Effusion device for localised deposition for use in a vacuum chamber

Abstract

The object of the invention is an effusion device for localised deposition for use in a vacuum chamber. The effusion device comprises an end piece (4) having a chamber (5) for a material to be deposited, wherein the effusion device further comprises a laser light source (1) for heating the material to be deposited, at least one optical fibre (2) for guiding the laser light from the laser light source (1) to the end piece (4), and a fibre coupling system (3) for coupling the laser light from the laser light source (1) to the at least one optical fibre (2).

Description

[0001] Effusion device for localised deposition for use in a vacuum chamber

[0002] Field of the Invention

[0003] The present invention relates to an effusion device for localized deposition for use in a vacuum chamber, which operates on the principle of an effusion cell and which uses laser light to heat the material to be deposited.

[0004] Background of the Invention

[0005] Currently, there are devices that use effusion flow, a phenomenon in which particles of deposited material move from a higher temperature location to a lower temperature location, to deposit materials on a substrate. These devices, called effusion cells, are designed for installation in vacuum chambers and comprise a cup for storing the material to be deposited. The material in the cup is heated, which leads to its evaporation or sublimation and the released vapour atoms of this material fall on the surface of the substrate, where they gradually form a layer. This process takes place in a vacuum, which affects not only the paths of the atoms but also the resulting purity of the layer.

[0006] The heating of the material to be deposited is in the case of effusion cells usually provided by either a resistive electrical body or by the impact of accelerated electrons. However, resistance heating is not suitable for materials with high melting temperature and heating by electrons can only be used under higher vacuum conditions.

[0007] Another disadvantage lies in the larger dimensions of the effusion cells, which are in the order of units to tens of centimetres. The effusion cell is also mounted rigidly in the vacuum chamber and aimed at one specific location, wherein the minimum diameter of the deposited area is typically in the order of units to tens of millimetres. This prevents a well-localized deposition. In addition, the dimensions of the effusion cell are also increased by water cooling, which is required when depositing materials with high evaporation or sublimation temperatures.

[0008] A high vacuum (in the order of 10’3Pa to 10’8Pa) is also required to operate a conventional effusion cell, where the mean free path of atoms and molecules is comparable to the distance of the cell from the substrate (typically about 10 cm).

[0009] It would therefore be desirable to come up with a solution for an effusion device which, compared to conventional effusion cells, would have a smaller dimensions to allow a well-localised deposition and which would not require cooling or a higher vacuum level.

[0010] Summary of the Invention

[0011] The above-mentioned drawbacks are to some extent eliminated by an effusion device for localized deposition for use in a vacuum chamber, the essence of which lies in the fact that it comprises an end piece having a chamber for a material to be deposited, wherein the effusion device further comprises a laser light source for heating the material to be deposited, at least one optical fibre for guiding the laser light from the laser light source to the end piece, and a fibre coupling system for introducing the laser light from the laser light source into the at least one optical fibre.

[0012] Due to the fact that laser light guided by the optical fibre is used to heat the chamber for the material to be deposited, the dimensions of the end piece can be significantly smaller than the dimensions of the commonly available effusion cells. In particular, the cross-section of the chamber for the material to be deposited may be comparable to, or even preferably smaller than, the cross-section of the optical fibre without an acrylic cover layer. The optical fibre typically has a circular cross-section, wherein the chamber for the material to be deposited can also have a circular crosssection, and in this case the diameters of the components may be compared instead of the cross-sections. Alternatively, the chamber for the material to be deposited may also have a different cross-section shape. The diameter of the optical fibre without the acrylic cover layer is typically in the lower hundreds of pm, typically 125 pm. The diameter of the chamber for the material to be deposited can thus be also smaller than 125 pm, more preferably smaller than 100 pm, and the dimension (diameter) of the entire end piece can be also smaller than 1 mm, i.e. significantly smaller than the conventional effusion cells, the dimensions of which are an order of magnitude larger (units to tens of centimetres). This allows a localised deposition onto a small area of the substrate, up to an order of magnitude smaller than in the case of the commonly available effusion cells.

[0013] The small dimensions of the end piece also allow for easy integration into vacuum chambers of existing and commercially available devices, e.g., vacuum deposition apparatuses or various types of electron microscopes, etc. Thus, the effusion device according to the present invention can be used in a suitable device as needed, which saves costs, since no special modifications of these devices are required. The effusion device, or rather the end piece thereof, occupies a significantly smaller space under the pole piece of the electron column compared to the existing diffusion cells, which ensures the existence of a common operating point. This makes it possible to make operando measurements with an electron microscope (in situ, during deposition), which is problematic with standard effusion cells. It is also possible to use the effusion device simply in combination with other analytical methods and equipment available in the electron microscope (signal detectors, ion source (FIB), gas injection system (GIS), scanning probe microscope (SPM), etc.). In a scanning electron microscope, the effusion device can be used, for example, to coat non-conductive samples and thus significantly improve imaging capabilities.

