GB2583951A

GB2583951A - Apparatus

Info

Publication number: GB2583951A
Application number: GB1906851.9A
Authority: GB
Inventors: Van Baarle Gertjan; Groot Irene; Saedi Mehdi; Sjardin Arthur; De Voogd Marc
Original assignee: LEIDEN PROBE MICROSCOPY BV; Universiteit Leiden
Current assignee: LEIDEN PROBE MICROSCOPY BV; Universiteit Leiden
Priority date: 2019-05-15
Filing date: 2019-05-15
Publication date: 2020-11-18
Also published as: WO2020229040A1; GB201906851D0

Abstract

An apparatus 20 for processing a sample 38 comprises a chamber for containing a process gas, a vision, detection or radiation device 26a, 26b, 26c and at least one solid barrier member 28a, 28b, 30a, 30b. The apparatus may be a chemical vapour deposition apparatus and is suitable for performing a film coating process. The solid barrier member acts to break or disrupt a convective vortex of the process gas into a plurality of smaller convective vortices 50 to increase a convective flow path of the gas. Exposure of the device to heat transported by the gas and material deposited by the gas is reduced. A cooling device, preferably a heat sink or coolant conduit, may be provided to cool the barrier member. The barrier member preferably includes at least one protruding member projecting from a wall of the chamber into the interior space. The device may be a light source, an x-ray source, an electromagnetic radiation detector, an electron or ion beam source, a particle radiation detector, a window or a scanning probe.

Description

APPARATUS

This invention relates to an apparatus that comprises a chamber for containing a gas, and a functional device configured to be located in, or connected to, an interior space of the chamber.

It is known to carry out in-situ inspection of a sample inside a processing chamber. This allows characterisation of the sample without removing it from the processing chamber, which is particularly useful for in-operando investigation of the sample.

According to an aspect of the invention, there is provided an apparatus comprising: a chamber for containing a first gas; a functional device configured to be located in, or connected to, an interior space of the chamber; and at least one solid barrier member arranged inside the chamber to, in use, constrain a convective flow pattern of the first gas inside the chamber so as to increase a length and modify a profile of a convective flow path of the first gas inside the chamber.

It will be understood that the location of the functional device in the interior space of the chamber refers to the location of part or the whole of the functional device in the interior space of the chamber. It will also be understood that the connection of the functional device to the interior space of the chamber refers to the functional device having physical access to the interior space of the chamber.

Heating an object inside a gas-containing chamber increases the temperature of the surrounding gas in the immediate vicinity of the heated object. This creates a natural convective flow which causes the first gas inside the chamber to move along a convective flow path, thereby transporting heat from the heated object to other parts of the chamber.

In addition, an object inside the chamber may undergo evaporation or sublimation that results in the presence of evaporated or sublimated material in the first gas inside the chamber, thereby transporting the evaporated or sublimated material along the convective flow path to the other parts of the chamber. Evaporation or sublimation of the object may be caused by the aforementioned heating of the object.

Furthermore, the first gas itself may undergo reaction or decomposition while it travels along the convective flow path, which in turn causes deposition of material on the functional device. Such deposition of material may occur, for example, by way of chemical vapour deposition.

Even more so, the convective flow path of the first gas may arise as a result of, or may be influenced by, forced motion of the first gas generated by an external source, such as a pump or fan. Such forced motion of the first gas is referred to as a forced convective flow.

As the first gas travels along the convective flow path to the functional device, the functional device is exposed to the heat and/or material transported/deposited by the first to gas and thereby runs the risk of its characteristics, in particular its functional and structural characteristics, being adversely affected by the heat and/or the material transported/deposited by the first gas. For example, the functional device may experience temporary malfunction or permanent damage (such as thermal shock, breakage and warpage) caused by excessive heating of the functional device and/or by material deposition on the functional device, which may have the detrimental effect of preventing the functional device from carrying out its intended function.

The above arrangement of the or each solid barrier member in the apparatus of the invention therefore protects the functional device from the heat and/or material transported/deposited by the first gas and thereby prevents or reduces unwanted overheating of the functional device and/or unintentional material deposition on the functional device. More particularly, the arrangement of the or each solid barrier member inside the chamber provides one or more physical constraints that, in use, directs the first gas inside the chamber to follow a specific convective flow pattern inside the chamber that increases the length and modifies the profile of the convective flow path of the first gas inside the chamber. This in turn allows for increased reductions in temperature, material deposition rate and/or vapour concentration of the first gas travelling along the convective flow path by the time it reaches the functional device.

In contrast, omission of the or each solid barrier member from the chamber results in a comparatively shorter convective flow path of the first gas inside the chamber and thereby increases the risk of unwanted overheating of the functional device and/or unintentional material deposition on the functional device.

It will be understood that the or each barrier member may be arranged inside the chamber to, in use, constrain a natural convective flow pattern, a forced convective flow pattern, or both natural and forced convective flow patterns, of the first gas inside the chamber so as to increase the length and modify the profile of the convective flow path of the first gas inside the chamber.

It will also be understood that, in embodiments of the invention in which the chamber is a vacuum chamber, the first gas may take the form of vapour from a heated object.

