WO2016135377A1

WO2016135377A1 - Apparatus for subjecting a surface of a substrate to successive surface reactions

Info

Publication number: WO2016135377A1
Application number: PCT/FI2016/050095
Authority: WO
Inventors: Pekka Soininen
Original assignee: Beneq Oy
Priority date: 2015-02-25
Filing date: 2016-02-16
Publication date: 2016-09-01
Also published as: CN107429396B; CN107429396A

Abstract

The invention relates to an apparatus for subjecting a surface of a substrate to successive surface reactions. The apparatus comprises a gas manifold comprising (2) at least one precursor feeding channel (4) and at least one discharge channel. Part of the gas manifold forms a fixed part (2a). There is at least one removable part between the fixed part (2a) of the gas manifold (2) and the substrate holder (6). The gas manifold (2) further comprises a gas distributor (8) for supplying precursor to the surface of the substrate (1) and for discharging precursor from the surface of the substrate. The gas distributor (8) is arranged as a removable part.

Description

APPARATUS FOR SUBJECTING A SURFACE OF A SUBSTRATE TO SUCCESSIVE SURFACE REACTIONS

FIELD OF THE INVENTION

The present invention relates to an apparatus according to the preamble of claim 1 and more particularly to an apparatus for subjecting a surface of a substrate to successive surface reactions of at least a first precursor and a second precursor. The apparatus further comprises a gas manifold comprising at least one precursor feeding channel for supplying precursor to the surface of the substrate and at least one discharge channel for discharging precursor from the surface of the substrate. Part of the gas manifold forms a fixed part. The apparatus further comprises a substrate holder for holding said substrate, and the substrate holder is movable in a vertical direction for moving the substrate between a process position and a loading position. BACKGROUND OF THE INVENTION

Atomic layer deposition (ALD) is conventionally carried out in a reaction chamber under vacuum conditions. One or more substrates are first loaded into the reaction chamber and then vacuum is evacuated into the reaction chamber and the reaction space inside the reaction chamber is heated to process temperature. The atomic layer deposition is then carried out by supplying at least first and second gaseous precursors into the reaction chamber alternatingly and repeatedly for providing a coating layer with desired thickness on the surface of the substrate. A full ALD cycle, in which the first and second precursor are supplied into the reaction chamber comprises: supplying a pulse of first precursor into the reaction chamber, purging the first precursor from the reaction chamber, supplying a pulse of second precursor into the reaction chamber and purging the second precursor from the reaction chamber. Purging precursors may comprise discharging the precursor material from the reaction chamber, supplying purge gas, such as nitrogen, into the reaction chamber and discharging the purge gas. When desired number of ALD cycles and thus a desired coating layer thickness is reached, the vacuum in the reaction chamber is vented and the substrates are unloaded from the reaction chamber. Then the same process is repeated for the next substrates.

During ALD process the surface of a substrate is coated with the precursors but at the same time other surfaces of the reaction chamber are coated as well. So the coating deposition is formed aii over the reaction chamber, in order to maintain good quality the surfaces have to be cleaned at intervals. When an ALD apparatus is part of a cluster tool cleaning of the apparatus becomes a very important issue because it affects to other cluster members as well. Normally the reaction chamber is opened and the surfaces can then be cleaned or parts can be taken away and cleaned outside the reaction chamber but at. the same time the vacuum is vented and it has to be evacuated before a next ALD cycle can be processed. Evacuating vacuum and venting it as well heating the reaction space takes significant amount of time. Evacuating vacuum into the reaction chamber is slow as aii the moisture, e.g. in form of water, has to be boiled out of the reaction chamber in the low pressure conditions. Clearly, this slows down the overall coating process.

Often it is not desirable to coat all the surface of the substrate and thus different kinds of masks have to be used on the surface of the substrates in order to prevent coating from growing on certain parts of the substrates. Masking is very difficult as the precursor gases tend to diffuse between the mask and the surface of the substrate and thus quality is compromised. A mask can be used for more than one substrate so it can be seen as part of the apparatus while the substrate is a piece that is only part of an arrangement in the apparatus during the processing of the substrate.

