WO2014191621A1

WO2014191621A1 - Substrate carrier and arrangement for supporting substrates

Info

Publication number: WO2014191621A1
Application number: PCT/FI2014/050418
Authority: WO
Inventors: Shuo Li; Olli Pekonen; Robin Enholm
Original assignee: Beneq Oy
Priority date: 2013-05-29
Filing date: 2014-05-27
Publication date: 2014-12-04

Abstract

The invention relates to a substrate carrier for holding substrates (2, 4) and to an arrangement for supporting substantially planar substrates (2, 4) during processing of the substrates (2, 4) by subjecting a surface (6, 8) of the substrate (2, 4) to successive surface reactions of at least a first precursor and a second precursor. The substrate carrier comprises two or more separate substrate holders (11, 14, 23) which are stacked against each other substantially in vertical direction, and that the substrate carrier further comprises rigid end plates (70, 72) such that the stacked separate substrate holders (11, 14, 23) are arranged between said rigid end plates (70, 72) and the rigid end plates (70, 72) are arranged to provide a pressing force for pressing the stacked separate substrate holders (11, 14, 23) against each other in vertical direction.

Description

SUBSTRATE CARRIER AND ARRANGEMENT FOR SUPPORTING SUBSTRATES

FIELD OF THE INVENTION

The present invention relates to a substrate carrier for holding substrates during processing of the substrates by subjecting a surface of the substrate to successive surface reactions of at least a first precursor and a second precursor, and particularly to a substrate carrier according to preamble of claim 1 . The present invention further relates to an arrangement for supporting substantially planar substrates during processing of the substrates by subjecting a surface of the substrate to successive surface reactions of at least a first precursor and a second precursor, and particularly to an arrangement according to preamble of claim 7.

BACKGROUND OF THE INVENTION

Atomic layer deposition (ALD) is generally known coating method in which surfaces of a substrate is subjected to alternating surface reactions of at least a first and a second gaseous precursor. One ALD-cycle is completed when the surfaces of the substrate are subjected once to both or all gaseous precursors. Each time the surface of the substrate is subjected to a precursor, a monolayer of material is formed on surfaces of the substrate. These ALD- surface reactions are normally substantially saturated surface reactions, meaning that the only one monolayer of material is formed on the surfaces of the substrate when the substrate is subjected to a precursor. One basic characteristic of ALD method is the conformality of the surfaces reactions. This means that the ALD growth layers of material grow on all the surfaces which are subjected to the precursors. Thus the coating is formed on all surfaces. In the present context the term atomic layer deposition also covers also atomic layer epitaxy (ALE) and other corresponding coating methods in which the material growth is based on successive substantially self-limiting surface reactions of at least two gaseous precursors.

However, in some applications it is undesirable to form the ALD- coating on all the surfaces of the substrate. For example it may be desirable to coat only one side of many planar or plate like substrates and the other side is left without coating. However, due to the excellent conformality of the ALD- method, the coating tends to grow on all the surfaces of the substrate and thus also on the side of the surface where it is undesirable. In prior art the undesirable coating on one side of a planar substrate is solved by etching or otherwise removing the coating from the substrate surface in which it is undesirable. However, etching or otherwise removing the coating from a substrate is difficult and time consuming. Furthermore, etching or otherwise removing the coating increases breakage rate of breakable or fragile substrates such as glass or silicon substrates.

