Optimizing style options for subresolution assist features

Liebmann, Lars W.; Bruce, James A.; Chu, W. H.; Cross, Michael; Graur, Ioana; Krueger, Joshua J.; Leipold, William C.; Mansfield, Scott; McGuire, Anne; Sundling, D.L.

doi:10.1117/12.435690

Cited by 21 publications

(13 citation statements)

References 2 publications

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“…This portion of the SRAF will be the most likely to print, and thus it determines the minimum dose that can be used with this SRAF option. Other styles that lead to a locally large SRAF are given in [2]. The more aggressive the style options chosen to maximize the SRAF coverage, the higher the dose required to avoid printing portions of the SRAF.…”

Section: Sraf Designmentioning

confidence: 99%

<title>Model-based OPC for sub-resolution assist feature enhanced layouts</title>

et al. 2002

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Sub-resolution assist features (SRAF) have been demonstrated to provide significant process window improvement when used in combination with off-axis illumination (OAI) and attenuated phase shifted mask enhanced lithography ("attPSM"). While some through pitch linewidth variations can be reduced through the use of SRAF, the main goal is to improve common process window, leaving the task of linewidth control to conventional optical proximity correction (OPC). OPC in combination with SRAF is also required to address two-dimensional patterning infidelities such as corner rounding and line end shortening, for which SRAF do not provide adequate correction. Finally, OPC will be used as a means of recovering process window that may be lost in layout situations that result in poor SRAF coverage. With an industry wide migration from rules-based OPC to iterative, model-based solutions, the integration of inherently rules based SRAF generation and model-based OPC has to be investigated.

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Section: Sraf Designmentioning

confidence: 99%

<title>Model-based OPC for sub-resolution assist feature enhanced layouts</title>

et al. 2002

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“…Once run, a process variability band (PV Band) metric will be defined as the XOR of all the contours. The width of this PV Band normalized to the total layout area is a measure of process window [11,12]. • Runtime -This is defined as the time taken between the acceptance of a target layout and the production of a final mask solution.…”

Section: A Problem Statementmentioning

confidence: 99%

“…We note that 1x metal contains the most challenging shapes for printing due to high density and bi-directionality of wiring. We allow a flexibility of +/-15nm on the edge placement error (EPE), which allows contestants sufficient amount of flexibility in finding a mask optimization solution which minimizes the process variability (PV) bands [11,12,14], while still reasonably matching the target shape. PV bands are a measure of the robustness of printing of a contour and denote the variability in the location of the contour across the lithographic process window.…”

Section: Introductionmentioning

confidence: 99%

“…This is the process of pre-compensating for the distortions induced by the lithographic process by modifying the mask shapes. It includes one or more of the techniques such as insertion of sub-resolution assist features (SRAF) [12], optical proximity correction (OPC) [4,6,7], process window OPC (PWOPC) [13] and inverse lithographic techniques (ILT) [11]. Since the sub-100nm nodes, mask optimization has become vital to ensuring high lithographic yield at the current 193nm lithography node.…”

Section: Introductionmentioning

confidence: 99%

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ICCAD-2013 CAD contest in mask optimization and benchmark suite

Banerjee¹,

Li²,

Nassif³

2013

2013 IEEE/ACM International Conference on Computer-Aided Design (ICCAD)

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Optical microlithography is the technique of printing a set of shapes on a wafer using light transmitted through a template called a mask. Repeatedly printing and stacking such shapes on top of each other to build electrical circuits allows us to manufacture chips in high volume. However this technique has now reached its fundamental physical limits of resolution. Current 193nm wavelength light is no longer sufficient to reliably transfer patterns which are now in the sub-100nm dimensional range. This has led to increased research in optimizing lithographic masks to pre-compensate for distortions introduced by the lithographic process. This is called mask optimization. In this contest, students are provided with a sample lithographic model which simulates the transfer of a mask pattern on to wafer. The mask is assumed to be a pixelated template, where every pixel can be turned on or off, to indicate where light passes through, or is blocked. Contestants are also provided with models to predict the robustness of their pattern i.e. how much variability is in the transferred pattern. Given these tools, the objective is to minimize the variability in the wafer image, as measured by process variability (PV) bands. This is subject to the constraints of runtime and satisfying pattern fidelity i.e. the transferred pattern should resemble the target pattern. Benchmarks are provided in the form of collections of geometric shapes, each of which provides a challenge in printing at sub-wavelength.

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“…Increasing use of OPC [1][2][3][4][5][6] is required to enable the extension of optical lithography to deep-subwavelength printing while maintaining feature fidelity and linewidth accuracy. Extending 248nm lithography to its limits will entail the use of complex model-based OPC.…”

Section: Introductionmentioning

confidence: 99%

100-nm OPC mask patterning using raster-scan 50-kV pattern generation technology

Abboud¹,

Baik²,

Chakarian³

et al. 2002

21st Annual BACUS Symposium on Photomask Technology

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The complexity of photomasks is rapidly increasing as semiconductor devices are scaled down and optical proximity correction (OPC) becomes commonplace. Raster scan architectures are well suited to the challenge of maintaining mask throughput despite these trends. Electron-beam techniques have the resolution to support OPC requirements into the foreseeable future. The MEBES ® eXara mask pattern generator combines the resolution of a finely focused electron probe with the productivity and accuracy of Raster Graybeam patterning. Features below 100nm can be created, and OPC designs are produced with consistent fidelity. Write time is independent of resist sensitivity, allowing high-dose processes to be extended, and relaxing sensitivity constraints on advanced chemically amplified resists. The system is designed for the production of 100nm photomasks, and will support the development of 70nm masks.

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Optimizing style options for subresolution assist features

Cited by 21 publications

References 2 publications

<title>Model-based OPC for sub-resolution assist feature enhanced layouts</title>

<title>Model-based OPC for sub-resolution assist feature enhanced layouts</title>

ICCAD-2013 CAD contest in mask optimization and benchmark suite

100-nm OPC mask patterning using raster-scan 50-kV pattern generation technology

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