JP2009170780A - Wafer storage container with cushion sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer storage container with a cushion sheet, which can prevent a semiconductor wafer from being broken due to an impact during transportation or under a repetitive changing condition while always keeping the wafer flat, and by which the semiconductor wafer is safely and easily taken out without being damaged when taking out the wafer. <P>SOLUTION: A self-suction part detachably sucking a semiconductor wafer W is formed on the surface of a wafer placing cushion sheet, and a non-suction part always kept away from the semiconductor wafer W without sucking the semiconductor wafer W is formed on the same surface thereof. The area density in the self-suction part of the wafer placing cushion sheet sucking a center of the semiconductor wafer is made large, and the area density of the self-suction part of the wafer placing cushion sheet sucking a periphery of the semiconductor wafer is made small. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wafer storage container with a wafer mounting cushion sheet used for transporting or storing semiconductor wafers.

  In a semiconductor manufacturing process, a semiconductor wafer is stored in a wafer storage container so that the semiconductor wafer is not damaged or soiled when it is transported or stored between processes or in each process. The As such a wafer storage container, a plurality of wafer mounting trays are overlapped and formed between two wafer mounting trays so that semiconductor wafers can be stored safely one by one. There has been proposed a structure in which semiconductor wafers are individually housed one by one in an inner space (for example, Patent Document 1).

In addition, in order to safely store a fragile semiconductor wafer that has become extremely thin (for example, the thickness of the semiconductor wafer is 200 microns or less) as in recent years, it is formed between two wafer mounting trays. A wafer storage container with a cushion sheet has been proposed in which one semiconductor wafer is sandwiched between two cushion sheets in an inner space. By sandwiching the semiconductor wafer between the two cushion sheets, the semiconductor wafer is prevented from being damaged by an external force such as vibration or impact (for example, Patent Document 2).
JP 2003-168731 A JP2005-191419

  The semiconductor wafer is flat when sandwiched between the two cushion sheets between the two stacked wafer mounting trays. However, the wafer mounting tray is separated from the upper and lower sides to form a semiconductor wafer. If the semiconductor wafer is not sandwiched between the cushion sheets, the semiconductor wafer will be warped due to the presence of internal stress, etc., and if such state changes are repeated many times, the semiconductor wafer may be damaged. is there. Therefore, it is conceivable that the semiconductor wafer is adhered to the cushion sheet below the semiconductor wafer so that the semiconductor wafer is always kept flat, but when the semiconductor wafer becomes extremely thin, the semiconductor wafer is peeled off from the cushion sheet. There is a possibility that the semiconductor wafer may be damaged by taking out the adsorption force when taking out.

  The present invention not only prevents damage to the semiconductor wafer due to impact during transportation, but also keeps the semiconductor wafer in a flat state in which the flat state and the warped state are not repeated. It is an object of the present invention to provide a wafer storage container with a cushion sheet that can prevent the occurrence of damage and can be safely and easily taken out without damaging the semiconductor wafer.

  In order to achieve the above object, the wafer storage container with a cushion sheet according to the present invention has a plurality of wafer mounting trays for stacking and holding semiconductor wafers one by one and is placed on each wafer mounting tray. The semiconductor wafer is stored in an inner space formed between the wafer placement tray and the wafer placement tray stacked adjacent to the upper side, and the semiconductor wafer on the upper surface of each wafer placement tray In a wafer storage container with a cushion sheet in which an elastic wafer mounting cushion sheet is disposed at the mounting position, the self-adsorbing part for detachably adsorbing the semiconductor wafer and the semiconductor wafer are adsorbed on the surface of the wafer mounting cushion sheet A non-adsorbing portion that maintains a separated state without being formed is formed. By changing the area density of the self-adsorption part that adsorbs the semiconductor wafer, the adsorption force of the semiconductor wafer by the wafer placement cushion sheet is adjusted according to the location of the wafer placement cushion sheet. In particular, the area density of the self-adsorption portion at the center of the wafer mounting cushion sheet that adsorbs the wafer center is higher than the area density of the self-adsorption portion at the outer periphery of the wafer mounting cushion sheet that adsorbs the wafer outer periphery. Yes. As a method of changing the area density of the self-adsorption part, there is a method of changing the ratio of the area of the self-adsorption part and the area of the non-adsorption part in the region.

  Further, the self-adsorption part may be formed by a number of fine suction cups, and the fine suction cup and the semiconductor wafer may be in a state of being adsorbed and fixed by pressing the fine suction cups against the semiconductor wafer. The portion may be formed of a foamed elastomeric polymer material, a foamed rubber polymer material, or a foamed urethane polymer material having elasticity.

  The wafer mounting cushion sheet may be detachably attached to the wafer mounting tray, and an elastic wafer pressing cushion sheet for pressing the semiconductor wafer against the wafer mounting cushion sheet is provided. It may be arranged on the back side of the tray.

  According to the present invention, the self-adsorption portion that is detachably adsorbed to the semiconductor wafer is formed on the surface of the wafer mounting cushion sheet, thereby preventing the semiconductor wafer from being damaged due to an impact during transfer. In addition, the semiconductor wafer can always be kept in a flat state in which the flat state and the warped state are not repeated, thereby preventing the semiconductor wafer from being damaged due to a state change. In addition, a self-adsorption portion that detachably adsorbs the semiconductor wafer and a non-adsorption portion that keeps the semiconductor wafer separated without being adsorbed are formed on the surface of the wafer mounting cushion sheet, and adjustment of the adsorption force Is not adjusted only by the sucker diameter of the adsorbent, but the adsorption force that the self-adsorption part of the cushion sheet adsorbs the semiconductor wafer is adjusted by the area density of the self-adsorption part, so it is easy to control the adsorption force In addition, it becomes easy to change the adsorption force depending on the location in the cushion sheet.

