This application is a division of, and claims priority to, United States Non-Provisional patent application Ser. No. 10/461,889, filed Jun. 13, 2003, and titled, “SINGLE WAFER METHOD AND APPARATUS FOR DRYING SEMICONDUCTOR SUBSTRATES USING AN INERT GAS AIR-KNIFE,” (Attorney Docket No. 7348) which claims priority to U.S. Provisional Patent Application Ser. No. 60/388,277, filed Jun. 13, 2002, and titled, “SINGLE WAFER METHOD AND APPARATUS FOR DRYING SEMICONDUCTOR SUBSTRATES USING AN INERT GAS AIR-KNIFE.” (Attorney Docket No. 7348/L) Both of these patent applications are incorporated by reference herein in their entirety for all purposes.
This invention is concerned with semiconductor manufacturing and is more particularly concerned with techniques for drying a substrate.
It is known to process a semiconductor substrate to achieve a dry and low-contamination condition after processing steps such as chemical mechanical polishing (CMP) and scrubbing. It has also been proposed to employ immersion drying to semiconductor substrates using the so-called Marangoni effect. An example of a Marangoni dryer is disclosed in co-pending, commonly-owned U.S. provisional patent application Ser. No. 60/335,335, filed Nov. 2, 2001 (Attorney Docket No. 5877/L), entitled “Single Wafer Immersion Dryer and Drying Methods”, and which is hereby incorporated herein by reference in its entirety.
In Marangoni drying, a substrate is raised in a vertical orientation from a fluid bath, and an alcohol vapor is delivered to a meniscus that is formed at the substrate/fluid interface. The alcohol vapor reduces the surface tension at the meniscus, thereby creating a “Marangoni” force resulting in a downward liquid flow opposite to the substrate lift direction. As a result, the substrate surface above the meniscus is dried.
Marangoni drying is promising in terms of substrate throughput, absence of water marks, and low contamination levels achieved. However, it would be desirable to achieve comparable results without the inconveniences of delivering and exhausting hazardous alcohol vapor.
According to an aspect of the invention, a method of drying a substrate is provided. The inventive method includes raising the substrate out of a fluid bath. During the raising step, an air-knife is applied to a meniscus formed at an interface between the substrate and the surface of the bath.
As referred to herein, an air-knife is not limited to using atmospheric air, but rather may use any suitable gas, including, for example, an inert gas such as nitrogen or argon.
In another aspect of the invention, a method of drying a substrate includes (1) setting a gas delivery angle for an air knife used during an immersion-drying process; (2) using the air knife during immersion drying of a hydrophilic substrate; and (3) using the air knife during immersion drying of a hydrophobic substrate. The gas delivery angle is unchanged during immersion drying of both the hydrophilic substrate and hydrophobic substrate.
