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Polysilicon Resistor Fabrication Technique for Bipolar Integrated Circuits

IP.com Disclosure Number: IPCOM000051099D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Lee, CH: AUTHOR

Abstract

Described is a poly-Si resistor fabrication technique which is compatible with standard bipolar manufacturing technology. This process provides poly-Si resistors of low temperature and voltage coefficients as well as high resistor values for low standby power circuits, resulting in performance improvement. The proposed dopants for this process are P and As for the resistor and the resistor contact doping, respectively. Group V elements have been popularly used for collector contact and emitter doping in bipolar transistor structures. N type doping of high concentration was found effective to prevent resistor degradation during metallization. The process is outlined with reference to the drawings.

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Polysilicon Resistor Fabrication Technique for Bipolar Integrated Circuits

Described is a poly-Si resistor fabrication technique which is compatible with standard bipolar manufacturing technology. This process provides poly-Si resistors of low temperature and voltage coefficients as well as high resistor values for low standby power circuits, resulting in performance improvement. The proposed dopants for this process are P and As for the resistor and the resistor contact doping, respectively. Group V elements have been popularly used for collector contact and emitter doping in bipolar transistor structures. N type doping of high concentration was found effective to prevent resistor degradation during metallization. The process is outlined with reference to the drawings.

As shown in Fig. 1, in the course of bipolar circuit fabrication, a vertical structure consists of the recessed oxide isolation (ROI) 1, base 2 and base oxide 3 on which a poly-Si film 4 of about 400 nm is deposited after completion of base reoxidation. A thin (pyrolytic) SiO(2) layer 5 is subsequently deposited. Phosphorus is implanted into the poly-Si film 4, as identified in region 6 of Fig. 1, for resistor doping.

In Fig. 2, the poly-Si resistor is then defined by means of a photolithographic process and reactive ion etching (RIE). A Si(3)N(4) film 7 is deposited. In standard bipolar device process steps, the all contact" photolithography, RIE Si(3)N(4), photoresist (P/R) Btrip, emitter P/R (I...