WO2014191622A1

WO2014191622A1 - Barrier, carrier arrangement and method for preventing material growth

Info

Publication number: WO2014191622A1
Application number: PCT/FI2014/050419
Authority: WO
Inventors: Jarmo Maula; Janne Peltoniemi; Shuo Li
Original assignee: Beneq Oy
Current assignee: Beneq Oy
Priority date: 2013-05-29
Filing date: 2014-05-27
Publication date: 2014-12-04
Anticipated expiration: 2015-11-29

Abstract

The invention relates to a mask, carrier arrangement, method and use for preventing material growth on a portion of a surface (4, 6, 10, 12) of a substrate (2, 8) during processing of the substrate (2, 8) by subjecting the surface (4,6, 10, 12) of the substrate (2, 8) to successive surface reactions of at least a first precursor and a second precursor. The mask being arranged to be placed on the substrate (2, 8) such that it covers the portion of the surface (4, 6, 10, 12) of the substrate (2, 8). In the present invention the mask comprises a porous element (20, 24, 29, 32, 42, 44, 54) arranged to be provided against at least part of the portion of the surface (4, 6, 10, 12) of the substrate (2, 8).

Description

Barrier, carrier arrangement and method for preventing material growth

FIELD OF THE INVENTION

The present invention relates to a barrier for preventing material growth on a surface of a substrate, and especially to a barrier for preventing material growth on a portion of a surface of a substrate during processing of the substrate by subjecting the surface of the substrate to successive surface reactions of at least a first precursor and a second precursor, the barrier being arranged to be placed on the surface of the substrate such that it covers the portion of the surface of the substrate, the barrier comprising an absorption element arranged to be placed against the portion of the surface of the substrate and to absorb precursors entering between the surface of the substrate as defined in the preamble of independent claim 1 . The present invention also relates to a carrier arrangement for one or more substrates, and more specifically to a carrier arrangement for supporting one or more substrates during processing the substrates by subjecting a surface of the substrate to successive surface reactions of at least a first precursor and a second precursor, the carrier arrangement comprising: one or more substrates to be processed, a support surface to which the one or more substrates are supported during processing, and at least one absorption element arranged against at least part of the portion of the surface for preventing material growth on the portion of the surface the substrate during processing of the substrate, as defined in the preamble of independent claim 8. The present invention further relates to a method for processing a surface of a substrate by subjecting the surface of the substrate to successive surface reactions of at least a first precursor and a second precursor, the method comprising supporting one or more substrates having a first substantially planar surface on a support surface, as defined in the preamble of independent claim 22.

BACKGROUND OF THE INVENTION

Atomic layer deposition (ALD) is generally known coating method in which surfaces of a substrate are subjected to alternating surface reactions of at least a first and second gaseous precursors. 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 the 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 many planar or plate like substrates only from one of the main surfaces or sides or a certain portion of a surface of a substrate is preferably left without coating. However, due to the excellent conformality of the ALD-method, the coating tends to grow on all the surface of the substrate and thus also on the portions of the surfaces where it is undesirable.

In prior art the undesirable coating on a portion of a surface of a substrate is solved etching or otherwise removing the coating from the portion of the substrate surface in which it is undesirable after processing the substrate. However, etching or other removing of coating from the substrate add cost, it can be difficult or impossible 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 preventing coating formation on a predetermined portion of the surfaces of a substrate. The coating formation is prevented by placing a mask on the portion of the surface of the substrate on which no coating formation is wanted. The mask may be a separate solid mask element or alternatively the substrate is arranged against a support surface or some other solid surface for preventing coating formation on the surface or a portion of the surface of the substrate which is placed against the support surface. 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 mask 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 in the real production environment. This problem arises from the fact that often there is a small gap between the surface of the substrate and the mask or the support surface. The gap is usually formed due surface roughness, small particles, thermal expansion movements or other dimensional variations in the substrates or support surfaces. The precursor molecules may diffuse to the gap between the surface of the substrate and the mask or between the surface of the substrate and the support surface or the surface of another substrate. When precursor molecules diffuse to the gap they also form a coating on the surfaces defining the gap. The molecules diffuse to a certain diffusion distance into the gap from the edge of the gap forming coating layers on the surface of the substrate on which the coating is undesirable. Therefore, the prior art solutions do not efficiently prevent coating formation on the portion of the surface of the substrate. BRIEF DESCRIPTION OF THE INVENTION

The object of the present invention is to provide a barrier, barrier arrangement and method so as to overcome or at least alleviate the prior art disadvantages. The objects of the present invention are achieved with a barrier according to the characterizing portion of claim 1 . The objects of the present invention are further achieved with a carrier arrangement according to the characterizing portion of claim 8. The objects of the present invention are also achieved with a method according to the characterizing portion of claim 22.

The preferred embodiments of the invention are disclosed in the dependent claims. The present invention is based on the idea of providing a barrier comprising a base-element and an absorption element or absorption material layer which is placed against at least a portion of a surface of the substrate on which the material growth is desired to be prevented during processing of the substrate by subjecting the surface of the substrate to successive surface reactions of at least a first precursor and a second precursors. The base-element has lower specific surface area and/or lower porosity than the absorption element The absorption element comprises pores, openings, cavities, recesses, holes or the like which provide an increased specific surface area. The absorption element may be formed from porous or fibrous material or from a net, a mesh, a wire cloth, woven cloth, non-woven cloth or a plate or an element provided with openings, recesses, holes or the like which provide increased surface area for material growth. ALD material growth in the absorption element is mainly diffusion type growth as precursor molecules diffuse into the absorption element. In the present invention the term absorption element relates generally to material or an element having high porosity and/or high specific surface area, especially in relation to the porosity and/or specific surface area of the substrate.

