Method for forming composite trench-fin capacitors for DRAMS
AssigneeLSI Logic Corporation
InventorMichael D. Rostoker
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Abstract
A semiconductor memory device capacitor is disclosed which has a trench capacitor portion provided in a semiconductor substrate and a fin capacitor portion provided above the substrate. The trench capacitor portion includes (i) a trench extending from an upper surface of the semiconductor substrate downwardly into the substrate, and (ii) an electrically conductive trench electrode provided interior to the trench. And the fin capacitor portion includes (i) a fin electrode having a body portion and two or more electrically conductive fins extending outwardly from the body portion, (ii) a fin dielectric layer conformally coating the two or more electrically conductive fins, and (iii) a cell electrode surrounding and in intimate contact with the two or more electrically conductive fins.
Claims4
A method of forming a memory cell on a semiconductor subtrate having an upper surface, the method comprising the following steps:
- forming a transistor, including (i) a gate on said upper surface of the semiconductor substrate, (ii) a source region in said semiconductor substrate, and (iii) a drain region in said semiconductor substrate;
- forming a passivation layer over said transistor;
- depositing alternating layers of a sacrificial material and a conductive electrode material;
- etching a trench through said alternating layers and said passivation layer and into said substrate, such that said trench contacts the source region;
- conformally depositing a top layer of said conductive electrode material in said trench and over a top layer of said sacrificial material located outside of the said trench;
- selectively etching to define fin edges of a cell capacitor;
- etching away said layers of said of sacrificial material to expose fins of composite trench-fin capacitor;
- forming a layer of dielectric material on exposed regions of said conductive electrode material;
- and
- forming a second electrode surrounding said fins.
Dependencies are inferred from the claim text.