  For example, by making the area density of the self-adsorption part of the wafer mounting cushion sheet adsorbing the outer peripheral part of the semiconductor wafer smaller than the area density of the self-adsorption part of the wafer mounting cushion sheet adsorbing the center part of the semiconductor wafer, The adsorption force of the wafer mounting cushion sheet that adsorbs the outer peripheral portion of the semiconductor wafer can be made smaller than the adsorption force of the wafer mounting cushion sheet that adsorbs the central portion of the semiconductor wafer. As a result, the wafer mounting cushion sheet can be easily peeled off from the outer edge portion of the semiconductor wafer, and the semiconductor wafer can be taken out safely and easily without being damaged. For example, when the semiconductor wafer is peeled off from the self-adsorption part, air enters the self-adsorption part from its outer edge part and the adsorbed state is released, and as the semiconductor wafer peels off toward the central part, Since air enters the suction portion and the suction state is released, the semiconductor wafer can be safely and easily taken out without being damaged.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 2 shows the overall structure of the wafer storage container with a cushion sheet, and a plurality of wafer mounting trays 1 for placing and holding ultrathin semiconductor wafers W formed in a disc shape are in a horizontal state. They are placed one above the other. FIG. 2 shows a state in which a part of the plurality of stacked wafer placement trays 1 is separated on the way. A coupling groove 3 for coupling to a mechanical interface device (not shown) is formed in the base tray 2 attached to the upper and lower ends of the plurality of stacked wafer mounting trays 1.

  Each wafer mounting tray 1 is formed of a plastic material such as polycarbonate resin, for example, and the plurality of wafer mounting trays 1 are overlapped, so that the semiconductor wafers W placed on the wafer mounting tray 1 are formed. Then, the wafer is placed in an inner space formed between each wafer placement tray 1 and the wafer placement tray 1 stacked adjacently on the upper side thereof. At that time, the semiconductor wafer W is placed on a wafer mounting cushion sheet (hereinafter abbreviated as “mounting cushion”) 25 attached to the upper surface of the wafer mounting tray 1.

  The mounting cushion 25 is formed with a self-adsorption portion that is detachably adsorbed to the semiconductor wafer W and a non-adsorption portion that maintains a separated state without being adsorbed to the semiconductor wafer W. A region 25A having a large area density of the adsorbing portion and a region 25B having a small area density of the self-adsorbing portion are formed. Details thereof will be described later. Reference numeral 6 denotes an annular seal member made of a resilient member disposed so as to surround the circumference of the mounting cushion 25 over the entire circumference at a position outside the mounting cushion 25. Reference numeral 7 denotes a gripping portion formed at a 180 ° symmetrical position on the outer edge of each wafer mounting tray 1 so that the wafer mounting tray 1 can be individually held by a mechanical device.

  On the upper surface side of each wafer mounting tray 1, for example, four coupling holes 8 are provided at positions closer to the outer edge than the annular seal member 6 to be coupled to the wafer mounting tray 1 positioned above the wafer mounting tray 1. It is formed in the place. Correspondingly, coupling hooks 9 that are detachably engaged with the respective coupling holes 8 are formed to project downward from the back surface of each wafer mounting tray 1 at four locations. In this way, a tray coupling mechanism for releasably coupling a plurality of wafer mounting trays 1 at an arbitrary overlapping position in a state where the plurality of wafer mounting trays 1 are overlapped with each other includes a coupling hole 8 and a coupling hook 9. The engagement between the coupling hole 8 and the coupling hook 9 is released by inserting a hook removing key or the like (not shown) from the key insertion hole 10 formed on the side surface of the wafer loading tray 1 and elastically deforming the coupling hook 9. Can be done.

  FIG. 3 shows a state where the semiconductor wafer W is placed on one of the wafer placement trays 1. However, in order to illustrate the cross section of the coupling hook 9 and the like in one drawing, the drawings of different cross sectional positions are shown in combination. The annular seal member 6 is disposed in a state where the lower half portion is fitted in an annular groove formed at a position slightly inside the outer edge of the upper surface of each wafer mounting tray 1. Each wafer mounting tray 1 is formed in a dish shape in which a portion located on the inner side of the annular seal member 6 falls downward on both the upper and lower surfaces, and a mounting cushion 25 is disposed on the bottom surface 13 thereof.

  The mounting cushion 25 is large enough to be mounted on almost the entire surface of the semiconductor wafer W by a material that does not have a chemical adverse effect on the semiconductor wafer W in all portions, for example, a material in which the generation of impurity gas is not more than a specified value. It is formed in a disc shape.

  The mounting cushion 25 shown in FIG. 3 is a two-layer type mounting cushion. That is, the back surface of the mounting cushion 25 (the surface facing the bottom surface 13 of the wafer mounting tray 1) is formed of a base material sheet 25C made of a material such as PET (polyethylene terephthalate), and the front surface (semiconductor On the side facing the wafer W, as shown in FIG. 4, a region 25B having a small area density of the self-adsorbing portion surrounds the entire area 25A around the region 25A having a large area density of the self-adsorbing portion. The two layers on the front side and the back side are laminated and integrated.

