WO2006071115A1

WO2006071115A1 - Lock enabling materials to be fed from and to a closed space in which a defined gas atmosphere is present, and a method for moving materials to a closed space with the aid of the lock

Info

Publication number: WO2006071115A1
Application number: PCT/NL2005/000895
Authority: WO
Inventors: Barteld Kolk; Fokko Pentinga; Ronald Gerardus Maria De Bruijn
Original assignee: Tempress Systems BV
Current assignee: Tempress Systems BV
Priority date: 2004-12-28
Filing date: 2005-12-23
Publication date: 2006-07-06
Anticipated expiration: 2007-06-28
Also published as: NL1027902C2

Abstract

Lock (1) allowing materials to be moved between two spaces (5, 6), with a different gas atmosphere prevailing in the two spaces. The lock (1) comprises two hollow cylinders (2, 11), each with an opening (14, 15) in the curved cylinder wall. One hollow cylinder (11) is positioned concentrically inside the first hollow cylinder (2), and the two cylinders can rotate independently of one another about the same axis of symmetry (3). The outer hollow cylinder is connected in an airtight manner to the partition (4) in which the lock is positioned, with the aid of sealing means (16). A small intermediate space (20) is present between the inner wall of the outer cylinder (2) and the outer wall of the inner cylinder (11). The invention also relates to a method for feeding materials from a dust-free space or clean room (6) to a closed space (5), via a lock.

Description

Lock enabling materials to be fed from and to a closed space in which a defined gas atmosphere is present, and a method for moving materials to a closed space with the aid of the lock

The invention relates to a lock which is used to enable materials to be fed from a first space to a closed second space and vice versa, the gas atmosphere in the second closed space having a different composition than the gas atmosphere in the first space, which lock is secured in a partition between the two spaces. The invention also relates to a method for feeding materials from a first space, such as a low-dust space (better known by the name clean room), to a closed or second space, via a lock according to the invention.

If materials are to be processed under a defined gas atmosphere which deviates from the composition of air, such as an atmosphere in which no oxygen or only a defined, very small quantity of oxygen may be present, the processing has to be carried out in a closed space, in which the desired gas atmosphere, for example nitrogen, is present. To ensure that the gas atmosphere in the treatment space does not have to be changed each time materials are introduced for treatment and each time treated materials are removed from the closed space, on account of ambient air having the opportunity to penetrate into the closed second space that has been temporarily opened on account of the fact that the space has to be opened to admit the materials, it is preferable for the materials to be introduced into the closed space via a lock, since the gas atmosphere of the smaller space of the lock can be changed more quickly than that of the closed second space. This is because without using a lock, the gas atmosphere of the much larger closed space has to be changed, which takes much more time and therefore also entails greater costs.

The lock serves to enable the gas atmosphere surrounding the materials to be processed to be changed. The materials are moved from ambient air into the open lock, with the atmosphere in the lock corresponding to the ambient air. Then, the lock is closed and the gas atmosphere in the lock is changed to the desired gas atmosphere, until the gas atmosphere approximately corresponds to the gas atmosphere of the closed space, after which the lock is opened on the side of the closed space. The material can then be treated and, after it has been treated, can be removed from the closed space again via the lock without the ambient air being able to penetrate into the closed space, and then the gas atmosphere can be adapted to the desired gas atmosphere.

Locks which are used to pass materials through to a closed space are generally known per se. These locks comprise a space which can be closed off on two sides by a closure member, such as a door or a slide. On both sides of the closed space, the means for closing the opening in the lock, such as a slide or a door, take up space, which needs to be reserved in particular in the closed space, even though it is not actually available, since the closed space always needs to be as small as possible. Japanese patent application 07.254635 has also disclosed a lock which comprises a cylinder with a single opening in the cylinder wall, which cylinder is rotatable in a cylindrical housing with two openings positioned opposite one another, by means of which lock materials, more specifically wafers, can be moved from one space to another while minimizing contamination to the gas atmosphere. However, the width of the feed opening is limited with respect to the inner surface area available on the rotatable cylinder.

