Summary
International Technical Conference on Circuits/Systems, Computers and Communications
2008
Session Number:P2
Session:
Number:P2-75
Characteristic Enhancement of Trench IGBT by Deep P+ Layer beneath the Trench Emitter Ion Implantation
Sin Su Kyoung, Jae In Lee, Jong-Seok Lee, Ey-Goo Kang, Man Young Sung,
pp.-
Publication Date:2008/7/7
Online ISSN:2188-5079
Summary:
The Trench Insulated Gate Bipolar Transistor (TIGBT) was invented for lower on-state voltage drop and higher integration due to smaller cell pitch, but TIGBTs suffer from breakdown voltage degradation due to the concentrated electric field at the corner of the trench gate in the forward blocking state. In this paper, we report on a new TIGBT structure that solve this problem. The proposed structure has a deep P+ layer beneath the trench emitter to distribute the concentrated electric field at the trench gate corners in the forward blocking state. The deep P+ layer of the structure is formed by ion-implantation at the bottom of the trench after partial etching of the P-base region. The electrical characteristics of the proposed IGBT structure are verified by device simulation, namely, MEDICI and TSUPREM. The proposed structure improves the breakdown voltage compared to conventional TIGBTs without changing the threshold voltage and the on-state voltage drop. The distribution of the electric field is also changed by its design parameters. When the depth of the trench gate corner and the deep P+ layer are the same, the breakdown voltage is at the highest point. As the gap distance between the trench the gate corner and the deep P+ layer gets shorter, the breakdown voltage gets higher. The distribution effect operates when the doping level of the deep P+ layer exceeds the appropriate value to prevent punch-through between the metal electrode and the N-drift region. This structure can be applied easily to various TIGBTs with simple processes addition.