Angular velocity measurement system for substrate used in epitaxial deposition reactor

Abstract

A method for measuring and controlling the angular velocity of a substrate in a semiconductor film deposition epitaxial reactor is disclosed. The invention also discloses an assembly suitable for carrying out the method, and a reaction chamber and a reactor comprising the assembly. In particular, although not exclusively, the above assemblies, reaction chambers, and methods can be used in hot wall cross flow reactors for epitaxial deposition of silicon, silicon carbide, or gallium nitride.

Description

Technical Field

[0001] The present invention relates to the field of epitaxial deposition of semiconductor films on substrates, and in particular to a method for measuring and controlling the rotation speed of a substrate in a reaction chamber of an epitaxial deposition reactor, and components suitable for performing the method. Background Art

[0002] Semiconductor films made by epitaxial growth, also called epilayers, are formed by deposition in a reaction chamber of a reactor. The deposited material can be the same as the substrate, or include a different semiconductor with specific desired qualities. Epitaxy techniques allow control of the crystal structure formed on the substrate and improvement of the characteristics of the epilayer surface, making them suitable for the manufacture of highly complex microprocessors and memory devices.

[0003] To ensure uniformity in thickness and doping concentration of the epitaxial layers deposited in the reaction chamber, the semiconductor substrate is placed on a support system that rotates during film deposition. It is important that the rotation speed of the substrate is predetermined and constant during the deposition process to reduce thickness deviations and doping concentration non-uniformities.

[0004] In hot-wall reaction chambers, where the walls are actively heated and temperatures can reach 1800°C, controlling the rotation speed of the substrate support system becomes a particularly challenging task due to the high temperatures of the reaction chamber where the rotating substrate resides.

[0005] In practice, hot wall reaction chambers can be used, for example, for epitaxial deposition of silicon (Si), silicon carbide (SiC) or gallium nitride (GaN) on substrates made of the same or different materials. In the above non-limiting examples, the chambers typically operate at temperatures between 800-1800°C, depending on the chemistry.

[0006] Available techniques for measuring and controlling the rotational speed of the support system are affected by the actuation mechanism of the support system.

[0007] For example, the substrate support system can be rotated by mechanical actuation means, which allows precise control of their rotation speed. However, this solution has a negative impact on the manufacturing, maintenance and assembly operations of the reactor, since the number of interconnected mechanical parts involved and their placement increase the overall complexity of the system.

[0008] Alternatively, the substrate support system can be set to rotate via a gas flow (usually an inert gas) that lifts the device and engages with it to enable it to rotate unhindered within the reaction chamber. To this end, the bottom surface of the support system can be provided with a set of grooves that extend toward its outer edge and / or spirally extend, as described in WO2007010568, WO2004053188A1, WO2004053189A1, WO2005121417A1. The grooves provide a preferential path for the inert gas to flow. As a result, the support system is subjected to a torque that sets it to rotate.

[0009] Although the velocity and flow rate of the gas flow can be read and controlled via a suitable gas flow control device (GFCD), such as a mass flow controller (MFC), these values ​​are not clearly related to the rotation speed of the support system. Therefore, they cannot be used to determine the revolutions per minute (rpm) with the required accuracy, since this quantity is also affected by other factors, such as the placement of the support system and / or the accumulation of deposits.

[0010] US2022411961 describes a device and method for measuring and adjusting the angular velocity of a support system in a hot wall reactor, wherein the system includes a disc-shaped element that is arranged to rotate via an argon gas flow. The disc-shaped element is equipped with a shaft extending below the base of the reaction chamber and has a protrusion, the rotation of which is suitable for detection by a pyrometer or a thermal imaging camera. This method of measuring the rotational speed has been proven to be accurate and allows a constant rotational speed to be maintained with a variation of less than 1rpm. However, the presence and placement of the shaft and other structural elements described in the cited prior art may hinder maintenance operations and increase the downtime of the reactor.

[0011] It would therefore be desirable to provide a system that allows for accurate measurement and control of substrate angular velocity within a hot wall reaction chamber of an epitaxial reactor without substantially interfering with maintenance operations and ensuring uniformity of film deposition. Summary of the invention

[0012] The object of the present invention is to overcome the disadvantages of the prior art. In particular, it is an object of the present invention to provide a method for accurately measuring and controlling the angular velocity of a substrate in an epitaxial reactor for semiconductor film deposition and an assembly suitable for performing said method. Another object of the present invention is to provide such an assembly and method, which ensure uniformity of film deposition (particularly but not exclusively, in a hot wall reaction chamber of an epitaxial reactor) without substantially hindering reactor maintenance operations.

