WO2010089460A1

WO2010089460A1 - Gate arrangement, production line and method

Info

Publication number: WO2010089460A1
Application number: PCT/FI2010/050079
Authority: WO
Inventors: Pekka Soininen; Jarmo Skarp
Original assignee: Beneq Oy
Priority date: 2009-02-09
Filing date: 2010-02-08
Publication date: 2010-08-12
Also published as: FI20095125A; CN102308023A; FI20095125A0; FI122880B

Abstract

The invention relates to a gate arrangement (10, 11) through which a substrate (8) may be introduced into a process chamber (4) and/or removed from the process chamber (4), the gate arrangement (10, 11) comprising a separating valve (12, 22) through which the substrate (8) is led into the process chamber (4) and/or removed from the process chamber (4). In accordance with the invention, the gate arrangement (10, 11) comprises in connection with the separating valve (12, 22) at least one diffusion gate (14, 16, 24, 26) which the substrate (8) substantially obstructs while passing through the gate arrangement (10, 11), when it is fed into and/or removed from the process chamber (4). The invention also relates to a production line including the gate arrangement (10, 11) and to a method for introducing the substrate (8) into the process chamber (2, 4, 6) and for removing it therefrom.

Description

GATE ARRANGEMENT, PRODUCTION LINE AND METHOD

BACKGROUND OF THE INVENTION

[0001] The invention relates to a gate arrangement, and in particular to a gate arrangement in accordance with the preamble of claim 1 , through which a substrate may be introduced into a process chamber and/or removed from the process chamber, the gate arrangement comprising a separating valve, through which the substrate is introduced into a process chamber and/or removed from the process chamber. The invention also relates to a production line, and in particular, to a production line in accordance with the preamble of claim 15, which comprises two or more successive process units for modifying and/or growing of a substrate surface, of which process units at least one comprises a process chamber, in which production line at least one of the process chambers is separated from a preceding and/or subsequent process unit with a gate arrangement comprising a separating valve and through which the substrate may be introduced into and/or removed from the process chamber. The invention further relates to a method in accordance with the preamble of claim 31 for introducing the substrate into and/or removing it from the process chamber through the gate arrangement.

[0002] Typical ALD reactors are independent reactors, in which one or more substrates are loaded into the reaction chamber of the reactor. The ALD reactors include a low-pressure chamber and thereinside a separate reaction chamber, or alternatively, the low-pressure chamber also serves as the reaction chamber and thus no separate reaction chamber is needed. In that case, when a substrate is loaded into the reactor and removed therefrom, the low-pressure state of the low-pressure chamber must be destroyed. Conventionally, this problem is solved by a load-lock provided in the ALD reactor, which allows a movable reaction chamber and/or substrate treatment at normal ambient pressure. In semiconductor industry this problem relating to destruction of low pressure in the reactor has been solved by using a specific cluster tool for treating the substrate. This cluster tool is used in loading substrates into and removing them from various process units, which have been connected thereto with gate valves. In connection with the cluster tool, a large robot is placed in a robot chamber where low pressure prevails. The robot chamber may be further connected to the ALD reactor and to a chemical vapour deposition line. [0003] The prior art cluster tools as described above are large and expensive appratuses. In addition, it is impossible to use them efficiently in production lines employed in mass production. Semiconductor products, such as solar panels, are therefore manufactured cost-effectively on production lines comprising successively positioned process chambers, in which a substrate surface is modified or a material layer is deposited thereon by a known chemical vapour deposition method, such as vaporization by CVD, or sputtering. On the production line the substrate moves onwards from one process chamber to the next in order for a multilayer product to be manufactured. There has not existed any simple solution to place an ALD reactor in a production line of this kind such that the production line could operate efficiently and that the ALD reactor could be connected to process chambers operating at different pressures or to other parts of the line. Therefore, it has not been possible to connect an ALD unit, for instance, to a production line of solar cells for mass production of solar cells.