[0014] Moreover, the actual manufacture of the effusion device, or of the end piece, is also cheaper compared to the commonly available effusion cells, as it can be made using processes known in the semiconductor industry, for example, by using dry etching, wet etching and lithography. These processes can produce a large number of identical parts simultaneously. Savings can also be made on the material to be deposited, since a smaller amount of material is sufficient to fill the effusion device according to the present invention, specifically to fill the chamber for the material to be deposited, than in the case of existing effusion cells. The pure material needed for deposition is often very expensive. Thanks to the supply of the laser light by the optical fibre, the end piece with the material to be deposited does not have to be fixed in the vacuum chamber rigidly, typically at a large distance from the substrate, but it is instead possible (e.g., by attachment to a manipulator) to place it close to the substrate. As a result of that, the deposition using the effusion device does not require the same vacuum level as the conventional effusion cells, wherein pressure in the order of 10’1Pa or less is sufficient. This also reduces operating costs and allows the use of the effusion device even for devices that are not designed to create a very high vacuum level. The effusion device can thus also be placed, for example, in environmental electron microscopes or microreactors located within electron microscopes used for operando studies of processes on surfaces.

[0015] The effusion device according to the present invention also does not require cooling for the use thereof, which would otherwise increase its dimensions and make the construction thereof more complicated and expensive. In contrast to heating by means of a resistive electric body, heating by means of laser light is also suitable for materials with a high melting temperature, and costly heating by the impact of accelerated electrons can be abandoned due to the fact that there is no need to provide a higher level of vacuum in the vacuum chamber at all when using the effusion device according to the present invention.

[0016] Laser light can be used to irradiate the end piece locally to heat the chamber for the material to be deposited, even to very high temperatures (> 1000 °C). A laser with a suitable power and wavelength selected according to the material of which the end piece is made, e.g., according to the absorption of the selected material at a given wavelength, can be preferably used for heating. For example, if the end piece is made of silicon, a laser with a wavelength of 532 nm, often available in laboratories, can be used, due to the sufficient absorption of silicon at this wavelength. Alternatively, the end piece can be made of a different heat-resistant material, e.g., tantalum, ceramics, molybdenum or tungsten. For example, the wavelength may also be selected so that the laser light passes through the material of the end piece and is significantly absorbed by the material to be deposited intended to be heated in the end piece. The material to be deposited can typically be e.g., gallium, silver, tin, but possibly any other material as required. In the following part of the summary of the invention, various preferred possible embodiments of the end piece will be described in more detail; however, in general, the chamber for the material to be deposited is heated by the laser light delivered to the end piece by an optical fibre. The output end of the optical fibre may, for example, be embedded in the end piece and may be in direct contact with the end piece material, or it may be embedded in the end piece but may be offset from the end piece material by a certain distance. Alternatively, in a less preferred embodiment, however, the optical fibre does not have to be in contact with the end piece at all, and for heating it is sufficient if the laser light is guided to the end piece, i.e., the laser beam can only be directed at the end piece, whether by directing the optical fibre or by directing the laser beam itself after it leaves the output end of the optical fibre.

[0017] Thus, for deposition of the selected material, the effusion device can be simply placed in the vacuum chamber by placing at least the end piece with the chamber for the material to be deposited into the vacuum chamber. The laser light source and the fibre coupling system can remain outside the vacuum chamber. The material to be deposited is placed into the chamber for the material to be deposited (this can preferably be done before the end piece is inserted into the vacuum chamber) and the substrate on which the material is to be deposited is placed into the vacuum chamber. The laser light is applied to the end piece to heat the material to be deposited to a high temperature (> 1000 °C) and then it vaporises or sublimates (if vapour is formed without the solid material passing through the liquid phase). The released vapour atoms of the material to be deposited are then falling onto the cooler surface of the substrate via effusion flow, where they form a deposited thin layer.

[0018] Only one optical fibre can be used to guide the laser light from the laser light source to the end piece, a part of which will be outside the vacuum chamber and a part will be in the vacuum chamber. The optical fibre can then be introduced into the vacuum chamber using a vacuum bushing. Alternatively, however, multiple individual optical fibres may be used that are interconnected in sequence, wherein the individual optical fibres may be implemented as the same type of optical fibre (e.g., a solid optical fibre), but also as different types of optical fibres (e.g., solid vs. hollow optical fibre). Outside the vacuum chamber, for example, a first solid optical fibre may be used to guide the laser light from the fibre coupling system to the vacuum bushing, and inside the vacuum chamber; for example, a second solid optical fibre may be used to guide the laser light from the vacuum bushing to the end piece. In the vacuum bushing, both these optical fibres are precisely positioned in relation to each other to ensure the best possible transmission of laser light between them.