Another prior art solution is to prevent coating formation on a predetermined portion of the surfaces of a substrate. The coating formation is prevented by placing the substrate against a support surface such that the surface of the substrate on which the coating formation is undesirable is placed against the support surface. The support surface may also be another substrate. In a case of substantially planar or plate-like substrates two substrates may be placed against each other for preventing coating formation on surfaces which are placed against each other. However, using a support surface or placing surface of a substrate against a support surface or a surface of another substrate has the disadvantage that it does not totally prevent coating formation. Furthermore, prior art substrate holders are rather large and the substrate cannot be positioned closely to each other and thus the number of substrate which may be processed in a reaction chamber at the same time is not adequate or optimal for efficient industrial solutions. In prior art solutions several substrates may be stacked on top of each other in vertical direction for forming a stack which is further arranged inside a reaction chamber for processing all the stacked substrate together at the same time. The stack may comprise the substrates and also the support surfaces or some other substrate supports. The problem with this prior art substrate arrangement in which substrates and substrate supports are stacked on top of each other is that the substrates at the bottom of the stack or at the lower part of the stack are subjected to weight of other substrates and other substrate supports of the upper part of the stack. The substrates, such as silicon wafers or plates, may be very fragile and thus the weight of the upper substrates and substrate supports may break fragile substrates at the lower part of the stack.

BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is to provide a substrate carrier and an arrangement for so as to overcome or at least alleviate the above mentioned prior art disadvantages. The objects of the invention are achieved by a substrate carrier which is characterized by what is stated in the characterizing portion of independent claim 1 . The objects of the present invention are further achieved by an arrangement which is characterized by what is stated in the characterizing portion of independent claim 7.

The preferred embodiments of the invention are disclosed in the dependent claims.

The invention is based on the idea of providing a substrate carrier for holding substrates during processing of the substrates by subjecting a surface of the substrate to successive surface reactions of at least a first precursor and a second precursor. The substrate carrier comprises two or more separate substrate holders which are stacked against each other. In one embodiment the substrate holders are arranged to receive one or two substantially planar substrates for processing the substrates in a reaction chamber of an atomic layer deposition apparatus. According to the present invention the two or more separate substrate holders are stacked against each other substantially in vertical direction and rigid end plates are arranged such that the stacked separate substrate holders are placed between the rigid end plates. Preferably at least one rigid end plate is arranged to provide a pressing force for pressing the stacked separate substrate holders against each other in vertical direction.

In the invention the stack of separate substrate holders is arranged between two rigid end plates and pressure is applied preferably by squeezing the rigid end plates and the stack of separate substrate holders together. This squeezing seals the substrate holders' edges such that the substrates are coated only on one side. In other words the interface between the substrate and the substrate holder is sealed such that the coating is not applied to the other side of the substrate. Rigid end plates ensure even pressure distribution along between substrate holders from the top of the stack to the bottom of the stack.

In an embodiment of the invention the separate substrate holders are plate-like elements or frame elements having a first side and a second side, and that the separate substrate holders are stacked against each other substantially in vertical direction such that the first side of one separate substrate holder is against the second side of a following separate substrate holder in vertical direction. The substrate carrier further comprises rigid end plates such that the stacked separate substrate holders are arranged between said rigid end plates and that a pressing force is applied to the stack of separate substrate holders through the rigid end plates such that the substrate holders are pressed against each other in vertical direction. Therefore the rigid end plate may comprise at least one compression device arranged to provide a pressing force for pressing the stacked separate substrate holders against each other in vertical direction.

The present invention is further based on the idea of providing an arrangement for supporting substantially planar substrates during processing of the substrates by subjecting a surface of the substrate to successive surface reactions of at least a first precursor and a second precursor. The arrangement comprises two or more substantially planar substrates having a first side surface and a second side surface, two or more separate substrate holders each of which is arranged to hold one or two substantially planar substrates during processing of the substrates. In the arrangement the separate substrate holders are stacked against each other for forming a stack such that flow channels are provided between following substrate holders in vertical direction for the least first precursor and second precursor. According to the present invention the two or more separate substrate holders are stacked against each other substantially in vertical direction. In one embodiment the separate substrate holders are plate-like elements and comprise a support surface for receiving the second side surface of a substantially planar substrate such that the flow channel is formed between the first side surface of the substantially planar substrate and the support surface of a following separate substrate holder in vertical direction, or that the separate substrate holder is a frame element and comprises a receptacle for receiving two superposed substantially planar substrates having second side surfaces placed against each other such that the flow channel is formed between the first side surface of the substantially planar substrate in one frame element and the first side surface of the substantially planar substrate in a following frame element in vertical direction. The arrangement may further comprise at least one compression device arranged to provide a pressing force for pressing the stacked separate substrate holders against each other in vertical direction.

