Vol. 61 No. 1Material Science and Technology of Japan, 61（2024）23～27

23

Regular Paper
Solvent Soluble Ti4+ and Si4+ Complex Solutions for Titanium Silicon
Oxide Layer Formation on Glass for Increasing Copper Plating
Adhesion StrengthAjay DEVRUKHKAR1,2,*, Christopher E.J. CORDENIER1,2,3, Yasushi UMEDA2, Hideo
HONMA2 and Joo-Hyong NOH1,2
1Graduate school of Engineering, Kanto Gakuin University, Yokohama, 236-8501, Japan
2Materials and Surface Engineering Research Institute, Kanto Gakuin University, Yokohama 236-8501,

Japan
3Raresynthesis Co. Int. Yokohama 236-0057, JapanReceived Oct. 25, 2023; accepted Jan. 17, 2024
Abstract
Due to its industrial potentials, copper plating on glass has been explored through a variety of methods. The formation of a Cu film on aglass substrate is considered a fundamental technology in substrate-related industries; however, it has slow progress. The reason is pureCu cannot adhere on to glass substrates directly, usually pre-depositing of an adhesion layer, such as Cr, Ti, or TiW, is required. In thisstudy, an organic solution primarily composed of ethyl lactate and γ-butyrolactone, containing titanium (Ti) and silicon (Si) complexes,
was used to coat borosilicate glass. Once coated, annealing the coated substrates resulted in the formation of a mixed Ti and Si oxide layer,
15~30 nm thick, depending on the coating conditions. The formed layer was able to adsorb Pd ions upon submersion in an arginine-Pdcomplex solution, catalyzing an electroless copper deposition reaction. A 100~300 nm thick electroless copper film was formed on theTi/Si layers. The electroless Cu film was later dried, and at last the copper layer was plated to 15~30 µm by electroplating. Upon annealing
a second time, the Ti, Si and Cu reacted to form adhesive chemical bonds between the three metals, giving the copper coated glass
substrates with an average 90º vertical copper film peel strength of 7 N/cm, while maintaining a nanometer-scale smooth interface. Thissuggests Ti and Si were significantly responsible for the adhesion strength, compared to layers containing only Ti. The presence Si content
generally resulted in higher adhesion strength than only Ti.
Keywords: Glass plating, Ti-Si solution, liquid processing, copper1.

Introduction

films with some degree of adhesion post-thermal treatment [2].

Dielectric materials have been of great interest in recent years

Silver has been demonstrated to activate glass surfaces in a single-due to their potential application in novel magnetic, catalytic,

step method prior to conventional electroless plating [3], zincelectronic, and nonlinear optical devices including multi-chipoxide has also been found to serve as an adhesion layer, yielding

module packaging and printed circuit board manufacturing. Duereasonable results [4]. In addition, photopatterning of zinc

to its industrial potentials, various methods have been reported forcompound has been demonstrated [5]. Regarding the metallizationcopper plating on glass [1]. The formation of Cu film on a glassof glass with copper, the use of Ti complex solutions in organic

substrate is considered a fundamental method in substrate-related

solvent solutions has been accomplished [6]. The inclusion ofindustries, though progress has been slow. The reason is, pure Cu

copper in the titanium solutions was found to become catalyticallycannot adhere to glass substrates directly, usually glass surface

active upon reduction in borohydride solution, enabling copper

modification and an adhesive layer like Cr, Ti, or TiW is required

plating without requiring palladium as a catalyst, where highbetween glass and Cu for strong adhesion. Lee et. al appliedadhesion was attained post-thermal treatment [7]. Furthermore,

copper paste directly on to glass substrate, resulting in thin copper

direct patterning via photolithography using photoactive Ti-*Corresponding author: (d20J8005@kanto-gakuin.ac.jp)(23)