JPH07335718A - Wafer carrier device - Google Patents

Abstract

PURPOSE:To make it possible to prevent a semiconductor wafer from attraction failure or damage when taking out a semiconductor wafer housed in a carrier cassette. CONSTITUTION:There are installed a carrier cassette 2 where the outer peripheral part of a semiconductor wafer 1 is supported on a cassette jig 5 and a plurality of wafers are vertically housed and a conveying arm 4 which attracts the bottom of the semiconductor wafers 1 and house them to the carrier cassette 2 and takes them out from the carrier cassette 2. There are installed an optical sensor 4b which is installed to a plurality of locations of the conveying arm 4 and which measures the distance between the semiconductor wafer to be conveyed and the conveying arm 4 and a slope angle control unit 7 which controls relative slope position by way of a detection signal transmitted from the optical sensor 4b so that the semiconductor wafer 1 may be positioned in parallel to the conveying arm 4 advancing in the lower part of the semiconductor wafer 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer carrier device for transporting and storing semiconductor wafers, and more particularly to a wafer carrier device capable of preventing wafer damage and wafer suction failure when taking out a semiconductor wafer stored in a carrier cassette. .

[0002]

2. Description of the Related Art Today, in a semiconductor device manufacturing process, a robot is used to store semiconductor wafers in a carrier cassette or to store the stored semiconductor wafers from the viewpoint of production efficiency, labor saving, and quality stabilization. A wafer carrier device for taking out and taking out is widely adopted.

As such a wafer carrier device, for example, "Monthly Se" issued by Press Journal Co., Ltd.
The semiconductor wafer is housed in a carrier cassette with an elevator, as described in "Microconductor World" June 1993, P131-P135.
It is known to take out a semiconductor wafer from a carrier cassette by a wafer transfer robot whose transfer arm is movable in horizontal and vertical directions.

This device has been designed with consideration given to increasing the transfer speed and maintaining the cleanliness in the clean room. In the above-mentioned document, the control technology of the drive unit for driving the transfer arm with high precision and without vibration, and dust removal. Techniques for preventing occurrence have been disclosed.

[0005]

Here, the carrier cassette 1 of the wafer carrier device examined by the present inventors.
The structure of No. 2 will be described with reference to FIG.

This carrier cassette 12 has a frame 12a.
A cassette jig 15 made of, for example, a fluororesin that does not adhere to dust is attached to the inner wall surface of the container, and the semiconductor wafer 11 is supported on the cassette jig 15 to accommodate a plurality of sheets in the vertical direction. The cassette jig 15 may be thermally deformed when exposed to a high temperature. Then,
As shown in FIG. 5, the semiconductor wafer 11 held by the cassette jig 15 and the transfer arm 14 do not have a parallel positional relationship.

If the carrier cassette 12 of the above-mentioned wafer carrier device has such a structure, the transfer arm 14 is provided.
And the semiconductor wafer 11 are not in the parallel position, the transfer arm 14 rises to adsorb the semiconductor wafer 11 from below, and simultaneous contact with the entire surface of them cannot be obtained. The semiconductor wafer 11
May fall. Further, when the carrier arm 14 is inserted between the semiconductor wafers 11 and is to be taken out, even if the carrier cassette 12 is moved by an elevator.
Even if the position is adjusted up and down, there is no room in the upper and lower space into which the transfer arm 14 enters, and the transfer arm 14 may damage or break the semiconductor wafer 11.

[0008] In addition, although the tendency of increasing the diameter of the semiconductor wafer 11 is remarkable today, the amount of deformation of the cassette jig 15 for holding the semiconductor wafer 11 having such a large diameter is further increased during thermal deformation. It is assumed that the semiconductor wafer 11 is not properly sucked and damaged.

Therefore, an object of the present invention is to provide a technique relating to a wafer carrier device capable of preventing a semiconductor wafer suction defect when taking out a semiconductor wafer stored in a carrier cassette.