One advantage of the substrate carrier and arrangement of the present invention is that by arranging rigid end plates on top and on bottom of the stacked separate substrate holders and arranging adjustable compression force to the stack of separate substrate holders through the rigid end plates enables pressing the separate substrate holders against each other such that the separate substrate holders are tightly against each other for providing adequate gas sealing between the separate substrate holders, but such that the compression force is not too high breaking the fragile substrates. The substrate holders may be further manufactured from thin material due to the adjustable compression force. The thin material provides a compact stack and saves space in the reaction chamber such that more substrate holders, and thus substrates, fit into the reaction chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

Figures 1A, 1 B, 1 C and 1 D show schematically separate substrate holders for holding substantially planar substrates;

Figure 2 shows schematically one embodiment of a substrate carrier according to the present invention; and

Figure 3 shows schematically another embodiment of a substrate carrier according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, for the purposes of clear explanation, a number of specific details are set forth in order to provide a thorough understanding of the invention. It is apparent to one skilled in the art that embodiments of the invention may, however, be practiced without one or more of these specific details or with some equivalent arrangement. Furthermore, the features of the specific embodiments described below may be combined in any suitable manner.

In the following examples substrates are shown as substantially planar, sheet-like or plate-like substrates. The substrates being substantially flat do not restrict the shape of the edge of the substrates and thus the substrates may have any suitable edge shape such as rectangle, octagon, circle or other. The present invention is not restricted to any particular substrate shape other than that the frame of the substrate must conform to the shape of the object to be coated. Furthermore the base material of the substrate may be Si, glass or any other material suitable to be processed with ALD. The first planar substrate 2 shown in figures 1A, 1 B and 1 C comprises a first side surface 6 and a second side surface 3. The second planar substrate 4 shown in figures 1A, 1 B and 1 C comprises a first side surface 8 and a second side surface 5.

Figures 1A, 1 B and 1 C show separate substrate holders 1 1 , 14, 60, 61 for holding one or two substantially planar or plate-like substrates 2, 4 during processing the substrates 2, 4 with atomic layer deposition (ALD) by subjecting the surface of the substrate 2, 4 to surface reactions of at least a first and second gaseous precursors according to the principles of (ALD).

Figure 1A shows one embodiment of a separate substrate holder 14 in which two planar substrates 2, 4 are arranged superposed on top of each other. The substrates 2, 4 are arranged such that the second side surface 3 of the first substrate 2 is against the second side surface 5 of the second substrate 4. In this arrangement it is desirable that only the first side surfaces 6, 8 of the first and second substrate 2, 4 are processed or coated during processing. In this embodiment the substrate holder 14 comprises a groove 16 which is formed with a first side wall 51 and a second side wall 52 of the substrate holder 14 for receiving side edges 10, 12 or edge region of the substrates 2, 4, the first and second side walls 51 , 52 forming the side walls of the groove 16. Accordingly the substrate holder forms a frame or cassette having the groove 16 for receiving the side edges 10, 12 of the superposed substrates 2, 4. It should be noted that although the embodiment of figure 1A shows two superposed substrates 2, 4 placed into the groove 16 formed by two side walls 51 , 52, this embodiment may also be used for only one substrate 2, 4 such that a side edge 10, 12 of the only one substrate 2, 4 is arranged into the groove 16.

