In planarizing a thin substrate, it has been difficult to remove warp or waviness as such substrates are forcibly deformed by conventional clamping methods. To clamp a thin substrate with no deformation, we have developed a freezing pin chuck system that fixes a thin substrate by freezing the fixation liquid on many pins. This paper describes the precision and fixing characteristics of this newly developed clamping process. The process consists of temperature control of the chuck, a spraying method to form droplets having concurrently uniform height on all pins, and a placing and fixing method that uses melting and refreezing steps so as to not impart shock on a wafer. Fixing strength in the shearing direction achieved more than 110 kPa, and the maximum deformation using the proposed clamping process achieved only 10 μm for a wafer 300 mm in diameter, 1.2 mm in thickness, and 100 μm in warp. Additionally, it is shown theoretically that the cause of slight deformation in this clamping method is the attraction imparted by the meniscus force.

在平坦化薄基板时，难以去除翘曲或起伏，因为这种基板通过常规的夹紧方法被强制变形。为了夹紧没有变形的薄基板，我们开发了一种冻结销卡盘系统，该系统通过将固定液冻结在许多销上来固定薄基板。本文介绍了这种新开发的夹紧过程的精度和固定特性。该过程包括对卡盘的温度控制，在所有销钉上形成同时高度均一的液滴的喷涂方法，以及使用熔化和再冷冻步骤以不对晶片施加冲击的放置和固定方法。剪切方向的固定强度达到110 kPa以上，对于直径为300毫米，厚度为1.2毫米，翘曲为100微米的晶圆，使用建议的夹紧工艺的最大变形仅为10微米。另外，从理论上表明，这种夹紧方法中轻微变形的原因是弯液面力所产生的吸引力。