JP3252457B2 - Gas purging method for portable closed containers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas purging method for a portable closed container or the like used in a clean room.

[0002]

2. Description of the Related Art For example, semiconductors are manufactured in a clean room in which the internal atmosphere is cleaned, but the inter-process transfer in the clean room involves storing the semiconductor wafers in order to prevent dust from adhering to the semiconductor wafers. The wafer cassette is stored in a portable closed container.

Further, in recent years, in order to prevent the growth of an oxide film due to natural oxidation of a semiconductor wafer, the atmosphere inside the closed container is replaced with an inert gas such as nitrogen N ₂ gas.

FIG. 2 shows an example of a closed container provided with this N ₂ gas purging function. 1, reference numeral 10 denotes a main body of a portable closed container (POD) 1; 11, a flange provided in an opening 12 of the main body 10;
Reference numeral 4 denotes a handle, reference numeral 20 denotes a lid of a closed container, and reference numeral 30 denotes a wafer cassette containing semiconductor wafers W. Reference numeral 40 denotes a sealed case of a semiconductor surface treatment apparatus, which accommodates a not-shown surface treatment reaction furnace, a transport mechanism including an elevating device, and the like. Reference numeral 42 denotes an opening for taking in and out the wafer cassette, which is provided in a part of the upper wall 41 of the case 40. One end of the upper wall 41 is open on the peripheral surface of the opening 42, and the other end is an inert gas cylinder (N ₂ gas cylinder in this example) 50.
Is provided, and an exhaust gas pipe 44B is provided, one end of which is open on the peripheral surface of the opening 42 and the other end of which is open outside the box. 45a is an air supply valve, and 45B is an exhaust valve. Reference numeral 46 denotes a lifting platform of the lifting device, which has a size that can be fitted into the opening 42 with a gap G left between the opening 42 and the peripheral surface of the opening 42. Note that the inside of the closed case 40 is a nitrogen N ₂ gas atmosphere, and is pre-pressed to an atmospheric pressure or higher.

The lid 20 of the closed container is a hollow body and has a lock mechanism as shown in FIG. 3, for example. 24
Is a cam, 25 is a plate-shaped lock arm, which has a rolling element 25a and is cantilevered so as to be able to advance and retreat in the longitudinal direction and to be tiltable. 26 is a fulcrum member, and 27 is a spring.
The camshaft 28 extends into the lid 20 from the center of the upper wall of the elevator 46, and is spline-engaged with the cam 44 when the lid 20 is concentrically mounted on the elevator 46. The elevating table 46 has a built-in camshaft drive mechanism 29 for rotating the camshaft 28 by a predetermined angle, and the camshaft drive mechanism 29 and the camshaft 28 constitute an unlocking / locking mechanism. Note that a recess 12 </ b> A with which the lock arm 25 is engaged is formed on the inner peripheral surface of the opening 12 of the main body 10.

[0006]

BRIEF Problem to be Solved] Thus, in recent years, although as to transport and store in the wafer cassette in a sealed container filled with nitrogen N ₂ gas, nitrogen N ₂ gas inside the sealed container H ₂ O or O ₂ (hereinafter, adsorbed / occluded gas or liquid) adhering to the inner surface of the closed container, the surface of the wafer cassette, or the surface of the cassette stored in the wafer cassette, to the extent of replacement with an inert gas such as Cannot be removed, an oxide film is formed by natural oxidation, and the yield decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and provides a gas purging method for a closed container which can reliably remove adsorbed / occluded gas and liquid in the container and perform gas purging by simple means. The purpose is to:

[0008]

According to the present invention, in order to achieve the above object, the present invention is applied to a clean room.
Detachable to the opening of the portable closed container made of plastic
By raising and lowering the bottom cover provided in the
When the eha is stored in a closed container through the opening,
The inert gas supplied through the opening in the closed container
When purging with an inert gas and pre-pressurizing to above atmospheric pressure,
By performing the process at a high temperature of the inert gas, the
After desorption of stored and stored gases and liquids by heat,
The configuration is such that switching to active gas is performed .

