Writing strategy for a high-throughput SCALPEL system

Stanton, Stuart T.; Liddle, J. Alexander; Felker, Joseph A.; Waskiewicz, W. K.; Harriott, L. R.

doi:10.1117/12.351091

Cited by 9 publications

(4 citation statements)

References 12 publications

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“…the aperture angle a, 2. the main-field vector m (i.e. the off-axis distance ofthe sub-field center in the wafer plane), 3. the sub-field vector s (i.e.…”

Section: Electron Optical Simulation Methodsmentioning

confidence: 99%

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Electron optical analysis of SCALPEL writing strategy

Zhu¹,

Munro²,

Liu³

et al. 1999

SPIE Proceedings

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In SCALPEL, the maximum projected area of the electron optical sub-field, though large by electron optical standards, is limited by aberrations of the projection optics. The effective exposure region can be increased by electronically scanning the illumination off-axis, in a direction orthogonal to the mechanical motion of the mask and wafer stages.' Even though the aberrations associated with the scan are minimized by applying dynamic corrections, the residual aberrations may still increase with increasing off-axis scan distance. Thus the image quality may vary during dose accumulation in each pixel.Our previous simulation method has been extended to consider the writing strategy, including scanning the sub-field over a pixel, and eliminating the mask struts and the non-patterned regions (skirts) at the wafer plane. We have examined two variations of writing strategy, for a column with demagnification m: (1) The case where the mask stage velocity is exactly m times the wafer stage velocity, and (2) The case where the mask stage velocity is increased so that the mask and wafer pauerns remain in synchronism with each other, after removing the unpatterned areas of the mask from the image. In case (1), an additional deflection is required to eliminate the struts and skirts in the mask from the printed image. This deflection increases with time, as the mask and wafer patterns get progressively out of synchronism. Case (2) eliminates this effect. We compare these two cases, and show that case (2) provides significantly improved fabricated pattern quality.

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“…the aperture angle a, 2. the main-field vector m (i.e. the off-axis distance ofthe sub-field center in the wafer plane), 3. the sub-field vector s (i.e.…”

Section: Electron Optical Simulation Methodsmentioning

confidence: 99%

“…along the +x direction in one stripe and the -x direction in the next stripe. 3 The beam center thus traces out a square wave path on the wafer surface. During the time period tof one pair of scans, the wafer should move a distance 2b' in the y direction.…”

Section: Scan Pattern In the Wafer Planementioning

confidence: 99%

Electron optical analysis of SCALPEL writing strategy

Zhu¹,

Munro²,

Liu³

et al. 1999

SPIE Proceedings

Self Cite

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“…But this requires illumination of the mask, that falls off over a certain distance in order to accumulate the correct dose despite the fact that the overlap area is exposed twice. Along the longitudinal direction of the stripes, this is realized by using a sub field that is not exactly square, but has slightly tapered ends [6] resulting in "hexagon-shaped" electron beams. In the scanning direction, this can be done using so-called reticle masking blades similar to those used in some light optical lithography machines.…”

Section: Writing Strategymentioning

confidence: 99%

Design of an electron projection system with slider lenses and multiple beams

Moonen

Leunissen²,

Jager

et al. 2002

Emerging Lithographic Technologies VI

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The commercial applicability of electron beam projection lithography systems may be limited at high resolution because of low throughput. The main limitations to the throughput are:• Beam current. The Coulomb interaction between electrons result in an image blur. Therefore less beam current can be allowed at higher resolution, impacting the illumination time of the wafer. • Exposure field size. Early attempts to improve throughput with "full chip" electron beam projection systems failed, because the systems suffered from large off-axis aberrations of the electron optics, which severely restricted the useful field size. This has impact on the overhead time.A new type of projection optics will be proposed in this paper to overcome both limits. A slider lens is proposed that allows an effective field that is much larger than schemes proposed by SCALPEL and PREVAIL. The full width of the die can be exposed without mechanical scanning by sliding the beam through the slit-like bore of the lens. Locally, at the beam position, a "round"-lens field is created with a combination of a rectangular magnetic field and quadrupoles that are positioned inside the lens. A die can now be exposed during a single mechanical scan as in state-of-the-art light optical tools.The total beam current can be improved without impact on the Coulomb interaction blur by combining several beams in a single lithography system if these beams do not interfere with each other. Several optical layouts have been proposed that combine up to 5 beams in a projection system consisting of a doublet of slider lenses. This type of projection optics has a potential throughput of 50 WPH (300 mm) at 45 nm with a resist sensitivity of 6 µC/cm 2 .

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“…10 By using a robust seam-blending technique, the effect of pattern placement errors on CD is weak and decoupled from dose control. Defocus introduces negligible blur and experiences essentially zero coupling to the dose latitude available on the system, unlike the case of diffraction-limited optics.…”

Section: Introductionmentioning

confidence: 99%

Critical tool performance analysis for SCALPEL extensibility

Stanton¹,

Liddle²,

Waskiewicz³

et al. 2000

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

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Electron and ion optical design software for integrated circuit manufacturing equipmentAn important feature of any advanced lithography technology is its cost-effective extension over several device generations beyond its introduction. Since SCALPEL is an electron imaging system with resolution not limited by diffraction, a unique extensibility analysis is needed to establish development pathways for the evolution of SCALPEL to the 50 nm generation and beyond. A combination of modest progress in four performance areas-effective optical field width, aberrations, acceptable dose latitude, and stage performance-will allow SCALPEL to maintain good throughput over several lithography generations without aggressive optical design scaling.

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Writing strategy for a high-throughput SCALPEL system

Cited by 9 publications

References 12 publications

Electron optical analysis of SCALPEL writing strategy

Electron optical analysis of SCALPEL writing strategy

Design of an electron projection system with slider lenses and multiple beams

Critical tool performance analysis for SCALPEL extensibility

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