In a preferred embodiment of the invention, the or each barrier member may be arranged inside the chamber to, in use, deform a convective vortex of the first gas inside the chamber and/or break a convective vortex of the first gas inside the chamber into a plurality of smaller convective vortices so as to increase the length and modify the profile of the convective flow path of the first gas inside the chamber.

In addition to constraining the convective flow pattern of the first gas inside the chamber, the or each barrier member may be arranged inside the chamber to serve other purposes, examples of which are set out as follows.

In a first example, the or each barrier member may be arranged inside the chamber to, in use, provide a deposition surface for one or more substances present in, or originating from, the first gas travelling along the convective flow path. This provides a reliable means for reducing the vapour concentration and/or material deposition rate of the first gas as it travels along the convective flow path.

In a second example, the or each barrier member may be arranged inside the chamber to, in use, provide a cooling surface for the first gas travelling along the convective flow path.

This provides a reliable means for reducing the temperature of the first gas as it travels along the convective flow path.

The apparatus may further include a cooling device for cooling the or each barrier member. The cooling device may include, for example, a heat sink and/or a coolant conduit for carrying a coolant. This further improves the capability of the or each barrier member to reduce the vapour concentration, material deposition rate and/or temperature of the first gas as it travels along the convective flow path.

The configuration of the or each barrier member may vary depending on the shape and dimensions of the chamber and the relative positions of the object and the functional device.

The or each barrier member may vary in shape and dimension so long as it acts as a barrier that is capable of physically constraining a convective flow pattern of the first gas inside the chamber so as to increase the length and modify the profile of the convective flow path of the first gas inside the chamber. For example, the or each barrier member may include at least one protruding member that projects into the interior space of the chamber.

The or each barrier member may be configured to be integral with a wall of the chamber. Configuring the or each barrier member in this manner enhances the robustness of the or each barrier member and thereby improves the reliability of the apparatus.

The or each barrier member may be configured to be separate from a wall of the chamber. Configuring the or each barrier member in this manner not only enables retro-fitting of the or each barrier member to an existing chamber in order to provide the apparatus of the invention, but also permits replacement of the or each barrier member with a different barrier member to suit a different range of applications of the apparatus.

The apparatus may include an object that is contained inside the chamber. For such an apparatus containing the object inside the chamber, the or each barrier member may be arranged inside the chamber to, in use, constrain the convective flow pattern of the first gas inside the chamber so as to increase the length and modify the profile of the convective flow path of the first gas between the object and the functional device.

The object inside the chamber may be a sample, or may be a structural or functional component of the apparatus.

The configuration of the functional device may vary so long as it is designed to perform a function that is associated with the interior space of the chamber. Examples of functions of the functional device include, but are not limited to, processing, measurement, sensing, detection and object manipulation in the interior space of the chamber.

In embodiments of the invention, the functional device may be a vision, detection or radiation device.

The invention beneficially reduces the risk of excessive heating of the vision, detection or radiation device and/or excessive material deposition on the vision, detection or radiation device. This in turn enables the vision, detection or radiation device to carry out in-situ inspection and characterisation of an object inside the chamber without any adverse impact on the performance of the functional device, such as its operational sensitivity and accuracy. In particular, the invention usefully prevents unintentional material deposition on the vision, detection or radiation device that could obscure the viewing, detection or radiation capability of the vision, detection or radiation device. This is particularly useful for a wide range of applications such as chemical studies of catalysis processes, high-temperature materials science, design and optimisation of coating processes, and the like.

Examples of vision, detection or radiation devices include, but are not limited to: to * an electromagnetic radiation source, e.g. a visible light source, an ultra-violet light source, an infra-red light source, an X-ray source; * an electromagnetic radiation detector, e.g. a visible light detector, an ultra-violet light detector, an infra-red light detector, an X-ray detector, a spectrometer; * a particle radiation source, e.g. an electron beam source or an ion beam source; * a particle radiation detector, e.g. an electron beam detector or an ion beam detector; * a window through which electromagnetic or particle radiation may be guided into and/or out of the interior space of the chamber; * a non-contact or contact probe, e.g. a scanning probe.

It will be appreciated that the foregoing examples of functional devices are not intended to be limiting but instead are intended to illustrate the wide range of functional devices that can be used in the invention.

In further embodiments of the invention, the or each barrier member may be arranged outside of a viewing, detection or radiation path of the vision, detection or radiation device. This ensures that the or each barrier member does not block the viewing, detection or radiation path of the vision, detection or radiation device, thus permitting in-situ inspection and characterisation of an object inside the chamber.

The apparatus may further include a heating source. The heating source may be configured to provide heat by way of thermal radiation, thermal conduction, or electron bombardment.

In embodiments of the invention, the apparatus may further include a gas conduit for connection to a gas source containing a second gas, wherein the gas conduit may be arranged to, in use, direct the second gas to flow inside the chamber so as to form a shield between the first gas and the functional device. In such embodiments, the second gas may be, for example, an inert gas, such as argon.

The gas conduit may be configured to provide an additional mechanism to protect the functional device from the heat and/or material transported/deposited by the first gas to prevent or reduce unwanted overheating of the functional device and/or unintentional material deposition on the functional device. The second gas can not only act as a gas curtain that physically keeps the hot and/or vapour-rich gas away from the functional device, but also acts to cool the functional device to prevent or reduce overheating caused by thermal radiation emitted by the heated object.

