Source optimization for image fidelity and throughput
Source optimization for image fidelity and throughput
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DOI：
10.1117/1.1794708
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发表时间：
2004-10-01
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影响因子：
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通讯作者：
Granik, Y
中科院分区：
文献类型：
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作者：
Granik, Y
在本研究中，我们首先回顾了现有的源优化方法。缺乏严格的公式激发了对优化目标和约束的讨论。我们强调使用加权和所谓索博列夫规范的重要性。其次，我们将主要的优化问题描述为一组以函数范数积分形式的优化目标，以最大化图像保真度和源平滑度。我们将其简化为非负最小二乘（NNLS）问题，并用标准数值方法求解。第三，我们分析了重要实际案例的解决方案：规则和半规则模式接触孔的交替相移，设计规则为130 ~ 250 nm的两种SRAM电池，以及复杂的半密集接触层模式。最后，我们展示了约束优化如何用于平滑强离轴四极照明，以实现某些选定布局模式的更好图像保真度。(C) 2004光学仪器工程师学会。
In this study we first review existing source optimization methods. Lack of rigorous formulations motivates discussion of the optimization objectives and constraints. We stress the importance of using weighted and so-called Sobolev norms. Second, we state the main optimization problem as a set of the optimization objectives in a form of functional norm integrals to maximize image fidelity and source smoothness. We reduce this to a non-negative least square (NNLS) problem, which is solved by standard numerical methods. Third, we analyze solutions for important practical cases: alternating phase shifting applied to regular and semiregular pattern of contact holes, two types of SRAM cells with design rules from 130 to 250 nm, and a complex semidense contact layer pattern. Finally, we show how constraint optimization can be used to smooth strong off-axis quadrupole illuminations to achieve better image fidelity for some selected layout patterns. (C) 2004 Society of Photo-Optical Instrumentation Engineers.