| 摘要 |
Integrated circuits having built-in electrostatic discharge protection thyristors include a semiconductor substrate with well regions of predetermined conductivity type therein which enable the formation of pairs of built-in thyristors which provided overvoltage protection. The substrate preferably contains first and second well regions of first and second conductivity type, respectively, at spaced locations, and third and fourth well regions of second and first conductivity type, respectively, which form respective P-N junctions with the first and second well regions. A first pair of guard regions of opposite conductivity type is also formed in the third well region, and this first pair of guard regions is electrically coupled to a first reference potential. In addition, a second pair of guard regions of opposite conductivity type is formed in the fourth well region and this pair of guard regions is electrically connected to a second reference potential. A semiconductor region of second conductivity type is also formed in the first well region and a semiconductor region of first conductivity type is formed in the second well region. Finally, a first guard ring of first conductivity type is formed in the first well region and a second guard ring of second conductivity type is formed in the second well region to complete the structures of a pair of thyristors. Here, the first guard ring is preferably electrically connected to the second reference potential and the second guard ring is electrically connected to the first reference potential. An input/output (I/O) pad is also electrically coupled to the semiconductor regions of first and second conductivity type, so that damage caused by excessive voltage can be inhibited upon latch-up of the built-in thyristors.
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