JPS6199345A - Wafer position detector - Google Patents

Abstract

PURPOSE:To detect the position of a wafer accurately, by providing photosensors, which detect laser light inputted to a glass rod, on the upper and lower sides of the glass rod. CONSTITUTION:The basic structure of a wafer-position detecting mechanism is composed of a laser source 16; a glass rod, which is arranged at the back side of a cassette 6; a mirror 17, which reflects the laser light 20 emitted from the laser source 16 to the glass rod 18; and photosensors 19 and 19',which detect the inputted laser light to the glass rod. When, e.g., a wafer hand 5 moves from the upper side to the lower side and the wafer is located at the part between them, the laser light 20 is shielded by the wafer and not inputted to the rod 18. The sensor does not detect the light. When the wafer is not present, the photosensor 19 detects the light inputted to the rod 18. Therefore, the position, where the detected light has the least value, is the central position of the wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wafer position detecting device, and particularly to a wafer position detecting device conveniently used in a wafer transport device.

A carrier capable of storing a plurality of wafers is installed in the main body of the apparatus which processes or measures wafers at once. The wafer is supplied from the intermediate carrier to the main body of the apparatus, where processing or measurement is completed, and after t, the wafer is stored in the carrier again and sent to the next process together with the carrier.

Conventionally, belt conveyor-type conveyance devices and hand-type conveyance devices have been used to carry wafers in and out of carriers. Figure 1 schematically shows a known pantograph handler. This handler includes a hunt arm 1 which is rotatable around a shaft 3 provided at one end, a hand arm 2 whose one end is also rotatably connected to the other end of the hand arm 1 via @4, The other end of the hand arm 2 is also pivotably connected to a finger 5 for supporting the original wafer. Note that the handler has two hand arms 1 and two hand arms 2, each having k pairs.

In FIG. 1, the hand arm 1 and the hunt arm 2 are extended in a straight line, and the hand arm 1 and the hunt arm 2 are housed in a wafer cassette 6, with the finger 5 positioned on the back side of the wafer 7, and shown in its original state. On the other hand, Figure vg2 is a diagram showing the original state in which the finger 5 is retracted toward the shaft 3 with the position of the shaft 3 as a fixed point, and the wafer 7 is taken out from the wafer cassette drawer. Here, the hand arm 2 rotates so as to bend around @4 as the t-arm rotates 10 times around the axis 5, while the other end of the hand arm 2 also rotates around the axis 5.
The finger 5 rotates around the finger 5. Finally, hand arm 1 and hand arm 2 are moved to a position where the arms 1 and 2 are aligned and the paired arms face each other in a straight line.

According to the configuration of the t-handler described above, the hand arm needs to have a length that is half the predetermined travel distance of the wafer. Furthermore, when the wafer is rotated for reasons such as removing it from the carrier and feeding it into the main body of the apparatus, the exposed arm 1 and hand arm 2 overlap, and the paired arms rotate in a state where they face each other in a straight line. , it is necessary to change the position of the Uni-No placed on the finger surface. The occupied area required for the operation of this master handler becomes large.

In addition, the conventional handler must be equipped with a mechanism that allows the hand arms 1 and 2 to tilt at the same angle with respect to the fingers.

Furthermore, although a plurality of wafers are usually stored in the carrier, it is necessary to accurately detect the position of one wafer in order to insert the finger between the desired wafer to be carried out and the adjacent wafer. . Therefore, it is preferable to incorporate a wafer Rfjt detection mechanism into the wafer handler.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a position sensing mechanism that can be conveniently used in a wafer transfer device.

The handler of the wafer transfer device in which the position detection device is conveniently incorporated into the handler of the present invention is provided at one end of the t-axis 9.
A hand arm 10 which is rotatable about the center, one end of which is rotatably connected to the other end of the hand arm 10 via a shaft 11, and a hand arm 12 which is rotatably connected to the other end of the hand arm 12. It is composed of wafer supporting fingers 5 which are freely connected. The handler has two hand arms 10 and two hand arms 12 separated from each other in pairs.

The third case is shown with the hand arm 10 and the hand arm 12 extending in a straight line, housed in the wafer cassette 6, and with the fingers 5 positioned on the back side of the nine wafers 7. On the other hand, in the fourth south, the finger 5 is retracted toward the axis 9 with the position of I11]9 as a fixed point, and the wafer 7 is taken out from the wafer cassette 6 (2). Here, the hand arm 12 rotates so as to bend around the shaft 11 in accordance with the rotation of the arm 10 around the shaft 9, and at this time, the other end of the hand arm 12 also rotates around the shaft 13 with respect to the finger 5. Rotate. On the way, the arms 10 and 12 overlap and move to a position where the paired arms face each other in a straight line (see FIG. 2).

In the handler of this wafer transfer device, the hand arm 12 moves three times around @11 from the position shown in FIG. 2 in a direction that intersects with the wafer cassette 6. Finally, hand arm 10 and hand arm 12 are
Finger 5 extends in a -KIR shape in the opposite direction to the state shown in the figure.
are located above hand arms 10 and 12 so as to overlap. Therefore, in the case of this handler, compared to the conventional handler shown in FIG. 1, the length of the hand arm is only one quarter of the predetermined travel distance of the wafer, making it extremely compact.

Further, as shown in FIG. 4, most of the arms 1o and 12 are placed on the surface of the finger 5 and are located directly below the wafer 7, so the handler is rotated in order to move the wafer 7 in a desired direction. Occupancy iW+ required when
nt is extremely small.

A mechanism that enables the operation of the hand arms 1o and 12 as described above will now be described with reference to FIG. 5.

