US3850296A

US3850296A - Device and method for accommodating semiconductor wafers

Info

Publication number: US3850296A
Application number: US00273030A
Authority: US
Inventors: T Hirata; S Ohga; T Kaya
Original assignee: Shin Etsu Handotai Co Ltd
Current assignee: Shin Etsu Handotai Co Ltd
Priority date: 1971-07-21
Filing date: 1972-07-19
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

The device includes a block-type holder for storing and transporting circular semi-conductor wafer disks, a covering element cooperating with the holder to enclose the wafers and having a top wall and side walls, and a pad of compressed foam material, sealed in a plastic bag and maintained compressed by atmospheric pressure on the plastic bag, positioned in the covering element above the wafers and confined by the convering element''s side walls. The holder is formed with at least one generally V-shaped longitudinal groove whose upwardly diverging walls are formed with longitudinally spaced, substantially parallel transverse V-grooves, corresponding transverse grooves in the two walls lying in the same transverse plane to receive respective wafers engaging surfaces of the transverse grooves at the wafer edges only, with the wafers in upright position. The covering element top wall is formed with a slit to receive a piercing tool to pierce the sealed plastic bag for expansion of the foam material pad into engagement with the wafers and with the top wall. The wafers may be supported to extend vertically or may be supported to extend at a slight inclination to the vertical. The wafers may be positioned in the holder and removed therefrom by a so-called air pincette, which is a suction tube in which suction may be successively applied or released at a work engaging end thereof.

Description

States Hirata et al.

[ DEVICE AND METHOD FOR ACCOMMODATING SEMICONDUCTOR WAFERS [75] Inventors: Teruhito Hirata; Shoichiro Ohga,

both of Annka; Tomoji Kaya, Tokorozawa, all of Japan [73] Assignee: Shin-Etsu Handotai Co., Ltd.,

Tokyo, Japan [22] Filed: July 19, 1972 [21] Appl. No.: 273,030

[30] Foreign Application Priority Data July 21, 1971 Japan 46-54321 Sept. 6, 1971 Japan 46-68709 [52] US. Cl 206/334, 206/73, 206/454,

[51] Int. Cl B6511 85/30, B65d 85/62 [58] Field of Search 206/65 F, 72, 73, 62 R,

[56] References Cited UNITED STATES PATENTS 2,829,767 4/1958 Scripture 206/73 3,061,089 10/1962 Higgins 206/46 FC 3,180,697 4/1965 Mulch 220/41 3,275,329 9/1966 Lieberman et a1 206/72 3,306,462 2/1967 Da Cruz 206/72 3,307,318 3/1967 Bauman 206/46 FC 3,400,809 9/1968 Puente 206/62 R 3,463,301 8/1969 Speelman 3,467,242 9/1969 De'Rousse 3,534,862 10/1970 Shambelan 206/1 R Primary ExaminerWilliam T. Dixson, Jr. Attorney, Agent, or F irm-McGlew and Tuttle [5 7 ABSTRACT The device includes a block-type holder for storing and transporting circular semi-conductor wafer disks, a covering element cooperating with the holder to enclose the wafers and having a top wall and side walls, and a pad of compressed foam material, sealed in a plastic bag and maintained compressed by atmospheric pressure on the plastic bag, positioned in the covering element above the wafers and confined by the convering elements side walls. The holder is formed with at least one generally V-shaped longitudinal groove whose upwardly diverging walls are formed with longitudinally spaced, substantially parallel transverse V-grooves, corresponding transverse grooves in the two walls lying in the same transverse plane to receive respective wafers engaging surfaces of the transverse grooves at the wafer edges only, with the wafers in upright position. The'covering element top wall is formed with a slit to receive a piercing tool to pierce the sealed plastic bag for expansion of the foam material pad into engagement with the wafers and with the top wall. The wafers may be supported to extend vertically or may be supported to extend at a slight inclination to the vertical. The wafers may be positioned in the holder and removed therefrom by a so-called air pincette, which is a suction tube in which suction may be successively applied or released at a work engaging end thereof.

12 Claims, 8 Drawing Figures DEVICE AND METHOD FOR ACCOODATING SEMICONDUCTOR WAFERS SUMMARY OF THE INVENTION This invention relates to containers for a plurality of semiconductor wafers to be retained, stored and transported in a safe manner and to a method of performing same.

