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Dive into the research topics where Lauri Kilpi is active.

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Featured researches published by Lauri Kilpi.


Journal of Vacuum Science and Technology | 2016

Microscratch testing method for systematic evaluation of the adhesion of atomic layer deposited thin films on silicon

Lauri Kilpi; Oili M. E. Ylivaara; Antti Vaajoki; Jari Malm; Sakari Sintonen; Marko Tuominen; Riikka L. Puurunen; Helena Ronkainen

The scratch test method is widely used for adhesion evaluation of thin films and coatings. Usual critical load criteria designed for scratch testing of coatings were not applicable to thin atomic layer deposition (ALD) films on silicon wafers. Thus, the bases for critical load evaluation were established and the critical loads suitable for ALD coating adhesion evaluation on silicon wafers were determined in this paper as LCSi1, LCSi2, LCALD1, and LCALD2, representing the failure points of the silicon substrate and the coating delamination points of the ALD coating. The adhesion performance of the ALD Al2O3, TiO2, TiN, and TaCN+Ru coatings with a thickness range between 20 and 600 nm and deposition temperature between 30 and 410 °C on silicon wafers was investigated. In addition, the impact of the annealing process after deposition on adhesion was evaluated for selected cases. The tests carried out using scratch and Scotch tape test showed that the coating deposition and annealing temperature, thickness of...


Journal of Vacuum Science and Technology | 2013

Characterization of thin film adhesion by MEMS shaft-loading blister testing

Maria Berdova; Kestutis Grigoras; Anu Baby; Lauri Kilpi; Helena Ronkainen; Sami Franssila; Jari Koskinen

A new microelectromechanical system shaft-loaded blister test was developed and demonstrated to provide stability, repeatability, and simultaneous quantitative measurements of adhesion between thin films deposited on a silicon substrate. The authors assessed adhesion of sputtered platinum, copper, and chromium/copper (300 nm) to underlaying atomic layer deposited (ALD) aluminum oxide. The average adhesion energies for thin films on ALD aluminum oxide were found to be 1.15 ± 0.1 J/m2 for platinum thin films, 1.4 J/m2 for copper thin films, and 1.75 J/m2 for chromium/copper.


Journal of Vacuum Science and Technology | 2017

Aluminum oxide/titanium dioxide nanolaminates grown by atomic layer deposition: Growth and mechanical properties

Oili M. E. Ylivaara; Lauri Kilpi; Xuwen Liu; Sakari Sintonen; Saima Ali; Mikko Laitinen; Jaakko Julin; Eero Haimi; Timo Sajavaara; Harri Lipsanen; Simo-Pekka Hannula; Helena Ronkainen; Riikka L. Puurunen

Atomic layer deposition (ALD) is based on self-limiting surface reactions. This and cyclic process enable the growth of conformal thin films with precise thickness control and sharp interfaces. A multilayered thin film, which is nanolaminate, can be grown using ALD with tuneable electrical and optical properties to be exploited, for example, in the microelectromechanical systems. In this work, the tunability of the residual stress, adhesion, and mechanical properties of the ALD nanolaminates composed of aluminum oxide (Al 2O3) and titanium dioxide (TiO2) films on silicon were explored as a function of growth temperature (110–300 °C), film thickness (20–300 nm), bilayer thickness (0.1–100 nm), and TiO2 content (0%–100%). Al 2O3 was grown from Me3 Al and H2O, and TiO2 from TiCl4 and H2O. According to wafer curvature measurements, Al 2O3/TiO2 nanolaminates were under tensile stress; bilayer thickness and growth temperature were the major parameters affecting the stress; the residual stress decreased with increasing bilayer thickness and ALD temperature. Hardness increased with increasing ALD temperature and decreased with increasing TiO2 fraction. Contact modulus remained approximately stable. The adhesion of the nanolaminate film was good on silicon.


