Publications de Wilfried Noell

Tolerancing the surface form of aspheric microlenses manufactured by wafer-level optics techniques

Wilfried Noell, Toralf Scharf, Jeremy Béguelin

Tolerancing is an important step toward the fabrication of high-quality and cost-effective lens surfaces. It is critical for wafer-level optics, when up to tens of thousands microlenses are fabricated in parallel and whose surfaces cannot be formed individ ...

OPTICAL SOC AMER2020

Optical characterization of high numerical aperture microlenses for quality assessment and fabrication process optimization

Wilfried Noell, Toralf Scharf, Jeremy Béguelin

Accurate characterization of high numerical aperture aspheric microlenses currently is a nonstandard procedure that remains an open challenge. Here, we present and discuss a characterization method based on interferometric and point spread function measure ...

OPTICAL SOC AMER2020

Correction of spherical surface measurements by confocal microscopy

Wilfried Noell, Toralf Scharf, Jeremy Béguelin

Refractive microlenses are nowadays widely used in optical systems. Characterizing their surface is essential to ensure their quality and to optimize their fabrication process. This is realized by optical surface profilers thanks to their vertical resoluti ...

2020

Specification of aspherical surfaces used as refractive elements in micro-optical systems

Wilfried Noell, Toralf Scharf, Jeremy Béguelin

The optical performance of refractive plano-convex microlenses is mainly related to the quality of their (a)spherical surface. An efficient tolerancing of this surface is a key step towards the manufacturing of high quality microlenses. However, we demonst ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Leveraging wafer-level manufacturing process limitations to increase large scale fused silica microlens array uniformity

Wilfried Noell, Toralf Scharf, Jeremy Béguelin, Raoul Kirner

The wafer-level production of Fused Silica microlens arrays is limited by systematic process non-uniformities. The common molten resist-reflow process with subsequent dry-etching allows for manufacturing of microlens arrays on 200 mm wafers. A thorough pro ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Correction of surface error occurring in microlenses characterization performed by optical profilers

Wilfried Noell, Toralf Scharf, Jeremy Béguelin

Characterizing the surface of microlenses by optical profilers has the important advantages of measurement speed, flexibility and automation. Nevertheless, the accuracy of such characterization is limited by error occurring in non-flat measurements. Here, ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Spatial coherence properties of an LED-based illumination system for mask-aligner lithography

Hans Peter Herzig, Wilfried Noell, Toralf Scharf, Johana Bernasconi, Raoul Kirner

A high-power LED-based illumination system has been developed as a replacement for the mercury arc lamps used in mask-aligner lithography. LEDs are arranged in a grid array and placed in the entrance aperture of individual reflectors. Those reflectors decr ...

SPIE2019

Computational rule-based approach for corner correction of non-Manhattan geometries in mask aligner photolithography

Wilfried Noell, Toralf Scharf, Chen Yan, Raoul Kirner, Andreas Vetter

In proximity mask aligner photolithography, diffraction of light at the mask pattern is the predominant source for image shape distortions such as line end shortening and corner rounding. One established method to mitigate the impact of diffraction is opti ...

2019

Improvements on the uniformity of large-area microlens arrays in Fused Silica

Wilfried Noell, Toralf Scharf, Jeremy Béguelin, Raoul Kirner

The uniformity of large microlens arrays in Fused Silica is governed by the production process. It comprises photolithographic patterning of a spin-coated layer of photoresist on a 200mm wafer with a molten resist reflow process and subsequent dry etching. ...

OPTICAL SOC AMER2019

Printing sub-micron structures using Talbot mask-aligner lithography with a 193 nm CW laser light source

Wilfried Noell, Toralf Scharf, Raoul Kirner, Andreas Vetter

A continuous improvement of resolution in mask-aligner lithography is sought after to meet the requirements of an ever decreasing minimum feature size in back-end processes. For periodic structures, utilizing the Talbot effect for lithography has emerged a ...