[0019] The optical fibre is preferably inserted into the end piece with its output end. The installation of the optical fibre into the end piece ensures good compactness, but also the disassembly of the entire effusion device, as well as reliable guiding of laser light from the laser light source to the end piece, and thus more efficient heating of the chamber for the material to be deposited. Alternatively, the optical fibre can also be connected to the end piece in a way other than by inserting it into the end piece. The insertion or other connection of the optical fibre and the end piece is preferred because the optical fibre not only serves the function of guiding the laser light, but also helps to mechanically attach the end piece into the vacuum chamber, e.g., so that the optical fibre can be attached to the manipulator in the vacuum chamber.

[0020] Preferably, the end piece comprises a chamber for the optical fibre separated from the chamber for the material to be deposited, wherein the optical fibre is inserted into the chamber for the optical fibre. The embodiment of the end piece with separate chambers is very practical, as it allows to fill the chamber for the material to be deposited with the selected material, regardless of whether or not the optical fibre is already inserted in the chamber for the optical fibre. At the same time, the partition between both chambers allows a reliable heat transfer caused by the impact of the laser light. The cross-section (diameter) of the chamber for the material to be deposited is preferably smaller than the cross-section (diameter) of the chamber for the optical fibre, which allows for the smallest possible footprint of the deposited material and a well- localized deposition. Alternatively, the cross-section of the chamber for the material to be deposited may be the same or even larger than the cross-section of the chamber for the optical fibre, but such an embodiment is not preferred as it may not provide as efficient heating of the material and as much localized deposition.

[0021] Alternatively, however, the end piece does not have to comprise separate chambers for the material to be deposited and for the optical fibre. In principle, it is sufficient if the end piece comprises one common chamber that passes through the end piece. The end piece can thus be made, for example, in the shape of a tube (formed, for example, simply by cutting a thin-walled capillary) into which an optical fibre is inserted from one side, thus closing the chamber from one side and allowing the material to be deposited from the other side. This alternative is simpler to manufacture and more heat resistant, but allows the chamber to be filled with material only after the optical fibre is inserted into the chamber.

[0022] The end piece preferably comprises at least one distance post for offsetting the output end of the optical fibre from the material of the end piece in the longitudinal direction. The distance posts may comprise, for example, separation blocks in the form of radially inwardly directed protrusions. These separation blocks thus essentially act as a stop for the optical fibre to be positioned at a certain distance from the material of the end piece, for example at a certain distance from the partition separating the chamber for the material to be deposited and the chamber for the optical fibre. Alternatively, the offsetting of the optical fibre can also be implemented in other ways, e.g., by deforming the distance posts; however, a certain distance gap between the optical fibre and the material of the end piece in the longitudinal direction is always created. Due to this distance gap, heat flux from the hottest part of the end piece to the optical fibre is limited, and such an end piece is therefore suitable and preferred for high-temperature applications.

[0023] Preferably, the effusion device comprises a deflector placed around the end piece for directing the effusion flow. Preferably, the deflector, like the end piece, is cylindrical in shape. The deflector externally surrounds the end piece and can be attached thereto by, for example, a fastening element including a sleeve for clamping the optical fibre and a flange for attachment to the deflector. Alternatively, the deflector may be attached to the end piece by any other fastening means. Directing the effusion flux by means of the deflector allows better localised deposition and the deflector also limits propagation of thermal and light radiation in the device.

[0024] The fact that the cross-section of the chamber for the material to be deposited is preferably smaller than the cross-section of the optical fibre also contributes to the well- localized deposition. Due to small dimensions of the optical fibre, the selected material can be deposited with a smaller footprint compared to the existing effusion cells, as described above.

[0025] It is apparent that the alternatives and preferred elements described above can be combined with each other to achieve different embodiments of the effusion device, e.g., the end piece may comprise separate chambers, distance posts and a deflector, but may comprise only some of these elements, for example. In general, it can also be said that the end piece is preferably cylindrical in shape and that the chamber for the material to be deposited is preferably located in the front face of the end piece and runs axially through the centre of the end piece. However, the particular shape of the end piece, the shape or location of the chamber for the material to be deposited, and the shape or location of the chamber for the optical fibre, may also be different, provided that the laser light is allowed to reach the end piece and that reliable heating of the chamber for the material to be deposited is allowed.

