Previously, wafer blocks were prewashed only in so-called batch processes and subsequently debonded with acid i.e. the glass carrier detached from the silicon. Narrow kerfs, and thin cutting wires made the cleaning task with spray heads increasingly more difficult and costly.
In close mutual cooperation with the Swiss company N. Bucher AG - inventor and distributor of the ceramic carrier plate, which replaces the glass plate in wire sawing - the Schmid Group has developed a completely new inline cleaning concept.
The sawn wafer block is moved inline on a carrier through the system. The cleaning process takes place directly in the cutting gap with the aid of special ceramic carrier plates. In addition to an increased yield of wafers in this process step, the partners Schmid and Bucher are counting on substantial improvements with the bonding, separation and final cleaning processes.
A pilot system of the wafer pre-cleaning process was on display at the 24th EU PVSEC in Hamburg. This process line will be operated in the plant of a leading European wafer manufacturer by Autumn 2009 already.
All persons involved in the development of this system expect vast changes in the cleaning process, not only with wafering, but also in applications far beyond this. Initial results show promise of improved efficiency in the cell process, because the cleaning process is carried out very evenly over the entire surface.