关键词: 增强型VDMOS；耗尽型VDMOS；元胞结构；隔离结构；工艺设计

Abstract: Enhancement and depletion integrated VDMOS devices are efficient and low-cost power devices for LED drive circuits. The main problems to be solved in the design and fabrication are the integration of two kinds of VDMOS processes and the isolation between the two devices. Methods of design and manufacture are provided for enhancement and depletion integrated VDMOS devices to get excellent isolation and small chip area in this paper. The area of the depletion mode VDMOS device decreases by 74% when it lies inside the enhancement mode tube compared with lying outside the enhancement mode tube. Test results show that average breakdown voltage BVDSS of enhancement mode tube is 550 V and average breakdown voltage BVDSX of depletion mode tube is 540 V. Average threshold voltage VTH of enhancement mode VDMOS is 3.2 V, and that of depletion mode VDMOS is -3.7 V. The total yield was above 94%. The design has achieved the desired purpose, and the devices have been successfully applied to LED products.

Key words: enhancement mode VDMOS; depletion mode VDMOS; cellular structure; isolation structure; process design