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

Chemical-mechanical polishing (CMP) is an enabling technique used in deep-submicrometer VLSI manufacturing to achieve long range oxide planarization. Post-CMP oxide topography is highly related to local pattern density in the layout. To change local pattern density and, thus, ensure post-CMP planarization, dummy features are placed in the layout. Based on models that accurately describe the relation between local pattern density and post-CMP planarization by Stine et al. (1997), Ouma et al. (1998), and Yu et al. (1999), 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 layouts gave excellent results by reducing simulated post-CMP topography variation from 767 Å to 152 Å in the single-layer formulation and by avoiding cumulative effect in the multiple-layer formulation. The simulation result from single-layer formulation compares very favorably both to the rule-based approach widely used in industry and to the algorithm by Kahng et al. (1999). The multiple-layer formulation has no previously published work.