MOCVD (Metal Organic Chemical Vapor Deposition) equipment and satellite disc rotating speed measuring method

Abstract

The invention provides MOCVD (Metal Organic Chemical Vapor Deposition) equipment which comprises a reaction cavity, a planetary plate for bearing a substrate is arranged in the reaction cavity, a plurality of rotating units are arranged on the planetary plate, and at least one mark is arranged on the edge of each rotating unit; the MOCVD equipment further comprises an image acquisition device used for acquiring an image of the rotating unit; the view field range of the image acquisition device at least covers part of the motion trail of the mark; the image acquisition parameter adjusting module is used for adjusting working parameters of the image acquisition device; and the image processing module is configured to calculate the actual rotation speed of the corresponding rotating unit based on the acquired marked image. The invention further provides a satellite disc rotating speed measuring method. According to the invention, the actual rotation speed of the satellite disc can be obtained, and the actual rotation speed can be used for accurately adjusting the air flow for driving the satellite disc to rotate, so that the surface temperature of the substrate meets the process requirement, and the yield of substrate processing is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor equipment, and in particular to a method for measuring the rotation speed of a MOCVD device and a satellite disk. Background Art

[0002] CVD (Chemical Vapor Deposition) refers to the process in which the reactants react chemically on the substrate surface under gaseous conditions to form a thin film. CVD equipment is a device that realizes chemical vapor deposition on the substrate surface. MOCVD (Metalorganic Chemical Vapor Deposition) equipment is a typical CVD equipment that can provide the required temperature, pressure, chemical gas composition and other conditions when growing a crystal structure for light emission on the substrate surface, such as GaN (gallium nitride).

[0003] The MOCVD equipment includes a reaction chamber, in which a rotating large graphite disk - a planetary disk is arranged. The large graphite tray is provided with a plurality of self-rotating small graphite disks - satellite disks, on which substrates can be placed. The large graphite disk is driven by a motor and its speed is controllable. The satellite disk is blown by airflow to rotate, and the rotation speed of the satellite disk is adjusted by adjusting the airflow. Due to the differences in the flow path of the airflow in the planetary disk and the fact that the airway of the airflow is prone to produce particulate matter, the continuous stability of the satellite disk's rotation is poor and the rotation speed is difficult to ensure consistency. The rotation speed of the satellite disk will affect the temperature of the satellite disk and the substrate temperature, as well as the uniformity of the thin film grown on the substrate surface. If the rotation speed of the satellite disk does not meet the process requirements, it will directly lead to a decrease in product yield.

[0004] Therefore, it is necessary to accurately measure the rotation speed of the satellite dish in order to adjust the airflow. Summary of the invention

[0005] The purpose of the present invention is to provide a method for measuring the rotation speed of a MOCVD device and a satellite disk, and to obtain the actual rotation speed of the corresponding rotating unit in real time according to the collected marked image. The present invention solves the technical problem of being unable to accurately measure the rotation speed of the rotating unit, and can accurately adjust the air flow rate driving the rotating unit to rotate according to the actual rotation speed of the rotating unit, ensuring that the substrate surface reaches the temperature required by the process, and greatly improving the yield rate of substrate processing.

[0006] In order to achieve the above object, the present invention provides a MOCVD device, the MOCVD device comprising a reaction chamber, a planetary disk for carrying a substrate is provided in the reaction chamber, a plurality of rotating units are provided on the planetary disk, and at least one mark is provided on the edge of the rotating unit;

[0007] The MOCVD device further comprises:

[0008] An image acquisition device for acquiring an image of the rotating unit; the field of view range of the image acquisition device covers at least a part of the movement trajectory of the marker.

[0009] An image acquisition parameter adjustment module for adjusting the working parameters of the image acquisition device.

[0010] An image processing module configured to calculate the actual self-rotation speed of the corresponding rotating unit based on the acquired marked image; the marked image is the image containing the marker.

[0011] Optionally, within a first time period from when the marker enters the field of view range to when it leaves the field of view range, the image acquisition device can acquire at least two marked images containing the same marker.

