From Feedstock to Wafers

After solidification, the ingots are shaped using diamond-coated band saws or wires in an abrasive medium in order to have square multicrystalline or pseudosquare rounded angle monocrystalline blocks. This process removes the outer parts of the ingots, generally out of specification for dimensions and with some contamination from the containers or the furnaces. 

The square or pseudo-square blocks are cut into thin wafers using multi-wire saws, a technique which was developed specifically for PV and which is now common in the semiconductor industry also. A great deal of progress has been made with equipment and process control aspects and in introducing reduced diameter wires several hundred kilometers long for reduced kerf loss. 

This step is evidently not required for ribbons, apart from edge trimming and cutting the wafers from the sheets. This is considered to be a major advantage over ingot technology in terms of costs. 

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