RRAM structure and fabricating method of the same
An RRAM structure includes a dielectric layer. A bottom electrode, a resistive switching layer and a top electrode are disposed from bottom to top on the dielectric layer. A spacer is disposed at sidewalls of the bottom electrode, the resistive switching layer and the top electrode. The spacer includes an L-shaped spacer and a sail-shaped spacer. The L-shaped spacer contacts the sidewall of the bottom electrode, the sidewall of the resistive switching layer and the sidewall of the top electrode. The sail-shaped spacer is disposed on the L-shaped spacer. A metal line is disposed on the top electrode and contacts the top electrode and the spacer.
1 . A resistive random access memory (RRAM) structure, comprising:
a first dielectric layer;
a bottom electrode, a resistive switching layer and a top electrode disposed from bottom to top on the first dielectric layer, wherein a conductive filament can be formed within the resistive switching layer when applying bias to the top electrode and the bottom electrode;
a spacer disposed at a sidewall of the bottom electrode, a sidewall of the resistive switching layer and a sidewall of the top electrode, wherein the spacer comprises an L-shaped spacer and a sail-shaped spacer, the L-shaped spacer contacts the sidewall of the bottom electrode, the sidewall of the resistive switching layer and the sidewall of the top electrode and the sail-shaped spacer is disposed on the L-shaped spacer, the L-shaped spacer comprises a vertical element having a first end, the vertical element is perpendicular to a top surface of the first dielectric layer and a surface of the first end is horizontal; and
a first metal line disposed on the top electrode and contacting the top electrode and the spacer, wherein the first metal line overlaps the sail-shaped spacer.
2 . The RRAM structure of claim 1 , wherein the L-shaped spacer further comprises a lateral element, the lateral element is parallel to the top surface of the first dielectric layer, the first end contacts the first metal line, and the first end is lower than a topmost surface of the top electrode.
3 . The RRAM structure of claim 2 , wherein the top electrode comprises a thickness, the thickness is perpendicular to the top surface of the first dielectric layer, and the first end is aligned with half of the thickness.
4 . The RRAM structure of claim 2 , wherein the lateral element comprises a second end which is away from the bottom electrode, and a surface of the sail-shaped spacer and a surface of the second end form an arc.
5 . The RRAM structure of claim 4 , wherein a distance between the arc and the sidewall of the resistive switching layer is smaller than a width of the resistive switching layer.
6 . The RRAM structure of claim 2 , wherein the surface of the first end is parallel to the top surface of the first dielectric layer.
7 . The RRAM structure of claim 1 , wherein the first metal line contacts a top surface of the top electrode and two sidewalls of the top electrode.
8 . The RRAM structure of claim 1 , wherein a width of the first metal line is greater than a width of the top electrode.
9 . The RRAM structure of claim 1 , wherein material of the L-shaped spacer is different from material of the sail-shaped spacer.
10 . The RRAM structure of claim 1 , wherein material of the L-shaped spacer comprises silicon nitride.
11 . The RRAM structure of claim 1 , wherein the first metal line contacts the sail-shaped spacer.
12 . The RRAM structure of claim 1 , wherein the first dielectric layer comprises one or multiple insulating layers comprising silicon oxide, silicon nitride, silicon carbon nitride, silicon oxynitride or silicon carbon oxynitride.
13 . The RRAM structure of claim 1 , wherein the first metal line comprises copper, aluminum or tungsten.
14 . The RRAM structure of claim 1 , further comprising a second dielectric layer covering the first dielectric layer, and the second dielectric layer comprises a recess.
15 . The RRAM structure of claim 14 , wherein the first metal line is disposed in the recess.
16 . The RRAM structure of claim 14 , wherein the L-shaped spacer and the sail-shaped spacer together serve as an etching stop layer when forming the recess.
17 . The RRAM structure of claim 1 , wherein the resistive switching material layer comprises tantalum oxide, nickel oxide, or hafnium oxide.
18 . The RRAM structure of claim 1 , further comprising a conductive plug in the first dielectric layer and under the bottom electrode, and a width of the conductive plug is smaller than a width of the resistive switching layer.
19 . The RRAM structure of claim 1 , further comprising a second metal line disposed at one side of the first metal line, and a depth of the second metal line and a depth of the first metal line are the same.
20 . The RRAM structure of claim 1 , wherein the first dielectric layer comprises a flat top surface, and the bottom electrode and the spacer contact the flat top surface.