[0013] The primary objectives set out above are achieved by the invention as described in the accompanying claims, which form an integral part of the present description.

[0014] This summary is provided to introduce some concepts in a simplified form. These concepts are further described in detail in the detailed description of the example embodiments disclosed below. This summary is not intended to identify the key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a hot wall reactor is provided.

[0016] Figure 2(a) shows a detail of a lifting element and Figure 2(b) shows a portion of the base of a reaction chamber of an assembly according to the invention.

[0017] Figure 3 A support system according to an embodiment of the present invention is depicted.

[0018] It should be understood that the elements in the drawings are shown for simplicity and clarity and are not necessarily drawn to scale. For example, the size of some elements in the drawings may be exaggerated relative to other elements to help improve the understanding of the illustrated embodiments of the present disclosure. DETAILED DESCRIPTION

[0019] Although certain embodiments and examples are disclosed below, those skilled in the art will appreciate that the invention extends beyond the specifically disclosed embodiments and / or uses of the invention and their obvious modifications and equivalents. Therefore, it is intended that the scope of the disclosed invention should not be limited by the specifically disclosed embodiments described below.

[0020] In one aspect, the invention relates to a reactor assembly suitable for epitaxial deposition of semiconductor films. The assembly comprises a reaction chamber having a base, the base being provided with a receiving area having a plurality of gas outlets. The outlets are connected to at least one gas conduit, which is suitable for conveying a gas flow within the reaction chamber when the assembly is in use.

[0021] The assembly further comprises a support system housed in the above-mentioned receiving area and adapted to support a substrate undergoing epitaxial deposition. The support system is rotatable about a rotation axis and comprises a lifting element.

[0022] The lifting element has a bottom surface facing the receiving area and an upper surface opposite the bottom surface. It can support at least one substrate undergoing epitaxial deposition on its upper surface. The substrate can be placed directly on the upper surface of the lifting element, or placed on other additional parts placed between them, which will be discussed further below.

[0023] As used herein, the term "substrate" may refer to any one or more underlying materials, including any one or more underlying materials that may be modified or on which a device, circuit, or film may be formed. A "substrate" may be continuous or non-continuous; rigid or flexible; solid or porous; and combinations thereof. A substrate may be in any form, such as a powder, a plate, or a workpiece. A plate-like substrate may include wafers of various shapes and sizes. A substrate may be made of semiconductor materials, including, for example, silicon, silicon germanium, silicon oxide, gallium arsenide, gallium nitride, and silicon carbide.

[0024] The lifting element is adapted to receive a gas flow from a gas outlet on its bottom surface. The gas flow causes the lifting element to: (1) lift the support system from the receiving area, and / or (2) rotate about a rotation axis perpendicular to the base of the reaction chamber. The first effect is achieved via the pressure applied to the bottom surface by the gas flow. The second effect is achieved due to the interaction of the gas flow with at least two grooves or ridges located on the bottom surface of the lifting element. The grooves or ridges are designed to provide a preferential path for the gas flow and cause continuous rotation of the support system by applying a slight torque on the support system.

[0025] The assembly according to the invention further comprises at least one pressure sensor adapted to measure and record the change of the pressure signal in the gas conduit when the lifting element rotates.The pressure sensor can be placed outside the reaction chamber, which facilitates maintenance operations and reduces the complexity of manufacturing.

[0026] The assembly may also include at least one GFCD, such as an MFC, which may be used to measure and maintain a substantially constant gas flow in the gas conduit.

[0027] A person skilled in the art will appreciate how the assembly according to the invention allows for accurate calculation and control of the rotation speed of the substrate in the reaction chamber, thereby ensuring uniform epitaxial deposition. This objective is achieved by reducing the number of mechanical elements connected to the support system compared to the prior art, thereby facilitating maintenance operations. In addition, speed measurement and control operations can be performed outside the reaction chamber, thereby increasing the reliability of the entire assembly. This is particularly important in hot wall reactors, such as those designed for Si, SiC and GaN deposition, which present a unique set of challenges due to the extremely high temperatures reached within the reaction chamber.

[0028] In fact, assuming that the gas flow in the gas conduit is approximately constant, the variation of the flow resistance is mainly related to the pressure variation in the gas conduit. When the lifting element rotates during deposition, the resistance of the bottom surface of the lifting element to the gas flow depends on the mutual positioning of the gas outlet and the grooves / ridges formed on the bottom surface.

