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Ion Implanted Base Region Formed After the Emitter for Bipolar Transistors

IP.com Disclosure Number: IPCOM000089239D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Barile, CA: AUTHOR [+3]

Abstract

This is a process in which an ion-implanted boron base region is formed after the emitter. By this method the requirement for tailoring the emitter is eliminated, and the beta and other parameters of the transistor may be selected by adjusting the base implant energy.

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Ion Implanted Base Region Formed After the Emitter for Bipolar Transistors

This is a process in which an ion-implanted boron base region is formed after the emitter. By this method the requirement for tailoring the emitter is eliminated, and the beta and other parameters of the transistor may be selected by adjusting the base implant energy.

The cross-section of the vertical structure shown in Fig. 1 represents the base and emitter area defined by recessed isolation. Standard processing is used, including a composite silicon dioxide/silicon nitride mask 4/6 to define the N-type and P-type contact regions 10 and 12, respectively.

In Fig. 2 photoresist layer 5 is used to protect all areas except the emitters for the subsequent implantation of emitter 7.

After layer 5 is stripped away, the emitter is driven-in as shown in Fig. 3.

A reoxidation then is conducted at a suitable temperature to regrow silicon dioxide 8 over N+ region 7. Oxidation also occurs over the region 12 but at a slower rate. The resulting structure in Fig. 4 is planar. A boron base 9 is then implanted using two energies. The deep, high-energy implant controls beta and internal base resistance depending on the base width. The shallow, low-energy implant controls the BV(ebo) characteristic and base sheet resistance.

A low temperature anneal activates the implanted base, after which a dip etch is used to open both N and P contact areas.

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