Granted Patent B2

US 7,906,368 · App. 11/771,501 · Granted Mar 15, 2011

Abstract

Claims (24)

1. A method of forming a nonvolatile phase change memory (PCM) cell, the method comprising the steps of:

forming at least one bottom electrode on at least a portion of an upper surface of a substrate;

forming at least one phase change material layer on at least a portion of an upper surface of the bottom electrode;

forming at least one heater layer on an upper surface of the phase change material layer;

shaping the heater layer into a tapered shape, such that an upper surface of the heater layer has a cross-sectional width that is longer than a cross-sectional width of a bottom surface of the heater layer contacting the phase change material layer;

wherein the cross-sectional width of the heater layer contacting the phase change material layer is substantially the same as a cross-sectional width of an upper surface of the phase change material layer.

2. The method of claim 1 , further comprising the step of forming at least one top electrode on at least a portion of the upper surface of the heater layer.

3. The method of claim 1 , wherein the step of shaping the heater layer comprises performing a tapered etch on the heater layer.

4. The method of claim 3 , wherein the step of shaping the heater layer comprises the steps of:

depositing at least one resist layer on at least a portion of an upper surface of the heater layer;

trimming the resist layer, so that the cross-sectional width of the resist layer is a desired cross-sectional width of the upper surface of the heater layer;

performing an etch on the heater layer using the resist layer; and

removing the resist layer.

5. The method of claim 1 , further comprising a step of reducing a cross sectional width of the phase change material layer to the cross-sectional width of the bottom surface of the heater layer.

6. The method of claim 5 , wherein the step of reducing the cross sectional width of the phase change material layer comprises performing an etch on the phase change memory layer.

7. The method of claim 1 , wherein the cross-sectional width of the upper surface of the heater layer is approximately twice the cross-sectional width of the bottom surface of the heater layer.

8. The method of claim 1 , wherein the cross-sectional width of the bottom surface of the heater layer is approximately one-third of the original cross-sectional width of the heater layer.

9. The method of claim 1 , wherein the cross-sectional width of the upper surface of the heater layer is approximately two-thirds of the original cross-sectional width of the heater layer.

10. The method of claim 1 , wherein the heater material comprises TiN.

11. The method of claim 1 , wherein the phase change material layer comprises at least one chalcogenide.

12. A method of forming a nonvolatile phase change memory (PCM) cell, the method comprising the steps of:

forming at least one bottom electrode on at least a portion of an upper surface of a substrate;

forming at least one phase change material layer on at least a portion of an upper surface of the bottom electrode;

forming at least one heater layer on an upper surface of the phase change material layer, the heater layer being formed having a tapered shape such that an upper surface of the heater layer has a cross-sectional width that is longer than a cross-sectional width of a bottom surface of the heater layer contacting the phase change material layer, the cross-sectional width of the heater layer contacting the phase change material layer being substantially the same as a cross-sectional width of an upper surface of the phase change material layer contacting the heater layer.

Assignments (14)