Work Activities
In semiconductor device manufacturing, metrology tools are required for wafer alignment, overlay and device inspection. As devices become more complicated and as stronger light sources are being used to get sufficient signal from samples covered with optically opaque layers, optical damage can occur. Catastrophic damage is easily detected. However, there are forms of non-catastrophic optical damage (or more generally, subtle material modifications) that are difficult to observe.

Recently, we have shown that subtle structural changes in a material can lead to subtle changes in the optical response of the material in visible/near-infrared part of the optical spectrum and that light emission at terahertz (THz) frequencies can yield equally relevant, complementary information. THz radiation in particular has been shown to be sensitive to nanoscale electrical conductivity.

Project goal
In this project you will use THz, near-infrared, and visible light to measure subtle changes in structure and conductivity induced by exposure to light (pulses). You will focus on materials currently relevant for the semiconductor industry, and on those relevant for future applications. The spatial scales at which these subtle light-induced changes occur is determined by the pump laser exposure area and can be in the sub-micrometer to tens of micrometer range. This is below the diffraction limit of THz light which has wavelengths in the several tens to hundreds of micrometer range. For this reason, you will explore near-field techniques when using THz light to measure conductivity. Higher (~ a few microns) resolution imaging will be used for visible/near-IR probing to measure small reflection changes induced by subtle morphological/conductivity changes induced by ultrashort laser pulses.

After you join our group, your goal is to design and execute optical and THz experiments to measure and understand the nature of the subtle material changes created by exposure to laser pulses. You will learn to work with high-power femtosecond lasers, with detectors and diagnostic tools like SEM, AFM and others, and learn how to analyze your data.

Qualifications
You have (or soon will have) a MSc degree in physics, chemistry, or materials science or equivalent, to satisfy the Dutch university requirement to enter a PhD program. Previous experience with lasers is not required but it would be a plus. An interest in non-linear optics, materials science and chemistry is needed, as are critical thinking, and creative problem-solving skills. Good verbal and written communication skills in English are required.

Work environment
The Advanced Research Center for Nanolithography (ARCNL) focuses on the fundamental physics and chemistry involved in current and future key technologies in nanolithography, primarily for the semiconductor industry. ARCNL is a public-private partnership between the Dutch Research Council (NWO), the University of Amsterdam (UvA), the VU University Amsterdam (VU), associate partner the University of Groningen (RuG), and the semiconductor equipment manufacturer ASML.

ARCNL is located at the Amsterdam Science Park, The Netherlands, and has a size of approximately 100 scientists and support staff. See also www.arcnl.nl.

About the Light/Matter Interaction group
The research activities of the Light/Matter Interaction group focus on the optical and terahertz response of materials within the context of photo-acoustics and light-induced damage. Ultrashort THz pulses play an increasingly larger role in discovering the response of materials to intense light, both by measuring the emission of THz light by materials after exposure to intense laser pulses, and by using THz light as a probe to measure light-induced material changes.

Working conditions
The position is intended as full-time (40 hours / week, 12 months / year) appointment in the service of the Netherlands Foundation of Scientific Research Institutes (NWO-I) for the duration of four years, with a starting salary of gross € 2,781 per month and a range of employment benefits. After successful completion of the PhD research a PhD degree will be granted at a Dutch University. Several courses are offered, specially developed for PhD-students. ARCNL assists any new foreign PhD-student with housing and visa applications and compensates their transport costs and furnishing expenses.

More information?
For further information about the position, please contact Paul Planken: p.planken@arcnl.nl.

Application
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Diversity code
ARCNL is highly committed to an inclusive and diverse work environment: we want to develop talent and creativity by bringing together people from different backgrounds and cultures. We recruit and select on the basis of competencies and talents. We strongly encourage anyone with the right qualifications to apply for the vacancy, regardless of age, gender, origin, sexual orientation or physical ability.

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