ESD Design and Analysis by Drain Electrode-Embedded Horizontal Schottky Elements for HV nLDMOSs

• Main Authors: Shi-Zhe Hong, Shen-Li Chen
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Electronics
• Subjects: electrostatic discharge (ESD); holding voltage (V_h); lateral diffusion MOS (LDMOS); schottky diode; secondary breakdown current (I_t2); transmission-line pulse system (TLP system)
• Online Access: https://www.mdpi.com/2079-9292/10/2/178

Electrostatic discharge (ESD) events can severely damage miniature components. Therefore, ESD protection is critical in integrated circuits. In this study, drain-electrode-embedded horizontal Schottky diode contact modulation and Schottky length reduction modulation were performed on a high-voltage 60-V n-channel laterally diffused metal-oxide–semiconductor transistor (nLDMOS) element. The effect of the on-voltage characteristics of cascade Schottky diodes on ESD protection was investigated. By using a transmission-line pulse tester, the trigger voltage, holding voltage, and secondary breakdown current (I_t2) of the nLDMOS element were determined using the I–V characteristic. As the N⁺ area was gradually replaced by the parasitic Schottky area at the drain electrode, an equivalent circuit of series Schottky diodes formed, which increased the on-resistance. The larger the Schottky area was the higher the I_t2 value was. This characteristic can considerably improve the ESD immunity of nLDMOS components (highest improvement of 104%). This is a good strategy for improving ESD reliability without increasing the production steps and fabrication cost.