Model-based dummy feature placement for oxide chemical-mechanical polishing manufacturability

Abstract

Chemical-mechanical polishing (CMP) is an enabling technique used in deep-submicron VLSI manufacturing to achieve uniformity in long range oxide planarization [1]. Post-CMP oxide topography is highly related to local spatial pattern density in layout. To change local pattern density, and thus ensure post-CMP planarization, dummy features are placed in layout. Based on models that accurately describe the relation between local pattern density and post-CMP planarization [7; 5; 9], a two-step procedure of global density assignment followed by local insertion is proposed to solve the dummy feature placement problem in the fixed-dissection regime with both single-layer and multiple-layer considerations. Two experiments, conducted with real design data, gave excellent results by reducing post-CMP topography variation from 767Å to 152Å in the single-layer formulation and by avoiding cumulative effect in the multiple-layer formulation. The result from single-layer formulation compares very favorably both to the rule-based approach widely used in industry and to the algorithm in [3]. The multiple-layer formulation has no previously published work.