JPH06249640A - Noncontact positioning device for plate-like body - Google Patents

Abstract

PURPOSE:To perform noncontact position detection of a wafer in such a state that there is no possibility of foreign matters falling onto the upper surface of the wafer by detecting the collision of converged energy rays with the edge of the wafer. CONSTITUTION:A plurality of converged light rays 16a-16h are radiated in the direction in which the light rays 16a-16h are gradually converged or scattered along a center axis and the light rays 16a-16h are respectively detected by means of photodetectors 15a-15h. A wafer 12 is held by means of a hand 13a in a plane which is nearly perpendicular to the center axis and one of a sensor unit 17 and the wafer 12 is moved or rotated relatively to the other by means of a pulse motor 7 so that the edge of the wafer 12 can come into contact with the converged light rays 16-16n. Then the positions of the light rays 16a-16h are found from the height at which the light rays 16a-16h are first intercepted and the positional deviation of the wafer 12 is further found. In addition, any one of the emitting means or detecting means positioned above the wafer 12 in the vertical direction is installed to the outside of the periphery of the wafer 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for contactlessly positioning a plate-like body (wafer) without dropping dust or the like onto it.

For example, in a method of manufacturing a semiconductor device, there are many steps for automatically carrying a semiconductor wafer. In these transfer steps, in order to accurately transfer the semiconductor wafer to a desired position without damaging the semiconductor wafer, dust or the like should be attached to the predetermined position accurately and without giving a mechanical shock. Instead, a technology for prompt placement is required.

[0003]

2. Description of the Related Art A conventional non-contact positioning device for a silicon wafer or the like moves a wafer of a predetermined size in a direction parallel to its main surface and fixes it stationary by a plurality of photocouplers (a light emitting element and a light receiving element). Position detection by a sensor unit composed of (a combination of), or by detecting the position by a sensor unit that moves a stationary and fixed wafer of a predetermined size in a direction parallel to the main surface of the wafer,
The position was set to a predetermined position.

[0004] As an example showing such a conventional technique, a technical magazine "Automation Technology" Vol. 19, No. 8 (1987) pp.
54 to 60 and Japanese Patent Publication No. 61-3637.

[0005]

In the above-mentioned prior art, the sensor unit or a part of the sensor unit is arranged right above the wafer to be positioned, and downflow in the clean room occurs. It does not reach, dust and minute particles in the atmosphere accumulate there,
Foreign matter may fall and adhere to the upper surface of the wafer directly below.

Further, the structures of these devices are such that the downflow airflow is disturbed in the clean room, or the downflow airflow is blocked. Furthermore, if an attempt is made to detect a wafer having a size different from that of a wafer of a predetermined size, the moving distance of the wafer or the sensor unit required for the detection becomes large, the position detection takes time, and the moving mechanism becomes large. Will end up.

Even if the number of optical sensors is increased so that the position detection of wafers of various sizes can be completed in a short time in order to solve this point, the arrangement and wiring of a large number of optical sensors, and further The device becomes complicated in terms of a detection result processing circuit and the like.

An object of the present invention is to perform non-contact positioning of a wafer having a simple structure capable of accurately and promptly responding to position detection of wafers of various shapes and sizes without foreign matter falling onto the upper surface of the wafer. To provide a device.

[0009]

A feature of the present invention that achieves the above object is that a sensor detects that a focused energy line composed of an electromagnetic wave or a sound wave having a strong directivity is in contact with an edge of a wafer. A sensor unit having an emission means for radiating a plurality of focused energy rays in a direction in which they converge or diverge gradually along a central axis in a non-contact positioning of a wafer and a detection means for detecting the radiated energy rays, respectively. A means for holding the wafer in a plane substantially perpendicular to the central axis, and one of the sensor unit and the wafer relative to the other so that the edge of the wafer contacts each of the focused energy rays. A means for moving or rotating, which is positioned vertically above the plate-like body in both the emission means and the detection means. Shall is to be installed from an edge of the plate-like body on the outside.

[0010]

Function: While radiating a plurality of focused energy rays in the direction of gradually converging or diverging along the central axis, the plate-shaped body is held in a plane substantially perpendicular to the central axis, and the plate-shaped body or the sensor unit. When is relatively moved or rotated along the central axis, each of the plurality of focused energy rays can be blocked by the edge of the plate-shaped body.