Overall, venting the vacuum is one of the biggest disadvantages when the surfaces of the reaction chamber have to be cleaned or when a mask has to be cleaned or replaced with a new one and this is very challenging in a cluster tool when it affects to the whole cluster.

BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is to alleviate the above disadvantages. The objects of the invention are achieved by an apparatus which is characterized by what is stated in the independent claim. The preferred embodiments of the invention are disclosed in the dependent claims.

The invention is based on the realization that the apparatus for coating a substrate with an ALD process needs maintenance regularly and the maintenance time is too long especially when the apparatus is part of a cluster because the vacuum has to be vented and evacuated again before the process can be continued and this takes a lot of time so in order to reduce the time loss it is desirable to maintain the vacuum while parts of the apparatus can still be cleaned regularly.

The present invention is based on an apparatus for subjecting a surface of a substrate to successive surface reactions of at least a first precursor and a second precursor, the apparatus comprising a gas manifold for supplying precursor materials to the surface of the substrate. The gas manifold comprises at least one precursor feeding channel for supplying precursor to the surface of the substrate and at least one discharge channel for discharging precursor from the surface of the substrate. The apparatus further comprises a substrate holder for holding said substrate; the substrate holder is movable in a vertical direction for moving the substrate between a process position and a loading position. The gas manifold comprises a fixed part and between said fixed part and the substrate holder at least one removable part. In other words part of the gas manifold forms a fixed part and at least one separate removable part is arranged between the fixed part of the gas manifold and the substrate holder. In the invention, the gas manifold further comprises a gas distributor comprising a supply passage for supplying precursor from the precursor feeding channel to the surface of the substrate and a discharge passage for discharging precursor from the surface of the substrate to the discharge nozzle. The gas distributor is arranged as a removable part, or at least one of the removable parts.

In an embodiment of the invention the fixed part comprises a fixed cover plate, at least one precursor feeding channel and the at least one discharge channel.

The gas manifold and a bottom part form a reaction chamber having a reaction space in which the substrate is processed. Walls of the gas manifold defining the reaction space form an output face through which precursors are supplied into and discharged from the reaction space. The bottom part can be formed for example by the substrate and/or a frame structure holding a mask and/or any other suitable part closing the reaction space. Therefore the reaction space is formed between the output face and the bottom part. Precursors are supplied from the precursor feeding channel through the output face to the reaction space and toward the substrate and discharged from the reaction space through the output face to the discharge channel. The output face of the gas manifold defines the reaction chamber together with the bottom part. The apparatus further comprises at least one lifter for moving the removable part of the gas manifold in a vertical direction. In other words the lifter is movable in the vertical direction. In one embodiment of the invention the lifter is the substrate holder, which means that the substrate holder and the lifter for moving the removable part of the gas manifold in a vertical direction is the same part. In another embodiment of the invention the lifter is a separate part from the substrate holder.

The apparatus further comprises a mask for defining a coating area on the substrate, said mask forming at least part of the separate removable part. In an embodiment of the invention the gas manifold preferably comprises a mask for defining one or more coating areas on the substrate, said mask forming at least part of the removable part of the gas manifold. Said mask can be moved in a vertical direction with the lifter the lifter being either the same as the substrate holder or a separate lifter. When the substrate holder moves both the substrate and the mask the apparatus may comprise a supporting structure which separates the mask from the substrate after they have first moved together a distance such that the mask and the substrate can be removed from the apparatus separately.

In one embodiment of the invention the apparatus is provided with lifter for the substrate for loading or removal of the substrate and same type of lifter for the mask or other removable part of the apparatus. With the lifter the mask can be pressed against the bottom part of the reaction chamber during the ALD process and when it is time for changing or cleaning the mask it is vertically moved with the lifter and removed from the apparatus the same way as the substrate is removed after coating.

