Processing Method for Pyramid Shaped VMOSFET
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
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.