Browse Prior Art Database

ELECTROSTATIC DISCHARGE PROTECTION STRUCTURE

IP.com Disclosure Number: IPCOM000027299D
Original Publication Date: 1996-Feb-29
Included in the Prior Art Database: 2004-Apr-07
Document File: 4 page(s) / 131K

Publishing Venue

Xerox Disclosure Journal

Abstract

Electrostatic discharge (ESD) protection structures for semiconductor devices are fabricated so that once they fail, a protected semiconductor device is no longer operable. The failure mode is that of a short circuit whereby, the short circuit provides a direct connection between a voltage source and ground.

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XEROX DISCLOSURE JOURNAL

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ELECTROSTATIC DISCHARGE Proposed Classification PROTECTION STRUCTURE U.S. C1.361/212 David A. Drum
Sophie V. Vanderbroek
William G. Hawkins

Int. C1. HOlg 50/12

18 Input Pad

r

28

20

-

I- I FUSE

1 ---- -,,I

IC

7

Drain

XEROX DISCLOSURE JOURNAL - Vol. 21, No. 1 JanuaryEebruary 1996 81

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21

26 Source 24 I -

Protection

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ELECTROSTATIC DISCHARGE PROTECTION STRUCTURE (Cont'd)

Electrostatic discharge (ESD) protection structures for semiconductor devices are fabricated so that once they fail, a protected semiconductor device is no longer operable. The failure mode is that of a short circuit whereby, the short circuit provides a direct connection between a voltage source and ground.

Proposed is a fuse which is placed in series with the ESD protection structure. When the ESD protection structure fails, the fuse becomes an open circuit so as to renew semiconductor operation.

The accompanying Figure is a schematic representation illustrating the proposed ESD protection structure. Circuit 10 includes a semiconductor 28
which may be integrated circuit (IC) devices typically found in customer replaceable units (CRU's) on xerographic products. The application requires that semiconductor 28 be better protected from ESD energy than most other applications using very large scale integration (VLSI) circuits.

ESD energy presented to circuit 10 is simulated by Human Body Model (HBM)
12. HBM failure is a capacitor discharge failure which occurs when a person or conductive object discharges to or through a semiconductor device to ground. One skilled in the art will appreciate the fact that in HBM 12, a capacitor 14 is charged by ESD pulse 15 and discharged through a resistor 13. Capacitor 14
represents the human body capacitance. The exact value varies from one human to another, but is generally simulated with a value of approximately 150 picofarads. Resistor 13 is chosen to closely match the discharge time characteristics of a typical human body which is approximately 1500 ohms.

ESD protection structure 22 may be a 500 micron wide thick-field oxi...