  As shown in FIG. 3, in this embodiment, the base sheet 25 </ b> C is bonded to the bottom surface 13 of the wafer loading tray 1. However, the mounting cushion 25 is attached to the bottom surface 13 of the wafer mounting tray 1 by attaching (or detachably attaching) the base sheet 25C to a frame or a pin that is detachable. It can be configured to be arbitrarily detachable from the bottom surface 13. Alternatively, the mounting cushion 25 has a three-layer structure, and a disk-shaped sheet (or layer) composed of a region 25A having a large area density of the self-adsorbing portion on the surface side and a region 25B having a small area density of the self-adsorbing portion. Also by stacking and integrating the same layers on the back surface side of the base sheet 25C, the mounting cushion 25 can be configured to be detachable from the wafer mounting tray 1 so that it can be easily cleaned or replaced. it can. In this case, it is necessary to set the suction force for the wafer mounting tray 1 to be larger than the suction force for the semiconductor wafer W. For example, the area density of the self-adsorption part in the surface layer of the base sheet 25C (the ratio of the area occupied by the self-adsorption part to the total surface area) is the area of the self-adsorption part in the back layer of the base sheet 25C. What is necessary is just to make it smaller than a density (ratio of the area which the self-adsorption part accounts with respect to the total area of a back surface).

  The self-adsorption part described in the present invention means a part where the material itself adsorbs a flat plate such as a semiconductor wafer. For example, FIG. 10 is a diagram showing the structure of the adsorption function layer in the wafer mounting cushion sheet of the present invention. As shown in FIG. 10, there are a large number of foam layers 41 (referred to as adsorption function layers). Among the formed bubbles 5h, each of the bubbles 5h ′ opening toward the outside air at the surface position of the adsorption function layer functions as a fine suction cup. That is, by pressing the flat plate 1 such as a semiconductor wafer disposed in contact with the adsorption function layer 41 against the adsorption function layer 41, the bubbles 5h 'opened toward the outside air contract. (The part without bubbles is 5n.) After that, when the force that pressed the semiconductor wafer etc. disappeared or weakened and the bubbles recovered to the original state or close to it, the inside of the bubbles became decompressed. The semiconductor wafer 1 is adsorbed. Therefore, the self-adsorption portion is a region of the adsorption function layer 41 including bubbles that open toward the outside air at the surface position of the mounting cushion. Note that when an external force (for example, a force for lifting the semiconductor wafer or the like upward) is applied to the self-adsorption portion, the semiconductor wafer or the like is not adsorbed in the portion 5n without bubbles. Outside air enters from the portion toward the bubble, the reduced pressure state in the bubble 5h ′ is eliminated, and the semiconductor wafer or the like is separated from the self-adsorption portion.

  The non-adsorption portion described in the present invention is a portion in which the material itself does not adsorb a flat plate such as a semiconductor wafer (not an adsorption function layer) and keeps the separated state. This area has no functional layer.

  The surface of the mounting cushion of the present invention has a self-adsorption portion that detachably adsorbs a semiconductor wafer or the like and a non-adsorption portion that maintains a separated state without adsorbing the semiconductor wafer. Accordingly, the suction force by which the mounting cushion sucks the semiconductor wafer or the like is determined by the ratio of the area of the self-sucking portion and the area of the non-sucking portion in the region where the semiconductor wafer and the mounting cushion overlap. If the area of the overlapping area of the semiconductor wafer and the mounting cushion is S, the area of the self-adsorption part is SA, and the area of the non-adsorption part is SB, the ratio of the area of the self-adsorption part (this is the area of the self-adsorption part) The density is called SA / (SA + SB) = SA / S, and the adsorption force with which the mounting cushion adsorbs the semiconductor wafer or the like depends on SA / S. That is, if SA / S is large, the attracting force is large, and if SA / S is small, the attracting force is small. In order to increase the area density of the self-adsorption part, the area of the self-adsorption part may be increased and the area of the non-self-adsorption part may be reduced. Conversely, in order to reduce the area density of the self-adsorption part, the area of the self-adsorption part may be reduced and the area of the non-self-adsorption part may be increased.

  In the mounting cushion of the present invention, as described above, the suction force with which the mounting cushion sucks the semiconductor wafer is adjusted by the area density of the self-sucking portion. That is, by changing the area density of the self-adsorption portion according to the place of the placement cushion, the magnitude of the suction force of the placement cushion at that place can be changed. In particular, the area density of the self-adsorption part in the outer peripheral part of the mounting cushion in contact with the outer peripheral part of the semiconductor wafer is reduced, and the adsorption force for adsorbing the outer peripheral part of the semiconductor wafer is reduced, so that the central part from the outer peripheral part of the semiconductor wafer For example, in FIG. 3, the semiconductor wafer W can be easily separated from the mounting cushion 25 without being warped and taken out of the wafer mounting tray 1.

  Next, a method for changing the area density of the self-adsorption portion of the mounting cushion will be described.

  FIG. 11 is a schematic diagram in the case where the surface (that is, the suction surface) of the mounting cushion 51 made of a single material and having only the self-adsorption portion (that is, only the suction function layer) has an uneven shape. The mounting cushion 51 is formed of a single adsorbing material, for example, a foamed elastomeric polymer material, a foamed rubber polymer material, or a foamed urethane polymer material. (Alternatively, these composites may be used.) The surface of the mounting cushion 51 is in a concavo-convex state, and includes a convex portion 52 and a concave portion 53. It is desirable that the convex portion 52 is flat and the convex portion 52 of the entire mounting cushion has the same height. When the semiconductor wafer is placed on the mounting cushion 51 having such an uneven surface, the semiconductor wafer contacts the convex portion 52 of the mounting cushion. Next, when the semiconductor wafer is pressed, the convex portion 52 contracts. When the pressing force is removed, the contracted portion is completely or partially recovered. Since the convex part 52 has a self-adsorption function, the semiconductor wafer is adsorbed by the mounting cushion (the convex part 52). However, since the semiconductor wafer does not contact the concave portion 53, the semiconductor wafer is not attracted to the mounting cushion (the concave portion 53). Alternatively, there is a possibility that the concave portion 53 may be (lightly) contacted when the semiconductor wafer is pressed, but the degree of shrinkage of the concave portion 53 is considerably lower than the degree of shrinkage of the convex portion 52, so that the adsorption force of the semiconductor wafer is reduced. The concave portion 53 of the mounting cushion is separated from the semiconductor wafer when the pressing force is removed.

