Mr. Ulf Weidenmueller Profile

Ulf Weidenmueller

Manager Support Ctr at Vistec Electron Beam GmbH

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Author

Publications (20)

Proceedings Article | 9 April 2024 Poster + Paper

Impact of e-beam lithography and data preparation optimization on optical performance of integrated photonic waveguides

M. Greul, K. Edelmann, S. Fasold, J. Hartbaum, E. Linn, I. Stolberg, U. Weidenmueller

Proceedings Volume 12956, 129560N (2024) https://doi.org/10.1117/12.3010355

KEYWORDS: Waveguides, Electron beam lithography, Design, Integrated photonics, Fabrication, Silicon photonics, Photonics systems

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Proceedings Article | 21 November 2023 Presentation + Paper

Efficient patterning approaches for non-Manhattan layouts by using variable shaped beam systems

Ines Stolberg, Eike Linn, Ulf Weidenmueller, Matthias Slodowski

Proceedings Volume 12751, 127510K (2023) https://doi.org/10.1117/12.2688360

KEYWORDS: Electron beam lithography, Vestigial sideband modulation, Photonics, Lithography, Industrial applications, Reproducibility, Optics manufacturing, Optical gratings, Manufacturing, Geometrical optics

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SPIE Journal Paper | 12 July 2023

Efficient exposure of non-Manhattan layouts for optical applications using variable shaped beam lithography

Eike Linn, Stefan Fasold, Ines Stolberg, Ulf Weidenmueller

JM3, Vol. 22, Issue 04, 041406, (July 2023) https://doi.org/10.1117/12.10.1117/1.JMM.22.4.041406

KEYWORDS: Optical gratings, Axicons, Air contamination, Vestigial sideband modulation, Scanning electron microscopy, Design and modelling, Optical components, Edge roughness, Electron beams, Electron beam lithography

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Proceedings Article | 1 May 2023 Presentation + Paper

Efficient exposure of non-Manhattan layouts using Vistec’s shaped beam systems

E. Linn, S. Fasold, R. Galler, S. Kuefner, I. Stolberg, M. Suelzle, U. Weidenmueller

Proceedings Volume 12497, 1249704 (2023) https://doi.org/10.1117/12.2656928

KEYWORDS: Edge roughness, Optical gratings, Axicons, Electron beam lithography, Optical components, Lithography, Electron beams, Silicon photonics, Scanning electron microscopy, Electron beam direct write lithography

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Proceedings Article | 27 February 2015 Paper

Low-crosstalk fabrication-insensitive echelle grating multiplexers and passives for the silicon photonics toolbox

Corrado Sciancalepore, Richard Lycett, Jacques Dallery, Sebastien Pauliac, Karim Hassan, Julie Harduin, Hélène Duprez, Ulf Weidenmueller, Dominic F. Gallagher, Sylvie Menezo, Badhise Ben-Bakir

Proceedings Volume 9365, 936508 (2015) https://doi.org/10.1117/12.2075335

KEYWORDS: Waveguides, Diffraction gratings, Brain-machine interfaces, Optical design, Fiber couplers, Semiconducting wafers, Multiplexers, Silicon, Interferometers, Dispersion

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Proceedings Article | 17 April 2012 Paper

Pointwise process proximity function calibration: PPFexplorer application results

M. Krueger, M. Banasch, R. Galler, D. Melzer, L. Ramos, M. Suelzle, U. Weidenmueller, U. Zeitner

Proceedings Volume 8352, 83520I (2012) https://doi.org/10.1117/12.920568

KEYWORDS: Calibration, Sensors, Photoresist processing, Electron beam lithography, Cadmium, Scanning electron microscopy, Critical dimension metrology, Photomasks, Target detection, Electron beams

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The semiconductor industry and mask shops spend great efforts in order to keep pace with the requirements on pattern fidelity of the ITRS lithography roadmap. Even for e-beam lithography - often referred to as technology with "unlimited" resolution - the challenges increase with shrinking feature sizes in combination with applicable resist processes. The pattern fidelity, specifically CD control, is crucial for the application of e-beam lithography. One aspect in CD control is the intrinsic proximity effect of the electron beam. This together with other contributions like influences from resist process or beam generation which are summarized altogether under the term process proximity effect have to be corrected. An accurate e-beam process proximity effect correction is therefore a key component of e-beam lithography. Some process proximity effect correction algorithms provide not only accurate correction for the process proximity effect induced pattern deformation but also optimize pattern contrast by adjusting geometry and dose simultaneously. However, the quality of the process proximity effect correction is limited by the calibration accuracy of the used model, i.e., the accuracy of the utilized process proximity function (PPF). In a previous paper [R. Galler et al, "PPF - Explorer: Pointwise Proximity Function calibration using a new radialsymmetric calibration structure", BACUS 2011] the PPF-explorer - a new experimental method for pointwise process proximity function calibration - was introduced and some first promising calibration results were shown. This paper presents the progress of the PPFexplorer proximity function calibration. This progress, among others, comprises automatic generation of calibration patterns, including pre-correction with respect to a rough forecast of the process proximity function to be calibrated. This pre-correction approach significantly reduces the number of necessary calibration structures and the number of measurement sites, without sacrificing calibration accuracy. On the contrary, the pre-correction has positive impact on the calibration quality, since it allows unifying the pattern contrast at the measurement sites, which reduces the SEM measurement induced error. We present the results of a PPFexplorer calibration with special focus on minimizing the number of measurement sites. The results show that the PPFexplorer method can help to improve the proximity effect model calibration with controllable efforts.

