Hajime Kuwahara

Study of Deposition Process in Modulated RF Silane Plasma

The influences of plasma parameters on the deposition of a-Si:H film and particle growth have been studied with silane discharge using amplitude-modulated RF methods. Plasma parameters have been measured with the Langmuir probe system and optical emission spectrometer. Behaviors and generation processes of particles have been observed by the laser scattering method. The deposited thin film has been characterized by various techniques such as Fourier-transform infrared (FT-IR) spectrometry, ESR and the constant photocurrent method (CPM). High deposition rate with low particle density as well as high film quality has been realized for a-Si:H film by amplitude-modulated RF methods.

Preparation of Al2O3 films by a new CVD process combining plasma and accelerated ion beams

Abstract We have developed a new p-CVD process which incorporates accelerated ions in order to produce new functional materials which have multiple structures not available when using other processes. Aluminium oxide films deposited on the nickel based superalloy (INCONEL718) by p-CVD combined with simultaneous N 2 + (accelerated to 10 keV) irradiation are polycrystalline and have very smooth surfaces and show superior adhesion compared to conventional plasma CVD layers.

Titanium coating of the inner of a 1 m long narrow tube by double-ended anode coaxial magnetron-pulsed plasmas

In order to reveal the potential of a coaxial magnetron-pulsed plasma (CMPP) reactor for the deposition of thin films on the internal walls of narrow tubes, discharge characteristics and an extended-anode effect were investigated. The extended-anode effect is quite unique in CMPP, and appears due to the deposition of a conductive film onto the surface of an insulator. Three discharge regions corresponding to a plasma breakdown, a steady state and an afterglow were observed and characterized. The breakdown region was extremely dependent on the repetition frequency of the pulsed voltage. Titanium thin films were sputter-deposited onto the inner surface of a narrow glass tube (1000 mm long and 8 mm inner diameter) using double-ended anode coaxial magnetron-pulsed plasmas (DCMPP), to which CMPP was applied for the internal coating of narrow tubes with high aspect ratios of length to inner diameter.

Properties of a-Si:H Film Deposited by Amplitude-Modulated RF Plasma Chemical Vapour Deposition for Thin Film Transistor.

The method of amplitude-modulated RF plasma enhanced chemical vapour deposition (p-CVD) has been used to deposit the a-Si:H film. Various properties of the deposited a-Si:H film such as uniformity of thickness, stress of film and hydrogen concentration in the film are studied. These film properties are improved in the case of amplitude-modulated RF p-CVD compared with the CW case, particularly at the high deposition rate. Further investigation has been carried out by constructing a bottom gate thin film transistor (TFT) device without an etch stop layer. The measured electron mobility and threshold voltage, are also improved up to the deposition rate of 32 nm/min by the method of amplitude modulated RF p-CVD at the modulation frequency of 68 kHz.

EXTENDED ANODE EFFECT IN COAXIAL MAGNETRON PULSED PLASMAS FOR COATING THE INSIDE SURFACE OF NARROW TUBES

In order to coat functional thin films onto the inside surface of narrow tubes, a coaxial magnetron pulsed plasma (CMPP) device has been developed. The feature of this device is that deposited conductive films play the role of an anode. Consequently, plasmas are generated away from the anode located at one end of the tube and the distribution of film thickness widens with increasing deposition time. This is called the extended anode effect. The shifting velocity of the main position for plasma generation was dependent on the properties of the target materials. The shifting velocity increased with sputtering yield and decreased with the electrical resistivity of target materials.

Ln-Ba-Cu-O Thin Film Deposited by Ion Beam Sputtering

We have successfully fabricated the high quality yttrium barium copper oxide ( YBCO ) thin film with Tco=88K and ytterbium barium copper oxide ( YbBCO ) film with Tco =77K by the method of Ion Beam Sputtering. The as-grown films ( YBCO and YbBCO ) on the MgO substrate showed superconductive transition up to 54 K. To improve the superconductivity, heat treatment was necessary at around 800 C for YbBCO film and around 900 C for YBCO film in the oxygen atmosphere. The opitimized conditions for heat treatment depended on substrate material and film composition.