In further embodiments of the invention, the apparatus may further include a gas conduit for connection to a gas source containing a second gas, wherein the gas conduit may be arranged to, in use, direct the second gas to constrain a convective flow pattern of the first gas inside the chamber so as to increase a length and modify a profile of a convective flow path of the first gas inside the chamber. In such embodiments, the gas conduit may be arranged to, in use, direct the second gas to deform a convective vortex of the first gas inside the chamber and/or break a convective vortex of the first gas inside the chamber into a plurality of smaller convective vortices so as to increase the length and modify the profile of the convective flow path of the first gas inside the chamber. In such embodiments, the second gas may be, for example, an inert gas, such as argon.

The configuration of the gas conduit in this manner provides a further mechanism by which the functional device is protected from the heat and/or material transported/deposited by the first gas in order to prevent or reduce unwanted overheating of the functional device and/or unintentional material deposition on the functional device. More particularly, the directed flow of the second gas cooperates with the or each solid barrier member to provide one or more physical constraints that, in use, directs the first gas inside the chamber to follow a specific convective flow pattern inside the chamber that increases the length and modifies the profile of the convective flow path of the first gas inside the chamber. This in turn further enhances the reductions in temperature, material deposition rate and/or vapour concentration of the first gas travelling along the convective flow path by the time it reaches the functional device.

The inventors have found that care must be taken regarding the flow parameters of the second gas in order to ensure that the aforementioned protective functions are carried out without adversely affecting the normal operation of the apparatus. If the flow of the second gas is too low, it is not effective in forming the shield between the first gas and the functional device and in constraining the convective flow pattern of the first gas inside the chamber. If the flow of the second gas is too high, it not only may lead to unintentional cooling of the interior space of, and therefore any object contained inside, the chamber but also may affect the convective flow pattern of the first gas in a manner that is detrimental to the apparatus.

The apparatus may include a plurality of functional devices.

The or each barrier member and the gas conduit may be configured in the apparatus so that, in use, the or each barrier member and/or the directed flow of the second gas constrain the convective flow pattern of the first gas inside the chamber to protect the at least one of the plurality of functional devices from the heat and/or material transported/deposited by the gas while the gas conduit forms the gas curtain to separately protect the at least one other of the plurality of functional devices from the heat and/or material transported/deposited by the first gas. This is particularly advantageous when multiple functional devices are arranged and/or connected in different locations with respect to the interior space of the chamber.

The gas conduit may be connected to a gas source that is internal or external to the chamber.

The configuration of the gas conduit may vary depending on the shape and dimensions of the chamber.

In embodiments employing the use of the gas conduit, the gas conduit may be arranged to, in use, direct the second gas to flow in the vicinity of, or adjacent to, the functional device. In such embodiments, the gas conduit may be arranged to, in use, direct the second gas to flow in contact with the functional device.

Arranging the gas conduit in this manner provides a reliable means for controlling the temperature of the functional device to prevent overheating caused by thermal radiation emitted by the heated object.

Optionally at least part of the gas conduit may be formed in, or by, the or each barrier member. This enables the or each barrier member to be designed to firstly physically constrain the convective flow pattern of the first gas inside the chamber and secondly guide the flow of the second gas to provide a further physical constraint to the convective flow pattern of the first gas inside the chamber.

Alternatively the gas conduit may be separate from the or each barrier member.

The gas conduit may be connected to a gas source containing a mixture of the first gas and the second gas, wherein the gas conduit may be arranged to, in use, direct the mixture to flow inside the chamber. Alternatively, the gas conduit may be connected to a gas source containing the first gas, wherein the first gas is the same as the second gas.

In embodiments of the invention, the apparatus may be configured as a processing apparatus, and the chamber may be configured as a process chamber for containing a process gas. In such embodiments, the processing apparatus may be configured for carrying out a process on the object. It is envisaged that the processing apparatus may be configured to carry out a wide range of processes, such as reactions, decomposition, etching, and any other process involving a process gas. For example, the apparatus may be configured for carrying out a coating process, such as a film coating process (e.g. chemical vapour deposition).

During the processing step, the object may undergo heating and/or evaporation or sublimation, and the functional device may be directly exposed to the process gas. This creates the risk of the functional device being exposed to heat and/or material transported/deposited by the process gas that may adversely affect the characteristics of the functional device. The invention removes or mitigates this risk and enables the functional device to reliably carry out in-operando inspection and characterisation of the object that is undergoing processing, which allows for the optimisation of the processing step.

In embodiments of the invention in which the apparatus is configured as a processing apparatus and employs the use of the gas conduit, the apparatus may include a gas source containing a mixture of the process gas and the second gas, wherein the gas conduit may be arranged to, in use, direct the mixture to flow inside the chamber. The second gas, such as an inert gas, may be selected to minimise its impact on the processing of the object.

In other embodiments of the invention in which the apparatus is configured as a processing apparatus and employs the use of the gas conduit, the apparatus may include a gas source containing the process gas, wherein the gas conduit may be arranged to, in use, direct the process gas to flow inside the chamber. In such embodiments, the process gas may be the same as the second gas.

