Polycrystalline silicon diode string for ESD protection of different power supply connections
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsKuo Reay Peng, Jian-Hsing Lee, Shui-Hung Chen
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Abstract
An ESD protection circuit protects integrated circuits having multiple power supply voltage sources from damage when an ESD event causes excessive differential voltages between the multiple separate power supply voltage sources. The ESD protection circuit has a string of serially connected lateral polycrystalline silicon diodes characterized by consistent turn-on threshold voltage level such that as the number of stage of the ESD protection circuit increase, the turn-on voltage threshold of the ESD protection circuit increase linearly.
Claims9
A method for forming an electrostatic discharge circuit comprising serially connected polycrystalline silicon diodes, said method comprising the steps of:
- providing a substrate;
- forming polycrystalline silicon members upon said substrate:
- doping a first portion of each of said polycrystalline silicon members with an impurity of a first type;
- doping a second portion of each of said polycrystalline silicon members with an impurity of a second type such that a junction is formed where the first portion of each of said polycrystalline silicon members adjoins said second portion of said polycrystalline members;
- connecting the second portion of one polycrystalline section to the first portion of a subsequent polycrystalline silicon member;
- connecting the first portion of a first polycrystalline silicon member to a first power supply voltage source;
- connecting the second portion of a last polycrystalline silicon member to a second power supply voltage source;
- and
- forming a resistor protection oxide member upon each of the polycrystalline silicon members to overlay said junction.
Dependencies are inferred from the claim text.