Silicon wafer backside thinning with mechanical and chemical method for better mechanical property

A cheaper alternative method of Silicon wafer backside grinding and thinning, including the mechanical rough backside grinding and chemical polish was studied and conducted in JCAP (Jiangyin Changdian Advanced Package Co., LTD.) to respond to the trend of thinner chip for semi-conduct package. This study mainly focused on using different etchant to etch Silicon to release the stress caused by the mechanical grinding, in addition micro-crack from the mechanical back-grinding can be eliminated, the stress can increase the operational difficulty of thin wafer in the semiconductor assembly packaging process, such as SRD (Spin Rinse Dryer), transfer and handle. HNA(hydrofluoric and nitric diluted by acetic) was chosen as the etchant for silicon etching, because it is perfect and economical. For different application, there are different etch depths. After silicon etching, the wafer was cleaned with physical or chemical way, depending on the product property and function. Using this way, JCAP can achieve thinner than 100 mu m in 6 inches wafer and can be back metallized.