Memory cell with an asymmetrical area
View Patent ↗An asymmetric-area memory cell, and a fabrication method for forming an asymmetric-area memory cell, are provided. The method comprises: forming a bottom electrode having an area; forming a CMR memory film overlying the bottom electrode, having an asymmetric area; and, forming a top electrode having an area, less than the bottom electrode area, overlying the CMR film. In one aspect, the CMR film has a first area adjacent the top electrode and a second area, greater than the first area, adjacent the bottom electrode. Typically, the CMR film first area is approximately equal to the top electrode area, although the CMR film second area may be less than the bottom electrode area.
1. An asymmetric-area memory cell comprising:
a bottom electrode having an area;
a colossal magnetoresistance (CMR) memory film overlying the bottom electrode, having an asymmetric area;
a top electrode having an area, less than the bottom electrode area, overlying the CMR memory film; and,
wherein the CMR memory film has a first area adjacent the top electrode and a second area, greater than the first area, adjacent the bottom electrode.
2. The memory cell of claim 1 wherein the CMR memory film first area is approximately equal to the top electrode area.
3. The memory cell of claim 2 wherein the CMR memory film second area is less than the bottom electrode area.
4. The memory cell of claim 3 wherein the CMR memory film has an overall first thickness, a second thickness portion of the CMR memory film with the first area, and a third thickness portion of the CMR memory film with the second area underlying the second thickness portion of the CMR memory film with the first area, where the third thickness of the CMR memory film with the second area is equal to the CMR memory film overall first thickness minus the second thickness portion of the CMR memory film with the first area.
5. The memory cell of claim 4 further comprising:
a first set of sidewall insulators adjacent the top electrode and the second thickness portion of the CMR memory film with the first area; and,
a second set of sidewall insulators overlaying the first set of sidewall insulators and adjacent the third thickness portion of the CMR memory film with the second area.
6. The memory cell of claim 5 wherein the third thickness portion of the CMR memory film with the second area is in the range of 20 to 80% of the CMR memory film overall first thickness.
7. The memory cell of claim 4 wherein the CMR memory film overall first thickness is in the range of 50 to 350 nanometers.
8. The memory cell of claim 5 wherein the first set of sidewall insulators is formed from a material selected from the group including silicon nitride and aluminum oxide, each sidewall having a thickness in the range of 50 to 200 nanometers (nm).
9. The memory cell of claim 8 wherein the second set of sidewall insulators is formed from a material selected from the group including silicon nitride and aluminum oxide, each sidewall having a thickness in the range of 20 to 100 nm.
10. The memory cell of claim 1 wherein the bottom electrode is formed from a material selected from the group including TiN/Ti, Pt/TiN/Ti, In/TiN/Ti, PtRhOx compounds, and PtIrOx compounds; and,
wherein the top electrode is formed from a material selected from the group including TiN, TiN/Pt, TiN/In, PtRhOx compounds, and PtIrOx compounds.
11. The memory cell of claim 1 wherein the CMR memory film is formed from Pr 0.3 Ca 0.7 MnO 3 (PCMO).
12. An RRAM asymmetric-area memory cell comprising:
a CMOS transistor with source and drain active regions;
a metal interlevel interconnect overlying a transistor active region;
a bottom electrode having an area, overlying the metal interlevel interconnect;
a colossal magnetoresistance (CMR) memory film overlying the bottom electrode, having an asymmetric area;
a top electrode having an area, less than the bottom electrode area, overlying the CMR memory fi 1 m; and,
wherein the CMR memory film has a first area adjacent the top electrode and a second area, greater than the first area, adjacent the bottom electrode.