According to the above mentioned the barrier is used in the present invention for preventing material growth on a portion of a surface of a substrate during processing of the substrate by subjecting the surface of the substrate to successive surface reactions of at least a first precursor and a second precursor. The barrier is arranged to be placed on the substrate such that it covers the portion of the surface of the substrate. This means that the barrier is placed on the portion of the substrate such that the absorption element is against the portion of the surface of the substrate for preventing or minimizing material growth or surface reactions on the portion of the surface. The barrier is preferably removable such that it may be removed after the processing without deteriorating the substrate.

The absorption element may also be used in a carrier arrangement for supporting one or more substrates during processing the substrates by subjecting the surface of the substrate to successive surface reactions of at least a first precursor and a second precursor. The carrier arrangement comprises one or more substrates, at least one support surface or substrate support for supporting the substrate and at least one absorption element arranged between the substrate and the support surface for preventing material growth on the surface of the substrate between the support surface and the substrate such that the absorption element covers at least a portion of the surface of the substrate between the support surface and the substrate for preventing material growth on the portion of the surface of the substrate during the processing of the substrate.

The present invention also provides a method for processing a surface of a substrate by subjecting the surface of the substrate to successive surface reactions of at least a first precursor and a second precursor, the method comprising supporting one or more substrates having a first substantially planar surface on a support surface and arranging at least one absorption element between the first substantially planar surface of the substrate and the support surface for preventing material growth between the support surface and the first substantially planar surface of the substrate. The advantage of the barrier, carrier arrangement and method according to the present invention is that it prevents or essentially decreases the diffusion material growth on the substrate surface in a gap between the surface of the substrate and a barrier or a support surface. When the absorption element is used, the gap is formed between the absorption element and the surface of the substrate. The higher porosity or specific surface of the absorption element absorbs the precursor molecules diffused in to the gap and/or provides an increased opportunities and high surface area for the diffused precursor molecules to react. Thus the diffused molecules can react with the absorption element and inside the pores or opening or the like of the absorption element or material. Therefore, the distance the molecules can diffuse into the gap decreases significantly. As the surface of the absorption element or material comprises pores or openings the precursor molecules may enter the pores or openings and thus the molecules are absorbed inside the absorption element or material such that the precursor molecules may also react on the inner surfaces of the pores or openings. Accordingly the precursor molecules diffused into the gap have higher possibility to react on the surfaces of the absorption element or material than on the surface of the substrate in the gap. Therefore, the material growth on the portion of the surface of the substrate which is covered with the barrier or support surface is prevented or at least essentially decreased.

BRIEF DESCRIPTION OF THE DRAWINGS

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 A and 1 B show schematically prior art arrangements for processing substrates by atomic layer deposition;

Figures 2A and 2B show schematically one embodiment for preventing material growth on a portion of a substrate;

Figures 3A and 3B show schematically another embodiment for preventing material growth on a portion of a substrate; Figure 4A and 4B show schematically embodiments for processing a substrate placed on a substrate support according to the present invention; Figure 5 shows schematically one embodiment of the present invention in which two substantially planar substrates are placed against each other;

Figure 6 shows schematically another embodiment in which two substantially planar surfaces are placed against each other; and Figure 7 shows schematically an embodiment in which two against each other placed substrates are arranged on a substrate carrier.

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 under- standing 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. Figures 1A and 1 B schematically show prior art arrangement for holding substrates during processing the substrates by subjecting the surface of the substrate to successive surface reactions of at least first and second precursors according to the principles of atomic layer deposition (ALD). In the following examples substrates are shown as substantially planar, sheet-like or plate-like substrates. However the substrates may have any shape and the present invention is not restricted to any substrate shape. Furthermore the base material of the substrate may be Si, glass or any other material suitable to be processed with ALD.

Figure 1A shows a planar substrate 2 having a first surface 6 and second surface 4 on opposite sides of the substrate 2. The substrate 2 is supported on a substrate support 20 having a support surface 22. The substrate 2 is arranged on the substrate support 20 such that the first side 6 of the substrate is placed against the support surface 22. In this kind of arrangement the support surface 22 covers the first surface of the substrate 6 and material growth on the first lower surface 6 of the substrate 2 is undesirable. Therefore, in this kind of arrangement the object is to provide coating only on the second upper surface 4 of the substrate 2. Thus the substrate support 20 forms a barrier for preventing material growth on the first surface 6 of the substrate 2. However, even if the first surface 6 of the substrate 2 and the support surface 22 are substantially planar and straight there remains a tiny gap 14 between the support surface 22 and the first surface 6 of the substrate 2. In figure 1 A the gap 14 is exaggerated for illustrative purposes. Usually the gap 14 is larger than the diameter of precursor molecules and thus the precursor molecules 14 may diffuse a certain diffusion distance into the gap 14 from the edge 3 of the substrate 2. Thus a unwanted diffusion material growth is also formed on the first surface 6 of the substrate 2 along the mentioned diffusion distance.

