A study has been performed to determine the viability of Potassium hydroxide (KOH) as a wet etchant to create backside vias to devices previously manufactured on thinned wafers. In order to protect frontside devices in the back end of line process, the KOH must not come in contact with the front of the wafer. A number of methods have been investigated with the advantage being in the use of a coat of black wax. This paper will present results obtained from tests with black wax as well as provide insight to the advantages and disadvantages of other protection options.
Hathorn, Michael E.
"Implementation of Backside Vias as an Alternative to Wafer Thinning,"
Journal of the Microelectronic Engineering Conference: Vol. 14
, Article 11.
Available at: http://scholarworks.rit.edu/ritamec/vol14/iss1/11