Refrigeration – Processes – Treating an article
Reexamination Certificate
1999-12-30
2001-03-20
Tapolcai, William E. (Department: 3744)
Refrigeration
Processes
Treating an article
C062S064000, C062S259200, C062S373000
Reexamination Certificate
active
06202423
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to device transportation systems, and in one embodiment, to a method and system for forming ice on spherical-shaped objects for use in the manufacture and transport of spherical-shaped semiconductor integrated circuits.
Conventional integrated circuits, or “chips,” are formed from a flat surface semiconductor wafer. The semiconductor wafer is first manufactured in a semiconductor material manufacturing facility and is then provided to a fabrication facility. At the latter facility, several layers are processed onto the semiconductor wafer surface. Once completed, the wafer is then cut into one or more chips and assembled into packages. Although the processed chip includes several layers fabricated thereon, the chip still remains relatively flat.
A fabrication facility is relatively expensive due to the enormous effort and expense required for creating flat silicon wafers and chips. For example, manufacturing the wafers requires several high-precision steps including creating rod-form polycrystalline semiconductor material; precisely cutting ingots from the semiconductor rods; cleaning and drying the cut ingots; manufacturing a large single crystal from the ingots by melting them in a quartz crucible; grinding, etching, and cleaning the surface of the crystal; cutting, lapping and polishing wafers from the crystal; and heat processing the wafers. Moreover, the wafers produced by the above processes typically have many defects which are largely attributable to the difficulty in making a single, highly pure crystal due to the above cutting, grinding and cleaning processes as well as due to the impurities, including oxygen, associated with containers used in forming the crystals. These defects become more and more prevalent as the integrated circuits formed on these wafers become smaller.
Another major problem associated with modern fabrication facilities for flat chips is that they require extensive and expensive equipment. For example, dust-free clean rooms and temperature-controlled manufacturing and storage areas are necessary to prevent the wafers and chips from defecting and warping. Also, these types of fabrication facilities suffer from a relatively inefficient throughput as well as an inefficient use of the silicon. For example, because the wafers are round and the completed chips are rectangular, the peripheral portion of each wafer cannot be used.
Therefore, due to these and various other problems, only a few companies in the world today can successfully manufacture conventional flat chips. Furthermore, the chips must bear a high price to cover the costs of manufacturing, as well as the return on initial capital and investment.
In U.S. Pat. No. 5,955,776, assigned to the same assignee as the present application and hereby incorporated by reference as if reproduced in its entirety, a method and system for manufacturing spherical-shaped semiconductor integrated circuits is disclosed. A manufacturing process disclosed in the aforementioned patent utilizes “tubes” to not only process the spherical-shaped semiconductor integrated circuits, but to transport them from process to process. By using tubes in this manner, a true pipeline production system is obtained, and conventional clean room requirements are significantly reduced.
Complicating the manufacturing process for spherical-shaped semiconductor integrated circuits are the special handling requirements which must be afforded the circuits during their manufacture. Unlike conventional integrated circuits formed on only one surface of a semiconductor wafer, the spherical-shaped semiconductor integrated circuit produced from a spherical-shaped substrate may consume the entire surface area of the substrate. Therefore, the spherical-shaped semiconductor integrated circuits cannot be placed on a conventional wafer chuck or carried in a conventional wafer boat. If this were done, at least a portion of the substrate's surface, and any integrated circuit produced thereon, would receive harmful physical contact. Furthermore, even tube processing and transporting, such as is disclosed in presently incorporated U.S. Pat. No. 5,955,776, may cause harmful physical contact. It is understood that although a moderate amount of contact may not be harmful, contact caused by bumping around a processing or transport tube can cause severe damage to the spherical-shaped semiconductor integrated circuits.
Thus, there remains a need for a system and method capable of readily transporting spherical-shaped objects without causing harmful physical contact.
SUMMARY OF THE INVENTION
The present invention provides a method and system for transporting objects without causing harmful physical contact. The method and system can be used, for example, in a manufacturing process for fabricating spherical shaped semiconductor devices. In one embodiment, the method cools the spherical shaped device and applies moisture such as de-ionized water. The moisture forms a coat of ice on an outer surface of the cooled spherical shaped device. The spherical shaped device with the coat of ice can then be easily transported, the ice preventing any harmful physical contact to the device. Once the spherical shaped device with the coat of ice has been transported, the device is heated to remove the coat of ice therefrom.
In some embodiments, one or more of the steps are performed in tubes. In fact, a continuous tube can be used for a significant portion of the entire manufacturing process.
Referring now to the system, in one embodiment the system includes a cooler for cooling the spherical shaped device and a moisture applicator for providing moisture to an outer surface of the cooled spherical shaped device. The moisture can thereby adhere to the spherical shaped device to form a coat of ice thereon. The system also includes transporting means, such as a tube, for transporting the spherical shaped device with the coat of ice on the outer surface. The system may also include a heater for heating the semiconductor device with the coat of ice after it has been transported. The heating serves to convert the coat of ice to a moisture gas. In some embodiments, the system includes a condensing system for drawing the moisture gas from the semiconductor device.
In some embodiments, the cooler is a fluid, such as nitrogen. The nitrogen fluid may also facilitate movement of the semiconductor device.
REFERENCES:
patent: 2819594 (1958-01-01), Lorie
patent: 2876109 (1959-03-01), Hemery et al.
patent: 2879005 (1959-03-01), Jarvis
patent: 3458324 (1969-07-01), Kramer
patent: 4548045 (1985-10-01), Altares et al.
patent: 4869090 (1989-09-01), Tada et al.
patent: 5216890 (1993-06-01), Ban et al.
patent: 5955776 (1999-09-01), Ishikawa
Bell Semiconductor, Inc.
Haynes and Boone LLP
Tapolcai William E.
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