US Patent 7160808 Chuck for supporting wafers with a fluid

A method of relieving surface stress on a thin wafer by removing a small portion of the wafer substrate, the substrate being removed by applying a warm solution of KOH to the backside of the wafer while the wafer spins. The wafer may be supported on a rotatable platform adapted to direct the flow of chilled, deionized water underneath the device side of the wafer. The chilled water supports the wafer and protects the devices built-up on the wafer from the corrosive effects of KOH and from thermal damage.