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Surface Physics for Advanced Manufacturing

Final Report Summary - SPAM (Surface Physics for Advanced Manufacturing)

Today, markets demand smaller, cheaper, energy friendly and more different consumer products. Micro technology has opened possibilities for mobile communication, safety and health science products. To meet these demands, the industry encounters technological barriers that prevent from evolving from the micro to a nano-technology era. To resolve these barriers, the industry and research institutes need to structure, initiate and integrate research programs and to transfer the knowledge that has been acquired in these programs. New researchers have to be trained with excellent research skills and knowledge on the specific technology. For this purpose 4 industrial, 5 academic and 3 research institutes have defined the 4 year S.P.A.M. research and training program; a Supra-disciplinary approach to research and training in surface Physics for Advanced Manufacturing.
The research objectives are: to identify and develop crucial knowledge in the field of surface physics required for optical lithography technology which will enable the manufacturing of smaller semi-conductors by printing features under 32 nm with extreme positional accuracy (< 4 nm).
The research methodology in the project is built on the interaction of four research teams, viz. contact line (in)stability, surface cleanliness, controlled surface roughness and structured surface metrology.

In the research on contact line (in)stability experimental methods as well as analytical and numerical models are developed for this fundamental multi-scale physics problem. First results have been obtained on plasma nanotextured superhydrophobic surfaces to improve the stability of the receding liquid meniscus and investigations of hydrophilic and hydrophobic micro channels and corrections of particle image velocimetry were performed.
Experiments for water stability of plasma deposited CF coatings have shown that such coatings can withstand immersion for almost one month without significant contact angle degradation.
A method was derived to for non-contact optical measurement of small temperature differences in a liquid using a particle image velocimetry (PIV) set up. Also the microscopic fluid flow inside small droplets that dry by evaporation has been measured as well as the relation to the formation of drying marks was explained.
In another study the impact of a focused N2-knife flow on the drying part of a contact line was studied experimentally. Furthermore, the impact of such a gas flow on droplet movement was studied experimentally and by computation fluid dynamics simulation.

A fast detection method for surface contamination based on ellipsometry was developed in the research on surface cleanliness. It allows for distinguishing between different types of contamination on EUV multilayer mirrors. Detailed experimental investigations of adsorption and desorption processes and kinetics of different contaminants on single crystalline surfaces as model systems for EUV multilayer mirror optics have been performed. This knowledge was transferred to real EUV multilayer mirrors and resulted in a new surface analysis technique for studying surface contaminations based of so-called factor analysis and inelastic background analysis. Deep insights of reduction and oxidation processes on single crystal material were generated. Based on this experience an atomic hydrogen sensor and a setup for studying the hydride generation and decomposition process was developed. Detailed studies on contamination issues and their analysis in FOUPs and vacuum pumps were performed. In addition a very detailed research program on hydrogen based plasmas and their diagnostic happened.

Careful control of surface roughness and surface energy is required to avoid Van der Waals and capillary adhesion. Experimental research is done on the modification of surfaces whereby ion beam patterning is used to create shallow nano- patterns that are characterized by both roughness as well as spatial periodicity. Also, surface modification is used to create a monolayer of fluorinated polymer to decrease the surface energy. Both techniques, ion beam patterning and chemical surface modification, are tested for wear-resistance.

For line-edge-roughness (LER) metrology with angular resolved scatterometry, the new method developed in the first reporting period of the project has been consolidated, and has been successfully tested on experimental data as obtained with the YieldStar tool (recorded at ASML).
Phase-retrieval with coherent detection has been enabled via a new hardware concept that is based on sequential acquisition of diffraction patterns for different positions of a focused laser beam along the unit cell of the diffraction grating. The method was evaluated via a breadboard set-up. A substantial improvement (a factor 3 to 5) in precision for profile reconstruction of diffraction gratings could be achieved in this way.
With the improved methodology developed for contact edge roughness (CER) measurement and characterization, the effects of exposure dose, PAG sensitizer and quencher concentrations on CER and critical dimension uniformity (CDU) for two EUV resists were investigated. An abstractive model for the formation of CER during the lithographic process has also been developed.

Timely availability of researchers and results supporting the technology for lithography and metrology are a prerequisite for realization of the leading International Technology Roadmap for Semiconductors that ensures advancements in performance of IC’s and supports the continuation of Moore’s law (describing that the number of transistors that can be placed inexpensively on an integrated circuit doubles approximately every two years). The progress in performance of products based on these advanced IC’s supports the economical growth in many areas such as health care, mobile devices, high speed communication.

Contact details:
Dr. Gerold E. Alberga
S.P.A.M. network coordinator
ASML Netherlands B.V.
e-mail: gerold.alberga@asml.com