[0026] The at least one optical fibre is preferably embodied as a hollow optical fibre comprising at least one capillary running in a longitudinal direction to the end piece (for example, in an embodiment of commercially available fibres with photonic crystal), in which case the effusion device further comprises a working gas tank and a supply line for supplying the working gas from the working gas tank into the hollow optical fibre. By supplying not only the laser light but also the working gas to the end piece, the working gas reacts with the heated material to be deposited or with the substrate surface to form compounds. In this way, for example, oxides can be deposited if the working gas is oxygen, nitrides if the working gas is nitrogen, etc. In general, thermally activated dissociation of molecules can occur on the warm end portion of the end piece and these active particles can subsequently form a layer on the substrate surface, or modify or etch the surface, preferably also selectively. For example, methane (CH4) decomposes at 600 °C into carbon and hydrogen. The working gas can also be changed during deposition (simply by switching the supply line to another working gas tank), which can change the composition of the deposited layer to form multilayers, e.g., Ga / GaN. Furthermore, it is possible to create, for example, SiO2 and SiN layers, or it will be possible to use the effusion device to prepare new materials.

[0027] Preferably, at least two individual optical fibres are used for guiding the laser light and the working gas to the end piece, which follow axially one after each other but have a gap between them to allow the introduction of the working gas. The connection of these optical fibres can be implemented in a vacuum bushing, which also serves to introduce gas into the hollow optical fibre. When the effusion device is used, the hollow optical fibre is thus located inside the vacuum chamber and leads from the vacuum bushing to the end piece, and the solid optical fibre is located outside the vacuum chamber and leads from the fibre coupling system to the vacuum bushing. Alternatively, the hollow optical fibre can also be used outside the vacuum chamber, as it likewise also allows the transmission of the laser light. Alternatively, only one hollow optical fibre may be used, which runs from the fibre coupling system to the end piece, provided that a working gas supply is provided. In this case, it would be possible to bring the working gas into the hollow optical fibre already in the fibre coupling system.

[0028] The hollow optical fibre can be used with any of the described end piece variants. The used optical fibres, i.e., solid optical fibre and hollow optical fibre, are known.

[0029] The effusion device further preferably comprises a manipulator for attaching the end piece to the vacuum chamber, wherein the end piece is attached to the manipulator and is movable with this manipulator. The attachment of the end piece to the manipulator allows a precise and defined movement of the end piece relative to the substrate, whether to change the position in the substrate plane or to change distance from the substrate. This enables spatially controlled and well-localized deposition of material. The manipulator is usually part of the relevant apparatuses and can thus be easily used to complement the effusion device according to the present invention. These can be e.g., motorized, but also manual manipulators of vacuum chambers, nano-manipulators of electron microscopes, etc. The incorporation of the effusion device into a scanning electron microscope thus allows immediate inspection of the properties (e.g., morphology or chemical composition) of the resulting layers.

[0030] Preferably, the end piece is attached to the manipulator via the optical fibre which is attached to the manipulator. The optical fibre thus serves not only for guiding the light, but also as a supporting element for attachment to the manipulator. Alternatively, the end piece may be attached directly to the manipulator and may not even be attached to the optical fibre. In principle, it is sufficient if the end piece is illuminated by laser light coming from the optical fibre.

[0031] The effusion device further preferably comprises at least one resonant nanostructure for locally increasing the intensity of the electromagnetic field of the laser light in the near field of this at least one resonant nanostructure. This enables the application of technologies to areas smaller than the diffraction limit of the given laser light. Particularly preferable is the use of the resonant nanostructure, or in other words, a resonant antenna, in the case where an effusion device with a hollow optical fibre is used, through which the working gas is delivered to the end piece. This allows for localized dissociation of the working gas molecules only, and advantageously for modification or etching of the substrate surface in a significantly confined area compared to the variant with thermal dissociation on a laser-heated hot part of the end piece.

[0032] The resonant nanostructure is preferably a part of the end piece. For example, the resonant nanostructure may be formed on a deflector, if the end piece comprises one, or alternatively on a separate supporting element for the resonant structure. The supporting element for the resonant nanostructure may be designed, for instance, as a platform bridging the chamber for material to be deposited, advantageously on the front surface of the end piece. Alternatively, the resonant nanostructure may also be formed in another location. The resonant nanostructure may be formed, for example, using lithographic techniques.

[0033] Alternatively, the effusion device may comprise more than just one end piece or more respective optical fibres, or multiple identical effusion devices may be placed in the vacuum chamber when used in the vacuum chamber. This configuration allows for gradual deposition of different materials, e.g., creation of the so-called multilayers.

