JPH06135506A - Wafer conveyance device - Google Patents

Abstract

PURPOSE:To surely make the conveyance of wafer possible by detecting that wafer is set on a cassette properly and controlling the conveyance. CONSTITUTION:A cassette 5a is lowered and opposed to an inner arm 3 so that a wafer 14a which is not exposed to light is taken out of the lowest step pocket of the cassette in order to detect presence of non-detected wafer by laser detection devices 6a, 6b. Here, the cassette 5a is moved relatively by the wafer detection devices 6a, bb which use laser having thin beam diameter and an ascent and descent drive device 7 which has the position detection function to detect oblique and double wafers by operating and processing detection signal and position information and interrupt the conveyance to give the assist demand. The relative position of the cassette 5a for the inner arm 3 is calculated, the cassette 5a is lifted and lowered to the adequate position in which the inner arm 3 advances by the ascent and descent drive device 7, and a wafer 14a is adsorbed in the inner arm 3 and pulled out. Thus, it is possible to convey wafer without breaking it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of manufacturing semiconductor devices, and more particularly to improvements in semiconductor wafer transfer devices.

[0002]

2. Description of the Related Art Conventionally, a method of detecting and unloading a wafer in a wafer cassette in a wafer transfer apparatus of this type has been carried out by a wafer cassette and a photoelectric sensor which move relative to each other, and a transfer arm installed to face the wafer cassette. The presence / absence of a wafer in the wafer cassette is detected by the light entering / blocking state of the photoelectric sensor, and the transfer arm moves in at a specified height to carry out the wafer.

[0003]

In the above-mentioned prior art, it is impossible to detect only the presence / absence of a wafer in the wafer cassette, determine whether the wafer is correctly installed, and the relative height of the wafer with respect to the transfer arm.

The object of the present invention is to accurately detect the presence / absence of a wafer in a wafer cassette, determine whether the wafer is correctly installed, and detect the relative position with respect to the transfer arm,
An object of the present invention is to provide a wafer transfer device that can reliably carry out a wafer.

[0005]

In the above prior art, the presence or absence of the wafer in the wafer cassette can be detected but the correct installation is possible because the light beam diameter of the wafer detection system is too wide relative to the wafer interval. Determination of whether or not,
Further, it is impossible to detect the relative height between the transfer arm and the wafer in the wafer cassette.

In order to achieve the above object, in the present invention, a thin light beam, for example, a laser beam is adopted for the wafer detection system, and a position-detectable encoder is provided as means for moving the detection optical system and the wafer cassette relatively. A motor (or a pulse motor) is used and is configured to be comprehensively controlled by a control device including a CPU that calculates the relative height with respect to the transfer arm.

[0007]

Operation: First, when detecting the presence or absence of wafers in the cassette,
While moving the detection optical system and the cassette relative to each other, it is determined whether or not a wafer is present and whether the wafer is properly installed,
When there is a wafer, the relative height between the cassette and the transfer arm is calculated using the position detecting means of the motor, and when the wafer is unloaded by the transfer arm, the relative height information is fed back to carry out the wafer unloading. It becomes possible to perform surely.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wafer transfer device of a reduction projection exposure apparatus will be described below with reference to the drawings as an embodiment of the present invention. In FIG. 1, the transfer arm has a vacuum suction portion at its tip so that two sides facing the wafer can be picked up, and the outer arms 2a and 2b are linearly driven so that they can move in and out in synchronism with each other.
And an inner arm 3 that has a vacuum suction part for picking up the side sandwiched between the two sides of the wafer or the center, and is linearly driven to move in and out. (Not shown). On the other hand, the cassette table 4 is provided with cassettes 5a and 5b capable of accommodating 25 wafers each, and has detection optical systems 6a and 6b for detecting the presence / absence of wafers in the cassette. An elevating and lowering drive mechanism 7 having a position detecting function is provided in each cassette so that the cassettes are sequentially drawn out in a face-to-face manner and returned to their original pockets after the exposure is completed.
Further, a horizontal drive mechanism (not shown) for the cassette is provided so that the cassette slides into the wafer unloading position. On the other hand, on the orientation flat alignment table 8 for aligning the orientation flat (hereinafter referred to as "orientation flat") direction of the wafer, a rotary table 9 for raising the received wafer to receive it by vacuum suction and rotate it, and an optical device on the outer edge of the wafer in synchronization with the rotation. An orientation flat detector 10 is provided which is configured to detect the orientation flat direction by detecting an image and adjust the orientation flat direction by rotating the rotary table by a considerable amount. Next, the exposure stage 11 includes the outer arms 2a and 2b.
A set of three pins 13 having a wafer elevating function is provided to raise and receive the wafer conveyed by, to descend after arm retreat, and to transfer it to the wafer chuck 12. It is introduced under an exposure optical system (not shown), and is configured to obtain an array of original images on the wafer by repeating exposure of the original image and step movement of the stage, that is, the wafer adsorbed on the stage. Each of the above elements is configured to be integrally controlled by a control device (not shown) including a CPU.

Next, the wafer transfer operation will be described.
First, as shown in FIG. 2, in order to take out the unexposed wafer 14a from the lowermost pocket of the cassette, the cassette 5a descends and directly faces the inner arm 3. Next, the presence / absence of a wafer to be detected is detected by the laser detection systems 6a and 6b, and the relative height between the inner arm 3 and the wafer is calculated by a cassette lifting mechanism having a position detecting function.