2018

High power modular LED-based illumination system for lithography applications

Hans Peter Herzig, Wilfried Noell, Marcel Groccia, Toralf Scharf, Johana Bernasconi, Raoul Kirner

Mask-aligner lithography is a technology used to transfer patterns with critical dimensions in the micrometer range from below 1 micron for contact printing to a dozen of microns in proximity printing. This technology is widely used in the fabrication of M ...

2018

Mask-aligner Talbot lithography using a 193 nm CW light source

Wilfried Noell, Toralf Scharf, Raoul Kirner, Andreas Vetter

We present and discuss Talbot mask-aligner lithography, relying on a continuous wave laser emitting at 193nm for the illumination. In this source, a diode laser at 772nm is amplified by a tapered amplifier in master-oscillator power-amplifier configuration ...

2018

Semiconductor-based narrow-line and high-brilliance 193-nm laser system for industrial applications

Wilfried Noell, Toralf Scharf, Xiaolong Wang, Raoul Kirner, Andreas Vetter

We present a novel industrial-grade prototype version of a continuous-wave 193 nm laser system entirely based on solid state pump laser technology. Deep-ultraviolet emission is realized by frequency-quadrupling an amplified diode laser and up to 20 mW of o ...

2018

Assessing microlens quality based on 3D irradiance measurement at the focal spot area

Wilfried Noell, Toralf Scharf, Jeremy Béguelin, Michail Symeonidis

During the fabrication process of microlenses, characterization is essential for two purposes: evaluate the optical quality of the element and provide surface information feedback for process optimization. However, no technique can fulfill these two object ...

2018

Improved calibration of vertical scanning optical profilometers for spherical profiles measurements

Wilfried Noell, Toralf Scharf, Jeremy Béguelin

A new method for calibrating optical scanning profilometers is presented. Especially adapted to spherical and aspherical profile measurements, it shows an increase of accuracy bigger than one order of magnitude for radius of curvature measurements. Calibra ...

2018

Enabling proximity mask-aligner lithography with a 193nm CW light source

Wilfried Noell, Toralf Scharf, Raoul Kirner, Andreas Vetter

We introduce a novel industrial grade 193nm continuous-wave laser light source for proximity mask-aligner lithography. A diode seed laser in master-oscillator power-ampliﬁcation conﬁguraton is frequency-quadrupled using lithiumtriborate and potassium-ﬂuoro ...

2018

Improving the resolution in mask-aligner lithography

Wilfried Noell, Toralf Scharf, Raoul Kirner, Andreas Vetter

For the back-end microfabrication in integrated circuits and for the manufacturing of light emitting diodes, proximity mask-aligner lithography is still the tool of choice, due to its simplicity and low costs. However, the downscaling of functional element ...

IEEE2018

Refraction limit of miniaturized optical systems: a ball-lens example

Hans Peter Herzig, Wilfried Noell, Roland Andreas Bitterli, Myun Sik Kim, Toralf Scharf

We study experimentally and theoretically the electromagnetic field in amplitude and phase behind ball-lenses across a wide range of diameters, ranging from a millimeter scale down to a micrometer. Based on the observation, we study the transition between ...

Optical Society of America2016

Array imaging system for lithography

Wilfried Noell, Toralf Scharf, Raoul Kirner

We present an integrated array imaging system based on a stack of microlens arrays. The microlens arrays are manufactured by melting resist and reactive ion etching (RIE) technology on 8'' wafers (fused silica) and mounted by wafer-level packaging (WLP)(1) ...

Spie-Int Soc Optical Engineering2016

Lightfields behind amplitude masks: Creating phase discontinuities

Hans Peter Herzig, Wilfried Noell, Myun Sik Kim, Toralf Scharf, Krishnaparvathy Puthankovilakam

Shaping of light fields behind amplitude and phase masks the basis the lithographic structure reproduction. The aerial image or better the intensity distribution defines the resolution of the structure to be printed. Contrast is the main parameter and to a ...

Ieee2016