Semiconductor device manufacturing: process – Making passive device – Trench capacitor
Reexamination Certificate
1998-06-30
2001-11-20
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Making passive device
Trench capacitor
C438S239000, C438S243000, C438S249000, C438S392000
Reexamination Certificate
active
06319787
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to trench capacitors and more particularly to trench capacitors adapted for use with Dynamic Random Access Memories (DRAMs).
As is known in the art, a challenge in current DRAM technology is to provide smaller and smaller feature sizes to thereby increase the number of storage cells in a given surface space of a chip and yet provide such storage cell with a capacitor of sufficient size to store, and maintain, a requisite amount of charge. One approach currently being investigated is to use dielectric materials for the capacitor having high dielectric constants. Other approaches seek to enhance the total surface area of the capacitor structure by modifying the geometrical layout of the storage cell.
SUMMARY OF THE INVENTION
In accordance with the invention, a method is provided for forming a trench capacitor. The method includes providing a substrate with a trench extending into the substrate. One conductive region is formed nested within a second conductive region, both conductive regions being disposed within the trench. Portions of a dielectric material are disposed between the conductive regions to dielectrically separate one of the conductive regions from another one of the conductive regions. The dielectrically separated conductive regions provide a pair of electrodes for the capacitor.
With such method, because the conductive regions used to provide the electrodes of the capacitor are nested one within the other, a trench capacitor is provided having increased capacitance within a substantially constant surface area of the substrate.
In accordance with another feature of the invention, the method includes the step forming the plurality of conductive regions as concentric conductive regions.
In accordance with another feature of the invention, the substrate is provided with a conductive region therein. One of the concentric conductive regions providing one of the electrodes for the capacitor is electrically connected to the conductive region through a bottom portion of the trench.
In accordance with another feature of the invention, the electrically connecting step includes the step of out-diffusing dopant in an electrically conductive region formed in the trench to the conductive region in the substrate.
In accordance with another feature of the invention, a method for forming a trench capacitor is provided. A trench is formed in a substrate. A sacrificial material is deposited over sidewalls of the trench. A conductive material is deposited over the sacrificial material to provide an electrode for the capacitor. The sacrificial material is removed exposing peripheral portions of the conductive material and sidewall portions of the trench with the removed sacrificial material forming an open region disposed between the sidewalls and the exposed peripheral portions of the conductive material. A dielectric material is applied to the exposed peripheral portions of the conductive material and to the sidewall portions of the trench to line such open region with such dielectric material. A conductive material is introduced into the dielectric lined open region to provide another electrode for the capacitor.
In accordance with another feature of the invention, a trench capacitor is provided having a substrate with a trench therein. A dielectric material is disposed on sidewalls of the trench. A first conductive material having a hollow region therein is provided, such first conductive material having outer peripheral portions disposed on the first dielectric material and providing a first electrode for the capacitor. A second dielectric material having a hollow region therein is provided, such second dielectric material being disposed on inner peripheral portions of the first conductive material. A second conductive material is disposed within the hollow region in the second dielectric material to provide a first electrode for the capacitor.
In accordance with another feature of the invention, the substrate has a conductive region therein and the first electrode is in electrical contact with the conductive region.
In accordance with still another feature of the invention, a substrate is provided having a doped region. A trench is formed in the substrate. Sidewalls of the trench are covered with a dielectric material. A conductive material is formed in the trench over the dielectric material with a portion of the conductive material being in contact with the doped region of the substrate.
In accordance with another feature of the invention, a trench capacitor is provided having a substrate with a trench therein. A conductive material is disposed within the trench to provide a first electrode of the capacitor. A first dielectric material is disposed on sidewalls of the conductive material. A conductive material is disposed on the first dielectric material to provide a second electrode for the capacitor. A second dielectric material is disposed between the conductive material providing the second electrode and sidewalls of the trench.
In accordance with another feature of the invention, one of the concentric conductive regions providing one of the electrodes for the capacitor is electrically connected to the conductive region through a bottom portion of the trench.
In accordance with another feature of the invention, a trench capacitor is provided having a substrate with a trench extending therein. A plurality of nested conductive regions is disposed within the trench. A dielectric material is disposed within the substrate. The dielectric material has portions thereof disposed between the nested conductive regions to dielectrically electrically separate one of the conductive regions from another one of the conductive regions. The dielectrically separated conductive regions provide a pair of electrode for the capacitor.
In accordance with another feature of the invention, selected ones of the nested conductive regions are concentric.
In accordance with another feature of the invention, the substrate has a conductive region therein and one of the concentric conductive regions providing one of the electrodes is electrically connected to the conductive region in the substrate.
In accordance with another feature of the invention, selected ones of the concentric conductive regions are electrically connected to provide one of the electrodes for the capacitor and the electrically connected concentric regions are electrically connected to the conductive region in the substrate.
REFERENCES:
patent: 5244824 (1993-09-01), Sivan
patent: 5595926 (1997-01-01), Tseng
patent: 5677225 (1997-10-01), Park
patent: 6022786 (2000-02-01), Franosch et al.
patent: 6077739 (2000-06-01), Chang
Enders Gerhard
Ilg Matthias
Widmann Dietrich
Braden Stanton C.
Lytle Craig P.
Siemens Aktiengesellschaft
Smith Matthew
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