[0034] Description of Drawings

[0035] The summary of the invention is further explained by exemplary embodiments thereof, which are described by means of the accompanying drawings, in which:

[0036] Fig. 1 schematically shows an effusion device according to the present invention in the first exemplary embodiment;

[0037] Fig. 2 schematically shows an effusion device according to the present invention in the first exemplary embodiment, where the effusion device is placed in a vacuum chamber;

[0038] Fig. 3a shows an end piece in the first exemplary embodiment with a solid optical fibre inserted in a spatial view; Fig. 3b shows the end piece in the first exemplary embodiment with the solid optical fibre inserted in a longitudinal section;

[0039] Fig. 4a shows the end piece in the second exemplary embodiment with the solid optical fibre inserted in a spatial view;

[0040] Fig. 4b shows the end piece in the second exemplary embodiment with the solid optical fibre inserted in a longitudinal section;

[0041] Fig. 5 schematically shows the effusion device according to the present invention in the first exemplary embodiment, where the effusion device is placed in the vacuum chamber;

[0042] Fig. 6a shows the end piece in the third exemplary embodiment with the hollow optical fibre inserted in a spatial view;

[0043] Fig. 6b shows the end piece in the third exemplary embodiment with the hollow optical fibre inserted in a longitudinal section;

[0044] Fig. 7a shows the end piece in the fourth exemplary embodiment with the hollow optical fibre inserted in a spatial view;

[0045] Fig. 7b shows the end piece in the fourth exemplary embodiment with the hollow optical fibre inserted in a longitudinal section; and

[0046] Fig. 8 shows the end piece in the fifth exemplary embodiment with the hollow optical fibre inserted in a spatial view.

[0047] Exemplary Embodiments of the Invention

[0048] The invention will be further explained by reference to the exemplary embodiments thereof with reference to the relevant drawings.

[0049] Example 1 :

[0050] In the first exemplary embodiment, as shown in Fig. 1 to Fig. 3b, the effusion device comprises a laser light source 1, an optical fibre 2, a fibre coupling system 3 for introducing the laser light from the laser light source 1 into the optical fibre 2, and an end piece 4. In the first exemplary embodiment, the end piece 4 comprises a chamber 5 for the material to be deposited and also a chamber 6 for the optical fibre 2, as will be described in more detail below.

[0051] As shown schematically in Fig. 1 or Fig. 2, a laser light beam (indicated by dashed line) emerges from the laser light source 1 and is introduced into an input end of the optical fibre 2 by means of the fibre coupling system 3. The fibre coupling system 3 for introducing laser light into the optical fibre 2 is known in the art, and one skilled in the art is able to implement such a fibre coupling system 3 in various embodiments. For example, the fibre coupling system 3 comprises a part for mechanical attachment of the optical fibre 2 and a three-axis micro-positioning system provided with an objective lens. This makes it possible to focus the laser light into a sufficiently small area and position it exactly in the centre of the optical fibre 2. By this optical fibre 2, the laser light is guided on the principle of total reflection to the output end of the optical fibre 2, which is inserted into the end piece 4. Specifically, the optical fibre 2 is inserted by its output end into the chamber 6 for the optical fibre 2, as shown in Fig. 3b in a longitudinal section through the optical fibre 2 and the end piece 4.

[0052] The end piece 4 is cylindrical in the first exemplary embodiment, wherein the chamber 5 for the material to be deposited is made in the front surface of the end piece 4 and the chamber 6 for the optical fibre 2 is made in the rear surface of the end piece 4. By the front surface of the end piece 4 is meant the surface with which the end piece 4 faces the substrate 10 when used in the vacuum chamber 8. The chamber 5 for the material to be deposited and the chamber 6 for the optical fibre 2 have circular crosssection and are arranged coaxially in the end piece 4, for example, wherein the diameter of the chamber 5 for the material to be deposited is in this embodiment smaller than the diameter of the chamber 6 for the optical fibre 2. The diameter of the chamber 6 for the optical fibre 2 corresponds to the diameter of the optical fibre 2; better said, it is slightly larger than the diameter of the optical fibre 2 to allow the optical fibre 2 to be inserted into the chamber 6 for the optical fibre 2. As can also be seen from Fig. 3b, in this exemplary embodiment, there remains a certain partition between the chamber 5 for the material to be deposited and the chamber 6 for the optical fibre 2, formed by the material of the end piece 4. In other words, the chamber 5 for the material to be deposited and the chamber 6 for the optical fibre 2 are separated from each other. It can also be seen from the longitudinal section according to Fig. 3b that in this exemplary embodiment, the optical fibre 2 is implemented as a solid optical fibre 2, i.e., as an optical fibre 2 that does not comprise a cavity. As an example, a commercially available solid optical fibre 2 comprising three basic parts - a core, cladding and a coating layer - is used. In this type of fibre, light propagates through the core by total reflection at the core-cladding interface, with the refractive index of the core material being higher than that of the cladding material. For example, the core, as well as the cladding, is made of quartz glass, wherein the core material is suitably doped to achieve a higher refractive index. The acrylic coating layer serves as a protection of the core and the cladding against mechanical damage or against humidity of the surrounding environment. The diameter of the optical fibre 2 including the acrylic coating layer is approximately 270 pm. However, the acrylic coating layer is removed near the end piece 4 (i.e., at the output end of the optical fibre 2) and the diameter of the optical fibre (core + cladding) is 125 pm.