It will be appreciated that the use of the terms "first" and "second", and the like, in this patent specification is merely intended to help distinguish between similar features (e.g. the first and second gases) unless otherwise specified, and is not intended to indicate the relative importance of one feature over another feature unless otherwise specified.

A preferred embodiment of the invention will now be described, by way of a non-limiting example, with reference to the accompanying drawings in which: Figures 1 and 2 show schematically a cross-sectional view of an apparatus according to an embodiment of the invention; Figures 3 and 4 show comparative examples that omit the solid barrier members of the apparatus of Figures 1 and 2; and Figures 5a to 5c, 6a to 6c and 7a to 7c show simulations of flow velocity and heat maps of an interior space of a reactor, and material deposition rate on an X-ray window of the reactor.

The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic form in the interests of clarity and conciseness.

The following embodiment of the invention is described with reference to a chemical vapour deposition (CVD) apparatus having a plurality of functional devices comprising an optical detector, an optical window, an X-ray source, an X-ray detector and an X-ray window, but it will be appreciated that the following embodiment of the invention is applicable mutafis mutandis to other types of apparatuses that comprise a chamber for containing a gas, and other types of functional devices configured to be located in, or connected to, an interior space of the chamber. Examples of other types of apparatuses and functional devices are described throughout the specification.

An apparatus according to an embodiment of the invention is shown in Figure 1, and is designated generally by the reference numeral 20.

The apparatus 20 is a CVD apparatus 20, and comprises a chamber 22, a plurality of functional devices 24a,24b,26a,26b,26c, a plurality of solid barrier members 28a,28b,30a,30b, and a gas conduit 32a,32b.

The chamber 22 is a reactor 22 that defines an enclosed interior space that is filled with a gas, such as argon. Side walls 26c of the reactor 22 are made from an X-ray transparent material (such as beryllium). This allows X-rays to pass through the reactor's side walls 26c into and out of the interior space of the reactor 22.

A heater stage 34 is arranged in the centre of a bottom wall 36 (or a floor 36) of the interior space of the reactor 22. The heater stage 34 provides a platform onto which a sample 38 may be placed. The heater stage 34 includes a heater element (not shown) that is operable to increase the temperature of the heater stage 34 in order to heat the sample 38 placed thereon by way of thermal conduction. It is envisaged that, in other embodiments of the invention, the heating source may be configured to heat the object by way of thermal radiation or electron bombardment.

A first of the functional devices includes an optical detector 24a and an optical window 24b. The optical window 24b is installed in a top wall 40 (or a ceiling 40) of the reactor 22 and above the heater stage 34. The optical detector 24a is arranged outside the reactor 22 and above the optical window 24b so that the optical detector 24a is configured to view the heater stage 34, or any sample 38 placed on the heater stage 34, through the optical window 24b. The optical detector 24a is preferably configured to perform optical microscopy or Raman spectroscopy.

A second of the functional devices includes an X-ray source 26a, an X-ray detector 26b and an X-ray window 26c. Both the X-ray source 26a and the X-ray detector 26b are arranged on opposite sides outside the side walls 26c of the reactor 22. By virtue of being made of an X-ray transparent material, the side walls 26c of the reactor 22 define the X-ray window 26c. X-rays from the X-ray source 26a on one side of the reactor 22 can enter the interior space of the reactor 22 via the X-ray window 26c. The X-rays scatter when they pass through the sample 38 on the heater stage 34. The resulting scattered X-rays can exit the interior space of the reactor 22 via the X-ray window 26c and towards the X-ray detector 26b on the opposite side of the reactor 22.

A first of the barrier members 28a,28b is integral with the top wall 40 of the reactor 22. The first barrier member includes two annular protruding members 28a,28b that project from the top wall 40 into the interior space of the reactor 22. The annular structure of the protruding members 28a,28b of the first barrier member allows the first barrier member to surround the optical window 24b installed in the top wall 40. In the first barrier member, the protruding members 28a,28b have different diameters such that one of the protruding members 28b is arranged to surround the other of the protruding members 28a.

A second of the barrier members 30a,30b is integral with the floor 36 of the reactor 22. The second barrier member includes two annular protruding members 30a,30b that project from the floor 36 into the interior space of the reactor 22. The annular structure of the protruding members 30a,30b of the second barrier member allows the second barrier member to surround the heater stage 34 located in the centre of the floor 36. In the second barrier member, the protruding members 30a,30b have different diameters such that one of the protruding members 30b is arranged to surround the other of the protruding members 30a.

It is envisaged that, in other embodiments of the invention, either or both of the barrier members may be configured to be separate from a wall of the reactor. It is also envisaged that, in still other embodiments of the invention, the CVD apparatus may include a single barrier member, or may include three or more barrier members. It is further envisaged that, in still further embodiments of the invention, each barrier member may include a different number of annular protruding members.

The extent to which the protruding members 28a,28b,30a,30b of the barrier members project into the interior space of the reactor 22 are limited by the positions of the sample 38 and the functional devices 24a,24b,26a,26b,26c.

The first barrier member is shaped to arrange its protruding members 28a,28b outside of a viewing path that extends between the sample 38 and the optical window 24b. This is so that they do not block the viewing path 42 between the sample 38 and the optical 30 window 24b.