BRIEF DESCRIPTION OF THE INVENTION

[0004] The object of the invention is to provide a gate arrangement, a production line and a method, by which the above problems may be solved. The object of the invention is achieved by a gate arrangement in accordance with the characterizing part of claim 1 , which is characterized in that the gate arrangement comprises in connection with a separating valve at least one diffusion gate which the substrate substantially blocks while passing through the gate arrangement, when it is introduced into and/or removed from the process chamber. The object of the invention is further achieved by a production line in accordance with the preamble of claim 15, which is characterized in that the gate arrangement is provided, in connection with the separating valve, with at least one diffusion gate which the substrate substantially blocks while passing through the gate arrangement, when it is introduced into and/or removed from the process chamber. The object of the invention is further achieved by a method in accordance with the characterizing part of claim 31 , which is characterized in that in the method the substrate is passed through the gate arrangement comprising a separating valve and a diffusion gate provided on at least one side thereof, whereby in the method the substrate is guided through the gate arrangement such that the substrate substantially blocks the gate ar- rangement while passing through the separating valve, when the substrate is introduced into and/or removed from the process chamber.

[0005] Preferred embodiments of the invention are disclosed in the dependent claims.

[0006] The invention is based on the idea that, in an atomic layer deposition reactor (ALD reactor), chemical vapour deposition reactor or the like, the gate or loading arrangement of a reaction chamber, low-pressure chamber or process chamber, through which a substrate may be introduced into the reactor, and in particular, into its low-pressure chamber, is provided with at least one specific diffusion gate, which is positioned on either one side of the gate. In some embodiments, the process chamber may be provided with a diffusion gate on both sides of the gate. The diffusion gate is provided such that is comprises an aperture, gap or the like, through which the substrate passes. The aperture of the diffusion gate is dimensioned and shaped to correspond to the shape of the substrate to be fed therethrough such that the substrate substantially closes or blocks the aperture while passing therethrough. In other words, the aperture is such that it only just allows the substrate to pass therethrough, and between the inner walls of the aperture and the outer surface of the substrate there will be formed only such a small clearance that the substrate is able to pass through the aperture. Thus, a diffusion gate of this kind forms together with the substrate a valve, which closes when the substrate is in the aperture, whereby gas flow through the aperture of the diffusion gate is substantially obstructed.

[0007] The diffusion gate in accordance with the invention may be provided on both sides of the gate of the ALD reactor or another process chamber: inside and outside the low-pressure chamber. In particular, the diffusion gate is provided in connection with the separating valve of the process chamber, through which the substrate is loaded into and/or removed from the process chamber, such that a diffusion gate will be located on either side of the separating valve. Thus, when the substrate is loaded into the process chamber, the substrate goes first to the diffusion gate locating in front of the separating valve, outside the process chamber of the reactor, blocking or closing the aperture thereof and thus substantially obstructing the gas flow through the diffusion gate. Thereafter, the separating valve is opened and the substrate is passed onwards through the separating valve and it goes to the diffusion gate on the other side of the separating valve inside the process chamber closing or blocking the aperture thereof and thus substantially obstructing the gas flow. At the same time, the substrate exits the diffusion gate in front of the separating valve, outside of the process chamber. When the substrate as a whole has passed the separating valve, but is still blocking the diffusion gate inside the process chamber, the separating valve is closed. Thereafter, the substrate may be further conveyed onwards completely through the diffusion gate inside the process chamber. In an alternative embodiment, the diffusion gate is provided only inside or outside the process chamber with respect to the separating valve.

[0008] The diffusion gate in accordance with the present invention enables a simple and effective arrangement for introducing the substrate into the process chamber and removing it therefrom. Further, the present invention enables the process chamber to be placed in a production line comprising units operating at different pressures. Hence, by means of the gate in accordance with the invention the substrate may be conveyed through the process chamber, when the gates of the invention are provided on the opposite sides of the reactor. The gate in accordance with the present invention is also simple to manufacture and it enables the use of the ALD method and corresponding deposition methods, such as CVD, in mass production of products.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In the following the invention will be described in greater detail in connection with preferred embodiments, with reference to the attached drawings, in which Figures 1 to 7 show an embodiment of the present invention in connection with a production line.

DETAILED DESCRIPTION OF THE INVENTION

[0010] With reference to Figure 1 , it shows schematically a production line, where a substrate is conveyed through successive process chambers 2, 4, 6. In each process chamber the substrate 8 or its surface is modified, or a material layer is deposited on the surface of the substrate 8. The production line of this type may be employed, for instance, for manufacturing solar panels, semiconductor components or the like products. These products generally consist of two or more thin, material layers, which are deposited superimposed. Successive process chambers may comprise various coating processes, such as vaporization, CVD, ALD₁ sputtering et cetera, by means of which the surface of the substrate 8 will be modified or a material layer may be deposited thereon. In a production line of this kind different process chambers 2, 4, 6 often operate at different pressures, and therefore they must be separated from one another in a gas-tight manner, so that no gas exchange will take place between the process chambers. On the production line the substrate 8 passes from one process chamber 2, 4, 6 to another consecutively, whereby the process chambers 2, 4, 6, in particular, must be mutually separated in a gas-tight manner such that no gas exchange will take place between the process chambers as the substrate 8 is transferred from the process chamber 2, 4, 6 to the next one.

