ESD-Performance Enhancement of Circular Ultra-High-Voltage 300-V N-Channel Lateral-Diffused MOSFETs by Source/Drain Embedded Schottky Diodes

Abstract

This study with the area-efficient design for improving electrostatic discharge (ESD) and Latch-up (LU) abilities in the ultra-high voltage (UHV) n-channel Lateral-Diffused MOSFET (nLDMOS) is investigated via a TSMC 0.5- $\mu \text{m}$ UHV Bipolar CMOS DMOS (BCD) process. There are two architectures of these nLDMOS devices with embedded Schottky diodes in the electrode area. Firstly, the drain side is divided into three concentric circles and embedded with Schottky diodes. The influence of these samples with different layout arrangements on ESD is evaluated. For the second item, UHV nLDMOS devices with the source side embedded Schottky diodes by two alternative layout types are developed. Experimental results showed that an UHV nLDMOS with embedded Schottky diodes at the drain side can significantly improve ESD ability, especially for the fully embedded Schottky diodes at the drain side (being with the highest figure of merit (FOM) value in the ESD, LU, and cell-area considerations). On the other hand, with embedded Schottky diodes at the source side can increase the holding voltage which can effectively improve the LU immunity.