Journal of Vacuum Science and Technology | 2018

Tribological properties of thin films made by atomic layer deposition sliding against silicon

Lauri Kilpi; Oili M. E. Ylivaara; Antti Vaajoki; Xuwen Liu; Ville Rontu; Sakari Sintonen; Eero Haimi; Jari Malm; Markus Bosund; Marko Tuominen; Timo Sajavaara; Harri Lipsanen; Simo-Pekka Hannula; Riikka L. Puurunen; Helena Ronkainen

Interfacial phenomena, such as adhesion, friction, and wear, can dominate the performance and reliability of microelectromechanical (MEMS) devices. Here, thin films made by atomic layer deposition (ALD) were tested for their tribological properties. Tribological tests were carried out with silicon counterpart sliding against ALD thin films in order to simulate the contacts occurring in the MEMS devices. The counterpart was sliding in a linear reciprocating motion against the ALD films with the total sliding distances of 5 and 20 m. Al2O3 and TiO2 coatings with different deposition temperatures were investigated in addition to Al2O3-TiO2-nanolaminate, TiN, NbN, TiAlCN, a-C:H [diamondlike carbon (DLC)] coatings, and uncoated Si. The formation of the tribolayer in the contact area was the dominating phenomenon for friction and wear performance. Hardness, elastic modulus, and crystallinity of the materials were also investigated. The nitride coatings had the most favorable friction and wear performance of the...


Thin Solid Films | 2014

Aluminum oxide from trimethylaluminum and water by atomic layer deposition: The temperature dependence of residual stress, elastic modulus, hardness and adhesion

Oili M. E. Ylivaara; Xuwen Liu; Lauri Kilpi; Dieter Schneider; Mikko Laitinen; Jaakko Julin; Saima Ali; Sakari Sintonen; Maria Berdova; Eero Haimi; Timo Sajavaara; Helena Ronkainen; Harri Lipsanen; Jari Koskinen; Simo-Pekka Hannula; Riikka L. Puurunen


Tribology International | 2014

Tribological properties of laser-textured and ta-C coated surfaces with burnished WS2 at elevated temperatures

Jussi Oksanen; Timo J. Hakala; Sanna Tervakangas; Petri Laakso; Lauri Kilpi; Helena Ronkainen; Jari Koskinen


Acta Materialia | 2014

Mechanical assessment of suspended ALD thin films by bulge and shaft-loading techniques

Maria Berdova; Tuomo Ylitalo; Ivan Kassamakov; J. Heino; Pekka Törmä; Lauri Kilpi; Helena Ronkainen; Jari Koskinen; Edward Hæggström; Sami Franssila


Thin Solid Films | 2014

Thermal and plasma enhanced atomic layer deposition of SiO2 using commercial silicon precursors

Matti Putkonen; Markus Bosund; Oili M. E. Ylivaara; Riikka L. Puurunen; Lauri Kilpi; Helena Ronkainen; Sakari Sintonen; Saima Ali; Harri Lipsanen; Xuwen Liu; Eero Haimi; Simo-Pekka Hannula; Timo Sajavaara; Iain Buchanan; Eugene Joseph Karwacki; Mika Vähä-Nissi


Tribology International | 2016

Tribocorrosion study of martensitic and austenitic stainless steels in 0.01 M NaCl solution

Elina Huttunen-Saarivirta; Lauri Kilpi; Timo J. Hakala; L. Carpén; Helena Ronkainen


Tribology International | 2016

The influence of carbon based coatings and surface finish on the tribological performance in high-load contacts

Helena Ronkainen; Oskari Elomaa; Simo Varjus; Lauri Kilpi; T. Jaatinen; Jari Koskinen

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Helena Ronkainen

VTT Technical Research Centre of Finland

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Jari Koskinen

VTT Technical Research Centre of Finland

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Oili M. E. Ylivaara

VTT Technical Research Centre of Finland

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Riikka L. Puurunen

VTT Technical Research Centre of Finland

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Timo Sajavaara

University of Jyväskylä

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