[0011] The embodiment of Figures 1 to 7 shows a solution in accordance with the invention, in which a planar or plate-like substrate 8 is conveyed from a first process chamber 2 to a second process chamber 4 and further to a third process chamber 6, i.e. the substrate 8 moves from left to right in Figures 1 to 7. The successive process chambers 2, 4, 6 are separated from one another with gate arrangements 10, 11 , through which the substrate 8 is passed, when it is transferred from one process chamber 2, 4, 6 to the next. In the production line of Figures 1 to 7, the second process chamber 4 may be, for instance, an atomic layer deposition chamber (ALD chamber), where the substrate 8 is modified by means of the atomic layer deposition method. The process chambers 2 and 6 may be CVD (Chemical Vapour Deposition) chambers, sputtering chambers, ALD chambers or other corresponding process chambers. It is to be noted, however, that the present invention is not limited to any particular process unit, but the production line may comprise any process units for treating the substrate. The first gate arrangement 10 of the invention between the first process chamber 2 and the ALD chamber 4 comprises a first separating valve 12, which may be, for instance, a gate valve or the like, and diffusion gates 14, 16 provided in connection with the first separating valve 12 on both sides thereof. The first diffusion gate 14 may be provided in front of the first separating gate 12 in the travel direction of the substrate 8, i.e. on the side of the first process chamber 2. Correspondingly, the second diffusion gate 16 is provided behind the first separating valve 12 in the travel direction of the substrate 8, i.e. on the side of the ALD chamber 4. The first diffusion gate 14 may be placed, or it may extend, at least partly inside the first process chamber 2. The second diffusion gate 16, in turn, may be placed, or it may extend, at least partly inside the ALD chamber 4 or the low-pressure chamber thereof. In that case the first diffusion gate 14 is placed, or it extends at least partly, outside of the ALD chamber 4.

[0012] The second gate arrangement 11 of the invention between the ALD chamber 4 and the process chamber 6 comprises a second separating valve 22, which may be, for instance, a gate valve or the like, and diffusion gates 24, 26 provided in connection with the separating valve 22 on both sides thereof. A third diffusion gate 24 is provided in front of the second separating valve 22 in the travel direction of the substrate 8, i.e. on the side of the ALD chamber 4. Correspondingly, a fourth diffusion gate 26 is provided behind the separating valve 22 in the travel direction of the substrate 8, i.e. on the side of the third process chamber 6. The third diffusion gate 24, in turn, may be placed, or it may extend, at least partly inside the ALD chamber 4. The fourth diffusion chamber 26 may be placed, or it may extend, at least partly inside the third process chamber 6. In that case, the fourth diffusion gate 26 is placed, or it at least partly extends, outside of the ALD gate 4.

