Multiple data state memory cell
View Patent ↗A programmable multiple data state memory cell including a first electrode layer formed from a first conductive material, a second electrode layer formed from a second conductive material, and a first layer of a metal-doped chalcogenide material disposed between the first and second electrode layers. The first layer providing a medium in which a conductive growth can be formed to electrically couple together the first and second electrode layers. The memory cell further includes a third electrode layer formed from a third conductive material, and a second layer of a metal-doped chalcogenide material disposed between the second and third electrode layers, the second layer providing a medium in which a conductive growth can be formed to electrically couple together the second and third electrode layers.
1. A multiple-state memory cell, comprising:
a first electrode coupled to a first voltage line;
a second electrode coupled to a second voltage line;
a multiple layer data state stack in which multiple data states are stored, the data-state stack including:
a first portion of a metal-doped chalcogenide material adjoining the first electrode and being located between the first and second electrodes, the first portion having a first thickness;
a third electrode of a conductive material adjoining the first portion; and
a second portion of a metal-doped chalcogenide material adjoining the third electrode, the second portion having a second thickness,
a fourth electrode of a conductive material adjoining the second portion; and
a third portion of a metal-doped chalcogenide material adjoining the fourth electrode, the third portion having a third thickness, wherein application of a programming voltage to the first electrode induces a resistance change within at least one of the first, second and third portions.
2. The memory cell of claim 1 wherein the first voltage line is a positive voltage line relative to the second voltage line.
3. The memory cell of claim 1 wherein the first voltage line is a negative voltage line relative to the second voltage line.
4. The memory cell of claim 1 wherein the first portion is positioned below the third electrode, and the third electrode is positioned below the second portion.
5. The memory cell of claim 4 wherein the third portion is positioned below the second electrode, and the fourth electrode is positioned below the third portion.
6. The memory cell of claim 1 wherein the first portion is positioned laterally adjacent to the third electrode, and the third electrode is positioned laterally adjacent to the second portion.
7. The memory cell of claim 6 wherein the third portion is positioned laterally adjacent to the fourth electrode, and the second electrode is positioned laterally adjacent to the third portion.
8. The memory cell of claim 1 wherein the first thickness is less than the second thickness.
9. The memory cell of claim 8 , wherein the third thickness is greater than the second thickness.
10. The memory cell of claim 1 wherein under the application of the programming voltage, the a change of the resistance of the first portion electrically couples the third electrode to the first electrode prior to a change of the resistance of the second portion electrically coupling the second electrode to the third electrode.
11. A multiple-state memory cell, comprising:
a first electrode coupled to a first voltage line;
a second electrode coupled to a second voltage line;
a multiple layer data state stack in which multiple data states are stored, the data-state stack including:
a first portion of a metal-doped chalcogenide material and being located between the first and second electrodes;
a third electrode of a conductive material adjoining the first portion, the third electrode being a floating electrode;
a second portion of a metal-doped chalcogenide material adjoining the third electrode,
a fourth electrode of a conductive material adjoining the second portion of a metal-doped chalcogenide material, the fourth electrode being a floating electrode, and
a third portion of a metal-doped chalcogenide material adjoining the fourth electrode.
12. The memory cell of claim 11 wherein application of a programming voltage to the first electrode induces a resistance change within at least one of the first second or third portions.
13. The memory cell of claim 11 wherein the first, second, and third portions of metal-doped chalcogenide material are a same metal-doped chalcogenide material.
14. The memory cell of claim 11 wherein at least one of the first, second, or third portions of metal-doped chalcogenide material comprises a material selected from the group consisting of germanium selenide, arsenic sulfide, germanium telluride, and germanium sulfide.
15. The memory cell of claim 11 wherein at least one of the first, second, or third portions of metal-doped chalcogenide material comprises a composition of germanium selenide.