Figure 1 B shows another substrate carrier arrangement in which two substrates 2 and 8 are placed or supported against each other. The first substrate 2 comprises a first surface 6 and a second surface 4 on opposite sides of the first substrate 2. The second substrate 8 comprises a first surface 12 and a second surface 10 on opposite sides of the second substrate 8. The substrates 2, 8 are arranged against each other such that the first surface 6 of the first substrate 2 is against the first surface 12 of the second substrate 8. In this kind of arrangement the first surfaces 6, 12 of the first and second substrate 2, 8 cover each other and material growth on the first surfaces 6, 12 of the substrates 2, 8 is undesirable. Therefore, in this kind of arrangement the object is to provide coating only on the second surfaces 4, 10 of the substrates 2, 8. Thus the substrates 2, 8 may form barriers to each other for preventing material growth on the first surfaces 6, 12. However, when even if the first surfaces 6, 12 of the substrates 2, 8 are substantially planar and straight there remains a tiny gap 16 between the first surfaces 6, 12. In figure 1 B the gap 16 is exaggerated for illustrative purposes. Usually the gap 16 is larger than the diameter of precursor molecules and thus the precursor molecules 16 may diffuse a certain diffusion distance into the gap 16 from the edges 3, 5 of the substrates 2, 8. Thus a diffusion material growth is also formed on the first surfaces 6, 12 of the substrates 2, 8 along the mentioned diffusion distance. In the above prior art embodiments the first or second surface 6, 4, 12, 10 of the substrates 2, 8 may also be only partly covered by the support surface 22 or another substrate 2, 8. Furthermore, the special barrier may be placed on a portion of the first or second surfaces 6, 4, 12, 10 of the substrates for preventing material growth on the mentioned portion. In this kind of arrangement the gap is formed between the substrate surface 6, 4 12, 10 and the barrier covering only the portion of the surface.

Figures 2A and 2B show one embodiment of the present invention in which a barrier 28 is placed on the second surface 4 of the substrate 2. In this embodiment the barrier 28 covers a portion, half, of the second surface 4 of the substrate 2 for preventing material growth on the mentioned portion of the second surface 4, as shown in figure 2B. The barrier 28 comprises a base- element or base layer 31 and an absorption element or layer 29. The absorption element 29 is placed against the portion of the second surface 4 of the substrate 2.

In the context of this description, as whole, the barrier means any member which may be placed on the surface of the substrate or on which the substrate may be placed. Furthermore, the absorption element means any element, layer or material capable of absorbing gaseous precursor materials. The absorption element is thus provided with high or relatively high specific surface area. More particularly the absorption element is thus provided with increased specific surface area in relation to the substrate material such that the precursor molecules diffused between the surface of the substrate and the barrier will be diffused and absorbed into the absorption element. Thus the specific surface area of the absorption element is higher than the specific surface area of the substrate material, and preferably also higher than the material of the support surface on which the substrate is supported. The high specific surface area of the absorption element is provided such that the absorption element comprises pores, openings, cavities, recesses, holes or the like for providing the increased specific surface area. Therefore, the absorption element may be formed from porous or fibrous material for providing a porous absorption element. Alternatively or the absorption element may be formed as a net, a mesh, a wire cloth, woven cloth, non-woven cloth or a plate or an element provided with openings, recesses, holes or the like for providing a screen-like or labyrinth-like absorption element.

In one embodiment an absorption element may be structure with etched holes used with a substrate during processing. In this embodiment film grows inside the absorption element. Surface area may decrease towards the end of the lifetime of the absorption element as precursors react on the surface of the absorption element and holes close up. Area ratio of the absorption element is TT*D*H/(D+S)², in which S = spacing between holes, D=diameter of the hole H=Depth of the hole. Thus when the diameter of the holes is 50μηη, spacing between holes 10μηη and depth is 1 mm, the surface ratio is 22. When the hole diameter is 5μηη then the surface ratio is of course 2.2. If the process is carried out such that it makes 30 nm film on the substrate, then it takes (50-5)/0.03/2= 750 ALD cycles to drop the ratio by one decade.

A porous absorption element, porous material or porous layer or the like means in this context that the porous absorption element has higher porosity and/or specific surface area than the substrate. In one embodiment the porosity of the porous absorption element may be at least 10 times greater than the porosity of the substrate, preferably or alternatively the porosity of the porous absorption element may be at least 25 times greater than the porosity of the substrate. In one embodiment the specific surface area of the porous absorption element may be at least 10 times greater than the specific surface area of the substrate, preferably or alternatively the specific surface area of the porous absorption element may be at least 20 times greater than the specific surface area of the substrate, more preferably or alternatively the specific surface area of the porous absorption element may be at least 50 times greater than the specific surface area of the substrate. In one embodiment the porous absorption element may comprise pores having average diameter of at least 5 to 100 times the provided or planned coating thickness of the substrate, or preferably average diameter of at least 50 to 100 times the coating provided or planned thickness of the substrate. It should be noted that the above mentioned numerical values may change from one embodiment to another depending on the characteristics of the substrate and the porous absorption element. Porosity, or void fraction, is a measure of the void or empty spaces in a material, and is a fraction of the volume of voids over the total volume. Porosity may be calculated or measured in many known manners. On the other hand, specific surface area is a material property of solids which measures the total surface area per unit of mass, solid or bulk volume, or cross-sectional area. In one embodiment of the present invention the porous absorption element may be formed from paper or paper-based material, from porous ceramic material, metal material, polymeric material, composite material or some other material having the necessary porosity and/or specific surface area. The porous absorption element may be a substantially planar porous material layer, and/or a flexible porous material layer or a rigid porous material layer.

