High Voltage Interconnect Effect Of SOI Lateral Power Devices

The SOI technology have developed rapidly since the 1980's.It has gradually become the mainstream in the field of power integrated circuit PIC since of its advantages of high speed,excellent isolation performance,high integration density,small parasitic effect,low power consumption and strong anti-radiation.Requiring to transfer the signals between device of high side and low side,the high voltage interconnection(HVI)is one of the most important issues in power IC.However,the high electric potential of the HVI metal line can crowd the electric field near the source and lead to the avalanche breakdown occurring prematurely.Thus causes a great degradation in breakdown performance,and affects the reliability of the device.Many efforts have been made to shield the HVI and prevent the plummet of the breakdown voltage,which includes thick insulating film technology,field reduction layer technology,field plate technology and self-shielding technology.In this paper,the novel structures and analytical models of the high voltage interconnection structure are researched.1.The mechanism of the high voltage interconnect structure.The influence of high voltage interconnect effect on the lateral power devices is studied by three-dimensional simulation software DAVINCI.The influence of doping concentration,field plate thickness,SOI thickness,buried oxide thickness and the width of the high voltage interconnect on the breakdown characteristics is analyzed qualitatively.The influences of device parameters on breakdown voltage are investigated.Also,the parameters of the device are optimized.2.Novel analytical models of the high voltage interconnect structure.By solving the Three-dimensional(3D)Poisson equation,the analytical models of the surface potential and electric field distribution are established.All the analytical results are verified by the numerical results.3.Novel HVI structure with High-k dielectric pillars.The new structure is characterized by the High-k dielectric pillar which located in the silicon region beneath the HVI.The High-k dielectric pillars can shield the influence of the HVI,modulate the surface electric field distribution caused by the high electric potential of the HVI metal line,and avoid the dive of the breakdown voltage.The discussions are implemented using the 3D device simulator DAVINCI.And an analytical model is also presented to describe the breakdown voltage of the HVI-HK structure.The breakdown voltage of the HVI-HK structure can achieve 390.4V when the drift doping concentration is 7×1015 cm-3,which improves 28% compared with the RESURF device.However,the RESURF device with HVI can only achieve 94.2V,which is 30.88% of the breakdown voltage of the RESURF device.