Plasma Etching of Thick BCB Polymer Films for Flip Chip Bonding of Hybrid Compound Semiconductor-Silicon Devices
J. Almerico, S. Ross, P. Werbaneth
J. Yang and P. Garrou
The Dow Chemical Company,
Keywords: Plasma Etch, Flip Chip Packaging, Hybridization
Thick polymer dielectric films are highly sought after in emerging applications such as the integration of passive components directly over silicon wafers and the packaging of compound semiconductor, SiGe or Si devices via flip chip bonding. The dielectric materials employed in this hybrid integration range in thickness from a few of microns up to tens of microns. One of the challenges for this type of packaging scheme is plasma etching of the thick polymer film with commercially acceptable equipment and high etch rates.
In this paper, we present results of a preliminary study of plasma etching thick BCB polymer films using a diode plasma etch system, with an emphasis on the etch rate of BCB etch as a function of gas mixture chemistry, RF power and pressure. Through this study we were able to find an etch process window which resulted in fairly high etch rates free of post-etch residues with the sloped etch profile which is desired for this hybrid integration or packaging.