[0009]

[0010]

[0011]

[0012]

According to the present invention, the adsorbed / occluded gas or liquid on the inner wall of the container or the surface of the container is desorbed / removed by heat.

[0013]

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

In FIG. 1, reference numeral 51 denotes a heater surrounding the gas supply pipe 44A, 52 denotes a heater power supply (for example, a controllable rectifier), 53 denotes an AC power supply, and 54 denotes a temperature controller. The temperature controller 54 compares the temperature θf in the supply gas pipe 44A with the set temperature θr, and controls the output of the heater power supply 54 so that the deviation between the two becomes zero. The other structure is the same as the conventional one.

In this configuration, the atmosphere in the POD 10 is first replaced with an N ₂ gas (hot gas) having a temperature θr. Since this temperature θr is set to a temperature at which H ₂ O or O ₂ is vaporized (evaporated), POD1
The residual gas molecules (H ₂₎ adhered to the inner wall of the main body 10, the inner surface of the lid 20, the surface of the wafer cassette, and the surface of the wafer W.
O and O ₂ ) are vaporized and discharged to the outside through the exhaust pipe 44B.

In the present embodiment, after the hot gas is supplied into the POD 1 for a certain period of time, the output of the heater power supply 12 is stopped, and thereafter, the gas purge with the normal temperature N ₂ gas is performed.

In this embodiment, the residual gas molecules (such as H ₂ O and O ₂ ) are vaporized by the hot gas.
Needless to say, D1 may be heated from the outside to raise the temperature of the internal atmosphere. In this case, if the POD 1 is made of plastic, it has a heat insulating effect, so that a strong heat source is required.

In this embodiment, since the attached gas molecules are vaporized and removed by heat, it is inexpensive as compared with the case where a vacuum source is not required as in the case of vaporizing the attached gas molecules by applying a negative pressure. The attached residual gas molecules can be vaporized and removed at a low cost.

In the case where the present embodiment is applied to a closed container for storing a wafer or a container used in a clean room, the wafer adheres to the inner surface of the container, the wafer cassette, or the surface of the cassette stored in the wafer cassette. H ₂ O and O
_{Since 2} can be removed, formation of an oxide film due to natural oxidation is reduced, and the yield is improved.

[0020]

As described above, the present invention vaporizes and removes the residual gas molecules adhered by heat.
It is possible to surely remove the adhering residual gas molecules and greatly improve the gas purging effect as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a view showing a conventional portable closed container.

FIG. 3 is a view showing a locking mechanism of the portable closed container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Closed container 10 Closed container main body 20 Closed container lid 30 Wafer cassette 40 Sealed case of semiconductor surface treatment apparatus 42 Opening 46 Lifting table 50 Gas cylinder 51 Heater 52 Heater power supply 53 AC power supply 54 Temperature controller

Continuing from the front page (72) Inventor Moriya Hiya 100 Takegahana-cho, Ise-shi, Mie Prefecture Inside Kobe Electric Machinery Co., Ltd.Ise Seisakusho (72) Inventor, etc. (72) Inventor Mitsuhiro Hayashi 100 Takegahana-cho, Ise-shi, Mie Prefecture Shinko Electric Machinery Co., Ltd.Ise Mfg. Co., Ltd. Inventor Akio Nakamura 100 Takegahana-cho, Ise-shi, Mie Prefecture Inside Ise Seisakusho, Kobe Electric Co., Ltd. (56) 4-159918 (JP, A) JP-A-5-74921 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/68 B65B 31/04 B65G 49/00

Claims (1)

(57) [Claims] A plastic used in a clean room.
It is provided detachably at the opening of a portable closed container made of
The semiconductor wafer is moved up and down by raising and lowering the bottom lid.
When housed in an airtight container through the opening, and when the inside of the airtight container is gas-purged with the inert gas supplied through the opening and pre- pressurized to an atmospheric pressure or higher, the temperature of the inert gas is increased. portable sealed container gas purge method characterized by switching to a normal temperature of the inert gas after the adsorption and occlusion gas or liquid in the closed container desorbed by heat by line Ukoto.