Browse Prior Art Database

Bipolarity Bipolar Device

IP.com Disclosure Number: IPCOM000049025D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Ayers, RL: AUTHOR

Abstract

Fig. 1 is a three-dimensional view of a cross-section of the bipolarity bipolar device showing its formation in an N-type epitaxial layer having P-type isolation regions 1 defining an N-type epitaxial island and an N type subcollector 3. A P-type base diffusion 12 having an L-shape is deposited in the N-type epitaxial region and an N-type emitter 10 is formed in the "foot" of the L-shaped base region. The length of the vertical stem of the L-shaped base is designed to form a desired resistance R1 between the emitter's position and the base contact at the top of the vertical stem of the L-shape. A P+ diffusion 5 is formed at the same time as is the base diffusion 12 and will serve as the source of a P channel FET device 7. shown also in the circuit schematic diagram of Fig. 2.

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Bipolarity Bipolar Device

Fig. 1 is a three-dimensional view of a cross-section of the bipolarity bipolar device showing its formation in an N-type epitaxial layer having P-type isolation regions 1 defining an N-type epitaxial island and an N type subcollector 3. A P- type base diffusion 12 having an L-shape is deposited in the N-type epitaxial region and an N-type emitter 10 is formed in the "foot" of the L-shaped base region. The length of the vertical stem of the L-shaped base is designed to form a desired resistance R1 between the emitter's position and the base contact at the top of the vertical stem of the L-shape. A P+ diffusion 5 is formed at the same time as is the base diffusion 12 and will serve as the source of a P channel FET device 7. shown also in the circuit schematic diagram of Fig. 2. An N-type collector contact 9 is formed for the N-type epitaxial layer 6 which will serve as the collector of the bipolar transistor 11, which is an NPN transistor (Fig. 2). A metal electrode 13 forms the base contact 2 and extends over the vertical portion of the L-shaped base and the horizontal or foot portion of the L-shaped base so as to overlap a thin oxide region 4 separating the terminal edge 15 of the base region 12 from the terminal edge of the P+ region 5, thereby forming a gate electrode for the P channel FET device 7. The circuit interconnections for the equivalent circuit are shown in Fig. 2.

The operation of the circuit is as follows. For a relatively positive potential applied to the base contact 2, the bipolar NPN device 11 operates in a conventional manner so that the emitter-collector path is conductive and current is drawn through the resistive load R17.

When the potentia...