[0012] Optionally, the image processing module includes: an image recognition unit and a calculation unit.

[0013] The image recognition unit is configured to recognize the marked image from the acquired image and recognize the marker from the marked image.

[0014] The calculation unit is configured to: based on two adjacent marked images containing the same marker acquired within the first time period, obtain the displacement of the corresponding marker; and based on the displacement and the time interval between the two adjacent shootings, calculate the actual self-rotation speed of the corresponding rotating unit.

[0015] Optionally, the two marked images containing the same marker are respectively a first marked image and a second marked image; t1 and t2 are the acquisition times of the first marked image and the second marked image respectively, with the unit of second; t1 < t2; at times t1 and t2, the same marker has a first projection point and a second projection point on the upper surface of the planetary disk respectively; at time t1, the center of the rotating unit corresponding to the first marked image has a third projection point on the upper surface of the planetary disk; ∠A has the third projection point as the vertex angle, and the first projection point and the second projection point respectively fall on two rays of ∠A, and the unit of ∠A is radian; the actual self-rotation speed of the rotating unit corresponding to the first marked image within the time period from t1 to t2 is v, with the unit of revolutions per minute.

[0016]

[0017] Optionally, the MOCVD device further includes a position measurement device and a controller; the position measurement device is used to measure the rotation angle of the planetary disk relative to its initial position; the controller drives the image acquisition device to start or stop working based on the rotation angle.

[0018] Optionally, the image processing module determines a rotation unit corresponding to the marked image based on the rotation angle.

[0019] Optionally, different rotation units have different marks; and the image processing module determines the rotation unit corresponding to the marked image based on the identified mark.

[0020] Optionally, the rotating unit includes a satellite dish and the substrate placed on the satellite dish; the mark includes a pattern arranged on the edge of the satellite dish and / or a notch arranged on the edge of the substrate.

[0021] Optionally, along the circumferential direction of the satellite dish, the edge of the satellite dish is provided with a plurality of the patterns, and the plurality of the patterns are the same or different.

[0022] Optionally, along the circumferential direction of the satellite dish, a linear distance between adjacent patterns is greater than the maximum range of the field of view.

[0023] Optionally, the MOCVD device further comprises a temperature acquisition module for collecting the temperature in the reaction chamber.

[0024] Optionally, the MOCVD device further includes a plurality of filters and a filter switching module; the filters are used to filter light of a corresponding wavelength range for the image acquisition device; and the filter switching module switches the corresponding filter for the image acquisition device according to the temperature in the reaction chamber.

[0025] Optionally, the image acquisition parameter adjustment module includes an exposure time adjustment module, which adjusts the exposure time of the image acquisition device based on the corresponding filter.

[0026] Optionally, the image acquisition parameter adjustment module further includes a frame rate adjustment module, which stores a plurality of calculation constants, including: a distance r2 between the mark and the center of the rotating unit, a radius r1 of the planetary disk, and the units of r1 and r2 are meters; an angular rotation velocity ω1 of the planetary disk, and a predicted angular rotation velocity ω2 of the rotating unit; ω2 is a multiple of ω1; the units of ω1 and ω2 are radians / second;

[0027] The frame rate adjustment module adjusts the frame rate f of the image acquisition device based on the multiple calculation constants and the size of the field of view;

[0028] The field of view is a rectangular field of view, L is the length of the short side of the field of view, in meters; v′ is the predicted ground motion speed of the marker, in meters per second, and t represents time;

[0029]

[0030] Optionally, the MOCVD equipment further includes: a plurality of flow regulating valves; the rotating unit is driven to rotate by airflow, and the plurality of flow regulating valves are respectively used to control the airflow provided to the plurality of rotating units; the controller adjusts the valve opening of the corresponding flow regulating valve based on the actual rotation angular velocity of the corresponding rotating unit.

[0031] Optionally, the image acquisition device acquires the image through an observation window on the side wall of the reaction chamber.

[0032] Optionally, the MOCVD device further includes a lighting module for improving the brightness within the field of view.

[0033] Optionally, the lighting module includes a light source and a light source adjustment device, which is used to switch the radiation parameters of the light source according to different temperatures in the reaction chamber and / or filters.

