Cropping poly-crystalline and mono-crystalline silicon is performed to obtain a flat surface for subsequent fabrication of the silicon ingot or slab into a block of a certain dimension through the process of “squaring”.
Both cropping and squaring are abrasive sawing processes. The cropping process uses either an annular saw, an OD saw or a reciprocating saw. Each saw has a blade that is coated with industrial diamond. The blade needs to be cooled and lubricated during the process to avoid extreme heat and chipping of the silicon surface.
Squaring transforms the cropped silicon slab or ingot into measured blocks that are then mounted on silicon carbide slurry fed wire saws and transformed into individual wafers. Modern squaring is performed using saws that utilize diamond coated wire to perform the cutting action. This newer technology increases the production of squaring two times while producing less waste and cleaner wafers than traditional technology. It is important to utilize the correct coolant/lubricant for diamond wire sawing to ensure that the wire does not break and that chipping and bad surfaces are avoided.
After squaring, the silicon blocks are edge-ground, cleaned, and mounted on a traditional wire saw for wafer processing turning the blocks into individual wafers.