  Thus, by making the surface of the mounting cushion 51 uneven, it is possible to form a portion that adsorbs the semiconductor wafer and a portion that does not adsorb the semiconductor wafer. When the area of the convex portion 52 on the surface in a certain region is SV and the area of the concave portion 53 is SC, the area density of the (self) adsorption portion in this region is SV / (SV + SC). Since the semiconductor wafer is attracted to the mounting cushion 51 by the self-adsorptive force of the convex portion 52, the adsorption force by the mounting cushion of the semiconductor wafer in this region is changed by changing the area density SV / (SV + SC) of the attracting part. Can be changed. That is, by reducing the area of the convex portion 52 on the surface in a certain area and increasing the area of the concave portion 53, it is possible to reduce the suction force by the semiconductor wafer mounting cushion in this area.

  Thus, the area density of the self-adsorbing portion is increased by increasing the number of convex portions 52 in the central portion of the mounting cushion for mounting the central portion of the semiconductor wafer. On the other hand, the convex portion 52 of the outer peripheral portion of the mounting cushion for mounting the outer peripheral portion of the semiconductor wafer is reduced to reduce the area density of the self-adsorbing portion. In this way, the outer peripheral portion of the semiconductor wafer is reliably attracted to the mounting cushion, and when the semiconductor wafer is peeled off from the mounting cushion, the semiconductor wafer can be easily separated from the mounting cushion.

  Next, another example of changing the area density of the self-adsorption portion of the mounting cushion will be described.

  FIG. 12 shows an embodiment in the case of having a base material (non-adsorption portion) 62 made of a polymer material that is a material having no self-adsorption function and a self-adsorption portion made of a polymer material that is a material having a self-adsorption function. is there. After the surface of the base material 62 is formed in a concavo-convex shape, a self-adsorption portion is formed in the concave portion 63 of the base material. As a method for forming the self-adsorption part, a material having a self-adsorption function (polymer material) is applied to the surface of the uneven substrate, and the concave portion 63 of the base material is made of a material having a self-adsorption function (adsorption function layer). There is a method of filling, or a method of fitting (or embedding) a material (polymer material) having a self-adsorption function into the concave portion 63. Since the surface of the convex portion 64 (non-adsorption portion) of the base material having no self-adsorption function and the surface of the self-adsorption portion can be formed so as to be substantially flat, the semiconductor wafer is placed on the surface of the placement cushion 61. The semiconductor wafer can be brought into contact with the surface of the convex portion (non-adsorption portion) of the base material having no self-adsorption function and the surface of the self-adsorption portion.

  A base material (non-adsorbing portion) that does not have a self-adsorbing function is also made of a shrinkable material like the self-adsorbing portion. Next, when the semiconductor wafer is pressed, both the self-adsorption portion and the base material contract. When the pressing force is removed or weakened, the contracted part is fully or partially recovered. Since the self-adsorption part 63 has a self-adsorption function, the semiconductor wafer is adsorbed by the mounting cushion. However, since the portion where the semiconductor wafer is in contact with the non-adsorption portion 64 does not have a self-adsorption function, the semiconductor wafer is not adsorbed by the mounting cushion (the base material portion thereof).

  As described above, by forming the self-adsorption part having the self-adsorption function and the non-adsorption part not having the self-adsorption function on the surface of the mounting cushion, it is possible to form the part that adsorbs the semiconductor wafer and the part that does not adsorb the semiconductor wafer. If the area of the self-adsorption part in a certain region is SS and the area of the non-adsorption part is SN, the area density of the self-adsorption part in this region is SS / (SS + SN). If SS / (SS + SN) is large, the mounting force that adsorbs the semiconductor wafer or the like is large. If SS / (SS + SN) is small, the adsorbing force that the mounting cushion adsorbs the semiconductor wafer or the like is small. Thus, by changing the ratio of the area of the self-adsorption part and the area of the non-adsorption part, the area density of the self-adsorption part can be adjusted.

  Therefore, when the present invention is used, by changing the area density of the self-adsorption portion depending on the location, the adsorption force of the mounting cushion that adsorbs the semiconductor wafer can be easily changed depending on the location in the mounting cushion. In the mounting cushion of this invention, the self-adsorption part of the center part of the mounting cushion which mounts the center part of a semiconductor wafer is increased, and the area density of a self-adsorption part is enlarged. On the other hand, the area density of the self-adsorbing portion is reduced by reducing the number of self-adsorbing portions on the outer peripheral portion of the mounting cushion for mounting the outer peripheral portion of the semiconductor wafer. If it does in this way, the outer peripheral part of a semiconductor wafer will become easy to leave | separate from a mounting cushion.

  As another embodiment in which the surface of the mounting cushion as shown in FIG. 12 is formed with a self-adsorbing portion and a non-adsorbing portion, contrary to FIG. ), The self-adsorption portion and the non-adsorption portion can be formed on the surface of the mounting cushion by filling the concave portion with a non-adsorption portion having no self-adsorption function.

  In addition, the self-adsorption part and the non-adsorption part are formed on the surface of the mounting cushion by alternately forming (adjacent) a material having a self-adsorption function and a material not having a self-adsorption function on the surface of a flat substrate. it can. For example, a material having a self-adsorption function and a material having no self-adsorption function are attached to the surface of a flat substrate, or a material having a self-adsorption function and a material having no self-adsorption function are adhered to a flat substrate. The self-adsorbing portion and the non-adsorbing portion can be alternately (adjacently) formed on the surface of the mounting cushion by applying to the surface.

