JPH0648507A - Gas purging method of sealed container - Google Patents

Abstract

PURPOSE:To restrain H2O and O2 which prevents oxidized film from leaking from a container or a storage device by making the inside of the container vacuum temporarily to be replaced with inactive gas. CONSTITUTION:A container 70 where a wafer cassette 30 is stored is moved onto a container deck 64 in a sealed box 60, a vacuum source 80 is driven, and a drive part 67 is driven to open the upper cover 73 of the container 70. When the sealed box 60 reaches prescribed vacuum pressure and a prescribed period passes, a valve 81 is closed, and a valve 83 is opened to feed N2 gas into the sealed box 60. If the inside of the sealed box 60 and the container 70 is replaced with N2 gas and is kept at prescribed positive pressure, the drive part 67 is driven to close the upper cover 73 of the container 70, and the valve 83 is closed to take the container 70 out of the sealed box 60.

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 used in a clean room.

[0002]

2. Description of the Related Art For example, a semiconductor is manufactured in a clean room in which the internal atmosphere is cleaned, and the inter-process transfer in the clean room is performed in order to prevent the adhesion of dust to the semiconductor wafer or the liquid crystal substrate. The cassette containing is stored in a portable sealed 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 a gas such as nitrogen N ₂ gas which is inert to the wafer.

FIG. 4 shows an example of the closed container having the N ₂ gas purging function. In the figure, 10 is a main body of a portable closed container (POD) 1, 11 is a flange provided in an opening 12 of the main body 10, 13 and 13A are sealing materials, 14 is a handle, and 20 is a bottom lid of the closed container. , 30 are wafer cassettes containing the semiconductor wafers W. 40
Is a hermetically-sealed case of a semiconductor surface treatment apparatus, and accommodates a reaction furnace (not shown) for surface treatment, a transfer mechanism including an elevating device, and the like. 42 is an opening for loading / unloading the wafer cassette, and is provided in a part of the upper wall 41 of the case 40. The upper wall 41 is provided with a gas supply pipe 44A having one end opened to the peripheral surface of the opening 42 and the other end connected to an inert gas cylinder (N ₂ gas cylinder in this example) 50, and one end is opened 42. An exhaust gas pipe 44B having an opening on the peripheral surface of the exhaust gas and an opening on the other end outside the box is provided. 45
A is an air supply valve and 45B is an exhaust valve. Reference numeral 46 denotes an elevating table of the elevating 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. 40A is a lock mechanism. It should be noted that the inside of the hermetically sealed case 40 is in a nitrogen N ₂ gas atmosphere and is usually pre-pressurized to atmospheric pressure or higher.

The lid 20 of the closed container is a hollow body and has a locking mechanism as shown in FIG. 5, for example. 24
Is a cam, and 25 is a plate-shaped lock arm, which has a rolling element 25a and is supported by a cantilever so as to be capable of advancing and retracting in the longitudinal direction and tilting. 26 is a fulcrum member, and 27 is a spring.
The cam shaft 28 extends from the center of the upper wall of the lifting table 46 into the lid 20, and spline-engages with the cam 44 when the lid 20 is concentrically placed on the lifting table 46. The lift table 46 incorporates a cam shaft drive mechanism 29 for rotating the cam shaft 28 by a predetermined angle, and the cam shaft drive mechanism 29 and the cam shaft 28 constitute an unlocking / locking mechanism. A recess 12A with which the lock arm 25 is engaged is formed on the inner peripheral surface of the opening 12 of the main body 10.

In this configuration, a transfer device (not shown, such as a mobile robot equipped with a handling device) transfers the closed container 1 containing the wafer cassette 30 onto the closed case 40 of the surface processing apparatus as shown in FIG. And place
The flange 11 of the closed container 1 is pressed and fixed by the lock mechanism 40A.

Next, the unlocking / locking mechanism is actuated to release the engagement between the lock arm 25 and the recess 12A, lower the elevating table 46, and open the bottom lid 20. After opening the bottom lid 20 and opening the air supply valve 45A and the exhaust valve 45B,
N ₂ gas from 50 (N ₂ gas cylinder in this example) inert gas cylinder flows into the body 10 of the container 1, the air that was in the body 10 of the container 1 is discharged through the exhaust gas pipe 44B.