[0053] For localized deposition of the material, the above-described effusion device is placed in the vacuum chamber 8, such that at least the end piece 4 is placed in the vacuum chamber 8. As shown schematically in Fig. 2, in the first exemplary embodiment, the laser light source 1 is located outside the vacuum chamber 8, as well as the fibre coupling system 3 and a portion of the optical fibre 2. The optical fibre 2 is introduced into the vacuum chamber 8 by means of the vacuum bushing 7, and its remaining part is thus inside the vacuum chamber 8. The effusion device further comprises a manipulator 9 for moving the end piece 4 within the vacuum chamber 8. A precisely defined movement of the manipulator 9 relative to the vacuum chamber 8 ensures a change in the position of the end piece 4 relative to the substrate 10, whether a change in the position of the end piece 4 in the plane of the substrate 10 or a change in the distance of the end piece 4 from the substrate 10. This allows for spatially controlled and well-localized deposition of the material stored in the end piece 4, specifically in the chamber 5 for the material to be deposited. As an example, the end piece 4 is attached to the manipulator 9 via the optical fibre 2, i.e., the optical fibre 2 is inserted into the end piece 4 and the manipulator 9 is attached to the optical fibre 2. The optical fibre 2 thus serves not only for laser guiding the light, but also as a supporting element for attachment to the manipulator 9. By way of example, the vacuum chamber 8 is the vacuum chamber 8 of an electron microscope, specifically, e.g., the vacuum chamber 8 of a scanning electron microscope, and the manipulator 9 is a nanomanipulator provided on this electron microscope.

[0054] When the laser light source 1 is switched on, the laser light is guided through the optical fibre 2 to the end piece 4, where it exits the output end thereof and strikes the material of the end piece 4. The impact of the laser light on the end piece 4 causes it to heat up, wherein the heat spreads through the partition and walls of the end piece 4 all the way up to the separate chamber 5 for the material to be deposited. This heats the material stored in the chamber 5 for the material to be deposited to a high temperature (> 1000 °C), which then evaporates or sublimates (if vapour is formed without the solid material passing through the liquid phase). For this reason, the end piece 4 is made of a heat-resistant material, for example silicon, tantalum, ceramics, molybdenum, or tungsten. A tunable 1 .5 W laser with a wavelength of 532 nm is used for heating, due to the advantageous absorption of the silicon material at this wavelength.

[0055] The released vapour atoms of the material to be deposited are then falling onto the cooler surface of the substrate 10 via effusion flow, where they form a deposited thin layer. A certain level of vacuum is required in the vacuum chamber 8 for deposition, but a lower level of vacuum is sufficient here compared to the state of the art. By way of example, pressures of the order of 10’1Pa or less are used.

[0056] Example 2:

[0057] In the second exemplary embodiment, the effusion device is made in the same way as in the first exemplary embodiment, except that the end piece 4 is made differently. In the second exemplary embodiment of the end piece 4, shown in Fig. 4a and Fig. 4b, which corresponds to the second exemplary embodiment of the effusion device, the end piece 4 comprises the chamber 5 for the material to be deposited, which also serves for insertion of the optical fibre 2. Thus, the end piece 4 does not comprise separate chamber 5 for the material to be deposited and the chamber 6 for the optical fibre 2. The chamber 5 for the material to be deposited is implemented as a cavity passing through the entire end piece 4, i.e., from the front surface thereof to the rear surface thereof. In other words, the end piece 4 is in this exemplary embodiment implemented in the form of a tube.

[0058] The diameter of the chamber 5 for the material to be deposited corresponds to the diameter of the optical fibre 2; better said, it is slightly larger than the diameter of the optical fibre 2 to allow the optical fibre 2 to be inserted into the chamber 5 for the material to be deposited. As can be seen in Fig. 4b, by inserting the optical fibre 2 into the end piece 4, the chamber 5 for the material to be deposited is closed from the rear side, which allows the material to be retained in this chamber 5 for the material to be deposited. In order to prevent the optical fibre 2 from being completely threaded / passed through the end piece 4, the end piece 4 is deformed at a certain point (not shown in the figure).

