Abstract

Electroless copper deposition is used in the fabrication of integrated circuit (IC) interconnections, micro-electro-mechanical systems (MEMS) devices and printed circuit board (PCBs). In order to meet the long term usage of chemical bath for electroless deposition, an eco-friendly copper methane sulphonate (CuMS) was used to prepare the chemical bath for Cu deposit. The deposition parameters such as temperature, pH, Cu ion concentration and para-formaldehyde concentration were optimized at 28 ^oC with 3 g/L of CuMS, 10 g/L of para-formaldehyde for the pH of 12.75. The deposition rate was increased for high concentration of Cu and para-formaldehyde in the chemical bath. Highly stable bath was achieved at 28 ^oC with 1 ppm thiourea content and produced uniform Cu film surface with larger grains. Good quality and (200) oriented Cu thin film with larger crystallite size was observed with 1 ppm thiourea added bath.

Keywords

Electroless deposition. Copper methane sulphonate, Stable bath, Saccharose, Thiourea