Material or article handling – Device for emptying portable receptacle – Nongravity type
Reexamination Certificate
1999-07-08
2001-06-12
Werner, Frank E. (Department: 3652)
Material or article handling
Device for emptying portable receptacle
Nongravity type
C414S217100, C414S684300, C414S937000, C414S939000, C118S719000
Reexamination Certificate
active
06244812
ABSTRACT:
TECHNICAL FIELD
The invention relates generally to systems for handling wafer supporting devices and more particularly to systems for automatically removing and reattaching a door of a device for storing an array of semiconductor wafers.
BACKGROUND ART
Wafer transfer systems are used to provide an automated transfer of semiconductor wafers from one position to another position. For example, the wafers contained in a cassette may be moved individually to a processing chamber for depositing and patterning layers of material for forming integrated circuit chips. Robotic handling devices are preferred, since human handling is more likely to cause contamination.
Conventional cassettes include slots that support the wafers in a vertical orientation. The wafers are removed from a cassette by lifting the wafers through an open top portion of the cassette. An automated transfer system that may be used to move semiconductor wafers between a cassette and a processing chamber is described in U.S. Pat. No. 4,449,885 to Hertel et al. The transfer system of Hertel et al. includes a cassette conveyor assembly for moving one or more cassettes horizontally. An elevator blade passes upwardly through the cassette to contact a lower edge of a wafer that has been moved into place by the conveyor assembly. The wafer is then raised to a position in which the elevator blade transfers the wafer to a vacuum chuck of a processing chamber. When the processing of the wafer has been completed, the wafer is returned to the cassette by the elevator blade.
Another type of wafer storage device is referred to as a Standardized Mechanical InterFace (SMIF) pod. A SMIF pod is described in U.S. Pat. No. 5,653,565 to Bonora et al. The wafers are held in a horizontal orientation, rather than a vertical orientation. The Bonora et al. patent describes a typical SMIF system as having three main components: (1) a sealed pod for storing and transporting cassettes that hold the semiconductor wafers; (2) enclosures placed over the cassette ports and wafer processing areas of processing equipment, so that the environments within the pods and the enclosures become miniature clean spaces; and (3) a transfer mechanism to load and unload wafers from the sealed pod without contamination of the wafers. In operation, when the semiconductor wafers are being transferred into the processing equipment, the pod is loaded onto an access port along an upper horizontal surface of the processing equipment. The pod door and the access port are preferably opened simultaneously, so that the exposure of the wafers to particles is minimized. An elevator lowers the pod door and the door of the access port, with the cassette riding on the pod door into the processing chamber. Thus, the wafers are removed from the pod in a protected manner.
Another type of wafer container is described in U.S. Pat. No. 5,711,427 to Nyseth. The Nyseth wafer container is described for use with 300 mm diameter semiconductor wafers. The container is sometimes referred to in the industry as a Front Opening Unified Pod (FOUP), since the wafers are stored in a horizontal orientation and the access door to the pod is located on a side that is perpendicular to the horizontally stored wafers. Automated transfer systems for use with FOUPs have been designed. The transfer systems are significantly different than the systems used with other types of containers, since the door is vertically mounted and the wafers are horizontally stored.
Typically, the access door of the FOUP includes a latching mechanism to ensure that the door remains in place until removal or insertion of wafers into the pod is desired. Devices for automatically removing the access door are known. Such devices typically rest on the floor adjacent to the equipment on which the FOUP is rested. A mechanism rises along guide rails to the access door and unlatches the door. The mechanism is then lowered to a rest position. One concern with such a device is that it requires stand-alone automated equipment to accommodate the movement of the door-removal mechanism. This may be undesirable in some applications. Another concern is that the extended movement of the door-removal mechanism may promote the generation of particles, since motors or other drive devices must be used in the operation of the mechanism. This is undesirable in an environment in which semiconductor wafers are to be exposed.
What is needed is a system for manipulating an access door of a wafer-supporting device such that system real estate requirements and the risk of generating particles are low.
SUMMARY OF THE INVENTION
An automated door removal and replacement system may have a small profile and a small horizontal space requirement by utilizing a combination of linear and rotational drive to contact a door, remove the door, and then store the door below a wafer-supporting device from which the door was removed. In the preferred embodiment, the system is used with a wafer-supporting device having horizontally oriented wafers and a vertical door. A door-contacting assembly is pivotally mounted to include a horizontal rest position and a vertical unlocking position. In applications in which the wafer-supporting device includes a latching mechanism, the door-contacting assembly includes keys aligned and configured to latch and unlatch the door.
In one application, unlocking a door of a wafer-supporting device includes a rotational motion followed by a linear motion. The door-contacting assembly swings from below the wafer-supporting device to the upright position. The assembly then moves horizontally to contact the door of the device. Where applicable, the horizontal movement inserts the latching/unlatching keys into the appropriate locations on the door. Often, the keys must be manipulated to release the door from the wafer-handling device, but this depends upon the type of device. For example, removal of the door of a FOUP requires that the keys be rotated approximately 90°. This rotation may be achieved by activating one or more electrically activated members, such as solenoids within the door-contacting assembly.
After the door has been properly engaged by the door-contacting assembly, the assembly is moved linearly away from the wafer-supporting device. This provides proper clearance for rotating the assembly to the lowered position in which the door resides below the wafer-supporting device. In this position, the door is generally horizontal. Thus, the storage space is less than would be required if the door were to be stored vertically.
Following the insertion or removal of wafers from the device, he door can be replaced by following the same steps, but in reverse order. hat is, the door-contacting assembly and the door are rotated to an upright condition in alignment with the front opening of the wafer-supporting device. The assembly is moved linearly to position the door within the opening of the device. The door is again latched and released from the door-contacting assembly. The assembly is returned to its rest position, allowing the device to be removed from the system.
An advantage of the invention is that the rotation of the door-contacting assembly conserves real estate. Much of the structure for automatically removing and replacing the door can be immediately below the wafer-supporting device. Thus, horizontal real estate requirements are relatively low. Moreover, by pivoting the door to a horizontal position, the system may have a relatively low profile, i.e., the vertical real estate requirements are low. There is no extended movement of the door-contacting assembly comparable to the movement along vertical guide rails of the type utilized in some prior art systems for removing doors from wafer-supporting devices.
While the system is designed primarily for front opening devices, such as FOUPs, there are advantages to using the system for automatically removing and returning doors of top-opening devices. For example, rather than a 90° pivot of the door-opening assembly from the horizontal rest position to the vertical contact position
Dill Charles Thomas
Patterson Jesse
H-Square Corporation
McHugh Terry
Werner Frank E.
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