[0029] Specifically, as the lifting element rotates, the gas flow resistance in the gas conduit decreases when the receding surface is closer to (or aligned with) the gas outlet, and the gas flow resistance increases when the protruding surface is closer to (or aligned with) the gas outlet.

[0030] Therefore, in case of constant rotation of the lifting element, the pressure inside the gas duct varies in a substantially periodic manner, so that the rotation speed of the lifting element (which is related to the angular velocity of the support system and, therefore, to the angular velocity of one or more substrates contained therein) can be inferred by monitoring the pattern and period of changes in the pressure signal inside the gas duct using a pressure sensor located outside the reaction chamber.

[0031] Typically, the CFCD will also be placed outside the reaction chamber and further upstream of the pressure sensor with respect to the gas flow direction. In order to prevent the positioning of the GFCD from influencing the pressure signal measured by the pressure sensor, such as the intensity of the pressure signal changes, holes can be placed in the gas line, locally reducing its cross-section. The holes should be located between the GFCD and the pressure sensor, preferably closer to the latter. As a result, the signal changes measured by the pressure sensor are mainly driven by the changes in the flow resistance occurring downstream of the holes in the gas conduit connected to the gas outlet, which are a result of the interaction between the gas flow and the bottom surface of the lifting element.

[0032] Note that one or more substrates may be placed in appropriately designed recesses on the upper surface of the lifting element. Alternatively, they may be placed on a substrate holder located on the upper surface of the lifting element. The holder may be integral with the lifting element, or connected or connectable to the lifting element. The substrate holder may advantageously be a removable piece to allow the substrate to be input into and output from the reaction chamber without direct contact, thereby maintaining their integrity and facilitating automated processes.

[0033] The lifting element and the substrate holder preferably have a disc-like shape, whose centres substantially coincide with the axis of rotation of the support system when the assembly is in use.

[0034] The substrate holder may advantageously be designed with annular ridges and protrusions adapted to avoid large-area planar contact with the substrate. This may prevent mechanical instability due to loss of adhesion to the substrate holder in the event of bending / bending of the substrate towards its center during deposition.

[0035] In addition, the annular flange can be placed on the substrate holder to enclose the substrate and prevent its displacement.Alternatively, the annular flange can be used to raise the substrate relative to the substrate holder or clamp the substrate thereon.

[0036] The lifting element as well as the optional substrate holder and the optional annular flange may advantageously be made of one or more materials having high sensitivity, such as graphite, to effectively reach temperatures of up to 1800° C. when subjected to a suitable electromagnetic field. The same materials may also advantageously be used for the walls of the reaction chamber (including the base) and other suitable elements of the reactor in order to achieve the same effect.

[0037] Some or all parts of the reaction chamber, such as the part corresponding to the receiving area or the part above it, can optionally be coated with a TaC layer to protect the graphite surface during cleaning. Other coatings, such as a thin layer of SiC, can be used to achieve the same or different purposes, such as preventing deposit accumulation or sealing the porous graphite surface to avoid contamination. For example, the lifting element and the support holder can advantageously be provided with a TaC coating, while the annular flange can be coated with a SiC layer.

[0038] Note that for the gas flow in the assembly according to the present invention, it is desirable to use an inert gas, such as nitrogen, argon, neon, helium, xenon or a combination thereof. Alternatively, hydrogen may be used. In order to reach multiple gas outlets, the gas flow from the gas duct may be divided into multiple gas channels. If one or more channels arrive at the base at an angle α<90°, preferably α<80°, the lifting element may be rotated more efficiently. In the case of using multiple gas ducts to reach multiple gas outlets, a similar method may be used by causing at least one separate duct to impinge on the base at an angle α<90°, preferably α<80°. Without departing from the scope of the present invention, additional outlets or ducts impinging at the same or different angles may be used to more effectively raise the lifting element.

[0039] According to one embodiment, each groove or ridge of the lifting element is a continuous segment connecting an inner end and an outer end, wherein the outer end extends outwardly (linearly, arcuately or spirally) toward the periphery of the lifting element. The inner end is thus positioned closer to the axis of rotation of the support system relative to the outer end. This design helps to guide the gas flow from the gas outlet so that the lifting element is more effectively set into rotation. The grooves or ridges can all have the same or different lengths.

