Types of silicon wafers
Silicon wafers are expensive enough that it makes great sense to reuse them. You are even able to reclaim all of your used wafers several times now, thanks to a process developed back in 1974 for reclaiming wafers. The companies that do this work are able to turn out a few thousand wafers every working day.
This means they can turn around reused wafers in only a day. Thanks to the large scale reclamation of these silicon wafers, it is highly cost effective to reclaim your spent wafer inventory. There are a number of steps involved with reclaiming and stripping silicon wafers discussed below.
Incoming Wafers Receipt and Inspection
The wafers have to be acquired from customers to begin the process. The firm will first inventory all wafers. They put together a report of conditions of the wafers before the process begins.
Presorting, Stripping, and Etching
The next steps start with sorting the wafers so that their film can be removed. Multilayered wafers will receive stripping schedules. All wafers will next be sorted into like groups according to their thickness. Stripping and etching involves a chemical process. This effectively removes all present films and patterns from the wafers.
Quality Assurance and Silicon Wafer Polishing
At this stage in the process, the wafers become inspected for quality and sorted. They are then ready for the critical step of polishing. Polishing employs cutting edged equipment in order to polish the wafers with a surface that is prime test. The wafer reclamation company assures that surface specs will meet minimal quality standards. The polishing technology is so precise that a mere several microns are all that is removed.
Clean Spin/Rinse/Dry and Visual Inspection
All wafers are finally cleaned utilizing the SC1 or SC2 procedures. This removes all particles. All wafers then undergo 100 percent visual inspection.
Final Inspection and Quality Assurance
The last step involves using the KLA 6400 to inspect all wafers to guarantee the particle count meets specifications. All wafers go through a final inspection and become sorted. Following this final inspection they are vacuum sealed and delivered the same day.
Thanks to the efficiency and turn around times in reclaiming used silicon wafers, it is highly practical to reuse them. Gone are the days of having to replace expensive wafers every so often.