ESD-Reliability Enhancement in a High-Voltage 60 V Square-Type PLDMOS by the Guard-Ring Engineering

For the high-voltage 60-V square type pLDMOS, a parasitic SCR np arrangement was added into the outer guardring zone and modulated the STI width to investigate the impact of the ESD protection immunity. There are five kinds of STI width such as 15 μm (reference group), 20 μm, 25 μm, 30 μm, and 35 μm. As a parasitic SCR (np type) modulated in the guard ring, Vt1 does not change significantly, and Vh tends to increase as the STI width becomes wider. The Vh parameter has a maximum value of 72.288V in the STI35 DUT. Meanwhile, the It2 values can be higher than the reference group 2.856A in the STI15, STI20, STI30 DUTs, especially as for the STI 30 μm DUT (ESD reliability capability It2 increased 36.6% compared with the reference group) and the Vh can exceed 60-V (no latch-up risk).