[0040] According to one embodiment, in the assembly according to the invention, the bottom surface of the lifting element further comprises a number N i ≥ 2 depressions or protrusions, which may advantageously differ in shape and placement from the grooves and ridges described above. These depressions / protrusions may be arranged relative to one another so that at least once during a 360° rotation of the support system about its axis at least two depressions or protrusions are aligned with the position of at least two gas outlets, thereby generating a beat in the pressure signal, which beat may be related to the rotation speed of the lifting element.

[0041] Advantageously, all depressions or protrusions can be aligned with the positions of all the plurality of gas outlets at least once during a 360° rotation, thereby maximizing the intensity of the measurement signal variation.

[0042] Note that the grooves / ridges in the support system provide two main contributions: (i) causing a change in the pressure signal in the gas conduit when the gas flow leaves the multiple outlets, and (ii) ensuring constant rotation of the lifting element when the gas flow is received. On the other hand, the main role of the depressions / protrusions is to enhance the pressure signal changes in the gas conduit during operation. Therefore, each depression / protrusion can advantageously occupy a smaller area on the bottom surface of the lifting element relative to a single groove / ridge. Preferably, although not exclusively, the depression / protrusion can present an area equal to 0.3-3 times the area of ​​the individual gas outlets on the receiving area.

[0043] Generally, one of ordinary skill in the art can adjust the depth, thickness and size of the grooves, ridges, depressions or protrusions based on the size, weight and nominal angular velocity of the lifting element and the instrument sensitivity of the pressure sensor.

[0044] The same method can be used to determine the appropriate number of depressions or protrusions N i and the number of grooves or ridges N g In most cases, N i and N g It may be lower than or equal to 20 to avoid signal ambiguity. To ensure the stability of the lifting element during lifting and rotation, it is preferred that the number of outlets and the number of grooves / ridges are equal to or greater than three. The number of depressions / protrusions may also advantageously be equal to or greater than three and equal to the number of gas outlets.

[0045] In certain embodiments, the number of grooves or ridges N g can be an integer multiple of the number of gas outlets. In this case, an amplification of the pressure signal variation may occur. This effect can be further enhanced by optimizing the placement of the inner end of one or more grooves or ridges to align with or approach the gas outlet at least once during a 360° rotation of the support system when the assembly is in use. This is particularly useful when no depressions or protrusions are used. Note that in N g When the number of gas outlets is not an integer multiple, the signal intensity may decrease, but the signal resolution may increase.

[0046] In another embodiment, in an assembly according to the invention, the distance of the depressions or protrusions from the axis of rotation of the support system does not exceed the distance of the inner end of each groove or ridge from the axis of rotation. This means that the depressions or protrusions are placed in a region around the axis of rotation without grooves / ridges. Advantageously, if the gas outlet is placed corresponding to this surface, the lifting element can more easily raise the support system to ensure unhindered rotation.

[0047] In another embodiment, the assembly may further include: (i) at least one GFCD for controlling gas flow in the one or more gas conduits, and (ii) at least one feedback loop circuit connecting the GFCD to the pressure sensor. The feedback loop circuit may advantageously be configured to adjust the gas flow via the GFCD based on real-time input of the pressure signal so as to maintain a constant rotational speed of the support system.

[0048] Alternatively, the above assembly may further include an electronic device programmed to convert changes in the pressure signal into a rotational speed of the support system. In this case, a feedback loop circuit connects the airflow control device to the electronic device and is configured to adjust the airflow through the GFCD based on real-time input of the rotational speed signal so as to maintain a constant speed.

[0049] In any of the above embodiments, the GFCD may be an MFC or any other device suitable for achieving the same effect.

[0050] In a second aspect, the present invention relates to a reaction chamber of a reactor suitable for epitaxial deposition of semiconductor films, preferably but not exclusively a hot wall cross-flow reactor, comprising any embodiment of the components described above, and any combination or equivalent thereof.

[0051] In a third aspect, the present invention relates to a reactor comprising a reaction chamber as described above.

[0052] In a fourth aspect, the present invention relates to a method for controlling the rotational speed of a support system of an assembly as described above during operation so as to maintain a constant rotational speed of a substrate supported therein.

[0053] The method is executed when activated by a user and includes the following steps: (i) delivering a gas flow into at least one gas conduit through a GFCD; (ii) recording a pressure signal measured by a pressure sensor; (iii) converting the pressure signal into a real-time rotational speed of the support system via an electronic device and calculating the difference relative to a predetermined nominal value; (iv) adjusting the gas flow via the GFCD to minimize the difference between the converted real-time rotational speed of the support system and the predetermined nominal value; (v) sequentially repeating steps (i)-(iv) until the user provides an interrupt signal.