In the substrate holder 14 of figure 1 A the side walls 51 , 52 may be formed and connected to each other for forming substantially U- or C-shaped groove 16. In the embodiment of figure 1A the groove 16 is formed as substantially U- or C-shaped groove, having a first side wall 51 , second side wall 52 and straight bottom wall 55 connecting the side walls 51 , 52. The first and second side wall 51 , 52 are arranged to extend over the first side surfaces 6, 8 and specifically edge regions of the first side surfaces 6, 8 of the substrates 2, 4. The side walls 51 , 52 extend substantially parallel with the first side surfaces 6, 8 of the substrates 2, 4 and over the first side surfaces 6, 8 such that the diffusion gap 56 is provided between the side walls 51 , 52 and the first side surfaces 6, 8 respectively. The side walls 51 , 52 may be arranged against the first side surfaces 6, 8 or there may be a small clearance. The side edges 10, 12 of the substrates 2, 4 may be arranged into the groove 16 such that the side edges 10, 12 are against or close to the bottom wall 55, thus forming a diffusion barrier. Therefore, a diffusion path is provided from the first side surface 6, 8 to the second side surface 3, 5 with the side walls 51 , 52 and bottom wall 55 of the substrate holder 14. The diffusion path comprises the diffusion gap 56 and the diffusion barrier. In an alternative embodiment the groove 16 of the substrate holder 14 may be formed as a U-shaped groove having curved or rounded bottom wall 55 (not shown). In a yet alternative embodiment the groove 16 of the substrate holder 14 may be formed as a C- shaped groove having curved or rounded side walls 51 , 52 and bottom wall 55 (not shown). The groove 16 may also be replaced with another kind receptacle capable of receiving two superposed substrates. The receptacle may be for example recess, cavity or retainer for receiving the side edges 10, 12 or edge regions of the two superposed substrates 2, 4. The embodiment of figure 1A the substrate holder 14 is formed for receiving two superposed substrate 2, 4 for enabling one sided processing or coating of the substrates 2, 4. So in figure 1A there are two substrates that are coated single-sided such that although two sides are coated only one side of each substrate is coated because the two substrates are in a back to back position in the substrate holder.

Figure 1 B shows an alternative embodiment of a separate substrate holder 1 1 arranged to receive only one substrate 2 having a first side surface 6 and a second side surface 3. The substrate holder 1 1 comprises a support surface 54 on which the substrate 2 is arranged such that the second side surface 3 of the substrate 2 is against the support surface 54. The support surface 54 preferably covers the whole second side surface 3. The substrate holder 1 1 further comprises a bottom wall 57 extending from the support surface 54 and a side wall 53 extending further from the bottom wall 57, as shown in figure 1 B. The bottom wall 57 may extend upwards, for example perpendicularly, from the support surface 54 and the side wall 53 may extend sideways, for example perpendicularly and/or parallel to the support surface 54, from the bottom wall 57 such that a recess 59, groove or some other kind of receptacle is formed for receiving the edge 10 or edge region of the substrate 2, as shown in figure 1 B. The side wall 53 extends a distance over the first side surface 6 such that a diffusion gap 58 is provided between the side walls 53 and the first side surface 6, respectively. The side wall 53 may be arranged against the first side surface 6 or there may be a small clearance. The side edges 10 of the substrate 2 may be arranged into the groove 59 such that the side edges 10, 12 are against or close to the bottom wall 57, thus forming a diffusion barrier. Therefore, a diffusion path is provided from the first side surface 6 to the second side surface 3 with the side wall 53 and bottom wall 57 of the substrate holder 1 1 . The diffusion path comprises the diffusion gap 58 and the diffusion barrier. In an alternative embodiment the groove 59 of the substrate holder 1 1 may be formed as a U-shaped groove having curved or rounded bottom wall 57 (not shown). In a yet alternative embodiment the groove 59 of the substrate holder 1 1 may be formed as a C-shaped groove having curved or rounded side walls 53 and bottom wall 57 (not shown). According to the above mentioned the separate substrate holder 1 1 is designed and constructed for enabling single sided processing, the first side surface 6, of the substrate 2 with atomic layer deposition.