[0034] The present invention also provides a method for measuring the rotation speed of a satellite disk, which is implemented using the MOCVD device as described in the present invention, and comprises the steps of:

[0035] Setting working parameters of the image acquisition device;

[0036] During a first time period from when the mark enters the field of view of the image acquisition device to when it leaves the field of view, the image acquisition device acquires at least two marked images containing the mark;

[0037] The image processing module determines the rotating unit corresponding to the marked image and identifies the mark in the marked image; obtains the displacement of the mark based on two adjacent marked images, and calculates the actual rotation speed of the corresponding rotating unit based on the displacement.

[0038] Optionally, the method for measuring the rotation speed of the satellite disk further includes: measuring the rotation angle of the planetary disk relative to its initial position; and driving the image acquisition device to start or stop working based on the rotation angle.

[0039] Optionally, before driving the image acquisition device to start working, the method further includes: switching a corresponding filter for the image acquisition device based on the temperature in the reaction chamber.

[0040] Optionally, the setting of the working parameters of the image acquisition device includes: adjusting the exposure time of the image acquisition device based on the temperature in the reaction chamber and the switched filter, and / or

[0041] The frame rate of the image acquisition device is adjusted based on the predicted ground motion speed of the rotating unit and the size of the field of view.

[0042] Optionally, the image processing module determines the rotation unit corresponding to the marked image based on the rotation angle or the recognized mark.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1) The MOCVD equipment and satellite disk rotation speed measurement method of the present invention measures the actual rotation speed of the rotating unit through the collected marked image. The rotation speed data can be obtained during the process without delaying the process and can be measured in real time. According to the measurement results of the present invention, the air flow rate that drives the rotation of the rotating unit can be accurately adjusted, so that the actual rotation speed of the rotating unit meets the process requirements, ensuring that the surface temperature of the substrate reaches the temperature required by the process, and improving the yield rate of substrate processing.

[0045] 2) The present invention sets the frame rate of the image acquisition device based on the temperature in the reaction chamber, the field of view of the image acquisition device, the predicted ground motion speed of the marker, etc., to ensure that the image acquisition device can acquire at least two labeled images containing the same marker for measurement within the first time period from the marker entering the field of view of the image acquisition device to the marker leaving the field of view of the image acquisition device. Since the time interval between two adjacent image acquisitions within the first time period is very short, the two adjacent labeled images are selected for measurement, and the coupling effect of the rotation of the planetary disk on the rotation of the rotating unit can be ignored. Under the premise of ensuring the accuracy of the measurement results, the calculation complexity of the measurement results is greatly reduced.

[0046] 3) The filter switching module of the present invention can automatically switch the corresponding filter for the image acquisition device according to the temperature in the reaction chamber to filter the spectrum outside the set wavelength range, effectively improving the recognition rate of the image recognition unit to the mark and ensuring the accuracy of the measurement result. At the same time, the image acquisition parameter adjustment module also adjusts the exposure time of the image acquisition device based on the selected filter to improve the imaging quality.

[0047] 4) The mark in the present invention can be an existing notch on the edge of the substrate, or a pattern set on the edge of the satellite disk. Multiple patterns are set along the circumferential direction of the satellite disk to increase the probability of collecting marked images. In addition, the linear distance between adjacent patterns is greater than the maximum range of the field of view of the image acquisition device, so that two patterns will not enter the field of view at the same time, so that there is only one pattern in the collected marked image, which simplifies the recognition process of the mark in the image, avoids misjudgment of the mark, and further ensures the accuracy of the measurement result.

