Wafer container with cushion sheets

• US 7,588,150 B2
• Filed: 07/24/2007
• Issued: 09/15/2009
• Est. Priority Date: 07/25/2006
• Status: Expired due to Fees

• Current Assignee: Miraial Company Limited
• Original Assignee: Miraial Company Limited
• Inventors: Kasama, Nobuyuki
• Primary Examiner(s): Bui; Luan K
• Application Number:
  US12/281,491
• Publication Number:
  US 20090050518A1
• Time in Patent Office: 784 Days
• Field of Search: 206/303, 206/454, 206710-712, 206/722, 206/723, 206/724, 206/521, 206/591, 206/594, 206/509, 206/511, 206/524.8, 206/832, 211/41.18
• US Class Current: 206/710
• CPC Class Codes: H01L 21/67346 characterized by being specially adapted for supporting a single substrate or by comprising a stack of such individual supports
• CPC Class Codes: H01L 21/67369 characterised by shock absorbing elements, e.g. retainers or cushions

Abstract

A wafer-retaining cushion sheet (5) has a wafer suction-adhering surface (5C) formed on a surface thereof, which adheres by suction to a semiconductor wafer (W). A wafer tray (1) is provided with a plurality of bottom openings (17) opening to the reverse side of the wafer-retaining cushion sheet (5), an air chamber (16) communicating with the bottom openings, and an air inlet (11) for supplying pressurized air into the air chamber (16) from the outside. Consequently, when pressurized air is supplied into the air chamber (16) through the air inlet (11) to increase the air pressure in the air chamber (16), the wafer-retaining cushion sheet (5) is elastically deformed into an inflated form at regions facing the bottom openings (17), thus causing separation between the semiconductor wafer (W) and at least a part of the wafer suction-adhering surface (5C) of the wafer-retaining cushion sheet (5).

Claims

1. A cushioned wafer container comprising:

a plurality of mutually superimposed wafer trays each for retaining a semiconductor wafer; and

an elastic wafer-retaining cushion sheet attached to a top of each of said wafer trays to place said semiconductor wafer thereon;

wherein said semiconductor wafer placed on a surface of said wafer-retaining cushion sheet is accommodated in an interior space formed between each of said wafer trays and another of said wafer trays that is adjacently superimposed thereover;

said wafer container further comprising;

a wafer suction-adhering surface formed on the surface of said wafer-retaining cushion sheet, said wafer suction-adhering surface adhering by suction to said semiconductor wafer;

said wafer trays each being provided with a plurality of bottom openings opening to a reverse side of said wafer-retaining cushion sheet, an air chamber communicating with said bottom openings, and an air inlet for supplying pressurized air into said air chamber from an outside;

wherein when pressurized air is supplied into said air chamber through said air inlet to increase air pressure in said air chamber, said wafer-retaining cushion sheet is elastically deformed into an upwardly inflated form at regions facing said bottom openings, thus causing separation between said semiconductor wafer and at least a part of the wafer suction-adhering surface of said wafer-retaining cushion sheet.

2. The cushioned wafer container of claim 1, wherein the wafer suction-adhering surface of said wafer-retaining cushion sheet is formed by a multiplicity of minute suction cups, so that pressing said minute suction cups against said semiconductor wafer causes said semiconductor wafer to be secured by suction to said minute suction cups.

3. The cushioned wafer container of claim 1, wherein said wafer-retaining cushion sheet has a size sufficiently large to retain substantially a whole surface of said semiconductor wafer, said wafer suction-adhering surface being formed on at least a part of an obverse side of said wafer-retaining cushion sheet.

4. The cushioned wafer container of claim 3, wherein said wafer suction-adhering surface is formed only at positions of said wafer-retaining cushion sheet that are coincident with said bottom openings formed in each of said wafer trays.

5. The cushioned wafer container of claim 3, wherein said wafer suction-adhering surface is formed only at positions of said wafer-retaining cushion sheet that are not coincident with said bottom openings formed in each of said wafer trays.

6. The cushioned wafer container of claim 3, wherein said wafer suction-adhering surface is distributed on said wafer-retaining cushion sheet at a uniform density or at locally different densities.

7. The cushioned wafer container of claim 6, wherein a remaining part of the obverse side of said wafer-retaining cushion sheet other than said wafer suction-adhering surface is recessed from said wafer suction-adhering surface.

8. The cushioned wafer container of claim 1, wherein a tray suction-adhering surface that airtightly adheres by suction to the top of said wafer tray is formed on the reverse side of said wafer-retaining cushion sheet.

9. The cushioned wafer container of claim 8, wherein, regarding respective adhesive forces of the wafer suction-adhering surface and tray suction-adhering surface of said wafer-retaining cushion sheet, the adhesive force of said wafer suction-adhering surface relative to said semiconductor wafer is set smaller than the adhesive force of said tray suction-adhering surface relative to the top of said wafer tray.

10. The cushioned wafer container of claim 8, wherein said wafer-retaining cushion sheet comprises an integrated stack of a tray suction-adhering layer having said tray suction-adhering surface, a cushion layer functioning as an elastic cushion, and a wafer suction-adhering layer having said wafer suction-adhering surface.

11. The cushioned wafer container of claim 10, wherein said cushion layer is formed of one of an elastic elastomeric polymer material and an elastic foamed polymer material.

12. The cushioned wafer container of claim 1, wherein said bottom openings are evenly distributed throughout a region facing the reverse side of said wafer-retaining cushion sheet.

13. The cushioned wafer container of claim 1, wherein said bottom openings formed in said wafer tray each have a groove shape extending radially outward from a center thereof.

14. The cushioned wafer container of claim 1, further comprising:

an elastic wafer-pressing cushion sheet disposed on a bottom of each of said wafer trays to press said semiconductor wafer against said wafer-retaining cushion sheet.

15. The cushioned wafer container of claim 14, wherein at least one of said wafer-retaining cushion sheet and said wafer-pressing cushion sheet has a surface electrical resistance in a range of from 10⁸Ω

to 10¹⁰Ω

.

16. The cushioned wafer container of claim 1, further comprising:

a tray connecting mechanism for releasably connecting together said mutually superimposed wafer trays into a stack such that the stack of said superimposed wafer trays can be disconnected at any desired position in the stack.

17. A cushioned wafer container comprising:

a plurality of mutually superimposed wafer trays each for retaining a semiconductor wafer; and

an elastic wafer-retaining cushion sheet attached to a top of each of said wafer trays to place said semiconductor wafer thereon;

wherein said semiconductor wafer placed on a surface of said wafer-retaining cushion sheet is accommodated in an interior space formed between each of said wafer trays and another of said wafer trays that is adjacently superimposed thereover;

said wafer container further comprising;

a wafer suction-adhering surface formed on the surface of said wafer-retaining cushion sheet, said wafer suction-adhering surface adhering by suction to said semiconductor wafer;

said wafer trays each being provided with a plurality of bottom openings opening to a reverse side of said wafer-retaining cushion sheet, an air chamber communicating with said bottom openings, and a suction port for externally sucking out air from said air chamber;

wherein when the air in said air chamber is externally sucked out through said suction port to reduce air pressure in said air chamber, said wafer-retaining cushion sheet is elastically deformed in a state of being sucked toward said bottom openings at regions thereof facing said bottom openings, thus causing separation between said semiconductor wafer and at least a part of the wafer suction-adhering surface of said wafer-retaining cushion sheet.

18. The cushioned wafer container of claim 17, wherein said wafer suction-adhering surface is formed only at positions of said wafer-retaining cushion sheet that are coincident with said bottom openings formed in each of said wafer trays.