Optics: measuring and testing – Position or displacement
Reexamination Certificate
2003-03-13
2004-03-23
Pham, Hoa Q. (Department: 2877)
Optics: measuring and testing
Position or displacement
C250S559360, C414S936000
Reexamination Certificate
active
06710887
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a testing device for establishing the position of a notch or a bump on a disk, such as a wafer, for example, and a method for establishing this position on the disk.
In the production of integrated circuits, for reducing the throughput times and for lowering the number of rejected wafers, it is desirable to present the wafers to the operators using the transporting system in such a way that the wafers are aligned in a specific manner on the wafer lifts. For this purpose, a notch is cut into the wafer at a specific point. However, it is also conceivable to provide a projecting bump. Notches or bumps are always located in a predetermined position, which is identical for all wafers, in relation to the integrated circuits. The alignment usually takes place in this case by insuring that the notches or bumps are at 12 o'clock, or in other words, at the top, when the wafers are viewed laterally in a wafer mount. The presentation of such aligned wafers dispenses with the need for the operation of carrying out an alignment on what is known as the notch finder, which leads to a saving in terms of distance covered and time, and also makes it possible for the operators to carry out batch number checks immediately, so that the risk of batches being mixed up is reduced.
The alignment of the wafers takes place on a notch finder. This is a device that is capable of turning the wafer until the notch or the bump is located in the predetermined position. However, it was previously not possible to carry out automatic checking of the correct alignment of a notch or bump during the transporting of the wafers, let alone to correct this alignment.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a testing device, a transporting system, and a method for establishing the position of a notch or a bump on a disk, which overcomes disadvantages of the prior art apparatus and methods of this general type.
In particular, it is an object of the invention to provide a testing device for checking the alignment, as indicated by notches or bumps, of disk-shaped workpieces, such as wafers for example. The disk-shaped workpieces will be referred to as disks.
An important requirement for the testing device is that it must not interrupt the transport flow of the disks and consequently must perform the test quickly and without contact. The invention is therefore based on the principle of being able to determine the presence of disks, or notches or bumps on a disk edge, by using reflected light. The testing device can be used for any desired types of disks, so is not restricted to wafers.
With the foregoing and other objects in view there is provided, in accordance with the invention, a testing device for establishing a position of a notch or bump on an edge of a disk. The testing device includes: a testing area for positioning the disk to be tested thereon; a light source configured for illuminating the edge of the disk; a first light sensor configured for receiving light of the light source reflected by the edge of the disk; a second light sensor configured for receiving light of the light source reflected by the notch or the bump of the disk if the notch or the bump is located within a predetermined positional area; and an assessment unit for establishing whether the disk is positioned in the testing area based on light falling onto the first light sensor. The assessment unit is for establishing whether the notch or the bump of the disk is located within the predetermined position based on light falling onto the second light sensor.
In accordance with an added feature of the invention, the testing area is part of a transporting line for transporting the disk.
In accordance with an additional feature of the invention, a signaling device signals placement of the notch or the bump determined by testing the disk.
In accordance with another feature of the invention, a control unit is provided for controlling a transport flow of the disk dependent on a position of the notch or the bump determined by testing the disk.
In accordance with a further feature of the invention, there is provided, an alignment unit for aligning the notch or the bump of the disk dependent on a position of the notch or the bump determined by testing the disk; and a control unit for controlling the alignment unit.
In accordance with a further added feature of the invention, there is provided, a common housing. The light source and a light sensor, which is either the first light sensor or the second light sensor is unified in the common housing. The common housing is configured such that an axis of a light beam radiated from the light source impinges perpendicularly onto the edge of the disk or perpendicularly onto at least part of the notch or the bump and can be received by the light sensor in the common housing.
In accordance with a further additional feature of the invention, there is provided, an assessment unit for determining whether notches or bumps of a group of disks that are being transported together and that are being successively tested lie within the predetermined positional area.
In accordance with yet an added feature of the invention, there is provided, a common transporting device for transporting the group of disks.
In accordance with yet an additional feature of the invention, the disk is a wafer for semiconductor production.
With the foregoing and other objects in view there is also provided, in accordance with the invention, a method for establishing a position of a notch or a bump on a disk. The method includes steps of: illuminating a testing area with a light source configured for illuminating the edge of the disk; measuring light reflected by the edge if the disk is located in the testing area; measuring light reflected by the notch or the bump if the notch or the bump of the disk is located within a predetermined position; and based on the step of measuring light, establishing whether the disk is located in the testing area and establishing whether the notch or the bump of the disk is located within the predetermined position.
In accordance with an added feature of the invention, the method includes a step of establishing whether a group of disks are present in the testing area, and establishing positions for the disks of the group.
In accordance with an additional feature of the invention, the method includes a step of activating an alignment unit for aligning the notch or the bump of the disk dependent upon a position of the notch or the bump determined by testing the disk.
In accordance with another feature of the invention, the method includes a step of activating a transport control for influencing a path of the disk, dependent upon a position of the notch or the bump determined by testing the disk.
In accordance with a further feature of the invention, the method includes a step of activating a transport control for influencing a path of a group of disks, dependent upon a variable calculated from positions of notches or bumps of the group of disks.
With the foregoing and other objects in view there is provided, in accordance with the invention, a transporting system for transporting disks. The transporting system includes a testing device for establishing a position of a notch or bump on a disk. The testing device includes: a testing area for positioning thereon at least one disk to be tested, the disk having an edge with a notch or a bump; a light source configured for illuminating the edge of the disk; a first light sensor configured for receiving light of the light source reflected by the edge of the disk; a second light sensor configured for receiving light of the light source reflected by the notch or the bump of the disk if the notch or the bump is located within a predetermined positional area; and an assessment unit for establishing whether the disk is positioned in the testing area based on light falling onto the first light sensor. The assessment unit is also for establishing whether the
Greenberg Laurence A.
Infineon - Technologies AG
Mayback Gregory L.
Pham Hoa Q.
Stemer Werner H.
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