  In FIG. 3, as described above, the self-adsorbing portion has a cushioning property and hardly exerts a chemical adverse effect on the surroundings. For example, the self-adsorbing portion is highly foamed rubber type such as foamed acrylic latex made of an acrylate copolymer. Of the many bubbles formed in the self-adsorbing portion, the bubbles that open to the outside air each function as a fine sucker, which is formed of a molecular material, a foamed elastomer-based polymer material, a foamed urethane-based polymer material, or the like. Therefore, the entire surface of the self-adsorbing part exposed is an aggregate layer of the fine sucker, and the semiconductor wafer W is adsorbed and fixed to the self-adsorbing part by pressing the fine sucker against the semiconductor wafer W as the adsorbing partner. It becomes a state. The bubble may be either an open cell or a closed cell, and it is desirable that the average diameter of the bubble is about 10 μm or more and about 50 μm or less.

  As clearly shown in FIG. 4, in this embodiment, a region 25 </ b> A having a large area density of the self-adsorption portion is a central portion of the mounting cushion 25, that is, a disk shape having a diameter smaller than the diameter of the semiconductor wafer W. The region 25B having a small area density of the self-adsorption portion surrounds the entire periphery. W ′ indicated by a two-dot chain line in FIG. 4 is an outer edge position of the semiconductor wafer W when the semiconductor wafer W is placed on the placement cushion 25, and is closer to the outer edge of the region 25B having a smaller area density of the self-adsorption portion. Is formed larger than the semiconductor wafer W, and the outer edge position W ′ of the semiconductor wafer W is located in the region 25B where the area density of the self-adsorption portion is small.

  As the material of the non-adsorbing part, for example, a foamed polymer material such as urethane foam or an elastomeric polymer material having a cushioning property comparable to that of the self-adsorbing part and having no self-adsorptive property can be used. . The mounting cushion 25 shown in FIG. 3 has a large area density of the self-adsorbing portion in the central region 25A of the mounting cushion 25 to which the central portion of the semiconductor wafer W is attracted. The area density of the self-adsorption part in the outer peripheral part region 25B of the mounting cushion 25 to which is adsorbed is small. As a result, when the semiconductor wafer W is pressed against the mounting cushion 25, the reaction force from the mounting cushion 25 acts uniformly on the entire semiconductor wafer W, and the semiconductor wafer W can be safely stored without distortion. it can.

  1 and 5 show a state where two wafer mounting trays 1 are separated and a state where they are overlapped. When the two wafer mounting trays 1 are separated, the semiconductor wafer W is actually held by the mounting cushion 25 as shown in FIG. For the sake of clarity, the semiconductor wafer W is illustrated separately in FIG.

  An elastic wafer pressing cushion sheet 15 (hereinafter referred to as “pressing cushion 15” for pressing the semiconductor wafer W against the mounting cushion 25 of the lower wafer mounting tray 1 is provided on the back surface 14 of the wafer mounting tray 1. Is abbreviated as “)”. The pressing cushion 15 of this embodiment, like the mounting cushion 25, has a disk shape that can press a predetermined region or substantially the entire surface of the semiconductor wafer W with a material that does not have a chemical adverse effect on the semiconductor wafer W. Is formed.

  Specifically, an elastic polymer sheet 15A made of, for example, foamed urethane or urethane resin that functions as an elastic cushion in contact with the state pressed against the surface of the semiconductor wafer W, and the back surface (lower surface) of the wafer loading tray 1 ) And a base material sheet 15B made of a material such as PET (polyethylene terephthalate) attached to 14 is laminated and integrated. The contact surface with the semiconductor wafer W is preferably formed on a slightly uneven surface so as not to be attracted to the semiconductor wafer W. The attachment of the pressing cushion 15 to the wafer mounting tray 1 is the same as the mounting of the mounting cushion 25. That is, in this embodiment, the pressing cushion 15 is bonded to the back surface 14 of the wafer loading tray 1, but a frame body, a pin, or the like that is detachable from the bottom surface 13 of the wafer loading tray 1 can be used. By forming a self-adsorption layer including an adsorption portion, the pressing cushion 15 can be configured to be detachable from the wafer mounting tray 1 and can be easily cleaned or replaced.

  In the wafer storage container with a cushion sheet of the embodiment configured as described above, when the semiconductor wafer W is transported and stored, the semiconductor wafer W is placed with a cushioning property as shown in FIG. In an inner space formed between the wafer mounting tray 1 and the wafer mounting tray 1 stacked adjacent to the upper side thereof in a state of being elastically sandwiched between the cushion 25 and the pressing cushion 15. Stored safely.

  And even if the wafer mounting tray 1 that has been overlapped is separated, the semiconductor wafer W is in a state of being adsorbed by the self-adsorption portion of the mounting cushion 25 as shown in FIG. Even when the wafer mounting tray 1 is tilted during the separation operation of the wafer mounting tray 1 or the inspection of the semiconductor wafer W, the mounting cushion 25 does not slide down from the wafer mounting tray 1 and There is no possibility that the semiconductor wafer W slides down from the mounting cushion 25. Further, since the semiconductor wafer W is in a state of being adsorbed and fixed to the upper surface of the mounting cushion 25, the semiconductor wafer W is always kept flat without warping, so that the semiconductor wafer W warps from a flat state. Occurrence of a phenomenon that breaks by repeating the state can be prevented in advance.

  When removing the semiconductor wafer W from the wafer mounting tray 1, the suction force of the mounting cushion that sucks the outer peripheral portion of the semiconductor wafer W is the suction force of the mounting cushion that sucks the central portion of the semiconductor wafer W. Therefore, if a force that separates from the mounting cushion 25 is applied to the entire semiconductor wafer W (or at least a wide range including the outer edge portion), the outer peripheral portion of the mounting cushion 25 is detached from the outer peripheral portion of the semiconductor wafer W. Then, air enters the fine suction cups of the self-adsorptive part sequentially from the gap formed between the outer edge parts of the semiconductor wafer W and the mounting cushion 25, and the adsorbing force of the self-adsorptive part disappears. It can be easily pulled away from the mounting cushion 25 and taken out of the wafer mounting tray 1.