The lifter may be a plurality of positioning pins or some other movable means that can hold the removable parts of the apparatus. Each removable part of the apparatus may have its own lifter or they may have a lifter in common.

The removable part in the context of this application means that the part is removable without disassembling the apparatus. The part is removable during normal operation condition of the apparatus e.g. for a cleaning purpose or for other maintenance of the part. The removable part is removed from the apparatus without disassembling the apparatus. The removable part is different than a detachable part which is removed by using tools when disassembling the apparatus. A substrate is not part of the apparatus and is not considered as a removable part. The removable part is preferably removable during the loading position of the apparatus and not in the process position of the apparatus.

An advantage of the apparatus of the invention is that the vacuum conditions of the apparatus can still be maintained while the parts of the apparatus that need to be cleaned can be taken outside the apparatus for cleaning.

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 attached drawings, in which

Figure 1 shows one embodiment of the apparatus according to the invention;

Figure 2 shows another embodiment of the apparatus according to the invention;

Figure 3 shows yet another embodiment of the apparatus according to the invention;

Figure 4 shows yet another embodiment of the apparatus according to the invention; and

Figure 5 shows yet another embodiment of the apparatus according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows an apparatus according to the invention which comprises a gas manifold 2 for supplying precursor materials to a surface of a substrate 1. The gas manifold 2 comprises an output face 3, at least one precursor feeding channel 4 for supplying precursor to the surface of the substrate 1 and at least one discharge channel 5 for discharging precursor from the surface of the substrate 1. The precursor is supplied and discharged through the output face 3. The apparatus further comprises a substrate holder 6 for moving said substrate 1 in a vertical direction. The substrate holder 6 is movable in a vertical direction for moving the substrate 1 between a process position and a loading position. The process position is the position in which the substrate 1 is during coating of the substrate, i.e. when the precursor is supplied on the surface of the substrate 1. This means that during the process position the surface of the substrate 1 is in fluid connection with the output face 3 of the gas manifold 2 such that the surface of the substrate 1 is subjected to surface reactions of a first and a second precursor. This means that the substrate 1 is moved toward the output face 3 of the gas manifold 2 such that a reaction chamber 9 is formed between the output face 3 and the substrate 1 so that precursors are supplied to the surface of the substrate 1 and react on the surface of the substrate 1. The loading position is the position in which the substrate 1 is loaded to the apparatus such that it is arranged on the substrate holder 6. In other words, the substrate holder 6 is moved away from the process position in which the substrate 1 arranged on the substrate holder 6 is in fluid connection with the output face 3 of the gas manifold 2 to the loading position such that there is enough space for unloading a coated substrate 1 and loading an uncoated substrate 1 to the substrate holder 6 to be coated in the process position. Loading and unloading of the substrates to and from the substrate holder can be done with any suitable device, e.g. robotically with an industrial robot or other robotic device. After the uncoated substrate 1 is loaded to the substrate holder 6 the substrate holder 6 is moved in a vertical direction toward the output face 3 of the gas manifold 2 such that the substrate 1 is arranged in operational connection with the output face 3 of the gas manifold 2. The substrate holder 6 comprises a retainer 6a for holding the substrate 1 on the substrate holder 6. The retainer 6a may be a pin head of the vertically movable substrate holder 6 or a p!ate like structure that is supported by the vertically movable substrate holder 6. The retainer 6a, which can be a plate like structure, can extend the whole width of the substrate 1 or just part of the width. In figure 1 the retainer 6a extends only a part of the width of the substrate 1 and in figure 2 the retainer 6a extends the whole width of the substrate 1 and in figures 3 and 4 the retainer 6a is the head of the pin. The gas manifold 2 further comprises a fixed part 2a and between said fixed part 2a and the substrate holder 6 at least one removable part.

