A Min-Variance Iterative Method for Fast Smart Dummy Feature Density Assignment in Chemical-Mechanical Polishing

  • Authors:
  • Xin Wang;Charles C. Chiang;Jamil Kawa;Qing Su

  • Affiliations:
  • Synopsys Inc., Mountain View, CA;Synopsys Inc., Mountain View, CA;Synopsys Inc., Mountain View, CA;Synopsys Inc., Mountain View, CA

  • Venue:
  • ISQED '05 Proceedings of the 6th International Symposium on Quality of Electronic Design
  • Year:
  • 2005

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Abstract

Dummy feature filling is an efficient approach for reducing wafer-topography variation in chemical-mechanical polishing (CMP), which is the key planarization process in modern VLSI fabrication. In this paper, we present a new min-variance iterative method for fast smart dummy feature density assignment and post-CMP topography variation reduction. This method iteratively selects target areas using an efficient CMP low-pass filter model and a variance-minimizing heuristic, and assigns/removes dummy features accordingly. Because of the efficient usage of the 2-D Fast Fourier Transform (FFT), the computational cost of this new method is close to O(nlog(n)), making it much faster than the existing linear programming method that costs O(n^3 ). Numerical experiments show the computational cost of our new method is almost negligible when compared with the LPmethod and its solution is very close to the optimal solution.