Design And Implementation Of Low Dose Rate Radiation Hardened Bipolar Transistors

Bipolar devices and integrated circuits working in space radiation environment are seriously degraded by ionizing radiation,especially low dose rate ionizing radiation,which greatly limits the service life of space electronic system.How to improve the resistance of electronic components and integrated circuits to the damage caused by the cumulative effect of low dose rate ionizing radiation plays a very important role.So far,there is no unified and clear model on the mechanism of low dose rate radiation damage enhancement effect(ELDRS).In engineering,how to improve the resistance of bipolar devices and analog integrated circuits based on bipolar devices to low dose rate radiation damage is a bottleneck to be solved.This thesis focuses on bipolar devices and integrated circuits from process evaluation,radiation hardening technology,radiation test and other aspects.The details are as follows:1.In this thesis,the radiation effects of typical devices of five commercial bipolar process platforms commonly used in a domestic process line are comprehensively tested.The results show that all kinds of processes have obvious enhancement effect of low dose rate ionizing radiation damage.Relatively speaking,the normalized current gain of NPN transistors with 40V SOI complementary bipolar process is the smallest,the vpnp transistors with 40V SOI complementary bipolar process and 12V complementary bipolar process have strong radiation resistance,and the radiation enhancement effect of each transverse PNP transistor is the strongest,which needs to be studied and improved.2.This thesis focuses on the design and process implementation of radiation hardened bipolar devices.Combining radiation damage mechanism with device structure,working principle and process technology,three solutions were designed from the aspects of device structure optimization design,process condition optimization and new material application,and chips fabricated and sample tests were carried out.Among them,solution C is improved in many aspects,such as optimizing the doping concentration distribution in the base region,reducing the thickness of the oxide layer above the base region,and improving the process quality of the Si-SiO₂ interface.The experimental results show that NPN and LPNP transistors function normally after low dose rate total dose ionizing radiation,and achieve the design goal.3.The new bipolar device are applied to the design of an operational amplifier,and the correctness and feasibility of the technical solution are verified through chip fabrication,sample preparation and two rounds of irradiation tests.Compared with the imported commercial ICs,the device and circuit designed in this paper have a certain ability to resist ELDRS radiation.After the 0.1 rad(Si)/s radiation,the parameters of op amp sample with substrate PNP input are still within the specification limit,although they change greatly.However,there is still a big gap from the requirements of very low dose rate radiation hardened in space environment,which needs to be further improved.In this paper,new kind of bipolar devices and op amp IC are designed and implemented,and the experimental results show that the goal of this paper is achieved.Although the sample is still far away from the practical application of space engineering,the research process and method have a certain engineering reference value,which lays a solid foundation for the subsequent development of bipolar devices and analog integrated circuits for low dose rate radiation hardened in space environment.