Novel EUV lithography path using surface functionalization and low energy electron induced chemistry

Leuven - PhD
More than two weeks ago

You will work together with a team of deposition and lithography specialists within an international environment in a modern 300 mm semiconductor cleanroom using advanced tools at the leading-edge technology. You will be trained in entrepreneurial skills necessary to bring such research from the laboratory to development phase.


Topic description: This PhD project aims to develop novel processes for selective area deposition (ASD) through research novel patterning schemes and to consolidate their applications in the semiconductor manufacturing industry.


The extreme ultra-violet (EUV) lithography, at a wavelength of 13.5 nm is the leading-edge technology to pattern small features and recently it has been introduced for high-volume manufacturing (HVM) in the semiconductor industry for the 7 nm technology node (N7). However, to enable the future technology nodes (N5, N3 and beyond) further efforts are needed to extend EUVL usage for sub-10nm features. As the wavelength of light decreases in photolithography its depth of focus also reduces, thus ultrathin photoresists (PR) are required.

Structured thin organic films, such as self-assembled monolayers (SAMs) bearing photosensitive groups or acting as a seeding layer for further molecular grafting, can be innovative and effective candidates for the resist layer for PL using shorter wavelength lights. The advantage is that they are more chemically stable than typical metal-oxide cluster based or chemically amplified resists and have a more well-organized structure than random polymers. If their end groups are prepatterned with light, one can make functional nanopatterns by attaching molecules with specific functional groups on the surface.

Area-selective deposition (ASD) by atomic layer deposition (ALD) of typical hard mask materials (HM) such as TiN or TiO2, can be promoted only in the irradiated or not-irradiated areas of the film, depending on interaction with ALD precursors and co-reactants in the specific ALD conditions (see Figure 1).


ALD TiOx deposition

 Figure 1: 200 nm lines/squares after ALD TiOx deposition. Lines grow in the activated surface electron-induced


Just as an example, photo responsive surface chemistry can be achieved by exploiting furoxan functionalities anchored to the surface via amino-terminated ordered SAMs. By exposing different structures containing rings and furoxans to EUV light, triple bonds terminations can be generated with a substantial local selective modification of the surface energy and reactivity towards ALD. In addition, alkyne moieties can be used for anchoring other molecules via Huisgen [2+] cycloaddition with azides (click chemistry) making them a powerful method for surface engineering.

Critical for success is the development of an understanding of the surface/interface chemistries/reactions induced by chemical grafting as this provides the platform for the remainder of the research program.

The development of suitable metrology and characterization techniques and the fundamental understanding and modification of existing models will be a substantial part of the post-doc program. Various tools have been used to characterize organic surfaces with varying degrees of success and detail. The most popular has been X-ray photoelectron spectroscopy which can monitor the density of the grafted functional groups. XPS is also useful for the measurement of the thickness of thin coatings, via overlayer equations. Total x-ray fluorescence can be used to estimate the functional groups density assumed the labeling atom can be detected by such a technique (i.e. Br, etc...). Other techniques such as ellipsometry and atomic force microscopies (AFM) can be used to measure the thickness but require the development of suitable models. Attenuated total reflectance FT-IR spectroscopy can be used to identify the chemical groups together with their derivatization or extraction.  Characterization of structures with dimensions approaching those of atoms is required. Several advanced techniques for the characterization of nano-structures have recently been developed: various kinds of microscopy, gas-adsorption porosimeter, ellipsometry, transmission neutron and x-ray scattering with specular x-ray reflectivity, and grazing incidence scattering. However, no all-encompassing technique is currently available. Thus, a synergistic approach, i.e. the application in combination of various analytical techniques to obtain results superior to those obtained with each individual technique, is necessary and will be explored in this work.


Principle Duties and Responsibilities

The PhD candidate will · Acquire a wide knowledge of surface engineering by grafting or organic films  relevant to the work program outlined above · Be able to identify key problems, generate novel solutions and reduce them to practice · Acquire a wide knowledge on Extreme Ultraviolet lithography, EUV resists and their characterization/integration relevant to the work program outlined above  · Disseminate the results of such activities to internal colleagues/partners and capture relevant intellectual property via patent applications and/or publish results in high impact journals and conferences · Bring an energetic and enterprising approach to the execution of the research program · Potentiate inter-personal skills suitable for playing a role at the center of a complex multidisciplinary teams · Be alert to unexpected opportunities arising during the research · Assist with the training of graduated or undergraduate students working in the area of the project · Develop written and oral communication skills.

Required background: chemistry, chemical engineering, physics, material science. Knowledge of X-ray / soft-X ray spectroscopy and electron/light-matter interaction are an advantage.

Type of work: The main aspects of the described work are: technology study combined with fundamental understanding of surface reactions, light(EUV)-matter interaction, interface structure and nanoscale material engineering and it is mainly experimental. Nevertheless, modeling opportunities via collaborations might also be part of the PhD work.

Promotor: Stefan De Gendt

Daily advisors: Danilo De Simone/Silvia Armini


Required background: chemistry, chemical engineering, physics, material science. Knowledge of X-ray / soft-X ray spectroscopy and electron/light-matter interaction are an advantage.


Type of work: 60% experimental, 35% data analysis and reporting, 5% literature

Supervisor: Stefan De Gendt

Daily advisor: Danilo De Simone, Silvia Armini

The reference code for this position is 2020-040. Mention this reference code on your application form.


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