WAFER STORAGE CARRIER
It is an object of the invention to provide a wafer storage carrier that makes it possible to prevent wafers from being damaged or broken, regardless of the state of wafer warpage. A top plate and two side wall plates secured to left and right edges of the top plate describe two rectangular open-ended sides. One of these rectangular open-ended sides is closed off by a rear wall plate. At least two support rods constituting a wafer support shelf are affixed to a central portion of the rear wall plate with respect to the transverse direction, extending toward the other rectangular open-ended side.
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1. Field of the Invention
The present invention relates to a wafer storage carrier for accommodating and transporting semiconductor wafers.
2. Description of the Related Art
Semiconductor wafers (hereinafter, simply referred to as “wafer(s)”) used as a material for semiconductor elements are obtained by thinly slicing ingots made of a substantially cylindrical silicon monocrystal to produce disk-shaped plates having a prescribed thickness. Wafers are typically manufactured at a thickness of approximately 0.5 to 1.0 mm in order to make them easier to handle during the semiconductor manufacturing steps, but thin wafers having a thickness of 150 μm or less are also produced to accommodate the dimensional and characteristic requirements of semiconductor devices.
Wafer storage carriers have conventionally been used to prevent contact between wafers when they are stored or moved between manufacturing steps used to manufacture semiconductor elements. A reason wafer storage carriers are used is to avoid any problems arising as a result of a wafer surface getting scratched when coming into contact with another wafer, the wafer breaking, the wafer surfaces electrostatically or otherwise sticking together, or other similar circumstances. Another reason is to allow a plurality of sliced wafers to be readily conveyed one at a time to the apparatuses used in a subsequent step.
Typical wafer storage carriers have a substantially cubic structure, with an opening present on one side and a space allowing the wafer to be accommodated inside the cube. For example, a wafer storage carrier 1 shown in
In Patent Document 1, there is disclosed a wafer heat treatment apparatus for supporting both ends and the central portion of the wafer, thereby making it possible to prevent the wafer from warping during heat treatment.
[Patent Document 1] W02004/001835
SUMMARY OF THE INVENTIONThe structures of the heat treatment apparatus disclosed in the Patent Document 1 and the wafer storage carrier 1 shown in
In a case where the wafer W is to be inserted into the storage carrier, the wafer W is typically inserted with the central portion supported. However, the position of the central portion and end portions of the wafer W with respect to the vertical direction will differ if the weight and finished configuration at the time of processing cause the wafer W to be in a warped state. Therefore, even in a case that the central portion of the wafer W is inserted into the storage carrier, both end portions of the wafer W might come into contact with the support portions of the storage carrier. The wafer W can be scratched or broken as a result of such contact.
Another problem with the wafer storage carrier 1 shown in
With the foregoing aspects of view, it is an object of the present invention to provide a wafer storage carrier that makes it possible to prevent wafer damage or breakage, regardless of the state of wafer warping.
To solve the problems, there is provided a wafer storage carrier comprising: a flat top plate; side wall plates secured to left and right ends of the top plate and disposed opposite each other; a rear wall plate for closing off one of two rectangular open-ended sides described by the top plate and the side wall plates; and a wafer support shelf having at least two support rods that are affixed in a central portion of the rear wall plate along a transverse direction and that extend towards the other rectangular opening surface.
The plane in which the wafer is supported by the wafer support shelf may be parallel to the top plate. There may be a plurality of wafer support shelves.
The support rods are made of metal and are clad in a Teflon® tube. The support rods may have a circular shape in cross-section.
The side wall plates and the rear wall plate may be capable of being detached from the top plate.
The wafers can be prevented from being damaged or broken, regardless of how warped they are, because the at least two support rods constituting the wafer support shelf and extending toward one of the two rectangular open-ended sides described by the two side wall plates secured to the top plate and the left and right edges thereof are affixed in the transversely central portion of the rear wall plate for closing off the other rectangular open-ended side.
DESCRIPTION OF THE PREFERRED EMBODIMENTSEmbodiments of the present invention will be described in detail below with reference to the accompanying drawings.
EMBODIMENT 1First, a wafer storage carrier 10 used as an embodiment of the present invention will be described in detail with reference to
A handle portion 22 for allowing the wafer storage carrier 10 to be readily carried is anchored to the top surface of top plate 11 (the surface opposite the support area 21). The handle portion 22 may, for example, be shaped substantially like the letter “U.”
