A method for copper deposition on glass and ceramics was investigated by direct plating on 20-30 nm thick copper inclusive titanium oxide films formed on the substrate surface. The copper inclusive titanium oxide film functioned as an adhesion layer and as a catalyst for autocatalytic copper deposition. Copper inclusive titanium oxide films were formed by pyrolysis of solution deposited 1-hydroxy phenyl ketone titanium-copper complex films. After deposition of electroless copper seed layers, 15-20 μm thick electrolytic copper films were formed, where upon thermal treatment up to 0.5 kN/m adhesion strength was attained on borosilicate glass. This process enabled electroless copper plating without the use of palladium as a catalyst on non-roughened smooth glass or ceramic substrate surfaces. The copper-titanium oxide adhesion layers were characterized and cross-sectional transmission electron microscopy illustrated the adhesion mechanism and catalyst structure. Despite poor thermal conductivity, due to properties such as transparency, smooth surface, chemical and thermal stability, coefficient of thermal resistance, dielectric constant, electrical insulation and physical strength, glass has gained attention an electronic substrate material.1-3 Two examples are in 2.5 D/3 D electronic device and RF module packaging. [4][5][6][7] In addition to these properties, abundance and availability in a wide range of shape and size make glass an attractive economic substitute for silicon in interposers. [4][5][6][7] Development of through substrate interconnect via hole formation technology for glass has progressed however, metallization technology relies on vacuum deposition, the silver mirror reaction or surface roughening followed by electroless plating for conductive seed layer formation. [8][9][10][11] Using sputtered Cu, Ti/Cu or Cr base layers, relatively high adhesion strength has been attained.12-14 However, dry processes have productivity limiting disadvantages such as size restriction, need for expensive equipment and high running cost. Therefore, economic wet methods have been studied as an alternative. In direct electroless plating methods, adhesion between the glass and the plated films has been accomplished by etching the glass surface with hydrofluoric acid, but with the sacrifice of its original transparency and smoothness. [15][16] Furthermore, employment of expensive palladium catalyst also introduces the need for a palladium removal procedure in order to prevent migration and short circuits that lead to poor device reliability. [17][18][19] Solution processed adhesion layers for direct electroless plating on glass have been demonstrated where a few tens of nanometer thick Pd-NiO, 20 Pd grafted TiO 2 , 21 or Pd-SnO 2 22 films served as catalytic anchor layers. Based on those results, the method outlined in Figure 1 for direct electroless copper plating on the substrate was investigated, where the catalytic anchor layer consisting of copper and titanium oxides was formed by pyrolysis of a metal complex film ...

A method for direct formation of patterned metal film on glass without resist use or etching was investigated. Palladium, which functions as an initiation catalyst for auto-catalytic metal deposition reactions, was selectively adsorbed onto solution processed nano-porous titanium oxide films on glass from an ionic palladium solution. After selective palladium catalyst grafting onto the titanium oxide, exposure of the films to an electroless nickel, copper or gold plating solution resulted in metal deposition selectively on the titanium oxide surface. Photo-active titanium complex films were photo-patterned then pyrolyzed to give the respective pattern preserved titanium oxide films that could then be selectively plated. Correlations between titanium oxide film characteristic and palladium adsorption were analyzed by ellipsometry and inductively coupled plasma mass spectroscopy. Cross section observation of metalized glass showed penetration of palladium catalyst into and elucidated the structure of plated metal on the patterned titanium oxide films.

No abstract

セミアディティブプロセスによる平滑ガラス基板上への回路形成 岡部 恭平 236-0004)Circuit formation by a semi-additive process of copper films on glass was investigated. Copper films were produced on a glass substrate by direct electroless copper plating on a 20-30-nm-thick copper inclusive titanium oxide catalytic adhesion layer formed earlier on the glass substrate surface using a sol-gel method. After seed layer deposition, galvanic deposition thickened the copper film to 10 μm. Formation of L / S ＝ 50/50 μm to 200/200 μm copper circuit patterns on the glass substrate was then demonstrated, where adhesion was maintained throughout the process. The copper-inclusive titanium oxide adhesion layer was removed completely from the glass substrate surface without notably altering the glass surface morphology using a sodium hydroxide 100 g / L, trisodium citrate 5 g / L solution etching solution. Furthermore, in post electroless Ni-P plating, extraneous deposition was prevented by complete removal of the titanium oxide adhesion layer.