Proceedings Article | 21 March 2012 Paper

Optimization of MSB for future technology nodes

Hans-Joachim Doering, Thomas Elster, Matthias Klein, Joachim Heinitz, Marc Schneider, Ulf Weidenmüller, Matthias Slodowski, Ines Stolberg, Wolfgang Dorl

Proceedings Volume 8323, 83232D (2012) https://doi.org/10.1117/12.916394

KEYWORDS: Line width roughness, Stochastic processes, Monte Carlo methods, Distortion, Beam shaping, Photomasks, Optical simulations, Vestigial sideband modulation, Electronics, Error analysis

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In the ITRS roadmap [1] increasingly long mask write and cycle time is explicitly addressed as a difficult challenge in mask fabrication for the 16nm technology node and beyond. Write time reduction demands have to be seen in relation to corresponding performance parameters like Line Width Roughness (LWR), resolution, placement as well as CD Uniformity. The previously presented Multi Shaped Beam (MSB) approach [2, 3] is considered a potential solution for high throughput mask write application. In order to fully adapt the MSB concept to future industry's requirements specific optimizations are planned. The key element for achieving write time reduction is a higher probe current at the target, which can be obtained by increasing the number of beamlets as well as applying a higher current density. In the present paper the approach of a 256 beamlet MSB design will be discussed. For a given image field size along with a beamlet number increase both beamlet pitch and size have to be optimized. Out of previous investigations, one finding was that by changing the demagnification after the beam forming section of the MSB column the overall performance can be optimized. Based on first electron-optical simulations for a new final lens a larger demagnification turned out to be advantageous. Stochastic beam blur simulation results for the MSB reduction optics will be presented. During the exposure of a pattern layout the number of used beams, their shape and their distribution within the image field varies, which can lead to space charge distortion effects. In regard to this MSB simulation results obtained for an image field of approximately 10x10ìm² will be presented. For the 256 beamlet MSB design and resist sensitivities of 20μC/cm², 40μC/cm² and 100μC/cm² write time and LWR simulations have been performed. For MSB pattern data fracturing an optimized algorithm has been used, which increased the beamlet utilization factor (indicates the mean number of beamlets which are used per multi-shot). Finally an update with regard to the required changes of the data path architecture for the 256 beamlet MSB approach will be given. Data integrity as an important aspect of the production worthiness of such a systems will be discussed specifically.

Proceedings Article | 14 October 2011 Paper

PPF-Explorer: pointwise proximity function calibration using a new radial symmetric calibration structure

R. Galler, M. Krueger, D. Melzer, L. Ramos, M. Suelzle, U. Weidenmueller

Proceedings Volume 8166, 81660P (2011) https://doi.org/10.1117/12.896759

KEYWORDS: Calibration, Monte Carlo methods, Electron beam lithography, Lithography, Photoresist processing, Cadmium sulfide, Scattering, Point spread functions, Critical dimension metrology, Semiconductors

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Lithographic patterning encounters growing challenges to meet the requirements of current and future semiconductor technology nodes. Even e-beam lithography is challenged due to the physical characteristic of the whole transfer process including the e-beam blur, electron scattering, and resist effects. These effects cause an unavoidable blurring of the exposed shapes and are often described as process proximity effect. Besides the correction of this process proximity effect pattern contrast and process window for the lithography step have to be regarded. There are promising approaches for contrast enhancing proximity effect correction concepts. To enable a stable patterning great efforts have to be put into decreasing the errors of all involved technologies. The blurring resulting from the transfer process is usually described by a so-called process proximity function (PPF) and mostly approximated by a superposition of two or more Gaussian functions. All algorithms for proximity effect correction use that PPF to perform their correction. Thus, an accurate determination of that PPF contributes to reducing the error budget of the proximity effect correction scheme. Several methods for PPF calibration were introduced in the past. Some are based on modelling the transfer process and performing Monte Carlo simulations. Another common approach is to design and expose calibration patterns, measure the resulting CDs, and obtain the process proximity function as the result of a simulation based parameter fitting to a model function such as a sum of Gaussian functions. In order to respect the increased accuracy requirements an even more accurate description of the PPF is expected. This paper describes the newly developed PPF-explorer method for the calibration of a pointwise proximity function as a complementary technique, which is based on the exposure and evaluation of new calibration layouts. Following the common assumption that a process proximity function is radial-symmetric, we developed radial-symmetric calibration layouts.

