Partner: Helmut Schift

Paul Scherrer Institut (CH)

Recent publications
1.Jarząbek D.M., Siewert D., Fabianowski W., Schift H., Rymuza Z., Jung T., Influence of Alkali Ions on Tribological Properties of Silicon Surface, TRIBOLOGY LETTERS, ISSN: 1023-8883, DOI: 10.1007/s11249-015-0603-5, Vol.60, No.2, pp.1-8, 2015
Abstract:

Tribological properties of surfaces (friction, adhesion and wear) provide challenging limitations to the design of reliable machines on the micro- and nanometer scale as the surface to volume area increases and volume, mass and inertia of the mobile parts decrease. This study reports on the reduction in the friction force of silicon surfaces after the alkali metal ion exposure in the form of aqueous solutions. A scanning force microscope equipped with a liquid cell was used to investigate the friction force and the pull-off force of a flat silicon surface immersed in water and in different alkali metal chlorides solutions: LiCl, NaCl and CsCl. The concentration ranged from 0.1 up to 1000 µmol/l. The changes in the free surface energy of the initial surface and of the modified surfaces after drying were determined from contact angle measurements and from the acid–base adhesion theory. In both cases, in the liquid environment and after drying of the exposed silicon substrates in air, the friction force is reduced by approximately 50 %. Our results provide new, fundamental insight into the exchange of surface termination layers in particular for tribology. Also it is suggested to use the procedure as a low-cost alternative to improve the tribological properties of the silicon surface in particular in applications where lubricating fluids are not appropriate, e.g., in nanomachines and devices.

Keywords:

Silicon surface, Scanning force microscopy, Friction, Adhesion, Alkali metal chlorides

Affiliations:
Jarząbek D.M.-IPPT PAN
Siewert D.-Paul Scherrer Institut (CH)
Fabianowski W.-Paul Scherrer Institut (CH)
Schift H.-Paul Scherrer Institut (CH)
Rymuza Z.-other affiliation
Jung T.-Paul Scherrer Institut (CH)
2.Jarząbek D.M., Kaufmann A.N., Schift H., Rymuza Z., Jung T.A., Elastic modulus and fracture strength evaluation on the nanoscale by scanning force microscope experiments, NANOTECHNOLOGY, ISSN: 0957-4484, DOI: 10.1088/0957-4484/25/21/215701, Vol.25, pp.215701-1-9, 2014
Abstract:

This work first reviews the capability of scanning force microscopy (SFM) to perform experiments with forces in a wide range, from low non-contact forces to high contact forces which induce mechanical deformations in the substrate. In analogy to fracture strength evaluation, as established in materials science, SFM is used to exert forces on pillars with nanometer dimensions while the cantilever deformations are monitored quantitatively. Hence, it is possible to bend the pillars until the threshold for triggering fracture is reached, and to determine the mechanical properties at the different stages of this process. Using this novel approach, in combination with 'state of the art' nanofabrication to produce nanopillar arrays on silicon and silicon dioxide substrates, a number of experiments are performed. Furthermore, quantitative measurements of the fracture strength of Si and of the SiO2/Si interface and E-modulus are presented. To analyze the experimental data obtained in the different experimental procedures and modes, finite element method calculations were used. The methods introduced herein provide a versatile toolbox for addressing a wide range of scientific problems and for applications in materials science and technology.

Affiliations:
Jarząbek D.M.-IPPT PAN
Kaufmann A.N.-Paul Scherrer Institut (CH)
Schift H.-Paul Scherrer Institut (CH)
Rymuza Z.-other affiliation
Jung T.A.-Paul Scherrer Institut (CH)
3.Atasoy H., Vogler M., Haatainen T., Schleunitz A., Jarząbek D., Schift H., Reuther F., Gruetzner G., Rymuza Z., Novel thermoplastic polymers with improved release properties for thermal NIL, MICROELECTRONIC ENGINEERING, ISSN: 0167-9317, DOI: 10.1016/j.mee.2011.01.080, Vol.88, pp.1902-1905, 2011
Abstract:

In the nanoimprint lithography (NIL) process the mould release is a limiting step. Regardless of the carefully designed special properties a resist may have, it has to come over this challenging process step to be employed in a NIL process. Generally, the moulds are coated with anti-sticking layers. Here, an alternative solution is developed by modification of two well established NIL polymers through integration of fluorinated additives in their formulation. An effective additive concentration window was successfully defined, in which the substrate adhesion and imprint behaviour is not influenced. Defect-free patterning down to 30 nm is possible. A release force reduction of about 40% was observed with the modified polymer mr-I 7000R compared to the unmodified original

Keywords:

NIL polymers, Fluorinated additives, Release forces

Affiliations:
Atasoy H.-other affiliation
Vogler M.-other affiliation
Haatainen T.-other affiliation
Schleunitz A.-other affiliation
Jarząbek D.-other affiliation
Schift H.-Paul Scherrer Institut (CH)
Reuther F.-other affiliation
Gruetzner G.-other affiliation
Rymuza Z.-other affiliation