A screen-like or labyrinth-like absorption element, material or layer or the like means in this context that the absorption element comprises opening, holes, cavities, recesses or the like providing has higher specific surface area than the substrate. In one embodiment the specific surface area of the screen- or labyrinth- like absorption element may be at least 10 times greater than the specific surface area of the substrate, preferably or alternatively the specific surface area of the absorption element may be at least 20 times greater than the specific surface area of the substrate, more preferably or alternatively the specific surface area of the absorption element may be at least 50 times greater than the specific surface area of the substrate. In one embodiment the screen- or labyrinth-like absorption element may comprise holes, openings or cavities having average diameter of at least 5 to 100 times the provided or planned coating thickness of the substrate, or preferably average diameter of at least 50 to 100 times the coating provided or planned thickness of the substrate. It should be noted that the above mentioned numerical values may change from one embodiment to another depending on the characteristics of the substrate and the porous absorption element. The specific surface area is a material property of solids which measures the total surface area per unit of mass, solid or bulk volume, or cross-sectional area. In one embodiment of the present invention the screen- or labyrinth-like absorption element may be formed from metal, steel, aluminum, polymeric material, ceramic material, metal material or fibrous material and formed as a net, a mesh, a wire cloth, woven cloth, non-woven cloth or a plate or an element provided with openings, recesses, holes or the like for providing a screen-like or labyrinth-like absorption element. The screen- or labyrinth-like absorption element may therefore be for example a woven element or solid element provided with holes, openings, cavities, recesses or the like. The openings or the like may be provided by machining the absorption element, such as drilling or laser. The screen- or labyrinth-like absorption element absorption element may be a substantially planar material layer, and/or a flexible material layer or a rigid material layer. In one embodiment the absorption element is a wire cloth made of steel wires having wire diameter of 30 μιτι and distance between wires 50 μιτι. Each deposition reduces the available free volume of the mesh due to coating. The distance between the surfaces to be coated is limited by the construction of the mesh. For example, each deposition run, carried out by repeated ADL cycles, deposits 100 nm film. Mesh-like structure is used and the open space for the coating is essentially rectangular, between the wires of the mesh. The free space is reduced effectively by 200 nm of film in each deposition run, because film grows conformally on all sides. If the aperture size (distance between wires in the mesh) is 10 m then the volume is fully filled after about 10 μιτι / 200 nm = 50 process runs. In theory the surface area of the wires in mesh, using single layer of round wires related to flat area (the area what mesh covers) is equal to 2^*TT*D/(D+A), in which A = distance between wires, D=diameter of the wire . Maximum is thus =2 ^*π ~=6.18. If A=D then area relation = π. Thick wires give more surface area, but reduce flexibility. It is also possible to add several mesh-like structures on top of each other to increase the total surface area.

In one embodiment wire cloth / mesh as absorption element is arranged between the substrate and support surface. In this case film grows on the outer surface of the absorption element. Surface area increases towards the end of the lifetime. The area of wire (round) surface related to flat area (the area what mesh covers) is equal to actually TT*D/(D+A), in which A= distance between wires, D=diameter of the wire. The absorption element may also be soft or it may compress when placed against the surface of the substrate. Thus the absorption element may conform to the surface of the substrate decreasing the gap and therefore also the diffusion of precursor molecules. As, shown in figure 2A, the barrier 28 may comprise a base-element 31 and the absorption element 29. The absorption element 29 may be fixedly or removably connected or attached to the base element 31 , or by fixed or removable manner. The base-element 31 preferably has lower porosity or lower specific surface area than the absorption element 29. The base-element 31 may provide rigidness to the mask and also prevent absorption of precursor materials straight from the gas atmosphere, from upper side of mask 28 in figure 2A, to the absorption element 29. The base-element 31 further provides a counter surface and thus the absorption element 29 is arranged between the base-element 31 and the surface 4 of the substrate 2. Figures 2A and 2B show an embodiment in which base-element 31 is a substantially planar element, and the at least one absorption element 29 is provided on one side of the base-element 31 . It should be also noted that the form and shape of the base-element 31 and the absorption element 29 may vary in different applications. In one embodiment the barrier 28 may be provided with at least two absorption elements 29 one on each side, opposite sides, of the substantially planar base-element 31 . The barrier 28 of figures 2A and 2B is provided as a multilayered barrier 28 having a base layer 31 and an absorption layer 29 on one side of the base layer 31 . In an alternative multilayered barrier 28 at least one absorption layer 29 may be provided on both sides of the base layer 31 such that one substrate 2 may be placed against both surfaces of the barrier 28, or the barrier 28 may be placed between two substrates 2. The base element 31 may also be at least part of substrate carrier or substrate support arranged to support one or more substrates during the processing, such as the surface support 20 of figures 1A and 1 B. The barrier 28 may further comprise attachment means for attaching the barrier 28 on the surface 4 of the substrate 2. In one embodiment the barrier 28 comprises at least one adhesive layer or adhesive element 33 for attaching the barrier on the surface 4 of the substrate 2. Preferably the adhesive layer or adhesive element 33 is arranged to removably attach the barrier 28 on the substrate 2. In figures 2A and 2B the absorption element 29 covers the entire base element 31 . However, as the diffusion growth happens only along a certain diffusion distance from the edge of the barrier 28 towards the center of the barrier 28 in the gap between the absorption element 29 and the surface 4 of the substrate 2, the porous element 29 may be provided only the edge region the portion covered by the mask 28. This kind of embodiment is shown in figure 3A, in which the barrier element 28 comprises a base layer 31 and a frame-like absorption element 29 provided only to the edge region of the base layer 31 . The frame-like absorption element 39 means absorption element 29 covers only the edge regions of the surface 4 of the substrate 2 leaving the central area of the substrate without absorption element, as shown with the dotted line in figure 3A.