[0059] Example 3:

[0060] In the third exemplary embodiment, the effusion device is implemented in the same way as in the first exemplary embodiment, except that it comprises two optical fibres, wherein at least one optical fibre, namely the optical fibre used in the section from the vacuum bushing 7 to the end piece 4, is implemented as a hollow optical fibre 2, and in particular with the difference, that the effusion device further comprises a working gas tank 11 and a supply line 12 for supplying the working gas into the hollow optical fibre 2, as shown in Fig. 5. The embodiment of the end piece 4 is also different, as can be seen in Fig. 6a and Fig. 6b.

[0061] Thus, unlike the previous two exemplary embodiments, the vacuum bushing 7 also provides optical coupling of the solid optical fibre 2, which is located outside the vacuum chamber 8, with the hollow optical fibre 2, which is located inside the vacuum chamber 8. The vacuum bushing 7 also provides for the introduction of working gas from the supply line 12 into the hollow optical fibre 2. In the vacuum bushing 7, the solid optical fibre 2 and the hollow optical fibre 2 are coaxially arranged in a transition chamber pressurized with the admitted working gas, which is vacuum-sealed from the external atmosphere and the vacuum chamber 8 (except for the capillaries 13 of the hollow optical fibre). There is a gap between the ends of the coaxially arranged optical fibres 2 to allow the working gas to pass into the hollow optical fibre 2. The supply line 12 is exemplarily a supply tube. As an example, oxygen is used as the working gas, which allows the deposition of an oxide layer that is formed as a result of the reaction of oxygen with the heated material to be deposited, or with its vapours.

[0062] The hollow optical fibre 2 differs in principle from the solid optical fibre 2 used in the previous two exemplary embodiments in that it comprises at least one capillary 3, i.e., a thin cavity passing through the optical fibre in the longitudinal direction. This capillary 13 allows the passage of the working gas through the hollow optical fibre 2. In addition to the working gas conduction, the hollow optical fibre 2 is of course also adapted for guiding the light and exemplarily comprises a core, a cladding and a coating layer, as already described for the solid optical fibre 2.

[0063] As shown in Fig. 6a and Fig. 6b, the end piece 4 in the third exemplary embodiment comprises the chamber 5 for the material to be deposited and the chamber 6 for the optical fibre, which are separated from each other by the partition, similarly to the first exemplary embodiment of the end piece 4. The chamber 5 for the material to be deposited is made in the front surface of the end piece 4 and the chamber 6 for the optical fibre 2 is made in the rear surface of the end piece 4. However, the difference compared to the end piece 4 according to the first exemplary embodiment is that the chamber 6 for the optical fibre 2 is not defined by the material of the end piece 4 along its entire circumference, but it is defined by distance posts 14, which are best seen in Fig. 6a. The distance posts 14 allow the optical fibre 2 to remain longitudinally offset from the material of the end piece 4 after the optical fibre 2 has been inserted by its output end into the chamber 6 for the optical fibre. This is exemplarily implemented by the distance posts 14 being provided with separation blocks 18, i.e., essentially protrusions against which the output end of the optical fibre 2 is stopped. As can be seen in Fig. 6b, this leaves a distance gap 15 between the output end of the hollow optical fibre 2 and the partition of the end piece 4. Thanks to that, this 4 end piece is suitable for high temperature applications.

[0064] Example 4:

[0065] In the fourth exemplary embodiment, the effusion device is made in the same way as in the third exemplary embodiment, except that the end piece 4 is made differently. In the fourth exemplary embodiment of the end piece 4, shown in Fig. 7a and Fig. 7b, which corresponds to the fourth exemplary embodiment of the effusion device, the end piece 4 additionally comprises a deflector 16.

[0066] The deflector 16 has a cylindrical shape which is open from the front side and which comprises an opening in the rear surface into which the optical fibre 2 is inserted. The diameter of the deflector 16 is greater than the diameter of the end piece 4, wherein the deflector 16 is attached to the end piece 4 and the optical fibre 2 such that the deflector 16 is located coaxially around the end piece 4 which it covers from the outside. By way of example, the deflector 16 is attached to the end piece 4 and the optical fibre 2 by a fastening element 17. This fastening element 17 comprises a sleeve for clamping the optical fibre 2 and a flange for attachment to the deflector 16. The deflector 16 allows the effusion flow of material to be directed to a more precisely localized area and also limits further propagation of thermal and light radiation in the vacuum chamber 8 in which the effusion device is used.

[0067] Further, the effusion device according to the present invention can also be implemented in further exemplary embodiments, for example in embodiments combining some of the above-described examples. Other possible alternatives also follow from the section "Summary of the Invention".

