Method of treating a substrate

Abstract

A method of cleaning a substrate within a controlled environment includes placing the substrate into a high pressure vessel. The high pressure vessel is then supplied with a dense fluid under pressure. The dense fluid is contacted with the substrate for a selected period of time to at least partially remove a contaminant contained on the substrate. After the selected period of time, the vessel is depressurized to at least partially convert the dense fluid into a vapor. The vapor is then subjected to an energy field to form a plasma within the vessel which is used to treat the substrate for a second selected period of time. The thus cleaned substrate is then removed from the vessel.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) [0001] This application is a divisional application of U.S. patent application Ser. No. 10 / 428,793 entitled METHOD AND APPARATUS FOR SELECTIVE TREATMENT OF A PRECISION SUBSTRATE SURFACE, filed on 2 May 2003, which claimed the benefit of similarly named U.S. Provisional Application No. 60 / 377,197 filed on 3 May 2002, each of which are hereby incorporated herein by reference.BACKGROUND OF INVENTION [0002] As technology has advanced, the system performance requirements and complexity of manufactured and assembled precision instruments and devices have increased, while the size of individual components and assemblies have decreased. This continuing miniaturization process has magnified the susceptibility of precision substrates and surfaces to contamination. Specific effects of contamination depend on the type of substrate, materials used, and system in which the device is used. [0003] Thus, an important element of any precision manufacturing or...

AI Technical Summary

Benefits of technology

[0022] As line size becomes smaller and the complexity of precision manufactured devices increases, it is clearly desirable to have an all dry cleaning and surface treatment technique, including both method and apparatus, that selectively removes unwanted organic films ad particles, prevents additional particles, and does not introduce compatibility problems for the manufactured device. The complete selective cleaning technique may also include a step of drying the precision substrate, without other adverse results. A further desirable characteristic includes reducing or possibly eliminating re-contamination of precision surfaces during cleaning and handling. The aforementioned conventional technique fails to provide such desired features, thereby reducing the yield of good precision devices.

[0057] Moreover, medical substrates such as boroscopes, polyester grafts, polyurethane blood filters may be treated using the present invention to remove residues, particles, biological contaminant and may be treated using plasma techniques to improve wetability and biocompatibility. Still moreover, the plasma-dense fluid cleaning-modification combination may be used to clean and treat commercial textiles and fabrics to remove complex surface soils and to brighten fabric fiber surfaces, respectively.

Problems solved by technology

Although very attractive, these individual techniques have discrete characteristics, that is application and performance limitations, which prevent them individually from properly treating a substrate surface and may even damage a surface.

For example, physical damage to a substrate surface may be caused by a particular technique due to excessive cleaning energies required (i.e., high spray pressure, high plasma energy level, presence of oxidizing chemistries) and excessive treatment periods required to achieve a certain surface cleanliness level.

Most conventional wet and dry combinations create significant waste by-products, pose worker exposure dangers, and consume tremendous amounts of water resources.

However, complete drying of precision substrates following cleaning by wet methods is limited due to hydration of small capillaries, vias and interstices that may be present.

Moreover, a lack of substrate surface selectivity can be limiting in many applications, because the entire precision device is subjected to the combinational cleaning method that complicates cleaning, drying and compatibility issues.

This superheated or saturated drying vapor often requires the use of large quantities of a hot volatile organic material.

A limitation with this type of drying technique is its use of the large solvent quantity, which is hot, highly flammable, and extremely hazardous to health and the environment.

Another limitation with such a drying technique is its cost, which is often quite expensive.

The aforementioned conventional technique fails to provide such desired features, thereby reducing the yield of good precision devices.

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