JPH0669323A - Wafer detection device and wafer positioning device - Google Patents

Abstract

PURPOSE:To prevent an erroneous detection caused by reflected light in a photodetection part even when irradiation light radiated from a light-emitting part of a detection means is reflected by a wafer in an irregular reflection manner. CONSTITUTION:In a wafer detection device 1, the position or the number of a plurality of wafers 2 housed inside a carrier 3 is detected optically by light- emitting elements 13a, 13b which radiate light to the wafers 2 and by photodetectors 14a, 14b faced with the light-emitting elements 13a, 13b. The wafer detection device is constituted of a polarization element 15 installed in the incident light path of the photodetectors 14a, 14b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer detecting device and a wafer positioning device.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. 62-133286 is known as a means for detecting the number or position of wafers stored in a wafer carrier. The detecting means is provided with a light emitting portion and a light receiving portion at positions facing each other in the horizontal direction of the wafer accommodated in the wafer carrier, and a transmission type infrared laser capable of transmitting between the wafers is fixed to a fixed portion. The number of wafers or the positions of the wafers is detected by vertically moving the mounting table on which the wafer carrier is mounted and measuring the number or positions of the light beams shielded by the infrared laser light by the wafers. .

Further, as means for positioning an orientation flat provided on the outer periphery of a wafer at a predetermined place, for example, Japanese Patent Laid-Open No. 60-213209 is known. In this positioning device, the light emitting unit and the light receiving unit of the image sensor are fixedly arranged at positions facing each other in the vertical direction of the wafer, and the wafer shields the band-shaped infrared laser light emitted from the light emitting unit. The light-shielding width or the light-transmitting width is detected by the light-receiving unit, and the orientation flat provided on the outer periphery of the wafer is positioned at a predetermined position based on the detection information.

[0004]

However, in the case of detecting the number or positions of wafers by measuring the number or positions of the former infrared laser beams shielded by the wafer, the former infrared laser light is emitted from the light emitting portion. Further, the infrared laser light is reflected on the edge which is the vertical surface of the wafer, and this reflected light is reflected on another wafer housed above or below. Further, since the reflected light becomes multi-level diffuse reflection and is detected by the light receiving portion, there is a problem that the number or position of wafers cannot be accurately detected. Further, if the number of the wafers cannot be detected accurately by the reflected light, when the wafers are loaded into or unloaded from the carrier in which the wafers are stored by the transfer device, the wafers are packed into the pockets of the carriers when the wafers are loaded. There is a problem in that the unprocessed wafer remains unremoved in the carrier and is determined to be empty when the carrier is unloaded. Furthermore, if the position of the wafer cannot be detected accurately, the transfer device may not be able to insert the wafer into the pocket of the carrier because the displacement may occur when the wafer is loaded into or unloaded from the carrier. There is a problem that the wafer is damaged by bringing the wafer into contact with the carrier or the carrier is overturned.

In the latter positioning device,
The light emitting portion and the light receiving portion of the image sensor are fixedly arranged at positions facing each other in the vertical direction of the wafer, and the band-shaped infrared laser light emitted from the light emitting portion is shielded by the wafer, so that the light shielding width or the light transmitting width is reduced. At the time of detection by the light receiving unit, the laser light emitted from the light emitting unit of the infrared laser is reflected at the edge of the outer peripheral edge of the wafer and is reflected on the wall surface in the device to cause irregular reflection. There is a problem that the irregularly reflected light is detected in some parts. Further, in a positioning device that positions an orientation flat provided on the outer periphery of the wafer at a predetermined position by a signal from the infrared laser, it becomes impossible to position at a predetermined position or a position shift occurs due to the influence of the signal of the irregular reflection light. There is a problem. Further, when the wafer is transferred to the processing apparatus that processes the wafer with the positional deviation, the processing apparatus, for example, a plasma etching apparatus, places the wafer in a misaligned state on a mounting table formed in a wafer shape, for example, an electrostatic chuck. Since it is processed, there is a problem that a portion of the electrostatic chuck that does not overlap the wafer is plasma-processed and damaged. Further, if the wafers are transferred with the positional deviations occurring, the orientations of the wafers become uneven, and if the wafers are processed in this state, there is a problem in that the processings vary among the wafers.

An object of the present invention is to provide a wafer detecting device and a wafer positioning device which prevent erroneous detection due to the reflected light in the light receiving portion even if the irradiation light emitted from the light emitting portion of the detecting means is diffusely reflected by the wafer. To do.

[0007]

According to a first aspect of the present invention, a light emitting element for irradiating the wafer with the position or number of a plurality of wafers housed in a carrier, and a light receiving element facing the light emitting element. In the wafer detecting apparatus for optically detecting by the above, a wafer detecting apparatus characterized by a polarizing element provided in an incident optical path of the light receiving element.

According to the second aspect of the present invention, the peripheral edge of the wafer is optically detected by the light emitting element that irradiates the outer peripheral edge of the wafer perpendicularly to the wafer surface, and the light receiving element that opposes the light emitting element. A device for positioning a wafer at a position, characterized by a polarizing element provided in an incident optical path of the light receiving element.

[0009]

According to the present invention, even if the irradiation light emitted from the light emitting portion of the detecting means is diffusely reflected by the wafer, the action of the deflection filter of the light receiving portion can suppress or prevent the detection of the irregular reflection light.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a wafer loading / unloading detection apparatus will be described in detail below with reference to the drawings. As shown in FIGS. 1, 2 and 3, the wafer loading / unloading detection device 1 has a wafer, for example, a semiconductor wafer 2 having a predetermined space within a carrier 3 as shown in FIG.
A plurality of wafers 2 (thickness, for example, about 0.
8 mm (2a) is stored. Further, the carrier 3 is placed on an elevator type mounting table 5, and the mounting table 5 is engaged with a motor, for example, a rotating shaft of an AC servomotor 6 by a coupling belt 7 having a different roller diameter. At the same time, it is connected to an upright ball screw 8 so that its rotation is controlled by the engaging belt 7. Further, above the ball screw 8, the mounting table 5 is screwed, and an elevating mechanism is configured so as to move up and down by the rotation of the ball screw 8. Further, the elevating mechanism is configured to be controlled by the position detection information of the wafer 2.

An arm 10 for adsorbing the wafer 2 is provided near the carrier 3, for example, at a position facing each other, and the arm 10 has a vacuum hole 10a connected to a suction pipe (not shown) for vacuuming the wafer 2.
Are formed. Further, the arm 10 is configured to carry in or carry out the wafer 2 to / from the carrier 3 by an arm loading / unloading mechanism 11.
Is installed on the first fixed base 12. Further, the arm loading / unloading mechanism 11 transmits the rotation to a roller provided on the fixed base 12 and coupled to the rotation shaft of the motor by a belt, and this rotation further moves the arm 10 in the arrow direction. Is provided.

A wafer position detecting mechanism for detecting the position of the wafer 2 is provided between the carriers 3 on the traveling path of the arm 10. The wafer position detecting mechanism is an optical sensor, for example, a transmissive infrared sensor. While using the wafer 2 housed in the carrier 3, two systems of light emitting parts 13a and 13b, each having a light emitting element built therein, are arranged on the side of the arm 10, for example.
a and 13b are fixedly installed on the fixed base 12. On the other hand, a light receiving unit 14 having a built-in two-system light receiving element paired with the light emitting units 13a and 13b, is fixedly installed on a second fixed base 16 facing the fixed base 12 through the wafer 2. The light receiving section 14 includes the light emitting section 13
Infrared lasers emitted from a and 13b, for example, photodetection openings 14a and 14 for receiving semiconductor laser light having a wavelength of 300 nm to 10 μm on the light receiving element, respectively.
b, for example, a height of 0.5 mm to 3 mm and a width of 2 mm to 10 m
m has been drilled. Further, this light detection opening 14
A polarizing element, for example, a sheet-like polarizing plate having a structure in which a polarizing film is sandwiched by a transparent plastic sheet, or a polarizing film is glued between two glass plates so as to cover the entire surfaces of the openings 14a and 14b. A polarizing filter (polarizer: product name) 15 adhered to is fixedly attached.

Further, as shown in FIG.
A light emitting element 20 is fixedly installed inside 3a, and an operation signal for controlling the operation of the light emitting element 20 is connected to the drive circuit 25 in the light emitting element 20. Further, the laser light 23 emitted from the light emitting element 20 is projected from the light projecting opening 24 to the light receiving portion 14 through the light projecting lens 21 for condensing the laser light 23. It is configured to be illuminated. A polarization filter 15 is fixedly attached to the light receiving portion 14 so as to cover the light detection opening 14a.
To receive the laser light 23. Further, the received laser beam 23 is received by the light receiving lens 2
The photoelectric signal output from the light receiving element 27 is connected to a signal amplifier circuit 28 for amplifying the photoelectric signal. There is. Further, the photoelectric signal amplified by the signal amplifier circuit 28 is connected to a detection circuit 29 for determining and detecting the position by the photoelectric signal depending on the presence or absence of the wafer 2. The wafer loading / unloading detection device is configured as described above.

Next, the operation of detecting the wafer 2 of the first embodiment will be described. For example, when detecting the position of the wafer 2 in the carrier 3, the mounting table 5 is moved up and down, and at the same time, the position of the wafer 2 is detected by a two-system infrared sensor composed of the light emitting units 13a and 13b and the light receiving units 14a and 14b. The horizontal state is detected and stored in a semiconductor memory or the like (not shown).
That is, the mounting table 5 is moved up and down in synchronism with the rotation of the motor 6 of the elevating mechanism, and the position where the wafer 2 first blocks the optical path of the laser light 23 and the position where the wafer 2 is opened next are measured. Can be detected. The position of the wafer 2 is detected by temporarily storing this position in a semiconductor memory and calculating the distance between the two positions as a constant.

However, the light emitting portions 13a and 13b are
As shown in FIG. 4A, the laser light 23 emitted from the laser light 23 emitted from the light emission opening 24 of the light emitting portion 13a travels along the optical path with a spread of the beam angle θ1. . Further, the wafer 2 is also moved up and down in synchronization with the lifting mechanism. As shown in FIG. 4A, the peripheral portion of the wafer 2 has a convex shape having a curved surface with a radius R, and the laser light 23 is reflected on the convex peripheral portion.
For example, the light is reflected by 30a and 30b, and travels as reflected light 32 and 33 having angles θ2 and θ3. As shown in FIG. 4B, the reflected lights 32 and 33 are reflected on the wafer 2X positioned above the wafer 2 that has caused the reflection, and the reflected lights 32 and 33 are repeatedly reflected on the wafer 2. While advancing, the light detection opening 14a of the light receiving unit 14
The light is incident on the deflection filter 15 that is fixedly attached to and transmits only the vertically transmitted light. Further, the deflection filter 1
The irregular reflection lights 32 and 33 entering the light beam 5 at the angle θ3 are suppressed or blocked by the deflecting action of the deflection filter 15.

As described above, the light detection opening portion 14 of the light receiving portion 14 is
When the deflection filter 15 is fixedly attached to a, the output waveform of the light receiving element 27 is as shown in FIG. 5A, the position of the wafer 2 is detected by the signal amplification circuit 28.
The wafer detection waveform 35 output from the light receiving element 27
Is transmitted, for example, 36a is set when the nth optical path is blocked,
The position of the wafer 2 is sequentially detected when the elevating mechanism is lowered or raised like 36b when the light path of the n + 1th sheet is blocked and 36c when the light path of the n + 2nd sheet is blocked. However, when the deflection filter 15 is not fixed to the light detection opening 14a of the light receiving unit 14, the reflected light passes through the light receiving element 27 and the light receiving lens 26 as shown in FIG. 5B. When the light path is blocked by the wafer 2, a glitch 37 is generated, and an edge 38 is generated even when the light path is opened. Further, the wafer detection waveform 35 is transmitted to the signal amplification circuit 28 and is amplified, and the position is detected by the detection circuit 29.

According to the above embodiment, the following effects can be obtained. (1) Since the optical path of the infrared laser light is blocked by the wafer 2, the infrared laser light emitted from the light emitting portions 13a and 13b is an edge that is a vertical surface of the wafer 2 when detecting the number or positions of the wafers. The reflected light is reflected on the wafer 2 housed above or below, and the reflected light becomes a multi-stage diffuse reflection and enters the light receiving portion 14 of the infrared laser.
5, it is possible to prevent or suppress light entering, and it is possible to accurately detect the number or position of the wafers 2 in the carrier 3. (2) Further, since the number of the wafers 2 can be accurately detected by the reflected light, when the wafers 2 are loaded into or unloaded from the carrier 3 in which the wafers 2 are loaded by the transfer device 11, the carriers are accurately loaded during loading. The wafer 2 can be inserted into the pocket 4 of the carrier 3 and it can be prevented that the wafer 2 of the carrier is empty while the unprocessed wafer 2 remains in the carrier 3 at the time of unloading. (3) Furthermore, since the position of the wafer 2 can be accurately detected, the transfer device 11 transfers the wafer 2 to the carrier 3
When it is carried in or out of the carrier, it is possible to accurately insert it into the pocket 4 of the carrier 3 because it prevents the displacement, and it is possible to safely contact the wafer 2 with the carrier 3 without damaging the wafer 2 or tipping the carrier 3. You can carry in and out. (4) In addition, when the horizontal state of the wafer 2 is detected by the light receiving portions 14a and 14b, which have two light receiving elements paired with the light emitting portions 13a and 13b, the influence of the reflected light is eliminated. The horizontal state of the wafer 2 can be accurately detected, and the wafer 2 is obliquely stored by the transfer device 11.
Since it is possible to prevent the carrying-in / carrying-out of the wafer 2 and to prevent the wafer 2 from being damaged, the reliability of carrying-in / carrying-out by the transfer device 11 can be improved.

Next, the second applied to the wafer positioning device.
The embodiment will be described, but the same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. As shown in FIG. 6, the carrier 3 for accommodating the wafer 2 is arranged on a mounting table (not shown) that moves up and down.
A transport device 40 is disposed in front of the. The transfer device 40 has an opening 41, and an arm 10 that holds the wafer 2 by suction so that the center of the wafer 2 is located at the opening 41, and an arm 1 such as a stepping motor.
It is composed of a drive unit 42 for moving 0 in the Y direction. Then, the tip of the arm 10 is inserted into the carrier 3 by the driving unit 42, and then the carrier 3 is slightly lowered by an elevating mechanism (not shown) to place the wafer 2 on the arm 10 and a vacuum chuck (not shown). The wafer 2 is pulled out from the carrier 3 in a sucked and held state. A wafer holding mechanism 43 is arranged in the movement path of the arm 10. The wafer holding mechanism 43 is formed in a cylindrical shape, and a chuck base 44 for sucking and holding the wafer 2 by a vacuum chuck (not shown) is provided on the upper surface thereof. The chuck base 44 is provided with a drive unit, for example, a rotation drive unit 45 composed of a stepping motor or the like, on the lower side of the chuck base 44, and is configured to be rotatable while holding the wafer 2 by suction. Has been done.

Further, a detection mechanism 47 for detecting the position of the end portion of the wafer 2, which is adsorbed and held on the arm 10, is arranged on the substrate 46, and the detection mechanism 47 has an image sensor. A semiconductor sensor having a wavelength of, for example, about 780 nm is provided at a fixed place, for example, so as to face each other vertically, and a light emitting unit 50 is disposed below the one and a light receiving unit 51 is disposed above the other. The detection mechanism 47 is connected via an arm 49 to a drive unit 48 that moves the detection mechanism 47 in the X direction by, for example, a stepping motor or the like. In addition, as shown in FIG. 7, a belt-shaped laser beam 5 emitted from the light emitting unit 50.
2 is projected toward the light receiving portion 51 and proceeds, and the light detection opening portion 53 of the light receiving portion 51 has a height, for example, 0.5 mm to 3 mm.
The laser light 52 is configured to be received by the light receiving unit 51 via the polarization filter 15 attached so as to cover a width of, for example, 2 mm to 10 mm in mm, and further,
The chuck base 44 is rotated by the rotation drive unit 45, and the wafer 2 is rotated in synchronization with the rotation, so that the wafer 2 shields the laser beam 52 of the band shape, for example, 0 to 400 mm. The width or the translucent width is measured by the light receiving unit 51, the position of the orientation flat 2a of the wafer 2 is detected, and the output signal output from the light receiving unit 51 at the center position of the wafer 2 is a detection circuit (not shown). And the position of the orientation flat 2a of the wafer 2 is detected by this detection circuit. Further, the detection signal obtained by detecting the position of the orientation flat by the detection circuit is output from the rotation drive unit 4 of the chuck base 44.
5 is transmitted to the rotation drive unit 45 according to the detection signal.
Is configured to perform the angular positioning control. The wafer positioning device is configured as described above.

In the above-mentioned wafer positioning apparatus, the operation and effect of detecting the wafer 2 will be described below. Figure 8
As shown in FIG. 5, the strip-shaped laser light 52 emitted from the light emitting section 50 is projected toward the light receiving section 51, travels, and is shielded by the wafer 2, for example, at a reflection position 5.
Part of the laser light 52 is reflected at the position of 3,
In the case of processing in a clean room where high cleanliness is required, as shown in FIG. 9 showing particles and particle size depending on the atmosphere, the side wall 54 of the device reflects the direction toward the substrate 46 and is made of stainless steel. When the apparatus is coated, the dust 60 of particles such as the coating floats in the clean room, which affects the yield of integrated circuits on the wafer 2. In view of the above, the apparatus is not coated. In general, the reflectance is high.) While repeating the reflection, the light travels toward the light receiving portion 51. The reflected light 55 that has traveled enters the deflection filter 15 and is suppressed or blocked by the deflection action of the deflection filter 15. Further, the belt-shaped laser light 52 which is not shielded by the wafer 2 is projected onto the light receiving portion 51 through the deflection filter 15 which transmits only the vertically incident light, and the light transmission width is detected.

The chuck base 44 of the wafer 2 is rotated by a rotating mechanism, and the measurement signal output from the light receiving section 51 at this time is an output signal as shown in FIG. 61 is output from the light receiving unit 51. The peak point 62, which is the maximum value of the output voltage of the output signal 61, is the detection position of the orientation flat 2a of the wafer 2. Further, by detecting the peak point 62, the chuck base 44 is rotated by a rotation mechanism to move the orientation flat 2a to a predetermined position by a rotation angle and perform positioning. However, when the deflection filter 15 is not attached to the light receiving section 51, as shown in FIG.
The reflected light 55 enters the light receiving portion 51, and the output signal 6
Edges 63a and 63b are generated at 1. The edges 63a and 63b are aligned with the orientation flat 2a.
Since the voltage is higher than the peak value 62, the edges 63a and 63b are erroneously detected as orientation flat positions, and the chuck base 44 cannot be accurately positioned.

In the positioning device described in detail above, the light emitting section 50 and the light receiving section 51 of the infrared sensor are fixedly arranged at positions facing each other in the vertical direction of the wafer 2, and a band-shaped infrared laser emitting from the light emitting section 50. Light 52
When the light-shielding width or the light-transmitting width is detected by the light-receiving unit 51 by shielding the wafer 2 from light, the laser light 52 emitted from the light-emitting unit 50 of the infrared laser is reflected on the edge of the outer peripheral edge of the wafer 2. Even so, since the deflection filter 15 blocks or suppresses the reflected light 55, the position of the orientation flat 2a of the wafer 2 can be accurately detected. Further, the wafer 2
Since the position of the orientation flat 2a can be accurately detected by the detection circuit, the orientation flat 2a provided on the outer periphery of the wafer 2 is moved to a predetermined position based on the detection signal output from the detection circuit. The movement angle of the rotating mechanism of the chuck base 44 can be accurately controlled. Further, since the movement angle of the rotating mechanism of the chuck base 44 can be accurately controlled, the next stage processing apparatus, for example, a plasma etching apparatus, is misaligned to a mounting table formed in a wafer shape, for example, an electrostatic chuck. In this state, the wafer 2 can be accurately placed on the electrostatic chuck, which is a placing table for the wafer 2.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention. It is needless to say that the deflection filter 15 may be fixed and fixed to the inside of the light detection opening 14a of the light receiving unit 14, and the deflection filter 15 may be attached to the light emitting unit side. Needless to say. In the above embodiments, the polarizing plate 15 having a structure in which the polarizing film is sandwiched by the transparent plastic sheets or the polarizing filter 15 in which the polarizing film is bonded to the middle of two glass plates with an adhesive is described. Alternatively, any deflection element may be used as long as it suppresses it. Furthermore, when the above-mentioned detection device is attached to a semiconductor manufacturing device, it is naturally applicable to a plasma processing device such as an etching device, a plasma CVD device, an LCD device, an ECR device, or a cleaning device, a diffusion device, a heat treatment, etc. is there. Further, the invention is not limited to the semiconductor manufacturing apparatus, but can be applied to any apparatus as long as it can detect a wafer by an optical sensor.

[0024]

As described above, according to the present invention, even if the irradiation light emitted from the light emitting portion of the detecting means is reflected by the wafer, the detection of irregularly reflected light in the deflection filter of the light receiving portion can be suppressed or prevented. Therefore, there is a remarkable effect that the number or position of wafers can be accurately detected.

[0025]

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a wafer loading / unloading detection device according to a first embodiment of the present invention.

FIG. 2 is a partial schematic cross-sectional view of a carrier of the wafer loading / unloading detection device of FIG.

FIG. 3 is a schematic cross-sectional view for explaining the wafer detection operation of FIG.

FIG. 4A is a partial cross-sectional view for explaining reflected light of the infrared sensor light of FIG. FIG. 2B is a partial cross-sectional view for explaining reflected light transmitted through the light receiving portion of the infrared sensor of FIG. 1.

5 (a) is a waveform diagram showing an output waveform of the infrared sensor of FIG. 1 on a time axis. (B) It is a waveform diagram which shows the output waveform of the infrared sensor of FIG. 1 on a time axis.

FIG. 6 is a schematic perspective view illustrating another embodiment of FIG.

FIG. 7 is a partial schematic cross-sectional view for explaining detection of the wafer in FIG.

FIG. 8 is a partial schematic cross-sectional view for explaining reflected light of the infrared sensor light of FIG.

FIG. 9 is an explanatory view showing general particles existing in the atmosphere and their diameters in the prior art.

10 (a) is a waveform diagram showing an output waveform of the infrared sensor of FIG. 6 on a time axis. 7B is a waveform diagram showing the output waveform of the infrared sensor of FIG. 6 on the time axis.

[Explanation of sign]

 1 wafer loading / unloading detection device 2 wafer 2a orientation flat 3 carrier 13a, 13b light emitting part 14 light receiving part 14a, 14b light detection opening 15 deflection filter 20 light emitting element 23 laser light 24 light projecting opening 27 light receiving element 32, 33 reflected light

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01L 31/12 G 7210-4M

Claims (2)

[Claims] 1. A light-emitting element for irradiating the wafer with the position or the number of a plurality of wafers stored in a carrier, and a wafer detection device for optically detecting the light-receiving element facing the light-emitting element. A wafer detecting device characterized by a polarizing element provided in an incident optical path of the light receiving element. 2. A light emitting element that irradiates the outer peripheral edge of the wafer perpendicularly to the wafer surface, and a light receiving element facing the light emitting element optically detects the peripheral edge of the wafer to position the wafer at a predetermined position. In the above apparatus, a wafer positioning device characterized by a polarizing element provided in an incident light path of the light receiving element.