Wafer detection will be described with reference to FIG. If the wafer is not installed correctly in the wafer cassette (eg diagonal wafer, double wafer, etc.), the conventional detection system can only determine the presence or absence of the wafer, so when the wafer is unloaded from the cassette, it may collide with the transfer arm, etc.
Or it has led to damage to the device. When a laser having a small beam diameter is used in the wafer detection system as in this embodiment and the angle between the wafer to be detected and the laser optical axis in the wafer detection system is made small (about 0.5 ° to 1 °), the wafer Since the detection signal becomes sharp, the cassettes 5a are moved relative to each other by the detection systems 6a and 6b and the elevating mechanism 7 having a position detection function, and arithmetic processing is performed on the detection signals and position information to detect diagonal wafers, double wafers, etc. The detection becomes possible, and a measure is taken such as interrupting the carrying operation and issuing an assist request.

The cassette 5 for the inner arm 3
The relative position of a is calculated, the cassette 5a is moved up and down to an appropriate position where the inner arm 3 enters by the lifting drive mechanism 7 having a position detection function, and the inner arm is advanced, the cassette is lowered, the inner arm is sucked, and the inner arm is retracted. Wafer 14 on inner arm 3
Adsorb and pull out a. Next, the entire transfer arm 1 rotates 90 degrees to face the orientation flat alignment table 8, and the inner arm 3, that is, the wafer 14a adsorbed to this is admitted and released, the rotary table is raised, the wafer is adsorbed, and the arm is retracted in this order. The wafer 14a is carried into the orientation flat alignment table 8. After the wafer is aligned by the operations of the rotary table 9 and the orientation flat detector 10, the wafer is adsorbed to the outer arms 2a and 2b in the order of descending positioning of the transfer arm, entry of the outer arm, release of adsorption of the rotary table, and descending. 1
Is raised and is rotated by 90 degrees again, and is conveyed onto the exposure stage 11. In FIGS. 3 and 4, the wafer 14a transferred onto the exposure stage 11 is the first wafer in the cassette 5a, and immediately the transfer arm is positioned downward, the outer arms 2a and 2b are released from suction, and the pins 13 are lifted to support the wafer. The arms 2a and 2b are moved backward in this order, the pins 13, that is, the wafer supported by the pins is lowered, and the wafer chuck 12 is sucked.
The transfer arm 1 rotates 180 degrees and moves to the next wafer unloading operation. Next, when carrying the second and subsequent wafers, it is necessary to first unload the exposed wafer 14a. In FIG. 4, the exposed wafer 14a is pushed up by the pin 13, the inner arm 3 enters, the pin 13 descends, and the inner arm 3 moves.
After the wafer is attracted to the inner arm 3 and the inner arm 3, that is, the wafer attracted to the inner arm 3 is retracted (unloaded; dotted line in FIG. 3), the unexposed wafer 14b is loaded, and then the transfer arm 1 is carried out.
Is rotated 180 degrees, the exposed wafer 14a adsorbed to the inner arm 3 is returned to the original height position of the inner arm 3 and the cassette when the wafer is initially carried out to the original pocket from which the cassette 5a is taken out, and then the The next wafer transfer operation starts.

In the same manner, 25 wafers in one cassette are transferred, and after the exposure process is completed, the horizontal drive mechanism switches to the other cassette, and the cassette 25 is again processed in the same manner.
Transfer a wafer. Further, if new cassettes are sequentially exchanged, the above operation is repeated.

Although this embodiment has been described as an example in which a laser is used for the wafer detection system, the photoelectric sensor 1 as shown in FIG.
The same effect can be obtained with an optical system in which 5, 16 and the multi-slit 17 are combined.

Although this embodiment has been described as a wafer transfer apparatus for a reduction projection exposure apparatus, the wafer transfer apparatus is necessary for all apparatuses that process wafers. It can be easily used for other exposure equipment using X-rays and X-rays, wafer processing equipment such as etching equipment and ion implantation equipment, resist coating, developing equipment, wafer observation by light or electron beam, and measurement equipment. .

[0015]

As described above, according to the present invention, since an oblique wafer, a double wafer and the like can be detected, the wafer and the device are not destroyed.
Further, even if the cassette pocket is deformed, it can be carried in and out from the optimum position, so that highly reliable transfer can be performed, and therefore, there is an effect that it can contribute to the improvement of the reliability of the wafer transfer device.

[Brief description of drawings]

FIG. 1 is a plan view of a wafer transfer device of a reduction projection exposure apparatus that is an embodiment of the present invention.

FIG. 2 is a sectional view taken along line I-I of FIG.

FIG. 3 is a plan view of a state different from FIG.

FIG. 4 is a view on arrow A in FIG.

FIG. 5 is a diagram showing a relationship between a wafer storage state and detection signals.

FIG. 6 is a diagram showing another example of a wafer detection system in a cassette.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transfer arm, 2a, 2b ... Outer arm, 3 ... Inner arm, 4 ... Cassette table, 5a, 5b ... Wafer cassette, 6a, 6b ... Wafer detection system, 7 ... Lifting drive mechanism, 8
… Orientation flat alignment table, 9… Rotary table, 10…
Orientation flat detector, 11 ... Stage, 12 ... Wafer chuck, 13 ... Pin, 14a, 14b ... Wafer, 15 ... Light emitting part (LED as an example), 16 ... Light receiving amplifier, 17 ... Multi-slit.

Claims (2)

[Claims] 1. A wafer detection system comprising a detection light beam and a photodetector, which are sufficiently smaller than a wafer interval in the cassette in a wafer transfer device for loading and unloading a wafer from a wafer cassette.
A wafer transfer apparatus comprising means for relatively moving the detection system and a cassette (wafer), and configured to detect that the wafer is correctly installed in the cassette and control transfer. 2. A wafer transfer apparatus according to claim 1, wherein the wafer transfer apparatus is configured to detect a relative position of a wafer and control an in / out position of a transfer arm.