Setup Surface Cleaning process
After understanding the surface contaminant and detergent selection, now is the time for us to setup a wet surface cleaning process. CMP process for wafer and hard disc substrate is one of the highly demanding processes and the subsequence surface cleaning process does play an importance role in overall yield. The wet surface cleaning process is critical as it requires removing the contaminant left over on the surface. The contaminant may come from the polishing sludge, CMP slurry and environment.
Many details need to be given in order to identify the contaminant source before establishing a reliable surface cleaning process. In most cases, wet cleaning process is preferred. There are several areas cleaning field engineer should consider.
Detergent use in wet surface cleaning process
Surface cleaning detergent selection is very important at this stage. Not all surface cleaning detergent performs the same for wet surface cleaning process. After identifying the surface cleaning detergent, cleaning field engineer should carry out series of experiments to evaluate the process window and identify the optimize concentration.
PVA sponge roller use for wet cleaning process
In most case, scrubbing is one of the effecting actions for wet surface cleaning.
And PVA sponge roller is the material commonly use in the wet surface cleaning process. The PVA sponge roller is soft in nature which not causing scratches on the substrate surface and the porous structure also becomes the waterway for detergent flow on the substrate surface.
PVA sponge roller sound simplicity at first glance, however through out our involvement in cleaning process, DST is able to supply various design of PVA sponge roller for dedicate wet surface cleaning process. We could design the difference surface structure such as nodular and spline roller, on the other hand, DST also design difference pore size for dedicate contaminant.
Scrubbing time for wet surface cleaning process
Longer the scrubbing time, better the result. This sentence is true in certain extend. Cleaning field engineer should examine the scrubbing time to allow sufficient time for removing the contaminant from cleaning substrate. In practical case, cleaning field engineer could perform several test of difference scrubbing time to find the optimum case.
Re-visit Surface Cleaning Process
Cleaning field engineer is required to re-visit the cleaning process for continual improvement. The surface cleaning monitoring system comes into roles at this moment. Field cleaning engineer should evaluate the monitoring data and identify the common phenomenon or pattern in order to identify the source of contaminant.
Cleaning field engineer should also audit the wet surface cleaning process with razor-sharp eagle eyes. Minor change of process setup should identify for improvement.
DST Technology is having more than 10 years experience in wet surface cleaning process which we are confident to bring benefit to customer and industry. Feel free to contact DST for further discussion.