The first and second barrier members are shaped to arrange their protruding members 28a,28b,30a,30b outside of a radiation path 44 that extends between the X-ray window 26c and the sample 38, and outside of a detection path 46 that extends between the X-ray window 26c and the X-ray detector 26b. This is so that they do not block the radiation path 44 for X-rays travelling from the X-ray source 26a to the sample 38, and the detection path 46 for scattered X-rays travelling from the sample 38 to the X-ray detector 26b.

The arrangement of the protruding members 28a,28b,30a,30b of the barrier members therefore do not interfere the operation of the functional devices 24a,24b,26a,26b,26c to carry out in-situ optical and X-ray inspection and characterisation of the sample 38.

The gas conduit comprises a gas inlet 32a and a gas outlet 32b, each of which defines an annular channel. The gas inlet 32a and gas outlet 32b are located in the top wall 40 of the reactor 22. The gas inlet 32a is arranged to surround the optical window 24b. The gas outlet 32b is arranged to surround the gas inlet 32a. The gas inlet 32a and gas outlet 32b are arranged between the optical window 24b and the first barrier member. The annular structures of the gas inlet 32a and gas outlet 32b allow the gas inlet 32a and gas outlet 32b to be installed in the top wall 40 without blocking the viewing path 42 between the sample 38 and the optical window 24b.

The arrangement of the gas inlet 32a and gas outlet 32b therefore do not interfere with the operation of the optical detector 24a to carry out in-situ optical inspection and characterisation of the sample 38.

A first, upper end of the gas inlet 32a is connected to a gas source (not shown) that contains an inert gas, such as argon. A second, lower end of the gas inlet 32a is located in the vicinity of the optical window 24b, and is shaped to curve in the direction of the optical window 24b. In use, the inert gas flows from the gas source into the first end of the gas inlet 32a, flows through the gas inlet 32a from the first end to the second end, and then exits the second end to impinge on the optical window 24b before being directed towards the sample 38 on the heater stage 34. Finally the inert gas leaves the interior space of the reactor 22 by exiting through the gas outlet 32b. The configuration of the gas inlet 32a allows the inert gas to exit the second end of the gas inlet 32a and flow into the interior space of the reactor 22 in a way that not only results in the formation of a shield, or gas curtain 48, between the sample 38 and the optical window 24b but also directs the inert gas to flow towards the X-ray window 26c.

In the embodiment shown, the gas outlet is formed partly by the protruding members 28a,28b. It is envisaged that, in other embodiments, the gas conduit may be formed separately of the barrier members.

In the embodiment shown, the gas source is external to the reactor 22. It is envisaged that, in other embodiments of the invention, the gas source may be internal to the reactor.

Preferably the inert gas has a high atomic number and excellent heat conductance.

During the use of the CVD apparatus 20 to carry out a CVD process, a molten copper substrate 38 of 1 cm diameter is placed on the heater stage 34, and the copper substrate 38 is heated to a high temperature. The copper substrate 38 is exposed to a carbon-containing precursor gas (such as ethylene or benzene gas), which for example may be introduced via a gas injection needle connected to a source containing the precursor gas. Carbon-containing molecules are adsorbed on the surface of the copper substrate 38, followed by decomposition of the adsorbed molecules to form carbon atoms that either remain on the surface or dissolve into the copper substrate 38. This enables the formation of a graphene film on the surface of the copper substrate 38 through graphene nucleation and growth mechanisms that are known in the art.

It is envisaged that, in other embodiments, the copper substrate may be solid and/or the size of the copper substrate may vary.

During the CVD process, the functional devices 24a,24b,26a,26b,26c are used to carry out in-operando optical and X-ray inspection and characterisation of the copper substrate 38. This allows for the monitoring and optimisation of the CVD process in order to increase graphene film formation quality and efficiency.

During the CVD process, the heated copper substrate 38 emits heat by way of thermal radiation, and also increases the temperature of the surrounding gas in the immediate vicinity of the copper substrate 38. The latter creates a natural convective flow which causes the gas inside the reactor 22 to move along a convective flow path, thereby transporting heat from the heated copper substrate 38 to other parts of the interior space of the reactor 22.

In addition, during the CVD process, the heated copper substrate 38 may undergo evaporation. For example, copper evaporates at the rate of 400pm per hour at 1100°C. This results in the presence of copper vapour in the gas inside the reactor 22, thereby transporting the copper vapour along the convective flow path to the other parts of the interior space of the reactor 22.

As the hot and vapour-rich gas travels along the convective flow path to the other parts of the interior space of the reactor 22, the optical and X-ray windows 24b,26c are exposed to direct contact with the heat and copper vapour transported by the gas. In addition, the optical window 24b is exposed to thermal radiation emitted by the copper substrate 38. Furthermore, as the precursor gas travels along the convective flow path, the precursor gas may undergo reaction or decomposition that results in chemical vapour deposition of carbon material onto the optical and X-ray windows 24b,26c. This exposes the optical and X-ray windows 24b,26c to the risk of temporary malfunction or permanent damage due to thermal shock, breakage and warpage caused by overheating, and also the risk of copper/carbon material deposition on the surfaces of the optical and X-ray windows 24b,26c that obscure the optical and X-ray windows 24b,26c. This in turn has the detrimental effect of preventing the functional devices 24a,24b,26a,26b,26c from carrying out the in-operando optical and X-ray inspection and characterisation of the copper substrate 38.

