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Exclusive OR or Bilevel Detecting Structure

IP.com Disclosure Number: IPCOM000051736D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

El-Kareh, B: AUTHOR

Abstract

A single isolated pocket is used to form, e.g., an exclusive OR structure or a bilevel circuit.

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Exclusive OR or Bilevel Detecting Structure

A single isolated pocket is used to form, e.g., an exclusive OR structure or a bilevel circuit.

As indicated in Fig. 1, a P type pocket 10 acting as a common base is formed in an N epitaxial layer 12 acting as a common collector disposed over a P- semiconductor substrate 14 with a junction 16 and an N+ subcollector 18 located between the substrate 14 and the N epitaxial layer 12. First and second emitters 20 and 22 are formed as N+ regions in P type pocket 10, defining a first transistor 32 and a second transistor 34, respectively. An N+ region 24 provided in N epitaxial layer 12 forms an interconnection with a first contact 26 for epitaxial layer or common collector 12. Second and third contacts 28 and 30 are disposed over the first and second emitters 20 and 22, respectively. Fig. 1 is a sectional view of a circuit which is shown schematically in Fig. 2 where the same reference numerals refer to similar elements in Fig. 1.

In the operation of the structure, with a voltage of, e.g. +4 volts on collector 12 and both emitter voltages either at +5 volts or at ground, both transistors 32 and 34 are off. If a voltage of +5 volts is applied to emitter 20 and emitter 22 is grounded, transistor 34 is turned on and transistor 32 is off. With a voltage of +5 volts at emitter 22 and emitter 20 grounded, transistor 32 is turned on and transistor 34 is off.

The peak of the base profile is chosen such that the predominant reverse current mechanism is tunneling. The tunneling current density is given by ## where N(A) is the peak base concentration, Eg is the energy gap and is equal to 1.08 eV, mu A is microamperes, and V(R) is the reverse voltage on the emitter-base junction of transistor 32. For a peak concentration N(A) approx. equal...