JPH07117809A - Vacuum warehouse - Google Patents

Abstract

PURPOSE:To provide a vacuum warehouse having extremely high cleanliness, capable of transferring articles to be stored while keeping the vacuum state. CONSTITUTION:In a vacuum warehouse 1 for storing articles to be stored 12 by vacuum atmosphere, the vacuum warehouse 1 is composed of a vacuum storing chamber 5, a robot chamber 3 and a load lock chamber 2, and respective chambers are hermetically connected to each other through gate valves 6, 7, and a means for keeping vacuum in the vacuum storing chamber 1 even the article to be stored 12 is transferred.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage container used in a semiconductor manufacturing line or the like for storing semiconductor wafers and the like in a highly clean state.

[0002]

2. Description of the Related Art FIG. 9 shows a conventional storage cabinet. For example, 25 silicon wafers for semiconductor manufacturing are put into a carrier made of Teflon or the like and stored in a storage as shown in FIG. This storage has a HEPA filter on the upper part and a shelf below it, and the clean air in the clean room is further cleaned by the HEPA filter to allow air to flow downward, and dust (particles) on the wafers placed on the shelf. ) Is not attached.

However, with the recent miniaturization of semiconductors, a natural oxide film formed on a wafer by oxygen / water in the air is becoming a problem. Therefore, in the storage, a method of flowing a clean dry inert gas such as nitrogen instead of the clean air is also used. However, even in this method, since oxygen / water as impurities contained in dry nitrogen cannot be completely removed and nitrogen is continuously flowed, the particles contained in a trace amount in the nitrogen are contained in the wafer. However, there is a problem that the storage cost increases with the increase of the storage time, and the nitrogen used must be of high purity, so that its running cost is high.

Therefore, recently, a method of storing a wafer in a vacuum has been proposed. In a vacuum, Brownian motion is reduced due to the decrease in the number of gas molecules, so even at atmospheric pressure, small particles such as cigarette smoke floating in the air fall naturally in a short time. Therefore, once a vacuum is created, it is considered that there are few particles floating in the space except very small particles. In a vacuum, the higher the degree of vacuum, the smaller the number of oxygen molecules and water molecules contained in the space.
Therefore, the vacuum atmosphere is an ideal environment for storing wafers.

However, in order to store the wafer in a vacuum, various problems must be solved. First, in the transient state from the atmospheric pressure to the evacuation, particles may adhere to the wafer due to the flow of the airflow during evacuation. Therefore, it is necessary to maintain the vacuum state of the storage chamber in order to prevent contamination of other wafers already stored even when additional wafers and the like are put into the storage chamber.

The second is the selection of a moving mechanism that can be used in a vacuum. In a storage room where high cleanliness must be maintained, dust generation / degassing inside should be minimized. The normal moving mechanism has problems such as lubrication in moving the wafer inside the vacuum chamber. In addition, if a moving mechanism is placed in the same space as the vacuum storage space, the stored wafers will be contaminated due to the effect of dust generation / degassing from the mechanism. Further, if the moving mechanism is contained in the vacuum, human beings cannot repair the device or maintain it unless the pressure is returned to atmospheric pressure during maintenance or when the device fails.

By the way, recently, magnetic bearings and magnetic levitation transfer devices have been attracting attention as moving mechanisms that can be used in vacuum. An example of the structure of this device is disclosed by the applicant in the international patent application PCT / JP93 / 009930. This allows you to move the transported object without contact,
The electromagnet, linear motor, sensor, etc. are placed on the atmosphere side, separated from the vacuum chamber. Therefore, there is no mechanical contact with the moving parts on the vacuum chamber side, and there is no need to put anything that may generate gas or bring particles into the vacuum chamber side, so high cleanliness is required. It is optimal as a moving mechanism used in a vacuum chamber.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to transfer an object to be stored while maintaining a vacuum state, and a vacuum having an extremely high degree of cleanliness. The purpose is to provide a storage.

[0009]

The storage of the present invention is a vacuum storage for storing an object to be stored in a vacuum atmosphere. The vacuum storage includes a vacuum storage chamber, a robot chamber, and a load lock chamber. Each of the chambers is airtightly connected via a gate valve, and is provided with a means for holding the vacuum of the vacuum storage chamber even when the object to be stored is transferred.

[0010]

[Operation] Vacuum storage is a load lock room, robot room,
It is divided into storage rooms, and each is connected via a gate valve. Therefore, by opening and closing the gate valve of each chamber, the wafer can be transferred while maintaining the vacuum in the vacuum storage chamber. The vacuum storage chamber is provided with a wafer storage rack (transportation carriage) that can be moved linearly, and can be moved as needed to store a large amount of wafers in a vacuum state.

[0011]

The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a device configuration of a first embodiment of the present invention. The vacuum storage 1 comprises a load lock chamber 2, a robot chamber 3 and a vacuum storage chamber 5, and the respective chambers are hermetically connected via gate valves 6 and 7. Further, each chamber (room) is connected to a vacuum exhaust system 9 and a clean air (gas) supply source 10 to the vacuum pump,
The pressure can be adjusted independently.

