4H-SiC npn双极型晶体管的研制

采用国产的4H-SiC外延材料和自行开发的SiC双极晶体管的工艺技术,实现了4H-SiC npn双极晶体管特性。为避免二次外延或高温离子p+注入等操作,外延形成n+/p+/p/n-结构材料,然后根据版图设计进行相应的刻蚀,形成双台面结构。为保证p型基区能实现良好的欧姆接触,外延时在n+层和p层中间插入适当高掺杂的p+层外延,但也使双极晶体管发射效率降低,电流放大系数降低。为提高器件的击穿电压,在尽量实现低损伤刻蚀时,采用牺牲氧化等技术减少表面损伤及粗糙度,避免表面态及尖端电场集中,并利用SiC能形成稳定氧化层的优势来形成钝化保护。器件的集电结反向击穿电压达200 V,集电结在100 V下的反向截止漏电流小于0.05 mA,共发射极电流放大系数约为3。

Study of 4H-SiC npn Bipolar Junction Transistor

The characteristics of 4H-SiC npn bipolar junction transistor were realized on the homemade 4H-SiC epitaxy material and own technology of SiC bipolar junction transistor.In order to avoid high temperature p+ ion implantation or overgrowth,n+/p+/p/n-epitaxy was used,which is etched to form double-mesa-structure.For good p-base contact,p+layer was inserted between the n+ and p layer,which debased the emitter efficiency and the current gain at the same time.In order to increase the breakdown voltage of device,sacrifice oxygenation was used,which can reduce the etch damage and avoid electric field focus,and SiO2 formed by oxygenation of SiC supply device passiwation,too.Based on aforementioned,4H-SiC npn bipolar junction transistor is realized with a BVcbo of 200 V and a current gain of 3,and the leakage current is lower than 0.05 mA at BVcbo of 100 V.