[0054] The illustrations presented here are not meant to be actual views of any particular material, structure, or device, but are merely idealized representations for describing embodiments of the present disclosure. In addition, the connecting lines shown in the various figures are intended to represent exemplary functional relationships and / or physical connections between the various elements. Many alternative or additional functional relationships or physical connections may exist in actual systems, and / or may not exist in some embodiments.

[0055] Figure 1A schematic example of a hot wall cross-flow reactor 1 for SiC deposition is shown, the reactor having a cylindrical geometry extending uniformly in the longitudinal direction. This type of reactor can advantageously implement the assembly and method according to the invention. The reactor has a reaction chamber 10 in which epitaxial deposition takes place, the reaction chamber being defined by an assembly of a plurality of base elements 11, 12, 13, 14 contained in an insulating cover 15 and a quartz tube 16 for flowing a cooling fluid such as water. The base elements can advantageously be made of a material with high sensitivity, such as graphite, to ensure that they can reach temperatures of up to 1800° C. when subjected to a suitable electromagnetic field. The latter can be generated by an induction coil (not shown) wound around the quartz tube.

[0056] Some or all portions of the reaction chamber may be coated with one or more layers of TaC coating to protect the susceptor element during cleaning. Other coatings may be used to achieve the same or different effects; for example, to prevent deposit buildup or to seal selected areas of the porous graphite surface and avoid contamination therefrom.

[0057] The reaction chamber has a base 100 which may be provided with an area suitable for receiving a support system for a substrate undergoing epitaxial deposition. It should be understood that the assemblies and methods according to the present invention may be advantageously implemented in other types of reactors which may differ in geometry, materials, operating conditions and chemistry from the reactors described and discussed herein.

[0058] FIG. 2( a ) provides a schematic bottom view of a lifting element 210 . FIG. 2( b ) provides an illustration of some features of a reaction chamber base 100 as viewed from a top side view according to a specific embodiment of the present invention. In FIG. 2( a ), a lifting element 210 , which may form part of a substrate support system rotatable about an axis of rotation z, has a bottom surface 250 having four grooves 261 , 262, 263, 264 designed to cause continuous rotation when receiving a gas flow. To this end, the grooves extend toward the outer edge of the lifting element. The bottom surface of the lifting element also includes two recesses 281 , 282 designed to align with two gas outlets 161 , 162 located in a receiving region of the base 100 shown in FIG. 2( b ). The base 100 is part of a base element 11 of a reactor, through which a gas conduit 150 passes, the gas conduit 150 eventually dividing into two gas channels reaching the outlets 161 , 162. During operation, the lifting element 210 is positioned with the bottom surface above the receiving region. During the rotation of the lifting element about the z-axis (dash-dotted line), the depressions on the bottom align with the gas outlets on the receiving area twice during each 360° rotation cycle, thereby producing alternating pressure changes in the gas duct that can be measured by a pressure sensor (not shown). When the support system rotates, each individual groove approaches / leaves the gas outlet and also causes a pressure change. Note that the gas from the gas outlet also allows the lifting element to rise above the receiving area. It should be understood that the number of grooves, depressions and gas outlets can vary without departing from the scope of the present invention. In particular, the use of at least three gas outlets and at least three grooves / ridges can improve the stability of the support system during its lifting and rotation during operation of the component. Using a number of depressions or protrusions equal to the number of outlets can amplify the pressure changes measured by the sensor, so they can also be advantageously selected to be equal to or greater than three.

[0059] Figure 3 A top-side view of a portion of a support system 200 having a disc-like shape according to an embodiment of the invention is shown. The support system comprises a lifting element 210 having a support holder 300 on its upper surface. The support holder has a peripheral ridge 310 to prevent a planar substrate (not shown) from adhering to its exposed surface. This allows better holding the substrate in place even if the latter undergoes slight deformations (typically bending) during epitaxial deposition. An annular flange 400 serves to further secure the substrate against lateral displacements in a plane perpendicular to the axis of rotation z.

[0060] The specific embodiments shown and described above are examples of the invention and its best mode and are not intended to limit the scope of these aspects and embodiments in any way. In fact, for the sake of brevity, conventional manufacturing, connection, preparation and other functional aspects of the system may not be described in detail.