When the height of the plate-like body is changed, the position on each focused energy ray is obtained from the height at which each focused energy ray is blocked by the edge for the first time, and the position is projected on a plane perpendicular to the central axis, The point is that the shape of a figure that is congruent or similar to the plate-like body can be characterized.

The positional deviation of the center of the plate in the in-plane direction can be known from the difference in distance between these reference points and the arrangement of the focused energy lines. When either the focused energy ray or the plate-shaped body is rotated with respect to the other, the relationship between the output and the rotation angle of each point where the focused energy ray is blocked by the plate-shaped body and the arrangement of the focused energy ray are It is possible to obtain the angular deviation from the predetermined angle to be positioned in the in-plane direction of the plate-shaped body.

Based on these data, the position of the plate-shaped body is corrected by the relative movement or rotation of the hand or table holding the plate-shaped body with respect to the sensor unit. Since the number of the plurality of focused energy rays used for the detection line may be any number that can characterize the shape of the plate-like body, the number of emitters and detectors can be small, and the entire apparatus can be simplified.

Further, the emission means for radiating a plurality of focused energy rays in the direction of gradually converging or diverging along the central axis or the detecting means is not installed at a position right above the wafer, so that a clean room is provided. Since it does not disturb the down flow in the above, and dust and minute particles in the atmosphere do not accumulate directly above the wafer, foreign matter does not drop and adhere to the upper surface of the wafer, and high cleanliness and non-contact positioning of the wafer Can be done.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, a guide rail 2 is fixed to a base 1, and a guide block 3 can move on the guide rail 2. Support 4 for guide block 3
Is fixed. A motor bracket 5 is fixed to the base 1, and a pulse motor 7a is fixed to the motor bracket 5.

There is a ball screw nut 6 on the support 4,
A ball screw 8 passed through a ball screw nut 6 is attached to the output shaft of the pulse motor 7a. Therefore, when the pulse motor 7a rotates, the support 4 moves up and down on the guide rail 2 in the Z direction.

A main body 13e of a horizontal articulated robot is attached to the support 4. A robot shaft 13d and a link 13c are provided above the robot body 13e, and the link 13c is further connected to the link 13b and the hand 13a.

In addition, below the robot body 13e, there is provided a driving pulse motor 7c for linearly (radially) expanding and contracting the hand 13a with respect to the robot axis center Or, and the hand 13a is provided for the robot axis. Driving pulse motor 7d for rotating around the center Or (in the circumferential direction)
Is attached. The control device 10 takes charge of control of this horizontal articulated robot.

The wafer 12 transferred from the front and rear devices is placed on the hand 13a. The tip of the hand 13a is bifurcated, and the rotary table 11 having a surface parallel to the surface on which the wafer 12 is placed can be passed between the two. The rotary table 11 is arranged on a housing 18 having a built-in rotary shaft.

The housing 18 is fixed on a bracket 19. A support shaft of the rotary table 11 is rotatably attached to the base 1 via a housing 18 and a bracket 19. A pulse motor 7b for rotating the rotary table is attached to the lower portion of the bracket 19.

The light emitting elements 14a to 14a which emit a plurality of focused energy rays in the direction of gradually converging or diverging along an imaginary central axis which is a normal line at the center of the turntable 11.
14 g and a sensor unit 17 having photodetectors 15 a to 15 g for detecting the radiated light beam 16 (all of which are complicated and therefore represented by 16 d) form a space with the base 1. Housing 1
a (only part of which is shown for simplification). The sensor having the light emitting element 14h and the photodetector 15h will be described later.

The control device 10 includes light emitting elements 14a to 14g.
A driving current is supplied to each of the light emitting elements to emit a light beam. With the wafer 12 not present, the photodetectors 15a-15
Each g receives a light ray. When the light beam is blocked by the wafer 12, the photodetector no longer receives light and changes its output. In this way, the edge portion of the wafer 12 can be detected by the output signal of the photodetector 15.

