×

Bipolar ESD protection for integrated circuits

  • US 5,304,839 A
  • Filed: 03/06/1992
  • Issued: 04/19/1994
  • Est. Priority Date: 12/04/1990
  • Status: Expired due to Term
First Claim
Patent Images

1. An integrated circuit formed in a semiconductor body, and having a conductive bondpad that is coupled to at least one of input or output circuitry, wherein an electrostatic discharge (ESD) protection means is connected to said bondpad for conducting an electric charge from said bondpad to a negative (VSS) power supply conductor on said integrated circuit when the positive voltage on said bondpad exceeds a given limit,characterized in that said electrostatic discharge protection means comprises a pnp bipolar transistor having:

  • an n-type base region located in an n-type tub region that is located in a p-type substrate;

    a heavily doped p-type emitter region formed directly in said n-type tub and connected to said bondpad through a conductor formed in a window in an overlying dielectric;

    and a p-type collector region that is connected to said negative power supply conductor;

    wherein said pnp bipolar transistor has its collector formed in a p-type tub region located adjacent to said n-type tub region in said semiconductor body;

    wherein said base is connected to said bondpad by means comprising a heavily doped n-type contact region formed in said n-type tub region;

    whereby a delay means is formed comprising a resistance in said n-type tub between said contact region and said emitter, and also comprising a capacitance between said n-type tub and said p-type substrate;

    and whereby said bipolar transistor become highly conducting during a positive voltage ESD event, and becomes significantly less conducting when normal operating voltages are applied to said bondpad.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×