BACKGROUND OF THE INVENTION AND PRIOR ART The occurrence of injuries to semiconductor wafers during storage and transportation should be avoided by all means. Recently, with the provision of semiconductor devices having a high standard of properties and complicated circuits, such as large-scale integrated circuits, as the result of improvements in qualities of semiconductor materials, the occurrence of dirt and bruises on the surfaces of the wafers to be used in making semiconductor devices have been regarded as a serious problem, for injured wafers would result in the production of defective semiconductor devices, or else would have to be discarded.

One of the causes for dirt or bruises on semiconductor wafers was supposed to lie in the manner of keeping the semiconductor wafers in a container or supporter and specifically the form, construction and arrangement of parts of the container or supporter. Therefore, several proposalshave been made as to improvements in the device. For example, US. Pat. Nos. 3,469,686 and 3,482,682 describe trays having a plurality of wells wherein each well is diametrally compatible to a semiconductor wafer for retaining the same therein. It has also been proposed to accommodate semiconductor wafers in a box-type container wherein a row or rows of grooves are provided in a block, each groove being semicircular in its cross section to fit the circumferential shape of the wafers, with a number of cuts at right angles to the grooves in the bottom and side walls, in parallel with each other, for holding the wafers upright.

According to the retaining trays mentioned above, flat semiconductor wafers are disposed in a horizontal position, so that they may be moved, advantageously, by an air pincette, which is a tool of tube-type used in drawing and releasing things to and from its end by controlling pressures therein, while the wafers, disadvantageously, tend to have their surfaces become dirty or bruised, and yet the trays are unfit to accommodate a great number of the wafers on one tray. The other conventional device also referred to above is capable of keeping the wafers with their surfaces less liable to get dirty, because the wafers are disposed upright. However, it is hardly practical to use the air pincette, because both ends of the retaining groove are closed. Thus, it is not easy to safely dispose and move the wafers. Further, in this device shock-absorbers of soft plastic foam materials are used for the purpose of protecting the wafers from, possibilities of being broken when they shake during transportation. But such foamy materials are liable to be contaminated with catalysts used or impurities from machinery during their manufacturing processes, and they themselves are apt to adsorb dirt and, as a result their use as shock-absorbers has often caused contamination of the wafers. Still further, since the voluminous shock-absorber is exces-.

Ill

of wafers and the lid, the wafers sometimes become bruised or broken. As such, the known devices for the handling, shipment and storage of semiconductor wafers have not been very effective and useful.

OBJECTS OF THE INVENTION It is the primary object of the present invention to provide a container and a method for keeping a number of semiconductor wafers in such manner that each wafer is disposed free from contact with any foreign surfaces.

It is also an object of the present invention to provide a container wherein a number of semiconductor wafers are supported and protected against impact, friction, etc. from, outside so that they may be free from injury.

It is a further object of the invention to provide a device whereby semiconductor wafers are, one by one, put into the container to be held substantially upright, by means of the previously described air pincette, without injuring their surfaces and may be moved out of the container in like manner and conditions.

With the above and other objects in view, the invention resides in the novel features of form, construction, combination and arrangements of parts of the device for packing semiconductor wafers presently described and pointed out in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a perspective view of a typical device of the present invention, showing a plurality of semiconductor wafers held in a holder and a hood removably disposed over the holder;

FIG. 2 is a perspective view of a pad stuffed with foam material, compressed in vacuum within a covering of synthetic resin films;

FIG. 3 is a perspective view, showing the pad of FIG. 2 in which the foam material has been expanded by air introduced thereinto;

FIG. 4 is a cross-sectional view, showing the semiconductor wafers disposed in a holder, the compressed pad disposed immediately over the rows of wafers, and a hood tightly fixed to the holder;

FIG. 5 is a sectional view showing another embodiment in which the pad is disposed immediately under theupper wall of the hood;

FIG. 6 is a sectional view, similar to FIG. 4 or 5, with the pad fully expanded in the enclosure; and

FIGS. 7 and 8 are perspective views, showing modified forms of embodiments of the invention.

