To fabricate a Si nanohole array, a Ag dot array was patterned on Si using nanolithography with self-assembled polystyrene nanoparticles as a mask, followed by Ag-catalytic etching. The Ag dots were triangular, approximately 80 nm on a side. The nanoholes had an approximately 60-nm-diameter circular cross-section. The nanohole depth was 2-3 μm. The Si nanoholes were filled with Cu by supercritical fluid chemical deposition using bis (diisobutylmethanate) copper (Cu(dibm)2) as a precursor.
A photochemical process was applied to form an active surface layer on cyclo-olefine polymer (COP) for improved immobilization of palladium. A Xe excimer lamp irradiating vacuum ultraviolet (VUV) light of 172 nm wavelength was used as a light source for surface modification. COP samples placed in dry air with atmospheric pressure were irradiated with VUV light. Because of the dissociative excitation of oxygen molecules, atomic oxygen species were generated along with ozone molecules formed through the following chemical reactions of the oxygen atoms. These active oxygen species served as oxidants for COP surface modification. Based on VUV photochemistry assisted with oxygen, known as the oxygen-amplified VUV process, an oxidized COP layer with thickness of several tens of nanometers was formed on each COP sample. The layer, which contained highly concentrated hydrophilic functional groups such as -OH, -CHO, and -COOH, functioned as an adsorbing site for palladium catalysts. Consequently, this technique has been found to be effective as a pre-treatment of Ni-P electroless plating. Electroless Ni films with sufficient adhesion to pass the cross-cut tape test were deposited on the VUV-modified COP substrates. Direct patterning without photolithography has been demonstrated for fabricated Ni micropatterns.
A AgNO3 solution and a Sn(II)-citrate complex solution were mixed to prepare Ag nanoparticle colloidal solutions. Their nanoparticles had a core-shell structure comprising a metallic Ag core surrounded by a SnO2 shell. The Ag nanoparticles were adsorbed onto epoxy substrates conditioned with either a cationic surfactant solution of stearyl trimethyl ammonium chloride (STAC) or a concentrated solution of cationic polyelectrolyte, poly(diallyldimethylammonium chloride) (PDDA). These conditioners were strongly adsorbed, making the surface charge positive, thereby enhancing the electrostatic adsorption of the negatively charged Ag nanoparticles. The citrate acceleration of the adsorbed Ag nanoparticles increased the Ag/Sn ratio of the adsorbent by dissolving the SnO2 shell of the nanoparticles. Electroless Cu deposition was started at the epoxy substrates catalyzed with Ag nanoparticles. The citrate acceleration process increased the deposition rate of the electroless Cu plating at the initial stage by increasing the Cu nucleation rate.
This study investigated pretreatment for PVD coating onto cold working die steel corresponding to SKD11. The roughness and height of the carbide of the SKD11 surface increased concomitantly with increasing etching times by both Cr and Ar ion bombardment. The CrN coating adhesion onto the SKD11 changes to the worth, when the carbide thickness was greater than 150 nm. Electron beam irradiation of the SKD11 surface produced about 5-μm-thick melted layers having a smooth surface and improved the CrN adhesion. Furthermore, the corrosion resistance of the CrN coated onto the SKD11 improved after electron beam irradiation.
For the direct electroless deposition of adhesive metal films on Si substrates, we have developed a surface-activation process that forms metal nanorods in Si using electroless displacement metal nanoparticle deposition, metal-nanoparticle-assisted HF etching of Si, and autocatalytic electroless Ni deposition. The metal film adhesion increases with the metal nanorod length.
To shorten the production time of a through silicon via (TSV) in three-dimensional (3D) large scale integrated circuit (LSI), an in-filling technique of conductive materials was developed using a dispersion solution. The solution, containing a composite of conducting polymer (polypyrrole) and metal silver, was put into vertical holes of the silicon wafer within one minute and then solidified to form the composite.