[0013] In accordance with the above, the gate arrangement 10, 11 of the present invention comprises a separating valve 12, 22 and in connection with the separating valve 12, 22, on the opposite sides of the ALD chamber 4, a diffusion gate 14, 16, 24, 26. Each diffusion gate 14, 16, 24, 26 comprises an aperture, gap or the like 18, 20, 28, 30, through which the substrate is conveyed. The aperture 18, 20, 28, 30 of the diffusion gate 14, 16, 24, 26 is dimensioned and shaped according to the substrate 8 to be fed therethrough such that, while passing through the aperture, the substrate 8 substantially closes or blocks the aperture 18, 20, 28, 30. Hence, as the substrate 8 substantially closes the aperture 18, 20, 28, 30, a gas flow through the diffusion gate 14, 16, 24, 26, and consequently also through the gate arrangement 10, 11 , is obstructed. In other words, the aperture 18, 20, 28, 30 of the diffusion gate 14, 16, 24, 26 is provided such that there is only just space for the substrate to pass therethrough. Thus, a clearance or gap between the exterior of the substrate 8 and the aperture 18, 20, 28, 30 is to be provided as small as possible, however, such that the substrate 8 is able to pass through the aperture. The clearance between the exterior of the substrate 8 and the aperture 18, 20, 28, 30 is preferably smaller than, substantially equal to, the mean free travel of a molecule. The present invention works best, when the substrate 8 has a substantially uniform cross section in its travel direction. In other words, the substrate 8 is preferably in the form of a plate, plane, bar, tube or thread such that its shape and dimensions remain substantially uniform in its longitudinal direction or travel direction, in which it passes through the gate arrangement 10, 11. When the substrate 8 used is in the form of a plate or plane, the shape of the aperture 18, 20, 28, 30 is substantially rectangular, or in the form of an elongated gap, in accordance with the substrate's 8 cross section, seen perpendicularly to its travel direction. Alternatively, the aperture 18, 20, 28, 39 may be round or oval, a tiny hole or the like, corresponding to the cross section of the substrate 8 in the direction perpendicular to its travel direction such that the substrate only just fits through the aperture 18, 20, 28, 30.

[0014] The diffusion gate 14, 16, 24, 26 may be provided at least partly as a tubular and sleeve-like part or a collar that is provided in connection with the separating valve 12, 22, or that is mounted or attached to the separating valve 12, 22 in accordance with Figure 1. The cross-sectional area of this tubular or sleeve-like diffusion gate may taper from the separating valve 12, 22 towards the aperture 18, 20, 28, 30. In other words, the diffusion gate 12, 22, or the aperture 18, 20, 28, 30 therethrough, may taper away from the separating valve 12, 22. In an embodiment the diffusion gate 18, 20, 28, 30 may be provided as a cam pipe tapering away from the separating valve 12, 22. Alternatively, the diffusion gate 18, 20, 28, 30 may be formed to be a straight and even plate-like part which is provided in connection with the separating valve. The plate-like diffusion gate 18, 20, 28, 30 may comprise a simple hole, through which the substrate is conveyed, or it may be provided with a tubular or sleeve-like opening having a cross-sectional area tapering away from the separating valve 12, 22 or a cross-sectional area that remains constant. In other words, in this embodiment in a planar, straight plate there is provided a tubular or sleeve-like part protruding outwardly from it surface. The length of the above tubular or sleeve-like diffusion gate 14, 16, 24, 26 or its tubular or sleeve-like opening is in a preferred case substantially equal to or larger than the free travel of a molecule, whereby molecule flow through the diffusion gate 14, 16, 24, 26 is prevented efficiently.

[0015] The gate arrangement 10, 11 in accordance with the present invention may be provided with suction means or other corresponding low- pressure means (not shown). These suction means are provided in connection with the separating valve 12, 22 and preferably between or in the space between the diffusion gates 14, 16, 24, 26 on the opposite sides thereof. Thus it is possible to provide in the gate arrangement 10, 11 low pressure or suction, by means of which the molecules which may have slipped through the diffusion gates 14, 16, 24, 26 into the gate arrangement are sucked away. There may be one or more suction means per one gate arrangement 10, 11. The suction means allow the gate arrangement 10, 11 to be provided with a diffusion gate flow, which further enhances the operation of the gate arrangement 10, 11.

[0016] Gate arrangements 10, 11 of the type described above may be employed in a production line to separate one or more process chambers 2, 4, 6 from one another. In that case the gate arrangements 10, 11 are provided on the opposite sides of the separating valve with a first and a second diffusion gate 14, 16, 24, 26, respectively, which the substrate substantially blocks while passing through the gate, when it is introduced into and/or removed from the process chamber 2, 4, 6. The diffusion gate corresponds in the production line to the above-described diffusion gate of a single process chamber 2, 4, 6. In the production line, the process chamber 2, 4, 6 comprises a gate arrangement advantageously on the opposite sides such that the product to be manufactured or modified on the production line may be conveyed through the process chamber 2, 4, 6.

[0017] Figures 1 to 7 show schematically a production line or a part thereof, which comprises a first process chamber 2, an ALD chamber 4 and a third process chamber 6. The ALD chamber 4 is separated from the first process chamber 2 by a first gate arrangement 10 and from the third process chamber 6 by a second gate arrangement 11. In the following, it is explained how a substrate is fed from the first process chamber 2 into the ALD chamber 4 and further from the ALD chamber 4 into the third process chamber 6.

