MIMCAP creation and utilization methodology
A metal-insulator-metal (MIM) capacitor design methodology and system substantially maximizes the benefits of including MIM capacitors in an integrated circuit design while substantially minimizing the negative impacts resulting from increased capacitance. A process analysis is performed on an integrated circuit design to determine a metal layer that is likely to be most adversely affected by the presence of MIM capacitor cells. The MIM capacitor cells are then designed to have specific sizes and orientations based on results of the process analysis, taking the most affected metal layer into consideration. Finally, the MIM capacitor cells are placed at selected locations on the die in an algorithmic fashion in order to satisfy a design target of maximizing coverage area while avoiding interference with signal paths and critical or sensitive components.
1. A semiconductor chip, comprising:
a first metal layer;
a second metal layer; and
metal-insulator-metal (MIM) capacitor cells between the first metal layer and the second metal layer,
wherein
the MIM capacitor cells have substantially equal widths,
the MIM capacitor cells have varying lengths, and
the MIM capacitor cells are oriented to cause a lengthwise direction of the MIM capacitor cells to match a routing orientation of the first metal layer when the first metal layer is more impacted by a capacitance increase caused by inclusion of the MIM capacitor cells than the second metal layer.
2. The semiconductor chip of claim 1 , wherein a MIM capacitor cell of the MIM capacitor cells comprises a capacitor top metal node, a capacitor bottom metal node, power connectivity, and ground connectivity.
3. The semiconductor chip of claim 1 , wherein the widths are approximately equal to a width of a power grid of the metal layer that is more impacted by the capacitance increase.
4. The semiconductor chip of claim 1 , wherein the MIM capacitor cells are placed on the semiconductor chip at locations that avoid overlap with signal paths on the first metal layer and the second metal layer.
5. The semiconductor chip of claim 4 , wherein the MIM capacitor cells are placed on the semiconductor chip at locations that avoid overlap between the MIM capacitor cells and at least one of a critical cell located on the first metal layer or the second metal layer, a sensitive circuit located on the first metal layer or the second metal layer, an electrostatic discharge cell located on at least one of the first metal layer or the second metal layer, or a circuit associated with a different power domain relative to the MIM capacitor cells.
6. The semiconductor chip of claim 5 , wherein the MIM capacitor cells are placed on an available area of a layer between the first metal layer and the second metal layer such that uncovered areas, of the available area, on which no MIM capacitor cell is placed and which do not overlap with the signal paths or the at least one of the critical cell or the sensitive circuit are not large enough to accommodate a MIM capacitor cell of a shortest length of the varying lengths.
7. The semiconductor chip of claim 1 , wherein the MIM capacitor cells respectively comprise a capacitor top metal node, a capacitor bottom metal node, a power connection, and a ground connection.
8. The semiconductor chip of claim 1 , wherein the respective lengths of the MIM capacitor cells conform to one of a set of different defined lengths.
9. The semiconductor chip of claim 1 , further comprising blocking areas of a layer comprising the MIM capacitor cells, wherein the blocking areas represent areas that are not to be covered by MIM capacitor cells.
10. The semiconductor chip of claim 1 , wherein the MIM capacitor cells are oriented instead to cause a lengthwise direction of the MIM capacitor cells to match a routing orientation of the second metal layer when the second metal layer is more impacted by a capacitance increase caused by inclusion of the MIM capacitor cells than the first metal layer.
11. An integrated circuit, comprising:
a metal-insulator-metal (MIM) capacitor layer in which MIM capacitor cells are formed;
a first metal layer that neighbors a top side of the MIM capacitor layer; and
a second metal layer that neighbors a bottom side of the MIM capacitor layer,
wherein
the MIM capacitor cells are oriented lengthwise in a same direction as a routing orientation of the first metal layer when the first metal layer is more impacted by a capacitance increase caused by inclusion of the MIM capacitor cells than the second metal layer;
the MIM capacitor cells have equal widths that are substantially equal to a width of a power grid of the metal layer;
the MIM capacitor cells have varying lengths corresponding to a set of defined lengths; and
the MIM capacitor cells are placed on the integrated circuit at areas of the MIM capacitor layer that avoid overlap between the MIM capacitor cells and signal paths located on the first metal layer and the second metal layer.
12. The integrated circuit of claim 11 , wherein the MIM capacitor cells are placed on the integrated circuit at areas of the MIM capacitor layer that further avoid overlap between the MIM capacitor cells and at least one of a critical cell or a sensitive circuit located on the first metal layer or the second metal layer.
13. The integrated circuit of claim 12 , wherein the MIM capacitor cells are placed on the MIM capacitor layer such that there are no uncovered areas of the MIM capacitor layer that do not overlap with the signal paths or the at least one of the critical cell or the sensitive circuit, and that are large enough to accommodate one of the MIM capacitor cells having a shortest length of the set of defined lengths and oriented lengthwise in the same direction as the routing orientation of the metal layer.
14. The integrated circuit of claim 11 , wherein the MIM capacitor cells respectively comprise a capacitor top metal node, a capacitor bottom metal node, a power connection, and a ground connection.
15. The integrated circuit of claim 11 , wherein the respective lengths of the MIM capacitor cells conform to one of a set of different defined lengths.
16. The integrated circuit of claim 11 , further comprising blocking areas of a layer comprising the MIM capacitor cells, wherein the blocking areas represent areas that are not to be covered by MIM capacitor cells.
17. The integrated circuit of claim 11 , wherein a MIM capacitor cell of the MIM capacitor cells comprises a capacitor top metal node, a capacitor bottom metal node, power connectivity, and ground connectivity.
18. The integrated circuit of claim 11 , wherein the widths are approximately equal to a width of a power grid of the metal layer that is more impacted by the capacitance increase.
19. The integrated circuit of claim 11 , wherein the MIM capacitor cells are instead oriented lengthwise in a same direction as a routing orientation of the second metal layer when the second metal layer is more impacted by a capacitance increase caused by inclusion of the MIM capacitor cells than the first metal layer.