Research Of SRAM Cell Radiation Hardened Method Based On 65nm Bulk CMOS Process

Electronic technology is widely used in modern society.With the decrease of process size,the reliability requirement of electronic technology is increased.The most important part of electronic technology is integrated circuit.Due to the high speed and sensitivity of integrated circuits,they are greatly affected by radiation environment.As the most important part of integrated circuit,memory is vulnerable to radiation environment and produces single event upset(SEU)effect.So the research on memory devices with radiation harden capability becomes extremely important.This paper summarizes the whole structure and basic working principle of SRAM.Then,this paper analyzed several methods of SRAM cell hardening in SEU immune ability.This paper also analyzed the advantages and disadvantages of several radiation harden SRAM structures based on hardening design methods.Two 14T radiation harden SRAM cells(RHU 14T cell and RHB 14T cell)are proposed based on the analysis of existing structures.And the SEU immune ability of these two cells are effectively improved by using source isolation technology.Compared with RHD 12T memory cell,the proposed cells has high write speed and low power consumption.In order to characterize the performances of the proposed RHU 14T and RHB 14T circuits,this paper uses HSPICE simulation.The circuit-level simulations are accomplished in 65nm bulk CMOS technology with 1.2V power supply.The simulation result shows that compared with RHD 12T memory cell,the proposed cells increase-65%write speed and decrease-50%power consumption.Additionally,this paper optimize the SRAM structure and layout-level design.For investigate the optimized design,the continuous normal strike with the LET values at 2 MeV-cm2/mg,5 MeV-cm2/mg,10 MeV-cm2/mg,20 MeV-cm2/mg,40 MeV-cm2/mg,and 80 MeV-cm2/mg has been simulated.The simulation result shows that the proposed cells can remain its data even the LET value equals to 80 MeV-cm2/mg.Besides,in order to evaluate the efficiency of the charge sharing among the off-transistors of the proposed cells,the critical angles are selected by layout.And the simulation result shows that the proposed cells can remain its data with various angles ion strike based on LET equaling to 60 MeV-cm2/mg.