Mixed-Cell-Height Placement With Complex Minimum-Implant-Area Constraints
Mixed-Cell-Height Placement With Complex Minimum-Implant-Area Constraints
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DOI：
10.1109/tcad.2021.3133855
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发表时间：
2022-11
影响因子：
2.9
通讯作者：
Jianli Chen;Zhifeng Lin;Yanyue Xie;Wen-xing Zhu;Yao-Wen Chang
中科院分区：
文献类型：
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作者：
Jianli Chen;Zhifeng Lin;Yanyue Xie;Wen-xing Zhu;Yao-Wen Chang
混合蜂窝高度标准蜂窝普遍用于先进技术中，以在时序、功率和可达性之间实现更好的设计权衡。随着特征尺寸的减小，具有多个阈值电压的电池的放置可能违反复杂的最小植入面积（MIA）层规则，这是由于图像化技术的限制而产生的。现有作品仅在合法化阶段考虑混合单元高度安置问题，或在详细安置阶段处理MIA约束。在本文中，我们在两个主要阶段解决MIA约束下的混合细胞高度安置问题：1)后全局安置（Post-GP）和2)MIA感知合法化。在后gp阶段，我们首先提出了一个连续可微的代价函数来解决Vdd/Vss对齐约束，并动态地向mia违规单元添加加权伪网络。然后，我们提出了一种基于给定全局布局结果的最接近优化方法，同时考虑Vdd/Vss对齐约束、MIA约束、单元分布、单元位移和总无线长度。在mia感知合法化阶段，我们开发了一种基于图的方法来聚集特定阈值电压的细胞，并应用基于条带包装的二元线性规划来重塑细胞。然后，我们提出了一种基于匹配的技术来解决内部MIA违规并减少填充物的插入。在此基础上，我们将行间mia感知的合法化化为一个二次规划问题，并利用基于模的矩阵分裂迭代方法有效地求解了该问题。最后，进行mia感知的单元分配和细化，进一步改进结果。实验结果表明，在不增加任何额外面积开销的情况下，该算法的最终总波长仍比现有算法短5.4%。
Mixed-cell-height standard cells are prevailingly used in advanced technologies to achieve better design tradeoffs among timing, power, and routability. As feature size decreases, the placement of cells with multiple threshold voltages may violate the complex minimum-implant-area (MIA) layer rule arising from the limitations of patterning technologies. Existing works consider the mixed-cell-height placement problem only during legalization or handle the MIA constraints during detailed placement. In this article, we address the mixed-cell-height placement problem with MIA constraints in two major stages: 1) post-global placement (Post-GP) and 2) MIA-aware legalization. In the Post-GP stage, we first present a continuous and differentiable cost function to address the Vdd/Vss alignment constraints and add weighted pseudonets to MIA-violation cells dynamically. Then, we propose a proximal optimization method based on the given global placement result to simultaneously consider Vdd/Vss alignment constraints, MIA constraints, cell distribution, cell displacement, and total wirelength. In the MIA-aware legalization stage, we develop a graph-based method to cluster cells of specific threshold voltages and apply a strip-packing-based binary linear programming to reshape cells. Then, we propose a matching-based technique to resolve intrarow MIA violations and reduce filler insertion. Furthermore, we formulate inter-row MIA-aware legalization as a quadratic programming problem, which is efficiently solved by a modulus-based matrix splitting iteration method. Finally, MIA-aware cell allocation and refinement are performed to further improve the result. Experimental results show that without any extra area overhead, our algorithm still can achieve 5.4% shorter final total wirelength than the state-of-the-art work.