The vacuum storage chamber 5 has a tunnel shape. Inside, a rectangular parallelepiped wafer storage shelf 11 is floated and held in the vacuum chamber by a magnetic levitation device in a non-contact manner and in a non-contact state by a linear motor. Can be moved / stopped. The storage rack 11 is linearly movable in the tunnel-shaped vacuum storage chamber 5.

FIG. 2 is a three-view drawing of the upper surface (A), the vertical section (B), and the horizontal section (C) of the wafer storage shelf. The wafer storage rack 11 corresponds to a transfer carriage of the magnetic levitation transfer device, and in this embodiment, the wafers 12 are stored in three rows. The storage rack 11 is provided with a flying pole target (magnetic material) 13 on its upper surface and an aluminum alloy conductor 14 on its lower surface. The storage shelf 11 main body is
A metal plate that does not have a problem such as gas adsorption is used.

FIG. 3 shows a cross section of the drive mechanism of the storage rack in the vacuum storage chamber. The basic structure is the same as that of the magnetic levitation transfer device, but the difference is that the transfer carriage becomes longer and a plurality of wafers can be placed on the transfer carriage. A levitation electromagnet 21 is provided on the upper surface of the partition wall of the vacuum storage chamber 20, and the magnetic body 13 fixed to the upper surface of the storage shelf 11 is provided.
A magnetic attraction force is applied to the storage shelf 11 so as to float and hold it.
A linear motor 22 is provided on the lower surface of the partition wall 20 to generate an eddy current in the conductor 14 provided on the lower surface of the storage shelf 11 and drive the storage shelf 11 in the vertical direction with respect to the paper surface.
Displacement sensor 23 provided on the lower surface of the vacuum storage chamber partition wall 20
Detects the floating position of the storage rack 11 and feeds it back to a control circuit (not shown) to control the exciting current of the floating electromagnet 21 to control the storage rack 11 to the target floating position.

In this way, in this embodiment, the storage rack 11 accommodating the wafers 12 is suspended by the magnetic attraction force of the levitation electromagnet 21, and the linear motor 2 is used.
It is moved horizontally by 2. The stop holding device 24
A braking force is applied to the moving storage rack 11 to stop and hold the storage rack 11 at a predetermined position.

The magnetic levitation method is not limited to this embodiment, but the type in which the primary side of a magnet or the like moves with the secondary side,
That is, in the state where the storage rack 11 is suspended by the magnetic attraction force of the levitation electromagnet 21, the levitation electromagnet 21 is separated from the partition wall 20.
It is also possible to use a magnetic levitation transfer device of the type in which the storage rack 11 moves in the vacuum storage chamber as the storage rack 11 moves along a track outside.

Although the magnetic levitation transfer is used to move the storage rack in the above-described embodiment, it is not always necessary to use this, and if the problem of contamination is not so severe, the one shown in FIG. In this way, it is possible that the storage rack is provided with the wheels 25 so that the storage shelves come into contact with the lower surface of the storage chamber partition wall 20 to travel. In this embodiment, the storage rack 11 is horizontally driven by a linear motor 22.

The robot room 3 contains a normal cylindrical coordinate type vacuum robot 26, which is moved up and down by an elevator 28 via a bellows 27 so that it can be moved up and down.
Wafers can be transferred from the load lock chamber 2 to the wafer storage chamber 5 or from the wafer storage chamber 5 to the load lock chamber 2 at a predetermined height without breaking the vacuum. After that, the atmosphere is released in the load lock chamber 2.

FIG. 5 shows the structure of the vacuum storage according to the second embodiment of the present invention. Two vacuum storage chambers 5 on both sides of the robot chamber 3
Is connected. This is effective when the number of stored wafers increases or when it is necessary to separately store wafers that may cause mutual contamination when stored in the same vacuum storage chamber.

FIG. 6 shows the structure of the vacuum storage according to the third embodiment of the present invention. In this embodiment, the wafer storage shelves 11 are arranged in two rows, and the robot chambers 3 are provided on both sides. This is especially effective when the number of wafers stored is large. FIG. 7 shows the structure of the vacuum storage according to the fourth embodiment of the present invention. This is a combination of the second and third embodiments to increase the number of stored sheets. As can be seen from these examples, the storage cabinet of this system can meet various requests by various combinations of standardized constituent elements according to the number of stored sheets. Further, in these embodiments, the number of wafer shelves in one row is three, but the number is not limited to this. Also, the number of rows is two in the third embodiment, but there is no problem if more rows are used.