[0048] 5) The present invention drives the image acquisition device to start or stop working based on the rotation angle of the planetary disk relative to its initial position, thereby ensuring that the required marked images are acquired, while also reducing the acquisition times of the image acquisition device, avoiding the acquisition of a large number of invalid images, and effectively reducing the workload of the image recognition unit and the calculation unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the description. Obviously, the drawings described below are an embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0050] Figure 1 is a schematic diagram of a MOCVD device;

[0051] Figure 2 is a schematic diagram of a MOCVD device of the present invention;

[0052] Figure 3 is a top view of the rotating unit in the first embodiment;

[0053] Figure 4 This is a schematic diagram of an image acquisition device, a filter wheel, and an illumination module in Embodiment 1;

[0054] Figure 5 This is a schematic diagram of a plurality of filters arranged on a filter wheel in Embodiment 1;

[0055] Figure 6 Schematic diagram of the motion trajectory of the substrate notch and the substrate center in one embodiment;

[0056] Figure 7 This is a schematic diagram of the projection of the substrate on the upper surface of the planetary disk in Example 1;

[0057] Figure 8 This is a schematic diagram of the projection of the substrate on the upper surface of the planetary disk when the first and second labeled images are collected in Example 1;

[0058] Fig. 9 The schematic diagram of calculating the actual rotation speed of the rotating unit in the first embodiment;

[0059] Fig.10 is a top view of the rotating unit in the second embodiment;

[0060] Fig.11 This is a flow chart of the method for measuring the rotation speed of a satellite dish in the present invention. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0063] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0064] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0065] As used in this specification and the appended claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0066] In addition, in the description of the present application, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0067] Figure 1Schematic diagram of a MOCVD device 1, which includes a reaction chamber 10. The reaction chamber 10 includes a reaction chamber sidewall 100 and a chamber cover 102 which are roughly cylindrical. A planetary disk 104 (also called a base) in the reaction chamber is arranged on a rotatable shaft 107. Along the circumferential direction of the planetary disk 104, a plurality of recesses are provided on the upper surface of the planetary disk 104, and a plurality of satellite disks 105 for placing substrates W are respectively arranged in the plurality of recesses. A special airway (not shown in the figure) is provided in the recess, and an airflow is provided to the lower surface of the corresponding satellite disk 105 through the airway, so that the corresponding satellite disk 105 can be driven to rotate.

[0068] The planetary disk 104 and the satellite disk 105 are usually sintered from powdered materials (such as graphite) and have good thermal conductivity. A heating device 103 is provided below the planetary disk 104, and the planetary disk 104 transfers the heat radiated by the heating device 103 to the satellite disk 105 and the substrate W, so that the surface of the substrate reaches the temperature required by the process (usually greater than 1000°C).

[0069] The gas inlet device 101 is connected to a gas source 108 for supplying process gas, and the process gas is guided into the reaction chamber 10 through the gas inlet device 101. The process gas may include a carrier gas (carrier gas) and a reaction gas, and the reaction gas may include a Group III gas and a Group V gas. In a typical metal organic chemical vapor deposition process, the carrier gas may be nitrogen, hydrogen, or a mixture of nitrogen and hydrogen.

[0070] By driving the planetary disk 104 to rotate around its center, the satellite disk 105 is driven to rotate around the center of the planetary disk 104, and a certain pressure of gas is introduced between the satellite disk 105 and the planetary disk 104 through the gas channel along a certain direction set on the upper surface of the planetary disk 104, so that the satellite disk 105 can be lifted by the gas pressure and separated from the surface of the planetary disk 104, and then rotate around its center after being suspended at a certain height, so that different types of process gases reaching the upper surface of the substrate are deposited on the substrate in a uniform distribution. The process gas reacts and deposits on the substrate W at a specific temperature to form a thin film of the desired material, and the temperature of the substrate surface determines the rate of material deposition. An exhaust pump 106 is provided below the reaction chamber 10, and the process gas and reaction by-products that have not reacted in time are discharged from the reaction chamber 10 from the exhaust pump 106.

[0071] Since the airflow driving the satellite disk 105 to rotate has different flow paths in the planetary disk, and the air passage is prone to generate particles, etc., in order to ensure that the rotation speed of each satellite disk 105 is consistent, it is necessary to adjust the individual satellite disk 105. The rotation speed of the satellite disk 105 will affect the temperature of the substrate W, causing a large temperature difference between the substrates, and will also affect the uniformity of the thin film grown on the substrate surface. At present, there is no good way to measure the rotation speed of the satellite disk 105 in real time and accurately.