A stopper 23 that extends along the Z-axis direction and has one end secured to the top plate 11 has another end secured to a prescribed location on the left bottom plate 17 and the right bottom plate 18. As shown in
A rectangular opening 24 that extends in the direction of the Z-axis is provided in the central portion of the rear wall plate 16 with respect to the direction of the X-axis. The rectangular opening 24 is provided so that a sensor or other device can be used to confirm therethrough whether or not a wafer is supported in the support area 21. A plurality of the support rods 25 that flank the opening 24 are affixed in the central portion of the rear wall plate 16 with respect to the transverse direction (i.e., the central portion in the direction of the X-axis). The support rods 25 extend from the rear wall plate 16 toward the side where the rectangular open-end sides are not closed off (the “−” side along direction Y). The support rods 25 are preferably made of metal and clad in a Teflon® tube. The reason for this is that since the support rods 25 contact the wafers, using unclad metal rods makes it likely that the wafer surfaces will get contaminated by the metal. In order to reduce the area of contact with the wafer, the cross-portion of the support rods 25 along the X-Z plane is preferably circular in shape. There now follows a description of the locations where the support rods 25 are to be embeddedly affixed in the rear wall plate 16.
A method for embeddedly affixing the support rods 25 into the rear wall plate will now be described in detail with reference to
As indicated in
The diameter of a support portion 25a of the support rods 25 is slightly smaller than the diameter of the small opening 26a, and the diameter of the head portion 25b of the support rods 25 is slightly smaller than the diameter of the large opening 26b of the through-hole 26. By “slightly smaller” is meant that the diameters are small enough so that the support rods 25 can be insertably fitted into the through-holes 26, but there will be no instance of the support rods 25 being readily displaced in the direction of the Z-axis (e.g., slanting downward towards the “−” side in the direction of the Y-axis).
Accordingly, when the support rods 25 are insertably fitted into the through-holes 26 in the direction of arrow 3a, a head portion 25b of the support rods 25 will contact the step portion formed by the small opening 26a and the large opening 26b of the through-holes 26; therefore, the support rods 25 will be incapable of advancing any further towards the support area 21 than as shown in
In a state where the support rods 25 are insertably fitted into the through-holes 26, the size of the head portion 25b may be adjusted so that the rear wall plate 16 and the head portion 25b will be coplanar. It is also possible to provide a prescribed groove to a part of the surface of the support rods 25 and the surface of the through-holes 26, and screw the support rods 25 into the through-holes 26.
There shall now be provided a detailed description of how the wafers are loaded, removed, and supported, with reference being made to
As shown in
Twelve support rods 25 are linearly affixed on the rear wall plate 16 at a predetermined spacing in the direction of the Z-axis. Specifically, the twelve support rods 25 are affixed in a line in the direction of the Z-axis; i.e., the twelve support shelves 41 are formed by the support rods 25 in the support area 21. The number of support rods 25 is not limited to the number indicated in
Since the support rods 25 flank the opening 24 and are affixed in the central portion of the rear wall plate 16 with respect to the transverse direction, the edges of wafers to be loaded will not come into contact with the members constituting the support area 21, even in a case that the wafer warps upwards (the “+” side of the Z-axis) or downwards (the “−” side of the Z-axis). Accordingly, no consideration needs to be given to the position of the wafer edge in the direction of the Z-axis when the wafer is to be loaded, and it is possible to readily position and install the wafer based on the position of the central portion of each wafer in the Z-axis direction.
As shown in
The gap between the ends of the differently warped wafer W2 and wafer W3 (i.e., the distance between the wafers W2 and W3) is small, but the gap in the central portion of the wafer is approximately the same or slightly larger. The gap in the central portion of the wafer is equivalent or greater than the pitch of the support rods 25; therefore, the arm of the wafer loading/unloading apparatus or other components do not contact adjacent wafers during the wafer unloading step. Accordingly, wafer warpage need not be a concern in the wafer removal process. Furthermore, since contact with the wafer edge is prevented, the width of the pitch of the support rods 25 may be set from approximately 4.76 to 9.52 mm, depending on the state of wafer warpage. For example, the through-holes 26 may be provided at a spacing of 2.38 mm or less along the Z-axis direction of the rear wall plate 16, and the position where the support rods 25 are to be insertably fitted may be determined according to the state of wafer warpage.
