Vertical phase change memory cell and methods for manufacturing thereof
The present invention discloses a vertical phase-change-memory (PCM) cell, comprising a stack of a bottom electrode ( 5 ) contacting a first layer of phase change material ( 14 ), a dielectric layer ( 12 ) having an opening ( 13 ), a second layer of phase change material ( 6 ) in contact with the first layer of phase change material through the opening in the dielectric layer and a top electrode ( 7 ) contacting this second layer of phase change material.
1. A phase-change memory element comprising:
a bottom electrode,
a first layer of a conductive material overlying the bottom electrode,
a patterned layer of an electrically insulating material overlying the first conductive layer,
phase-change material at least partially filling the volume in-between the pattern of the patterned layer and in ohmic contact with the first conductive layer,
a second layer of a conductive material overlying the patterned layer and in ohmic contact with the phase-change material, and
a top electrode,
wherein the volume in-between the pattern of the patterned layer comprises a plug of electrically insulating material thereby forming a closed loop gap between the plug and the perimeter of the pattern such that the ohmic contact between the phase-change material and the second conductive layer is located near this perimeter.
2. The memory element of claim 1 , wherein the first conductive layer comprises a cavity self-aligned to the pattern of the patterned layer.
3. The memory element of claim 1 , wherein the conductive material of the first and the second layer is a phase-change material.
4. The memory element of claim 3 , wherein the phase-change material of the first layer, the second layer and in the volume in-between the pattern of the patterned layer is the same phase-change material.
5. The memory element of claim 4 , wherein the phase-change material is selected from the group chalcogenides including binary, ternary or quaternary alloys such as mixtures of germanium, antimony and tellurium or mixtures of silver, indium, antimony and tellurium.
6. The memory element of claim 3 , wherein at least one of the phase-change materials of the first layer, the second layer and in the volume in-between the pattern of the patterned layer comprises a doping element.
7. The memory element of claim 6 , wherein the doping element is nitrogen and/or oxygen.
8. The memory element of claim 1 , wherein the patterned layer of an electrically insulating material is a layer of a dielectric material comprising at least one opening.
9. The memory element of claim 8 , wherein the dielectric material is selected from the group of silicon oxides, silicon nitrides, silicon oxynitrides, silicon carbides.
10. The memory element of claim 1 , wherein the plug of electrically insulating material is a plug of a dielectric material.
11. The memory element of claim 1 , wherein the phase-change material forms an active region that is a melting spot of the phase change material, and wherein the first layer of the conductive material is configured to separate the active region from the bottom electrode.
12. A method for manufacturing a phase-change memory element, comprising:
forming a bottom electrode on a substrate,
forming a first layer of conductive material over the bottom electrode,
forming a first layer of dielectric material over the first conductive layer,
forming at least one opening in the first dielectric layer to expose the underlying first conductive layer,
at least partially filling the at least one opening with phase-change material,
forming a plug of dielectric material within the partially filled at least one opening such that a closed-loop trench is created,
forming a second layer of conductive material overlying the first dielectric layer and contacting the phase-change material layer in the at least one opening, and
forming a top electrode on the second conductive layer.
13. The method of claim 12 further comprising etching a cavity in the first conductive layer self-aligned to the at least one opening.
14. The method of any of claim 12 , wherein the conductive material of the first and the second layer is a phase-change material.
15. The method of claim 14 , wherein the phase-change material of the first layer, the second layer and in the volume in-between the pattern of the patterned layer is the same phase-change material.
16. The method of claim 15 , wherein the phase-change material is selected from the group chalcogenides including binary, ternary or quaternary alloys such as mixtures of germanium, antimony and tellurium or mixtures of silver, indium, antimony and tellurium.
17. The method of claim 14 , wherein at least one of the phase-change materials of the first layer, the second layer and in the volume in-between the pattern of the patterned layer comprises a doping element.
18. The method of claim 17 , wherein the doping element is nitrogen and/or oxygen.
19. The method of claim 17 , wherein the dielectric material is selected from the group of silicon oxides, silicon nitrides, silicon oxynitrides, silicon carbides.
20. A phase-change memory element comprising:
a bottom electrode,
a first layer of a conductive material overlying the bottom electrode,
a patterned layer of an electrically insulating material overlying the first conductive layer,
phase-change material at least partially filling the volume in-between the pattern of the patterned layer and in ohmic contact with the first conductive layer,
a second layer of a conductive material overlying the patterned layer and in ohmic contact with the phase-change material, and
a top electrode,
wherein the first conductive layer comprises a cavity self-aligned to the pattern of the patterned layer.