MIMcap creation and utilization methodology
View Patent ↗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 method for placement of metal-insulator-metal (MIM) capacitors on a semiconductor chip, comprising:
analyzing, by a system comprising a processor, design information relating to an integrated circuit design;
identifying, by the system based on a result of the analyzing, which metal layer, of a first metal layer or a second metal layer, has a likelihood of being more affected by additional parasitic capacitance introduced by presence of MIM capacitor cells; and
setting, by the system, a lengthwise orientation of the MIM capacitor cells on the semiconductor chip that matches a routing orientation of the metal layer that has the likelihood of being more affected by the additional parasitic capacitance.
2. The method of claim 1 , further comprising setting, by the system, widths of the MIM capacitor cells to be approximately equal to a width of a power grid of the metal layer that has the likelihood of being more affected by the additional parasitic capacitance.
3. The method of claim 2 , further comprising setting, by the system, respective lengths of the MIM capacitor cells to conform to one of a set of different defined lengths.
4. The method of claim 3 , further comprising determining, by the system, blocking areas of a layer in which the MIM capacitor cells are to be placed, wherein the blocking areas represent areas that are not to be covered by MIM capacitor cells.
5. The method of claim 4 , wherein the determining the blocking areas comprise at least one of determining an area corresponding to a signal path on at least one of the first metal layer or the second metal layer, determining an area corresponding to electrostatic discharge cells on at least one of the first metal layer or the second metal layer, determining an area corresponding to a critical cell on at least one of the first metal layer or the second metal layer, determining an area corresponding to a sensitive circuit on at least one of the first metal layer or the second metal layer, or determining an area corresponding to a circuit associated with a different power domain relative to the MIM capacitor cells.
6. The method of claim 4 , further comprising:
selecting a longest length of the set of different defined lengths; and
selecting a location, on an uncovered area of the layer that has not yet been covered by a MIM capacitor cell and that does not overlap with one of the blocking areas, for placement of one of the MIM capacitor cells corresponding to the longest length, wherein the determining the location comprises setting the lengthwise orientation of the one of the MIM capacitor cells to match the routing orientation of the metal layer that has the likelihood of being more affected by the presence of the MIM capacitor cells.
7. The method of claim 6 , further comprising:
in response to determining that a remaining portion of the uncovered area has a size capable of accommodating another MIM capacitor cell corresponding to the longest length and having the lengthwise orientation that matches the routing orientation, selecting another location on the uncovered area for placement of another of the MIM capacitor cells corresponding to the longest length; and
in response to determining that no remaining portions of the uncovered area have the size capable of accommodating another MIM capacitor cell corresponding to the longest length and having the lengthwise orientation that matches the routing orientation:
selecting a next longest length of the set of different defined lengths; and
selecting another location on the uncovered area that has not yet been covered by a MIM capacitor cell and that does not overlap with one of the blocking areas for placement of another of the MIM capacitor cells corresponding to the next longest length.
8. The method of claim 7 , further comprising, in response to determining that no remaining portions of the uncovered area have a size capable of accommodating a MIM capacitor cell corresponding to a shortest length of the set of different defined lengths, ending placement of the MIM capacitor cells and generating output data identifying locations and sizes of the MIM capacitor cells on the semiconductor chip.
9. The method of claim 8 , wherein the generating the output data comprises at least one of modifying the design data to include the locations and sizes of the MIM capacitor cells to yield modified design data, generating a schematic illustrating the sizes and locations of the MIM capacitor cells, or generating a text-based output identifying the locations and sizes of the MIM capacitor cells.
10. The method of claim 8 , further comprising sending the output data to a semiconductor chip fabrication system.