It is an object of the invention to provide a lock which can be used for passing materials into and out of a space which is closed off in a gastight manner and is filled with a gas or gas mixture which deviates from air or ambient atmosphere, with the space taken up by the lock in both the closed and open position being no greater than the dimensions of the lock itself, with the result that firstly the space taken up by the lock is minimized with respect to the materials to be passed through, and moreover the surface area (footprint) taken up by the lock is also as small as possible. This is important because the costs of the space adjoining the closed space, such as a clean room, for which the locks according to the invention are used may be very high.

This object is achieved by the device according to the invention, by virtue of the fact that the lock comprises a first hollow cylinder, the walls of which comprise a curved cylinder surface, a base surface and a top surface, which are secured to one another in an airtight manner, and which hollow cylinder is provided with an opening in the curved cylinder wall, and which first hollow cylinder is secured, rotatably about its axis of symmetry, in the partition which separates the two spaces from one another, and by virtue of the fact that a second hollow cylinder is arranged concentrically inside the first hollow cylinder, which second cylinder is likewise secured rotatably about its axis of symmetry, which axis of symmetry coincides with the axis of symmetry of the first hollow cylinder, and which second cylinder can be rotated independently of the first cylinder, which second hollow cylinder is also provided with an opening in the cylinder wall.

On account of these measures, the use of the lock according to the invention has the advantage over the known locks that the space taken up by the lock according to the invention, both with regard to volume and surface area, is not much larger than that of the volume and surface area taken up by the materials to be passed through the lock, and the dimensions of the lock can be adapted accordingly. Moreover, if the opening in the outer wall of the outer cylinder is facing toward one side of the lock, access to the lock on the other side is automatically closed. Consequently, the lock according to the invention can never be opened simultaneously on both sides. A material or person lock which comprises two hollow cylinders, namely a second cylinder positioned in the first cylinder, is known per se from German utility model G 91,10,919.1. However, one of the cylinders is a fixed cylinder with two openings which are positioned diametrically opposite one another, while the other cylinder is provided with a single opening and can rotate about its axis of symmetry. To enable the gas atmosphere in the cylinder to be changed, the rotatable cylinder has to be completely closed. As a result, the opening for introducing and removing materials into and from the lock must always be smaller than one quarter of the circumference.

It is preferable for a small space to be present between the inner wall of the outer cylinder and the outer wall of the inner cylinder, with the result that no friction can occur between the two cylinders, since the occurrence of friction could lead to dust particles being released, and moreover if there is no friction it is easier for the two cylinders to rotate independently of one another.

To enable optimum use to be made of the volume of the lock for moving materials, in a preferred embodiment according to the invention the dimensions of the openings in the cylinder wall of both cylinders amount to approximately one quarter of the circumferential dimensions and approximately the height of the cylinder in question, with the result that it is easily possible to make use of the majority of the interior of the lock. Making the cylinder walls of both cylinders from transparent material makes it easier to look into the closed chamber from the outside.

The method for feeding materials from a first space, such as a dust-free space or clean room, to a closed or second space, via a lock according to the invention takes place as follows: first of all the two cylinders are positioned with the opening facing the surrounding space, while the gas pressure in the closed space is higher than the gas pressure of the first space out of which the materials are to be moved. Then, the materials which are to be passed through are placed into the inner cylinder of the lock. Next, the outer cylinder is rotated approximately half a revolution, specifically in such a manner that the opening of the outer cylinder faces toward the closed space while the opening of the inner cylinder remains facing the other side. Then, the gas is pumped out of the lock with the aid of means, with the result that gas from the closed second space is fed to the space enclosed by the two cylinders, and after it has been observed that the gas composition of the discharged gas corresponds to a sufficient extent to the gas composition of the gas located in the closed space, the second cylinder is then rotated approximately half a revolution, specifically in such a manner that the two openings of the two cylinders approximately coincide, and then the materials are removed from the lock and moved to a desired position inside the closed space. - A -

The invention will be explained in more detail with reference to the drawing, in which:

Figure 1 shows a cross section on line I - I from Figure 2 through the lock according to the invention;

Figure 2 shows a cross section on line II - II from Figure 1 through the lock according to the invention;

Figures 3 to 8 diagrammatically depict a cross section through a closed space and a lock according to the invention in a wall of the closed space.