[0018] In the situation of Figure 1 , the substrate 8 is conveyed by first transfer means 32 to an aperture 18 of a diffusion gate 14 locating in front of a first separating valve 12 of the first gate arrangement 10, or on the side of the process chamber 2, which aperture will be substantially closed or blocked by the substrate 8. In other words, the substrate 8 is inserted in the aperture 18 of the first diffusion gate 14, in front of the first separating valve 12, whereby gas will not be able to flow substantially through the first diffusion gate 14. The substrate 8 is preferably stopped to this position, whereafter the first separating valve 12 is opened and the substrate 8 is transferred, in accordance with Figure 2, through the first separating valve 12. The total length of the gate arrangement 10, in the travel direction of the substrate 8, is preferably such that before the propulsion of the transfer means 32 of the first process chamber ends the transfer means 34 of the ALD chamber 4 start pulling the substrate 8. In other words, the substrate 8 is conveyable through the first gate arrangement by the cooperation of the transfer means 32 of the first process chamber and the transfer means 34 of the ALD chamber 4, as both transfer means 32 and 34 are capable of transferring the substrate 8 simultaneously part of the travel as shown in Figure 2.

[0019] The transfer of the substrate 8 into the ALD chamber 4 is continued, until the substrate 8 has passed completely through the first separating valve 12 to the position shown in Figure 3, where the substrate 8 is in the aperture 20 of the second diffusion gate 16 of the first gate arrangement 10, i.e. the one on the side of the ALD chamber 4, such that it substantially obstructs or closes the aperture 20 preventing the gas from flowing through the first gate arrangement 10. The substrate 8 may be stopped to this position, where it has travelled through the first separating valve 12, but is still inside the second diffusion gate 16. The first separating valve 12 is then closed, whereafter the substrate 8 is further transferred completely through the second diffusion gate 16 into the ALD chamber 4 to a position shown in Figure 4, where it may be treated in accordance with the ALD method.

[0020] After depositing a material layer on the surface of the substrate 8 or after modifying the surface of the substrate 8 by the ALD method, the substrate 8 is transferred with the transfer means 34 of the ALD chamber to a position shown in Figure 5, inside the aperture 28 of the third diffusion gate 24 of the second gate arrangement 11 , on the side of the ALD chamber 4, in front of the second separating valve 22. In that case the substrate 8 substantially closes or blocks the third diffusion gate 24 such that gas will not be able to flow substantially therethrough. The substrate 8 is stopped to this position shown in Figure 5 and the second gate valve 22 is opened. Thereafter, the substrate 8 is further conveyed onwards through the second gate valve 22 by the transfer means 34 of the ALD chamber 4, until the substrate 8 attains the transfer means 36 of the third process chamber 6 as shown in Figure 6. In the position as shown in Figures 2 and 6 the substrate 8 substantially extends through the separating valve 12, 22 and the diffusion gates 14, 24, 16, 26 on both sides thereof. From the position of Figure 6 the substrate 8 is further transferred onwards by the transfer means 34 of the ALD chamber 4 and by the transfer means 36 of the third process chamber 6, until the substrate 8 has moved towards the third process chamber 6 such that its transfer onwards is continued only by means of the transfer means 36 of the third process chamber 6. In this manner the substrate 8 is transferred to a position shown in Figure 7, where it has passed completely through the second separating gate 22, but is still inside the aperture 30 of the fourth diffusion gate 26, substantially obstructing the gas flow. The substrate 8 is stopped again to a position shown in Figure 7, when it has exited the second separating valve 22, whereafter the second separating valve 22 is closed. Thereafter, the substrate 8 may be transferred completely through the fourth diffusion gate 26 inside the third process chamber 6. The transfer means 32, 34, 36 may be conveyor rolls, a conveyor belt or the like, on which the substrate 8 may be transferred.

[0021] Even though it is described above that the substrate 8 is stopped before the separating valves 12, 22, the substrate 8 being, in its travel direction, inside the diffusion gate 14, 24 in front of the separating valve, this is not necessary, however. The operation of the separating valves 12, 22 may be automated such that the separating valves 12, 22 open as the substrate 8 arrives, in the travel direction of the substrate 8, in the diffusion gate 14, 24 in front of the separating valves 12, 22, and close as the substrate 8 has passed through the separating valve 12, 22, but is still inside the diffusion gate 16, 26 behind the separating valve 12, 22 in the travel direction of the substrate 8. In addition, the operation of the above-described suction means may be automated such that the suction means operate when the substrate is inside the gate arrangement or when the separating valve is open.