The provision of the barrier members and the gas conduit in the CVD apparatus 20 protects the functional devices 24a,24b,26a,26b,26c from the heat and evaporated copper material transported by the gas, the carbon material deposited by the gas, and the thermal radiation by preventing or reducing unwanted overheating of the optical and X-ray windows 24b,26c and unintentional copper/carbon material deposition on the optical and X-ray windows 24b,26c, which is described as follows.

Firstly, the arrangement of the protruding members 28a,28b,30a,30b of the barrier members in the CVD apparatus 20 has the effect of constraining, or modifying, a convective flow pattern of the gas inside the reactor 22 so as to increase a length and modify a profile of a convective flow path of the gas between the copper substrate 38 and the X-ray window 26c. This is preferably achieved by the protruding members 28a,28b,30a,30b of the barrier members being shaped to form physical constraints that breaks a convective vortex of the gas inside the reactor 22 into a plurality of smaller convective vortices 50 so as to increase the length and modify the profile of the convective flow path of the gas between the copper substrate 38 and the X-ray window 26c, as shown in Figure 2.

In addition to constraining the convective flow pattern of the gas inside the reactor 22, the surfaces of the protruding members 28a,28b,30a,30b of the barrier members provide deposition surfaces for the copper vapour present in the gas travelling along the convective flow path, deposition surfaces for the carbon material arising from reaction or decomposition of the precursor gas travelling along the convective flow path, and cooling surfaces for the gas travelling along the convective flow path. This has the effect of reducing the copper vapour concentration, copper and carbon deposition rates and temperature of the gas travelling along the convective flow path by the time it reaches the X-ray window 26c, thus providing effective protection for the X-ray window 26c.

Optionally the CVD apparatus 20 may further include a plurality of cooling devices, each of which is built into or attached to each barrier member. The cooling device may be in the form of a heat sink and/or a coolant conduit for carrying a coolant. This provides control over the temperature of the barrier members to be at low levels in order to improve the capability of the barrier members to reduce the copper vapour concentration, copper and carbon deposition rates and the temperature of the gas as it travels along the convective flow path.

Secondly, the gas conduit enables the formation of the gas curtain 48 that physically keeps the rising hot and vapour-rich gas away from the optical window 24b, but also cools down the optical window 24b to prevent or reduce overheating caused by thermal radiation, thus providing effective protection for the optical window 24b. In this regard, the inert gas is preferably kept at low temperatures, such as room temperature.

Thirdly, the arrangement of the gas conduit in the CVD apparatus 20 has the effect of constraining, or modifying, a convective flow pattern of the gas inside the reactor 22 so as to increase a length and modify a profile of a convective flow path of the gas between the copper substrate 38 and the X-ray window 26c. This is preferably achieved by the inert gas being directed to flow towards the X-ray window 26c that enables the flowing inert gas to deform a convective vortex of the gas inside the reactor 22 so as to increase the length and modify the profile of the convective flow path of the gas between the copper substrate 38 and the X-ray window 26c.

In this way, the directed flow of the inert gas cooperates with the barrier members to provide one or more physical constraints that, in use, directs the gas inside the reactor 22 to follow a specific convective flow pattern inside the reactor 22 that increases the length and modifies the profile of the convective flow path of the gas inside the reactor 22.

Optionally the gas source connected to the gas inlet may contain: * a different type of inert gas; * a mixture of the process gas and the inert gas; or * the process gas that replaces the inert gas.

When the gas source contains a mixture of the process gas and the inert gas, the gas conduit is configured to, in use, direct the mixture to flow inside the reactor 22.

The configuration of the CVD apparatus 20 therefore enables the creation of a specific gas flow pattern in the interior space of the reactor 22 using the barrier members 28a,28b,30a,30b and gas conduit 32a,32b to protect the optical and X-ray windows 24b.26c from high temperatures and material deposition arising from the CVD process, and thereby beneficially maintains the optical and X-ray windows 24b,26c in a clean and transparent state that enables the functional devices 24a,24b,26a,26b,26c to carry out in-operando optical and X-ray inspection and characterisation of the copper substrate 38 during the CVD process, without any adverse impact on their performance.

Figure 3 shows a comparative example of a CVD apparatus in which the barrier members are omitted. Figure 4 shows a comparative example of a CVD apparatus in which the barrier members and gas conduit are omitted.

As seen in both Figures 3 and 4, omission of the solid barrier members from the interior space 52 of the reactor results in a comparatively shorter convective flow path 54 of the gas inside the reactor and reduced deposition and cooling surface areas for the gas travelling along the convective flow path. This increases the risk of unwanted overheating of the X-ray window 56 and unintentional material deposition on the X-ray window 56.

As seen in Figure 4, the further omission of the gas conduit not only exposes the optical window 58 to direct contact with the hot and vapour-rich gas rising from the copper substrate 60, thus increasing the risk of unwanted overheating of the optical window 58 and unintentional material deposition on the optical window 58, but also removes the cooling of the optical window 58, thus exposing the optical window 58 to overheating due to the thermal radiation emitted by the heated copper substrate 60.

