Microgrooves were fabricated on aluminum surfaces using anodizing, laser irradiation, and electrochemical etching. Aluminum specimens covered with porous type oxide films were irradiated with a pulsed Nd-YAG laser in distilled water to remove the anodic oxide film. The electrochemical etching of the laser-irradiated specimen in NaCl solution caused the formation of grooves with rough surfaces, while the electrochemical etching in CH3COOH/HClO4 solution caused the formation of grooves with flat surfaces. The width and depth of the grooves increased with electrochemical etching time. Mesh-like micro-patterns with 70μm line width and 30μm line depth were fabricated on aluminum surfaces by consecutive processes of anodizing, laser irradiation, and electrochemical etching.
We have developed an environmentally safe solvent for removing ashing residue of photo resist used in the production process of devices with copper wires and low-dielectric interlayers (Low-k). The inhibition of corrosion of the copper wires is very important for these devices, and then benzotriazole (BTA) has been mainly used as a corrosion inhibitor in current removers used in the process. However, BTA has a large environmental impact because it creates mutagenicity and biodegrades poorly. We have investigated typical natural heterocyclic nitrogen compounds to replace BTA. As a result, adenine, one of the safe compounds in living organisms, was found to effectively inhibit copper corrosion by forming a thin film on copper surface. Moreover, to control deterioration in Low-k films with low chemical resistance, we replaced a part of amino alcohol in the solvent with tetrahydrofurfuryl alcohol (THFA), which easily dissolves in water and controls the deterioration of Low-k films. The resulting remover, composed of adenine, 2-methyl-aminoethanol, THFA, lactic acid, and water, not only effectively removes the ashing residue from copper/Low-k devices, but also greatly reduces the environmental impact because it is composed of safe and biodegradable compounds.
To evaluate the adhesion property of an electrodeposited film quantitatively, Ni electrodeposition from a sulfamate solution was conducted on the joint of Al or Cu cylindrical rotating electrodes at 0.2 to 3kA/m2. The cylindrical electrodes were jointed by the deposited film. It was found that the adhesion property was evaluated quantitatively by the maximum tensile strength required to peel off the deposited film. The adhesion of the Ni deposited on the Al and the Cu at various current densities was investigated using this method. With increasing current density, the adhesion decreased on the Al, but on the contrary, increased on the Cu. It is suggested that the internal stress of the deposited Ni and the epitaxy between the Ni and the Cu each have a great influence on the adhesion on the Al and Cu substrates. The form of the cylindrical electrodes was also discussed to decrease the maximum tensile strength required to peel off the deposited film.