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

Chemical-mechanical polishing (CMP) is an enabling technique used in deep-s ubmicrometer 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 planari zation, dummy features are placed in the layout. Based on models that accur ately describe the relation between local pattern density and post-CMP plan arization by Stine et al, (1997), Ouma et at (1998), and Yu et at (1999), a two-step procedure of global density assignment followed by local insertio n is proposed to solve the dummy feature placement problem in the fixed-dis section regime with both single-layer and multiple-layer considerations, Tw o experiments conducted with real design layouts gave excellent results by reducing simulated post-CMP topography variation from 767 Angstrom to 152 A ngstrom in the single-layer formulation and by avoiding cumulative effect i n the multiple-layer formulation. The simulation result from single-layer f ormulation compares very favorably both to the rule-based approach widely u sed in industry and to the algorithm by Kahng et at (1999), The multiple-la yer formulation has no previously published work.