Another object of the present invention is to provide a technique relating to a wafer carrier device capable of preventing damage to a semiconductor wafer when taking out the semiconductor wafer stored in a carrier cassette.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0012]

The typical ones of the inventions disclosed in the present application will be outlined below.

That is, the wafer carrier device according to the present invention includes a carrier cassette for accommodating a plurality of semiconductor wafers in the vertical direction with the outer peripheral portions of the semiconductor wafers being supported on the cassette jig, and the lower surface of the semiconductor wafer. A transfer arm that adsorbs and stores the semiconductor wafer in and out of the carrier cassette, a distance measurement sensor that is provided at a plurality of positions of the transfer arm and that measures the distance between the semiconductor wafer and the transfer arm that are transferred, and a distance measurement sensor Inclination angle adjusting means is provided for relative adjustment of the inclination position so that the semiconductor wafer and the transfer arm that has entered below the semiconductor wafer are parallel to each other in response to the detection signal.

Further, in the wafer carrier device according to the present invention, the wafer carrier device is provided with a position detecting sensor for detecting the position of the semiconductor wafer housed in the carrier cassette, and the semiconductor wafer is detected by the detection signal of the position detecting sensor. Height adjusting means for adjusting the height of the carrier cassette so that the carrier cassette comes to the take-out position is provided.

In these cases, the distance measuring sensor is an optical sensor for optically measuring the distance between the transfer arm and the semiconductor wafer or an air sensor for measuring the distance between the transfer arm and the semiconductor wafer by air pressure. You can

[0016]

According to the wafer carrier device having the above structure, the semiconductor wafer to be transferred and the transfer arm are adjusted to the parallel position by the tilt angle adjusting means, so that the cassette jig supporting the semiconductor wafer is Even if they are deformed, it is guaranteed that they are always in a parallel positional relationship.

Therefore, when the transfer arm is raised and sucks the semiconductor wafer from below, the two are in simultaneous contact with each other over the entire surface, so that a stable and good suction force can be obtained, which results from a suction failure. It is possible to prevent the semiconductor wafer from dropping during transportation.

Also, when the semiconductor wafers other than the lowermost position stored in the carrier cassette are taken out, the transfer arm can enter between the semiconductor wafers leaving a space in the upper and lower spaces, so that the transfer arm can be used to move the semiconductor wafers. It also eliminates the risk of being damaged or cracked.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a wafer carrier device according to an embodiment of the present invention, FIG. 2 is a side view of the wafer carrier device taken along the line II--II, and FIG. It is a top view of a carrier device.

As shown in FIG. 1, the wafer carrier device of this embodiment has a carrier cassette 2 in which a semiconductor wafer 1 is housed, and a height adjusting section (height adjusting means) provided below the carrier cassette 2. ) 6 and an inclination angle adjusting section (inclination angle adjusting means) 7, and a transfer arm 4 for taking out the semiconductor wafer 1 from the carrier cassette 2 or storing it in the carrier cassette 2. Further, the present apparatus is, for example, for supplying the semiconductor wafers 1 to the exposure apparatus (not shown) one by one.

The carrier cassette 2 is a cassette jig on which the semiconductor wafer 1 is placed on the inner wall surface of the frame body 2a which has a substantially U-shaped horizontal cross section and is opened toward the transfer arm 4 located laterally. 5 is attached. A cassette jig 5 for supporting and storing the outer peripheral surface of one semiconductor wafer 1.
Consists of a pair, one end of which is fixed to the inner wall surfaces facing each other and the other end of which is fixed to the other inner wall surface. In this cassette jig 5, a plurality of transfer arms 4 are attached in the up-and-down direction with an interval in which the transfer arms 4 can be inserted between the accommodated semiconductor wafers 1. The frame 2a of the carrier cassette 2 is made of, for example, metal such as iron, and the cassette jig 5 is made of, for example, fluororesin from the viewpoint of preventing dust adhesion due to generation of static electricity.