Figure 1 C shows another embodiment of a separate substrate holder 23. In this embodiment the substrate holder 23 comprises a lower holder part 60 and an upper holder part 61 between which the substrates 2, 4 are arranged. The holder parts 60, 61 are arranged to receive edges of the substantially planar substrates 2, 4 between them, as shown figure 1 C. In this embodiment two planar substrates 2, 4 are positioned one on the other and supported between the holder parts 60, 61 and supported on support surfaces of the holder parts 60, 61 . Thus the processing of the second side surfaces 3, 5 of the substrates 2, 4 positioned against each other is substantially prevented and only the first side surfaces 6, 8 facing away from each other are processed enabling single sided processing. With the construction of the two- part substrate holder 23 the processing of the opposing side surfaces 3, 5 arranged against each other is effectively prevented. There is provided a diffusion gap 62 between the holder part 60, 61 and the first side surface 6, 8. The substrate holder 23 is preferably designed such that the first holder part 60 is positioned against the lower substrate 4 and the second holder part 61 against the upper substrate 4 when the substrates 2, 4 are installed to the substrate holder 23. The holder parts 60, 61 form together a groove 64, or recess or receptacle for receiving side edges of the substrates 2, 4. Thus the diffusion gap 62 maybe formed due to the surface roughness of the holder parts 60, 61 and the substrates 2, 4. The diffusion gap 62 effectively prevents starting materials from flowing between the superposed substrates 2, 4 and thus the material growth on the second side surfaces 3, 5. The holder parts 60, 61 may also comprise sealing surfaces, respectively, which are arranged against each other when the substrate holder 23 is assembled and the substrates 2, 4 are installed to the frame 23. A diffusion path 63 is further formed between the holder parts 60, 61 due to the surface roughness of the holder parts 61 , 60 and the sealing surfaces. The diffusion path 63 and the diffusion gap 62 provide a diffusion sealing preventing processing of the second side surfaces 3, 5. It should be noted that as the substrate holder 23 of figure 1 C comprises two holder parts 60, 61 and is arranged to receive two superposed substrates 2, 4, it may also comprise three or more holder parts and it may arranged to receive only one substrate 2, 4 or three or more substrates 2, 4. There may for example be separation part or spacer element between the supposed substrates 2, 4.

According to the above mentioned the separate substrate holder 14, 1 1 , 23 may be a plate-like, sheet-like element or a frame element having a first side and second side. In the embodiment of figure 1A the first side wall 51 forms the first side of the substrate holder 14 and the second side wall 52 forms the second side of the substrate holder 14. In the embodiment of figure 1 B the side wall 58 forms the first side of the substrate holder 1 1 and the support surface 54 forms the second side of the substrate holder 1 1 . In the embodiment of figure 1 C the separate substrate holder 23 consisting of two holder parts 60, 61 may be a plate-like, sheet-like element or a frame element having a first side and second side. The upper holder part 61 forms the first side of the substrate holder 23 and the lower holder part 62 forms the second side of the substrate holder 23. Accordingly, the substrate holder 1 1 , 14, 23 may be designed or constructed in any form such that it comprises a first side and a second side. The first and second side are preferably parallel to each other, and/or preferably parallel to the first and second side surfaces 6, 8, 3, 5 of the substrates 2, 4. However, the first and second side of the substrate holder 14, 1 1 , 23 may formed such that they do not extends parallel to each other and/or parallel to the first and second side surfaces 6, 8, 3 5, but in an angle.

In a preferred embodiment the substrate holder 14, 1 1 , 23 is formed as a perimeter, frame or ring such that all the side edges 10, 12 or the whole side edge 10, 12 of a substrate 2, 4 may be received into the groove 16, 59, 64. Thus the side walls 51 , 52, 53, 60, 61 may be arranged over the first side surfaces 6, 8 or edge regions thereof for forming the diffusion path. Figure 1 D show one embodiment in which the substrate holder or the side walls form a perimeter with the groove 16, 59, 64 for receiving all the side edges of a square shaped substrate 2, 4 such that the first side surface 6, 8 of the substrate is exposed for processing. In an alternative embodiment the substrate holder 14, 1 1 , 23 may comprise two opposing frame elements (not shown) which are arranged to receive opposite edges 10, 12 of the substrate 2, 4.