  FIG. 6 shows a state in which the transfer chuck 30 for removing the semiconductor wafer W from the wafer mounting tray 1 is adsorbed to the upper surface which is the open surface of the semiconductor wafer W. A semiconductor that is adsorbed in a region where the area density of the self-adsorption portion of the mounting cushion 25 is small because all or part of the region where the area density is small is located inside the outer edge of the conveyance chuck 30. The outer edge portion of the wafer W is lifted by the transfer chuck 30, and the semiconductor wafer W can be easily removed from the mounting cushion 25 as described above. That is, when the force for adsorbing the semiconductor wafer by the transfer chuck 30 is constant, once the semiconductor wafer W is peeled from the placement cushion 25, the overall force for the placement cushion 25 to attract the semiconductor wafer becomes weak. W can be easily removed from the mounting cushion 25. In addition, as the conveyance chuck 30, for example, a so-called Bernoulli hand that sucks the object to be conveyed in a non-contact state using a negative pressure generated by flowing an air flow between the object and the object to be conveyed, or a static adsorption force. A so-called electrostatic hand or the like can be used.

  In addition, this invention is not limited to the said embodiment, For example, as FIG. 7 shows, the structure of the mounting cushion 25 is on the base material sheet 25C for the mounting cushion 25 whole, A sheet 25B having a small area density of the self-adsorptive part is attached to the outer peripheral part of the mounting cushion 25, and an area density of the base sheet 25A 'for the sheet 25A having a large area density of the self-adsorptive part and the self-adsorptive part is disposed on the inside. A large sheet 25A may be provided separately. Also in this case, it is desirable that the sheet 25A and the sheet 25B have the same height. Further, as shown in FIG. 8, the sheet 25B having a small area density of the self-adsorption portion that is extremely thin (for example, about 10 to 20 micrometers) is placed on the surface of the outer edge portion of the sheet 25A having a large area density of the self-adsorption portion. Lamination and integration may be performed in the state of being placed. In this case, the heights of the sheet 25A and the sheet 25B are slightly different, but the sheet 25B is very thin and does not affect the size of the area density of the self-adsorption portion. If the influence is to a certain extent, the area density of the self-adsorptive portions of each other may be adjusted. That is, the area density of the self-adsorptive portion in the sheet 25B may be made smaller than when the sheets 25A and 25B are flat. Alternatively, as shown in FIG. 9, a part of the surface of the sheet 25A having a large self-adsorbing portion area density is not adsorbed by, for example, subjecting the surface in the vicinity of the outer edge portion of the sheet 25A having a large area density of the self-adsorbing portion. The sheet 25B having a small self-adsorption portion area density may be formed by processing the portion. Such a concavo-convex surface can be formed by means such as so-called branding that presses a heated metal plate or the like against a resin material.

  Further, as a formation region of the sheet 25B having a small self-adsorption portion area density, when the semiconductor wafer W is placed on the mounting cushion 25, the sheet 25B is at least at a position facing a part or all of the outer edge portion of the semiconductor wafer W. When the semiconductor wafer W is peeled off, air can be sent from the outer edge side to the fine suction cup of the mounting cushion 25 when the semiconductor wafer W is peeled off, and the semiconductor wafer W can be removed from the self-adsorbing portion without warping. The relationship with the conveyance chuck 30 is the same, and a part or all of the region 25 </ b> B having a small area density of the self-adsorbing portion may be formed at a position inside the outer edge of the conveyance chuck 30.

  Next, an example of the arrangement of the self-adsorption part and the non-adsorption part of the mounting cushion of the present invention will be described.

  FIG. 13 is a diagram for explaining the state of the arrangement of the self-adsorption part and the non-adsorption part when the entire surface has a uniform adsorption force. FIG. 13A shows a self-adsorptive portion arranged on the surface of the mounting cushion 71 in a cross like a grid. Lines or black spots 72 are self-adsorbing portions, and white portions 73 are non-adsorbing portions. The semiconductor wafer is disposed on the surface of the mounting cushion 71. Since the area density of the self-adsorption portion is the same everywhere on the surface of the mounting cushion 71, the suction force that the mounting cushion 71 absorbs the semiconductor wafer is also anywhere on the semiconductor wafer. Almost uniform. FIG. 13B shows a self-adsorptive portion arranged in a spot shape on the surface of the mounting cushion 71 at substantially the same density. Black dots 72 are self-adsorbing portions, and white portions 73 are non-adsorbing portions. Also in this case, since the area density of the self-adsorbing portion is the same everywhere on the surface of the mounting cushion, the suction force by which the mounting cushion 71 attracts the semiconductor wafer is almost uniform everywhere on the semiconductor wafer. As can be seen from these arrangements, by changing the line spacing between the self-adsorption parts on the line, or by changing the interval between the spot-shaped self-adsorption parts (that is, changing the density of the self-adsorption parts) The area density of the self-adsorption part can be changed.