SPIE Journal Paper | 1 October 2011

Fast characterization of line end shortening and application of novel correction algorithms in e-beam direct write

Martin Freitag, Kang-Hoon Choi, Manuela Gutsch, Christoph Hohle, Reinhard Galler, Michael Krüger, Ulf Weidenmüller

JM3, Vol. 10, Issue 04, 043012, (October 2011) https://doi.org/10.1117/12.10.1117/1.3659145

KEYWORDS: Cadmium, Semiconducting wafers, Computer simulations, Electron beams, Detection and tracking algorithms, Electron beam lithography, Point spread functions, Model-based design, Modulation, Nanoelectronics

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Proceedings Article | 4 April 2011 Paper

Fast characterization of line-end shortening and application of novel correction algorithms in e-beam direct write

Martin Freitag, Kang-Hoon Choi, Manuela Gutsch, Christoph Hohle, Reinhard Galler, Michael Krüger, Ulf Weidenmueller

Proceedings Volume 7970, 79701C (2011) https://doi.org/10.1117/12.879582

KEYWORDS: Cadmium sulfide, Computer simulations, Semiconducting wafers, Electron beam lithography, Electron beams, Detection and tracking algorithms, Point spread functions, Electron beam direct write lithography, Modulation, Nanoelectronics

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Proceedings Article | 2 April 2011 Paper

MSB for ILT masks

Juergen Gramss, Ulf Weidenmueller, Arnd Stoeckel, Renate Jaritz, Hans-Joachim Doering, Monika Boettcher

Proceedings Volume 7985, 798504 (2011) https://doi.org/10.1117/12.896883

KEYWORDS: Photomasks, Vestigial sideband modulation, Beam shaping, Lithography, Optical simulations, Logic devices, Optical proximity correction, Standards development, Statistical analysis, Scanning electron microscopy

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Proceedings Article | 2 April 2011 Paper

Geometrically induced dose correction: method and performance results

R. Galler, K.-H. Choi, M. Gutsch, C. Hohle, M. Krueger, L. Ramos, M. Suelzle, U. Weidenmueller

Proceedings Volume 7985, 79850S (2011) https://doi.org/10.1117/12.895205

KEYWORDS: Electron beam lithography, Line edge roughness, Cadmium sulfide, Photoresist processing, Chemically amplified resists, Cadmium, Scattering, Backscatter, Lithography, Modulation

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Proceedings Article | 25 September 2010 Paper

Geometrically induced dose correction method for e-beam lithography applications

R. Galler, K.-H. Choi, M. Gutsch, C. Hohle, M. Krueger, L. E. Ramos, M. Suelzle, U. Weidenmueller

Proceedings Volume 7823, 78231E (2010) https://doi.org/10.1117/12.864263

KEYWORDS: Electron beam lithography, Line edge roughness, Cadmium sulfide, Scattering, Laser scattering, Convolution, Photoresist processing, Modulation, Chemically amplified resists, Electron beams

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Proceedings Article | 25 September 2010 Paper

Multi-shaped e-beam technology for mask writing

Juergen Gramss, Arnd Stoeckel, Ulf Weidenmueller, Hans-Joachim Doering, Martin Bloecker, Martin Sczyrba, Michael Finken, Timo Wandel, Detlef Melzer

Proceedings Volume 7823, 782309 (2010) https://doi.org/10.1117/12.865708

KEYWORDS: Photomasks, Vestigial sideband modulation, Beam shaping, Metals, Lithography, Electron beam lithography, Optical proximity correction, Source mask optimization, Computational lithography, Integrated optics

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Proceedings Article | 15 May 2010 Paper

Multi-shaped beam data preparation

U. Weidenmueller, H.-J. Doering, R. Jaritz, D. Melzer, A. Stoeckel

Proceedings Volume 7545, 754506 (2010) https://doi.org/10.1117/12.864245

KEYWORDS: Beam shaping, Photomasks, Single sideband modulation, Medium wave, Resolution enhancement technologies, Lithography, Electron beam lithography, Electron beams, Critical dimension metrology, Data processing