Figure 4A shows schematically an embodiment of a carrier arrangement for substrates 2 for processing the substrates 2 by subjecting the surface 4 of the substrate 2 to successive surface reactions of at least a first precursor and a second precursor. The carrier arrangement comprises a substrate support 20 having a support surface 22 for supporting the substrate 2. The arrangement further comprises an absorption element placed to cover a portion of the surface 6 of the substrate 2 for preventing material growth on the portion of the surface of the substrate during the processing of the substrate 2. This arrangement corresponds the arrangement shown in figure 1A. As the substrate 2 is place on the substrate support 20 such that the support surface 22 and the first surface 6 of the substrate 2 are against each other, the substrate support 20 forms the absorption element in this embodiment. To achieve this, the substrate 2 and the substrate support 20 have to have at least one substantially conforming surfaces. In the shown embodiment the substrate 2 comprises at least a first substantially planar surface 6 to be placed against the support surface 22. Thus the substrate 2 is arranged on the substrate support 20 such that the substrate support 20 supports the substrate 2 from the first substantially planar surface 6 for providing the absorption element on the first substantially planar surface 6. For preventing material growth in the gap 14 between the support surface 22 and the first surface 6 of the substrate 2, an absorption element is provided against the first surface 6 of the substrate 2 according to the present invention. In the embodiment of figure 4A the substrate support 20 is arranged to form the absorption element for preventing material growth on the first surface 6 of the substrate 2. Furthermore, the substrate support 20 is formed itself as an absorption element and the gap 14 is formed between the substrate support 20, the absorption element, and the substrate 2. Thus the substrate support 20 forms the the absorption element. This means that the substrate support 20 is arranged against the first surface 6 of the substrate 2 such that it prevents direct exposure of the first surface 6 to the precursors.

Figure 4B shows on another embodiment of the present invention in which a absorption element 24 or absorption layer is provided between the substrate support 20 or support surface 22 and the first substantially planar surface 6 of the substrate 2. Thus the gap, diffusion gap, is formed between the absorption layer 24 and the first surface 6 of the substrate 2. The absorption element 24 may further be provided with a base-element or base layer 27, such that the absorption element 24 and the base-element 27 together form the barrier. It should be noted that the base-element 27 may also be omitted, such that the barrier is formed only with the absorption element 24 or with the absorption element 24 and the substrate support 20. The absorption element 24 is arranged against the first surface 6 such that the surface 26 of the absorption element 24 is against the first surface 6. The base layer 27 is arranged against the support surface 22. The absorption element 24 or the barrier may be separate element or film or layer or multilayered element provided between the first substantially planar surface 6 of the substrate 2 and the substrate support 20. Alternatively the absorption element 24 or the barrier may be provided to the substrate support 20 as an integral element or as a removable element, as shown in figure 4B. In one embodiment the absorption element 24 is separate element arranged on the support surface 22. The base layer or base-element 27 preferably has lower porosity than the absorption element 24 and/or lower specific surface area than the absorption element 24. In one embodiment the substrate support 20 forms the base element, or the substrate support 20 forms both the barrier and the base element.