  FIG. 14 is a diagram showing the arrangement of the self-adsorption part and the non-adsorption part on the surface of the mounting cushion according to the embodiment of the present invention. In FIG. 14A, the self-adsorbing portions 82 are radially arranged on the surface of the mounting cushion 81. The white part 83 is a non-adsorption part. In FIG. 14B, the self-adsorbing portions 82 are spirally arranged on the surface of the mounting cushion 81. 14A and 14B, the self-adsorbing portion 82 gathers at the center of the surface of the mounting cushion 81, and the self-adsorbing portion 82 is sparse outside the surface of the mounting cushion 81. Therefore, the area density of the self-adsorbing portion is the largest near the center of the surface of the mounting cushion 81 and decreases as it goes outside the surface of the mounting cushion 81. Since the semiconductor wafer is disposed on the surface of the mounting cushion 81 (the center of the semiconductor wafer is mounted substantially at the center of the mounting cushion 81), the adsorption force with which the mounting cushion 81 adsorbs the semiconductor wafer is the semiconductor. It is large near the center of the wafer and decreases as it goes outside the semiconductor wafer. For this reason, when the semiconductor wafer adsorbed by the mounting cushion 81 is separated from the mounting cushion 81, the semiconductor wafer can be gradually separated from the mounting cushion 81 toward the center from the outside of the semiconductor wafer. Even if the thickness is reduced to a micrometer or less, the semiconductor wafer can be safely and easily taken out without being damaged.

  FIG. 15 is a diagram showing an arrangement of self-adsorbing portions and non-adsorbing portions on the surface of the mounting cushion according to another embodiment of the present invention. Similar to the case of FIG. 13B, self-adsorption portions 92 are arranged in a spot shape on the surface of the mounting cushion 91. Black dots 92 are self-adsorbing portions, and white portions 93 are non-adsorbing portions. The central portion 94 has a large area density of the self-adsorbing portion, and the peripheral portion 95 has a small area density of the self-adsorbing portion. (The circular line inside the mounting cushion 91 is drawn so that the boundary between the two can be clearly understood.) With such an arrangement, the adsorption force for adsorbing the outer periphery of the semiconductor wafer can be reduced. . For this reason, when the semiconductor wafer adsorbed by the mounting cushion is separated from the mounting cushion, it can be gradually separated from the mounting cushion from the outside to the center of the semiconductor wafer, even if the semiconductor wafer is 100 microns or less. Even if the thickness becomes extremely thin, the semiconductor wafer can be safely and easily taken out without being damaged.

  As an application of the arrangement of the self-adsorption part and the non-adsorption part on the surface of the mounting cushion shown in FIG. 15, the mounting cushion that adsorbs the outer peripheral part of the semiconductor wafer from the central part of the mounting cushion that adsorbs the central part of the semiconductor wafer. There is a method of gradually decreasing the area density of the self-adsorption portion toward the outer peripheral portion. In this case, the semiconductor wafer is securely and securely adsorbed to the mounting cushion, and when the semiconductor wafer is removed from the mounting cushion, the force for adsorbing the semiconductor wafer gradually increases from the outer periphery of the semiconductor wafer. Since the semiconductor wafer is moved away from the mounting cushion toward the center of the semiconductor wafer, the semiconductor wafer can be taken out extremely safely and easily without being damaged.

  Further, as shown in FIG. 16, the pressing cushion 15 is configured such that only the outer edge portion thereof is fixed to the wafer mounting tray 1 and the other portion is floated from the back surface 14 of the wafer mounting tray 1. Good. In this way, the semiconductor wafer W can be stored in a state where an appropriate cushioning property is applied regardless of the thickness of the semiconductor wafer W. The pressing cushion 15 can also be formed of a single layer elastic polymer sheet or the like. In this case as well, the contact surface of the pressing cushion 15 with respect to the semiconductor wafer W is preferably formed on a slightly uneven surface so as not to be attracted to the semiconductor wafer W.

  In the above, some arrangements of the self-adsorption part and the non-adsorption part on the surface of the mounting cushion according to the present invention have been described. However, these are only examples, and the other arrangements are not limited thereto. It goes without saying that it is included in the invention.

  An object of the present invention is to vary the area density of the self-adsorption portion on the surface of the mounting cushion, and to change the adsorption force with which the mounting cushion adsorbs a semiconductor wafer or the like depending on the location. In particular, the area density of the self-adsorption portion near the center of the mounting cushion surface is increased, and the adsorption force for adsorbing the semiconductor wafer is increased near the center to reliably adsorb the semiconductor wafer. Furthermore, the area density of the self-adsorption part in the outer peripheral part of the mounting cushion surface is reduced, and the adsorption force for adsorbing the semiconductor wafer is reduced in the outer peripheral part. As a result, the semiconductor wafer is firmly adsorbed to the mounting cushion including the outer peripheral portion thereof, but it becomes easy to pull the semiconductor wafer away from the mounting cushion, even if the semiconductor wafer becomes extremely thin of 100 microns or less. However, the semiconductor wafer can be taken out safely and easily without being damaged.

  In the description of the present invention described above, the flat plate such as the mounting cushion and the semiconductor wafer has been described as having a circular shape. However, the present invention is not limited to a circular shape, and may be applicable to a rectangular shape, a rectangular shape such as a square shape, or the like. Needless to say. In addition, the present invention can be applied not only to semiconductor wafers but also in the field using display devices, solar cells, and other thin substrates. In addition, it goes without saying that the contents not described in the description of the respective examples and embodiments described above can be applied as long as there is no contradiction between them.

The present invention can be applied to the semiconductor industry using a wafer container used for transporting or storing semiconductor wafers.

