| US 7,594,213 B2 | ||
| Method and apparatus for computing dummy feature density for chemical-mechanical polishing | ||
| Xin Wang, Pasadena, Calif. (US); Charles C. Chiang, San Jose, Calif. (US); and Jamil Kawa, Campbell, Calif. (US) | ||
| Assigned to Synopsys, Inc., Mountain View, Calif. (US) | ||
| Filed on Nov. 24, 2004, as Appl. No. 10/997,396. | ||
| Claims priority of provisional application 60/524786, filed on Nov. 24, 2003. | ||
| Prior Publication US 2005/0114824 A1, May 26, 2005 | ||
| Int. Cl. G06F 17/50 (2006.01) | ||
| U.S. Cl. 716—10 [716/2; 716/4; 716/19; 716/21] | 21 Claims |
| 1. A method for computing dummy feature density for a CMP (Chemical-Mechanical Polishing) process, wherein the dummy feature
density is used to add dummy features to a layout to reduce a post-CMP topography variation, the method comprising:
discretizing a layout of an integrated circuit into a plurality of panels;
computing a feature density and a slack density for the plurality of panels, wherein the feature density d(i, j) for panel
(i, j) specifies the density of features in the panel and the slack density S(i, j) for the panel specifies the maximum density
of dummy features that can be added to the panel; and
computing a dummy feature density for the plurality of panels by, iteratively,
calculating an effective feature density ρ0(i, j) for the plurality of panels using the feature density and a function f(i, j) that models the CMP process, wherein decreasing
the effective feature density variation decreases the post-CMP topography variation;
calculating a filling amount Δ(i, j) for a set of panels in the plurality of panels using a target effective feature density
t(i, j), the effective feature density, and the slack density; and
updating the feature density, the slack density, and the dummy feature density for the set of panels using the filling amount;
wherein a convergence rate of the dummy feature density computation is increased because, in each iteration, the method updates
the dummy feature density for the set of panels, instead of updating the dummy feature density for only a single panel.
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