Modified dose correction strategy for better pattern contrast

Galler, R.; Melzer, D.; Boettcher, Monika; Krueger, Michael; Suelzle, M.; Wagner, Christian

doi:10.1117/12.863376

Cited by 5 publications

(6 citation statements)

References 4 publications

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“…By decreasing the dimensions of a shape (negative sizing) and proper increasing of the dose, the goal of increasing the DST can be achieved, but only for small shapes [8]. If larger shapes (larger than the range of the short range part of the PPF) are part of a pattern, these shapes should not be treated in the same way.…”

Section: Geometrically Induced Dose Correction Methodsmentioning

confidence: 99%

“…The amount of negative sizing is an input parameter for the GIDC method [8]. The decision, whether a shape is small, depends on the magnitude of the short range part of the PPF.…”

Section: Geometrically Induced Dose Correction Methodsmentioning

confidence: 99%

“…In previous studies we have shown by means of the ePLACE simulation feature [6,7] that the geometrically induced dose correction method provides a possibility to significantly enhance the dose distribution contrast and DST [8]. To demonstrate the achievable improvements, we have performed test exposures.…”

Section: Introductionmentioning

confidence: 96%

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Geometrically induced dose correction: method and performance results

Galler

Choi

Gutsch

et al. 2011

27th European Mask and Lithography Conference

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For current and future semiconductor technology nodes with critical dimensions of 32 nm or below, the e-beam lithography is faced with increasing challenges to achieve a reasonable patterning of structures, especially if a process with a chemically amplified resist is used. The reasons for these limitations are the physical properties of the transfer process used to print a structure onto the resist-coated substrate, which inherently contains an unavoidable blurring of the deposited e-beam energy around the desired shape. This blurring is usually described by a so called process proximity function (PPF) and mostly approximated by a superposition of two or more Gaussian functions. The PPF includes the ebeam blur, electron forward scattering and resist effects (often described altogether by the so called alpha parameter of the PPF [K. Keil et al, "Resolution and total blur: Correlation and focus-dependencies in e-beam lithography," J. Vac. Sci. Technol. B 27, 2722 (2009)]) as well as the backscattering effect (often described by the so called beta parameter of the PPF). When the desired critical dimensions of structures are near or below the alpha parameter of the PPF, depending on their environment it may be just impossible to print the structures because of the vanishing image contrast. The PPF model confirms this well-known behavior but also shows ways and limits for improvements.This paper provides real pattern lithography results -comparing classical and GIDC correction -for exposures done on a Vistec SB3050DW shaped e-beam writer. A performance comparison of the GIDC method and the classical dose correction in terms of data preparation and writing time is presented.

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Section: Geometrically Induced Dose Correction Methodsmentioning

confidence: 99%

“…The amount of negative sizing is an input parameter for the GIDC method [8]. The decision, whether a shape is small, depends on the magnitude of the short range part of the PPF.…”

Section: Geometrically Induced Dose Correction Methodsmentioning

confidence: 99%

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Geometrically induced dose correction: method and performance results

Galler

Choi

Gutsch

et al. 2011

27th European Mask and Lithography Conference

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“…In this work, we focus on solving the fixed dose model-based fracturing problem with rectangular shots, as done in the benchmarking work [16]. Although variable-dose shots [18] and non-rectangular shots [19,20] have been proposed, Elayat et al have concluded that fixed-dose fracturing with rectangular shots is the most viable approach to reduce shot count without significant changes to the mask writing tools [21].…”

Section: Problem Descriptionmentioning

confidence: 99%

Effective model-based mask fracturing for mask cost reduction

Kagalwalla

Gupta

2015

Proceedings of the 52nd Annual Design Automation Conference

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The use of aggressive resolution enhancement techniques like multiple patterning and inverse lithography (ILT) has led to expensive photomasks. Growing mask write time has been a key reason for the cost increase. Moreover, due to scaling, e-beam proximity effects can no longer be ignored. Model-based mask fracturing has emerged as a useful technique to address these critical challenges by allowing overlapping shots and compensating for proximity effects during fracturing itself. However, it has been shown recently that heuristics for model-based mask fracturing can be suboptimal by more than 1.6× on average for ten real ILT shapes, highlighting the need for better heuristics. In this work, we propose a new model-based mask fracturing method that significantly outperforms all the previously reported heuristics. The number of ebeam shots of our method is 23% less than a state-of-the-art prototype version of capability within a commercial EDA tool for ebeam mask shot decomposition (PROTO-EDA) for ten ILT mask shapes. Moreover, our method has an average runtime of less than 1.4s per shape.

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“…e-beam proximity effects in VSB mask writers are simulated during the mask fracturing itself to ensure that the final pattern on the mask accurately matches the intended target. In addition to overlapping shots and proximity effect correction, Galler et al propose to adjust the dose of each shot independently [12]. Jiang and Zakhor propose an algorithm based on matching pursuit to solve this problem [16].…”

Section: Introductionmentioning

confidence: 99%

Benchmarking of Mask Fracturing Heuristics

Chan

Gupta

Han

et al. 2017

IEEE Trans. Comput.-Aided Des. Integr. Circuits Syst.

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Aggressive resolution enhancement techniques such as inverse lithography (ILT) often lead to complex, non-rectilinear mask shapes which make mask writing extremely slow and expensive. To reduce shot count of complex mask shapes, mask writers allow overlapping shots, due to which the problem of fracturing mask shapes with minimum shot count is NP-hard. The need to correct for e-beam proximity effect makes mask fracturing even more challenging. Although a number of fracturing heuristics have been proposed, there has been no systematic study to analyze the quality of their solutions. In this work, we propose a new method to generate benchmarks with known optimal solutions that can be used to evaluate the suboptimality of mask fracturing heuristics. We also propose a method to generate tight upper and lower bounds for actual ILT mask shapes by formulating mask fracturing as an integer linear program and solving it using branch and price. Our results show that a state-of-the-art prototype [version of] capability within a commercial EDA tool for e-beam mask shot decomposition can be suboptimal by as much as 3.7× for generated benchmarks, and by as much as 3.6× for actual ILT shapes.

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Modified dose correction strategy for better pattern contrast

Cited by 5 publications

References 4 publications

Geometrically induced dose correction: method and performance results

Geometrically induced dose correction: method and performance results

Effective model-based mask fracturing for mask cost reduction

Benchmarking of Mask Fracturing Heuristics

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