Example Megasonic Enhanced Photoresist Strip with DiO3

Dissolved ozone in DI water (DIO3) provides an effective replacement for Piranha (H2SO4, H2O2) cleans. The fundamental chemistry of ozone-based cleaning is a result of direct and indirect reactions to ozone and oxygen radicals (radical pathway). Due to its high oxidation rate, the radical pathway can accelerate the reaction. Megasonic energy promotes the radical pathway. Simultaneously, the creation of turbulence inside the boundary layer increases the available ozone near the surface.

A study by D. Dussault of ProSys, and Jens Fittkau and Christiane Gottschalk of ASTeX GmbH, shows that the combination of DIO3 and a uniform Megasonic energy field in a conventional single wafer spinner significantly increases the strip-rate of various positive PR coatings, compared with DIO3 alone.
They measured improvements in strip-rate of over 65% (figure 5). Variations in spin speed (rpm), flow rate (L/min), and megasonic dosage (W/cm2) resulted in significant effects on the
measured strip-rate.

The POLOS Advanced 200 Series allows for ±0.1 rpm** spin speed accuracy. The user can easily program a speed of up to 12,000 rpm in 1 rpm step increments. Up to 6 dispense lines can be controlled automatically.

** Measured without substrate. Limitations may apply depending on the chuck used, and the substrate specifications.