功率肖特基二极管反向EOS量化检测及改善

由于抗反向过压或过流冲击能力不足而导致的功率肖特基势垒二极管(SBD)的潜在失效,会影响电路的可靠性,也是器件制造中最难解决的问题.根据SBD特点和应用要求,给出了静电放电(ESD)、反向浪涌电流冲击、单脉冲雪崩能量三种抗反向过电应力(EOS)能力的量化检测方法.针对三种检测方法的特点,明确了失效机理,并从工艺参数、器件结构等方面给出了解决办法.以2 A 100 V SBD芯片为例,通过器件仿真、流片验证,给出了通过p+保护环结深、p+结浓度、外延层厚度、保护环面积等工艺和结构参数改善ESD、反向浪涌电流冲击、单脉冲雪崩能量的方法.提出了一种p+-p-保护环的结构,可提高功率SBD的抗反向瞬态冲击特性.

Reverse EOS Quantization Detection and Improvement of Power Schottky Diode

Potential failure of the power Schottky barrier diodes (SBDs) due to the lack of anti-reverse overvoltage or over-current impact will affect the reliability of the circuit.It is also the most difficult problem to solve for device manufacturing.Based on the characteristics and application requires of SBDs,three quantitative detection methods of anti-reverse electrical over stress (EOS) capability,such as electrostatic discharge (ESD),reverse surge current and single pulse avalanche energy,were given.According to the characteristics of the three testing methods,the failure mechanism was defined,and the solution was given from the aspects of technological parameters and device structure.Taking the 2 A 100 V SBD chip as an example,through the device simulation and fabrication verification,the improvement methods of ESD,reverse surge current and single pulse avalanche energy for p+ protection ring junction depth,p+ junction concentration,epitaxial layer thickness and protective ring area were given.A p+-p-protection ring structure was proposed,which can improve the anti-reverse transient impact characteristics of the power SBD.