Push-Pull型pFLASH开关单元结构设计及特性

Structure Design and Electrical Characteristics of the Push-Pull pFLASH Switch Cells

基于90 nm eFLASH工艺设计并制备了一种新型抗辐照Push-Pull型pFLASH开关单元,并对其特性进行了研究。该结构由2个2T-FLASH管（T1/T2）和1个信号传输PMOS管（T3）组成,采用带带隧穿（BTBT）编程方式和福勒-诺德海姆（FN）擦除方式实现其＂开/关＂态功能。同时,对其＂开/关＂态特性进行表征,研究其耐久性和电荷保持特性,最后,对其抗总剂量（TID）能力进行评估。实验结果表明：该器件的＂T1编程-T2擦除＂与＂T1擦除-T2编程＂态均可以实现信号传输管的＂开/关＂态功能,其阈值窗口的均值约为10.5 V;在工作电压为-1.2 V条件下,T3管的＂开＂态驱动电流均值约为0.92 mA,＂关＂态漏电流低于40 pA,且均表现出了良好的一致性。同时,该器件的循环擦/写次数可达10 000次,在25℃的＂开/关＂态应力条件下寿命大于10年,抗总剂量能力可达150 krad（Si）以上。

A new type of radiation-hardened Push-Pull pFLASH switch cell which includes two 2 TFLASH transistors（ T1/T2） and a signal transmission PMOS transistor（ T3） was designed and prepared based on 90 nm e FLASH process technology and its performance was studied. The ＂on/off＂states function was realized by using the band-to-band tunneling（ BTBT） programming mode and Fowler-Nordheim（ FN） erasing mode. Meanwhile,the ＂on/off＂states characteristics were characterized to study the endurance and retention of the p FLASH switch cell device. Finally,its resistance to total ionizing dose（ TID） ability was evaluated. The experimental results show that＂T1_PGM-T2_ERS＂and ＂T1_ERS-T2_PGM＂states of the device can achieve the ＂on/off＂states function of the signal transmission transistor.The average threshold windows of T1/T2 transistors are approximately 10. 5 V. Under-1. 2 V working voltage,the average driving current of the T3 transistor at ＂on＂state is about 0. 92 m A,and the leakage current of T3 at ＂off＂state is below 40 p A,which shows a good uniformity. Meanwhile,the erasing/writing cycles of the device can reach 10 000. The lifetime of the device is more than 10 years under the ＂on/off＂states stress condition at 25 ℃,and the ability of TID radiation can reach above 150 krad（ Si）.