[0072] The present invention provides a method for measuring the rotation speed of a satellite disk and a MOCVD device. The notch at the edge of the substrate is used as a mark, or a mark is set on the edge of the satellite disk. The actual rotation speed of the satellite disk is measured according to the collected marked image. According to the speed measurement result of the present invention, the air flow rate driving the satellite disk to rotate can be accurately adjusted to ensure that the surface of the substrate reaches the temperature required by the process, thereby greatly improving the yield rate of substrate W processing.

[0073] Embodiment 1

[0074] The present invention provides a MOCVD device, such as Figure 2 As shown, it includes: a reaction chamber 20, an image acquisition device, an image acquisition parameter adjustment module 220, an image processing module 290, a position measurement device 230, a controller 240, a temperature acquisition module 250, a plurality of filters 262, a filter switching module 260, a plurality of flow regulating valves 270, and a lighting module 280.

[0075] A planetary disk 204 for carrying the substrate W is disposed in the reaction chamber 20. The planetary disk 204 is provided with a plurality of rotating units, such as Figure 3 As shown, the rotating unit includes a satellite disk 205 and a substrate W placed on the satellite disk 205. The edge of the substrate W has a notch for positioning during the film transmission process (the size of the notch in the figure is only for example). The planetary disk 204, the satellite disk 205, and the substrate W are all circular. During the processing of the substrate W, the planetary disk 204 drives the satellite disk 205 to rotate around the center of the planetary disk 204, and the satellite disk 205 also rotates around its own center of the circle, so that different types of process gases reaching the upper surface of the substrate are fully mixed. The rotation of the planetary disk 204 is usually driven by a motor, and the rotation speed of the planetary disk 204 can be accurately controlled by setting the working parameters of the motor. A plurality of air channels are provided in the planetary disk 204, which are connected to an external driving gas source 213 through a plurality of air inlet pipes 214. A driving gas (such as an inert gas) is provided to the lower surface of the plurality of satellite disks 205 through a plurality of air channels to drive the satellite disk 205 to rotate. In fact, the size of the airway is very small and is easily affected by the particles therein, which makes the stability of the driving gas flowing out of the airway inconsistent, resulting in unstable rotation speed of the satellite disk 205.

[0076] In this embodiment, the image acquisition device acquires the image of the rotating unit through the observation window 201 on the side wall of the reaction chamber. Figure 2 , Figure 4 As shown, the image acquisition device in this embodiment is a camera 210, which includes a body 2101 and a lens 2102. Figure 4 As shown, in this embodiment, the field of view 218 of the camera 210 is a rectangular field of view.

[0077] The camera 210 identifies the object based on the emissivity (i.e., the radiance) of the light signal radiated by the object. The wavelength of the light signal radiated by the object will change with the change of the ambient temperature. Generally, the higher the temperature, the shorter the wavelength of the light signal. The camera 210 has limited resolution for light signals that are not within the set wavelength range and cannot convert the light signal into a corresponding electrical signal, which interferes with the imaging of the camera 210 and ultimately results in the inability to identify the corresponding object in the image captured by the camera 210.

[0078] The temperature acquisition module 250 is used to collect temperature data in the reaction chamber. Figure 2 As shown, the bottom of the temperature acquisition module 250 in this embodiment passes through the chamber cover of the reaction chamber 20 and is located in the reaction chamber 20. Alternatively, the temperature acquisition module 250 can be hung on the inner wall of the reaction chamber 20 through a supporting device (such as a bracket, etc.). Figure 5 As shown, a plurality of filters 262 are arranged on the filter wheel 261. Figure 2 As shown, the lens 2102 is located between the filter wheel 261 and the body 2101. The filter switching module 260 is connected to the temperature acquisition module 250 and the filter wheel 261 by signal. The filter switching module 260 drives the filter wheel 261 to rotate according to the temperature data collected by the temperature acquisition module 250, so that the corresponding filter 262 is opposite to the lens 2102, so as to filter the light signal within the set wavelength range for the camera 210, thereby improving the recognition rate of objects in the image.