It is provided below the carrier cassette 2,
The height adjusting section 6 for adjusting the height is provided so that an upper pedestal 6a and a lower pedestal 6b, which are diagonally divided into two, are in slidable contact with each other on an inclined surface, and the upper pedestal 6a is illustrated. The lower pedestal 6b is screwed to the rod 6d of the pulse motor 6c having a ball screw, for example, because the locking member does not move laterally.
Therefore, when the pulse motor 6c rotates, this rotational force is converted into thrust and the lower pedestal 6b is moved laterally.
Then, the upper pedestal 6 that is in contact with the lower pedestal 6b on the slope
a slides along with the movement of the lower pedestal 6b and is moved in the vertical direction.

Further, the tilt angle adjusting portion 7 for adjusting the tilt angle of the carrier cassette 2 is provided so as to be able to move up and down while protruding above the upper pedestal 6a and supporting the base portion 2b of the carrier cassette 2, for example, three. Support legs 7a (Fig. 3) of
And a pulse motor 7b that raises and lowers them independently. Therefore, the pulse motor 7b
By raising or lowering one or two of the support legs 7a, the inclination angle of the carrier cassette 2 can be three-dimensionally changed.

For example, the semiconductor wafer 1 housed in the carrier cassette 2 is taken out in order from the lower stage and carried to the exposure device, and the semiconductor wafer 1 after the exposure is housed in the carrier cassette 2. The target semiconductor wafer 1 is laterally inserted into the lower position, lifted, and simultaneously vacuum-sucked. A suction pad 4a for sucking the semiconductor wafer 1 is provided on the upper surface. Optical sensors (distance measuring sensors) 4b that optically measure the distance between the semiconductor wafer 1 to be transferred and the transfer arm 4 are provided at, for example, four positions on the upper surface. As shown in FIG. 2, the optical sensor 4b is composed of a light emitting portion 4b ₁ and a light receiving portion 4b ₂ which are integrally formed, and each optical sensor 4b emits light of different wavelengths. The distance from the semiconductor wafer 1 is measured by irradiating the semiconductor wafer ₁ from 4b ₁ and detecting the amount of reflected light by the light receiving section 4b ₂ . Further, on the opening side of the carrier cassette 2, a position detection sensor 9 for detecting the semiconductor wafer 1 to be transferred is provided.

The optical sensor 4b and the position detection sensor 9 described above are electrically connected to the control unit 10, and the control unit 10 further controls the pulse motor 6c for adjusting the height of the carrier cassette 2 and the inclination angle of the carrier cassette 2. Is electrically connected to the pulse motor 7b for adjusting the. In the control unit 10, the detection signals of the optical sensor 4b and the position detection sensor 9 are arithmetically processed so that the semiconductor wafer 1 to be transferred is at substantially the same height as the transfer arm 4, that is, the taking-out position, and the transfer arm 4 is operated. The height and the inclination angle of the carrier cassette 2 are corrected so that the carrier cassette 2 is located in parallel with the semiconductor wafer 1.

According to such a wafer carrier device,
The semiconductor wafer 1 is transported as follows.

First, the position detection sensor 9 detects the semiconductor wafer 1 at the lowermost position to be transferred, and a detection signal is sent to the control unit 10. This detection signal is arithmetically processed by the control unit 10, the pulse motor 6c is rotated by a required amount, the lower pedestal 6b is laterally moved, the upper pedestal 6a is vertically moved, and the carrier cassette 2 is accommodated in the semiconductor. The wafer 1 is adjusted to the height at which it is taken out by the transfer arm 4.

Next, the transfer arm 4 enters below the semiconductor wafer 1 and temporarily stops, and the four photosensors 4b detect the distance between the transfer arm 4 and the semiconductor wafer 1.
This detection signal is sent to the control unit 10 to calculate the tilt correction component, whereby one or two of the pulse motors 7b in the tilt angle adjusting unit 7 are rotated by a required amount to raise and lower the support legs 7a, The inclination angle of the carrier cassette 2 is three-dimensionally corrected so that the semiconductor wafer 1 and the transfer arm 4 have a parallel positional relationship. Note that the correction amount at this time is fed back to the pulse motor 6c of the height adjusting unit 6 to readjust the fluctuation of the height caused by the change of the inclination angle,
It is controlled so as to fall within the threshold value of the height reference value which is previously input to the control unit 10.

