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Browse Prior Art Database

Processing Method for Pyramid Shaped VMOSFET

IP.com Disclosure Number: IPCOM000052181D
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 4 page(s) / 85K

Publishing Venue

IBM

Related People

Lechaton, JS: AUTHOR [+2]

Abstract

Methods of fabricating VMOSFETs are shown that have an obtuse channel t buried source angle. Figs. 1-5 show the processing procedure for a pyramid-shaped (PS)-VMOSFET with a pyramid-shaped buried source. Fabrication procedure for PS-VMOSFET is as follows: a) Epitaxially grow N+, N layers 14, 15, respectively, on silicon substrate 13, as shown in Fig. 1. The substrate is of <100> crystallographic orientation. b) First V-etch to form source pyramids in the epitaxial layers 14, 15, as shown in Fig. 2. The preferred chemical etch is ethylenediamine-pyrocatechol-water solution. c) Dopant in the N/+/ layer 14 is driven into the P- substrate 13 to produce the Fig. 3 structure. d) Epitaxially grow a P/Pi layer 16 to form the Fig. 4 structure.

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Processing Method for Pyramid Shaped VMOSFET

Methods of fabricating VMOSFETs are shown that have an obtuse channel t buried source angle. Figs. 1-5 show the processing procedure for a pyramid-shaped (PS)-VMOSFET with a pyramid-shaped buried source. Fabrication procedure for PS-VMOSFET is as follows: a) Epitaxially grow N+, N layers 14, 15, respectively, on silicon substrate 13, as shown in Fig. 1. The substrate is of <100> crystallographic orientation. b) First V-etch to form source pyramids in the epitaxial layers 14, 15, as shown in Fig. 2. The preferred chemical etch is ethylenediamine-pyrocatechol-water solution. c) Dopant in the N/+/ layer 14 is driven into the P- substrate 13 to produce the Fig. 3 structure. d) Epitaxially grow a P/Pi layer 16 to form the Fig. 4 structure.

e) A second V-etch plus other necessary steps are made to complete the device shown in Fig. 5 including the formation of surface N/+/ region 17, the gate dielectric layer 18, the surface dielectric layer 19, contact 20 to region 17, and gate electrode 21.

Figs. 6-11 show the processing method for a PS-VMOSFET with an octahedron-shaped buried source. The fabrication process for this embodiment of PS-VMOSFET includes: a) A first V-etch is made into the P-substrate 25 to form groove/ trench 26, as seen in Fig. 6. b) The trench/groove is epitaxially filled to produce the N+ region 27, as shown in Fig. 7, by selective silicon epitaxy or by etch back of the N/+/layer after epitaxy fill. c) Epitaxially grow an N layer 28 over the surface of substrate 25 having the Nregion 27 therein, as shown in Fig. 8. d) Etch the layer 28 to form the N pyramid, as shown in Fig. 9.

e) Epitaxi...