Figures 1 and 2 show a lock 1 according to the invention. The lock 1 comprises a first hollow cylinder 2, which is arranged, rotatably about its axis of symmetry 3, in a partition 4 between two spaces 5 and 6 which are separate from one another, the first space 5 on one side of the partition 4 having a different gas atmosphere than the second space 6 on the other side of the partition 4. The cylinder 2 can rotate about its axis of symmetry 3 and comprises a cylindrically curved outer wall 7, and is delimited both at the top by a wall 8 and at the bottom by a wall 9, and both the top wall 8 and the bottom wall 9 are connected in a gastight manner to the cylinder wall 7.

A second cylinder 11, which can also rotate, independently of the first cylinder 2, about the same axis of symmetry 3, is arranged concentrically inside the space 10 enclosed by the first cylinder 2. The first cylinder 2 can be rotated with the aid of rotation means 12, for example an electric motor or pneumatic means, while independently of this the second cylinder 11 can also be rotated through a desired angle with the aid of rotation means 13. Both cylinders of each lock are provided with an opening 14, 15 in the cylinder wall. The outer cylinder of each lock is connected in an airtight manner to the partition 4, in which the lock is positioned, with the aid of sealing means 16. The sealing means 16 are preferably inflatable sealing means, with the result that the pressure on the sealing means can be reduced during the rotation of the outer cylinder, thereby minimizing the friction, since friction causes the formation of dust particles. The gas atmosphere can be discharged from the two cylinders of a lock via an outlet 17.

Figures 3, 4, 5, 6, 7 and 8 provide a highly diagrammatic illustration of a closed space 5, with two locks 1, namely a right-hand lock 18 and a left-hand lock 19 according to the invention, located in the partition 4 of the space, which separates the closed space from the space surrounding it. The method for passing materials through the lock will now be explained in more detail with reference to the figures. To enable what are known as wafers made from semiconductor material to be treated in a furnace, it is necessary for the materials to be transported from the furnace into a low-oxygen atmosphere. For this purpose, the space is placed, for example, under a very pure nitrogen atmosphere. To ensure that the atmosphere of the closed space 5 of the device does not have to be purified each time materials are moved into or out of the treatment space, and to minimize the dust particles in the atmosphere, use is made of a method in which the materials are first of all moved into a dust-free space, known as a clean room, where a normal gas atmosphere, i.e. air, is present, and which space is as far as possible free of dust. Then, the materials are moved out of the clean room into the closed treatment space via a lock.

Figure 3 diagrammatically depicts a closed space 5 with two locks 1 , namely a right-hand lock 18 and a left-hand lock 19, positioned in the wall of the space 5 adjacent to a first space (6), for example a clean room, the two cylinders 2, 11 of both locks 18, 19 being in the position in which the openings face toward the clean room 6, i.e. in such a manner that the inner cylinders 11 can be loaded with materials in order for these materials then to be passed through to the closed space 5 via the lock. The pressure of the gas atmosphere in the closed space must then be higher than the pressure of the gas atmosphere in the clean room, since otherwise during rotation of the cylinders there is a risk of oxygen-rich gas, namely the air from the clean room, being able to flow into the closed space, on account of the fact that during the rotation of the outer cylinder there is a risk that the space 5 will briefly be in direct contact with the air of the clean room, via the opening in the outer cylinder, or on account of the fact that the seal has been temporarily eliminated on the outer side of the outer hollow cylinder 2.

Figure 4 shows the closed space 5 with the two locks 18, 19, the outer cylinder 2 of the right- hand lock 18 having been rotated so that its opening faces toward the closed space. Next, nitrogen can flow out of the closed space into the space enclosed by the cylinders through the intermediate space 20 between the two cylinder walls of the lock 18. By sucking the gas atmosphere out of the cylinder and discharging it via an extraction system 21, the space inside the cylinder walls will be purged with nitrogen, and after a certain time the oxygen content of the atmosphere in the cylinder will have dropped to such an extent that it is below the desired percentage. Figure 5 then shows how the second lock 18 also has its outer cylinder rotated about its axis to such an extent that its opening likewise faces toward the closed space, and nitrogen is passed through both locks and discharged via the extraction system 21.

