SEU pattern is meaningful to SRAM design.