Research And Design Of Radiation Hardened MTP Memory In Standard CMOS Process

With the development of the aerospace industry,non-volatile memory is needed in various exploration satellites,manned spacecraft,and space radiators to store configuration data or key information.Traditional non-volatile memory,such as Electronically Erasable Programmable Read-Only Memory(EEPROM)or Flash Memory,generally requires a high voltage of about 15 V in programming and erasing,so there is a higher risk of device breakdown in irradiated environments,as well as higher power consumption.In addition,both EEPROM and FLASH use floating gate structure,which requires additional steps in the process,resulting in higher production costs.In this paper,aiming at the aerospace application field,a radiation hardened non-volatile memory in standard Complementary Metal Oxide Semiconductor(CMOS)process has been designed,also known as Multi-time Programmable(MTP)memory.The MTP memory requires no additional special processes for manufacturing,and the voltage during erasing and programming generally does not exceed 10 V,so it has inherent advantages in terms of process compatibility,cost,power consumption,and radiation hardened performance.This paper focuses on the design of radiation hardened MTP memory,which includes the research of radiation hardened methods,the design of memory array,the design of the peripheral circuit,and the testing of MTP memory.In terms of radiation hardened,measures such as ring gates,epitaxial wafers,and error correction methods have been adopted for the total dose effect and single event effect caused by irradiation.In the design of the memory array,the number of contact holes has been reduced by integrating the gates of four memory cells on a single well,which also greatly reduces the area of the memory array.Secondly,in view of the impact of the total ionizing dose effect on the threshold voltage of the memory cell,a different cell structure has been used in the array.In the peripheral circuit design,a voltage selection circuit with high speed,high accuracy,and wide voltage application range has been designed,which can be applied to the situation where high and low voltage conversion is required inside the MTP memory.Moreover,a data comparison circuit has been also designed to prevent over-erasing and over-programming of memory cells during write operations.In the MTP test work,the best operating parameters of MTP have been obtained by studying the characteristic curves of MTP memory cells after erasing and programming,and the function and radiation performance of the MTP memory has been tested.From the research results of this paper,radiation hardened MTP memory has been successfully designed,with an effective capacity of 144 kbits,which can work between-55℃and 125℃,and the readout time is within 800 ns at 2 V read voltage.The MTP memory cell area is 2.35μm~2,the storage array area is 2.58 mm~2,and the memory area is 3.6 mm~2.Compared with other MTP memories,it has a smaller cell area and overall area.In terms of radiation hardened performance,the total dose resistance of the MTP memory reaches 100 krad(Si),and the single event latch-up resistance threshold reaches 75 Me V·cm~2/mg.According to the available test results,the functionality and performance of the radiation hardened MTP memory basically meet the design requirements.