Encoders 9a to 9d are connected to the output shafts of the pulse motors 7a to 7d and generate signals for detecting the rotation of the output shafts of the respective pulse motors. Photo detector 1
The output signals of 5a to 15g and the output signals of the encoders 9a to 9d are captured by the control device 10. The control device 10 also functions as a driver that supplies drive pulses to the pulse motors 7a to 7d.

Next, the positioning operation will be described. In the positioning, the position of the positioning target such as the wafer may be detected at a certain place, and the position in the final state may not necessarily be detected. Subsequent movement can be known by the amount of movement of the hand or table.

By driving the ball screw 8 by the rotation of the pulse motor 7a, the hand 13a on which the wafer 12 is placed is moved up and down in the Z direction perpendicular to the main surface of the wafer 12,
The position deviation in the in-plane direction from the predetermined position to be positioned can be obtained.

FIG. 2 shows a light beam 16a emitted from the light emitting element.
The relationship between .about.16 g and the wafer 12 is shown. Ray 16a
.About.16 g are radiated in the shape of a cone with the Z axis as the central axis as indicated by the one-dot chain line, and the intersection 16Z is the apex of the cone and is on the Z axis indicated by the two-dot chain line.

The figures connecting the intersections of the light rays 16a to 16g with the plane perpendicular to the Z-axis on the plane are all similar shapes regardless of the height of the plane. In the illustrated case, it is a heptagon, but it can be treated as an equivalent to a circle inscribed with the heptagon.
In an actual device, a shape other than a regular polygon is often used for inserting a hand as will be described later.

First, it is assumed that the position of the wafer 12a in the XY plane is correct and only the position in the Z-axis direction is unknown. Now, it is assumed that the wafer 12a is arranged at the position shown by the dotted line. At this time, since all the light rays 16a to 16g are not blocked by the edge of the wafer 12a, the photodetectors 15a to 15g have all the light rays 16a.
a to 16 g are detected. This means that the wafer 12 has not been detected yet.

Then, the wafer 12 is lowered along the Z axis. At the position indicated by the solid line, all rays 16a to 16g
Are simultaneously blocked by the edge of the wafer 12a. At this time, the photodetectors 15a to 15g do not detect all the light rays 16a to 16g. Therefore, it is judged that the Z direction position of the wafer 12 is detected at this position, and the movement of the wafer 12 is stopped.

Since the light rays 16a to 16g are radiated in the shape of a cone shown by the alternate long and short dash line, the light rays 16a to 16g can be intercepted by the wafer 12 by only slightly moving the wafer 12 in the Z direction, and the position can be rapidly detected. Can be done.

For example, it is easy to position the surfaces of the wafers 12 having different thicknesses at a predetermined height,
Further, even if the diameter of the wafer 12 is different, only the relative position of the light beam and the wafer is changed. By inputting the wafer diameter, the height of the wafer surface can be known from the height at which the wafer blocks the light beam. , The same light beam 16 can be positioned.

In the case of a circular wafer, the light beam may emit at least three light beams whose position can be designated, and therefore the entire apparatus becomes simple. However, the use of a larger number of light beams has the following advantages.

Next, the wafer 12 is moved not only in the Z-axis direction but also in the X-axis direction.
An example will be described in which when there is a deviation in the directions of the axis and the Y-axis, the deviation is detected and corrected if necessary. In this example, the wafer 12 horizontally placed on the hand 13a is inserted between the light emitting elements 14a to 14g and the photodetectors 15a to 15g, and is driven along with the Z axis by the ball screw driving by the pulse motor 7a. To move. The position of the wafer 12 is detected by detecting the position where each light beam contacts the wafer.

When the central axes of the light emitting element group and the photodetector group in the arrangement of the light rays, that is, the Z axis where the intersection 16Z of the light rays emitted in the shape of a cone exists and the central axis of the wafer 12 are eccentric, The position where the edge of the wafer 12 blocks the light beam differs depending on the photodetectors 15a to 15g.

The position where each light beam is blocked is detected,
By calculating the position data by the control device 10, it is possible to detect how much the central axis of the wafer 12 is eccentric from the central axis of the arrangement of the light rays, that is, the position (in-plane deviation) of the wafer 12. it can.

From this calculation result, by moving the wafer 12 in the opposite direction by the amount of eccentricity, the wafer 12 can be accurately centered without contacting the measuring system. Hereinafter, the calculation of the position data performed by the control device 10 will be described in detail.

FIG. 3 shows a state in which the wafer 12 is viewed from above with the direction of arrow A1-A2 in FIG. 1 being horizontal. Consider the projection state on a horizontal plane (XY plane). This figure shows a case where the center Ob of the wafer 12 is eccentric from the central axis Oa of the arrangement of the light rays.

The line connecting the light rays 16a and 16e on the projection plane is on a straight line passing through the central axis Oa, and the line connecting the light rays 16b and 16f is also on a straight line passing through the central axis Oa. Also, light rays 16c and 16g
The line connecting the lines is also on a straight line passing through the central axis Oa.

Further, the light ray 16d is arranged in the direction passing through the central axis Oa at the center of the angle formed by the light ray 16c and the light ray 16e. The light ray 16b and the light ray 16f are directed in the direction of the A1-A2 arrow line, and the light ray 16a, 16c, 16e, 16
g forms an angle of 45 degrees with respect to the direction of the A1-A2 arrow. That is, there is a light ray 16d in the insertion direction of the hand 13a, and each of the light rays 16a to 16g forms an angle of 45 degrees with an adjacent light ray.

When the wafer 12 is moved along the Z axis,
In the illustrated case, the rays of light 16f, 16g, and
16e, 16d, 16a, 16c, 16b are blocked in this order.

When each ray is blocked for the first time, the photodetector 1
The output of 5a to 15g changes, and the height of the wafer can be known. From this height, the length of the outer portion of the wafer 12 of each of the light rays 16a to 16g is known. Let L be the length of the projection of the light rays on the outside of the wafer 12 onto the projection plane.
Let a, Lb, Lc, Ld, Le, Lf, and Lg.

With Oa as the origin, as shown in FIG. 3, the insertion direction of the hand 13a is the Y-axis direction, and the direction perpendicular to the insertion direction of the hand 13a is the X-axis direction. Deviations x and y between the central axis Oa of the arrangement of the light rays and the center Ob of the wafer 12 in the respective axial directions.
Is, for example,

[0043]

[Equation 1]

[0044]

[Equation 2] Can be approximated by Note that the formula changes when rays of light in different directions are used, but the derivation thereof will be obvious to those skilled in the art.

Although FIG. 3 shows the case where the orientation flat of the wafer 12 is not detected by any of the light rays, even when the orientation flat is detected by any of the light rays, which optical axis is the orientation flat, the notch, or the like. Can be determined by comparing the lengths L of the light rays projected onto the main surface of the wafer 12, and the wafer 12 can be determined from the lengths of the light rays at locations where orientation flats, notches, etc. are not detected.
It is possible to calculate the deviations x and y of the center Ob of each axis in each axial direction.

Therefore, the signals of the encoder 9a indicating the heights when the respective light beams 16a to 16g are shielded by the wafer 12 are fetched into the control device 10 of FIG. 1, and the position data of the light emitting elements 14a to 14g which are known in advance are stored. The deviations x and y can be easily obtained by obtaining the lengths La to Lg of the light rays of the respective light-shielded portions from the above formulas and calculating them by the above formulas or the corresponding formulas.

Next, when the hand 13a is moved in the opposite direction by the deviations x and y, the central axis Oa and the center Ob of the wafer 12 are moved.
Match. In this way, the in-plane position of the wafer 12 can be measured and corrected.

Next, the positioning of the orientation flat will be described. First, the central axis Oa is aligned with the center Ob of the wafer 12 by the method described above. When the centering of the wafer 12 is completed, the hand 13a further descends and deposits the wafer 12 on the rotary table 11.

In FIG. 1, the light ray 16h emitted from the light emitting element 14h is received by the photodetector 15h, and the light ray 16h causes the orientation flat portion of the wafer 12 placed on the turntable 11 to move. To detect.

FIG. 4 shows a state viewed from the upper surface of the wafer with the direction of arrow A1-A2 in FIG. 1 being horizontal. The detection of the orientation flat and the operation of directing the orientation flat will be described.

Wafer 12 mounted on rotary table 11
It was assumed that the orientation flat of was in a state of 12 Ta. At this time, the light ray 16h emitted from the light emitting element 14h is blocked at the Oc point on the wafer 12.

When the wafer 12 is rotated in the direction of the arrow by the rotation of the turntable 11, first, when the orientation flat reaches the position of 12 Tb, the light emitting element 14 is moved.
The light beam 16h emitted from h is detected by the photodetector 15h without being blocked by the Oc point on the wafer 12.

Further, when the wafer 12 rotates and the orientation flat reaches the position of 12 Tc, the light beam 16h emitted from the light emitting element 14h is Oc on the wafer 12.
Blocked again at the point.

The angle angle of the orientation flat is detected by the encoder 9b attached to the output shaft of the pulse motor 7b that rotates the rotary table, by detecting the rotation angle until the orientation flat changes from the position of 12Tb to the position of 12Tc. Can be detected, and the rotary table can orient the orientation flat in a designated direction.

Although the case where there is no second flat, notch or the like has been described in this drawing, even if the second flat, notch or the like is present, the orientation flat shape data and the light emitting element 14h which are input to the control device 10 in advance.
The orientation flat can be determined by using the position data of the arrangement of the photodetector 15h and the like.

Further, instead of directing the orientation flat in the designated direction, it is also possible to direct the second flat, notch or the like in the designated direction. The light emitting elements 14a to 14h and the photodetectors 15a to 15h are not provided above the area inside the peripheral edge of the wafer 12, and dust is not collected right above the wafer 12. Also, even if a downflow is formed,
The flow is not disturbed.

Although the deviation was calculated using the length of the blocked light ray portion, the length from the central axis to the wafer edge may be used. The arrangement of light rays can be set in various ways. When it is necessary to position only the lateral position of the strip, it is possible to use two light beams. The light source and the detector may be exchanged.

In the above embodiments, the light beam emitted from the semiconductor laser or the light emitting diode is used as the focused energy beam 16. However, it is possible to use not only rays but also beams having strong directivity, as is clear from the principle. From practical detection, it is preferable to use electromagnetic waves or sound waves in a wider wavelength range including light.

[0059]

As described above, according to the present invention,
There is little risk that foreign matter will fall and adhere to the upper surface of the plate-shaped body, and it is possible to accurately and quickly respond to the position detection of plate-shaped bodies of various shapes and sizes. A positioning device can be obtained.

[Brief description of drawings]

FIG. 1 is a partial perspective view showing a non-contact positioning device for a plate-like body according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a positioning operation in the positioning device shown in FIG.

FIG. 3 is a diagram illustrating another positioning operation performed using the positioning device shown in FIG.

FIG. 4 is a diagram illustrating an operation of positioning an orientation flat performed using the positioning device shown in FIG.

[Explanation of symbols]

 1 Base 2 Guide Rail 3 Guide Block 4 Support 5 Motor Bracket 6 Ball Screw Nut 7 Pulse Motor 8 Ball Screw 9 Encoder 10 Control Equipment 11 Rotary Table 12 Wafer 13a Hand 14a-14h Light Emitting Element 15a-15h Photodetector 16a-16h Ray 17 Sensor unit 18 Housing 19 Bracket

Claims (2)

[Claims] 1. A sensor for detecting a contact of a focused energy ray (16) composed of electromagnetic waves or sound waves having a strong directivity with an edge of a plate to perform non-contact positioning of the plate. A sensor unit having an emission means for gradually converging or diverging the focused energy ray of the emitted energy ray in the direction of divergence and a detecting means for detecting each emitted energy ray; and in a plane substantially perpendicular to the central axis. A means for holding the plate-like body, and one of the sensor unit and the plate-like body is moved or rotated relative to the other so that the edge of the plate-like body is in contact with each of the plurality of focused energy rays. Characterized in that both of the emission means and the detection means, which are located vertically above the plate-shaped body, are installed outside the peripheral edge of the plate-shaped body. Non-contact positioning device for the plate-shaped body to be measured. 2. A plate shape when an edge of the plate body contacts each of the plurality of focused energy rays when either the plate body or the sensor unit is moved or rotated in the direction of the central axis. The non-contact positioning device for a plate-like body according to claim 1, further comprising means for obtaining a position deviation of the plate-like body in the in-plane direction from position data of the body or the sensor unit.