In each of the above-described embodiments, the wafer 5 is placed in the load lock chamber 2 under atmospheric pressure, is vacuum-stored, and is taken out again after storage under atmospheric pressure. In the fifth embodiment of the present invention shown in FIG. 8, the load lock chamber is removed and the robot chamber 3 is directly connected to the vacuum tunnel type transfer device 27. This vacuum tunnel type transfer device is described in detail in, for example, International Patent Application PCT / JP93 / 009930. With this combination, the wafer is transferred under vacuum in a vacuum tunnel to a storage, and then transferred to a vacuum storage chamber and stored under vacuum while maintaining the vacuum. And when transferring to a vacuum process equipment,
While the vacuum is maintained, it is transferred from the vacuum storage chamber to the vacuum tunnel, and is transferred to the vacuum processing device while maintaining the vacuum by the magnetic levitation transfer device in the vacuum tunnel. Therefore, it is possible to store the vacuum device in a vacuum atmosphere without being exposed to the atmosphere between the vacuum devices. In this example, a vacuum tunnel is used as the transfer device,
The same effect can be obtained by using a vacuum carrier described in detail in Japanese Patent Application No. 62-131441.

Further, although the inside is a vacuum in the above examples,
The storage cabinet of each of the above-described embodiments can be used not only in a vacuum but also in the interior of an inert gas such as nitrogen or air having a very low water content. As described above, various modifications can be made without departing from the spirit of the present invention. The same reference numerals in the drawings indicate the same or corresponding constituent elements.

[0024]

The vacuum storage is divided into a load lock chamber, a robot chamber, and a vacuum storage chamber, which are connected to each other through a gate valve, and the vacuum storage chamber has a wafer storage rack (transport carriage) which can be linearly moved. ), The wafer can be transferred while the storage chamber is kept in a vacuum state. In addition, the mechanical contact portion can be eliminated by linearly moving the storage shelf while it is magnetically levitated. Therefore, a vacuum storage for wafers having an extremely high degree of cleanliness was realized.

[Brief description of drawings]

FIG. 1 shows a configuration of a storage cabinet according to a first embodiment of the present invention,
(A) is a top view, (B) is a sectional view taken along the line CC of (A).

2A is a top view, FIG. 2B is a vertical sectional view, and FIG. 2C is a horizontal sectional view.

FIG. 3 is a cross-sectional view showing a drive mechanism of a storage shelf in the vacuum storage chamber in FIG.

4 is a cross-sectional view showing another example of the drive mechanism of the storage rack in the vacuum storage chamber in FIG.

FIG. 5 shows a configuration of a storage cabinet according to a second embodiment of the present invention,
(A) A top view, (B) A sectional view taken along the line CC of (A).

FIG. 6 is a top view showing the configuration of the storage cabinet according to the third embodiment of the present invention.

FIG. 7 is a top view showing the configuration of the storage cabinet according to the fourth embodiment of the present invention.

FIG. 8 is a top view showing the configuration of the storage cabinet according to the fifth embodiment of the present invention.

FIG. 9 is a perspective view showing the configuration of a conventional storage cabinet.

[Explanation of symbols]

 1 Vacuum Storage 2 Load Lock Chamber 3 Robot Room 5 Vacuum Storage Chamber 6, 7 Gate Valve 9 Vacuum Exhaust System 10 Clean Air (Gas) Supply Source 11 Storage Shelf 12 Wafer 13 Magnetic Material 14 Conductor

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H01L 21/68 TA (72) Inventor Masao Matsumura 4-2-1 Honfujisawa, Fujisawa-shi, Kanagawa Stock company (72) Inventor Takeshi Yoshioka 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Incorporated EBARA Research Institute

Claims (5)

[Claims] 1. A vacuum storage for storing an object to be stored in a vacuum atmosphere, the vacuum storage comprising a vacuum storage chamber, a robot chamber, and a load lock chamber, each of which is provided with a gate valve. A vacuum storage cabinet, which is airtightly connected to the storage container and has means for holding the vacuum of the vacuum storage chamber even when the storage object is transferred. 2. The vacuum storage chamber is provided with a storage rack for storing the horizontally movable object to be stored, and a drive mechanism for the storage rack, and the robot chamber stores the object to be stored in a horizontal plane. The vacuum storage cabinet according to claim 1, further comprising a robot that vertically transfers the robot. 3. The vacuum storage cabinet according to claim 2, wherein the storage rack is levitationally supported by a magnetic levitation transfer device from the partition wall of the vacuum storage chamber in a non-contact manner. 4. The magnetic levitation transfer apparatus comprises a levitation electromagnet and a linear motor arranged outside the partition wall of the vacuum storage chamber, and the storage rack is levitated by a magnetic attraction force of the levitation electromagnet to obtain the linear motor. 4. The vacuum storage cabinet according to claim 3, wherein the vacuum storage chamber is moved horizontally in accordance with. 5. The magnetic levitation transfer apparatus comprises a levitation electromagnet and a moving means for the levitation electromagnet outside the partition wall of the vacuum storage chamber, and the storage rack is levitation by the magnetic attraction force of the levitation electromagnet to obtain the levitation electromagnet. The vacuum storage cabinet according to claim 3, wherein the storage rack in the vacuum storage chamber is moved in the horizontal direction by moving the vacuum storage chamber.