Effect of Surface Treatment on the Mechanical Strength of Ultrasonically Bonded Chip on Copper-Coated Glass for Ultra-Fine Pitch Application in Microelectronics

摘要

This study was focused on the effect of surface treatment on the mechanical strength of ultrasonically bonded copper chips on copper-coated glass. The plasma treatment was performed with two different gases, either N_2 + O_2, or N_2 + H_2, for treatment times up to 18s. Wet treatment was also carried out with 5 vol % H_2SO_4. Surface analysis was carried out after the treatment using Auger electron spectroscopy (AES) and it was found that treatment conditions greatly affected the joint strength. Wet cleaning with 5 vol% H_2SO_4 effectively removed oxides from the Cu surface, while addition of O_2 gas into N_2 gas plasma was good for removing carbides. The treatment conditions greatly affected the removal of contaminants on the Cu surface and the bondability between Cu bumps and Cu-coated glass substrates.