JPH10284584A - Method for packing wafer product case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain silicon wafers at the same cleanliness as that when the wafers are manufactured without causing pinholes in the welded sections of resin-made packing bags at the time of transporting wafer product cases by specifying the atmospheric pressures in the packing bags. SOLUTION: The atmospheric pressures in packing bags are adjusted within a range of 0.90-0.99 atm, preferably, 0.95-0.99 atm. Various kinds of resins can be used for the packing bags, but an aluminum-coated polyester which is coated with aluminum so as to prevent moisture from getting in polyester that discharges a little amount of material, can resist friction, and can be welded is preferable. After one bag containing product cases is set on a sealer machine and the inside of the bag is deaerated with a pump, the mouth of the bag is welded. Therefore, silicon wafers can be transported in clean states even when the bag is transported by air, because no pinhole occurs in the welded section and the fluctuation of humidity with time can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging method when a silicon wafer used as a semiconductor material is stored in a required product case and transported, and the pressure inside the packaging bag is slightly reduced, that is, the pressure is reduced. The present invention relates to a method of packaging a wafer product case in which a pinhole generated in a welded portion of a bag is prevented in an air-treated state, thereby preventing air pollution and the like of a silicon wafer.

[0002]

2. Description of the Related Art Silicon wafers used as semiconductor materials are required to have higher precision and higher cleanliness in accordance with today's demand for higher density of semiconductor devices. It is handled so that it will not be contaminated during transportation and storage until it is put into the semiconductor device process at home.

[0003] That is, since silicon wafers are manufactured in a class 1 clean room, it is necessary to maintain this degree of cleanness when transporting and storing them. A packing method is adopted in which a lid having a packing is housed, the lid is closed, and this is put in a resin bag and sealed by welding.

[0004]

After the wafer product case is hermetically sealed and packed in a resin bag, it is transported by land transportation, sea transportation, air transportation, or the like. Although it is sealed through a plastic bag, it can replace the atmosphere inside the resin bag. In particular, pinholes often occur at the welded part of the packaging bag after air transportation. ) And the product case are in direct contact with each other, causing atmospheric contamination of the silicon wafer, which has been a major problem in transportation.

[0005] The inventor pursued the cause of the occurrence of pinholes in the resin bag of the wafer product case. As a result, in the case of air transportation, the air pressure was 1 atm, which is the atmospheric pressure on land, but was reduced to 0.8 atm during flight. At this time, the state of the packaging bag does not change in the atmosphere, but the pressure changes during air transportation, that is, 1 atm in the bag and 0.8 atm in the air, so that the packaging bag expands. However, it was found that a pinhole was generated from the welded portion at both ends of the bag, which is the weakest portion of the bag, and the bag was torn due to this, without being able to withstand the expansion and contraction of the bag.

According to the present invention, there is provided a wafer product case capable of maintaining a clean degree during the production of a silicon wafer without producing pinholes in a welded portion of a resin packaging bag used for packaging the case when transporting the wafer product case. It aims to provide a packaging method for product cases.

[0007]

The inventor has studied a packaging method of a wafer product case which can maintain a clean degree at the time of manufacturing a silicon wafer, and it has been known that vacuum packaging is conventionally performed (Japanese Patent Laid-Open No. 4-128139). No., JP-A-6-92386), which is used in various packaging forms, and can reduce pinholes generated during air transportation by performing decompression treatment. In addition, after various investigations, the product case was deformed by degassing the inside of the packaging bag and expanding the packaging bag to some extent during air transportation, instead of reducing the pressure in the same way as the outside air pressure during air transportation. The present inventors have found that pinholes generated in the welded portion of the packaging bag can be reliably prevented without being caught or opened.

That is, according to the present invention, in a packaging method in which a product case in which a silicon wafer is stored and a lid is closed is sealed in a resin bag for transportation and storage, the pressure in the packaging bag is 0.90 atm. ０．９0.99 atm.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, in order to prevent pinholes from being generated at the welded portion of the packaging bag, it is necessary to deaerate the pressure in the packaging bag to at least 0.99 atm. Although the pinhole resistance is improved when the pressure is reduced below, the product case is airtight because the packing material is used, and the case cannot be opened due to such reduced pressure, or the case is deformed when the case thickness is thin. Therefore, the air pressure in the packaging bag is 0.90 atm to 0.
The range is 99 atm. More preferably, 0.95a
tm to 0.99 atm. The barometric pressure is a value measured by the ground standard standard.

In the present invention, as a method for degassing the packaging bag, a commercially available degassing sealer can be used. The product case is packed in a packaging bag and set in the sealer.
After completing the deaeration of the inside of the packaging bag by the pump, the pressure inside the packaging bag is adjusted to 0.90 atm to 0.9 by welding the mouth of the packaging bag.
9 atm.

In the present invention, various resin bags can be used for the packaging bag, and there is no particular limitation. However, it is possible to prevent moisture from penetrating into the polyester, which emits little substance from the resin, is resistant to friction, and can be welded. Polyester bags coated with aluminum are preferred.

[0012]

【Example】

Example 1 A normal packaging method in which a product case is put in and then a bag mouth is welded using a polyester bag in which aluminum is coated on a packaging bag, and a bag mouth is welded after degassing to 0.95 atm. After carrying out a packaging method according to and holding the pressure from the atmospheric pressure to 0.8 atm in the decompression chamber for 3 hours, a test to return to the atmospheric pressure was again performed, and the tearing of the packaging was confirmed visually and by using a permeate. In the case of the normal method, about half the pinholes were formed in the welded portions, but in the case of the package according to the present invention, there was no such hole.

Example 2 After the packaging method of Example 1 was carried out, transportation by air from Japan to the United States was performed, and the change in humidity in the packaging bag was measured over time. When confirmed by ion chromatography, the normal packaging showed fine and large fluctuations corresponding to changes in the humidity of the outside air, and in the packaging where a pinhole appeared at the welded part,
Although the increase of each of NO ₂ ⁻ , SO ₄ ²⁻ , and NO ₃ ⁻ ions was remarkable at one digit or more, the packaging of the present invention showed a relatively slow and small change, and the ion level did not change at all. Was not seen.

[0014]

According to the packaging method of the present invention, since the inside of the packaging bag is welded and sealed in a degassed state, even during transportation using an aircraft, pinholes are not generated in the welded portion, and the humidity changes with time. And the silicon wafer can be transported in a clean state at the time of manufacturing.

Claims (2)

[Claims] 1. A packaging method in which a product case in which a silicon wafer is stored and a lid is closed is sealed in a resin bag for transportation and storage, wherein the pressure in the packaging bag is 0.9.
A method of packaging a wafer product case, wherein the method is 0 atm to 0.99 atm. 2. The method of packaging a wafer product case according to claim 1, wherein the resin bag is a polyester bag coated with aluminum.