Surface Phenomena: Rinsing and Drying
Rinsing and drying processes are critical to control after the cleaning and etching steps. Rinsing and drying should not adversely affect the cleaned wafer surface. The rinse must completely wet the wafer, and then be efficiently removed from both planar surfaces and features. The chemicals and the cleaning byproducts must be removed leaving no residual layer of water on the surface. Watermarks must be prevented from forming on hydrophobic surfaces by controlling the drying process and minimizing the amount of dissolved silica in the water. Additionally, contaminants must not redeposit on the wafer surface during these processes. This chapter reviews the physics and chemistry of rinsing and drying by discussing Young’s wetting equation, surface tension and energy, stiction, and electrostatic charging.
Keywords: rinsing, drying, surface charge, surface energy, surface tension, watermarks, water droplet, silica solubility, silicic acid, quick dump rinser, overflow rinser, cascade rinser, spin rinse dryer, Marangoni dryer, stiction
4.1 The Surface Phenomena of Rinsing and Drying
The ability to rinse and dry a surface after being exposed to cleaning and etching chemical is critical for the surface conditioning ...