Here is the abstract you requested from the IMAPS_2012 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|The Truth About Scallops and cost of deep silicon etch|
|Keywords: etch, TSV , process|
|The truth about scallops and the cost of deep silicon etch. Since the beginning of accelerated TSV development, the perception of Bosch process has been high cost with technical fill challenges due to large scallop profile on via side wall. Advances in gas delivery modulation and polymer removal have enabled near zero scallop profile and enabled 50% year over year improvements in silicon etch rates. The formation of sidewall scallops is due to inherent nature of the Bosch process, which uses alternating deposition and etch steps to create deep silicon vias. The size and depth of these scallops can be controlled by modulating gas flows, step times, polymer removal and isotropic etch. Scallops can also be reduced by virtue of via depth – the deeper the via, the previously formed scallops will get ‘smoothed’ away. A balance must be struck between sidewall protection and undercut: too much polymer will protect the scallops from getting smoothed and too little polymer will erode the sidewall and form an undercut.|
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