The substrates 2, 4 are supported during processing in a substrate carrier. The substrate carrier is arranged inside a reaction chamber of ALD apparatus, or alternatively the substrate carrier may form the reaction chamber when it is in operating state and the substrates are installed to it. The reaction chamber may further be arranged or installed inside a vacuum chamber of the ALD apparatus. In some embodiments the reaction chamber may also form the vacuum chamber. In the present invention is provided a substrate carrier for holding substrates 2, 4 during processing of the substrates 2, 4 by subjecting a surface 6, 8 of the substrate 2, 4 to successive surface reactions of at least a first precursor and a second precursor. The substrate carrier comprises two or more separate substrate holders 1 1 , 14, 23 which are stacked against each other.

Figure 2 shows an embodiment of a substrate carrier according to the present invention. As shown in figure 3 the substrate carrier comprises two or more two or more separate substrate holders 14 stacked against each other substantially in vertical direction. The substrate holders 14 may be any kind of separate substrate holders, such as shown in figures 1A, 1 B and 1 C, arranged to receive one or more substrates, preferably substantially planar substrates. The separate substrate holders 14 may be plate-like elements or frame elements having a first side and second side. The separate substrate holders 14 are stacked against each other substantially in vertical direction such that the first side of one separate substrate holder 14 is against the second side of a consecutive separate substrate holder 14 in vertical direction. As shown in figure 3 the separate substrate holders 14 are stacked against each other in vertical direction for forming a vertical stack 15. The vertical stack 15 may be provided to a support surface such that the separate substrate holders 14 are supported in vertical or substantially vertical direction, (not shown in figure).

The substrate carrier further comprises rigid end plates 70, 72 such that the stack 15 is arranged between said rigid end plates 70, 72. The rigid end plates 70, 72 are arranged against the vertically outermost of the stacked separate substrate holders 14. At least one rigid end plate 70, 72 is arranged to provide a pressing force for pressing the stack 15 and the stacked separate substrate holders 14 against each other in substantially vertical direction. Therefore at least one rigid end plate 70, 72 comprises at least one compression device arranged to provide a pressing force for pressing the stacked separate substrate holders 14 against each other in substantially vertical direction. The compression device compresses the separate substrate holders 14 against each other such that the gap 19 between successive separate substrate holders in minimized. Only one of the rigid end plates or both may comprise the compression device. The compression device may comprise a compression element 20, 26 for generating a pressing force. The compression element 20, 26 may comprise a spring, spring arrangement, hydraulic compression element, mechanical compression element, electrical compression element, or a thermal expansion compression element or some other kind of compression element capable for generating the substantially vertical pressing force F to the stack 15. The compression device may comprise one or more connection elements 22, 28 for connecting the compression element 20, 26 to the rigid end plate 70, 72. Thus the compression element 20, 26 may be operatively connected to the rigid end plate 70, 72 for directing the pressing force against the outermost of the stacked separate substrate holders 14 and/or the compression element 20, 26 is operatively connected to the rigid end plate 70, 72 for distributing the pressing force evenly against the outermost of the stacked separate substrate holders 14. The rigid end plate 70, 72 may be a rigid support plate or the like which enables distributing the pressing force F evenly against the outermost of the stacked substrate holders 14 and the substantially vertical stack 15. The compression element 20, 26 may be connected operatively to the rigid end plate 70, 72 with transmission mechanism 22, 28 for transmitting and distributing the pressing force F of the compression element 20, 26 to the rigid end plate 70, 72. The transmission mechanism may comprise for example transmission shaft 22, 28, transmission lever or any other kind of transmission means. The transmission mechanism 22, 28 transmits the pressing force F to the rigid end plate 70, 72 arranged against the outermost of the stacked separate substrate holders 14. The substrate carrier or the compression device may further comprise an adjustment device for adjusting the pressing force F of the compression device such that the stack 15 and the separate substrate holders 14 may be pressed against each other with predetermined or desired force F.