Figure 5 shows an alternative embodiment the carrier arrangement of the present invention in which two substrates 2 and 8 are arranged against each other. This arrangement substantially corresponds the arrangement of figure 1 B. This carrier arrangement comprises a first substrate 2 comprising a first substantially planar surface 6 and a second surface 4, and a second substrate 8 comprising a first substantially planar surface 12 and a second surface 10, the first substantially planar surface 6 of the first substrate 2 and the first substantially planar surface 12 of the second being arranged against each other such that the first substrate 2 may form the barrier for the second substrate 8 and the second substrate 8 may form the barrier element for the first substrate 2. Thus the superposed substrates 2, 8 prevent material growth on the first surfaces 6, 12 of the substrates 2, 8. According to the present invention an absorption element 32 is arranged between the first substantially planar surface 6 and the second substantially planar surface 12. Accordingly the first surface 34 of the absorption element 32 is provided against the first surface 6 of the first substrate 2 and the second surface 36 of the absorption element 32 is provided against the first surface 12 of the second substrate 8. The absorption element 32 may be attached to the first surfaces 6, 12 of the substrates 2, 8, preferably by removable manner, or it may be a separate or loose element. The attaching of the absorption element 32 may be carried out by adhesive material. In this embodiment the absorption element 32 forms the barrier alone or the barrier is formed with the absorption element 32 and one of the substrates 2, 8. Figure 6 shows another embodiment in which a multilayered barrier 40 is provided between two substrates 2, 8 in the same manner as in figure 5. In this embodiment the barrier 40 comprises a base-element or a base layer 41 and absorption layers or elements 42 and 44 on each side of the substantially planar base-element 41 . The base-element 41 may have lower porosity than the absorption elements 42, 44 on both sides of the base-element 41 and/or the base- element 41 may have lower specific surface area than the absorption elements 42, 44 on both sides of the base-element 41 . The base-element 41 may for example be Si-based material or glass. The absorption elements 42, 44 may be removably or fixedly attached to the base layer 41 . Figure 7 shows an embodiment in which two superposed or against each other placed substrates 2, 8 are arranged on a substrate support 50. The substrate support 50 comprises one or more substrate holders 52 for receiving the first and second substrate 2, 8 provided with the absorption element 54 between the first and second substrate 2, 8. The first and second substrate 2, 8 are arranged against each other with the absorption element 54 between in the same manner as shows and described in connection with figures 5 and 6. The substrates holders 52 may be any kind of holders arranged to receive the substrates 2, 8 to the substrates support 50. The absorption element 54 may correspond to the absorption elements described above and it may be attached to the substrates 2, 8 or it may be a separate element placed between the substrates 2, 8. In one embodiment the absorption element 54 may be an integral part of the substrate support 50 or it may be attached to the substrate support 50 or it may be totally separate part. Thus in one embodiment the absorption element 54 is provided to the substrate support 50, and that the one or more substrate holders 52 are arranged to receive one first and one second substrates 2, 8 on opposite sides of the absorption element 54 such that the first substantially planar surface 6 of the first substrate 2 and the second substantially planar surface 12 of the second substrate 8 are against the absorption element 54. In this embodiment the absorption element 54 forms the barrier alone or the barrier is formed with the absorption element 54 and one of the substrates 2, 8. In an alternative embodiment the barrier is formed as a multilayered part comprising a base- element and an absorption element 54 on one or both sides of the base-element.

The present invention further relates to a method for processing a surface 4, 6 of a substrate 2, 8 by subjecting the surface 4, 6 of the substrate 2, 8 to successive surface reactions of at least a first precursor and a second precursor. The method of the present invention further comprises covering a portion of the surface 6, 12 of the substrate 2, 8 with an absorption element by placing the absorption element against the portion of the surface 6, 12 of the substrate 2, 8 before processing the substrate. The covering may be carried out by spreading absorption material or porous material on the portion of the surface of the substrate 2, 8 or by placing or attaching a barrier comprising an absorption element or layer on the surface of the substrate. Alternative the absorption element or material may be placed between a substrate support and the substrate, or between two substrates 2, 8 having at least one substantially planar surface such that the absorption element is against a first substantially planar surface 6 of a first substrate 2 and a first substantially planar surface 12 of a second substrate 8.The absorption element may be placed detachably, or detachable manner, against the portion of the surface 6, 12 of the substrate 2, 8.

According to the above described the present invention provides use of a porous material for preventing material growth on a portion of a surface of a substrate arranged during processing the substrate by atomic layer deposition. The present invention also provides use of a porous material for preventing diffusion material growth between a surface of a substrate and a substrate support during processing the substrate by atomic layer deposition. Furthermore, the present invention provides use of porous material between two against each other arranged substrates for preventing diffusion material growth between the two substrates during processing the substrate by atomic layer deposition. Accordingly, in all the embodiment of the present invention the porous element or layer forms an absorption member for absorbing molecules diffused into the gap. The porous element may also be considered as a diffusion barriers preventing or at least reducing diffusion of the molecules into the gap between substrates or substrate and substrate support or a mask or other kind of barrier element. The present invention also relates to use of a barrier for preventing material growth on a portion of a surface of a substrate during processing the substrate by atomic layer deposition, use of an absorption element for preventing diffusion material growth between a surface of a substrate and a support surface during processing the substrate by atomic layer deposition and use of an absorption element between two against each other arranged substrates for preventing diffusion material growth between the two substrates during processing the substrates by atomic layer deposition.

It is apparent to a person skilled in the art that as technology advanced, the basic idea of the invention can be implemented in various ways. The invention and its embodiments are therefore not restricted to the above examples, but they may vary within the scope of the claims.

Claims

1 . A barrier for preventing material growth on a portion of a surface (4, 6, 10, 12) of a substrate (2, 8) during processing of the substrate (2, 8) by subjecting the surface (4, 6, 10, 12) of the substrate (2, 8) to successive surface reactions of at least a first precursor and a second precursor, the barrier being arranged to be placed on the surface (4, 6, 10, 12) of the substrate (2, 8) such that it covers the portion of the surface (4, 6, 10, 12) of the substrate (2, 8), the barrier comprising an absorption element (20, 24, 29, 32, 42, 44, 54) arranged to be placed against the portion of the surface (4, 6, 10, 12) of the substrate (2, 8) and to absorb precursors entering between the surface (4, 6, 10, 12) of the substrate (2, 8)

characterized in that the barrier comprises a base-element (20, 27, 31 , 41 ) having lower specific surface area and/or lower porosity than the absorption element (24, 29, 42, 44).