FIG. 1 is a side cross-sectional view showing a state where two wafer mounting trays stacked in the embodiment of the present invention are separated. FIG. 2 is a perspective view of the overall configuration of the wafer storage container with a wafer mounting cushion sheet according to the present invention, showing a part of the state in which a large number of wafer mounting trays are stacked. FIG. 3 is a side cross-sectional view of a state in which a semiconductor wafer is placed on one of the wafer placement trays with a wafer placement cushion sheet according to the present invention. FIG. 4 is a perspective view of the wafer mounting cushion sheet according to the present invention and the semiconductor wafer separated from each other. FIG. 5 is a side sectional view showing a state in which two wafer mounting trays with a wafer mounting cushion sheet according to the present invention are overlaid. FIG. 6 is a side cross-sectional view showing a state in which a semiconductor wafer is taken out from the wafer placement tray with a wafer placement cushion sheet according to the present invention by a transfer chuck. FIG. 7 is a side cross-sectional view of a first modified example having a layer structure with a wafer mounting cushion sheet of the present invention. FIG. 8 is a side cross-sectional view of a second modified example having a layer structure of the wafer mounting cushion sheet of the present invention. FIG. 9 is a side cross-sectional view of a third modified example that is a layer structure of the wafer mounting cushion sheet of the present invention. FIG. 10 is a view showing the structure of the adsorption function layer in the wafer mounting cushion sheet of the present invention. FIG. 11 is a diagram showing a method for varying the area density of the self-adsorption portion in the present invention. FIG. 12 is a diagram showing another method for varying the area density of the self-adsorption part in the present invention. FIG. 13 is an explanatory diagram of an arrangement state of the self-adsorption part and the non-adsorption part. FIG. 14 is a diagram showing the arrangement of the self-adsorption part and the non-adsorption part on the surface of the mounting cushion according to the embodiment of the present invention. FIG. 15 is a diagram showing an arrangement of self-adsorbing portions and non-adsorbing portions on the surface of the mounting cushion according to another embodiment of the present invention. FIG. 16 is a side cross-sectional view of a state where two wafer mounting trays to which a modified example of the wafer pressing cushion sheet of the present invention is applied are overlapped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wafer mounting tray 13 Bottom surface 15 Pressing cushion (wafer pressing cushion sheet)
25 Mounting cushion (wafer mounting cushion sheet)
25A Area with high area density of self-adsorption part 25B Area with low area density of self-adsorption part 30 Transfer chuck W Semiconductor wafer W 'Outer edge position of semiconductor wafer

Claims (13)

A plurality of wafer placement trays for placing and holding semiconductor wafers one by one are overlaid, and the semiconductor wafers placed on the respective wafer placement trays are overlaid adjacent to the wafer placement tray. The wafer mounting cushion sheet is disposed in an inner space formed between the wafer mounting trays and an elastic wafer mounting cushion sheet is disposed at the semiconductor wafer mounting position on the upper surface of each wafer mounting tray. In a wafer storage container with a wafer mounting cushion sheet,
On the surface of the wafer mounting cushion sheet, a self-adsorption portion that detachably adsorbs the semiconductor wafer and a non-adsorption portion that maintains the separated state without adsorbing the semiconductor wafer are formed. A wafer with a wafer mounting cushion sheet, characterized in that the adsorption force by which the sheet adsorbs the semiconductor wafer is adjusted by the area density of the self-adsorption part determined from the area of the self-adsorption part and the area of the non-adsorption part Storage container.   2. The wafer storage container with a wafer mounting cushion sheet according to claim 1, wherein the area density of the self-adsorption portion is changed depending on the location of the wafer mounting cushion sheet.   The area density of the self-adsorption part of the outer periphery of the wafer mounting cushion sheet that adsorbs the outer peripheral part of the semiconductor wafer is equal to that of the self-adsorption part of the central part of the wafer mounting cushion sheet that adsorbs the central part of the semiconductor wafer. The wafer storage container with a wafer mounting cushion sheet according to claim 2, wherein the wafer storage container has a smaller area density.   The wafer having an area density of a self-adsorption portion of the wafer mounting cushion that adsorbs the semiconductor wafer adsorbs an outer peripheral portion of the semiconductor wafer from a central portion of the wafer mounting cushion sheet that adsorbs a central portion of the semiconductor wafer. The wafer storage container with a wafer mounting cushion sheet according to claim 3, wherein the wafer storage container is reduced toward an outer peripheral portion of the mounting cushion sheet.   The wafer mounting cushion sheet according to any one of claims 1 to 4, wherein the non-adsorptive part is formed by laminating a non-adsorptive sheet on the surface of the self-adsorptive part. Wafer storage container.   5. The wafer mounting cushion according to claim 1, wherein the non-adsorption portion is formed by processing a part of the surface of the self-adsorption portion into a non-adsorption property. Wafer storage container with sheet.   The wafer storage container with a wafer mounting cushion sheet according to claim 6, wherein the non-adsorption portion is formed by subjecting a part of the surface of the self-adsorption portion to uneven processing.   The self-adsorption part is formed by a large number of fine suction cups, and the fine suction cup and the semiconductor wafer are in an adsorbed and fixed state by pressing the fine suction cups against the semiconductor wafer. The wafer storage container with a wafer mounting cushion sheet according to any one of 1 to 7.   The self-adsorbing part is formed of a foamed elastomeric polymer material, a foamed rubber-based polymer material, a foamed urethane-based polymer material, or a composite material thereof having elasticity. A wafer storage container with a wafer mounting cushion sheet according to any one of the above.   The wafer storage container with a wafer mounting cushion sheet according to claim 9, wherein the foamed rubber-based polymer material is a foamed acrylic latex made of an acrylate copolymer.   A part or the whole of the area where the area density of the self-adsorption portion is small is formed at a position inside the outer edge of the transfer chuck that is adsorbed to the semiconductor wafer when the semiconductor wafer is detached from the wafer mounting cushion sheet. The wafer storage container with a wafer mounting cushion sheet according to any one of claims 1 to 10, wherein   The wafer storage container with a wafer mounting cushion sheet according to any one of claims 1 to 11, wherein the wafer mounting cushion sheet is detachably attached to the wafer mounting tray.   The elastic wafer pressing cushion sheet for pressing the semiconductor wafer against the wafer mounting cushion sheet is disposed on the back side of the wafer mounting tray. A wafer storage container with a wafer mounting cushion sheet according to any one of the items.

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