After the silicon ingot is removed from the furnace, the ends must be cut off to obtain a flat surface for subsequent fabrication. This is accomplished through the use of a cropping saw. A cropping saw is a large-diameter annular saw with an I.D. diamond-plated saw blade. During cropping, this blade must be properly lubricated, cooled and cleaned to prolong its life and assure precise results.
After cropping, the ingot is transferred to an O.D. grinding machine to precisely shape the outer diameter of the ingot into a standard wafer size of up to 300mm. During this process, it is again essential to cool, lubricate and clean the diamond grinding wheel for precise results and improved wheel life.
A notch or flat is then ground into the ingot according to its desired crystallographic orientation so that once a wafer is produced it can be properly aligned with a photomask. Called slot grinding, this is a short and simple step, but still requires the same type of lubrication and cooling as needed during cropping and O.D. grinding.
IDI manufacturers specialized coolant/lubricants developed to maximize yield in all three of these applications.