in figure 1 a mask 7 is arranged between the output face 3 of the gas manifold 2 and the substrate holder 6. The mask 7 is arranged between the output face 3 of the gas manifold 2 and the substrate 1 for covering the surface of the substrate 1 to prevent parts of the surface from being subjected to precursors. The mask 7 comprises openings 17 for providing precursor access to the surface of the substrate 1. So the precursors are supplied to the surface of the substrate 1 through the openings 17 of the mask 7 and subject the areas of the surface of the substrate 1 under the openings 17 to the 7

surface reactions of at least the first and second precursors. Using a mask 7 only part of the surface of the substrate is processed. The mask 7 may be manufactured from any suitable material, such as a thin metal plate comprising for example metal, like invar steel, glass or plastic or any combination thereof. The mask 7 may also be a uniform element without openings for covering part of the surface of the substrate 1 in which coating is not supplied so that the coating is only supplied onto the areas not covered by the mask 7. In the embodiment shown in figure 1 the mask 7 is arranged as a removable part and is vertically movable such that it can be taken away from the apparatus and cleaned or replaced with a new mask in the loading position with any suitable loading device, e.g. with an industrial robot or other robotic device. In other words the mask 7 vertically movable from the process position in which the mask 7 is on the surface of the substrate 1 and near the output face 3 of the gas manifold 2 to the loading position in which the mask is removable so that it can be taken from the apparatus and put back again or replaced with a new one. In this embodiment the mask 7 is movable with a first lifter 21 as is shown in figure 1. So the apparatus further comprises a first lifter 21 for moving the at least one separate removable part in a vertical direction, in another embodiment of the invention the mask 7 and the substrate 1 are arranged to be movable with a common lifter which is the substrate holder 6 holding the substrate 1. The gas manifold 2 can be made of one or more than one material, for example from different metals.

According to the invention, figure 1 shows an apparatus in which the gas manifold 2 comprises a gas distributor 8 having the output face 3 through which the precursors are supplied toward the surface of the substrate 1. The gas distributor 8 comprises a supply passage 4a for supplying precursor from the precursor feeding channel 4 to the surface of the substrate 1 and a discharge passage 5a for discharging precursor from the surface of the substrate 1 to the discharge nozzle 5. The gas distributor 8 can be arranged as a removable part that can be removed for maintenance in a loading position. At least part of the gas distributor 8 may be also a part of the fixed part 2a of the gas manifold. The gas distributor 8 can be arranged to be vertically movable together with the mask 7 so that they are movable with the first lifter 21 of the mask 7. In figure 1 , the mask 7 and the gas distributor 8 are moved together with the first lifter 21 when the gas distributor 8 is removable. In the process position the mask 7 is pressed against the substrate 1 and edges of the mask 8

7 are preferably pressed against the gas distributor 8 which is further pressed toward the fixed part 2a of the gas manifoid 2. The gas distributor 8 can comprise several materials. The gas distributor 8 can be made of plates forming a plate structure or from a metal piece in which the channels are formed by machining or from any other suitable material or structure. In an embodiment of the invention the first lifter 21 is arranged to move the mask 7.

Figure 2 shows another embodiment of the apparatus according to the invention in which the gas distributor 8 is formed as a sandwich structure from two gas distributors, a first gas distributor 8a and a second gas distributor 8b. The gas manifold 2 comprises a precursor feeding channel 4 for supplying precursor to the surface of the substrate 1 and at least one discharge channel 5 for discharging precursor from the surface of the substrate 1. The precursor feeding channel 4 and the discharge channel 5 extend through the first gas distributor 8a and the second gas distributor 8b as a supply passage and as a discharge passage such that the first gas distributor 8a comprises a first part of the supply passage 4aa and the second gas distributor 8b comprises a second part of the supply passage 4ab for supplying precursor from the precursor feeding channel 4 to the surface of the substrate 1 and further the first gas distributor 8a comprises a first part of the discharge passage 5aa and the second gas distributor 8b comprises a second part of the discharge passage 5ab for discharging precursor from the surface of the substrate 1 to the discharge nozzle 5. In other words the gas distributor 8 comprises at least a first gas distributor 8a and a second gas distributor 8b connected to each other and forming a supply passage 4a for supplying precursor from the precursor feeding channel 4 to the surface of the substrate 1 and a discharge passage 5a for discharging precursor from the surface of the substrate 1 to the discharge nozzle 5.

