Abstract A method, and resultant structure, is described for fabricating a DRAM trench capacitor with a single pillar recessed below the level of the top surface of the silicon substrate in which it is formed. First and second insulating layers are formed over the silicon substrate, and patterned to form an opening to the silicon substrate. A portion of the silicon substrate is removed in the region defined by the opening, whereby a first trench is formed. Sidewall spacers are formed along the sides of the first trench from a third insulating layer. A first pillar is formed after depositing a first conductive layer between the sidewall spacers and over the trench and removing the first conductive layer except within the first trench. The sidewall spacers are removed. A portion of the silicon substrate in the first trench is removed that is not vertically masked by the pillar, and simultaneously a portion top of the pillar is removed, whereby a second trench and second pillar are formed at a greater depth in the silicon substrate. The remainder of the second insulating layer is also removed. A capacitor dielectric is formed in the second trench over the second pillar. A second conducting layer is formed over the dielectric layer and removed in the region outside of the trench to form the top capacitor electrode.
A capacitor with a single pillar recessed in a trench, comprising: a trench formed in a monocrystalline silicon substrate, wherein said substrate forms a first plate of said capacitor; a pillar formed in the center of, and extending up from the bottom of, said trench, comprising an upper portion of polycrystalline silicon and a lower portion of monocrystalline silicon in contact with said upper portion of polycrystalline silicon; a capacitor dielectric formed on the surface of said pillar and said trench; a second capacitor plate on said capacitor dielectric and within said trench.
Claim 2
Dependent Claim
93 words
A capacitor with a single pillar recessed in a trench, comprising: a trench formed in a monocrystalline silicon substrate, wherein said substrate forms a first plate of said capacitor; a pillar formed in the center of, and extending up from the bottom of, said trench, comprising an upper portion of polycrystalline silicon and a lower portion of monocrystalline silicon in contact with said upper portion of polycrystalline silicon; a capacitor dielectric formed on the surface of said pillar and said trench; a second capacitor plate on said capacitor dielectric and within said trench.
Claim 3
Dependent Claim
18 words
The capacitor of claim 1 wherein said trench has a width of between about 0.6 and 1.0 micrometers.
Claim 4
Dependent Claim
18 words
The capacitor of claim 1 wherein said trench has a depth of between about 8000 and 16,000 Angstroms.
Claim 5
Dependent Claim
18 words
The capacitor of claim 1 wherein said pillar has a height of between about 6000 and 12,000 Angstroms.
Claim 6
Dependent Claim
22 words
The capacitor of claim 1 wherein said capacitor dielectric is formed of a composite of silicon oxide, silicon nitride and silicon oxide.
Claim 7
Dependent Claim
15 words
The capacitor of claim 1 wherein said capacitor plate is formed of doped polycrystalline silicon.