超结硅锗功率二极管电学特性的研究

Research on the Electrical Characteristics of Super Junction SiGe Power Diodes

超结SiGe功率开关二极管可以克服常规Si功率二极管存在的一些缺陷,如阻断电压增大的同时,正向导通压降也将增大,反向恢复时间也变长。该新型功率二极管有两个重要特点:一是由轻掺杂的p型柱和n型柱相互交替形成超结结构,代替传统功率二极管的n-基区;二是p+区采用很薄的应变SiGe材料。该器件可以同时实现高阻断电压、低正向压降和快速恢复的电学特性。与相同器件厚度的常规Si功率二极管相比较,反向阻断电压提高了42%,反向恢复时间缩短了40%,正向压降减小了约0.1V(正向电流密度为100A/cm2时)。应变SiGe层中Ge含量和器件的基区厚度是影响超结SiGe二极管电学特性的重要参数,详细分析了该材料参数和结构参数对正向导通特性、反向阻断特性和反向恢复特性的影响,为器件结构设计提供了实用的参考价值。

The super junction （SJ） SiGe switching power diode which has a columnar structure of alternative p- and n- doped pillar substituting n-base region of conventional Si p＋n-n＋ diode and has far thinner strained SiGe p＋ layer can overcome the drawbacks of existing Si power switching diodes such as the reverse blocking voltage is higher, the forward voltage drop is larger and the reverse recovery time is longer. The most important merit for the SJ SiGe diodes is that they can obtain fast recovery speed, high breakdown voltage and low forward drop at the same time. For the SJ SiGe diode, the breakdown voltages can increase by 42%, the reverse recovery time is shortened about 40% and the forward voltage drop is decreased by 0.1 V （at current density of 100 A/cm2） compared with comparable conventional Si power diodes. Ge content in strained SiGe p＋ layer and the base region thickness are important parameters to affect the characteristics of SJ SiGe switching power diode. Detailed discussions about effects of Ge content and base region thickness on the forward conducting, reverse blocking and reverse recovery characteristics for the SJ SiGe switching power diode are presented, which offer practical references to device manufacture.