Tommi SUNI, Dr.

 Tommi_SUNI.jpg Host Laboratory FUJITA LAB.
Position in LIMMS EUJO-LIMMS Researcher (VTT)
Main Research Topic in LIMMS

Advanced-MEMS - TEM analysis on AlN thin films


TEM, FIB, AlN, Piezo-electric thin films, Piezo-MEMS 


Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
Phone:+81 (0)3 5452 6036 / Fax:+81 (0)3 5452 6088


VTT Technical Research Centre of Finland 
Tietotie 3, P.O. Box 1000, FI-02044 VTT, Espoo, Finland 
Tel. +358 40 8251703  /  Fax +358 20 722 7012

E-mail suni at
Download icon_pdf.gifAbstract2015_TSuni.pdf


Short resume :
2012-now Actual position
2008-2012 Here
2004-2008 Here
2001-2003 Here

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Research Projects in Limms

1- TEM analysis on AlN thin films
Context :
VTT is very active in developing piezo-electric thin films for advanced piezo-MEMS devices. It has been observed that the performance of such films is also highly dependent on the seed layer used and can vary a lot even within the wafer. The reason for this is unclear. Fujita lab has large number of sophisticated characterization tools suitable for evaluation of the crystallography of the films. The topic was found suitable for EUJO-LIMMS project and Tommi Suni from VTT carried out the work in IIS during 2.5 month visit in spring 2014. 
Objectives & Methods :
The objective is to get better understanding on the growth of the AlN layers. Main area of the interest is near the interface between seed layer and the AlN film. VTT prepared 5 sample wafers having AlN on Si, on high resistivity Si, on two types of Molybdenum layers and on another AlN layer. The wafers were diced to 1 cm x 1 cm chips and focused ion beam (FIB) was used for TEM sample preparation. The TEM sample observation was done using first scanning TEM and then high resolution TEM. 
Results :
Total 40 TEM samples were prepared using FIB. From these 20 were characterized using STEM and/or HR-TEM (Figure 1) and total over 500 TEM images were taken. With HR-TEM crystallographic planes on AlN were nicely observed on high magnification images (Figure 2). However, it was impossible to see the interface between the seed layer and the AlN film in high magnification images and therefore crystallographic analysis on the most important region was challenging. 


Fig. 1 10k magnification TEM image of AlN film on Molybdenum


Fig. 2 1200k  magnification TEM image of AlN film on Molybdenum

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Main publication List (papers, conferences and patent)








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