[0022] For the gate arrangement of the present invention to operate efficiently the substrate 8 always extends inside at least either one of the diffusion gates 14, 16, 24, 26 of the gate arrangement 10, 11 when the separating valve 12, 22 is open such that the substrate 8 together with the diffusion gate 14, 16, 24, 26 obstructs the gas flow. The gate arrangement of the invention may also be employed in a separate process chamber that is not placed in the production line. In addition, a separate process chamber or one placed in the production line may, in particular applications, be provided with just one gate arrangement 10, 11 of the invention, whereby the substrate 8 may be introduced into the ALD unit and be removed therefrom via the same gate arrangement 10, 11. Further, each gate arrangement may comprise just one diffusion gate 14, 16, 24, 26, which may be placed either inside or outside the process chamber with respect to the separating valve 12, 22. In this application the process chamber refers to any process chamber, in which the substrate 8 may be treated, such as coated or doped. The process chamber may be a low- pressure or a high-pressure chamber, or the process chamber may operate at normal atmospheric pressure (NTP, 1 bar, O⁰C).

[0023] The production line as described above may be used, for instance, for manufacturing solar cells, semiconductor components, flat glass products, metal/paper strips, threads, fibres or other products that are modified and coated with the ALD method. Moreover, it should be noted that a production line of this kind may also comprise more than one ALD chambers. Further, the gate in accordance with the invention may also be utilized in connection with chambers other than ALD chambers. In other words, the gate arrangement of the invention may be utilized in connection with all chambers whose inside pressure differs from ambient pressure or which otherwise are to be isolated from the environment. The simple gate arrangement in accordance with the invention offers a particular advantage by allowing a simple manner to separate from one another process chambers or process units operating at different pressures such that no substantial gas exchange will take place between the process units.

[0024] It is obvious to a person skilled in the art that as technology advances the basic idea of the invention may be implemented in a variety of ways. Thus, the invention and the embodiments thereof are not restricted to the above examples, but they may vary within the scope of the claims.

Claims

1. A gate arrangement (10, 11), through which a substrate (8) may be introduced into a process chamber (4) and/or removed from the process chamber (4), the gate arrangement (10, 11) comprising a separating valve (12, 22), through which the substrate (8) is introduced into the process chamber (4) and/or removed from the process chamber (4), characterized in that the gate arrangement (10, 11) comprises in connection with a separating valve (12, 22) at least one diffusion gate (14, 16, 24, 26) which the substrate (8) substantially blocks while passing through the gate arrangement (10, 11), when it is introduced into and/or removed from the process chamber (4).

2. The gate arrangement (10, 11 ) of claim 1, characterized in that the gate arrangement (10, 11) comprises a diffusion gate (14, 16, 24, 26) inside or outside the process chamber (4) in relation to the separating valve (12, 22).

3. The gate arrangement (10, 11 ) of claim 1, characterized in that the gate arrangement (10, 11) comprises, in relation to the separating valve (12, 22), a first diffusion gate (14, 26) outside the process chamber (4) and a second diffusion gate (14, 24) inside the process chamber (4).

4. The gate arrangement (10, 11 ) of any one of the preceding claims 1 to 3, characterized in that the diffusion gate (14, 16, 24, 26) comprises an aperture (18, 20, 28, 30) for conveying the substrate (8) via the diffusion gate (14, 16, 24, 26) through the separating valve (12, 22), the shape and dimensions of the aperture (18, 20, 28, 30) corresponding substantially to the shape and dimensions of the substrate (8) to be introduced into the process chamber (4) such that while passing through the aperture (18, 20, 28, 30) the substrate (8) substantially closes the aperture (18, 20, 28, 30).

5. The gate arrangement (10, 11 ) of claim 4, characterized in that the aperture (18, 20, 28, 30) of the diffusion gate (14, 16, 24, 26) is dimensioned such that while the substrate (8) passes in the aperture (18, 20, 28, 30) a gap between the outer surface of the substrate (8) and the inner surface of the aperture (18, 20, 28, 30) will be smaller than or substantially equal to the mean free travel of a molecule.

