One of the most important processes in the fabrication of integrated circuits involves the rinsing and drying of the semiconductor wafers between various chemical processing steps. During rinsing, de-ionized (DI) water is often used to assist in the removal of chemicals from the surface of the wafer. After rinsing is completed, the wafer surface must be dried. It is during the drying step that wafer contamination often results. Such contamination is due to the fact that the evaporation of the DI water deposits contaminant particles on the wafer surface.
Various techniques have been proposed for the rinsing and drying of semiconductor wafers. One technique used to both rinse and dry wafers relies upon a spin rinser/dryer. Such a system uses a DI rinse water spray to rinse the wafer. The wafer is spun during the drying step thereby removing the water from the surface of the semiconductor wafer through evaporation and the action of centrifugal acceleration.
Other techniques used to dry wafers include the use of isopropyl alcohol (IPA) vapor dryers, full displacement IPA dryers, and other forms of IPA dryers. These IPA dryers rely upon a large quantity of a solvent, such as IPA and other volatile organic liquids, to facilitate drying of the semiconductor wafer. One limitation of this type of dryer is its use of large solvent quantities which are highly flammable and often hazardous to health and environment. Further, these dryer types are often quite expensive. Still further, the large quantities of hot solvent are often incompatible with certain recessed pattern wafers and may be detrimental to certain device structures.
A still further drying technique is known as a Marangoni dryer. In a Marangoni dryer, the wafer is slowly withdrawn from the rinsing liquid in an atmosphere having a vapor that is miscible with the rinsing liquid. As the wafer is withdrawn, a meniscus is formed at the wafer surfaces. The surface tension of the rinsing fluid at the meniscus is reduced as a result of the presence of the vapor. The reduced surface tension gives rise to a substantially particle free drying process.
The demands for integrated circuit rinsing/drying processes may ultimately require more control and economic efficiency from the rinser/dryer. As such, a substantially new approach to rinsing and drying of the semiconductor wafer has been undertaken which provides greater control of the rinsing and drying fluids. Further, wafers may be rinsed and dried on an individual basis more quickly when compared to the drying of an individual wafer using any of the foregoing processes