Dicing Tape Performance in a Plasma Dicing Environment

Abstract

Plasma dicing, as a means of isolating individual integrated circuits from within a fully processed semiconductor substrate, is still an emerging technology but is now considered the latest step in the evolution in device singulation. With the trend towards smaller, thinner more robust devices, many chip manufacturers are considering, or already switching, to a plasma dicing approach.[1, 2] The high aspect ratio, deep reactive ion etching of silicon using a Bosch process, leverages some distinct advantages over the more physical methods of device singulation. [3] Although the more established methods of diamond blade saw dicing, various laser based approaches or laser/mechanical hybrid dicing techniques, all introduce an element of heat and in some cases water for cooling purposes, they do not expose dicing tape to the unique conditions within high vacuum plasma. This work investigates how the properties of both dicing tape and adhesive are affected when exposed to the environment of a plasma dicing process used in the semiconductor industry. A preliminary fitness test utilising an aggressive exothermic etching regime was used to establish the compatibility of a range of standard Lintec Adwill dicing tapes. In essence, a measure of base film thermal conductivity and how quickly some of the lower molecular weight volatile components of base film and adhesive materials are boiled off or ‘out-gassed’. Polyvinyl Chloride (PVC) tapes performed less well than Polyethylene terephthalate (PET) tapes and some of the Polyolefin (PO) tapes exhibited the greatest resilience. A design of experiments to measure changes in tensile strength, elongation and adhesive properties were carried out to assess the performance of plasma dicing on PO low adhesion tape. Figure 2 shows that the samples exposed to an SF6 plasma impacted the tape elongation and tensile strength properties. Typically the stretch required for PnP is in the range 1–10 % showing that the plasma dicing does not impact the overall performance of the tape. Further tests employing a die pick-up force measurement system to compare saw diced die with that of plasma diced die, proved the feasibility of this technology. Figure 3 shows that pick-up force measured on plasma diced dies is comparable with saw diced dies.