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Proceedings Article | 23 September 2009 Paper

Latest results and computing performance of the ePLACE data preparation tool

J. Gramss, R. Galler, V. Neick, A. Stoeckel, U. Weidenmueller, D. Melzer, M. Suelzle, J. Butschke, U. Baetz

Proceedings Volume 7488, 748827 (2009) https://doi.org/10.1117/12.835880

KEYWORDS: Photomasks, Beam shaping, Data conversion, Magnesium, Electron beam lithography, Data processing, Visualization, Standards development, Lithography, Computer architecture

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Proceedings Article | 27 May 2009 Paper

High resolution cell projection

U. Weidenmueller, P. Hahmann, M. Lemke, B. Schnabel, L. Pain, S. Manakli

Proceedings Volume 7470, 74700P (2009) https://doi.org/10.1117/12.835187

KEYWORDS: Vestigial sideband modulation, Electron beam direct write lithography, Electron beam lithography, Beam shaping, Scanning electron microscopy, Standards development, Lithography, Prototyping, Semiconducting wafers, Electron beams

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The ever more demanding requirements in the semiconductor manufacturing sector together with the increasing mask making costs and cycle times call for new lithographic solutions. Electron beam lithography has shown its superior performance and flexibility in advanced patterning applications. It enables already today process and technology developments ahead of the ITRS roadmap, which addresses currently the 32nm and 22nm node or even below. Thus electron beam direct write (EBDW) can avoid the high costs and delay times related to the advanced masks required for critical layers. On the other side EBDW faces the concerns regarding its throughput, which bases upon the inherited sequential exposure method. A solution to improve the throughput performance offers the implementation of the cell projection method as already materialized in the Vistec SB3055 tool. In addition to the variable shape beam technology, which can project regular structures (rectangles, slants and triangles) only, cell projection is able to image complex structures. Thus, structures that would have required a multiple of regular shots are now projected in one single shot. Thanks to this approach not only the shot count is noticeably reduced, but also the overall throughput is increased. First experimental and simulation results show an improvement of a factor of about 3X. Nevertheless, the final throughput gain strongly depends on the pattern and data structure itself. Combining high resolution variable shape beam technology with the cell projection feature allows advanced R&D and small volume and prototyping applications to be performed with one system. The Vistec SB3055 features the high resolution capability of variable shape beam lithography and incorporates the advantages of the cell projection technology. Owing to this new option we are able to improve the throughput for standard design features while maintaining the required high accuracy of our exposure system. Beside this, the combination of cell projection and standard shape beam technology still offers a high degree of flexibility as the key advantage of EBDW. On the Vistec SB3055 system we have performed different resolution tests serving as comparison between cell projection and standard shape beam. In this paper we will present the resolution capability obtained with cell projection on test structures as well as the general accuracy achieved for real patterns.

Proceedings Article | 2 May 2008 Paper

New alignment marks for improved measurement maturity

U. Weidenmueller, H. Alves, B. Schnabel, B. Icard, L. Pain, J.-C. Le Denmat, S. Manakli, J. Pradelles

Proceedings Volume 6792, 679211 (2008) https://doi.org/10.1117/12.798788

KEYWORDS: Optical alignment, Semiconducting wafers, Optical lithography, Electron beams, Electron beam direct write lithography, Lithography, Signal to noise ratio, Overlay metrology, Signal detection, Wafer testing

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Proceedings Article | 26 March 2008 Paper

E-beam direct write alignment strategies for the next generation node

H. Alves, P. Hahmann, K.-H. Kliem, U. Weidenmueller, S. Jahr, C. Frase, D. Gnieser, H. Bosse, R. Zimmermann, C. Arndt

Proceedings Volume 6921, 69210I (2008) https://doi.org/10.1117/12.771585

KEYWORDS: Optical alignment, Monte Carlo methods, Sensors, Silicon, Signal to noise ratio, Signal detection, Semiconducting wafers, Vestigial sideband modulation, Electron beam direct write lithography, Lithography

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Proceedings Article | 16 June 2003 Paper

Mix and match capability of e-beam direct-write for the 65-nm technology

Yves Laplanche, Murielle Charpin, Laurent Pain, J. Todeschini, Daniel Henry, Pierre-Olivier Sassoulas, S. Gough, Ulf Weidenmueller, Peter Hahmann

Proceedings Volume 5037, (2003) https://doi.org/10.1117/12.482342

KEYWORDS: Semiconducting wafers, Scanners, Optical alignment, Electron beam direct write lithography, Distortion, Overlay metrology, Electron beam lithography, Photomasks, Optical lithography, Error analysis

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