DESCRIPTION OF THE INVENTION The device of the invention is effectively and usefully applicable for accommodating a plurality of semiconductor wafers that have highly polished surfaces or surfaces treated by epitaxial growth and, therefore, must be kept free from injury and contamination. According to the device of the invention, the semiconductor wafers are retained in a groove or grooves provided in a block-type holder, and over the wafers thus retained and enclosed with an element to cover the holder is disposed a pad of plastic film containing foam material held in compressed condition. More specifically, the device comprises a block-type holder supporting a plurality of semiconductor wafers upstanding in parallel in a row or rows, a covering element or hood removably disposed over the holder and a pad of plastic film, stuffed with foam material in vacuum and compressed condition, disposed in the space within the hood. In the upper part of the hood, there is provided a small slit through which a knife or the like is thrust into the pad so that, air being admitted, the pad is immediately expanded to fully occupy the space within the hood.

The pad used herein is made of continuous cellular materials, such as, polyurethane, polyolefin, polystyrene, and silicone rubber, wrapped with plastic films made, for example, from polyethylene. The foam material is vacuumpacked or packed by depression in vacuum condition, so that when air is introduced by a breach in the wrapping film, the foam material will expand into its original condition.

DESCRIPTION OF SPECIFIC EMBODIMENTS More detailed descriptions of the device and method of the invention will be given hereunder with reference to the accompanying drawings.

In FIG. 1, 1 is a block-type holder having two rows of grooves, forming W-shape in end elevation, and, on the slanting and confronting side wall 2 of each groove, V-shape cuts 3 are provided in parallel at certain angles with respect to the longitudinal groove. The block-type holder may be a single block with a V-shape groove or a series of such blocks arranged side by side. The V- shape cuts 3 are arranged so that each confronting pair thereof hold upstanding a semiconductor wafer designated by W. The cuts 3 are provided in the walls 2 in an orientation such that the wafers W retained thereby have an angle to the vertical of substantially or, alternatively, the cuts 3 extend exactly vertical and the holder per se may be inclined at substantially 5 to the horizontal. Thus, the semiconductor wafers can be supported in more stable conditions than when they are held exactly upright. The holder of the present invention is usually formed by injection-molding of synthetic resins, such as, polyethylene, polypropylene, and polyvinyl chloride. It is preferred to mold the holder hollow in order to reduce its weight and minimize the cost of the material to be used.

Further in FIG. 1, the covering element or hood 4 is box-shaped and has a pair of end walls 5 and a pair of side walls 6, each pair of walls being different in height and length from the other and, so as to cover the entire part of the holder, the

walls

5 and 6 are designed to be adapted for coming into complete intimate contact with

parts

8 and 7, respectively, on the holder. When the holder 1 and the cover hood 4 are closely interfitted, a clasp 9, provided horizontally movable on part 8 of the holder, is fastened to its counterpart 10 on the cover wall 5, thereby tightly holding the holder 1 and the cover hood 4 together. It should be noted that this clasping device is not an essential of the invention. An adhesive tape or the like can be applied instead. The shape of the cover member is not limited to what is shown in FIG. I. It may be shaped like an ordinary box with the shorter and longer walls (5 and 6) having the same height. Accordingly, in this case, the receiving parts (8 and 7) on the holder must be located on the same level.

About at the center of the upper side 12 of the covering member 4, there is cut a slit 1], through which a knife is thrust inside to pierce a pad of plastic films, containing foam material, disposed over the semicon ductor wafers W on the holder 1 and under the lid part 12. The covering member 4 is usually formed of the same synthetic resin material as the holder 1 or it may be made of cardboard.

FIGS. 2 and 3 show the foam pads in compressed and expanded conditions, respectively. The pad is prepared, for example, by packing comparatively soft plastic foam material 14 in a plastic film 15. When a part of the cover film 15 is broken with a pin or a knife, air enters into the compressed pad and the foam material 14 gradually regains its former resilience. The foams 14 are selected from resin foams such as polyurethane foams or silicone rubber foams. The foam pad 13 is prepared by packing in vacuo the foams 14 in a plastic film, or by packing the compressed foams in a plastic film. In packing the foam, the size of the plastic film must be large enough to enclose the entire foam mate .rial 14 in its original expanded condition. The wrinkles of the plastic film are designated by 16 in FIG. 2. If the foams 14 are too resilient, they may impose an excessive pressure on the wafers W so that, when the plastic film 15, covering the foam pad 14, is broken for the purpose of having the foams expand, then the wafers may be broken. Thus, the foams must have a proper degree of resilience. The size of the foam pad 13 should, horizontally, be such as approximately fits the inside area of the covering hood 4, so that the compressed foams may expand only upward and downward.