Figures 5a to 5c, 6a to 6c and 7a to 7c show simulations of the flow velocity map of the interior space of the reactor 22, the heat map of the interior space of the reactor 22, and material deposition rate on the X-ray window 26c for the case in which the reactor 22 is filled with argon and the sample 38 is a 1 cm diameter copper substrate 38 at 1100°C.

The simulations shown in Figures 5a to Sc show the conditions of the reactor 22 with an internal gas pressure of 1 bar and no flow of the inert gas through the gas conduit. The only flow in the interior space of the reactor 22 is generated by the natural convection due to the heat of the molten copper substrate 38, and is illustrated in the flow velocity map of Figure 5a.

It can be seen in Figures 5a to Sc that the optical window 24b experiences a high temperature and a high material deposition rate due to the absence of the gas curtain. It can also be seen in Figures 5a to 5c that the barrier members are effective in reducing the temperature, copper and carbon deposition rates and copper vapour concentration of the gas before it reaches the X-ray window 26c, thus providing effective protection for the X-ray window 26c. In particular, Figure 5a shows the increased length and the modified profile of the convective flow path of the gas between the heated copper substrate 38 and the X-ray window 26c, Figure 5b shows the reduction in temperature of the gas as it approaches the X-ray window 26c, and Figure 5c shows a noticeable material deposition rate on the surfaces of the protruding members 28a,28b,30a,30b of the barrier members that has the effect of reducing the material deposition rate on the X-ray window 26c.

The simulations shown in Figures 6a to 6c show the conditions of the reactor 22 with an internal gas pressure of 1 bar and a flow of the inert gas through the gas conduit in addition to the natural convective flow due to the heat of the molten copper substrate 38. The addition of the flow of the inert gas alongside the natural convective flow is illustrated in the flow velocity map of Figure 6a.

It can be seen in Figures 6b and 6c that the optical window 24b does not become hotter than 50°C and stays clean and transparent due to the presence of the gas curtain 48, thus providing effective protection for the optical window 24b. It can also be seen in Figures 6a to 6c that the barrier members and the flow of the inert gas are effective in reducing the temperature, copper and carbon deposition rates and copper vapour concentration of the gas before it reaches the X-ray window 26c, thus providing effective protection for the X-ray window 26c. In particular, Figure 6a shows the increased length and the modified profile of the convective flow path of the gas between the heated copper substrate 38 and the X-ray window 26c, Figure 6b shows the reduction in temperature of the gas as it approaches the X-ray window 26c, and Figure 6c shows a noticeable material deposition rate on the surfaces of the protruding members 28a,28b,30a,30b of the barrier members that has the effect of reducing the material deposition rate on the X-ray window 26c.

The simulations shown in Figures 7a to 7c show the conditions of the reactor 22 with an internal gas pressure of 20 mbar and a flow of the inert gas through the gas conduit, in addition to the natural convective flow due to the heat of the molten copper substrate 38.

The flow of the inert gas alongside the natural convective flow is illustrated in the flow velocity map of Figure 7a, which is different from the gas flow patterns illustrated in Figures 5a and 6a.

It can be seen in Figures 7b and 7c that the optical window 24b does not become hotter than 50°C and stays clean and transparent due to the presence of the gas curtain 48, thus providing effective protection for the optical window 24b. It can also be seen in Figures 7a to 7c that the barrier members and the flow of the inert gas are effective in reducing the temperature, copper and carbon deposition rates and copper vapour concentration of the gas before it reaches the X-ray window 26c, thus providing effective protection for the X-ray window 26c. In particular, Figure 7a shows the increased length and the modified profile of the convective flow path of the gas between the heated copper substrate 38 and the X-ray window 26c, Figure 7b shows the reduction in temperature of the gas as it approaches the X-ray window 26c, and Figure 7c shows a noticeable material deposition rate on the surfaces of the protruding members 28a,28b,30a,30b of the barrier members that has the effect of reducing the material deposition rate on the X-ray window 26c.

It can therefore be seen in Figures 5a to 5c, 6a to 6c and 7a to 7c that the setup of the CVD apparatus 20 successfully prevents any noticeable degradation of the optical and X-ray windows 24b,26c due to overheating or loss of transparency caused by material deposition. In particular, the inventors have successfully used the setup of the CVD apparatus 20 for over 500 hours under conditions similar to the conditions stated with reference to Figures 6a to 6c.

It will be appreciated that the protective mechanisms provided by the barrier members and gas conduit apply mutatis mutandis to a set-up of the CVD apparatus in which there are no intermediate windows between the optical and X-ray devices and the heated copper substrate, that is to say the optical and X-ray devices are either located in or connected to the interior space of the reactor.

It will also be appreciated that the CVD apparatus may be adapted so that the barrier members and gas curtain are configured to protect the same functional device. For example, the barrier members and the gas conduit may be configured in the CVD apparatus so that, in use, the barrier members and/or the directed flow of the inert gas constrain the convective flow pattern of the gas inside the reactor to protect a functional device from the heat and/or material transported/deposited by the gas while the gas conduit forms the gas curtain to protect the same functional device from the heat and/or material transported/deposited by the gas.

