A Comparative Study for the Backside Illumination (BSI) Technology using Bonding Wafer Cleaning Process for Advanced CMOS Image Sensor

摘要

To summarize, we have synthesized direct bonding of Si and SiO_2 surface is presented by SC-1 and diluted HF chemical. As can be seen from the results, the surfaces to be bonded are cleaned in a diluted HF solution rather than other chemical treatment. These results in a surface covered with fluorine, which is substituted by hydroxyl groups by a water rinse, resulting in a highly bondable surface under the plasma activation using N_2 and O_2 gas below 400 °C temperature, respectively. In addition, we studied the optical characteristics with optical image, contact angle, and the scanning surface potential analysis. The method is believed to have the possibility of being a useful tool for bonding steps both in micromechanical and microelectronic applications, especially for bonding of oxidized surfaces. It can be seen clearly that cleaned surface on the reduced particle and organic residue, it has treated with SC-1 and diluted HF chemical process rather than SPM and SC-2 chemical process, respectively. In order to better understand the differences between treated SC-1 for hydrophilic property and treated diluted HF for hydrophobic property in terms of surface parameters, we have undertaken their characterization by contact angle and the scanning surface potential analysis.