Figure 6 illustrates the position of the cylinders of the two locks 18, 19 after it has been measured that the oxygen content of the atmosphere has dropped sufficiently, so that the inner cylinder 11 can also be rotated half a revolution, and the openings of the two cylinders of both locks face the closed space, after which the materials can be removed from the lock and moved into the closed space to the desired position within the closed space 5. Now, it is also possible for the nitrogen to be recirculated continuously via the two locks 222 with the aid of a fan 23, via a filter 24, in order to enable as many dust particles as possible from the nitrogen atmosphere to be trapped. Figure 7 shows the position after materials from the closed space have been placed in the left- hand lock 19 and then the outer cylinder 2 has been rotated half a revolution. It is then possible for air from the clean room to be passed through the lock with the aid of the same extraction system 21, with the result that the pure nitrogen is discharged and the atmosphere inside the cylinders is changed to air. Figure 8 shows the left-hand lock 19 with the openings in both cylinders facing toward the clean room, with the result that the lock becomes accessible to a person allowing the materials to be removed from the lock and the lock to be reloaded if appropriate.

Claims

1. A lock (1) which is used to enable materials to be fed both from a first space (5) to a second space (6), which is sealed in a gastight manner, and in the opposite direction, wherein, by way of example, a gas atmosphere in the closed second space has a different composition than the gas atmosphere in the first space, which lock (1) is secured in a partition (4) between the two spaces and comprises a first or outermost hollow cylinder (2), the walls of which comprise a curved cylinder surface (7), a base surface (9) and a top surface (8), these surfaces (7, 8, 9) being connected to one another in an airtight manner, and a second or inner hollow cylinder (11), one of the walls of which is a curved cylinder surface, being arranged concentrically inside the first hollow cylinder (2), and the two hollow cylinders (2, 11) being provided with an opening (14, 15) in the cylinder wall, characterized in that both hollow cylinders (2, 11) are rotatable about their axis of symmetry (3), which first or outer hollow cylinder (2) is secured, rotatably about its axis of symmetry (3), in the partition (4) which separates the two spaces from one another, and can be connected in an airtight manner to the abovementioned partition (4) with the aid of sealing means (16), and which second or inner hollow cylinder (11) is secured inside the outer hollow cylinder (2) and can likewise rotate about its axis of symmetry (3), which coincides with the axis of symmetry of the first hollow cylinder (2), and which second cylinder can be rotated independently of the first cylinder, and in that both the first or outer hollow cylinder (2) is provided with a single opening (14) in the curved cylinder wall and the second or inner hollow cylinder (11) is provided with a single opening

(15) in the curved cylinder wall, and in that a small space (20) is present between the inner wall of the outer cylinder (2) and the outer wall of the inner cylinder (11).

2. The lock as claimed in claim 1, characterized in that the dimension of the opening in the cylinder wall of both cylinders covers a centre angle of between 80 and 150 degrees.

3. The lock as claimed in either of claims 1 and 2, characterized in that the sealing means

(16) for sealing the outer cylinder in an airtight manner with respect to the partition in which it is positioned is an inflatable seal.

4. The lock as claimed in one of claims I₅ 2 and 3, characterized in that the cylinder walls of both cylinders are made from transparent material.

5. A method for feeding materials from a first space, such as a dust-free space or clean room, to a closed or second space, via a lock as claimed in one of the preceding claims, characterized in that first of all the two cylinders (2, 11) are positioned with the opening facing the surrounding space (6), while the gas pressure in the closed or second space (5) is higher than the gas pressure of the first space (6) out of which the materials are being moved, in that then the materials which are to be passed through are placed into the inner cylinder (11) of the lock, then the outer cylinder (2) is rotated approximately half a revolution, specifically in such a manner that the opening of the outer cylinder (2) faces toward the closed space (5), then the gas from the lock is replaced, with the aid of means, by gas from the closed space, and after it has been observed that the gas composition of the gas discharged from the lock corresponds to a sufficient extent to the gas composition of the gas located in the closed space (5), only then is the second cylinder rotated approximately half a revolution, specifically in such a manner that the two openings of the two cylinders approximately coincide, and then the materials are removed from the lock and moved to a desired position inside the closed space (5).

6. The method as claimed in the preceding claim, characterized in that before the outer cylinder is rotated half a revolution, the seal (16) between the outer edge of the outer cylinder (2) and the wall in which the lock is positioned is partially eliminated, and the seal is restored again after the outer cylinder has rotated half a revolution.