Simulating the effects of pattern density gradients on electron-beam projection lithography pattern transfer distortions

Reu, Phillip L.; Engelstad, Roxann L.; Lovell, Edward G.; Magg, Chris; Lercel, Michael J.; Mackay, R. Scott

doi:10.1116/1.1409387

Cited by 9 publications

(4 citation statements)

References 2 publications

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“…[13] The Sematech funded study also confirmed University of Wisconsin modeling results that pattern density gradients have the worst impact on IP. [15] For example, a subfield that was half-filled with a dense pattern (the other half being unpatterned) caused a large image placement distortion along the line of highest pattern density gradient. Unlike simple magnification corrections, this effect is not easily corrrectable and most likely sets the upper bound on allowable membrane stress.…”

Section: Pattern and Materials Requirementsmentioning

confidence: 99%

Analysis of critical parameters for EPL mask fabrication

Lercel¹

2002

Emerging Lithographic Technologies VI

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Electron projection lithography (EPL) requires mask formats that are significantly different from those used in traditional optical lithography. These masks must consist of a thin membrane that is either patterned with transmissive perforations for stencil masks or patterned with a scatterer layer to form a continuous membrane mask. In this paper, the critical requirements for fabrication of EPL masks are discussed. Challenges for mask blank fabrication, image size uniformity, image placement accuracy, and defect control are presented with examples from mask fabrication. The impact of these parameters on EPL mask cost is then discussed. The mask cost is compared for different critical device levels and for different chip sizes. The influence of mask parameters and need for complementary masks drives higher mask costs for certain device levels. By examining the factors influencing mask cost for certain levels, the areas of mask technology that are most critical to controlling mask cost can be identified.

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Section: Pattern and Materials Requirementsmentioning

confidence: 99%

Analysis of critical parameters for EPL mask fabrication

Lercel¹

2002

Emerging Lithographic Technologies VI

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“…The three main factors that contribute to image placement distortions are: shape of the mask, accuracy of the e-beam writer, and stress of the materials. Past publications have shown that there is the ability to correct image placement distortions during the exposure of the mask on the wafer [1,2]. Although image placement distortions can be corrected using these techniques, they cannot completely correct all of the distortions and the stress of the membranes still needs to be extremely low to meet the strict image placement specification.…”

Section: Introductionmentioning

confidence: 98%

Image Placement Distortions in EPL Masks

Thiel¹,

Kindt²,

Lawliss³

2002

SPIE Proceedings

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Electron projection lithography (EPL) is a promising candidate for the next generation lithography choice. There are several advantages to EPL, such as a large depth of focus and a lower relative mask cost. Significant challenges also face this technology, including the limitation of the membrane format of the mask. One of the obstacles with the membrane format is image placement distortions, which can be very sensitive to the stress of the membrane as well as the pattern density. This paper studies how the stress of various types of films effects image placement distortions, as well as examines the effect of final mask cleans on image placement distortions.

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“…[1][2][3][4] In this study, FE structural models simulated productionlike EPL masks fabricated from 200-mm-diam silicon wafers with two 55 mmϫ 132 mm membrane areas separated by a 10-mm-wide major strut. For this target node, the development of a lowdistortion mask is essential.…”

Section: Introductionmentioning

confidence: 99%

Assessment of image placement errors induced in electron projection lithography masks by chucking

Chang

Engelstad

Lovell

et al. 2004

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Electron projection lithography (EPL) is under active development, with potential applications at the sub 65 nm nodes. In order to meet the stringent error budgets in this regime, image placement (IP) errors induced by chucking the mask during e-beam patterning, metrology, and exposure must be characterized and minimized. The focus of this study is to assess the distortions induced in 200-mm-diam EPL stencil masks by chucking during e-beam patterning and EPL exposure. High-throughput test masks ͑with 3.39 mm square membrane windows͒ were evaluated, to assess IP errors throughout a typical mask process flow. Finite element structural models were developed to simulate the response of the test mask during each processing step. Finally, the results of the analysis were used to identify and characterize the sources of IP errors.

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Simulating the effects of pattern density gradients on electron-beam projection lithography pattern transfer distortions

Cited by 9 publications

References 2 publications

Analysis of critical parameters for EPL mask fabrication

Analysis of critical parameters for EPL mask fabrication

Image Placement Distortions in EPL Masks

Assessment of image placement errors induced in electron projection lithography masks by chucking

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