Reliability Research Of 55/50 Nm ETOX NOR Flash

NOR-type flash memory has the advantages of fast reading speed and compatibility with CMOS integration process and is widely used in various fields.More application environments urgently require NOR-type flash memory with larger capacity and smaller size.However,due to the continuous shrinking of feature size,Floating gate devices are gradually approaching the physical size limit,which poses greater challenges to the process and reliability of the memory.In this paper,the reliability and disturb characteristics of 50/55 nm ETOX NOR flash memory and its process optimization are carried out based on the mass production platform.According to the research on the endurance characteristics of NOR flash memory,through TCAD simulation and tape-out test,the channel current density and endurance characteristics are negatively correlated,and the source-drain breakdown voltage(BVDS)and endurance characteristics are positive,and the final selected ion implantation process conditions still need to meet the minimum operating speed requirements,using the wafer acceptance test(WAT)test results I_d and BVDS to study the relationship between the endurance characteristics and the device erasing speed;Finally,by adjusting the ion implantation conditions of the source and drain at the same time,the tape-out test results obtained meet the requirements of endurance times greater than 100k and erasing time less than 500 ms.According to the research on the data retention capability of NOR flash memory,it is found that increasing the critical size of the control gate(CD)can increase the floating gate capacitance coupling ratio,reduce the impact of Vth shift due to charge leakage,and then improve the memory's data retention capability,The final retention characteristic test Vth shift is reduced from0.7 V to 0.4 V,which meets the ten-year retention time requirement at room temperature.According to the research on the disturb characteristics of NOR flash memory,after a large number of device tests and tape-out data analysis,it is found that increasing the thickness of Ni Pt can reduce the Ni Si pipe phenomenon,optimize the influence of the Ni Si pipe phenomenon on the channel electric field,and reduce the Vth shift of the programmed cell due to drain disturb,and improve the memory's anti-drain interference ability.In this paper,the reliability research and process parameter optimization of advanced node ETOX NOR flash memory are carried out,and the research results have been applied in the actual mass production of NOR flash memory.At the same time,this achievement is of great significance to the reliability optimization of floating gate devices at lower nanometer nodes,and has high industrial value.