Research Of Monolithic Integrated Light-triggered Thyristor

With the rapid development of the new energy industry chain,power semiconductor devices are advancing towards higher efficiency,greater reliability,and lower costs.The Light-triggered Thyristor（LTT）plays a crucial role in power conversion and control due to its high insulation between control and main circuits,as well as its ability to precisely control multiple devices simultaneously.Currently,the intricate configuration of small-scale LTTs hinders their stability and reliability,impeding their potential for highly integrated applications in the future.Therefore,the significance of small-sized LTTs with uncomplicated configuration,well-balanced performance,and cost-effectiveness cannot be overstated as they are pivotal in catering to the needs of sophisticated and high-end applications in the future.In consideration of the application requirements for small-sized LTTs,this thesis conducts research on device physics and proposes a deep junction with light doping in the base area,an avalanche multiplier application,and a concentric cathode shorts layout as key structural characteristics.The numerical simulation reveals the interplay and impact of structural parameters,material parameters,and photoelectric characteristics.Subsequently,by combining the measurement results,the feasibility and superiority of the device design are validated,providing a reference for serialized device design and mass production.The main contents of the thesis are as follows:（1）The device structure and operating principle of the LTT are investigated.Firstly,the fundamental structure,cathode configuration,and terminal arrangement of the LTT are examined,followed by a comprehensive analysis of its basic principles,blocking characteristics,on-state characteristics,and switching characteristics.Secondly,the impact of device structure parameters and material parameters on optoelectronic characteristics is analyzed through their analytical expressions,enabling a comprehensive understanding of the relationship between these characteristics and providing a theoretical foundation for subsequent device design.（2）The proposed monolithic integrated structure of the LTT has undergone targeted design.First of all,for the device structure of the LTT,it is proposed to replace the multi-tube combined structure with a monolithic structure,and integrate the cathode area,light-incident area,cathode shorts and terminal shape on the surface of the die,that is,the monolithic integrated structure.Secondly,the deep junction with light doping base region is proposed as a direct-triggering structure for device characteristics based on a monolithic integrated structure.The feasibility of this approach is demonstrated by analyzing the expression correction of existing blocking characteristics.Based on the deep junction with light doping base region,an avalanche multiplication technique is proposed to enhance the light control efficiency of the device.The feasibility of this technique in monolithic integrated LTT is demonstrated by deriving its critical conditions.Based on the utilization of monolithic integrated LTT with deep junction light doping base region and avalanche multiplication,a concentric circular cathode shorts layout is proposed for the large area light incident window of the device.By deriving the analytical expression of[d V/dt]capability and its influence law with respect to cathode shorts structure parameters,a concentric circular cathode shorts layout is proposed from a macroscopic perspective,which is better suited for small-size and large area light penetration windows in LTTs.Numerical simulations have been employed to validate the efficacy of the monolithic direct-triggering structure,direct light penetration structure,deep junction with light doping base region,avalanche multiplication application,and concentric cathode shorts layout of the LTT.The results obtained from these simulations have been used to summarize their impact on device characteristics and control laws,thus laying a strong foundation for subsequent device fabrication.（3）The key processes of monolithic integrated LTT have been optimized.Firstly,a targeted device fabrication is developed based on innovative design and numerical simulation laws.Secondly,the device characteristics are guaranteed through optimization of several key process technologies.The deep junction with light doping base region is realized using the"two-step diffusion"method,a ring island structure is formed by diffusion to protect the device edge electric field,and the device terminal is achieved by etching the trench and filling with SIPOS.Numerical simulations are utilized to elucidate the optimization effect of pivotal processes and their impact on device characteristics.Finally,various device packaging methods are introduced and the effects of different light incident methods on device characteristics are compared.（4）The optoelectronic characteristics of the monolithic integrated phototransistor are compared and analyzed.Firstly,a characterization scheme is developed based on the performance indexes of the device and the relevant standards of the LTT.Secondly,the device design is verified in terms of blocking characteristics,on-state characteristics,and switching characteristics based on the measurement results of the devices with different designs.The measurement results show that the deep junction with light doping scheme can effectively regulate the blocking characteristics of the device,and the balanced forward blocking voltage(V_DRM)is 1000 V,and the reverse blocking voltage(V_RRM)is 1100 V.The avalanche multiplication effect also significantly improves the photoelectric response process of the device,the light triggering intensity(I_LT)is as low as 3～4 m W/cm²,and the turn-on time(t_on)is as low as 0.4～0.6μs.The switching characteristics of the device are effectively improved with the concentric cathode shorts layout,and the[d V/dt]capability reaches750 V/μs.Finally,the key optoelectronic characteristics of this device are compared with those of similar devices,demonstrating superior balance and performance.