6. The gate arrangement (10, 11 ) of any one of the preceding claims 1 to 5, characterized in that the diffusion gate (14, 16, 24, 26) is tubular or sleeve-like.

7. The gate arrangement (10, 11 ) of claim 6, characterized in that the cross-sectional area of the tubular or sleeve-like diffusion gate (14, 16, 24, 26) reduces from the separating valve (12, 22) towards the aperture (18, 20, 28, 30).

8. The gate arrangement (10, 11 ) of claim 6 or 7, characterize d in that the diffusion gate (14, 16, 24, 26) is provided as a cam pipe tapering away from the separating valve (12, 22).

9. The gate arrangement (10, 11 ) of any one of the preceding claims 1 to 5, characterized in that the diffusion gate (14, 16, 24, 26) is plate- like.

10. The gate arrangement (10, 11 ) of claim 9, characterized in that the plate-like diffusion gate (14, 16, 24, 26) comprises a tubular or sleeve-like aperture (18, 20, 28, 30) having a cross-sectional area that reduces away from the separating valve (12, 22) or a cross-sectional area that remains constant.

11. The gate arrangement (10, 11) of any one of the preceding claims 4 to 10, characterized in that the aperture (18, 20, 28, 30) has a gap-like and rectangular shape such that it is arranged to receive a plate-like or planar substrate (8).

12. The gate arrangement (10, 11) of any one of the preceding claims 6 to 11, characterized in that the length of the tubular or sleeve- like diffusion gate (14, 16, 24, 26) or the tubular or sleeve-like aperture of the diffusion gate (14, 16, 24, 26) is substantially equal to or larger than the free travel of a molecule.

13. The gate arrangement (10, 11) of any one of the preceding claims 1 to 12, characterized in that the gate arrangement (10, 11) further comprises suction means provided in connection with the separating valve (12, 22) so as to produce a diffusion gate flow.

14. The gate arrangement (10, 11) of claim 13, characterized in that the suction means are provided to generate a diffusion flow in a space between the first and the second diffusion gates (14, 16; 24, 26).

15. A production line which comprises two or more successive process units for modifying and/or growing a substrate (8) surface, of which process units at least one comprises a process chamber (2, 4, 6), in which production line at least one of the process chambers (2, 4, 6) is separated from a preceding and/or subsequent process unit with a gate arrangement (10, 11) comprising a separating valve (12, 22) and through which the substrate (8) may be introduced into and/or removed from the process chamber (2, 4, 6), characterized in that the gate arrangement (10, 11 ) is provided in connection with the separating valve (12, 22) with at least one diffusion gate (14, 26, 24, 26) which the substrate (8) substantially blocks while passing through the gate arrangement (10, 11), when it is introduced into and/or removed from the process chamber (4).

16. The production line of claim 15, characterized in that the gate arrangement (10, 11) comprises the diffusion gate (14, 16, 24, 26) inside or outside the process chamber (2, 4, 6) in relation to the separating valve (12, 22).

17. The production line of claim 15, characterized in that the gate arrangement (10, 11) comprises, in relation to the separating valve (12, 22), a first diffusion gate (14, 26) outside the process chamber (2, 4, 6) and a second diffusion gate (14, 24) inside the process chamber (2, 4, 6).

18. The production line of claim 15, characterized in that the gate arrangement (10, 11) comprises, on the opposite sides of the separating valve (12, 22), a first and a second diffusion gate (14, 16, 24, 26), respectively, which the substrate (8) substantially blocks while passing through the gate arrangement (10, 11), when it is introduced into and/or removed from the process chamber (2, 4, 6).

19. The production line of any one of claims 15 to 18, character i z e d in that the process chamber (2, 4, 6) comprises the gate arrangement (10, 11), on two opposite walls thereof, such that the substrate (8) is con- veyable on the production line through the process chamber (2, 4, 6).

20. The production line of any one of claims 15 to 19, character i z e d in that the production line comprises transfer means (32, 34, 36), by means of which the substrate (8) is transferred within the process chambers (2, 4, 6) and between the process units.

21. The production line of claim 20, characterized in that the gate arrangement (10, 11 ) is provided such that the substrate (8) is conveyable through the gate arrangement (10, 11) utilizing the transfer means (32, 34, 36) of both the process chamber (2, 4, 6) and the preceding or subsequent process unit.

