Nonspecular scattering from extreme ultraviolet multilayer coatings

Stearns, D. G.; Gullikson, Eric M.

doi:10.1016/s0921-4526(99)01897-9

Cited by 30 publications

(14 citation statements)

References 25 publications

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“…Masks used in EUV lithography are reflective and are rendered so through the deposition of a multilayer coating typically comprised of 40 or more bilayers [11]. If one starts with knowledge of the uncoated substrate surface, multilayer growth models can be used [12,13] to predict the coating properties throughout the stack. From the calculated coating properties, rigorous electromagnetic field modeling could be used to calculate the electric field reflected from the mask [14][15][16].…”

Section: Modeling Methodologymentioning

confidence: 99%

System-level line-edge roughness limits in extreme ultraviolet lithography

Naulleau¹,

Niakoula²,

Zhang³

2008

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

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As critical dimensions shrink, line edge and width roughness (LER and LWR) become of increasing concern. Traditionally LER is viewed as a resist-limited effect; however, as critical dimensions shrink and LER requirements become proportionally more stringent, system-level effects begin to play an important role. Recent advanced EUV resist testing results have demonstrated lower bounds on achievable LER at the level of approximately 2 to 3 nm. Here we use modeling to demonstrate that a significant portion of this low bound may in fact be do to system-level effects and in particular the mask. Of concern are both LER on the mask as well as roughness of the multilayer reflector. Modeling also shows roughness (flare) in the projection optics not to be of concern.

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Section: Modeling Methodologymentioning

confidence: 99%

System-level line-edge roughness limits in extreme ultraviolet lithography

Naulleau¹,

Niakoula²,

Zhang³

2008

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

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“…[1][2][3][4][5][6] In this article, we discuss results for the WSi 2 / Si bilayer system, which has been the system chosen in recent efforts to produce x-ray Laue focusing lenses with nanometer-scale line or point focus. Many of these devices require reduced interface roughness in order to approach their optimum theoretical performance.…”

Section: Introductionmentioning

confidence: 99%

Interface roughness evolution in sputtered WSi2∕Si multilayers

Wang

Zhou

et al. 2007

Journal of Applied Physics

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We report on the growth of WSi 2 and Si amorphous thin films by dc magnetron sputtering. In situ synchrotron x-ray scattering with high temporal resolution has been employed to probe the surface and interface roughness during film deposition. It is found that the WSi 2 / Si multilayer surface alternately roughens and smoothes during deposition; while the Si layer roughness monotonically, the WSi 2 layer is observed to smooth out when deposited on an initially rough surface. Subsequent deposition of the next layer effectively freezes in the surface morphology of the previous layer in each case. Energetic neutrals and ions assisting the growth may play a role in inducing this pronounced alternating pattern in the roughness.

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“…It is known that the nanotopography, and thus the nanoroughness, of any interface in the coating is a result of a combination of: (i) the underlying interface topography replicated through the film and (ii) additional intrinsic film roughness caused by the statistical noise of incoming particles [33][34][35]. Replication usually occurs at lower spatial frequencies, whereas the intrinsic roughness of the coatings often dominates at higher spatial frequencies.…”

Section: Roughness Analysismentioning

confidence: 99%