After the height and tilt angle of the carrier cassette 2 are adjusted in this way, the transfer arm 4 is raised and the semiconductor wafer 1 to be transferred is lifted.

At this time, since the position of the semiconductor wafer 1 and the transfer arm 4 to be transferred are adjusted by the tilt angle adjusting section 7, the cassette jig 5 supporting the semiconductor wafer 1 is deformed by, for example, heat. Even if they do, it is guaranteed that the two will always have a parallel positional relationship. Therefore, when the transfer arm 4 moves up and sucks the semiconductor wafer 1 from below, the two are in simultaneous contact with each other over their entire surfaces. Therefore, a stable and good suction force can be obtained, and it is possible to prevent the semiconductor wafer 1 from dropping during the transportation.

Further, for example, when the semiconductor wafer 1 stored in the carrier cassette 2 other than the lowermost position is taken out, the transfer arm 4 can enter between the semiconductor wafers 1 leaving a space in the upper and lower spaces. Transport arm 4
Therefore, there is no possibility that the semiconductor wafer 1 is damaged or broken.

In the wafer carrier device of this embodiment, the adjustment of the tilt angle of the carrier cassette 2 as described above is performed only on the semiconductor wafer at the head of the lot.
Only the height adjustment is performed from the second semiconductor wafer 1. However, when the amount of deformation of the cassette jig 5 is large or the deformed state is different for each cassette jig 5, it is necessary to adjust the inclination angle of the carrier cassette 2 for all the semiconductor wafers 1. preferable. Further, the inclination angle of the carrier cassette 2 can be adjusted for every fixed number of sheets.

Then, the semiconductor wafer 1 thus held by the transfer arm 4 is transferred to an exposure sequence section (not shown).

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, the mechanism of the height adjusting section 6 and the inclination angle adjusting section 7 is not limited to the one according to the present embodiment, but various mechanisms can be used as long as the height and the inclination angle of the carrier cassette 2 can be adjusted. It is possible to adopt the mechanism of. For example, for the tilt angle adjusting unit 7, it is possible to adopt a piezo mechanism using a piezoelectric element. Further, even when the mechanism according to the present embodiment is adopted, the number of the support legs 7a is not limited to three as far as the tilt angle adjusting section 7 is concerned. That is, the reason why the number of the support legs 7a is three is from the viewpoint of easy adjustment of the inclination angle, and the number of the support legs may be four or more, and one support leg 7a may be provided at the center or both ends may be provided. It is also possible to provide one by one.

The optical sensor 4b as a distance measuring sensor provided on the transfer arm 4 is not limited to this, and for example, as shown in FIG.
Air is blown onto the semiconductor wafer 1 and the semiconductor wafer 1
It is also possible to use an air sensor 24b or the like that measures the distance between the carrier arm 4 and the carrier arm 4. That is, as long as the distance between the transfer arm 4 and the semiconductor wafer 1 can be measured in a non-contact state, various other distance measuring sensors other than the above can be used. The number of distance measuring sensors provided on the transfer arm 4 is four in this embodiment, but any number can be arbitrarily provided.

Further, in the present embodiment, the height and the tilt angle are adjusted by the height adjusting section 6 and the tilt angle adjusting section 7 provided below the carrier cassette 2, respectively. Either one or both of them can be carried by the transfer arm 4. That is,
In the present invention, the height or the inclination angle between the transfer arm 4 and the semiconductor wafer 1 may be adjusted relatively, and the adjustment is not limited to only one side.

The wafer carrier device of this embodiment is used to transfer the semiconductor wafer 1 to the exposure device, but the present invention is not limited to this, and semiconductor wafers of various cases in the manufacturing process of the semiconductor device. It is possible to adapt to storage and transportation of 1.