The above embodiment of the invention was described with reference to a CVD process to form a graphene film on a molten copper substrate. It will be appreciated that the above embodiment of the invention applies mutatis mutandis to other types of coating processes and other types of coating materials.

It will also be appreciated that the above embodiment of the invention applies mutafis mutandis to other types of processing apparatuses, other types of processing gases, and other types of processes.

Claims

CLAIMS1. An apparatus comprising: a chamber for containing a first gas; a functional device configured to be located in, or connected to, an interior space of the chamber; and at least one solid barrier member arranged inside the chamber to, in use, constrain a convective flow pattern of the first gas inside the chamber so as to increase a length and modify a profile of a convective flow path of the first gas inside the chamber.
2. An apparatus according to Claim 1 wherein the or each barrier member is arranged inside the chamber to, in use, deform a convective vortex of the first gas inside the chamber and/or break a convective vortex of the first gas inside the chamber into a plurality of smaller convective vortices so as to increase the length and modify the profile of the convective flow path of the first gas inside the chamber.
3. An apparatus according to any one of the preceding claims wherein the or each barrier member is arranged inside the chamber to, in use, provide a deposition surface for one or more substances present in, or originating from, the first gas travelling along the convective flow path.
4. An apparatus according to any one of the preceding claims wherein the or each barrier member is arranged inside the chamber to, in use, provide a cooling surface for the first gas travelling along the convective flow path.
5. An apparatus according to Claim 4 further including a cooling device for cooling the or each barrier member.
6. An apparatus according to Claim 5 wherein the cooling device includes a heat sink and/or a coolant conduit for carrying a coolant.
7. An apparatus according to any one of the preceding claims wherein the or each barrier member includes at least one protruding member that projects into the interior space of the chamber.
8. An apparatus according to any one of the preceding claims wherein the or each barrier member is configured to be integral with, or separate from, a wall of the chamber.
9. An apparatus according to any one of the preceding claims including an object that is contained inside the chamber, wherein the or each barrier member is arranged inside the chamber to, in use, constrain the convective flow pattern of the first gas inside the chamber so as to increase the length and modify the profile of the convective flow path of the first gas between the object and the functional device.
10. An apparatus according to any one of the preceding claims wherein the functional device is a vision, detection or radiation device. 10
11. An apparatus according to Claim 10 wherein the vision, detection or radiation device includes: * an electromagnetic radiation source; * a visible light source, an ultra-violet light source, an infra-red light source, or an X-ray source; * an electromagnetic radiation detector * a visible light detector, an ultra-violet light detector, an infra-red light detector, an X-ray detector, or a spectrometer; * a particle radiation source; * an electron beam source or an ion beam source; * a particle radiation detector; * an electron beam detector or an ion beam detector; * a window through which electromagnetic or particle radiation may be guided into and/or out of the interior space of the chamber; * a non-contact or contact probe or * a scanning probe.
12. An apparatus according to Claim 10 or Claim 11 wherein the or each barrier member is arranged outside of a viewing, detection or radiation path of the vision, detection or radiation device.
13. An apparatus according to any one of the preceding claims further including a heating source.
14. An apparatus according to any one of the preceding claims further including a gas conduit for connection to a gas source containing a second gas, wherein the gas conduit is arranged to, in use, direct the second gas to flow inside the chamber so as to form a shield between the first gas and the functional device.
15. An apparatus according to any one of the preceding claims further including a gas conduit for connection to a gas source containing a second gas, wherein the gas conduit is arranged to, in use, direct the second gas to constrain a convective flow pattern of the first gas inside the chamber so as to increase a length and modify a profile of a convective flow path of the first gas inside the chamber.
16. An apparatus according to Claim 15 wherein the gas conduit is arranged to, in use, direct the second gas to deform a convective vortex of the first gas inside the chamber and/or break a convective vortex of the first gas inside the chamber into a plurality of smaller convective vortices so as to increase the length and modify the profile of the convective flow path of the first gas inside the chamber.
17. An apparatus according to any one of Claims 14 to 16 wherein the gas conduit is arranged to, in use, direct the second gas to flow in the vicinity of, or adjacent to, the functional device.
18. An apparatus according to Claim 17 wherein the gas conduit is arranged to, in use, direct the second gas to flow in contact with the functional device.
19. An apparatus according to any one of Claims 14 to 18 wherein at least part of the gas conduit is formed in, or by, the or each barrier member.
20. An apparatus according to any one of Claims 14 to 19 wherein the gas conduit is connected to a gas source containing a mixture of the first gas and the second gas, wherein the gas conduit is arranged to, in use, direct the mixture to flow inside the chamber.
21. An apparatus according to any one of Claims 14 to 19 wherein the gas conduit is connected to a gas source containing the first gas, wherein the first gas is the same as the second gas.
22. An apparatus according to any one of the preceding claims wherein the apparatus is configured as a processing apparatus, and the chamber is configured as a process chamber for containing a process gas.
23. An apparatus according to Claim 22 wherein the processing apparatus is configured for carrying out a process on an object.
24. An apparatus according to Claim 22 or Claim 23 wherein the apparatus is configured for carrying out a coating process.
25. An apparatus according to Claim 24 wherein the apparatus is configured for carrying out a film coating process.