Multiple-zone single-mask junction termination extension—A high-yield near-ideal breakdown voltage technology

Abstract

The junction termination extension (JTE) technique of Temple is investigated in detail by computer simulation and experimentally. A multiple-zone JTE can be fabricated with a well-controlled single ion-implantation through a single mask with laterally variable transparencies. Analog I-V trace records of over 40 000 samples were obtained for analysis. By grouping 49 JTE designs onto region of the wafer, the effects of the JTE variations and the material variations are separated. The JTE performance agrees well with the computer results. The multiple-zone JTE of sufficient extension size achieves an essentially ideal breakdown voltage unaffected by even a factor of two in ion-implant dose variations. The JTE performs well on both n- and p-type wafers. A best design has been applied to several lots of power devices, and a yield of 99.5 percent having breakdown-voltage values within 10 percent of the ideal has been obtained. The single-mask technique assures the producibility of this 100-percent guard JTE technology, which consumes only 30 percent of the extension area needed by field rings that, at best, produced about 70 percent of the ideal breakdown voltage.