Isao Yamada

Low Temperature Graphene Film Formation with Ethane Cluster Ion Implantation

Low-temperature formation of graphene films with ethane gas cluster ion beam (GCIB) implantations were investigated. Ethane GCIBs realize both shallow carbon implantation and creation of high temperature and high pressure conditions simultaneously, which lead to reduction of substrate temperature for graphene formation. By optimization of deposition conditions, it was found that graphene like films were formed on Ni by 5 keV ethane GCIB irradiations at substrate temperature of 400 oC, which was much lower than that required for a typical CVD graphene deposition (800 - 1000 oC).

Surface Modification of PEEK with Gas Cluster Ion Beam Irradiation

In this study, we investigated surface modification of poly ether ether ketone (PEEK) with gas cluster ion beam(GCIB) irradiation. Since GCIB induces high energy density on the irradiated surface, only surface layer is physically or chemically modified without introducing damages in the bulk substrate. The contact angle of water on PEEK decreased with the acceleration voltage of O2-GCIB, which indicated the improvement of hydrophilicity.u3000This increase of hydrophilicity might be explained by increase of hydrophilic group and microstructure on PEEK surface. Preliminary experiments of cell adhesion tests on PEEK with O2-GCIB irradiation showed 25% increase of cell adhesion compared to pristine PEEK substrates.

Surface Modification and Activation with Gas Cluster Ion Beam

Gas cluster ion beam (GCIB) was used for surface activation bonding (SAB). Since GCIB modifies only near surface, low-damage surface modification and activation are expected. In this study, Cu-Cu bonding with GCIB irradiation was selected as a preliminary study. XPS and contact angle measurement showed that surface oxide on Cu was removed efficiently by oblique incidence Ar-GCIB at 20 kV. Also, sequential irradiation of GCIB at normal and oblique incidence realized smooth Cu surface. Cu-Cu bonding did not succeced without GCIB irradiation or with 5 kV Ar- GCIB irradiation. On the country, Cu-Cu bondings were realized with 10 or 20 kVAr-GCIB irradiations owing to surface oxide removal.

COMPARISON OF IRRADIATION EFFECTS BETWEEN CLUSTER AND MONOMER FOR DLC FILM DEPOSITION

Diamond-like carbon (DLC) films were formed by Ar cluster ion beam assisted vapor deposition of C 60 . To study the effects of contaminating Ar monomer ions (Ar + ) in the cluster beam on the sp 2 content, hardness, and surface morphology of the films, beams of Ar cluster ions, Ar + , and a mixture of cluster ions and Ar + were used From the near edge X-ray absorption fine structure (NEXAFS), lower sp 2 contents in films were obtained when Ar cluster ion beams were used Higher hardness and smoother surfaces were also obtained by irradiations of Ar cluster ion with higher fraction

High quality optical thin film deposition with gas cluster ion beam assisted deposition

Gas cluster ion beam assisted depositions realize ultra-low energy (several eV/atom) ion irradiations and is able to deposit high-density films without damages by energetic ions. Surface smoothing effects are fascinating characteristics of this technique.

Optical thin film deposition with O2 cluster ion beam assisted deposition

O2 gas cluster ion beam (O2-GCIB) assisted depositions were studied to form high quality Ta2O5, Nb2O5 and SiO2 films. The optimum irradiation conditions for Ta2O5 and Nb2O5 film depositions were the acceleration energy of 5 to 9keV and the cluster ion current density over 0.5{mu}A/cm2, respectively. The Nb2O5/SiO2 films deposited with O2-GCIB irradiations showed very uniform and dense structures without columnar or porous structures. Due to the significant surface smoothing effect of GCIB, the interface and top surface of Nb2O5/SiO2 multi-layer were quite flat. The interference filter deposited with O2-GCIB assist deposition was very stable and there was no shift of wavelength before and after environmental tests. As O2-GCIB is equivalently very low-energy ion beam and is able to deposit flat and dense amorphous films at low substrate temperature, it is suited to deposit multi-layered films where low-energy assisting ions are required.

NEXAFS study on the local structures of DLC thin films formed by Ar cluster ion beam assisted deposition

Near‐edge X‐ray absorption fine structure (NEXAFS) spectra were measured for the optimization of synthesis conditions on the production of diamond‐like carbon (DLC) thin films by the Ar gas cluster ion beam (GCIB) assisted deposition of fullerene. The sp2 contents of DLC films were estimated from the analysis of the peak corresponding to the transition of the excitation electron from a carbon 1s orbital to a π* orbital in the NEXAFS spectrum of the carbon K‐edge over the excitation energy range 275–320 eV. Substrate temperature and Ar cluster ion acceleration voltage in the synthesis conditions of DLC films were optimized to make the sp2 content minimum.

Formation of shallow junctions using decaborane molecular ion implantation; comparison with molecular dynamics simulation

The formation of P/sup +//N shallow junctions requires the incorporation of boron atoms at depths closer to the surface of the crystal. This is done commonly by implanting boron ions at low energies. Another approach for forming shallow junctions involves, in principle, implanting large molecular ions accelerated to higher energies but with an equivalent low energy per boron atom. Molecular ion implantation of Si using decaborane has been simulated using molecular dynamics (MD) at energies between 4 keV and 4 keV per molecule. The simulation shows local swelling resulting from individual molecular impact and hydrogen is also implanted into silicon. Decaborane was implanted at 4 keV and 7 keV at doses of 1E13 and 1E14 cm/sup -2/. Junctions with depth <600 /spl Aring/ and sheet resistance of 480 /spl Omega///spl square/ have been demonstrated.