2. A barrier according to claim 1 , characterized in that the absorption element (20, 24, 29, 32, 42, 44, 54) comprises pores, openings, cavities, recesses, holes or the like for providing increased specific surface area.

3. A barrier according to claim 1 or 2, characterized in that the absorption element (20, 24, 29, 32, 42, 44, 54) is formed from:

- porous or fibrous material for providing a porous absorption element;

- a net, a mesh, a wire cloth, woven cloth, non-woven cloth or a plate or an element provided with openings, recesses, holes or the like for providing a screen- like absorption element;

- paper or paper-based material, ceramic material, porous metal material or polymeric material; or

- that the absorption element (20, 24, 29, 32, 42, 44, 54) is a screen-like absorption element formed from metal, steel, aluminum, polymeric material, ceramic material or fibrous material.

4. A barrier according to any one of claims 1 to 3, characterized in that the absorption element (20, 24, 29, 32, 42, 44, 54) is:

- a substantially planar material layer; or

- a flexible material layer; or

- a rigid material layer.

5. A barrier according to claim 1 , characterized in that the base-element (20, 27, 31 , 41 ) is a substantially planar element, and the at least one absorption element (24, 29, 42, 44) is provided on one or both sides of the base-element (20, 27, 31 , 41 ); or that the base-element (20, 27, 31 , 41 ) is a base-element layer (31 , 41 ), and the at least one absorption element (24, 29, 42, 44) is provided as an absorption layer on one or both sides of the base-element (20, 27, 31 , 41 ).

6. A barrier according to claim 1 or 5, characterized in that base-element (20) is at least part of a substrate support arranged to support one or more substrates (2, 8) during the processing, or that the base-element is a substrate (2, 8) such that the absorption element (24, 29, 42, 44) is arranged between substrates.

7. A barrier according to any one of claims 1 to 6, characterized in that:

- the barrier further comprises attachment means for attaching the barrier (28, 32, 40) on the surface of the substrate (2, 8); or

- the barrier (20, 28, 32, 40, 54) further comprises at least one adhesive layer or adhesive element (33) for attaching the barrier on the surface (4, 6, 10, 12) of the substrate (2, 8).

8. A carrier arrangement for supporting one or more substrates (2, 8) during processing the substrates (2, 8) by subjecting a surface (4, 6, 10, 12) of the substrate (2, 8) to successive surface reactions of at least a first precursor and a second precursor, the carrier arrangement comprising:

- one or more substrates (2, 8) to be processed;

- a support surface (22) to which the one or more substrates (2, 8) are supported during processing; and

- at least one absorption element (20, 24, 29, 32, 42, 44, 54) arranged against at least part of the portion of the surface (4, 6, 10, 12) for preventing material growth on the portion of the surface (6, 12) the substrate (2, 8) during processing of the substrate (2, 8),

characterized in that the at least one absorption element (20, 24, 29, 32, 42, 44, 54) is arranged between the substrate (2, 8) and the support surface (22) for preventing material growth on the surface (4, 6, 10, 12) of the substrate (2, 8) between the support surface (22) and the substrate (2, 8).

9. A carrier arrangement according to claim 8, characterized in that the absorption element (20, 24, 29, 32, 42, 44, 54) comprises pores, openings, cavities, recesses, holes or the like for providing increased specific surface area.

10. A carrier arrangement according to claim 8 or 9, characterized in that the absorption element (20, 24, 29, 32, 42, 44, 54) is formed from:

- porous or fibrous material for providing a porous absorption element; or

- a net, a mesh, a wire cloth, woven cloth, non-woven cloth or a plate or an element provided with openings, recesses, holes or the like for providing a screenlike absorption element;

- paper or paper-based material, ceramic material, metal material or polymeric material; or

- that the absorption element (20, 24, 29, 32, 42, 44, 54)is a screen-like absorption element formed from metal, steel, aluminum, polymeric material, ceramic material or fibrous material.

1 1 . A carrier arrangement according to claim any one of claims 8 to 10, characterized in that

- the porosity of the absorption element (20, 24, 29, 32, 42, 44, 54) is at least 10 times greater than the porosity of the substrate (2, 8); or

- the porosity of the absorption element (20, 24, 29, 32, 42, 44, 54) is at least 25 times greater than the porosity of the substrate (2, 8).

12. A carrier arrangement according to any one of claims 8 to 1 1 , characterized in that:

- the specific surface area of the absorption element (20, 24, 29, 32, 42, 44, 54) is at least 10 times greater than the specific surface area of the substrate (2, 8); or

- the specific surface area of the absorption element (20, 24, 29, 32, 42, 44,

54) is at least 20 times greater than the specific surface area of the substrate (2, 8); or

- the specific surface area of the absorption element (20, 24, 29, 32, 42, 44, 54) is at least 50 times greater than the specific surface area of the substrate (2, 8).

