Method for four direction low capacitance ESD protection
First Claim
1. A low capacitance device structure with associated parasitic bipolar transistor on a substrate for the purpose of providing four-way electrostatic voltage discharge protection to a plurality of active semiconductor devices connected to an I/O logic circuit line and including ESD protection of a power bus system comprising:
- isolation elements defining an active circuit area;
a first and second FET gate element upon said substrate surface;
a plurality of first, second and third doped regions of opposite dopant than said substrate, wherein said plurality of first doped regions form a source element and a drain element for said first FET gate element forming a first NFET device and said plurality of second doped regions form a source region and a drain region for said second FET gate element forming a second NFET device;
a plurality of fourth and fifth doped regions within said substrate of similar dopant as said substrate;
an electrical connection system for said first, second, third, fourth and fifth doped regions;
a surface passivation layer for said ESD protection device.
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Abstract
The invention describes a structure and a process for providing ESD semiconductor protection with reduced input capacitance. The structure consists of heavily doped P+ guard rings surrounding the I/O ESD protection device and the Vcc to Bss protection device. In addition, there is a heavily doped N+ guard ring surrounding the I/O protection device its P+ guard ring. The guard rings enhance structure diode elements providing enhanced ESD energy discharge path capability enabling the elimination of a specific conventional Vss to I/O pad ESD protection device. This reduces the capacitance seen by the I/O circuit while still providing adequate ESD protection for the active circuit devices.
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Citations
12 Claims
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1. A low capacitance device structure with associated parasitic bipolar transistor on a substrate for the purpose of providing four-way electrostatic voltage discharge protection to a plurality of active semiconductor devices connected to an I/O logic circuit line and including ESD protection of a power bus system comprising:
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isolation elements defining an active circuit area; a first and second FET gate element upon said substrate surface; a plurality of first, second and third doped regions of opposite dopant than said substrate, wherein said plurality of first doped regions form a source element and a drain element for said first FET gate element forming a first NFET device and said plurality of second doped regions form a source region and a drain region for said second FET gate element forming a second NFET device; a plurality of fourth and fifth doped regions within said substrate of similar dopant as said substrate; an electrical connection system for said first, second, third, fourth and fifth doped regions; a surface passivation layer for said ESD protection device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification