JPS5864043A - Positioning device for disc-shaped plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

The present invention relates to a positioning device for a disk-shaped body, which easily aligns orientation flats, which are notches in the semiconductor substrates, at the same angular position in a process of transferring a plurality of semiconductor substrates, and aligns the center of the semiconductor substrates. It is designed so that it can be positioned at a predetermined position. When transferring multiple semiconductor substrates (hereinafter referred to as wafers) between all manufacturing equipment in the semiconductor manufacturing process, the notches around the urchin 6 are aligned at the same angle and positioned at a predetermined position. There is a need. As shown in FIG. 1, the wafer 1 usually has a substantially circular external appearance)
lK is provided with a notch for position detection called orientation flat 2. Therefore, in order to position the wafer 1, manual iR as in the conventional method is used. That is, as shown in Figure 2,
The roller 3.4 is rotating counterclockwise, and the roller 5#i is rotating clockwise. When the outer circumference of the wafer 1 is in contact with the three rollers 3°4.5 at the same time, the wafer 1 rotates in the direction of the hour hand. As a result, the orientation flat 2 eventually reaches a state in which four rollers are separated from the wafer 1 (this position is set to 7 in FIG. 2) - 3.5 rotations). Therefore, the rotation of the sea urchin ^l is stopped and its positioning can be performed. In this case, the wafer 10 was chipped at the periphery), and if the size of the orientation flat 2 is small, an erratic movement occurs and reliable positioning cannot be performed. Also, depending on the size of the wafer 1, three rollers 3,
It is necessary to adjust the relative position of 4.5, and the work involved becomes complicated. On the other hand, a positioning device as shown in FIG. 3 has been proposed to eliminate these drawbacks (Special Feature 11i11).
@55-65445). When positioning the wafer l using the positioning apparatus shown in the figure, first, the output waveform of the reference wafer is stored in the storage unit 11 as digital information. Next, after placing the wafer 1t on the vacuum chuck 7, the centering jig 81 is operated to center the wafer 1. At this time, if the center of the wafer l does not coincide with the rotation axis of the pulse motor 6, the output waveform of the edge sensor 9 when the wafer l rotates once is differentiating circuit 14t-
Generally, it is differentiated. This differential waveform is A/D exchanged and the orientation flat 20 is calculated from the digital information.
The rotation angle position is calculated by the calculation unit 17 of the tuna 2, and based on the calculation result, the position of the orientation flat 2 is roughly matched with the position of the edge center f9. Next, after releasing the holding state of the wafer 1, the centering jig 8t is used again.
- Operate and center Ueno-l. Then, compare the output waveform tube/D-converted digital information of the Edge Sen 10 with the previously stored reference digital information, and minimize the difference in image information. Calculate the rotation angle of the pulse motor 3 as follows,
According to this calculation result, the orientation
- Match the position of the edge sensor 9 to complete the positioning of the wafer l. However, in such a positioning device, when the wafer l is centered, if the center of the wafer l and the rotation axis of the pulse motor 6 are misaligned and fixed, a series of signal processing steps are required to re-center the wafer l. There is the hassle of having to adjust the operation tube and adjust the alignment. In addition, in the semiconductor manufacturing process, in order to prevent contamination lines, it is necessary to reduce the number of contact points, but in addition to the contact between the wafer 1 and the vacuum chuck 7, the positioning device
Since centering is performed by pressing from both sides of the wafer 1 instead of contacting the centering jig 8,
There is also the possibility of damaging the wafer 1, and in this respect it is not preferable as an apparatus for handling semiconductors. The present invention @Fi, In view of the above-mentioned conventional technology, it is an object of the present invention to provide a positioning device for a disc-shaped object such as a wafer that can easily and quickly position a disc-shaped object such as a wafer to a lid at a predetermined position without a centering jig. purpose. The present invention achieves this object by passing through any point at or near the center of a disc-shaped body having an orientation/cheese (7) t, and a straight line perpendicular to the disc-shaped body.
IiI is rotated at least 41 times as the rotation axis, and based on the positional information of the circumference of the disk-shaped body with respect to the rotation angle obtained by this, the deviation of the center of the disk-shaped body from the center of the rotation axis is calculated. The disc-shaped body is calculated as the distance and angle with respect to the center, and this deviation is removed.

[The point at which the disc-shaped body is moved within the plane to which it belongs, and the disc-shaped body is rotated within the plane so as to calculate the deviation of the rotational angular position of the orientation flat from the predetermined rotational angular position and remove this deviation. is the basis of its technical philosophy. Embodiments of the present invention will be described in detail below based on the drawings. As shown in FIG. 4, the wafer is held in a vacuum chuck 18, which is a plate-shaped body having a cutout m called an orie #5 on its outer circumferential surface.
is turned -j by a pulse motor 19 which is a rotating means for tilting. At this time, the pulse motor 19 moves the X direction moving table z
xK is fixed and the screw shaft 2 is driven by the pulse motor 20.
1a) X! parallel to the way l! While moving in the X-axis direction, which is the horizontal direction of the plane, the pulse motor 20 is fixed to the Y-direction moving table 23 and rotates by 2x before rotating the screw shaft 23a as the pulse motor 22 is driven.
It is perpendicular to the Y plane! Move in the axial direction. The wafer 1 is thus able to move freely on the plane to which it belongs. At this time, the pulse motor 19Fi is driven by the pulse motor drive circuit 38, and the pulse motor 20Fi is driven by the pulse motor ffi movement M39.
They are each driven by an Fi pulse motor drive circuit 40. Edge Senna 24. ! S is a device that detects the positional change of the periphery of the wafer 1 as it rotates and outputs position signals B*4 and BH, which are analog signals corresponding to the positional changes, in a straight line in a plane perpendicular to the z-axis. They are placed facing each other so that they lie on a line. These edge sensors 24 and 25 are not particularly limited as long as they have the functions described above, but for example, they have a light emitting part and a light receiving part, and the peripheral part of the wafer 1 is connected between the light emitting part and the light receiving part. It is conceivable to detect the position of the circumference based on the amount of light received by the positioning light receiving section. Furthermore, the position signal 814 of the Edge Center t24°2s
m 88m is converted into a digital signal by the MU/D converter 26 and 27, and the corresponding pulse signal 190 is
The storage unit 28.2 also stores rotation angle information representing the rotation angle tt.
9 and are respectively written and stored. FIG. 5(a) is a waveform diagram showing the position signal 8!4 which is the output signal of the edge sensor +24, and FIG. 5(6) is a waveform diagram showing the position signal 81 which is the output signal of the edge sensor 25. respectively indicate the 20 rotation angle positions of the orientation flat. At the same time, the position signals 8M4 #Bxm are sent to differentiating circuits 80.
31. The signal is passed through the bandpass filter circuits 32 and 33, and further through the rectangular waveforming circuits 34 and 351, where it is converted into digital information representing a rotation angle position of 20 rotation angles of the orientation flat, and is written into the storage units 28 and 29 together with the rotation angle information. It will be remembered. Figure 6 6! L) is a waveform diagram showing the output waveform of the rectangular wave forming circuit 34 corresponding to the nine waveform diagrams obtained by differentiating the protruding portion corresponding to the multi-orientation flat 2 by the differentiating circuit 30. be. Similarly, FIG. 6Cb) Fi differential path and FIG. The first calculation unit 36tj calculates the deviation of the center of the wafer l from the center of the rotation axis of the pulse motor 190 as a distance and angle from the center of the rotation axis of the wafer l based on the contents stored in the storage units 28 and 290. Based on this calculation result, the pulse motor drive circuit 39.40 drives and controls the pulse motor 30.22t so that the deviation is removed. Second calculation unit 37
is the deviation calculated by the first calculation unit 36 and the memory 52
The accurate rotational angle position of the orientation flat 2 is calculated from the position signal 8 of the edge 7 Yt25 stored in the 9. Based on this result, the pulse motor drive circuit 38 rotates and controls the pulse motor 19 to position the orientation flat 2 at a predetermined rotation angle position. The effect of this actual example will be explained in detail along with the manner in which the love is decided. First, it is fixed with a vacuum chuck 18. At this time, there may be a tenth-order deviation between the center of the wafer 1 and the rotation axis of the pulse motor 190 to the extent that the periphery of the wafer 1 does not protrude from the edge sensors 24 and 25 even when the wafer 1 rotates once. The pulse motors 20 and 21t are operated to move the rotating shaft of the pulse motor 19 to the midpoint between the two edge sensors 4 and 25, and then stopped. This will be the initial position. Next, use the pulse motor 1G to rotate the sea urchin 8 le 1, and at this time, the Etsuji Sen? The position signal 8m4°all of 24.25 is digitized into a constant rotation angle and stored in the storage units 28 and 211. on the other hand,
The position signals "84 e jims" are each input to a differentiating circuit 30.
, 31. Through the bandpass filter circuit 32.31, Fig. 6-
) and b), resulting in a differential waveform as shown in the rectangular wave forming circuit 34.
35, a rectangular wave that roughly indicates the position of the orientation flat 2, such as shown in Fig. Next, 1i111
41 calculation 1135, the center of the wafer AI and the pulse motor 19 are determined from the position signal a=a e 11m8 which is the output signal of the edge sensor 24.25 stored in the storage section 28.29 and the above-mentioned Kumi-gata Gikago. Calculate the deviation from the rotation axis. If the mode of this calculation is further improved, as shown in FIG.
It is expressed as the center t-01 of the wafer 1 when the reference point P on the wafer 1 is rotated by θ after the origin is aligned. The reference point P can be set arbitrarily, but it is assumed that it does not change during one rotation of the sea urchin^1. At this time, the distance y and 711 from the origin 0 to the periphery of the wafer l is expressed by the following equation for the portion other than the orientation flat 2. y■-・tsom(1-P)+ iζZshi〒ti・
...(1)7m--woos(topp,)+R''-m
"1sLn" (1-p) ee・(2)ζ Here, - is Oo when point P is exactly on the y-axis, and then it is moved in the direction of the hour hand. Jaku is 9 degrees ^ 10 radius, ・ is the origin O
and the center/center O- of wafer l, P is the angle poo' (
(An example of a counterclockwise direction of the hour hand with respect to a straight line OPK is assumed to be positive). In this case, formula (1) - (2) 2 W-2 ecos (#-p)
That is, the edge sensor 24.25 t(I J
j Bsam Isa j The difference becomes an accurate cosine wave of -1 to 2 in the portions other than the orientation flat 2. This waveform is shown in Figure 9. On the other hand, (1) formula x
(2) The formula becomes 1. That is, edge sensor 24.
The product of the position signals 8-4t811 of 25 has a constant value in areas other than the orientation flat 2, regardless of the rotation angle of the wafer 10!1. This waveform is shown in FIG. Then, the position signals 8fi4sllll of the portions other than the orientation flat 2 are stored in the storage units 28 and 29.
For the output waveform selected based on 1% of the data stored in
Find the deviation. That is, the deviation distance e and the angle 1! f
t- is given as information representing. Pulse motor drive circuit 3 based on the deviation determined as shown in ! ), 40
Pulse motor 20.22 tube driven through the Urchin JSL
align the center with a predetermined position. On the other hand, the orientation flat 2 is calculated by comparing the position signal 1hl, which is the output signal of the edge sensor 25 stored in the storage unit 29, with the equation (2) in the calculation unit 37 of the 2nd position.
The first rotation angle position tjEiiK is calculated. To comment further,
In addition to the information representing the distance and angle tp from the first calculation unit w436, the wafer 1 is calculated from the product of the stored contents selected from the storage unit 28 and 29 and the previously determined distance.
Information representing the radius R of is output, and based on this, the distance @ysat at an arbitrary angle is calculated, and by comparing that value with the contents of :till in the storage unit 290, it is determined that the range where the two values differ is 20 rotations of the orientation flat. angle l
11t - Can be accurately identified. Based on Sotojin's calculation results, pulse motor trunk movement 1m path $
At 8t-t, the pulse motor 19 is driven to align the orientation flat 2 with a predetermined rotation angle position, thereby completing the predetermined positioning of the sea urchin ^1. In addition, in the above detailed example, the calculation unit 36 of the wire 2 calculates the position signal 818, which is the output signal of the edge sensor 25, and the theoretical formula (
2) The position of the orientation flat 20 was determined by comparing with the formula, but the waveform was corrected based on the value calculated using the same method in the first calculation unit 36 by rotating the standard sea urchin ^t11. The rotational angle position of the orientation flat 2- can also be calculated by storing this value in the new storage unit as a fist value, and by using this value, the edge senna 25 digit 11 signal B i and t comparison calculation. Furthermore, the object to be positioned is not limited to the wafer 1, but it is possible to obtain similar effects with any of the four types of disc-shaped bodies. As explained above in conjunction with the above examples, according to the present invention, the center of the disc-shaped body having an orientation flat, which is a notch provided in the outer part, and the center of the rotation axis for rotating the orientation flat. Since the disc-shaped body is positioned by calculating the disc-shaped body based on the calculated value, it is possible to position the disc-shaped body without using a centering jig. At this time, the only contact with the H-plate shaped body is the vacuum chuck, and the semiconductor substrate O
ct decision KFi is very suitable and 2i1. Furthermore, even if the disc-shaped body is
It has the advantage of being able to move in the same direction as the pill, which greatly reduces the transfer time. Simple and sharp table drawings Figure 1 is an external view of a semiconductor substrate (wafer), Figure 12 is an explanatory diagram for explaining the positioning means according to the prior art, 11
1!3Il! 1#i Prior art (block diagram showing another such positioning device t'', FIG. 4 is a block diagram showing the actual embodiment of the present invention, aS diagram-), No. 58i! 6I) Fiets/- Waveform diagrams showing the output waveforms of 124 and 25, respectively;
#! Figure 6 (a), 1) Fi is a waveform diagram showing the image waveforms of those waveforms, Figure 7-), υ is based on them (the waveform showing the rectangle flIt - 1 #! 8 is the calculation unit ll in the above embodiment) [
Explanatory diagram for explaining, Figure 9 Welfare Edge Senna 24.2
Waveform diagram showing the waveform when taking the difference between the outputs of 5, No. 10
WJ is an flt-type diagram showing a waveform in a good case when the outputs of the edge sensors 24 and 25 are multiplied. In the diagram, l is a conductor base & (wafer), 2#i orientation flat, 111 is a vacuum chuck, 19.20.22#i pulse printer, z4. zs is an edge sensor, 28.29 is a storage section, asFi first arithmetic section, and 37 is a second arithmetic section. Patent applicant: Nippon Telegraph and Telephone Public Corporation Representative: Patent attorney Shibe Mitsuishi (and 1 other person) Figure 1 Figure 2 Figure 3 Figure 4 Figure 7 Figure 6 Fig. 8 Fig. 9 - ``Mackerel (!I)' Fig. 10 □ Times (skin)

Claims (1)

[Claims] In a device for positioning a disc-shaped body having an orientation flat which is a notch in a part of the outer periphery, the disc-shaped body is held at an arbitrary position and at any point at or near the center of the disc-shaped body. A rotating means capable of making at least one rotation and stopping at a predetermined rotational angle position as a rotational axis perpendicular to the disc-shaped body; and a rotating shaft KiI of this rotating means! a pair of edge sensors 9 disposed opposite to each other on a straight line in a straight plane, detecting the positional change of the peripheral edge of the disc-shaped body as it rotates, and outputting a position signal corresponding thereto; a memory section that stores position signals output by each edge sensor not related to the rotation of the disk-shaped body, together with corresponding rotation angle information; and storage contents of these storage sections talc inside the disk-shaped body. a fifth calculation unit that calculates the deviation t from the center of the rotation axis, and a fifth calculation unit that calculates the distance and angle with respect to the center of the rotation axis; a moving means for moving the disc-shaped body (by moving the disc-shaped body), and calculates the rotational angular position of the orientation flat of the disc-shaped body based on the storage content tI& of the storage unit, and moves the disc-shaped body to a predetermined rotation angle by moving the disc-shaped body. 1. A positioning device for a disc-shaped body, comprising: a second arithmetic device for determining a position.