After CMP, the surface can be highly contaminated by slurry residues. Tests performed on a 3’’ silicon wafer polished with a slurry containing 50 nm colloidal silica particles demonstrated that the use of POLOS Advanced with ZTop MegPie megasonic transducer operating at around 1 MHz and combined with diluted NH4OH, produced excellent cleaning results. * Highly diluted (2%) NH4OH is used to enhance electrostatic repulsion between particles and surface (control of Zeta potential) to avoid re-deposition and re-attachment.
Our test case integrated the Polos ZTop MegPie within the POLOS Advanced 200 mm spin processor. This MegPie kit allows you to choose between 150 and 200 mm active area, and is available with a sapphire or stainless steel ZTop MegPie.
The POLOS ZTop MegPie control is integrated into the software of the POLOS Advanced, allowing servo-controlled positioning of the MegPie and control of forward power. It also monitors the reflected power, and controls the temperature alarms. The distance to the substrate is monitored with an ultrasonic sensor.
Excellent results are achieved by using the megasonic cleaner diluted with NH4OH,
* Test report available upon request.