The Aalysis of Ruggedness on 450V LDMOSFET

• Main Authors: Chung-Yeh Wu, 巫宗曄
• Other Authors: J. Gong
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/83096491000896392015

碩士 === 國立清華大學 === 電子工程研究所 === 93 === In this thesis, we use TCAD simulation software to design a 450V LDMOSFET. We adjust the parameters to make the device have not only low turn-on resistance but also high breakdown voltages. Through analyzing the device’s currents’ distribution after it has broken down, we can find out that the breakdown occurs at drain edge. Most of the currents gather at the junction beneath the source contact and then flow out the source. To make the device more “rugged”, it is important to disperse the device’s breakdown currents as uniform as possible. We add an n-type adaptive layer under drain region to improve the currents’ distribution. Without n-type adaptive layer, most of the device’s currents gather at the junction beneath the source contact. The position where breakdown occurs is shifted from drain edge to channel edge. Thus part of the currents flow through the channel edge then out of the source. And the currents are more dispersed. Adjusting the currents flowing through the junction beneath the source region and the channel edge, when the currents flow through the two regions are almost equal, the currents’ distribution will be most uniform. And we can get the most “rugged” devices.