The second gas distributor 8b comprises the output face 3 which is toward the substrate to be coated and when there is a mask 7 also toward the mask 7. A reaction chamber 9 is formed between the output face 3 of the gas manifold 2 and the substrate 1 held by the substrate holder 6. The second gas distributor 8b forms the side wails of the reaction chamber 9 according to the embodiment shown in figure 2 whereas the gas distributor 8 forms the side walls of the reaction chamber 9 shown in figure 1. The sandwich structure of the gas distributor 8 is formed preferably such that the first gas distributor 8a stacked on the second gas distributor 8b having the output face 3 has a longer channel for the discharge of the precursor than the second gas distributor 8b, i.e. the gas distributor having the output face 3. The longer discharge channel in the first gas distributor 8a is for depleting the unreacted precursors that are discharged from the surface of the substrate 1. In this embodiment only the second gas distributor 8b is arranged as a removable part because the second gas distributor 8b having the output face 3 is the only part of the gas distributor 8 that gets contaminated by residue built up by unreacted precursors over time. In this embodiment the second gas distributor 8b is arranged as a removable part and moved with the second lifter 22 for moving the second gas distributor 8b in the vertical direction, the mask 7 is arranged as a removable part and moved with the first lifter 21 and substrate 1 is moved with the substrate holder 6. So in one embodiment of the invention the apparatus further comprises a second lifter 22 for moving the gas distributor 8 in a vertical direction. In another embodiment of the invention the apparatus further comprises a second lifter 22 for moving at feast the second gas distributor 8b in a vertical direction.

In another embodiment of the invention the first gas distributor 8a is also arranged as a removable part to be removable together with the second gas distributor 8b with the second lifter 22. So the first gas distributor 8a and the second gas distributor 8b are both arranged as a removable part.

In still another embodiment of the invention the second gas distributor 8b and the mask 7 are arranged as a removable part and are moved together with a common lifter.

In still another embodiment of the invention the first gas distributor 8a, the second gas distributor 8b and the mask 7 are ai! arranged as one removable part and are moved together with a common lifter. The first gas distributor 8a and the second gas distributor 8b can be removable together such that they are connected together for forming a separate removable part or they can be removable such that the first gas distributor 8a is a separate removable part and the second gas distributor 8b is another separate removable part.

Figure 3 shows a third embodiment of the apparatus according to the invention in which the substrate 1 and the mask 7 are movable together in the vertical direction. The apparatus further comprises a supporting structure 20 for supporting the removable part of the gas manifold 2 when the removable part reaches the position in which it can be removed from the apparatus. In other words, the removable part together with the substrate 1 are movable in the vertical direction such that the removable part is movable in said direction until it arrives at a level in which the supporting structure 20 contacts the removable part such that said removable part ends the movement and the substrate 1 continues the movement downward in the vertical direction. The removable part in figure 3 is the mask 7 (substrates are objects that are treated with the apparatus but they are not parts of the apparatus). In this embodiment only one lifter is needed for moving the substrate 1 and the mask 7 in a vertical direction, the lifter being the substrate holder 6. When the substrate holder 6 moves from the process position toward the loading position, i.e. downward away from the gas manifold 2, the substrate holder 6 holds both the substrate 1 and the mask 7 and moves them together downward in the vertical direction until the mask 7 reaches the supporting structure 20 and is supported by the supporting structure 20 to stay there while the substrate 1 continues the movement together with the substrate holder 6. When the already coated substrate is removed from the substrate holder 6 and an uncoated substrate 1 is loaded to the substrate holder 6 it moves vertically upward toward the gas manifold 2. During the movement upward the substrate holder 6 reaches the level of the supporting structure 20 and the substrate 1 makes a contact with the mask 7 such that the substrate 1 and the mask 7 are moved together toward the gas manifold 2.

