Special receptacle or package – Holder for a removable electrical component – For a semiconductor wafer
Reexamination Certificate
2000-07-21
2001-09-11
Bui, Luan K. (Department: 3728)
Special receptacle or package
Holder for a removable electrical component
For a semiconductor wafer
C206S303000, C206S454000, C206S523000
Reexamination Certificate
active
06286684
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for protecting sensitive articles, such as integrated circuits, from electrostatic discharge and from mechanical shock.
BACKGROUND OF THE INVENTION
Integrated circuits (IC) are sensitive to damage due to mechanical shock. When integrated circuits are manufactured, they are contained on a substrate wafer, such as a silicon wafer. A single wafer may contain several dozen integrated circuits.
These wafers are often transported from one location to another, either in the same manufacturing facility or even from one manufacturing facility to another. The wafers that are to be transported are put into a container. Such a container is shown and described in U.S. Pat. No. 5,724,748. The wafers are stacked upon each other in horizontal fashion.
The wafers are brittle and easily damaged. If a container full of wafers is dropped or jarred, the wafers inside may break due to the mechanical shock. Thus, the container should contain some protection from mechanical shock.
In addition to mechanical shock, integrated circuits are sensitive to damage by electrostatic discharges (ESD) and electrical overstress (EOS). The circuits in integrated circuits are so small that they are easily susceptible to damage due to small charges that may accumulate.
In a wafer container, individual wafers are separated from adjacent wafers by leaf separators. Ideally, the leaf separators should protect the integrated circuits from damage due to electrostatic discharge. If a static charge on an integrated circuit is allowed to build up to a high level, then the charge is more likely to find a path to ground. This discharge results in a high instaneous flow of electrical energy, which flow is likely to overwhelm and damage the integrated circuit. In the prior art, the containers are made with walls impregnated with carbon. This allows electrical charges inside of the container to dissipate through the container walls. Unfortunately, the carbon in the walls sheds and can contaminate the integrated circuits inside of the container.
Thus, what is needed is a system to allow electrical charges on integrated circuit wafers inside of a container to dissipate harmlessly, without contaminating the integrated circuits.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a system for protecting integrated circuit wafers located inside of a container from mechanical shock.
It is another object of the present invention to provide a system for protecting integrated circuit wafers located inside of a container from electrostatic discharge and from electrical overstress.
There is provided a system for protecting integrated circuit wafers during storage and shipment. The system comprises a container having an interior space for receiving the wafers. There are first and second cushions positioned inside of the interior space so as to receive the wafers therebetween. Each of the first and second cushions has a compressible, resilient foam, with the foam being enclosed within a membrane. The membrane has one or more openings so as to allow gas to pass therethrough.
In accordance with one aspect of the invention the membrane of each of the first and second cushions comprises a film for protecting the wafers from electrostatic discharge. The film comprises a first layer made of a polymer with dissipative material therein and a second layer coupled to the first layer. The second layer is made of a polymer without the dissipative material.
In accordance with another aspect of the invention the wafers are in a stack configuration, with each of the wafers in the stack being separated from adjacent wafers by a separator. Each of the separators comprises a first layer made of a polymer with dissipative material therein and a second layer coupled to the first layer. The second layer is made of a polymer without the dissipative material.
In accordance with another aspect of the invention the wafers are in a stack configuration, with each of the wafers in the stack being separated from adjacent wafers by a separator. Each of the separators comprises a first film. The membrane of each of the first and second cushions comprises a second film for protecting the wafers from electrostatic discharge. The first and second films each comprise a first layer made of a polymer with dissipative material therein and a second layer coupled to the first layer. The second layer is made of a polymer without the dissipative material.
In accordance with another aspect of the invention, there is also a grounding conductor in contact with a portion of the second film and extending to an exterior of the container.
In accordance with another aspect of the invention, there are side cushions located around a periphery of the wafers. The side cushions comprise resilient projections extending from a base piece.
In accordance with another aspect of the invention, the first and second cushions each comprise flanges. The side cushions are interposed between the flanges.
In accordance with another aspect of the invention, each of the first and second cushions comprises a first membrane piece and a second membrane piece. The first and second membrane pieces each have edges and are coupled together along the edges so as to form an enclosure that receives the foam.
There is also provided a film for protecting articles from electrostatic discharge. The film comprises a first layer made of a polymer with dissipative material therein and a second layer coupled to the first layer. The second layer is made of a polymer without the dissipative material.
In accordance with another aspect of the invention, the first layer has a surface resistance of between 1×10
4-
1×10
11
ohms.
In accordance with another aspect of the invention, the dissipative material comprises carbon.
In accordance with another aspect of the invention, the polymer for the first and second layers comprises polyethylene and the dissipative material comprises carbon.
In accordance with another aspect of the invention, the second layer has a thickness that is less than 0.25 mils.
There is also provided a system for providing protection from electrostatic discharge. The system comprises a wafer comprising an integrated circuit, with the wafer having a circuit side. A film has a dissipative layer and an insulating layer. The film being in contact with the circuit side of the wafer such that the insulating layer is interposed between the dissipative layer and the wafer. There is also a container having an interior, with the wafer and the film being located in the container interior. The container has a conductive path from the container interior to an exterior of the container.
In accordance with another aspect of the invention, the dissipative layer of the film has a surface resistance of between 1×10
4-
1×10
11
ohms.
There is also provided a method for protecting an integrated circuit wafer from electrostatic discharge, with the wafer having a circuit side. The method comprises providing a film having a dissipative layer and an insulating layer. The film is located in contact with the circuit side of the wafer such that the insulating layer is interposed between the dissipative layer and the wafer. The wafer and the film are positioned inside of a container. A static charge is passed from the wafer to the dissipative layer through the insulating layer and out of the container to an exterior of the container.
There is also provided an enclosure for protecting articles from electromagnetic interference and radio frequency interference. The enclosure is made from a film that comprises first, second and third layers coupled together with the second layer being interposed between the first and third layers. The first, second and third layers are made of a polymer. The first and third layers are insulating. The second layer has a surface resistivity of
1
ohms or less.
Another enclosure for protecting sensitive articles from electrostatic discharge comprises a wall surrounding an interior, the in
Brooks Ray G.
Brooks Timothy
Fowler Steve L.
Neal Robert A.
Brooks Ray G.
Bui Luan K.
Mantooth Geoffrey A.
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