[0040]

The effects obtained by the typical ones of the inventions disclosed in this application will be briefly described as follows.

(1) That is, according to the wafer carrier device of the present invention, the relative tilt angle of the semiconductor wafer to be transferred and the transfer arm are adjusted by the tilt angle adjusting section so that they are always in parallel position. . Therefore, even if the cassette jig supporting the semiconductor wafer is deformed, it is guaranteed that the two are in a parallel positional relationship.

(2) Therefore, when the transfer arm moves up and sucks the semiconductor wafer from below, the two are in contact with each other at the same time, so that suction failure is prevented and a stable and good suction force is obtained. Therefore, it becomes possible to prevent the semiconductor wafer from dropping during the transportation.

(3) Further, according to the above (1), even when the semiconductor wafers other than the lowermost position housed in the carrier cassette are taken out, the transfer arm enters between the semiconductor wafers leaving a space in the upper and lower spaces. Therefore, there is no possibility that the semiconductor wafer is damaged or broken by the transfer arm.

(4). And, due to (1) to (3), the defect rate of the semiconductor wafer is reduced.

(5) Further, due to (1) to (3), even if the deformation amount is large like a cassette jig for holding a semiconductor wafer having a large diameter, it is possible to surely prevent the defective suction and the damage to the semiconductor wafer. It becomes possible to do.

[Brief description of drawings]

FIG. 1 is a perspective view showing a wafer carrier device according to an embodiment of the present invention.

FIG. 2 is a partially cutaway side view of the wafer carrier device taken along line II-II.

FIG. 3 is a plan view of the wafer carrier device.

FIG. 4 is a front view showing a carrier cassette of a wafer carrier device examined by the present inventors.

5 is an explanatory diagram showing a positional relationship between the carrier cassette and the transfer arm in FIG. 4. FIG.

FIG. 6 is an essential part explanatory view showing a wafer carrier device according to another embodiment of the present invention.

[Explanation of symbols]

1 semiconductor wafer 2 carrier cassette 2a frame 2b base 4 transfer arm 4a suction pad 4b optical sensor (distance measuring sensor) 4b ₁ light emitting unit 4b ₂ light receiving unit 5 cassette jig 6 height adjusting unit (height adjusting means) 6a Upper pedestal 6b Lower pedestal 6c Pulse motor 6d Rod 7 Tilt angle adjusting part (tilt angle adjusting means) 7a Support leg 7b Pulse motor 9 Position detection sensor 10 Control part 11 Semiconductor wafer 12 Carrier cassette 12a Frame 14 Transfer arm 15 Cassette jig 24b Air sensor (distance measuring sensor)

Front Page Continuation (72) Inventor Kazuaki Tokita 5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Incorporated company Hitachi Ltd. Semiconductor Division

Claims (4)

[Claims] 1. A carrier cassette for accommodating a plurality of semiconductor wafers in a vertical direction with each outer peripheral portion of the semiconductor wafer supported on a cassette jig; A transfer arm that stores and takes out the carrier cassette, a distance measurement sensor that is provided at a plurality of positions of the transfer arm, and measures a distance between the semiconductor wafer to be transferred and the transfer arm, and a detection signal of the distance measurement sensor. , A wafer carrier device comprising: a tilt angle adjusting means for adjusting a relative tilt position so that the semiconductor wafer and the transfer arm that has entered below the semiconductor wafer are in parallel positions. . 2. The wafer carrier device according to claim 1,
A position detection sensor for detecting the position of the semiconductor wafer housed in the carrier cassette, and a detection signal of the position detection sensor adjusts the height of the carrier cassette so that the semiconductor wafer comes to the take-out position by the transfer arm. A wafer carrier device, wherein height adjusting means for adjusting is provided. 3. The wafer carrier device according to claim 1, wherein the distance measuring sensor is an optical sensor that optically measures a distance between the transfer arm and the semiconductor wafer. 4. The wafer carrier device according to claim 1, wherein the distance measuring sensor is an air sensor that measures a distance between the transfer arm and the semiconductor wafer by air pressure.