Papers

ICMCTF2010 Session B1-3: Sputtering Coatings and Technologies

Tuesday, April 27, 2010 8:00 AM in Room Pacific Salon 3

Tuesday Morning

Start	Invited?	Item
8:00 AM		B1-3-1 Sputter-Deposited Thin-Film AlN-Based Electro-Acoustic Devices for Biosensor Applications Gunilla Wingqvist (Linköping University, Sweden) Biosensors, using biological recognition elements for specific detection on a molecular level, are today important devices for applications ranging from medical, environmental to safety areas. A new type of label-free biosensor device has been developed and studied, which is fabricated using the same processes used for the fabrication of integrated circuits. This enables tighter integration and further sensor/biosensor miniaturization. The device is a so-called Thin Film Bulk Acoustic Resonator (FBAR). Developments are here reported of a low temperature reactive sputtering process for growing wurtzite-AlN thin films with a c-axis inclination of 20-30 degrees. This process enabled shear mode FBAR fabrication suitable for in-liquid operation, essential for biosensor applications. Shear mode FBARs were fabricated, operating at frequencies above 1GHz, exhibiting Q values of 100-200 in contact with water and electromechanical coupling factors k_t² of about 1.8%. This made it possible to move the thickness excited shear mode sensing of biological layers into a new sensing regime using substantially higher operation frequencies than the conventionally used quartz crystal microbalance (QCM) operating at 5-20 MHz. Measured noise levels of shear mode FBARs in contact with water showed the resolution to be in the range 0.3ng/cm² to 7.5ng/cm². This demonstrated the FBAR resolution without any averaging or additional stabilization measures already to be in the same range as the conventional QCM (5ng/cm²), suggesting that FBARs may be a competitive and low cost alternative to QCM. The linear thickness limit for sensing of biomolecular layers was concluded to be larger than the thickness of the majority of the molecular systems envisaged for FBAR biosensor applications. A temperature compensated shear mode FBAR composite structure was demonstrated with retained coupling factor and Qvalue by utilizing the second harmonic mode of operation. Understanding has been gained on the sensor operation as well as on how the design parameters influence its performance. Specifically, sensitivity amplification utilizing low acoustic impedance layers in the FBAR structure has been demonstrated and explained.
8:40 AM		B1-3-3 Enhancement of Bottom Electrode on Ferroelectric Properties and Fatigue Properties of BFO/STO Symmetrical Structure Shang-Jui Chiu (National Tsing Hua University, Taiwan); Hsin-Yi Lee (National Synchrotron Radiation Research Center, Taiwan); Ge-Ping Yu, Jia-Hong Huang (National Tsing Hua University, Taiwan) Superlattice structures consisting of symmetric multiferroic BiFeO₃ (BFO) and paraelectric SrTiO₃(STO) sublayers were successfully deposited with a RF magnetron sputtering system. Two popular electrode materials, (001) Nb-doped STO electrode and LaNiO₃ (LNO) electrode, were chosen to investigate the effect of bottom electrode on BFO/STO superlattice structure. J-V characteristics of BFO/STO superlattice films would be measured. Synchrotron X-ray study including azimuthal scan and Crystal truncation-rod (CTR) spectra confirmed the epitaxial growth of the superlattice films. CTR spectra along [2 0 0] direction also showed well strained effect of Nb-doped STO electrode and LNO electrode on BFO/STO superlattice films. BFO/STO superlattice films showed saturated P-E hysteresis loop, and the LNO bottom electrode which deposited on the single crystal STO (002) substrate showed better enhancement of ferroelectric properties and fatigue properties on BFO/STO superlattice structure than Nb-doped STO electrode.
9:00 AM		B1-3-5 Optical Emission Spectroscopy of Radio Frequency PVD Process Related to the AlN Film Stechiometry and Deposition Rate Jorge Acosta (ITESM-CEM, Mexico); Elizabeth Bauer-Grosse (Institut Jean Lamour, France); Valerie Brien, Philipe Pigeat, Robert Hugon (lpmi.uhp-nancy, France) Spectra of the mixture Ar-N2 plasma have been obtained for different N2 flows, maintaining Ar flow constant. Evolutions of Al, NI and Ar peaks have been analyzed in terms of species density finding three different regions. Peak ratios IAl/IAr; INI/IAr and IAr 750nm /IAr 811 nm have been computed in order to explain the plasma conditions for the three regions in terms of the species densities ratio and electron temperature. Seven AlN films have been prepared for different N2 flows, correlating the stechiometry films and deposition rate to the three regions I, II and III of the Ar peak 811 nm of the spectra from Ar-N2 mixture plasma. Region I was found a sub-stechiometric AlN film, regions II and III correspond to the reactive process. Region III presents a decrement of the deposition rate.