Mix-mode forward-biased diode with low clamping voltage for robust ESD applications.

The forward-biased diode has been widely applied in electrostatic discharge (ESD) protection projects. In this Letter, various diodes with finger-shaped topology are studied by transmission line pulse (TLP) and emission microscope (EMMI) experiments. Among them, a novel mix-mode diode with P-well and floating deep N-well, called MMDIO, is fabricated by the same process and footprint, except that some discrete N+ regions are being added to the original anode P+ region. This approach forms a combination of a parasitic NPN transistor and a PNPN structure, which can significantly optimise the ESD current efficiency and clamping voltage (VCL). According to the comprehensive comparison, the MMDIO with overlapped anode N+ layout could endure the failure current 1.25 times higher than that of a regular diode under the same junction capacitance (Cj), while the VCL is reduced by 20%. Accordingly, the MMDIO is an attractive solution to pass the higher ESD level without any negative influence. [ABSTRACT FROM AUTHOR]