Via antenna fix in deep sub-micron circuit designs
A filler cell for use in fabricating an integrated circuit. The filler cell couples a power supply rail of an adjacent logic cell to a power supply rail of another adjacent logic cell. The filler cell also has a diode to bleed charge accumulated on the power rails of the adjacent logic cells to the substrate. The diode is reverse biased during normal integrated circuit operation. A method for fabricating an integrated circuit with a power grid. At least one filler cell is placed on the integrated circuit to bleed away charge accumulated on the power grid during the fabrication of the integrated circuit. The filler cell is connected to a supply rail of an adjacent logic cell.
1. A filler cell for use in fabricating an integrated circuit having a substrate, the filler cell comprising:
a first cell comprising:
an interconnect to directly connect a V ss power supply rail of a first adjacent logic cell of the integrated circuit to a corresponding V ss power supply rail of a second adjacent logic cell of the integrated circuit; and
a diode cell comprising a diode operably coupled between a V dd power supply rail of the first adjacent logic cell and the substrate such that the diode is reverse biased during normal integrated circuit operation; and
wherein the diode cell bleeds charge accumulated on the V dd power rail during fabrication of the integrated circuit to the substrate.
2. The filler cell of claim 1 wherein the diode is a pn junction.
3. The filler cell of claim 1 wherein the interconnect is fabricated from a material chosen from the group consisting of copper, gold, aluminum, tungsten, titanium, silver, and polysilicon.
4. The filler cell of claim 1 wherein the diode cell is located within the first cell.
5. An integrated circuit having a substrate and a power grid, comprising:
a plurality of logic cells;
at least one filler cell operable to bleed away charge accumulated on the power grid during fabrication to the substrate, the at least one filler cell comprising:
an interconnect to direct connect a V ss power supply rail of an adjacent logic cell to a corresponding V ss power supply rail of another adjacent logic cell; and
a diode operably coupled between a V dd power supply rail of the adjacent logic cell and the substrate to bleed away the charge.
6. The integrated circuit of claim 5 wherein the filler cell further comprises:
a diode cell comprising the diode operably coupled to the V dd power supply rail and the substrate such that the diode is reverse biased during normal integrated circuit operation; and
wherein the diode cell bleeds charge accumulated on the V dd power supply rail during fabrication of the integrated circuit to the substrate.
7. The integrated circuit of claim 6 wherein the diode cell is a pn junction.
8. The integrated circuit of claim 5 further comprising: at least
one transistor having its gate connected to the power grid; and wherein the
filler cell is configured to protect the transistor from damage due to a charge build-up on the power grid during integrated circuit fabrication.