Ventilation – Clean room
Reexamination Certificate
2001-10-25
2004-11-16
Boles, Derek S. (Department: 3749)
Ventilation
Clean room
C055S385200
Reexamination Certificate
active
06817941
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to the field of air handling and particularly to airflow diffusers.
BACKGROUND OF THE INVENTION
Electronics have become an increasingly, competitive industry as technology becomes more pervasive in society. The inclusion of electronic components in a variety of devices increases the demand for components. With the current demand for electronic devices, production techniques become more important as competitors seek to gain an advantage over their competition. As a result, innovations in the field of electronics production may yield a tremendous advantage in reputation and increased savings due to reduction in the number of rejected products.
Critical to the production of electronic devices is quality control. The number of products failing to meet desired standards can severely impact the production costs. As a result, emphasis is placed on increasing the quality of the electrical components and reducing the number of non-conforming products.
An important area of quality control in electronics manufacturing is the elimination of contamination on wafers during microprocessor chip manufacturing. During chip production substrate wafers may be subject to having particles deposited on the wafer surface. Particle deposition in critical wafer areas may make it unusable. Thus, the elimination of contaminate particles may result in higher quality and thus a reduction in non-conforming microchips.
During microchip production, typically manufacturing is conducted utilizing chambers to control process conditions. Airflow through the chamber may aid in removing particles generated as wafer production is conducted. Process chambers rely on air filters such as an ultra low penetrating air (ULPA) filters to eliminate contaminates from air entering the chamber, and to remove contaminates generated during manufacturing. One difficulty with current air-handling systems is that once the air is passed through the air filter the flow of air is often disrupted downstream of the air filter resulting in uneven airflow and even possible turbulent conditions. Uneven airflow may result in particles being entrained in turbulent air currents, rather then exiting the chamber as desired. Entrained particles may be reintroduced to the air-stream if should an event disturb the airflow. The airflow may be disturbed for example, by robotic mechanisms producing the semiconductors and the like. Entrained particles may contaminate then contaminate the wafer.
Another drawback to current airflow systems is that the air filters often are not designed to fit the entire airflow entrance plane of the chamber. Thus air may be directed from only a portion of a side of the chamber, such as from the center of the top of the chamber. As a result of limited air dispersion, air may not be directed through-out the entire chamber resulting in zones where particles may be trapped.
Additional problems include, the cost and complexity of retrofitting chambers having unacceptable airflow system, with larger and irregularly shaped filters. Furthermore, the lack of suitable airflow system addressing the above mentioned difficulties will result in the continuation of defects in products and low manufacturing efficiency.
Therefore, it would be desirable to provide a airflow diffuser suitable for providing uniform airflow.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an air diffuser for utilization in a process chamber, such as a chamber utilized in manufacturing microprocessor chips. In a first aspect of the present invention, a process chamber airflow system includes an air diffuser suitable for providing uniform airflow through the chamber. Initially, a blower may generate an initial flow of air. The initial flow of air may be directed through an air filter disposed in the connection between the blower and a plenum.
Connected to the plenum and disposed in the airflow may be an air diffuser containing a plurality of holes. The plurality of holes in the air diffuser may reduce the flow of air through the holes when compared to the initial flow of air generated by the blower. The plurality of holes in the air diffuser may contain a cross-sectional area, through which air may flow through, less then that of the initial inlet, unrestricted air entrance plane, cross-sectional area generated by the blower.
The reduction in the cross-sectional area may result in a back flow of air in the plenum and a resultant rise in pressure. The rise in pressure may generate a uniform dispersal in airflow across a side of the air diffuser disposed against the plenum. The rise in pressure may yield a uniform flow of air through the plurality of holes and substantially laminar airflow.
In a second aspect of the present invention, an air diffuser suitable for utilization in a process chamber is disclosed. The air diffuser includes a plate with a first and a second side and a plurality of holes contained within the plate penetrating the first and second sides. The plurality of holes in the plate may be uniformly dispersed and be sufficient to cause the second side of the plate to experience a pressure lower then that of the first side when disposed in an airflow.
In a third aspect of the present invention a method of providing substantially laminar airflow in a process chamber is disclosed. Providing substantially laminar air flow includes generating an initial flow of air with an initial cross-sectional area. Disposing an air diffuser with a plurality of uniformly spaced holes with a total cross-section less than the initial airflow in the flow of air generated by the blower. An increase in a back-pressure of air may be created due to the reduction is cross-sectional area, resulting in an eventual dispersion of a portion of the initial airflow uniformly across the air diffuser. Subsequently, a uniform flow of air may be provided through the plurality of holes included in the air diffuser to the process chamber.
It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.
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Boles Derek S.
LSI Logic Corporation
Suiter - West PC LLO
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