DRAM cell utilizing novel capacitor
First Claim
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1. A dynamic RAM cell comprising:
- an MOS transfer transistor formed in a semiconductor substrate and having a source region, a drain region, a channel region, and an insulated gate, said transfer transistor being used for selectively writing data into and reading data out of said RAM cells;
a storage capacitor comprising;
a first electrode formed of a first conductive layer, said first electrode being of a granular material and being electrically connected to said source region;
a second conductive electrode overlying said first electrode; and
a storage dielectric insulating layer located between said first and second electrodes;
a bit line connected to said drain; and
a word line connected to said insulated gate,wherein said first electrode is formed to have an irregular surface formed along the surfaces of the grain boundaries of said first electrode and said storage dielectric and said second conductive electrode substantially follows the contours of said first electrode, thereby increasing the capacitance of said storage capacitor.
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Abstract
A dynamic RAM is provided with enhanced charge storage capacity by increasing the surface area between the two electrodes of the storage capacitor. The first electrode consists of a thick conductive layer whose vertical sidewalls provide the extra surface area for charge storage. The second electrode is used to partially planarize the surface topology. The first electrode can also be used as the gate of a sensing transistor in a signal amplifying cell, as well as in multiport and multistate dynamic RAM cells.
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8 Claims
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1. A dynamic RAM cell comprising:
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an MOS transfer transistor formed in a semiconductor substrate and having a source region, a drain region, a channel region, and an insulated gate, said transfer transistor being used for selectively writing data into and reading data out of said RAM cells; a storage capacitor comprising; a first electrode formed of a first conductive layer, said first electrode being of a granular material and being electrically connected to said source region; a second conductive electrode overlying said first electrode; and a storage dielectric insulating layer located between said first and second electrodes; a bit line connected to said drain; and a word line connected to said insulated gate, wherein said first electrode is formed to have an irregular surface formed along the surfaces of the grain boundaries of said first electrode and said storage dielectric and said second conductive electrode substantially follows the contours of said first electrode, thereby increasing the capacitance of said storage capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification