JP2003197705A - Apparatus for attaching/detaching cassette cover - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent damage to a wafer when it is popped out from a cassette due to a positional shift by detecting it in an apparatus for attaching/detaching a cover of the cassette for accommodating the wafer. <P>SOLUTION: The apparatus for attaching/detaching the cassette cover comprises a shielding door 30, capable of opening/closing an opening 11 faced by the cover 3 of the cassette 1 for accommodating the wafer, and capable of holding the cover, and driving mechanisms 40, 80 for moving the shielding door 30, while it holds the cover 3, forward/backward and upward/downward to attach/detach the cover 3 and the shielding door 30. A reflection type optical sensor 90 for projecting light in the direction nearly orthogonal to the main surface of the wafer is provided in the region of the opening 11. Thus, even if the wafer is transparent, the positional shift thereof can surely be detected so that the damage, etc., thereto can be prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cassette lid attaching / detaching device for attaching / detaching a lid of a cassette for accommodating semiconductor wafers in a hermetically sealed state, and more particularly to a cassette having a function of detecting the state of the accommodated wafers. The present invention relates to a lid attaching / detaching device.

[0002]

2. Description of the Related Art As a cassette for carrying a plurality of semiconductor wafers in a sealed state, a FOUP (Front
Open Unified Pod) cassettes are known. As shown in FIG. 7, the cassette 1 is formed of a case body 2 and a lid 3 that can seal the opening 2a on the front surface. The lid 3 is provided with a lock mechanism 3a for locking the case body 2 in a sealed state, and an elastically deformable attachment inside the lid 3 for pressing and fixing the wafer W in the sealed state. A bias arm 4 is provided.

In order to take out the wafer W toward the internal space, such a cassette 1 is arranged adjacent to a partition for defining an internal space for manufacturing a semiconductor, a shield door detachably attached to the partition is opened. There is known a cassette lid attaching / detaching device for attaching / detaching the lid 3 together with the shielding door. Examples of this type of cassette lid attaching / detaching device include, for example, JP-A-11-145244 and JP-A-11-2.
Those described in Japanese Patent No. 14483 and the like are known.
In the devices disclosed in these publications, a reflection type optical sensor capable of detecting the outer peripheral edge of the housed wafer W is provided. The reflective optical sensor detects whether or not a predetermined number of wafers W are stored in the cassette 1, that is, the presence or absence of the wafers W.

[0004]

By the way, when the lid 3 is retracted and opened by the above apparatus, the wafer W may be pulled out in a state of being in close contact with the biasing arm 4.
Therefore, if the transfer operation of the transfer robot or the raising / lowering operation of the shield door is performed while the wafer W is ejected from the cassette 1, the wafer W may be damaged.

Further, since an opaque silicon wafer is generally used as the wafer W, a transmissive optical sensor can be used as the optical sensor, but in most cases when a transparent quartz wafer is used. Since light passes through the quartz wafer, it is difficult to detect the quartz wafer with a transmissive optical sensor.

The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to prevent misalignment such as popping-out of wafers stored in a cassette.
It is an object of the present invention to provide a cassette lid attaching / detaching device that can detect wafers with high precision with a simple structure and prevent damage to the wafer.

[0007]

SUMMARY OF THE INVENTION A cassette lid attaching / detaching device according to the present invention includes a shield door capable of opening and closing an opening facing a lid of a cassette for storing wafers and holding the lid, and a lid with the lid held. And a cassette lid attaching / detaching device including a drive mechanism for moving the shielding door forward / backward and lifting the shielding door in order to attach / detach the shielding door, in the area of the opening.
It is characterized in that a reflection type optical sensor for projecting light in a direction substantially orthogonal to the main surface of the wafer is provided.

According to this structure, in the process of retracting the cover door in the state where the drive mechanism holds the cover and separating the cover and the cover door, the wafers housed in the cassette adhere to the cover, for example. When pulled out, the reflective optical sensor detects the wafer that has jumped out from the predetermined storage position. In particular, since it is detected by the reflection type optical sensor, whether the wafer is an opaque body or a transparent body can be surely detected if the wafer is on the optical path. Further, since light is projected by the reflection type optical sensor not on the outer peripheral edge of the wafer but on the flat main surface, more accurate detection can be performed. In this way, by detecting the displacement of the wafer, it is possible to prevent the transfer robot and other moving bodies from colliding with the jumped-out wafer, and prevent the wafer from being damaged.

In the above structure, the reflection type optical sensor is
A configuration including an upper side optical sensor arranged on the upper edge side of the opening and a lower side optical sensor arranged on the lower edge side of the opening can be adopted. According to this configuration, the upper light sensor and the lower light sensor respectively perform sensing, so that more accurate detection can be performed. In particular, among the plurality of wafers stored in the cassette, the upper half of the wafer can be detected mainly by the upper photosensor, and the lower half of the wafer can be mainly detected by the lower photosensor. Therefore, the detection distance is also approximately half the area, which enables more accurate and stable detection.

In the above structure, it is possible to adopt a structure in which the upper optical sensor and the lower optical sensor are arranged at positions where their optical axes are separated from each other in the direction along the main surface of the wafer. According to this configuration, since the optical axis of the upper optical sensor and the optical axis of the lower optical sensor are displaced from each other, mutual interference is prevented and highly accurate detection can be performed. In particular, it is suitable when an optical sensor having no mutual interference preventing function is used.

In the above structure, the reflection type optical sensor is
It is possible to adopt a configuration in which it is covered with a conductive resin cover that allows transmission of light. With this configuration, it is possible to prevent the cleaning agent, dust, or the like from directly adhering to the optical sensor when the device is cleaned, and to secure a stable detection function.

In the above structure, the detection timing of the reflection type optical sensor can be set before the lid and the shield door are moved up and down by the drive mechanism. According to this configuration, since the detection operation is performed before the lid and the shield door start the ascending / descending operation, it is possible to prevent the light emitted from the optical sensor from being reflected by the outer edge portion of the lid and the like. False detection can be prevented.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 5 show an embodiment of a cassette lid attaching / detaching device according to the present invention. FIG. 1 is a perspective external view, FIG. 2 is a vertical sectional view, and FIG. 3 is a vertical sectional view showing the vicinity of an opening. 4 is a rear view seen from the internal space side for manufacturing a semiconductor, and FIG. 5 is a cross-sectional view showing the vicinity of the opening.

This device, as shown in FIGS. 1 and 2,
A partition 10 that forms a part of a partition S that separates an internal space for manufacturing a semiconductor from an external space, a substantially rectangular opening 11 that is formed in the partition 10 for loading and unloading the wafer W, and a table 20 located in the external space. A mounting plate 21 on which the cassette 1 is mounted, which is reciprocally supported on the table 20, a drive mechanism 22 for reciprocating the mounting plate 21 in the horizontal direction H, a shielding door 30 capable of opening and closing the opening 11, a shielding door An advancing / retreating drive mechanism 4 for advancing / retreating 30 in the horizontal direction H
0, a mapping sensor 50 for scanning the vicinity of the opening 2a of the cassette 1 in the vertical direction V to detect the presence or absence of the wafer W and its driving mechanism 60, an advance / retreat driving mechanism 40, and a driving mechanism 60.
And an elevating and lowering member 70 for holding the elevating and lowering member 70, an elevating and lowering drive mechanism 80 for elevating and lowering the elevating and lowering member 70 in the vertical direction V, a reflection type optical sensor 90 (91, 92) arranged at the edge of the opening 11, and the like.

The loading plate 21 positions the loaded cassette 1 and conveys it in the horizontal direction H, and the lid 3 opens the opening 1.
The cassette 1 is brought into close contact with the front surface of the partition wall portion 10 so as to face 1 (shielding door 30). Drive mechanism 22
As shown in FIG. 2, the lead screw 2 that is screwed into the servomotor 22a and the female screw portion 21a of the mounting plate 21 is used.
2b, a guide shaft 22c inserted into the guide hole 21b of the mounting plate 21 and the like.

The shield door 30 is for opening and closing the opening 11, and is provided with a holding mechanism (not shown) for holding the lid 3. As shown in FIG. 2, the advancing / retreating drive mechanism 40 includes a support member 41 that supports the shield door 30, a servo motor 42, a lead screw 43 that is screwed into a female screw portion of the support member 41, and the support member 41 in the horizontal direction H. It is formed by a guide rail 44 for guiding.

The mapping sensor 50 is a transmissive optical sensor and has a light emitting element and a light receiving element which are arranged so as to sandwich the wafer W in the horizontal direction. Drive mechanism 60
2, the holding arm 61 that holds the mapping sensor 50, the servomotor 62, and the holding arm 61
It is formed by a lead screw 63 that is screwed into the female screw portion of No. 3, a guide rail 64 that guides the holding arm 61 in the horizontal direction H, and the like.

The elevating member 70 integrally holds the shield door 30, the drive mechanism 40, the mapping sensor 50, the drive mechanism 60 and the like, and is moved up and down in the vertical direction V. As shown in FIG. 2, the elevating / lowering drive mechanism 80 includes a servo motor 81, a lead screw 82 screwed into a female screw portion of the elevating / lowering member 70, and a guide shaft 83 inserted into a guide hole of the elevating / lowering member 70.
And the like.

As shown in FIGS. 1 to 3, the reflection type optical sensor 90 has an upper side optical sensor 91 arranged on the upper edge 11a side of the opening 11 and a lower side edge 11b side of the opening 11. And the lower side optical sensor 92.
As shown in FIG. 3, the upper optical sensor 91 and the lower optical sensor 92 include light emitting elements 91a and 92a that emit detection light,
The light receiving elements 91b and 92b for receiving the reflected light reflected by the main surface WS of the wafer W are integrally formed as a unit, respectively, and the main parts of the wafer W arranged vertically in the cassette 1 are arranged. The detection light is projected in a direction substantially orthogonal to the surface WS. As described above, since the portion for projecting the detection light is not the outer peripheral edge of the wafer W but the main surface WS having a flat and wide area, a wide reflecting surface is secured. Therefore, erroneous detection is prevented and stable detection can be performed.

As shown in FIGS. 4 and 5, the upper photosensor 91 and the lower photosensor 92 are located at the center C of the wafer W.
It is arranged at a position separated from the central vertical plane VS passing through (the center of the opening 11) in the horizontal direction by an equal distance D. That is, the upper optical sensor 91 and the lower optical sensor 92 are arranged such that their optical axes are separated from each other by a distance 2D in the direction along the main surface WS of the wafer W. By arranging in such a separated position, the upper side optical sensor 91
Further, it is possible to prevent mutual interference between the lower optical sensor 92 and the lower optical sensor 92, which enables highly accurate detection.

Further, as shown in FIG. 4, the upper side optical sensor 9
1, the wafer W mainly in the upper region U above the central horizontal plane HS is detected, and the lower optical sensor 92 mainly detects the wafer W in the lower region L below the central horizontal plane HS.
Can be detected. Therefore, since it is sufficient to perform sensing in almost half the area, more accurate and stable detection can be performed. In the above structure, the upper photosensor 91 can detect not only the upper half region but also the lower half region as long as the capability of the sensor allows, while the lower photosensor 92 can detect it. It is possible to detect not only the lower half region but also the upper half region.

Here, regarding the distance between the upper photosensor 91 and the lower photosensor 92, as the value of the distance D becomes smaller, the point at which the wafer W can be detected is closer to the center of the wafer W, and the front side in the take-out direction. That is, even if the protrusion amount of the wafer W is small, the positional deviation can be detected. On the other hand, if even a slight positional deviation (protrusion) that does not cause damage to the wafer W is detected, it is necessary to stop the operation of the apparatus each time and perform a confirmation work, which lowers the throughput. Therefore, when the distance D is set, a value is set within a range in which mutual interference between the upper optical sensor 91 and the lower optical sensor 92 does not occur, and a position deviation (protrusion) that does not hinder is detected. Is preferred.

As shown in FIGS. 1 and 3, the upper half of the partition 10 including the table 20 and the opening 11 is covered with a resin cover 100 formed by molding a resin material. The resin cover 100 is a conductive polymer alloy (multi-component polymer) type resin that does not deteriorate even when cleaned (wipe) with a cleaning agent such as isopropyl alcohol and semipermanently secures antistatic performance. It is formed of a material, for example, an ABS resin (alkylbenzene sulfonate resin) excellent in recyclability, colorability, and impact resistance. Here, in order to prevent charging, the electric resistance value is in the range of 1010Ω to 1013Ω, and more preferably 1
A conductive material having a resistance value of 05Ω or less is preferable. still,
From the viewpoint of fire prevention, a flame-retardant resin material is more preferably used.

The resin cover 100, as shown in FIG.
A dent portion 110 having a step on both sides sandwiching the mounting plate 21
It is formed to have. Therefore, cassette 1
When automatically transporting and placing on the mounting plate 21,
The hand of the transfer robot that supports the lower surface of the cassette 1
The cassette 1 is inserted into the recess 110 to mount the mounting plate 2
By placing the cassette 1 on the cassette 1 and then descending and retracting it a little, the cassette 1 can be easily mounted.

Further, the resin cover 100 has a structure shown in FIG.
As shown in FIGS. 3 and 4, the reflective optical sensor 90 (9
1, 92) are formed integrally with transparent windows 101 and 102 which allow the transmission of light while covering the area of 1, 92). The transparent windows 101 and 102 are made of a conductive acrylic resin or the like. Therefore, it is possible to prevent the cleaning agent, dust, or the like from directly adhering to the optical sensor 90 (91, 92), and to secure a stable detection function.

Next, the operation of the above device will be described.
The above-described device includes a control unit (microcomputer) that controls various controls, a sensor that detects switching timing of various operations, and sends the detection information to the control unit, and various operations are issued from the control unit. It is performed based on the control signal. First, a cassette 1 containing a plurality of wafers W
However, when mounted and positioned on the mounting plate 21, the drive mechanism 22 operates to bring the cassette 1 close to the partition wall portion 10 and bring them into close contact with each other. At this time, as shown in FIG. 2, the lid 3 is in a state of facing the shielding door 30 (opening 11).

Subsequently, the holding mechanism built in the shielding door 30 operates to release and hold the lock mechanism 3a of the lid 3. After that, the advancing / retreating drive mechanism 40 is activated, and the lid 3
The shield door 30 holding the is moved (retracted) to the rear B as shown in FIG. By this retreating operation, the lid 3 is detached from the cassette body 2 to open the cassette 1, and the shield door 30 is detached from the opening 11, so that the inside of the cassette 1 communicates with the internal space for manufacturing a semiconductor. It will be in the state of doing.

In the process of this backward movement, the lid 3
As shown in FIG. 3, while being in close contact with the urging arm 4 of
The wafer W may be pulled out. In this way, when the wafer W jumps out of the predetermined storage position and is displaced, the upper side optical sensor 91 and the lower side optical sensor 92.
The wafer W that pops out is detected. Based on this detection signal, the subsequent operation is stopped, and a notification signal (blinking of a notification lamp, notification buzzer, etc.) for notifying the operator of this is issued. As a result, the operator can perform the work of returning the wafer W, which has been displaced, to a predetermined position. By this inspection work, it is possible to prevent damage or the like of the wafer W that may occur when the operation is continued with the wafer W popping out.

Here, the reflection type optical sensor 90 (91, 9)
As shown in FIG. 3, the detection timing of 2) is set before the shield door 30 finishes the backward movement operation and performs the ascending / descending operation (here, the descending operation). With the above detection timing, erroneous detection can be prevented, and highly accurate detection can be performed. If detection is performed after the lifting drive mechanism 80 is activated and the lid 3 and the shielding door 30 start to descend, for example, a part of the detection light projected from the upper side optical sensor 91 will be an outer edge of the lid 3. Reflected by the part 3b,
When the reflected light is received, it is erroneously detected that the wafer W exists even though the wafer W does not jump out. If the processing operation is stopped at each false detection, the throughput (productivity) is lowered. To deal with this, by setting the above detection timing, it is possible to prevent erroneous detection and improve throughput.

When the reflection type optical sensor 90 (91, 92) does not detect the protrusion of the wafer W, or when the rework is performed after the protrusion, the driving mechanism 60 causes the mapping sensor 50 to move to the wafer W. Bring it closer and set it to a position where it can be sensed.

Subsequently, the drive mechanism 80 is operated to move (lower) the elevating member 70 downward, whereby the lid 3 and the shielding door 30 are retracted from the opening 11, and the mapping sensor 50 scans downward. Then, the presence or absence of the wafer W is detected. After that, a transfer robot (for example, an articulated robot) installed in the internal space for manufacturing a semiconductor approaches the opening 11, takes out the wafer W, and transfers it to various processing steps. On the other hand, the raising / lowering drive mechanism 80, the drive mechanism 60, and the advancing / retreating drive mechanism 40 respectively operate in the opposite directions, so that the shield door 30 is attached to the opening 11 to close the opening 11, and the lid 3 is attached to the cassette body 2. Attached to seal cassette 1.

As described above, the reflection type optical sensor 90 is provided to detect the positional deviation such as whether or not the wafer W accommodated in the cassette 1 is popped out from the predetermined accommodation position. Even a wafer can be reliably detected, damage to the expensive wafer W can be prevented, and the yield is improved as a whole, and the throughput is improved.

FIG. 6 shows another embodiment of the device according to the present invention. In this embodiment, as shown in FIG. 6, a reflection type optical sensor 90 is arranged on the central vertical surface VS. Here, as the reflective optical sensor 90, the upper optical sensor 91 may be arranged on the upper edge 11a side of the opening 11 and the lower optical sensor 92 may be arranged on the lower edge 11b side. In this case, in order to prevent mutual interference between the two, it is preferable to use an optical sensor with a mutual interference preventing function. If the reflective optical sensor 90 has a high sensing ability (a wide sensing range), the reflective optical sensor 9 is provided on one of the upper edge 11a side and the lower edge 11b side.
One 0 may be provided.

By arranging the reflection type optical sensor 90 on the central vertical surface VS as described above, even if the wafer W slightly jumps out and a positional deviation occurs, detection can be performed.
Therefore, it is suitable in the case where the operation of the transfer robot or the mapping sensor 50 is hindered even if the protruding amount of the wafer W is small.

In the above embodiment, the reflective optical sensor 9 is provided on the upper edge 11a side and the lower edge 11b side of the opening 11.
0 (91, 92) is provided for each one, but the present invention is not limited to this, and a plurality of reflective optical sensors 90 are arranged on the upper edge 11a side and the lower edge 11b side, respectively. You may.

[0036]

As described above, according to the cassette lid attaching / detaching device of the present invention, the main surface of the wafer is provided in the area of the opening portion where the lid of the cassette for storing the wafer is faced and is closed by the shielding door. By providing the reflection-type optical sensor that projects light in a substantially orthogonal direction, it is possible to detect a wafer that has popped out and has been displaced. As a result, it is possible to prevent the transfer robot and other moving bodies from colliding with the popped-out wafer, and prevent damage to the wafer. In particular, since it is detected by a reflection type optical sensor, it can be surely detected whether the wafer is an opaque body or a transparent body, and the light projected by the reflection type optical sensor is flat on the wafer. Since it is performed on the surface, stable and highly accurate detection can be performed.

Further, by arranging the reflection type photosensors above and below the opening, sensing is performed from both above and below, so that more accurate detection can be performed. In particular, among the plurality of wafers stored in the cassette, the upper half of the wafer is mainly detected by the upper light sensor, and the lower half of the wafer is mainly detected by the lower light sensor. The area becomes, and highly accurate and stable detection can be performed. Further, by covering the reflective optical sensor with a conductive resin cover that allows light to pass therethrough, it is possible to prevent the cleaning agent, dust, or the like from directly adhering to the optical sensor, and to secure a stable detection function.

[Brief description of drawings]

FIG. 1 is a perspective external view showing an embodiment of a cassette lid attaching / detaching device according to the present invention.

FIG. 2 is a vertical sectional view of a cassette lid attaching / detaching device.

FIG. 3 is a vertical cross-sectional view showing the vicinity of an opening formed in a partition wall forming a part of the cassette lid attaching / detaching device.

FIG. 4 is a rear view of the cassette lid attaching / detaching device viewed from the internal space side for manufacturing semiconductors.

FIG. 5 is a cross-sectional view showing the vicinity of an opening formed in a partition wall forming a part of the cassette lid attaching / detaching device.

FIG. 6 is a cross-sectional view showing another embodiment relating to the arrangement of the reflective photosensor and showing the vicinity of the opening formed in the partition wall.

7A and 7B show a hermetically-sealed cassette that stores wafers, in which FIG. 7A is a perspective external view and FIG. 7B is a perspective view showing the inside of a lid.

[Explanation of symbols]

W wafer S partition 1 cassette 2 cassette body 3 lid 4 biasing arm 10 partition 11 openings 11a upper edge 11b lower edge 20 tables 21 Placement plate 30 shield doors 40 Forward / backward drive mechanism (drive mechanism) 41 Support member 42 Servo motor 43 Lead screw 44 Guide rail 50 mapping sensor 70 Lifting member 80 Lifting drive mechanism (drive mechanism) 81 Servo motor 82 Lead screw 83 Guide shaft 90 Reflective optical sensor 91 Upper light sensor 92 Lower light sensor 100 resin cover 101,102 transparent window 110 hollow

Claims (5)

[Claims] 1. A shield door capable of opening and closing an opening facing a lid of a cassette for storing wafers and holding the lid, and the shield for attaching and detaching the lid and the shield door while holding the lid. A cassette lid attaching / detaching device comprising a drive mechanism for moving a door forward and backward and raising and lowering the door, wherein a reflective optical sensor for projecting light in a direction substantially orthogonal to a main surface of a wafer is provided in the area of the opening. A cassette lid attaching / detaching device characterized by the above. 2. The reflection type optical sensor includes an upper side optical sensor arranged on an upper edge side of the opening and a lower side optical sensor arranged on a lower edge side of the opening. The cassette lid attaching / detaching device according to claim 1, wherein. 3. The upper light sensor and the lower light sensor,
3. The cassette lid attaching / detaching device according to claim 2, wherein the respective optical axes are arranged at positions separated in the direction along the main surface of the wafer. 4. The cassette lid attaching / detaching device according to claim 1, wherein the reflection type optical sensor is covered with a conductive resin cover that allows light to pass therethrough. 5. The detection timing of the reflection type optical sensor is set before the lid and the shield door are moved up and down by the drive mechanism. The cassette lid attaching / detaching device described in.