PCM cell with nanoheater surrounded with airgaps
A phase change memory (PCM) device is provided. The PCM device includes a bottom electrode formed on a substrate, a heater electrode formed on the bottom electrode, the heater electrode having a tapered portion that becomes narrower in a direction away from the substrate. The PCM device also includes an interlayer dielectric (ILD) layer formed on the tapered portion of the heater electrode, the interlayer layer dielectric including an airgap that at least partially surrounds the tapered portion of the heater electrode. The PCM device also includes a phase change layer formed on the heater electrode, and a top electrode formed on the phase change layer.
1. A method of manufacturing a phase change memory (PCM) device, the method comprising:
forming a bottom electrode on a substrate;
forming a heater electrode on the bottom electrode, the heater electrode having a tapered portion that becomes narrower in a direction away from the substrate;
forming an interlayer dielectric (ILD) layer on the tapered portion of the heater electrode, the interlayer layer dielectric including an airgap that at least partially surrounds the tapered portion of the heater electrode;
forming a phase change layer on the heater electrode; and
forming a top electrode on the phase change layer.
2. The method according to claim 1 , wherein forming the heater electrode includes:
forming a heater electrode layer;
forming a dielectric cap on the heater electrode layer;
forming a sidewall spacer layer on sidewalls of the heater electrode layer and the dielectric cap layer.
3. The method according to claim 2 , wherein forming the heater electrode further includes:
forming the ILD layer around the sidewall spacer layer;
recessing the sidewall spacer layer to a level that is below an upper surface of the heater electrode layer; and
performing an isotropic etch on the heater electrode layer to form the heater electrode having the tapered portion.
4. The method according to claim 3 , wherein an upper tip portion of the heater electrode has a width that is less than a width of the dielectric cap.
5. The method according to claim 3 , further comprising:
removing the dielectric cap; and
forming an etch stop layer on the PCM device having openings therein corresponding to a location of the phase change layer, the phase change layer being formed in direct contact with an upper surface of the heater electrode.
6. The method according to claim 3 , wherein the sidewall spacer layer is recessed to a level that is above a lower surface of the heater electrode layer.
7. The method according to claim 1 , wherein a width of the phase change layer is greater than a width of the tapered portion of the heater electrode.
8. The method according to claim 1 , wherein the heater electrode comprises TiN.
9. The method according to claim 1 , wherein the tapered portion of the heater electrode has a shape that is selected from the group consisting of conical, pyramidic, and asymptotic.
10. The method according to claim 1 , wherein the phase change layer includes at least one selected from the group consisting of GeSe, AsS, SbTe and In 2 Se 3 GeAsTe, or GeSbTe (GST).
11. A phase change memory (PCM) device comprising:
a bottom electrode formed on a substrate;
a heater electrode formed on the bottom electrode, the heater electrode having a tapered portion that becomes narrower in a direction away from the substrate;
an interlayer dielectric (ILD) layer formed on the tapered portion of the heater electrode, the interlayer layer dielectric including an airgap that at least partially surrounds the tapered portion of the heater electrode;
a phase change layer formed on the heater electrode; and
a top electrode formed on the phase change layer.
12. The PCM device according to claim 11 , further comprising a sidewall spacer layer formed on sidewalls of the heater electrode.
13. The PCM device according to claim 12 , wherein a height of the sidewall spacer layer is less than a height of the heater electrode.
14. The PCM device according to claim 13 , wherein an upper tip portion of the heater electrode has a width that is less than a width of the phase change layer.
15. The PCM device according to claim 13 , further comprising an etch stop layer formed on the PCM device having openings therein corresponding to a location of the phase change layer, the phase change layer being formed in direct contact with an upper surface of the heater electrode.
16. The PCM device according to claim 11 , wherein the heater electrode comprises TiN.
17. The PCM device of claim 11 , wherein the tapered portion of the heater electrode has a shape that is selected from the group consisting of conical, pyramidic, and asymptotic.
18. The PCM device of claim 11 , wherein the phase change layer includes at least one selected from the group consisting of GeSe, AsS, SbTe and In 2 Se 3 GeAsTe, or GeSbTe (GST).
19. The PCM device of claim 11 , wherein the ILD layer comprises SiN.
20. The PCM device of claim 11 , wherein the ILD layer includes a first ILD layer comprising SiN and a second ILD layer comprising SiOCN that is formed on the first ILD layer.