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Browse Prior Art Database

Overvoltage Protection in Integrated Circuits

IP.com Disclosure Number: IPCOM000076079D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Hubacher, EM: AUTHOR [+2]

Abstract

In integrated circuits, particularly in high-density integrated circuits, the power supplies for such circuits utilized in computers must be held to very close tolerances. The present structure provides means for readily obtaining overvoltage protection on integrated circuits.

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Overvoltage Protection in Integrated Circuits

In integrated circuits, particularly in high-density integrated circuits, the power supplies for such circuits utilized in computers must be held to very close tolerances. The present structure provides means for readily obtaining overvoltage protection on integrated circuits.

The concept is illustrated with respect to a standard integrated circuit involving isolated pockets 10 in N epitaxial layer 11, enclosed by a combination of P isolation diffusions 12 and P substrate 13. The particular device enclosed within the pocket shown is a transistor T comprising emitter region 14, base region 15, and N+ subcollector 16. Simultaneously with the formation of the subcollector 16, an additional N+ region 17 is diffused, as shown, along the boundary of p regions 12 and epitaxial layer 11. This provides the junction of the epitaxial region 11 with P isolation region 12, with a junction breakdown voltage of about six volts.

Since the N epitaxial region 11 in integrated circuits of the type shown is normally connected to the most positive voltage supply, +V, and the P isolation is connected to the most negative supply, -V, the new junction serves as a clamp and protects the more sensitive junctions in the circuit, i.e., collector/base and collector/isolation junctions, from power supply overvoltage spikes. For example, since the breakdown voltage of the structure shown is about six volts, circuits operating with power supply requ...