Memory elements and methods for making same
View Patent ↗Annular, linear, and point contact structures are described which exhibit a greatly reduced susceptibility to process deviations caused by lithographic and deposition variations than does a conventional circular contact plug. In one embodiment, a standard conductive material such as carbon or titanium nitride is used to form the contact. In an alternative embodiment, a memory material itself is used to form the contact. These contact structures may be made by various processes, including chemical mechanical planarization and facet etching.
1. A memory cell comprising:
a substrate;
a structure protruding from the substrate, the structure having at least one corner, the structure comprising one of a first conductive material and a first memory material;
a layer of insulating material disposed over the structure in a manner that leaves the at least one corner of the structure exposed to form at least one point contact;
at least one layer of material disposed over the at least one point contact, the at least one layer of material comprising a second conductive material if the structure comprises the first memory material, and the at least one layer of material comprising a second memory material if the structure comprises the first conductive material; and
a conductive layer disposed over the at least one layer of material if the at least one layer of material comprises the second memory material.
2. The memory cell of claim 1 , wherein the substrate comprises a semiconductor substrate.
3. The memory cell of claim 1 , wherein the first and second memory materials comprise a chalcogenide material.
4. The memory cell of claim 1 , wherein the substrate comprises a conductive region in electrical contact with the structure.
5. The memory cell of claim 1 , wherein the structure comprises a pillar.
6. The memory cell of claim 5 , wherein the pillar is substantially square and comprises four corners.
7. The memory cell of claim 5 , wherein the pillar contact is substantially rectangular and comprises four corners.