(610e) Wave-Front Propagation of Rinsing Flows on Rotating Semiconductor Wafers

During the manufacture of silicon circuits it is important that the surface of the wafer is extremely clean. It has been found that procedures for rinsing contaminants such as particles from the surface can be more effective when the wafer is rotating rapidly. However, when a jet of liquid is applied to a rapidly rotating surface, centrifugal forces can pull spiral-like ribbons of fluid out from the radially advancing wave-front. This is problematic because the rinsing flow is uneven and particles or other contaminants can build up along the edges of these ribbons of fluid resulting in higher instances of product failure at these locations.

A better fundamental understanding of the flow in these systems is essential for reducing yield losses while taking advantage of the benefits of rotation during rinsing. This is especially important as the size of features on the surface of the wafers decreases and therefore the requirements for cleanliness continue to become more strict. In the present work, the impact of the jet flow-rate and wafer rotation-speed on the propagation of the wave-front on a clean, dry wafer is investigated. These results are then compared to the propagation of the wave-front on a wafer that has been “pretreated” with a thin layer of various fluids with different bulk and interfacial properties. It is shown that the properties of the pretreatment fluid can influence both the dynamics of the wave-front propagation as well as the formation of the spiral-like ribbons of fluid.