Design And Fabricaction Of Integrated Light Triggered Power Thyristor

Power thyristors have a very wide range of applications in power conversion and control systems in the civil and industrial fields.However,most of the thyristors used are still electronically controlled thyristors.The core part of the few Light Triggered Thyristors that can be used is composed of two dies with different powers as the front and rear stages.The uppermost problems are large power consumption,slow working speed and weak anti-interference ability,which limits their application in the new generation of industrial Internet and The Internet of Things.In response to these problems,this paper designs and develops a Light Triggered Thyristors（Light Triggered Thyristors,LTT）.The driving method is to replace the electronic control with optical control.It not only has all the functions of high repeat peak voltage,low leakage current and low on-resistance of the electronic control thyristor,but also because the optical trigger system is completely isolated from the main circuit.It has higher safety factor and stronger anti-interference ability.The device structure is to replace the dual combination with single integration to obtain more superior device performance.The main work and results of the paper are as follows.1.This article systematically describes the function theory of Light Triggered Thyristors,especially the device physical mechanism such as I-V characteristics,turn-on and block capabilities,off-state critical voltage rise rate,etc.The structural parameters were theoretically analyzed and simulated.2.In order to solve the inherent contradiction between the light penetration depth and the photo-generated current,this paper proposes a design scheme in which the gate structure of the traditional thyristor is removed and the interdigitated cathode structure is removed.After calculation,the light transmission area can reach about 50%.I found a light source with a suitable wavelength（λ=940nm）,redesigned the J₂ junction depth（15μm-25μm）at the main position of the light action,introduced avalanche multiplication mechanism for photo-generated carriers,and found a suitable P region doping concentration of 7×10¹⁵ cm^-31×10¹⁶ cm^-3.In order to solve the inherent contradiction between the dV/dt endurance and the conduction condition,that was introduced from a three-dimensional perspective.The short-circuit structures of three short-circuit points and five short-circuit points are respectively designed to improve the dV/dt tolerance of the device.In order to solve the inherent contradiction between the device structure and the repetitive peak voltage,redesigned the light action position of the device,and found a suitable concentration ratio of P zone to N^-zone.3.For improve the blocking ability of the device,a mesa groove process is added in the process flow.The mesa groove should be a semicircular shape close to 60μm.The materials SIPOS and glass powder are added to the mesa groove.In order to improve the light trigger sensitivity and the basic role of the oxide film,the oxide film process was improved so that the final oxide film thickness of the device was 2350?.4.The characteristic parameters of the device basically meet the design requirements:the forward repetitive peak voltage is greater than 900V,the reverse repetitive peak voltage is greater than 900V,the light trigger sensitivity is only 7mW,the on-time is only 1.5μs,and the leakage current is about 1μA.,The off-state critical voltage rise rate is up to 1400V/μs,and the dark current is pA level.Compared with AQ-H RELAYS Light Triggered Thyristors from foreign Panasonic companies,it shows that the performance indicators of the device developed in this work have reached the expected goals,and have advantages in light trigger sensitivity and on-time.The Integration Light Triggered Thyristors are suitable for mass production.