13. A carrier arrangement according to any one of claims 8 to 12, characterized in that absorption element (20, 24, 29, 32, 42, 44, 54) is a porous element having pores with:

- an average diameter of at least 5 to 100 times the coating thickness of the substrate (2, 8); or

- an average diameter of at least 50 to 100 times the coating thickness of the substrate (2, 8); orthat absorption element (20, 24, 29, 32, 42, 44, 54) is a screenlike element having opening, holes or the like with:

- an average diameter of at least 50 to 100 times the coating thickness of the substrate (2, 8).

14. A carrier arrangement according to any one of claims 8 to 13, characterized in that the absorption element (20, 24, 29, 32, 42, 44, 54) is:

- a substantially planar material layer; or

- a flexible material layer; or

- a rigid material layer.

15. A carrier arrangement according to any one of claims 8 to 14, characterized in that the support surface (22) has lower porosity than the absorption element (24, 29, 42, 44) and/or lower specific surface area than the absorption element (24, 29, 42, 44).

16. A carrier arrangement according to any one of claims 8 to 15, characterized in that the support surface (22) is provided by a substantially planar element (20, 27, 31 , 41 ), and the at least one absorption element (24, 29, 42, 44) is provided on one or both sides of the substantially planar element (20, 27, 31 , 41 ).

17. A carrier arrangement according to any one of claims 8 to 16, characterized in that the carrier arrangement comprises substrate support (20) or a substrate holder, and the substrate support (20) or the substrate holder comprises the support surface (22).

18. A carrier arrangement according to the claim 17, characterized in that the substrate (2, 8) is arranged on the substrate support (20) or the substrate holder such that the support surface (22) supports the substrate (2, 8) from a first substantially planar surface (6, 12) and the at least one absorption element (20, 24, 29, 32, 42, 44, 54) is arranged between the support surface (22) and the first substantially planar surface (6, 12) of the substrate (2, 8).

19. A carrier arrangement according to claim 17 or 18, characterized in that the absorption element (24) is a separate layer or an element provided between the first substantially planar surface (6, 12) of the substrate (2, 8) and the support surface (22) of the substrate support (20) or substrate holder, or that the absorption element (24) is provided to the substrate support (20) or substrate holder as an integral element or as a removable element.

20. A carrier arrangement according to any one of claims 8 to 16, characterized in that the carrier arrangement comprises a first substrate (2) comprising a first substantially planar surface (6) and a second substrate (8) comprising a first substantially planar surface (12), the first substantially planar surface (6) of the first substrate (2) and the first substantially planar surface (12) of the second substrate (8) being arranged against each other and the absorption element (20, 24, 29, 32, 42, 44, 54) is arranged between the first substantially planar surface (6) of the first substrate (2) and the first substantially planar surface (12) of the second substrate (8), and that the first substantially planar surface (6) of the first substrate (2) forms the support surface for the second substrate (8) and the first substantially planar surface (12) of the second substrate (8) forms the support surface for the first substrate (2).

21 . A carrier arrangement according to the claim 20, characterized in that the one or more substrate holders (52) is arranged to receive the first and second substrate (2, 8), and the absorption element is provided between the first and second substrate (2, 8).

22. A method for processing a surface (4, 10) of a substrate (2, 8) by subjecting the surface (4, 6, 10, 12) of the substrate (2, 8) to successive surface reactions of at least a first precursor and a second precursor, the method comprising:

- supporting one or more substrates (2, 8) having a first substantially planar surface (6, 12) on a support surface (22), characterized in that the method further comprises arranging at least one absorption element (20, 24, 29, 32, 42, 44, 54) between the first substantially planar surface (6, 12) of the substrate (2, 8) and the support surface (22) for preventing material growth between the support surface (22) and the first substantially planar surface (6, 12) of the substrate (2, 8).

23. A method according to claim 22, characterized by:

- placing the absorption element (20, 24, 29, 32, 42, 44, 54) between a substrate support (20) and the first substantially planar surface (6, 12) of substrate (2, 8), the substrate support (20) comprising the support surface (22); or

- placing the absorption element (20, 24, 29, 32, 42, 44, 54) between a support surface of a substrate holder and the first substantially planar surface (6, 12) of the substrate (2, 8), the substrate support (20) comprising the support surface (22); or

- placing the absorption element (20, 24, 29, 32, 42, 44, 54) between two substrates (2, 8) (6, 12) such that the absorption element (20, 24, 29, 32, 42, 44, 54) is against a first substantially planar surface (6) of a first substrate (2) and a first substantially planar surface (12) of a second substrate (8), the first substantially planar surface (6) of the first substrate (2) forming the support surface for the second substrate (8) and the the first substantially planar surface (12) of a second substrate (8) forming the support surface for the first substrate (2).

24. Use of a barrier according to any one of claims 1 to 7 for preventing material growth on a portion of a surface (6, 12) of a substrate (2, 8) during processing the substrate (2, 8) by atomic layer deposition.

25. Use of an absorption element according to any one of claims 1 to 7 for preventing diffusion material growth between a surface (6, 12) of a substrate (2, 8) and a support surface (22) during processing the substrate (2, 8) by atomic layer deposition.

26. Use of an absorption element according to any one of claims 1 to 7 between two against each other arranged substrates (2, 8) for preventing diffusion material growth between the two substrates (2, 8) during processing the substrates (2, 8) by atomic layer deposition.