Method of fabrication of MOSFET device with buried bit line
First Claim
1. A method of fabrication of a DRAM MOSFET comprisinga) forming a FOX structure on the surface of a semiconductor substrate, and applying field oxidation,b) implanting a buried bit line into said substrate,c) forming a gate oxide onto said substrate,d) applying polysilicon and etching with a mask,e) forming source/drain regions in said substrate,f) forming a doped contact PLUG beneath a first one of said source/drain regions in said substrate said PLUG providing connection between said one source/drain region and said buried bit line, andg) forming a polysilicon structure connected to a second one of said source/drain regions in said substrate, andh) forming a polysilicon/ONO/polysilicon capacitor.
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Accused Products
Abstract
A doped FET DRAM includes a silicon substrate, with a buried bit line in the silicon substrate. A plug extends down through the substrate to the bit line. A source region and a drain region are positioned above the plug in the substrate with one thereof connected to the plug with a layer of gate oxide above the source region and drain region. A gate above the gate oxide is juxtaposed with the source region and drain region. The source is connected to a capacitor formed of two layers of polysilicon separated by a dielectric of an ONO oxide layer.
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Citations
14 Claims
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1. A method of fabrication of a DRAM MOSFET comprising
a) forming a FOX structure on the surface of a semiconductor substrate, and applying field oxidation, b) implanting a buried bit line into said substrate, c) forming a gate oxide onto said substrate, d) applying polysilicon and etching with a mask, e) forming source/drain regions in said substrate, f) forming a doped contact PLUG beneath a first one of said source/drain regions in said substrate said PLUG providing connection between said one source/drain region and said buried bit line, and g) forming a polysilicon structure connected to a second one of said source/drain regions in said substrate, and h) forming a polysilicon/ONO/polysilicon capacitor.
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8. A method of fabrication of a DRAM MOSFET on a semiconductor substrate, said method comprising
a) implanting a buried bit line into said semiconductor substrate, b) forming an epitaxial layer above said buried bit line, c) forming a FOX structure on the surface of said semiconductor substrate, and performing a field oxidation step, d) forming a gate oxide onto said substrate, e) applying polysilicon and etching with a mask, f) forming source/drain regions in said substrate, g) forming a doped contact PLUG beneath a first one of said source/drain regions in said substrate, said PLUG providing connection between said one source/drain region and said buried bit line, h) forming a polysilicon structure connected to a a second one of said source/drain regions on said substrate, and i) forming a polysilicon/ONO/polysilicon capacitor.
Specification