[0068] Example 5:

[0069] In the fifth exemplary embodiment, the effusion device is made in the same way as in the third exemplary embodiment (i.e., it comprises two optical fibres 2, wherein at least one optical fibre 2, specifically the optical fibre 2 used in the section from the vacuum bushing 7 to the end piece 4, is implemented as a hollow optical fibre 2), except that the end piece 4 is made differently. In this fifth exemplary embodiment, the end piece 4 is made in the same way as in the second exemplary embodiment (i.e., in the form of a tube), except that it further comprises a resonant nanostructure 19.

[0070] As can be seen in Fig. 8, the resonant nanostructure 19 is exemplarily formed on a supporting element 20 for the resonant nanostructure 19. The supporting element 20 for the resonant nanostructure 19 bridges the chamber 5 for the material to be deposited on the front surface of the end piece 4, i.e., on the surface with which the end piece 4 faces the substrate 10 when used in the vacuum chamber 8. Due to the resonant nanostructure 20, there is a local increase in the intensity of the electromagnetic field of the laser light in its near field, which can be utilized for localized dissociation of the working gas molecules and for modifying and etching the surface of the substrate 10 in a small area. Industrial Applicability

[0071] The above-described effusion device can be used for localized deposition of various materials in vacuum chambers of various instruments, e.g., in vacuum chambers of environmental electron microscopes or microreactors placed within electron microscopes used for operando study of surface processes. The effusion device can also be used, for example, for repairing damaged electrical contacts in microelectronics or for creating structures by maskless lithography.

[0072] List of Reference Signs

[0073] 1 laser light source

[0074] 2 optical fibre

[0075] 3 fibre coupling system

[0076] 4 end piece

[0077] 5 chamber for the material to be deposited

[0078] 6 chamber for the optical fibre

[0079] 7 vacuum bushing

[0080] 8 vacuum chamber

[0081] 9 manipulator

[0082] 10 substrate

[0083] 11 working gas tank

[0084] 12 supply line

[0085] 13 capillary

[0086] 14 distance post

[0087] 15 distance gap

[0088] 16 deflector

[0089] 17 fastening element

[0090] 18 separation block

[0091] 19 resonant nanostructure

[0092] 20 supporting element for resonant structure

Claims

CLAIMS1. An effusion device for localized deposition for use in a vacuum chamber (8), characterized in that it comprises an end piece (4) having a chamber (5) for a material to be deposited, wherein the effusion device further comprises a laser light source (1) for heating the material to be deposited, at least one optical fibre (2) for guiding the laser light from the laser light source (1 ) to the end piece (4), and an fibre coupling system (3) for introducing the laser light from the laser light source (1 ) into the at least one optical fibre (2).

2. The effusion device according to claim 1 , characterized in that the optical fibre (2) is inserted by the output end thereof into the end piece (4).

3. The effusion device according to claim 2, characterized in that the end piece (4) comprises a chamber (6) for the optical fibre (2) separated from the chamber (5) for the material to be deposited, wherein the optical fibre (2) is inserted into the chamber (6) for the optical fibre (2).

4. The effusion device according to any one of the preceding claims 2 or 3, characterized in that the end piece (4) comprises at least one distance post (14) for offsetting the output end of the optical fibre (2) from the material of the end piece (4) in the longitudinal direction.

5. The effusion device according to any one of the preceding claims, characterized in that it comprises a deflector (16) arranged around the end piece (4) for directing the effusion flow.

6. The effusion device according to any one of the preceding claims, characterized in that the cross-section of the chamber (5) for the material to be deposited is smaller than the cross-section of the optical fibre (2).

7. The effusion device according to any one of the preceding claims, characterized in that the at least one optical fibre (2) is made as a hollow optical fibre (2) comprising at least one capillary (13) extending in a longitudinal direction to the end piece (4), wherein the effusion device further comprises a working gas tank(11 ) and a supply line (12) for supplying the working gas from the working gas tank (11 ) to the hollow optical fibre (2).

8. The effusion device according to any one of the preceding claims, characterized in that it further comprises a manipulator (9) for attaching the end piece (4) into the vacuum chamber (8), wherein the end piece (4) is attached to the manipulator (9) and is movable with this manipulator (9).

9. The effusion device according to claim 8, characterized in that the end piece (4) is attached to the manipulator (9) via the optical fibre (2) which is attached to the manipulator (9).

10. The effusion device according to any one of the preceding claims, characterized in that it further comprises at least one resonant nanostructure (19) for locally increasing the intensity of electromagnetic field of laser light in the near field of this at least one resonant nanostructure (19).

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