一种沟槽-场限环复合终端结构的设计

Design of a Trench-Field Limiting Ring Composite Termination Structure

为了改善硅功率器件击穿电压性能以及改善IGBT电流的流动方向,提出了一种沟槽-场限环复合终端结构。分别在主结处引入浮空多晶硅沟槽,在场限环的左侧引入带介质的沟槽,沟槽右侧与场限环左侧横向扩展界面刚好交接。结果表明,这一结构改善了IGBT主结电流丝分布,将一部分电流路径改为纵向流动,改变了碰撞电离路径,在提高主结电势的同时也提高器件终端结构的可靠性;带介质槽的场限环结构进一步缩短了终端长度,其横纵耗尽比为3.79,较传统设计的场限环结构横纵耗尽比减少了1.48%,硅片利用率提高,进而减小芯片面积,节约制造成本。此方法在场限环终端设计中非常有效。

To improve the breakdown voltage performance of silicon power devices and the flow direction of IGBT currents,a trench-field limiting ring composite termination structure was proposed.A floating polysilicon trench was introduced at the main junction,a trench with dielectric was introduced at the left side of the field limiting ring,and the right side of the trench was just intersected with the transverse expansion interface on the left side of the field limiting ring.The results show that this structure improves the distribution of IGBT main junction current wires,changes part of the current path to longitudinal flow,changes the collision ionization path,and improves the reliability of the device termination structure while increasing the main junction potential.The field limiting ring structure with dielectric slots further shortens the termination length,with a transverse to longitudinal depletion ratio of 3.79,which is reduced by 1.48%compared with that of the traditional field limiting ring structure.The utilization rate of silicon wafers is improved,thereby reducing the chip area and saving manufacturing costs.This method is very effective in the design of FLR termination.