Research On Some Reliability Design Issues Of Biological Micro-nano Electronics

In the past half century,micro-nano electronics technology represented by integrated circuits has changed the world outlook to a great extent.However,two revolutionary changes are taking place in micro-nano electronics technology nowadays.One is from technology to demand.The era of "generation CPU produces generation computer" is gone forever.Integrated circuit chips no longer directly lead the updating of information electronic products,but are closely based on and catering to the needs of users,and highly integrated with other related technologies.The other is to respond to the needs of users.From the three traditional fields of "computer,communication and information processing",the field of application has shifted to the three emerging fields of "health,energy and environmental protection".Compared with the traditional three major fields,the emerging three major fields are the more eternal theme of human development.The future application and development potential of micro-nano electronic technology in this field is immeasurable.In the field of biomedical treatment,micro-nano electronics technology has actually been applied to some extent.By using human implantable chips,we can not only monitor the health status of human organs in real time and continuously,but also intelligently give electrical,chemical and mechanical stimulation to human organs,play the role of disease treatment,dynamic drug delivery and assistant rehabilitation,and even use implantation.Implantable chips replace damaged organs to restore their functions.The core technology of human implantable chip is to realize the miniaturization,low power consumption,low cost and multi-function of hardware.When semiconductor technology gradually enters nano-scale nodes,the reliability issues is increasing.For example,the bioelectric signal is very weak,and the acquisition of bioelectric signal by biochip is more and more prone to signal distortion and difficult to be converted by back-end analog-to-digital conversion.Moreover,because implantable chips need to work in the human body for a long time and cannot be removed or re-implanted frequently,the research on the safe storage of information inside the chips and the anti-aging of integrated circuits has become the key technologies to be tackled in the new reliable design of implantable chips.Aiming at some reliability design issues in biological micro-nano electronics,this papermakes a profound study and gives solutions based on three directions: signal acquisition,information storage and circuit anti-aging.The main work is as follows:1.The high reliability structure of programmable biological neural recording amplifier is studied for embedded chips used in biological micro-nano electronics for bio-electric signal acquisition.According to the requirement and development status of embedded chip for signal acquisition front-end amplifier,a common-source cascode Miller compensation scheme with auxiliary operational amplifier is proposed to improve the stability of low noise amplifier.On this basis,a scheme for reducing leakage of switch is proposed to reduce the influence of MOS switch in programmable capacitive resistance array on the low frequency stability of the system.Finally,a high reliability and low noise programmable neural signal recording amplifier structure design is proposed.The amplifier has a variety of configuration conditions to meet the needs of amplification and filtering of different biological signals,and it is designed and simulated under the manufacturing process of low power supply voltage(1.2V)and 0.18?m standard CMOS analog-digital hybrid integrated circuits to verify the feasibility of the designed circuit structure and the corresponding simulation results are given.The results show that the designed Nerual Recording Amplifier(NRA)has good reliability and meets the needs of bioelectronic systems for the collection and amplification of brain electrical signals.2.Based on the current technological conditions,spin transfer torque magnetic random access memory(STT-MRAM)is used to replace the traditional memory as the memory module of embedded chips.By studying the basic principle of STT-MRAM,it is concluded that STT-MRAM has relatively low storage reliability.On the one hand,it is determined by its own physical and structural characteristics(such as randomness of STT effect and reading interference,etc.).On the other hand,it is caused by the parameter deviation(such as reference mismatch)of the process itself.In addition,the storage reliability of STT-MRAM is also affected by external environment,such as radiation particles and thermal disturbance.The application of error correction code(ECC)technology in STT-MRAM or traditional memory type can effectively improve the reliability of its storage.Therefore,based on the 1T1 MTJ memory cell structure,a new decoding scheme for linear block codes is proposed in this paper.The scheme consists of two decoding layers: advanced error correction layer and asymmetric error correction layer,which are used to deal with multi-bit errors with asymmetric error rate characteristics.Theperformance of the decoding scheme is verified by simulation.The results show that the decoding scheme works well and provides strong technical support for improving the reliability of storage module in embedded chip.3.Aiming at the influence of negative bias temperature instability(NBTI)and process,voltage and temperature(PVT)changes on field effect transistor(FET)in embedded chips,this paper introduces the basic structure of the sense circuit applied in the self-rotating moment-shifting magnetic random access memory(SRMRAM)instead of the traditional memory,and then studies the influence of NBTI effect and PVT effect on the sense circuit in depth.In order to improve the reliability of the sense circuit,a new sense circuit structure based on switching transistor and balancing transistor is designed.Based on the proposed sense circuit,theoretical research and performance analysis are carried out.Using the vertical anisotropic CoFeB/MgO-MTJ compact model and commercial 40 nm CMOS design tool,the hybrid SPICE simulation and Monte Carlo simulation of traditional sense circuit and the new designed sense circuit are carried out.The simulation results show that the sense circuit using switch transistor and balance transistor not only reduces the influence of NBTI on PMOS devices,but also reduces the sensitivity for sense circuit to the change of PVT,effectively reduces the aging effect of integrated circuits and improves the reliability of embedded chips.Through the above research,this paper provides theoretical basis and technical support for the reliability design of biological micro-nano electronics.Although these studies have made some progress and achievements,there are also some shortcomings.The reliability design scheme proposed in this paper is only validated by simulation,and needs to be further validated by tapeout in the follow-up work.