Figure 3 shows an alternative embodiment of the present invention in which the substrate carrier is comprises rigid end plates 70, 72 on both ends of the separate substrate holder stack 15 and both rigid end plates 70, 72 comprise a compression device 32, 40 arranged to provide a pressing force for pressing the stack 15 and the stacked separate substrate holders 14 against each other in substantially vertical direction. The compression device 32, 40 comprises a spring 38, 46 for generating pressing force F and transmission element 34, 42 for transmitting the pressing force to the rigid end plate 70, 72. The transmission element 34, 42 is a transmission lever 34, 42 pivoted with a hinge 36, 44 to the body of the compression device 32, 40. The spring 38, 46 is arranged to press against the transmission lever 34 for providing the pressing force F against the rigid end plate 70. 72. The compression device thus compresses the stack 15 such that the substrate holders 14 are pressed against each other such that the gaps 19 between the substrate holders 14 are minimized and the substrate holders 14 are arranged tightly against each other.

In another embodiment of the invention the substrate carrier may comprise more than one substantially vertical stack of separate substrate holders 14. This embodiment is not shown in figures but it is explained here shortly. The vertical stacks are separated from each other with partitioning elements or partitioning walls arranged between the successive stacks. The partitioning element may be rigid plate, or resilient wall element or any kind of element which may be arranged between successive stacks or dividing the successive separate substrate holders 14 to stacks 15. It should be noted that the substrate carrier according to the present invention may comprise two or more separate stacks arranged successive to each other and separated with the separation elements. The substrate carrier is further provided with rigid end plates arranged to the vertically outermost stacks and to the separate substrate holders 14 in substantially vertical direction. The rigid end plate is provided on both vertical ends of the successive stacks.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. A substrate carrier for holding substrates (2, 4) during processing of the substrates (2, 4) by subjecting a surface (6, 8) of the substrate (2, 4) to successive surface reactions of at least a first precursor and a second precursor, the substrate carrier comprising two or more separate substrate holders (11, 14, 23) which are stacked against each other, characterized in that the two or more separate substrate holders (11 , 14, 23) are stacked one on the other substantially in vertical direction, and that the substrate carrier further comprises rigid end plates (70, 72) such that the stacked separate substrate holders (11, 14, 23) are arranged between said rigid end plates (70, 72) and the rigid end plates (70, 72) are arranged to provide a pressing force for pressing the stacked separate substrate holders (11, 14, 23) against each other in vertical direction.

2. A substrate carrier according to claim 1, characterized in that at least one rigid end plate (70, 72) comprises a compression device (20,

22, 26, 28, 32, 34, 36, 38, 40, 42, 44, 46) and said at least one rigid end plate (70, 72) is arranged to provide a pressing force with the compression device (20, 22, 26, 28, 32, 34, 36, 38, 40, 42, 44, 46).

3. A substrate carrier according to claim 2, characterized in that the compression device (20, 22, 26, 28, 32, 34, 36, 38, 40, 42, 44, 46) comprises a compression element (20, 26, 38, 46) for generating a pressing force.

4. A substrate carrier according to claim 3, characterized in that the compression element (20, 26, 38, 46) comprises a spring, a hydraulic compression element, mechanical compression element, electrical compression element or a thermal expansion compression element for generating the pressing force.

5. A substrate carrier according to any preceding claims, characterized in that the separate substrate holders (11, 14, 23) are plate-like elements or frame elements having a first side (51 , 53) and a second side (52, 54) and that the separate substrate holders (11, 14, 23) are stacked against each other such that the first side (51 , 53) of one separate substrate holder (11, 14, 23) is against the second side (52, 54) of another separate substrate holder (11, 14, 23).

