Twisted wordline strapping arrangement
AssigneeAtmos Corporation
InventorWlodek Kurjanowicz
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Abstract
A high density wordline strapping arrangement is obtained by routing three primary metal-2 wordline straps in the same space as four polysilicon wordline, and routing the fourth wordline strap in a metal-4 layer over the primary metal-2 wordline straps. Stitches in metal-3 connect metal-2 primary wordline straps to metal-4 wordline straps. Therefore, contact spacing and metal pitch limitations are relaxed to allow four metal wordline straps to occupy the same pitch as four polysilicon wordlines. The wordlines are twisted to keep the fully balanced and to minimise coupling between wordline straps and neighbouring power and signal lines. Hence, a smaller memory cell array can be formed according to the wordline packing arrangement of the present invention.
Claims9
A wordline strapping arrangement for a semiconductor memory array, comprising:
- a plurality of wordlines formed in a polysilicon layer of the semiconductor memory array;
- stitches formed in a first conductive layer overlaying the polysilicon layer, the stitches having a predetermined configuration in each of successive stitching regions, and being coupled to the plurality of wordlines in each of the successive stitching regions to provide an effective twisting of the plurality of wordlines such that the plurality of wordlines are balanced over their length;
- at least one bypass strap formed in a second conductive layer superjacent the polysilicon layer, each at least one bypass strap being coupled to one of the stitches in each successive stitching region;
- primary straps formed in a third conductive layer superjacent the polysilicon layer, the primary straps in the third conductive layer being coupled, in each of the successive stitching regions, to separate ones of the stitches not coupled to the at least one bypass strap.
The wordline strapping arrangement of claim 8, wherein there are three primary straps and four wordlines.
Dependencies are inferred from the claim text.