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ecoSplitC™
Description
Problem:
Solar wafers from pre-cleaned wet wafer stacks direct from the wire saw need to be separated from the sawn stack for the subsequent cleaning process. The wafers are held together by fluid retention of wire saw coolant and waste silicon carbide making them difficult to manually separate without a compromise of speed against breakage.
Solution:
The patented singulator module offers a solution for both multi-crystalline and mono-crystalline wafers and is user configured for 125, 156 and 210mm wafers over a very short changeover time. A spraying system ensures wafers are kept wet throughout separation and during transportation through the system. There is also an automatic rejection lane for wafers out of thickness tolerance, which enables continuous operation. The system has been tested successfully with wafers down to 150μm, thinner wafers are possible subject to evaluation, wafer quality and wire saw tolerances.
Versions:
The system is flexible to fit customer needs and is offered in two basic configurations. For Inline processing, the ecoSplit-I offers maximum throughput over 5-6 output lanes to feed the Inline cleaner directly. Whilst ‘batch’ ecoSplit-C offers loading of separated wafers direct to the wafer carrier. Both systems are available in combination or are customized to meet throughput requirements of the customer.
Innovative Aspect:
The task was to find an automated method of separation that would not damage wafers and risk devaluation. In order to achieve this, wafers need to be kept wet and ‘teased’ apart mechanically using a set of synchronized push rollers with a special material and profile. These rollers push the bottom wafer from a short stack (approx. 150) through a special fine (micro) adjustment gate. This is best described as analogous to like dealing the bottom card from a deck of cards. These rollers must have a high enough coefficient of friction to grip the surface of the bottom wafer and must not mark or damage the surface of the wafer in any way. The system must also be able to handle broken wafers and thicknesses out of tolerance due to wire saw problems. The first revision of this ‘patented’ separation technique was developed in 2005. Now on its 3rd revision, together with the subsequent wafer handling automation after separation, the system provides fast and safe wafer handling to carriers for batch processing, or direct to multiple output tracks for inline processing.
Benefits
The market cost per wafer is dropping, additionally wafer thicknesses are getting smaller and breakages are increasing through manual wafer handling, consequently manufacturers need to compensate through the higher production yields of automation. The ecoSplit is a separation system that offers a very short ROI and a low COO by providing a totally safe, proven, and fast mechanical method of separating wafers into process carriers for batch processing; or to 5-6 output lanes for inline processing. The benefits are quite clear; firstly to provide a higher throughput of wafers per operator, and secondly to provide a lower breakage rate per operator with a Return of Investment of less than 1 year based on a very conservative and cautious breakage rate. On higher breakage rates, ROI can be within a few months.