Claims

1. An assembly of a reactor (1) suitable for epitaxial deposition of semiconductor films, comprising: - a reaction chamber (10) having a base (100) provided with a receiving area (110); said receiving area (110) being provided with a plurality of gas outlets (161, 162) connected to at least one gas duct (150), the gas duct (150) being suitable for conveying a gas flow when the assembly is in use; a support system (200) rotatable about a rotation axis (z) and adapted to support at least one substrate, comprising a lifting element (210) having a bottom surface (250) facing the receiving area and an upper surface opposite the bottom surface; wherein the support system is housed in a receiving area (110) and the lifting element is adapted to (i) receive a gas flow on a bottom surface from a gas outlet and (ii) raise the support system during rotation; the bottom surface has at least two grooves or ridges (261, 262, 263, 264) designed to cause continuous rotation of the support system; the assembly further comprises at least one pressure sensor adapted to measure and record changes in a pressure signal in a gas conduit when the gas flow hits the bottom surface of the lifting element.

2. The assembly according to claim 1, wherein The support system further comprises at least one removable substrate holder (300) placed on the upper surface of the lifting element; the substrate holder is integral with the lifting element, connected or connectable to the lifting element.

3. The assembly according to claim 2, wherein: The support system also includes at least one annular flange (400) placed on the at least one substrate holder.

4. The assembly according to any one of claims 1 to 3, wherein: Each groove or ridge of the lifting element is a continuous segment having an inner end and an outer end, the inner end being located closer to the axis of rotation of the support system than the outer end.

5. The assembly according to claim 4, wherein: The bottom surface of the lifting element also includes a number N i ≥2 depressions or protrusions (281, 282); the depressions or protrusions are arranged relative to each other so that at least two depressions or protrusions are aligned with the positions of at least two gas outlets at least once during a 360° rotation of the support system.

6. The assembly according to claim 5, wherein: The recesses or protrusions are arranged such that at least once during a 360° rotation of the support system all recesses or protrusions are aligned with the positions of the plurality of gas outlets.

7. An assembly according to claim 5 or 6, wherein: The number of the at least two grooves or ridges is N g , the number N g An integer multiple of the number of gas outlets.

8. An assembly according to any one of claims 5 to 7, wherein: The distance between the depression or protrusion and the axis of rotation of the support system is no greater than the distance between the inner end of each groove or ridge and the axis of rotation.

9. An assembly according to any one of the preceding claims, further comprising: (i) at least one air flow control device for controlling air flow in the at least one air conduit, and (ii) at least one feedback loop circuit connecting the air flow control device to the pressure sensor, wherein the feedback loop circuit is configured to adjust the air flow via the air flow control device based on a pressure signal measured by the pressure sensor so as to maintain a constant rotational speed of the support system.

10. An assembly according to any one of claims 1 to 8, further comprising electronic means for converting changes in the pressure signal measured by the pressure sensor into a rotational speed of the support system.

11. The assembly of claim 10, further comprising at least one gas flow control device for controlling gas flow in said at least one gas conduit, and at least one feedback loop circuit connecting said gas flow control device to said electronic device, wherein The feedback loop circuit is configured to adjust the airflow via the airflow control device based on the rotational speed measured by the electronic device so as to maintain a constant rotational speed of the support system.

12. An assembly according to claim 9 or 11, wherein The air flow control device is a mass flow controller.

13. An assembly according to any one of claims 1 to 8, further comprising a gas flow control device, preferably a mass flow controller.

14. A reaction chamber (10) for a reactor (1) suitable for epitaxial deposition of semiconductor films, comprising an assembly according to any one of the preceding claims.

15. A reactor (1) suitable for epitaxial deposition of semiconductor films, comprising a reaction chamber (10) according to claim 14.

16. A method for controlling the rotational speed of a support system of an assembly according to claim 1 when the assembly is used when activated by a user, the method comprising the steps of: (i) delivering a gas flow into at least one gas conduit via a gas flow control device; (ii) recording a pressure signal measured by a pressure sensor; (iii) converting the pressure signal via electronic means into a rotational speed of the support system and calculating the difference relative to a predetermined nominal value; (iv) regulating the airflow via the airflow control device to minimize the difference between the converted rotational speed of the support system and the predetermined nominal value; (v) Repeat steps (i) to (iv) sequentially until the user provides an interrupt signal.

17. Use of a pressure sensor of an assembly according to claim 1 for measuring and controlling the rotational speed of a support system.

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