Temporary Non-Etching Adhesion Promotion System for Dry Film Applications

Within the Semi Additive Process (SAP) it is common for the Process´s Copper seed layer to be only chemically cleaned before dry film lamination and imaging. While this has been historically acceptable, as imaging requirements increase, it is now beginning to reach its limitations. Two methods to resolve this exist; the one being pursued by dry film manufacturers is to increase the flow and adhesion properties of the dry films themselves, while the other solution is to treat the available Copper surface so that its own adhesive properties increase. Atotech´s ResistAssist^reg IC process is a novel non-etching chemistry that actively increases dry film adhesion without any effect on track geometry or subsequent processing steps. This paper discusses the development and latest results achieved with this process. Test methods centre on adhesion of fine line dry films to surfaces treated with the ResistAssist^reg IC chemistry, and then subjected to further tape testing. For comparison, the relative performance to surfaces treated with acid cleaning only is also reported. The summary of this work is that this novel approach offers yield improvements over a current acid clean process, or potentially an increase in fine line capability with the same dry film.