Electrostatic discharge protection circuit
AssigneeTexas Instruments Incorporated
InventorRobert N. Rountre
Life of this patent
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Abstract
An ESD protection device includes a PNPN type device disposed between the input pad (12) and ground. A first P-layer (48) is disposed in an N-type well (46) which is formed in a P-type layer (44). A second N-region (52) is provided for connection to ground. This provides an SCR which can be turned on by avalanching the intermediate PN junction (32) to place the device in a regenerative mode for positive transients. For negative transients, a P+ region (54) is provided in P-layer (44) to bypass a PN junction (34) and a N+ region (50) is defined in the N-type region (46) to bypass PN junction (30). This provides a forward-biased diode for the negative transient.
Claims9
An electrostatic discharge protection device formed at a face of a semiconductor body, for conducting electrostatic discharge current from a terminal to a reference potential, comprising:
- a first region of semiconductor material of a first conductivity type formed at said face of said semiconductor body, and in conductive interface with said terminal;
- a second region of semiconductor material of a second conductivity type within which said first region is disposed;
- a third region of semiconductor material of the first conductivity type disposed adjacent said second region;
- a fourth region of semiconductor material of the second conductivity type disposed within said third region, said fourth region formed at said face of said semiconductor body, and in conductive interface with said reference potential;
- and
- a first ohmic connection between said terminal and said second region;
- wherein, responsive to a voltage applied to said terminal of a polarity relative to said reference potential so as to forward bias the junction between said first and second regions, and of sufficient magnitude to break down the junction between said second and third regions, current is conducted between said terminal and said reference potential substantially in a direction parallel to said face through said third region.
Dependencies are inferred from the claim text.