The shaft 9 is constructed integrally with the arm 10, and a pulley 14 is fitted inside the shaft 9. - the horizontal axis 11 consists of a pulley which is integral with the arm 12, and the pulley 14
A timing belt 15 is installed between the pulley 11 and the timing belt 15. Therefore, rotate the pulley 14 [? When # is set, the driving force is transmitted to the pulley 11 via the timing belt 15.

Here, when the finger 5 is pulled in the direction toward the axis 9 and moved linearly, the inclination angle of the arm 10 and the opening angle of the arm 10 and the arm 12 always maintain a 1:2 relationship. The driving force of the pulley 14 must be determined accordingly.

Nos. 6 and 70 are a side view and a plan view, respectively, of an embodiment in which a wafer handler of the present invention incorporates a sea urchin position f1m detection mechanism. As mentioned above, a plurality of wafers 7 are stored in the cassette 6, and the finger 5 is placed between the desired wafer 7 to be carried out and the adjacent wafer 7 (
In order to insert the wafer, it is necessary to know the exact position of the wafer. Therefore, it is preferable to use a wafer position detection mechanism built into the wafer handler. The basic configuration of the wafer vertical clamping machine ladder of the present invention includes a laser rP, 16,
A glass rod 18 disposed on the side of the cassette 60,
A laser 20 emitted from a laser source 16 is connected to a glass rod 1.
8, a mirror 17, a narrow photo sensor 19 that detects the laser beam incident on the glass slot, and 1.
9'. The glass mud 18 is made by roughening a part of a cylindrical glass. The upper part of the one facing south is cut at right angles to the glass, but it is preferable to coat that part with a reflective film. Furthermore, the entire loft may be coated with a reflecting mirror, and only the incident portion may be cut into a slit shape. In order to eliminate the need for vertical correction due to the difference in level between the finger 5 and the laser optical path, it is preferable to make the levels of the finger 5 and the laser optical path very close to each other. ! Note that the reason for using a laser as a light source is that lasers have excellent straightness and are suitable for detecting the position of linear objects, according to Minato et al. With the above configuration, when the wafer hand 8 moves from above to below, if a wafer exists between them, the laser source 20 will be blocked by the wafer and will not enter the rod 18 and the photosensor 19 will not detect the light.

If there is no wafer, the photo sensor 19 enters the rod 1B and detects the multiplication table. Therefore, the position where the least amount of detected light is detected becomes the central position to the sea urchin. This relationship? It is shown in FIG.

FIG. 8 shows the relationship between the intensity of light detected by the photosensor 19 provided at one end of the glass rod 18 and the height direction of the handler. It can be seen that as the height of the handler changes 9 and the incident position of the laser source 20 becomes farther away from the photo sensor, the light reaching the senna becomes weaker and its amplitude becomes smaller. Therefore, if the photo sensor is provided only at the upper end of the glass slot, the output relationship will be as shown in FIG. 8, and it can be imagined that it will be difficult to detect the wafer position when the handler comes downward. The present invention was made to solve this problem, and it detects the position of the glass rod by installing photo sensors at both ends of the glass rod and adding the respective photo detection signals and using a composite signal. It is. That is,
If the photo sensor output on one end becomes weak, the sensor output on the opposite side becomes strong, so by adding them together, it becomes possible to detect the position accurately with constant changes. No. 9- shows a signal synthesis circuit, in (9) AI and AI' are current-voltage conversion circuits that convert the charging current of the photosensor 19, 19' into voltage, and A2#i is an addition circuit that adds them. When a light source other than a laser, such as I or KD, is used as a light source, the light from the light source spreads to some extent, so it is necessary to use this spread light to detect that the desired wafer whose position is to be detected blocks the optical path. is extremely difficult.

There are other ways to view the cross section of the sea urchin using the TV left camera, but if you use the TV left camera, you will need to focus the camera lens.

However, when the wafer is stored in a cassette, the position of the wafer varies considerably in the loading/unloading direction.
This makes it impossible to perform accurate pointless alignment, making it unsuitable for precise position detection. Additionally, TV cameras are expensive, large and complex.

In short, the wafer position detection method using a laser not only has an @-linear optical path, so there is no influence from adjacent wafers above and below, but also does not require focusing, so it can detect the position of wafers along the direction in which the stored wafers are taken in and out. There is no decrease in detection accuracy due to variations in the t position.Furthermore, since this position detection method utilizes the parallel and straight traveling property of the laser beam, it is possible to increase the diameter of the wafer (
is also suitable. A further advantage of this position detection method is that alignment of the optical system for detecting the intensity of the transmitted laser light is extremely easy.

Here, reference numeral 21 is a hand arm extension/contraction drive section for bending the hand arms 10 and 12 in order to extract the finger 5 from the cassette 6. Reference number 2
Reference numeral 2 denotes a handler rotation motor used to rotate the handler in order to change the direction of the rL wafer placed on the surface of the finger 5.

Furthermore, reference numeral 25 is a handler elevating mechanism, which can change the height of the fingers 5 to a desired level in order to remove the wafer 7 housed in the cassette 6 at any position.

[Brief explanation of the drawing]

Figure 1 shows a conventional handler in an extended state, Figure 2 shows a folded state of the first handler (indicated by 11), and Figure 3 shows a handler of a conveying device in an extended state. Figure 4 shows the handler in Figure 3 in a folded state.
Figure 5 (9) shows the pivot mechanism of the arm of the handler as shown in the Wc3 diagram. Incorporated fruit '1
Side view □□□ of the example and top view 1, That's 5...
...Finger 9...Axle 10.12...Hand arm 11.14...Pulley 15...Timing belt

Claims (1)

[Claims] A laser source, a mirror that directs the laser beam emitted from the laser source toward the cross-sectional direction of the wafer, a glass rod that guides the emitted laser beam, and a photo sensor that detects the laser beam that has entered the glass rod. Wafer position detection devices located above and below the wafer.