Now, the method for accommodating the wafers will be described with reference to FIGS. 4, 5, and 6. To practice the method of the invention, a number of semiconductor wafers are first placed in the grooves, one by one, by means of an air pincette. Then, as shown in FIG. 4, above the wafers W there is placed the foam pad 13 and, subsequently, the covering element 4 is closely fixed to the holder 1. Or, as shown in FIG. 5, the pad 13 is first seated on the inside of the lid part 12 of the covering element 4, and then the covering element is placed over the holder 1, so that the holder 1 and the cover 4 are fastened to each other. A knife or a pin is then thrust through the slit 11 provided in the lid part 12, so as to pierce a part of the plastic film 15, whereupon air is introduced into the pad 13 to make the pad expand in the enclosed space above the wafers W, so that the expanded pad hold the wafers with moderate pressure. In this way, the semiconductor wafers are properly placed in the device with no excessive stress.

Consequently, the semiconductor wafers packed in accordance with the method of the present invention are always pressed with proper pressure. Therefore, they are safely protected against any'impacts and friction from outside during transportation. The foam pad used in practicing the present invention becomes gradually expanded when air is introduced thereinto and, therefore, there is no fear of injuring the wafers by improper stress. Furthennore, since the entire body of foam material is enclosed within plastic film, it is evenly expandable by piercing the film, and the semiconductor wafers remain free from injury.

Another example of the practice of the invention is shown by FIG. 7. The device of this example is composed of a holder 1', of W-shaped block-type like that shown in FIG. 1, removably disposed in a receptacle 17 having one of its end walls removed, and a covering ele ment 2, having one side wall 18, which, when properly positioned, serves as an end wall for the receptacle 17.

According to this device, the holder 1 accommodated with wafers W is put into the receptacle 17 from above or from the end, while the removal of the wafers W from the holder 1 is conducted after the holder 1 is first taken out of the receptacle 17.

FIG. 8 shows still another example of the practice of the invention. The device shown therein is composed of a receptacle 19, having a section like with one of its end walls removed, enclosing a holder ll of like shape, having a groove wherein a number of cuts 3 are provided in parallel, and a covering element 2", having an end wall 20 which serves as an end wall for receptacle 19. In this device, the wafers W are inserted or removed only from the front part of the receptacle as seen in the figure.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A device for storing and transporting circular semi conductor wafer disks comprising, in combination, a blocktype holder defining at least one generally V-shaped groove extending longitudinally thereof, each groove having opposing upwardly diverging walls and each wall being formed with a plurality of longitudinally spaced parallel transverse grooves with outwardly diverging surfaces, corresponding transverse grooves in the two walls lying in the same transverse plane to receive respective wafers engaging surfaces of the transverse grooves at the wafer edges only, with the wafers in upright position; a covering element cooperable with saidholder to enclose the wafers, and having a top wall and side walls; and a pad of compressed foam material, sealed in a plastic bag and maintained compressed by atmospheric pressure on the plastic bag, positioned in said covering element above wafers in said holder and confined by said side walls of said covering element; said top wall of said covering element being formed with a slit therein to receive a piercing tool to pierce said sealed plastic bag for expansion of said foam material pad into engagement with wafers in said holder and with said top wall.

2. A device, as claimed in claim 1, in which said transverse planes are inclined to the vertical at an angle of substantially 5 whereby the wafers supported in the transverse grooves are similarly inclined to the vertical.

3. A device, as claimed in claim 2, in which said holder has a bottom wall, said transverse grooves being inclined to a perpendicular to said bottom wall by sub- 5. A device, as claimed in claim 1, in which said pad is initially positioned against said top wall of said covering element.

