Electronics offer innovative ways to communication, work and live and integrated circuits (ICs) appear in various applications in our daily lives. Over the past five decades, the ICs have seen a continuous increase of computing power while at the same time increasing performance. To achieve this, the number of transistors on the ICs must increase per unit area. This trend, known as Moore's law, predicts that the number of transistors on an IC doubles every two years. In lithography, the smallest feature size, or critical dimension (CD), possible depends on the wavelength 𝜆 of the source, the numerical aperture (NA) of the optical system and a correction factor 𝑘1 that accounts for non-ideal behavior. The miniaturization of feature sizes has been achieved mainly by shortening the wavelength of exposure tools. Currently, extreme ultraviolet light (EUV), with a wavelength of 13.5 nm, is a route to become the source of the next generation lithography that enables more powerful chips. The further development of EUV lithography (EUVL) is heavily based on implementing the so-called high-NA EUVL, in which the current NA-value of 0.33 is increased to 0.55 to get even better resolution. In anticipation of the high-NA technology, the focus is now shifted towards resist development.
The resist has an important part to play in every lithography process by transferring the information present on the mask (e.g. all the patterns) to the substrate when irradiated with light. Throughout the optimization of lithographic technologies, a first challenge is the continuous downscaling of the film thickness of the lithography materials (resist and underlayers). The reason for this is twofold in that going to smaller wavelengths (i.e. higher energy electrons) means that the absorption of the radiation can only be kept homogeneous by reducing the film thickness. Therefore, because of the continuous downscaling envisioned for high-NA technology, both photoresist film thicknesses (10 – 35 nm) and underlying film thicknesses (3 – 20 nm) are approaching the ultra-thin film regime, at and beyond the physical limits of bulk-phase behavior. Because of this, the interface interactions between the different layers (e.g. resist and underlayer) become increasingly dominant in ultra-thin films. Therefore, a second challenge appears to be related to the inherent material characteristics that change in function of the film thickness.
This project will explore the limitations of resists with respect to film thickness and focus on the characterization of changes that happen with going to the ultra-thin film regime necessary for high-NA. This work will significantly contribute to the understanding of resist interaction and changes with respect to film thickness and will lead to help the design of new photoresists for EUV lithography. The student will work in the international research facility of imec interacting with multiple equipment and material partners. To accomplish this task, the student must have a chemistry, nano-technology or materials science background, basic knowledge on statistics and a liking for the design of experiments, their execution and data analysis.
Type of project: Internship, Thesis, Combination of internship and thesis
Duration: 9 months
Required degree: Master of Engineering Technology, Master of Science, Master of Engineering Science
Required background: Chemistry/Chemical Engineering, Materials Engineering, Nanoscience & Nanotechnology, Physics
Supervising scientist(s): For further information or for application, please contact: Danilo De Simone (Danilo.DeSimone@imec.be)
Imec allowance will be provided