Material or article handling – Movable rack having superposed – charge-supporting elements,... – Rotating or circulating rack
Reexamination Certificate
2001-07-10
2004-02-03
Keenan, James W. (Department: 3652)
Material or article handling
Movable rack having superposed, charge-supporting elements,...
Rotating or circulating rack
C414S331110, C414S331140, C414S940000
Reexamination Certificate
active
06685419
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to industrial-mechanical devices that assists in the production of semiconductors and improve the safety and efficiency of the semiconductor manufacturing environment.
BACKGROUND OF THE INVENTION
Currently, there are a variety of tools available to assist the semiconductor processing personnel in handling of semiconductor wafer boats. However, much of the risk in the semiconductor-manufacturing environment still includes poor ergonomic practices, which subject the handlers to personal risk and the very expensive product to contamination risks. One of the most inefficient and risk prone dangerous areas are the horizontal furnaces used to process the silicon wafers.
There are small tools for safe handling and transporting of silicon wafers, which include vacuum wands, manual wands (wafer tweezers), vacuum pumps (spurious), tubing, and tweezers for various size wafer handling, etc. Mactronix, Amtech, TEL Tokyo Electron Ltd, Fluoro Mechanic of Tokyo, Japan, and Tystar of Torrance, Calif. are examples of companies that manufacturer these advanced wafer handling tools for the semiconductor industry.
However, currently there is very little automation of the horizontal furnace process in use despite the fact that there have been great advances in the automation of wafer handling up to and around the furnaces. The actual critical steps of loading and unloading wafers boats from horizontal furnaces despite two decade's worth of attempts to improve productivity around the loading and unloading of furnaces, still resist the applications of automation.
This lack of automation tools around the horizontal quad stack furnace is surprising, since operators in the fabrication areas are challenged to perform awkward, inefficient, and hazardous manual tasks when in physical possession of expensive wafer loads.
Examples of overall automated material processing systems for the semiconductor manufacturing environment are contained within U.S. Pat. Nos. 6,157,886 and 6,045,235, and 5,838,566 developed by Conboy, et. al. and owned by Advanced Micro Systems of Sunnyvale, Calif. It is unclear whether such systems are commercially viable on a mass scale because of the expense of retooling of the fabrication area to employ such a customized comprehensive fabrication system. Additionally, these computer-controlled comprehensive method(s) for managing material fabrication are not really relevant to the actual physical processes involved in the fabrication area, but more to a general method of manufacturing control and optimization. Another example of complex automated material handling units is taught by U.S. Pat. No. 4,829,445, which is illustrated by FIG.
2
and invented by Burney and owned by National Semiconductor Corporation of Santa Clara, Calif. However, this invention is directed at a particular device/system for material processing but like the above patent, requires extensive installation and computer controls and expense.
In general, the complex automated solutions are too expensive. They are slow (reducing throughput), with an ever-present risk of cross-contamination, difficult to install and maintain, with a maneuverable space requirement, which is much greater in practice than claimed by some suppliers. Such systems require high cost in time, space, and expense, in most instances actually reduce the throughput of the furnace, hampering productivity. Claims made by entities investing in full furnace automation on the grounds that it prevents “miss processing” by the operator are often largely exaggerated. Hence, the semiconductor industry has found it more effective to continue to employ operators despite the continued risks to both operator and product.
FIG. 1
represents a typical quad stack horizontal furnace
10
for processing semiconductor wafers. The furnace consists of four furnace tubes, with cantilevered loaders
12
,
14
,
16
,
18
on which wafer boats containing typically 50 wafers must be carefully placed. Furnace
12
and
14
will exist at a height of 80 and 60 inches or greater respectively above the floor level. When cantilever-loading systems became popular in the 1980's it was expected that automation of the loading and unloading of such semiconductor processing devices would quickly follow. Despite some very ambitious attempts by furnace manufacturers and other companies to automate the process, the numbers of fabricating environments employing automated furnace loading are a tiny minority. Horizontal furnace automation has been unsuccessful for several reasons, mainly capital expenditure, high maintenance costs, reduced throughput, and difficulty of installation among others.
Because automation attempts have failed due to the above-mentioned expense and convenience issues, the semiconductor wafer boats are still handled manually around the furnace. The first difficult set of actions performed by a typical operator is the action of unloading the top tube of the quad stack horizontal furnace at level
12
, which is typically approximately 80″ above floor level. Typically, operators climb up and down (backwards) a set of 2 or 3 steps with some hand held fork lift device to remove a single wafer boat from the cantilever. The loading process is the reverse, climb up with load in one hand, load and climb down empty handed, backwards. In all a total of 24 trips are needed to load and unload (6×2=12 boats=600 wafers) the wafer boats from a typical single tube process.
What is needed is a simple solution to bridge the gap between the expense and complexity of full automation and reducing the responsibility and risks to operators that is affordable and does not require extensive retooling of the fabrication area.
SUMMARY OF THE INVENTION
The present invention addresses many of the above discussed needs by facilitating sensible, safer and ergonomically efficient loading, unloading, and transporting of silicon wafers in the manufacturing environment, all at a relatively small cost to the semiconductor manufacturer. The present invention represents an effective low cost contribution to the improved productivity of horizontal furnace processing.
It is the object of the present invention, the Elevator/Transporter (also referred to as the “E/T”™), to uniquely combine a means by which batches of semiconductor wafers, can be transported back and forth between any of the furnaces (left hand or right hand configuration) and any of the “transfer stations” in the fabrication area, elevated to any required cantilever level and back down to the correct height for easy loading/unloading at the transfer station, store and queue the wafers in one self contained apparatus. The present invention is simple, affordable, requires the use of little space in the semiconductor fabrication area, and that which it does require, since it is mobile, is a non issue as it can be simply rolled out of the way as necessary to provide space.
Using the present invention, wafers are staged by the operator from the transfer station prior to hot processing and loaded into a rotating drum feature on the invention. The device is wheeled or rotated about its axis, depending on the configuration of the fabrication area, over to the furnace where the operator presses the button to raise the drum to the required, pre-set, load level. In a typical operation, using the optional steps, the operator climbs to tube level, with both hands free for safety. The operator is now able to unload the cantilever of the processed wafers and place them into the invention.
The operator rotates the drum bringing up the next batch for the furnace and while still in position loads the cantilever and starts the next run. The operator can then climb down the steps with both hands now free and wheel the invention with processed wafers safely enclosed, to the next workstation.
The resulting benefits of using the present invention are described in the bullet points below but briefly stated the present invention provides safer, quicker, more reliable furnace loa
Keenan James W.
Perkins Coie LLP
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