Heating – Work feeding – agitating – discharging or conveying... – Removable furnace bottom section or kiln cart
Utility Patent
1999-10-05
2001-01-02
Ferensic, Denise L. (Department: 3749)
Heating
Work feeding, agitating, discharging or conveying...
Removable furnace bottom section or kiln cart
C432S056000, C432S239000, C118S725000, C118S728000, C414S935000, C414S937000
Utility Patent
active
06168427
ABSTRACT:
TECHNICAL FIELD
The present invention broadly relates to equipment for manufacturing semiconductor devices, such as integrated circuits, and deals more particularly with apparatus for aiding in the removal of a fragile processing tube from a semiconductor furnace.
BACKGROUND OF THE INVENTION
In connection with processes used to manufacture semiconductor devices, such as integrated circuits, numerous process steps are carried out in a controlled environment at elevated temperatures. Such processes includes oxidation, diffusion, chemical vapor deposition and annealing. In order to realize elevated processing temperatures, semiconductor wafers are processed in an evacuated chamber, typically in a form of a quartz tube which is housed within a semiconductor furnace.
The most common type of semiconductor furnace is of the so-called “hot wall” electric type which facilitates batch processing of semiconductor wafers. Furthermore, hot wall electric furnaces exhibit excellent temperature stability and precise temperature control. Modern hot wall diffusion furnaces are capable of controlling temperatures over the range of 300°-1200° C. to an accuracy of 0.5° or −0.5° C. Hot wall furnaces were initially designed as horizontal diffusion furnaces, however, more recently, vertical furnaces have gained favor because they present a number of advantages over their horizontal predecessors. These advantages include: elimination of cantilever or soft-landing since the wafers are held in a quartz boat which does not touch the process tube walls; wafers can be loaded and unloaded automatically; and, the clean room footprint of the system is somewhat smaller than that of the conventional horizontal configuration.
Vertical semiconductor furnaces of the type mentioned above employ a quartz tube which typically has a polysilicon coating when used for a deposition or annealing process. The polysilicon deposition reduces the power loss due to quartz reflection or radiation, and reduces the degradation of a boat occasioned by wet etching.
Because semiconductor furnaces are subjected to high rates of usage and their components are exposed to harsh operating environments, periodic maintenance must be performed on various furnace components, including the quartz tube assembly. In the past, in order to remove a quartz tube from the furnace for repair or maintenance, a technician would draw the tube from the bottom of the furnace. This removal process was sometimes accomplished by using a mechanical arm, but even with the aid of such mechanical devices, tube removal was tedious because of the tight clearance between the outer walls of the tube, and the inside wall of the furnace. Consequently, as the technician attempted to withdraw the tube from the furnace, the fragile tube often came in contact with the sidewall or edges of the furnace, resulting in breakage of the tube. Tube breakage results in the additional expense of replacing the tube as well as downtime of equipment. Moreover, tube breakage, especially when the tube remains hot, presents a risk of injury to the technician handling the tube removal.
Accordingly, there is a clear need in the art for tools or equipment that facilitate the removal of the quartz tube from the furnace that preclude or substantially reduce the possibility of the tube coming in contact with the sidewalls of the furnace during the removal process. The present invention is directed toward satisfying this need.
SUMMARY OF THE INVENTION
According to one aspect of the invention, apparatus is provided for aiding in the removal of a tube from a surrounding furnace, wherein the furnace includes a cylindrical body surrounding the tube and an open end at the bottom thereof through which the tube may be removed. The apparatus includes a plurality of circumferentially spaced guides, and means for mounting the guides on the base of the furnace body such that the guides are provided with radial adjustment so that they may be moved into contact with the sidewalls of the tube during withdrawal, and thereby guide the withdrawal of the tube to prevent contact with the furnace body. The guide mounting means includes a plate, means for securing the plate on the base of the furnace body, and slide means for slidably mounting the guides for radial adjustment. The guides are preferably in the form of Teflon coated wheels mounted on the inner extremities of the slides. The plate is ring-shaped and may comprise first and second portions coupled together by a tongue and groove interconnection.
It is therefore a primary object of the present invention to provide apparatus for aiding and the removal of a fragile procesing tube from a semiconductor furnace which reduces the possibility of tube breakage due to contact with the walls of the furnace.
Another object of the invention is to provide apparatus as described above which is especially simple in construction and may be retrofitted to existing furnaces.
A further object of the present invention is to provide apparatus of the type mentioned above which may be permanently mounted on the furnace, but yet which does not interfere with normal furnace operation.
A still further object of the present invention is to provide apparatus as described above which positively engages the sidewalls of the tube so as to maintain the tube coaxial with the longitudinal axis of the furnace body, but yet which does not damage the tube.
These, and further objects and advantages of the present invention will be made clear or will become apparent during the course of the following description of a preferred embodiment of the invention.
REFERENCES:
patent: 4781511 (1988-11-01), Harada et al.
patent: 5000682 (1991-03-01), Heidt et al.
patent: 5676869 (1997-10-01), Nakayama et al.
Chen Yi-Jen
Cho Guey-Shyung
Ferensic Denise L.
Taiwan Semiconductor Manufacturing Co. Ltd
Tung & Associates
Wilson Gregory A.
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