TSV Resist and Residue Removal

3D integration is the most active methodology for increasing device performance. The ability to create Through Silicon Vias (TSV) provides the shortest path for interconnections and will result in increased device speed and reduced package footprint. There are numerous technical papers and presentations on the etching and filling of these vias, however the process for cleaning is seldom mentioned. Historically, after reactive ion etching (RIE), cleaning is accomplished using an ashing process to remove any remaining photoresist, followed by dipping the wafer in a solution-based post etch residue remover. However, in the case of TSV formation, deep reactive ion etching (DRIE) is used to create the vias. A byproduct of this etching process is the formation of a fluorinated passivation layer, often referred to as a fluoropolymer. The fluoropolymer is not easily removed using traditional post etch residue removers, thus creating the opportunity for new and improved formulations and processes for its removal. This paper will describe a robust cleaning process for one step removal of both the photoresist and sidewall polymer residues from TSVs. A combination soak and high pressure spray process using Dynastrip™ AP7880™-C, coupled with a megasonic final rinse provides clean results for high aspect ratio vias. SEM, EDX and Auger analysis will illustrate the cleanliness levels achieved.