Patent ID: 6537868
Filing Date: 2003-03-25
Classification: H01L

Abstract:
A method for forming a cascaded diode providing ESD protection to portions of integrated circuits with reduced substrate leakage current, said cascaded diode being a chain of coupled elemental diodes, comprising:fabricating elemental diodes by forming for each diode, an n-well in a p-substrate, a p region and an n region in the n-well, and forming a deep n-well disposed under and connected to the n-well, so that the bi-polar PNP current gain is less than one; connecting electrically the p region of a first elemental diode to a pin or pad at the higher potential side of said portion of an integrated circuit to be protected and the n region of said first elemental region to the p region of the following intermediate elemental diode; connecting electrically the p region of an intermediate diode to the n region of the preceding elemental diode and said n region of an intermediate elemental diode to the p region of the following elemental diode; connecting electrically the p region a last elemental diode to the n region of the preceding elemental diode and its said n region to the other end of said portion of an integrated circuit.