Patent Application
20060032784
1. Field of the Invention
The present invention relates to a foam laminate system for use in semiconductor wafer portion, particularly from the front-end to an assembly location.
2. Description of the Prior Art
The transportation of semiconductor wafers, particularly transportation from the front-end to an assembly location, which typically may involve a trans-oceanic voyage, presents a set of challenges. Mechanical and electrostatic protection must be provided. Contamination levels must be kept low to prevent the introduction of ions that, in combination with moisture vapor, generate corrosion, pitting and/or transistor inversion. Extreme cleanliness required during the shipping of the semiconductor wafers. Similarly, mechanical protection of the semiconductor wafers during transportation can be problematic if the wafer container is not completely full.
It is therefore an object of the present invention to provide a cushion-like element for the transportation of semiconductor wafers which maintains the low contamination levels required for such transportation.
It is therefore a further object of the present invention to provide a cushion-like element which provides mechanical and electrostatic protection to semiconductor wafers during transportation.
These and other objects are attained by providing a cushion with a cylindrical interior formed of closed cell polyethylene foam, typically one quarter to three eighths of an inch thick, with a diameter approximately equal to the diameter of the semiconductor wafers to be transported. A thin outer surface of electrostatic discharge (ESD) dissipative polyethylene is laminated to the polyethylene foam interior by hot melt EVA adhesive. The exterior surface is perforated with small apertures, typically less than 0.010 inches in diameter, to allow for compression upon impact. The ESD dissipative polyethylene is heat wire cut to seal the ends about the periphery of the cushion.
Further objects and advantages will become apparent from the following description and from the accompanying drawing, wherein:
Referring now to the drawings in detail wherein like numerals indicate like elements throughout the several views, one sees that
The cushion-like device 10 is designed to generate contamination levels below 50 ppm (leachable alkanes, anions, halogens, ammonias or cations) as detected through leach testing at 60°0 and 90° Centigrade testing at one hour soak durations, as well as organic and inorganic analysis. The low organic/inorganic and acid compound material contamination reduces ion contamination, pitting and corrosion on tight geometry 90 nanometer (and below) semiconductor wafers during shipping.
In order to use cushion-like device 10, the user typically places separations (not shown) between successive semiconductor wafers (not shown). A separator which is particularly well adapted for this application is disclosed in U.S. provisional application Ser. No. ______, filed on Jul. 13, 2004, entitled “Scribed Interleaf Separator Wafer Packaging”. The cushion-like device 10 is placed at one or both ends of the stack of semiconductor wafers and separators and the resulting stack is placed into a container adapted for semiconductor wafer transportation. A container which is partially well adapted for this application is disclosed in PCT/US04/14659, filed on May 10, 2004, entitled “Wafer Box with Radially Pivoting Latch Elements”. The appropriate number and thickness of cushion-like devices 10 are chosen so that the semiconductor wafers are mechanically constrained within the container.
Thus the several aforementioned objects and advantages are most effectively attained. Although a single preferred embodiment of the invention has been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.
