The impact of 14-nm photomask uncertainties on computational lithography solutions

Sturtevant, John L.; Tejnil, Edita; Lin, Tim; Schultze, Steffen; Buck, Peter; Kalk, Franklin D.; Nakagawa, Kent H.; Guo, Ningqun; Ackmann, Paul; Gans, Fritz; Buergel, Christian

doi:10.1117/12.2013748

Cited by 10 publications

(5 citation statements)

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“…Goal of 3-Segments chop is to best represent proximity error described in eq. [1]. Adjusting length and placement of segments, maximum local similarity with projected real mask is reached as in Fig.…”

Section: Figure3 Workflow Of Contour Extraction and Magnification Cal...mentioning

confidence: 99%

“…This corner-chop then is uniquely determined by the corner step size using eq. [1]~eq. [3] with empirical coefficient 'A' fitted for a particular mask writing condition.…”

Section: Figure3 Workflow Of Contour Extraction and Magnification Cal...mentioning

confidence: 99%

“…At node 28nm and beyond, details in OPC workflow start to become more prominent in order to achieve sub-nm accuracy (1). From mask 3D, resist top-loss effects to contour based wafer metrology, efforts are being made to tackle those issues, which makes OPC more delicate and challenging than ever (2)(3)(4)(5).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mask Corner Chopping Strategy Optimization and Its Impact on Random 2D Logic Pattern OPC Recipe Accuracy

et al. 2014

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At advanced node, mask making details need to be taken into account in OPC in order to achieve the demanded accuracy. Mask corner rounding, which is often emulated by corner chopping of polygons in OPC implementation, is one such an example. In this work, we demonstrated fixed radius corner-chop improves OPC accuracy, however, such an implementation is unable to offer required OPC accuracy, since it still leaves non-negligible ADI error at some random 2D patterns. A 3-segments rule based chop strategy is proposed and tested with which significant simulation accuracy improvement is achieved at little extra computational cost.

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Section: Figure3 Workflow Of Contour Extraction and Magnification Cal...mentioning

confidence: 99%

“…This corner-chop then is uniquely determined by the corner step size using eq. [1]~eq. [3] with empirical coefficient 'A' fitted for a particular mask writing condition.…”

Section: Figure3 Workflow Of Contour Extraction and Magnification Cal...mentioning

confidence: 99%

See 1 more Smart Citation

Mask Corner Chopping Strategy Optimization and Its Impact on Random 2D Logic Pattern OPC Recipe Accuracy

et al. 2014

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“…Further, these mask variations may not be modeled with sufficient accuracy in OPC flows as a consequence of CPU time-saving tradeoffs. For example, mask corner rounding may be approximated by 'corner chipping' and nonlinearity may be lumped into the optical photoresist modeling kernel [3,4].…”

Section: Introductionmentioning

confidence: 99%

Model-based virtual VSB mask writer verification for efficient mask error checking and optimization prior to MDP

et al. 2014

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A methodology is described wherein a calibrated model-based 'Virtual' Variable Shaped Beam (VSB) mask writer process simulator is used to accurately verify complex Optical Proximity Correction (OPC) and Inverse Lithography Technology (ILT) mask designs prior to Mask Data Preparation (MDP) and mask fabrication. This type of verification addresses physical effects which occur in mask writing that may impact lithographic printing fidelity and variability. The work described here is motivated by requirements for extreme accuracy and control of variations for today's most demanding IC products. These extreme demands necessitate careful and detailed analysis of all potential sources of uncompensated error or variation and extreme control of these at each stage of the integrated OPC/ MDP/ Mask/ silicon lithography flow. The important potential sources of variation we focus on here originate on the basis of VSB mask writer physics and other errors inherent in the mask writing process. The deposited electron beam dose distribution may be examined in a manner similar to optical lithography aerial image analysis and image edge log-slope analysis. This approach enables one to catch, grade, and mitigate problems early and thus reduce the likelihood for costly long-loop iterations between OPC, MDP, and wafer fabrication flows. It moreover describes how to detect regions of a layout or mask where hotspots may occur or where the robustness to intrinsic variations may be improved by modification to the OPC, choice of mask technology, or by judicious design of VSB shots and dose assignment.

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“…3,4 One category of such uncertainties in the lithography system can be the photomask shape uncertainty. 5 The mask in lithography is made by e-beam writing, and can be imperfect with significant errors on the critical dimension (CD), which can influence the intra-field CD uniformity on the final wafer. 6 The CD non-uniformity, which is the error between printed mask CD and target CD during the mask making process, can be caused by the e-beam exposure, the e-beam resist process and the etch process.…”

Section: Introductionmentioning

confidence: 99%

Incorporating photomask shape uncertainty in computational lithography

Liu

Erdmann

et al. 2016

SPIE Proceedings

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The lithographic performance of a photomask is sensitive to shape uncertainty caused by manufacturing and measurement errors. This work proposes incorporating the photomask shape uncertainty in computational lithography such as inverse lithography. The shape uncertainty of the photomask is quantitatively modeled as a random ?eld in a level-set method framework. With this, the shape uncertainty can be characterized by several parameters, making it computationally tractable to be incorporated in inverse lithography technique (ILT). Simulations are conducted to show the eâ¬ectiveness of using this method to represent various kinds of shape variations. It is also demonstrated that incorporating the shape variation in ILT can reduce the mask error enhancement factor (MEEF) values of the optimized patterns, and improve the robustness of imaging performance against mask shape ?uctuation

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The impact of 14-nm photomask uncertainties on computational lithography solutions

Cited by 10 publications

References 0 publications

Mask Corner Chopping Strategy Optimization and Its Impact on Random 2D Logic Pattern OPC Recipe Accuracy

Mask Corner Chopping Strategy Optimization and Its Impact on Random 2D Logic Pattern OPC Recipe Accuracy

Model-based virtual VSB mask writer verification for efficient mask error checking and optimization prior to MDP

Incorporating photomask shape uncertainty in computational lithography

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