Energy-Minimization Model for Fill Synthesis

Abstract

Although fill allocation methods to enable reduced metal height variations and manually applicable design guidelines to reduce coupling capacitances are available, the synthesis of fills according to these allocations or guidelines is not well automated. Current fill insertion algorithms mostly use simple mask operations, which fail to enable the implementation of complex design guidelines. The proposed fill synthesis model not only enables implementation of such guidelines, but is also suitable for insertion of standard fill patterns. The proposed novel model has an intricate analogy to the electrons filling the orbits of an atom. Through the proposed method, the task of designing an optimal fill configuration is carried to the CAD tool designer in terms of designing a suitable energy network or rules, albeit in an easier way through provided insights and models.

Key directions and a roadmap for electrical design for manufacturability

“…A force-directed scheme to optimize fill shapes and locations was first proposed in [1]. Our present work is simpler (e.g., without an "atomistic" physical analogy), and validated through parasitic extraction and timing analysis of standard-cell designs.…”

“…Xiang et al have proposed a slot-based coupling-aware fill insertion method in [18]. Although mentioned as the first such algorithm for coupling awareness, this work was subsequent to [1]. Furthermore, no timing impact and density variation analyses are provided.…”

“…More detailed fill impact analysis, including inter-layer impacts, were provided in [2]. A hour-glass fill pattern for optimal intra-layer coupling was identified in [1]. However, known fill synthesis algorithms cannot effectively apply these rules, and manual application is impractical.…”

“…In this paper, we develop a fill insertion method that heuristically minimizes coupling capacitance increase due to fill. Our optimization methodology builds on fill insertion guidelines previously developed in, e.g., [12] and [1]. Experiments show that the proposed optimization methods can reduce fill impact on coupling capacitances by up to 85% for 30% pattern density and up to 65% for 60% pattern density cases.…”

Detailed Placement for Enhanced Control of Resist and Etch CDs

“…In a recent work, Topolaglu [71] proposes a CMP fill synthesis framework which uses coupling-aware fill insertion guidelines to reduce the impact of CMP fill shapes on the design's performance. In another work, Xiang et al [67] propose a coupling-aware constrained CMP-fill analysis algorithm which identifies feasible locations for fill features such that the fill-induced coupling capacitance can be bounded within the given coupling threshold of each wire segment.…”