Dual port memory cell with reduced coupling capacitance and small cell size
View Patent ↗A dual or multi port memory device including a first group of bit lines associated with the first port a second group of bit lines associated with the second port, wherein the bit lines are arranged in different metalization layers and separated horizontally to reduce one or both of stray and coupling capacitance associated with the bit lines. In one exemplary embodiment, the bit lines from each port that are in closer proximity to the bit lines of the other (or another) port are disposed in different metallization layers to reduce coupling capacitance therebetween. One or more further embodiments can include V SS or V DD line(s) located horizontally between the bit lines and metal to substrate contacts for the bit lines can be formed in opposite corners of the memory device to further reduce capacitance.
1. A multi port memory device including a first port and a second port, the memory device comprising:
a first group of bit lines associated with the first port, the first group of bit lines including a first bit line;
a second group of bit lines associated with the second port, the second group of bit lines including a second bit line, wherein the second bit line is disposed in closer proximity to any of the first group of bit lines than any of the remaining bit lines in the second group of bit lines, and the first bit line is disposed in closer proximity to any of the second group of bit lines than any of the remaining bit lines in the second group of bit lines;
wherein the first bit line and the second bit line are formed in different metallization layers; and
wherein the second group of bit lines is separated in at least one direction of a horizontal plane from the first group of bit lines.
2. The memory device of claim 1 , wherein one or both of stray or coupling capacitance associated with the bit lines is reduced due to the vertical and/or horizontal separation between the bit lines.
3. The memory device of claim 1 further comprising first metal-to-substrate contacts of the first group of bit lines arranged in an opposite corner of the multi-port memory device from second metal-to-substrate contacts of the second group of bit lines.
4. The memory device of claim 1 further comprising a V SS or V DD line located horizontally between and separating the first group of bit lines and the second group of bit lines.
5. The memory device of claim 4 further comprising a V SS or V DD line located horizontally between and separating the first group of bit lines and the second group of bit lines.
6. The memory device of claim 1 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
7. The memory device of claim 3 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
8. The memory device of claim 4 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
9. The memory device of claim 5 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
10. A multi port memory device including a first port and a second port, the memory device comprising:
a first group of bit lines associated with the first port, the first group of bit lines including a first bit line and a third bit line;
a second group of bit lines associated with the second port, the second group of bit lines including a second bit line and a fourth bit line, wherein the second bit line is disposed in closer proximity to any of the first group of bit lines than any of the remaining bit lines in the second group of bit lines, and the first bit line is disposed in closer proximity to any of the second group of bit lines than any of the remaining bit lines in the second group of bit lines;
wherein the first bit line, the second bit line, the third bit line, and the fourth bit line are formed in different metallization layers; and
wherein the second group of bit lines is separated in at least one direction of a horizontal plane from the first group of bit lines.
11. The memory device of claim 10 , wherein one or both of stray or coupling capacitance associated with the bit lines is reduced due to the vertical and/or horizontal separation between the bit lines.
12. The memory device of claim 10 further comprising first metal-to-substrate contacts of the first group of bit lines arranged in an opposite corner from second metal-to-substrate contacts of the second group of bit lines.
13. The memory device of claim 10 further comprising a V SS or V DD line located horizontally between and separating the first group of bit lines and the second group of bit lines to reduce coupling capacitance.
14. The memory device of claim 12 further comprising a V SS or V DD line located horizontally between and separating the first group of bit lines and the second group of bit lines to reduce coupling capacitance.
15. The memory device of claim 10 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
16. The memory device of claim 12 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
17. The memory device of claim 13 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
18. The memory device of claim 14 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
19. A multi port memory device including a first port and a second port, the memory device comprising:
a first group of bit lines associated with the first port, the first group of bit lines including a first bit line and a third bit line;
a second group of bit lines associated with the second port, the second group of bit lines including a second bit line and a fourth bit line, wherein the second bit line is disposed in closer proximity to any of the first group of bit lines than any of the remaining bit lines in the second group of bit lines, and the first bit line is disposed in closer proximity to any of the second group of bit lines than any of the remaining bit lines in the second group of bit lines;
wherein the first bit line and the fourth bit line are disposed in a metallization layer, the second bit line and the third bit line are disposed in another metallization layer, wherein the metallization layer and the another metallization layer are formed as different layers;
wherein the second group of bit lines is separated in at least one direction of a horizontal plane from the first group of bit lines.
20. The memory device of claim 19 , wherein one or both of stray or coupling capacitance associated with the bit lines is reduced due to the vertical and/or horizontal separation between the bit lines.
21. The memory device of claim 19 further comprising first metal-to-substrate contacts of the first group of bit lines arranged in an opposite corner from second metal-to-substrate contacts of the second group of bit lines.
22. The memory device of claim 19 further comprising a V SS or V DD line located horizontally between and separating the first group of bit lines and the second group of bit lines to reduce coupling capacitance.
23. The memory device of claim 21 further comprising a V SS or V DD line located horizontally between and separating the first group of bit lines and the second group of bit lines to reduce coupling capacitance.
24. The memory device of claim 19 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
25. The memory device of claim 21 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
26. The memory device of claim 22 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.
27. The memory device of claim 23 further comprising a vertical shielding metal layer located horizontally between and separating the first group of bit lines and the second group of bit lines.