論文
水膜チャックの開発（第1報）
―メニスカス力による吸着力と反り矯正―
2017 年 83 巻 3 号 p. 275-280
詳細
2017 年 83 巻 3 号 p. 275-280
Silicon wafers for fabricating IC cards and smartphones must be less than a few tens of microns in thickness. After the wafer is thinned by backgrinding, the damaged layer is removed by chemical mechanical polishing (CMP) and dry polishing. A porous vacuum chuck is typically used to fix the wafer during machining. However, it is difficult to completely clean the porous chuck and to flatten a concave wafer with large warpage. To solve these problems, a water-film chuck is proposed. This chuck has a thin water film between the back surface of a wafer and the surface of the chuck. This paper describes the flattening characteristics of the water-film chuck. It was clarified that a quartz glass wafer 1.2 mm thick that has warpage of a few-hundred microns can be flattened to less than 10 μm over time. Then, a backgrinding silicon wafer with 1 mm warpage was flattened instantly below 20 μm by applying a fine water mist. In addition, the lateral restraint force per unit area was found to be over 10 kPa for a water-film thickness of less than 0.5 μm. Therefore, the water-film chuck can be used for not only wafer transfer but also grinding or light-load polishing.