22. The production line of any one of claims 15 to 21, character i z e d in that the substrate (8) is arranged to obstruct the diffusion gate (14, 16, 24, 26) such that in the diffusion gate (14, 16, 24, 26) a clearance between the substrate (8) and the diffusion gate (14, 16, 24, 26) is smaller than or substantially equal to the mean free travel of a molecule.

23. The production line of any one of claims 15 to 22, c h a ra c- t e r i z e d in that the diffusion gate (14, 16, 24, 26) is tubular or sleeve-like.

24. The production line of claim 23, characterized in that the cross-sectional area of the tubular or sleeve-like diffusion gate (14, 16, 24, 26) reduces from the separating valve (12, 22) towards the diffusion gate (14, 16, 24, 26).

25. The production line of any one of claims 15 to 22, c h a ra c- t e r i z e d in that the diffusion gate (14, 16, 24, 26) is plate-like.

26. The production line of claim 25, characterized in that the plate-like diffusion gate (14, 16, 24, 26) comprises a tubular or sleeve-like aperture (18, 20, 28, 30) having a cross-sectional area that reduces away from the separating valve (12, 22) or a cross-sectional area that remains constant.

27. The production line of any one of claims 15 to 26, c h a r a c- t e r i z e d in that the diffusion gate (14, 16, 24, 26) has a gap-like and rectangular shape such that it is arranged to receive the plate-like or planar substrate (8).

28. The production line of any one of claims 23, 24, 26 or 27, characterized in that the length of the tubular or sleeve-like diffusion gate (14, 16, 24, 26) or the tubular or sleeve-like aperture of the diffusion gate (14, 16, 24, 26) is substantially equal to or larger than the free travel of a molecule.

29. The production line of any one of claims 15 to 28, c h a ra c- terized in that the gate arrangement (10, 11) is provided with suction means so as to produce a diffusion gate flow in the gate arrangement (10, 11 ).

30. The production line of any one of claims 15 to 29, c h a ra c- t e r i z e d by being a production line for manufacturing solar cells.

31. A method for introducing a substrate (8) into a process chamber (4) and/or for removing it therefrom through a gate arrangement (10, 11), characterized in that in the method the substrate (8) is conveyed through the gate arrangement (10, 11), which comprises a separating valve (12, 22) and a diffusion gate (14, 16, 24, 26) provided on at least one side thereof, whereby in the method the substrate (8) is led through the gate arrangement (10, 11) such that the substrate (8) substantially blocks the diffusion gate (14, 16, 24, 26) while passing through the separating valve (12, 22) when the substrate (8) is introduced into and/or removed from the process chamber

(4).

32. The method of claim 31, characterized in that the gate arrangement comprises diffusion gates (14, 16, 24, 26) provided on the opposite sides of the separating valve (12, 22), whereby the method comprises the steps of conveying the substrate (8) in its travel direction into an aperture (18, 28) of the first diffusion gate (14, 24) of the gate arrangement (10, 11), which aperture the substrate (8) substantially closes; opening the separating valve (12, 22) while the substrate (8) still substantially closes the aperture (18, 28) of the first diffusion gate (14, 24); conveying the substrate (8) onwards through the separating valve (12, 22) in the travel direction of the substrate (8) to an aperture (20, 30) of a second diffusion gate (16, 26) behind the separating valve (12, 22), which aperture the substrate (8) substantially closes and the separating valve (12, 22) is closed, and conveying the substrate (8) out of the aperture (20, 30) of the second diffusion gate (16, 26) in the travel direction of the substrate.

33. A method of claim 32, characterized by stopping the motion of the substrate (8) prior to opening the separating valve (12, 22), the substrate (8) being, in its travel direction, in the aperture (18, 28) of the first diffusion gate (14, 24) and/or stopping the motion of the substrate (8) prior to closing the separating valve (12, 22), the substrate (8) being, in its travel direction, in the aperture (20, 30) of the second diffusion gate (16, 26).

34. The method of any one of the preceding claims 31 to 33, characterized by generating a diffusion gate flow in the gate arrangement (10, 11 ) by means of suction means.

35. The method of any one of the preceding claims 31 to 34, characterized in that the method is employed in a production line for introducing the substrate (8) into an atomic layer deposition unit (4) and/or removing it therefrom.

36. The method of any one of the preceding claims 31 to 35, characterized in that the method is employed in a production line of solar cells.