Method for forming a PCRAM with low reset current

1. A method comprising:

forming a first interlayer dielectric (ILD) over a bottom electrode;

removing a portion of the first ILD, forming a cell area;

forming a u-shaped heater liner within the cell area;

forming an interlayer dielectric structure within the u-shaped heater liner, the interlayer dielectric structure including a protruding portion extending above a top surface of the first ILD;

forming a phase-change layer on side surfaces of the protruding portion and/or on the first ILD surrounding the protruding portion; and

forming a dielectric spacer surrounding the protruding portion.

2. A method according to claim 1 , comprising:

forming the phase-change layer on the first ILD; and

removing a portion of the phase-change layer vertically contiguous with the portion of the first ILD, prior to forming the u-shaped heater liner.

3. A method according to claim 2 , comprising:

forming the u-shaped heater liner within the cell area and between the phase-change layer and the protruding portion with a top surface of the u-shaped heater liner being coplanar with a top surface of the phase-change layer.

4. A method according to claim 1 , comprising:

forming the phase-change layer on the first ILD;

forming the dielectric spacer on the phase-change layer; and

removing a portion of the phase-change layer from the first ILD not under the dielectric spacer.

5. A method according to claim 1 , further comprising:

forming a second ILD over the phase-change layer; and

forming the protruding portion to a height that is coplanar with a top surface of the second ILD.

6. A method according to claim 1 , further comprising:

forming a second ILD over the first ILD prior to forming the phase-change layer; and

removing a portion of the second ILD vertically contiguous with the portion of the first ILD, prior to forming the u-shaped heater liner.

7. A method according to claim 1 , comprising:

forming the phase-change layer on side surfaces of the protruding portion; and

forming the dielectric spacer surrounding the phase-change layer.

8. A method according to claim 1 , comprising:

forming the phase-change layer on side surfaces of the protruding portion and on the first ILD; and

forming the dielectric spacer above the phase-change layer on the first ILD and surrounding the phase-change layer on the side surfaces of the protruding portion.

9. A method according to claim 1 , further comprising forming a top electrode over the first ILD, the dielectric spacer, and the protruding portion.

10. A method comprising:

forming a first interlayer dielectric (ILD) over a bottom electrode;

forming a second ILD on the first ILD;

removing a portion of the first and second ILDs, forming a cavity;

conformally depositing a heater liner over the second ILD and within the cavity;

planarizing the heater liner down to the second ILD;

filling the cavity with an interlayer dielectric material;

removing a portion of the heater liner adjacent the second ILD and the second ILD, leaving a portion of the interlayer dielectric material protruding from the cavity;

forming a phase-change layer on side surfaces of the protruding portion and/or on the first ILD surrounding the protruding portion;

forming a dielectric spacer surrounding the protruding portion; and

forming a top electrode over the first ILD, the dielectric spacer, and the protruding portion.