Metal line connection for improved RRAM reliability, semiconductor arrangement comprising the same, and manufacture thereof
View Patent ↗An integrated circuit device includes an array of RRAM cells, an array of bit lines for the array of RRAM cells, and an array of source lines for the array of RRAM cells. Both the source lines and the bit lines are in metal interconnect layers above the RRAM cells. The source line are thereby provided with a higher than conventional wire size, which increases the reset speed by approximately one order of magnitude. The lifetime of the RRAM transistors and the durability of the RRAM device are consequentially improved to a similar degree.
1. An integrated circuit device, comprising:
an array of RRAM cells;
an array of bit lines connected to the RRAM cells of the array, each of the bit lines having a first cross-sectional area; and
an array of source lines for the RRAM cells of the array, each of the source lines having a second cross-sectional area;
wherein the second cross-sectional area is greater than the first cross-sectional area; and
the source lines and bit lines are configured to carry current for setting and resetting the RRAM cells.
2. The integrated circuit device of claim 1 further comprising:
an array of transistors in one-to-one correspondence with the RRAM cells, the transistors comprising source regions, drain regions, and gate electrodes;
wherein the source regions are connected to the source lines; and
the drain regions are connected to the RRAM cells.
3. The integrated circuit device of claim 2 , further comprising:
an array of word lines configured for addressing the RRAM cells;
wherein the word lines are connected to the gate electrodes.
4. The integrated circuit device of claim 3 , further comprising:
a substrate;
a plurality of metal interconnect layers at various heights above the substrate;
wherein the array of RRAM cells is located between two of the metal interconnect layers;
the source lines are located in a metal interconnect layer that is higher above the substrate than the array of RRAM cells;
the bit lines are located in a metal interconnect layer that is higher above the substrate than the array of RRAM cells; and
the word lines are located in a metal interconnect layer that is not as high above the substrate as the array of RRAM cells.
5. The integrated circuit device of claim 1 , further comprising:
a substrate;
a plurality of metal interconnect layers at various heights above the substrate;
wherein the array of RRAM cells is located between two of the metal interconnect layers; and
the source lines are located in a metal interconnect layer that is higher above the substrate than the array of RRAM cells.
6. The integrated circuit device of claim 5 , wherein:
the bit lines are connected to top electrodes of the RRAM cells; and
the bit lines are located in a metal interconnect layer that is higher above the substrate than the array of RRAM cells.
7. The integrated circuit device of claim 6 , wherein:
the source lines are located in a metal interconnect layer that is higher above the metal interconnect layer in which the bit lines are formed.
8. The integrated circuit device of claim 7 , wherein at least two metal interconnect layers are formed below the array of RRAM cells.
9. The integrated circuit device of claim 8 , further comprising:
an array of transistors formed on the substrate below the metal interconnect layers, the transistors comprising source regions, drain regions, and gate electrodes;
wherein source regions of the transistors are connected to the source lines; and
the drain regions of the transistors are connected to bottom electrodes of the RRAM cells.
10. The integrated circuit device of claim 9 , wherein at least four metal interconnect layers are formed below the array of RRAM cells.
11. The integrated circuit device of claim 1 , further comprising:
a substrate having a substrate surface; and
a plurality of metal interconnect layers above the substrate surface;
wherein the array of RRAM cells is located between two of the metal interconnect layers;
the RRAM cells comprise top electrodes, bottom electrodes, and RRAM dielectric layers between the top and bottom electrodes;
the bit lines are connected to the top electrodes;
the bottom electrodes are connected to first contacts on the substrate surface; and
the source lines are connected to second contacts on the substrate surface.
12. The integrated circuit device of claim 11 , wherein the source lines are located in a metal interconnect layer that is higher above the substrate surface than the array of RRAM cells.
13. The integrated circuit device of claim 11 , wherein the source lines are located in a metal interconnect layer that is higher above the substrate surface than the bit lines.
14. An integrated circuit (IC) device comprising:
an array of RRAM cells disposed above a substrate, wherein the array of RRAM cells is located between first and second metal interconnect layers arranged over the substrate;
a plurality of bit lines connected to the RRAM cells of the array, each of the plurality of bit lines having a first cross-sectional area;
a plurality of source lines operatively coupled to the RRAM cells of the array, each of the plurality of source lines having a second cross-sectional area, wherein the second cross-sectional area is greater than the first cross-sectional area; and
wherein the source lines are located in a third metal interconnect layer that is higher above the substrate than the array of RRAM cells.
15. The IC device of claim 14 , wherein the plurality of source lines and the plurality of bit lines are configured to carry current for setting and resetting the RRAM cells.
16. The IC device of claim 15 , wherein:
the bit lines are connected to top electrodes of the RRAM cells; and
the bit lines are located in a fourth metal interconnect layer that is higher above the substrate than the array of RRAM cells.
17. The IC device of claim 16 , wherein the third metal interconnect layer is higher above the substrate than the fourth metal interconnect layer.
18. The IC device of claim 17 , wherein at least two metal interconnect layers are located below the array of RRAM cells.
19. The IC device of claim 18 , further comprising:
an array of transistors arranged in the substrate below the metal interconnect layers, the transistors comprising source regions, drain regions, and gate electrodes;
wherein source regions of the transistors are connected to the source lines; and
the drain regions of the transistors are connected to bottom electrodes of the RRAM cells.
20. An integrated circuit (IC) device comprising:
a plurality of metal interconnect layers above a substrate;
a RRAM cell disposed above the substrate between two of the plurality of metal interconnect layers, wherein the RRAM cell comprises a top electrode, a bottom electrode, and an RRAM dielectric layer located between the top electrode and the bottom electrode;
a bit line connected to the top electrode of the RRAM cell, wherein the bit line has a first cross-sectional area;
a source line located in a metal interconnect layer that is higher above the substrate than the bit line and having a second cross-sectional area greater than the first cross-sectional area; and
a transistor device arranged within the substrate and having a first terminal connected to the bottom electrode of the RRAM cell and a second terminal connected to the source line.