Browse Prior Art Database

Pedestal Base (NPN) and PNP

IP.com Disclosure Number: IPCOM000075680D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Antipov, I: AUTHOR [+2]

Abstract

The integrated circuit structure with complementary transistors shown in Fig. A, is manufactured by the following process. Figs. B through F show the stages of manufacture of the PNP device. The NPN and PNP devices are made simultaneously. 1) Starting with P- substrates (other type could be used) 2) Initial oxidation 3) Photoresist - open subcollector area 4) Diffusion - "N+" - 10/21/ (Fig. B) - reoxidation 5) Photoresist - open isolation, base area under emitter 6) Diffusion "P+" - 10/20/ (Fig. C) - reoxidation 7) Strip oxide 8) Epitaxy - "N-" - 2.0u thick (Fig. D) 9) Post epitaxial oxidation 10) Photoresist - open resistor, collector contact area 11) Diffusion - "N" - 10/19/ (Fig. E) - reoxidation 12) Photoresist - open isolation base contact area 13) Diffusion - "P" - 10/19/ (Fig.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 87% of the total text.

Page 1 of 2

Pedestal Base (NPN) and PNP

The integrated circuit structure with complementary transistors shown in Fig. A, is manufactured by the following process. Figs. B through F show the stages of manufacture of the PNP device. The NPN and PNP devices are made simultaneously. 1) Starting with P- substrates (other type could be used) 2) Initial oxidation 3) Photoresist - open subcollector area 4) Diffusion - "N+" - 10/21/ (Fig.
B) - reoxidation 5) Photoresist - open isolation, base area under emitter 6) Diffusion "P+" - 10/20/ (Fig. C) - reoxidation 7) Strip oxide 8) Epitaxy - "N-" - 2.0u thick (Fig. D) 9) Post epitaxial oxidation 10) Photoresist - open resistor, collector contact area 11) Diffusion - "N" - 10/19/ (Fig. E) - reoxidation 12) Photoresist - open isolation base contact area 13) Diffusion - "P" - 10/19/ (Fig. F) - reoxidation
14) Pyrolytic oxide or silicon nitride 15) Photoresist - open emitter, collector contact area 16) Diffusion - "N+" - 10/21/.

Diffusion of the P+ impurity into the base area under the emitter during first isolation diffusion (step 6), as proposed here, increases P impurity concentration near the collector junction in this region. This allows making narrower base transistors for the same punch through voltage, as compared to the regular single-base diffusion transistors. This leads to superior transistor cutoff frequency (ft) and current-gain (B) characteristics of pedestal base transistors.

Depending upon the need in the NPN device, trade o...