In figure 4 another embodiment of the invention is shown in which the gas distributor 8 is a removable part which is moved with a second lifter 22 for moving said gas distributor 8 in vertical direction and the mask 7 is moved with the first lifter 21 In other words the figure 4 shows an embodiment comprises three different lifters, the first being the substrate holder 6, the second being the first lifter 21 and the third being the second lifter 22.

Still an embodiment is shown in figure 5 in which the apparatus comprises a susceptor 19. Activation by one or more precursors with plasma can also be used. Plasma is advantageously generated into the reaction chamber 9 between the output face 3 and the susceptor 19 by means of electrodes placed on the output face 3 and the susceptor's 19 surface (electrodes not shown). In the process position, the substrate 1 is advantageously supported with a susceptor 19 that can be positioned in vertical direction with a susceptor lifter 23. The susceptor 19 preferably operates as a pedestal for the substrate 1 so that it brings the substrate 1 and possible other parts such as the mask to the process position and also preferably thermally stabilizes them.

In an embodiment where the gas distributor 8 is also removable or the gas distributor 8 comprises a part that is removable the gas distributor 8, or its removable part, can also be moved together with the mask 7 and the substrate 1 the same way as described above.

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. An apparatus for subjecting a surface of a substrate (1) to successive surface reactions of at least a first precursor and a second precursor, the apparatus further comprising a gas manifold (2) comprising at least one precursor feeding channel (4) for supplying precursor to the surface of the substrate (1) and at least one discharge channel (5) for discharging precursor from the surface of the substrate (1), part of the gas manifold (2) forming a fixed part (2a);

a substrate holder (6) for holding said substrate (1), the substrate holder (6) is movable in a vertical direction for moving the substrate (1) between a process position and a loading position; characterized in that the apparatus further comprises:

at least one removable part between the fixed part (2a) of the gas manifold (2) and the substrate holder (6),

the gas manifold (2) further comprising a gas distributor (8) comprising a supply passage (4a) for supplying precursor from the precursor feeding channel (4) to the surface of the substrate (1) and a discharge passage (5a) for discharging precursor from the surface of the substrate (1) to the discharge nozzle (5), the gas distributor (8) being arranged as a removable part.

2. An apparatus according to claim 1, characterized in that the apparatus further comprises a mask (7) for defining a coating area on the substrate (1), said mask (7) forming at least part of the removable part.

3. An apparatus according to claim 1 or 2, characterized in that the gas distributor (8) comprises at least a first gas distributor (8a) and a second gas distributor (8b) connected to each other and forming a supply passage (4a) for supplying precursor from the precursor feeding channel (4) to the surface of the substrate (1) and a discharge passage (5a) for discharging precursor from the surface of the substrate (1) to the discharge nozzle (5).

4. An apparatus according to claim 3, characterized in that the second gas distributor (8b) is arranged as a removable part.

5. An apparatus according to claim 3, characterized in that the first gas distributor (8a) and the second gas distributor (8b) are both arranged as a removable part.

6. An apparatus according to any of claims 2 - 5, characterized in that the substrate holder (6) is arranged to move the mask (7) in vertical direction.

7. An apparatus according to any previous claim, characterized in that the apparatus further comprises a first lifter (21) for moving the at least one separate removable part in a vertical direction.

8. An apparatus according to claim 7, characterized in that the first lifter (21) is arranged to move the mask (7).

9. An apparatus according to any of claims 2 - 8, characterized in that the apparatus further comprises a second lifter (22) for moving the gas distributor (8) in a vertical direction.

10. An apparatus according to any of claims 2 - 8, characterized in that the apparatus further comprises a second lifter (22) for moving at least the second gas distributor (8b) in a vertical direction.

11. An apparatus according to any previous claim, characterized in that the fixed part (2a) comprises a fixed cover plate, at least one precursor feeding channel (4) and the at least one discharge channel (5).