[0008]

As described above, in recent years, the wafer cassette is transferred and stored in a closed container filled with nitrogen N ₂ gas. However, the inside of the closed container is filled with nitrogen N ₂ gas. H ₂ O or O ₂ (hereinafter referred to as adsorption / occlusion) adhered to the inner surface of the closed container, the wafer cassette, the wafers stored in the wafer cassette or the surface of the cassette is simply replaced by an inert gas such as (Gas or liquid) cannot be removed, so that an oxide film is formed by natural oxidation with the lapse of time, and the yield is reduced.

The present invention has been made to solve this problem, and H, which causes the formation of an oxide film after gas purging, is formed.
_An object of the present invention is to provide a gas purging method for a hermetically sealed container, which can prevent ₂ O and O ₂ from coming out of a container or a stored item.

[0010]

In order to achieve the above-mentioned object, the present invention provides a sealed container for storing and transporting a substrate for an electronic device according to the first aspect of the invention. In the case of gas purging with an inert gas, the gas was purged with the above-mentioned inert gas and then purged.

According to a second aspect of the present invention, a closed container is housed in a closed box which is connected to a vacuum source and an inert gas source through a pipe, and the closed container is communicated with the closed box to evacuate and inactivate. The gas was purged with various gases.

According to a third aspect of the present invention, the closed container is hermetically placed on the closed box connected to the vacuum source and the inert gas source through the pipe, and the bottom lid of the closed container is opened into the closed box. The inside of the closed container is communicated with the inside of the closed box to perform vacuuming and gas purging with an inert gas.

[0013]

In the present invention, the inside of the container is temporarily evacuated, and is adsorbed and occluded on the inner surface of the container or the surface of the container contents. Pull it out and discharge it out of the container,
Then from filling the inert gas is significantly reduced as compared in H ₂ O and O ₂ Mother conventional remaining on coming out into the container H ₂ O or O ₂ in the amount or surface after purging.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 60 is a closed box (vacuum container) for purging, which is an upper opening 6 of the box 60.
There is an upper lid 63 that hermetically closes 1 with a sealing material 62 interposed, and a container stand 64 is installed inside.
Reference numeral 70 denotes an upper lid type portable airtight container, which has an upper lid (attached by a hinge (not shown)) 73 that hermetically closes the cassette loading / unloading opening 72 via a sealing material 71. Reference numeral 65 denotes a lid opening / closing device, which includes a handling arm 66 for opening and closing the lid and a drive unit 67 of the arm, and is installed at an appropriate position of the closed box 60.

A pipe 68 for vacuum evacuation and a pipe 69 for supplying an inert gas or a dry gas are tightly penetrated through the side wall of the purging closed box 60. Reference numeral 80 is a vacuum source, 81 is a valve, 82 is an inert gas (for example, N ₂ gas) storage tank, and 83 is a valve.

In this embodiment, the wafer cassette 30 is used.
The container 70 accommodating the above is transferred onto the container base 64 in the closed box 60 by a transfer device (not shown), and then the vacuum source 80 is driven and the drive unit 67 is driven to open the upper lid 73 of the container 70.

When the inside of the closed box 60 becomes a predetermined vacuum degree and a predetermined time elapses, the valve 81 is closed and the valve 8 is closed.
3 is opened, and N ₂ gas is supplied into the closed box 60. When the inside of the closed box 60 and the inside of the container 70 are replaced with N ₂ gas and the inside of the closed box 60 reaches a predetermined positive pressure (a slight positive pressure), the driving unit 67 is driven to drive the container 7
0 of the container 70 by closing the upper lid 73 and the valve 83.
Is taken out from the closed box 60.

In this embodiment, since the inside of the container 70 is once made to have a negative pressure, the moisture and oxygen adhering to the inner surface portions of the container 70 and the bottom lid 73, the surface portion of the wafer W and the wafer cassette 30. Moisture and oxygen adhering to the inside of the container 70 come out so as to ooze out from the inner surface and the surface, and are separated from the inner surface and the surface, exhausted to the outside, and then the container 70.
Will be replaced with N ₂ gas.

