The MEEF NILS divergence for low k1 lithography

Schenker, Richard E.; Cheng, Wen‐Hao; Allen, Gary

doi:10.1117/12.742273

Cited by 7 publications

(2 citation statements)

References 7 publications

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“…15 has been questioned. 12 Although Eq. 15 indicates that wafer linewidth variations induced by reticle linewidth variations are inversely proportional to the image log-slope, we do not include Eq.…”

Section: Shown Inmentioning

confidence: 98%

Proposal for determining exposure latitude requirements

Levinson

Koenig³

et al. 2008

Optical Microlithography XXI

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To determine the magnitude of the exposure latitude required for a process to be manufacturable, additional factors are considered that have a similar relationship between linewidth variation and image log-slope. Such parameters include resist thickness, flare, post-exposure bake temperature, and line-edge roughness. To obtain consistency between theory and experiment it is necessary to use the resist-edge log-slope generalization of image log-slope. Inclusion of these additional factors increases the required exposure latitude several times more than would be considered necessary from exposure tool dose control alone.

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Section: Shown Inmentioning

confidence: 98%

Proposal for determining exposure latitude requirements

Levinson

Koenig³

et al. 2008

Optical Microlithography XXI

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“…(MSDz is also well-defined, but not considered in this paper.) MSDx motions degrade the contrast of vertical lines in a manner virtually identical to resist blur, and so a similar contrast loss factor can be calculated as CMSDx = exp[ -2 ( MSDx / P ) 2 ] , (10) which only applies to vertical lines. An analogous equation connects the contrast of horizontal lines with MSDy .…”

Section: Image Fading From Scanningmentioning

confidence: 99%

Image contrast metrology for EUV lithography

Brunner¹,

Truffert²,

Ausschnitt³

et al. 2022

International Conference on Extreme Ultraviolet Lithography 2022

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Image contrast is an important measure of image quality, especially for EUV lithography where high contrast can mitigate stochastic process fluctuations1 such as Line-Edge Roughness (LER), Line Width Roughness (LWR), Local CD Uniformity (LCDU) and stochastic defects. In this paper, several aspects of image contrast for EUV lithography are discussed. We will look at some of the fundamental mechanisms which degrade image contrast, including resist blur from acid diffusion. We assume the imaging of dense line/space images with k1<0.5. This assumption guarantees that the image is a simple sinusoid, and implies that the exposure latitude is proportional to the image contrast. We then consider various methods to experimentally measure image contrast. The classic measure would be to measure the exposure latitude from a Focus/Exposure Matrix (FEM) wafer. The exposure latitude is generally giving a contrast measure which is averaged over some portion of the wafer. In this paper, we propose the use of MEEF (Mask Error Enhancement Factor) targets to track contrast at specific locations on the wafer. In principle, one could measure many points across the image field (or even across the whole wafer) to map out the spatial variation of contrast, i.e. a contrast map. The paper includes experimental contrast measurements that relate to stage fading, source shape and resist blur from different processes. We will also briefly look at fading from the Pole-to-Pole image shift, and how to mitigate this with a novel exposure method called Dual Monopole.

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