Removal of silicon from the backside of a wafer yields a thinner IC for thinner packaging. As wafers become larger (300mm) and subsequently thicker, removing backside silicon without stressing the wafer is increasingly important.
There are two methods of “thinning” the silicon to an acceptable thickness. Back lapping uses an abrasive material, usually aluminum oxide, mixed with water and a lapping additive that functions as a detergent, a corrosion inhibitor and a lubricant. The lapping additive evenly disperses the abrasive and can take the form of a suspension-type additive or a non-suspension-type additive.
Back grinding performs the same function as back lapping but uses a fixed diamond-abrasive grinding wheel and a coolant to cool the wheel and wafer. Although water can be used as a coolant, advanced systems utilize specialized grinding coolants, which keep expensive grinding wheels free cutting and clean for extended wheel life. These grinding coolants also keep the chuck and wafer clean and free of debris for fewer defects and less breakage due to fixturing problems.
IDI manufactures a specialized lapping and grinding fluid that is widely used by the industry’s most sophisticated manufacturers to ensure high volume, high yield results.