6. A device, as claimed in claim 1, in which said pad is initially positioned in engagement with the upper end of said receptacle when said covering element is positioned on said receptacle to enclose said holder.

9. A device, as claimed in claim 1, including a receptacle having a bottom wall, two side walls and a rear wall interconnecting said side walls; said bottom wall seating two said block-type holders; the side wall of said covering element being engageable with the side walls and said rear wall of said receptacle; said covering element having a front wall closing the open front end of said receptacle.

10. A device, as claimed in claim 1, including a receptacle having a bottom wall, two side walls and a rear wall; said receptacle side walls initially divering upwardly and outwardly and then extending perpendicularly to said receptacle bottom wall; said block-type holder being seated in said receptacle in engagement with the diverging side wall portions thereof; the side walls of said covering element engaging the side walls and rear wall of said receptacle, and said covering element having a front wall closing the open end of said receptacle.

11. A method of storing and transporting circular semi-conductor wafer disks comprising the steps of positioning a plurality of semi-conductor wafer disks in parallel upright relation in a holder; positioning, on the upper edges of the disks, a pad of compressed foam material, sealed in a plastic bag and maintained compressed by atmospheric pressure on the plastic bag; positioning a covering element having a top wall and side walls in engagement with said holder to enclose said disks; and then thrusting a piercing tool through a slit in the top wall of said covering element into said bag to pierce the latter for expansion of the foam material within the space between the upper edges of the wafers and the inner surfaces of said covering element.

12. A method for storing and transporting circular semi-conductor wafer disks comprising the steps of positioning a plurality of semi-conductor wafer disks in parallel upright relation in a holder; providing a covering element having a top wall and side walls; positioning, in engagement with the inner surface of the top wall of the covering element, a pad of compressed foam material, sealed in a plastic bag and maintained compressed by atmospheric pressure on the plastic bag, with the plastic bag being confined by the side walls of the covering element; positioning the covering element with the pad positioned therein on the holder to enclose the disks; and then thrusting a piercing tool through a slit in the top wall of the covering element into said bag to pierce the same for expansion of the foam material within the space between the upper edges of the disks and the inner surface of said covering element top wall.

Claims

1. A device for storing and transporting circular semi-conductor wafer disks comprising, in combination, a block-type holder defining at least one generally V-shaped groove extending longitudinally thereof, each groove having opposing upwardly diverging walls and each wall being formed with a plurality of longitudinally spaced parallel transverse grooves with outwardly diverging surfaces, corresponding transverse grooves in the two walls lying in the same transverse plane to receive respective wafers engaging surfaces of the transverse grooves at the wafer edges only, with the wafers in upright position; a covering element cooperable with said holder to enclose the wafers, and having a top wall and side walls; and a pad of compressed foam material, sealed in a plastic bag and maintained compressed by atmospheric pressure on the plastic bag, positioned in said covering element above wafers in said holder and confined by said side walls of said covering element; said top wall of said covering element being formed with a slit therein to receive a piercing tool to pierce said sealed plastic bag for expansion of said foam material pad into engagement with wafers in said holder and with said top wall.

2. A device, as claimed in claim 1, in which said transverse planes are inclined to the vertical at an angle of substantially 5* whereby the wafers supported in the transverse grooves are similarly inclined to the vertical.

3. A device, as claimed in claim 2, in which said holder has a bottom wall, said transverse grooves being inclined to a perpendicular to said bottom wall by substantially 5*.

4. A device, as claimed in claim 2, in which said holder has a bottom wall; said transverse planes extending substantially perpendicularly to said bottom wall; said holder being supported in a retainer with its bottom wall inclined to the horizontal by substantially 5*.

5. A device, as claimed in claim 1, in which said pad is initially positioned against said top wall of said covering element.

6. A device, as claimed in claim 1, in which said pad is initially positioned in engagement with the upper edges of wafers in said holder.

7. A device, as claimed in claim 1, including a receptacle having a bottom wall and upwardly extending side walls, said holder resting on said bottom wall and said covering element cooperating with said receptacle to enclose said holder and any wafers supported therein.

8. A device, as claimed in claim 7, in which said receptacle has a rear wall and a pair of side walls; said covering element having a front wall closing the front end of said receptacle when said covering element is positioned on said receptacle to enclose said holder.