6. A substrate carrier according to claim 1 , c h a r a c t e r i z e d in that one rigid end plate (70, 72) is a support plate on which the stacked separate substrate holders (11, 14, 23) are arranged.

7. An arrangement for supporting substantially planar substrates (2, 4) during processing of the substrates (2, 4) by subjecting a surface (6, 8) of the substrate (2, 4) to successive surface reactions of at least a first precursor and a second precursor, the arrangement comprising:

- two or more substantially planar substrates (2, 4) having a first side surface (6, 8) and a second side surface (3, 5);

- two or more separate substrate holders (11, 14, 23) each of which is arranged to hold one or two substantially planar substrates (2, 4) during processing of the substrates (2, 4);

in which arrangement the separate substrate holders (11, 14, 23) are stacked against each other for forming a stack such that flow channels are provided between overlapping substrate holders (11, 14, 23) for the first precursor and the second precursor,

characterized in that the two or more separate substrate holders (11, 14, 23) are stacked one on the other substantially in vertical direction and that the arrangement further comprises rigid end plates (70, 72) which are arranged against the outermost of the stacked separate substrate holders (11, 14, 23), and the rigid end plates (70, 72) are arranged to provide a pressing force for pressing the stacked separate substrate holders (11, 14, 23) against each other in vertical direction.

8. An arrangement according to claim 7, characterized in that the separate substrate holder (11) is plate-like element and comprises a support surface (54) for receiving the second side surface (3, 5) of a substantially planar substrate (2, 4) such that the flow channel is formed between the first side surface (6, 8) of the substantially planar substrate (2, 4) and the support surface (54) of a following separate substrate holder (11, 14) in vertical direction, or that the separate substrate holder (14, 23) is a frame element (14, 23) and comprises a receptacle for receiving two superposed substantially planar substrates (2, 4) having second side surfaces (3, 5) placed against each other such that the flow channel is formed between the first side surface (6, 8) of the substantially planar substrate (2, 4) in one frame element (14, 23) and the first side surface (6, 8) of the substantially planar substrate (2, 4) in an following frame element (14, 23) in vertical direction.

9. An arrangement according to claim 8, characterized in that the rigid end plates (70, 72) on both ends of the stacked separate substrate holders (11, 14, 23) are arranged to provide a pressing force for pressing the stacked separate substrate holders (11, 14, 23) against each other in vertical direction.

10. An arrangement according to claim 8 or 9, characterized in that the rigid end plate (70, 72) comprises a compression device (20, 22, 26, 28, 32, 34, 36, 38, 40, 42, 44, 46) and said rigid end plate (70, 72) is arranged to provide a pressing force with the compression device (20, 22, 26, 28, 32, 34, 36, 38, 40, 42, 44, 46).

11. An arrangement according to claim 10, characterized in that the compression device (20, 22, 26, 28, 32, 34, 36, 38, 40, 42, 44, 46) comprises a compression element (20, 26, 38, 46) for generating a pressing force, or that the compression device (20, 22, 26, 28, 32, 34, 36, 38, 40, 42, 44, 46) comprises a spring (38, 46), hydraulic compression element (20, 26), mechanical compression element, electrical compression element, or a thermal expansion compression element for generating the pressing force.

12. An arrangement according to claim 11, characterized in that the compression device (20, 22, 26, 28, 32, 34, 36, 38, 40, 42, 44, 46) is operatively connected to the rigid end plate (70, 72) for directing the pressing force against the outermost of the stacked separate substrate holders (11, 14, 23), or that the compression device (20, 22, 26, 28, 32, 34, 36, 38, 40, 42, 44, 46) is operatively connected to the rigid end plate (70, 72) for distributing the pressing force evenly against the outermost of the stacked separate substrate holders (11, 14, 23).