FIG. 3A shows a change in H ₂ O concentration in the closed container after the gas purging according to the present embodiment,
(B) shows the change in H ₂ O concentration in the closed container after the conventional gas purging. Further, (c) of the figure shows O in the closed container after the gas purging according to the present embodiment.
₂ shows the change of the O ₂ concentration, and FIG. 5D shows the change of the O ₂ concentration after the O ₂ concentration was lowered to 0 ppm by the conventional method. The volume of the closed container used in this experiment was 540 liters, and four wafer cassettes each containing 25 wafers were stored in the closed container for the experiment.

As is clear from the results of this experiment, when the vacuum is evacuated and then the inert gas is purged, H ₂ O coming out from the inner surface of the container, the wafer, and the wafer cassette is discharged.
Since the amount of or O ₂ is remarkably reduced as compared with the conventional case, it is possible to suppress the growth of the natural oxide film even when it is stored in the container for a long period of time.

In the above embodiment, the closed box 6 for purging is used.
The container 70 is placed in the container 0 to perform vacuuming and gas purging. However, when the container is the bottom lid type container 1 shown in FIG.
As shown in FIG. 5, the lifting table 46 of the lifting device is built in, and the box upper wall 60U is used as a pedestal on which the container 1 is placed.
An opening 42 through which 6 goes in and out is provided. And box 6
One end of a pipe 68 for vacuum exhaust and one end of a pipe 69 for supplying an inert gas or a dry gas are opened in 0.

In the above embodiment, the case where the gas is purged with the inert gas has been described, but the wafer may be purged with the dry air which can be said to be the inert gas.

[0024]

As described above, according to the present invention, the inside of the container is temporarily evacuated, and is adsorbed and occluded on the inner surface of the container or the surface of the container contents. The gas or liquid that cannot be discharged is withdrawn and discharged to the outside of the container, and then the inert gas is filled. Therefore, the amount of H ₂ O and O ₂ coming into the container after purging is significantly reduced compared to the conventional one. Therefore, the growth of the natural oxide film is suppressed.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic vertical sectional view showing another embodiment of the present invention.

[Figure 3] shows in comparison with the time course of H ₂ O and O ₂ concentration in the container after purging with the above embodiment, the time course of H ₂ O and O ₂ concentration in the container after conventional gas purge FIG.

FIG. 4 is a view showing a conventional portable sealed container.

FIG. 5 is a view showing an unlocking / locking mechanism of the portable closed container.

[Explanation of Codes] 1 Portable closed container 10 Main body of closed container 20 Bottom lid of closed container 30 Wafer cassette 60 Closed box 60U Top wall of closed box 63 Top lid of closed box 64 Lifting table 68 Evacuation pipe 69 Gas supply gas Piping 70 Portable sealed container 80 Vacuum source 82 Inert gas source

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiya Morita 100 Takegahana-cho, Ise-shi, Mie Shinko Electric Co., Ltd.Ise Works (72) Inventor Kono, 100 Takegahana-cho, Ise-shi, Mie Shinko Electric Co., Ltd. Ise In-house (72) Inventor Mitsuhiro Hayashi 100, Takegahana-cho, Ise-shi, Mie Shinko Electric Co., Ltd.In Ise Works (72) Inventor Atsushi Okuno 100, Takegahana-cho, Ise-shi, Mie Shinko Electric Co., Ltd. (72) Invention Akio Nakamura 100, Takegahana-cho, Ise City, Mie Prefecture Shinko Electric Co., Ltd.

Claims (3)

[Claims] 1. When the inside of a closed container for housing and transporting a substrate for electronic equipment is gas-purged with a gas inert to the contents stored in the closed container, the inert gas is drawn after vacuuming. Gas purging method for closed containers characterized by gas purging with 2. A closed container is housed in a closed box connected to a vacuum source and an inert gas source through a pipe, the closed container is communicated with the closed box, and evacuation and gas purging with an inert gas are performed. The method for purging a gas in a closed container according to claim 1, wherein 3. A hermetically sealed container is placed on a hermetically sealed box connected to a vacuum source and an inert gas source through a pipe, and the bottom lid of the hermetically sealed container is opened into the hermetically sealed box so that the hermetically sealed container is closed. 2. The gas purging method for a closed container according to claim 1, wherein the closed container is communicated with the closed box to perform vacuuming and gas purging with an inert gas.