The gap between the edges of the wafer W3 and the wafer W4, which have different warp directions, is large, but in the central portion of the wafer the gap is approximately the same or slightly narrower than the pitch of the support rods 25. However, since the wafers are supported by the support rods 25 in the central portion, the degree to which warping causes the wafer to be displaced in the direction of the Z-axis in the central portion is extremely small, and no problems are presented in terms of the arm or other components of the wafer loading/unloading apparatus making contact with an adjacent wafer during the wafer removal step. Accordingly, wafer warpage need not be a concern during the wafer removal step, even when the wafers are supported as described above.
The central portion described above is preferably a position that is close to the center of the rear wall plate 16 in the direction of the X-axis, but includes conventional positions other than for supporting the wafer edges. Specifically, the support rods 25 may be affixed in a position of the rear wall plate 16 closer to the edge than the center in the direction of the X-axis.
Since the wafer storage carrier is secured using a plurality of screws, individual members can be removed, and broken ones individually replaced. Moreover, the fact that each member is removable means that individual members can be cleaned one at a time.
As mentioned above, according to the wafer storage carrier 10 of the present embodiment, wafer damage or breakage can be prevented, regardless of how warped the wafers are, because the at least two support rods 25 constituting the wafer support shelf 41 and extending toward one of the two rectangular open-ended sides described by the left side wall plate 12 and the right side wall plate 13 secured to the top plate 11 and the left and right edges of top plate 11 are affixed in the transversely central portion of the rear wall plate 16 for closing off the other rectangular open-ended side.
EMBODIMENT 2In Embodiment 1, two rows of support rods 25 are formed on the rear wall plate 16 flanking the opening 24 along the Z-axis; however, the support rods 25 may also be embeddedly affixed so as to form two or more rows of support rods 25 on each of the left and right sides of the opening 24. A wafer storage carrier of such description will be described in detail below with reference to
As shown in
Twelve support rods 25 are linearly provided at a predetermined spacing in the direction of the Z-axis, as in Embodiment 1; therefore, four rows of support rods 25 are formed in the direction of the Z-axis.
The wafer storage carrier 50 of Embodiment 2 has a larger number of support rods 25 in the X-axis, giving it an advantage over the wafer storage carrier 10 of Embodiment 1 in that the wafer can be more stably held.
As shown in
This application is based on Japanese Patent Application No. 2008-155128 which is hereby incorporated by reference.
Description of Reference Numerals
- 10 Wafer storage carrier
- 11 Top plate
- 12 Left side wall plate
- 13 Right side wall plat
- 16 Rear wall plate
- 17 Left bottom plate
- 18 Right bottom plate
- 20 Linking rod
- 21 Support area
- 22 Handle portion
- 23 Stopper
- 24 Opening
- 25 Support rod
- 26 Through-hole
- W1-W5 Wafer
This application is based on Japanese Patent Application No. 2008-155128 which is hereby incorporated by reference.
Claims
1. A wafer storage carrier comprising:
- a flat top plate;
- side wall plates secured to left and right ends of said top plate so as to face one another;
- a rear wall plate for closing off one of two rectangular open-ended sides formed by said top plate and said side wall plate; and
- a wafer support shelf having at least two support rods that are embeddedly affixed in a central portion of the said rear wall plate along a transverse direction and that extend towards another one of said rectangular open-ended sides.
2. The wafer storage carrier of claim 1, wherein a wafer support surface of said wafer support shelf is parallel to said top plate.
3. The wafer storage carrier of claim 1, wherein a plurality of wafer support shelves are present.
4. The wafer storage carrier of claim 1, wherein the support rods are made of metal and are clad in a Teflon® tube.
5. The wafer storage carrier of claim 3, wherein said support rods are circular in cross-section.
6. The wafer storage carrier of claim 1, wherein said side wall plate and said rear wall plate are capable of being detached from said top plate.
Type: Application
Filed: Jun 4, 2009
Publication Date: Dec 17, 2009
Applicant: OKI SEMICONDUCTOR CO., LTD. (Tokyo)
Inventor: Katsuhiro Yoshino (Miyazaki)
Application Number: 12/478,046
International Classification: B65D 85/00 (20060101);