[0079] In this embodiment, the notch on the edge of the substrate is used as a mark of the rotating unit. The field of view 218 of the camera 210 at least covers a portion of the movement trajectory of the mark. Figure 6 It is shown in the figure that when the rotation speed of the planetary disk and the rotation speed of the satellite disk are 30 rpm (revolutions per minute) and 5 rpm respectively, the motion trajectory Gq of the substrate notch, the motion trajectory Gc of the substrate center, and the motion trajectory Gq of the part of the substrate notch that can be observed within the field of view range 218 (also called covered by the field of view range 218).

[0080] like Figure 2 As shown, the position measurement device 230 is used to measure the rotation angle α (in radians) of the planetary disk 204 relative to its initial position. Every time the planetary disk 204 rotates to its initial position, the MOCVD device generates a trigger synchronization signal and provides it to the position measurement device 230. (How to generate the trigger synchronization signal is a prior art and will not be described in detail here). In this embodiment, the position measurement device 230 also includes a timer, and each time the position measurement device 230 receives the trigger synchronization signal, the timer restarts the timing. When the time of the timer is T (in seconds), α=ω1T, ω1 (in radians / second) is the rotation angular velocity of the planetary disk 204.

[0081] The controller 240 signal connects the position measuring device 230 and the camera 210. Since the relative position relationship between the rotating unit and the planetary disk 204 remains unchanged, the controller 240 can determine whether each rotating unit enters or leaves the field of view 218 of the camera 210 according to the rotation angle α provided by the position measuring device 230. If it enters, the controller 240 drives the camera 210 to start working; if it leaves, the controller 240 drives the camera 210 to stop working. In this way, the workload of the image processing module 290 can be greatly reduced and a large amount of invalid acquisition can be avoided. It can also enable the camera 210 to start working before the mark enters the field of view 218, thereby improving the success rate of collecting marked images. In this embodiment, when each rotating unit enters the field of view 218, the camera 210 will be driven to work, so as to measure the actual rotation speed of each rotating unit according to the marked image of each rotating unit. In other embodiments, only the marked images of some rotating units can be collected, which is not limited in the present invention. In other embodiments, the camera 210 can also continue to collect images without judging whether the rotating unit enters the field of view.

[0082] The image acquisition parameter adjustment module 220 includes an exposure time adjustment module 2202 and a frame rate adjustment module 2201 .

[0083] When filtering the light signal, the filter 262 will inevitably affect the intensity of the light signal passing through the lens, thereby affecting the exposure time. In order to obtain clear images under different temperature conditions, the exposure time needs to be adjusted in some cases.

[0084] In this embodiment, a brightness acquisition module 21011 is also integrated in the fuselage 2101 for collecting brightness data within the field of view 218. In other embodiments, the brightness acquisition module 21011 may also be an independent module. The lighting module 280 is usually arranged outside the reaction chamber 20 to improve the brightness of the field of view 218. The exposure time adjustment module 2202 is connected to the filter switching module 260, the lighting module 280 and the brightness acquisition module 21011 by signal. While the filter switching module 260 drives the filter wheel 261 to rotate, it also sends a message to the exposure time adjustment module 2202, which includes the rotation angle of the filter wheel 261 relative to its initial position, or the number of the filter 262. Based on the received information and the brightness data within the field of view 218, the exposure time adjustment module 2202 drives the lighting module 280 to work and adjusts the exposure time of the camera 210. The lighting module 280 may include a light source and a light source adjustment device. When the process is executed, the temperature in the reaction chamber will change at different stages or with different process parameters. In order to accurately capture images under different conditions, the light source adjustment device will make appropriate adjustments to the ambient background light according to the temperature or the filter used. Specifically, it may include switching multiple light sources, such as one or more of a point light source, a coaxial light source, and a ring light source, or adjusting the wavelength, light intensity, or power of a single light source.

[0085] The frame rate adjustment module 2201 signal is connected to the camera 210 and is used to adjust the shooting frame rate of the camera 210 so that within the first time period from the mark entering the field of view 218 to leaving the field of view 218, the camera 210 can capture at least two marked images containing the same mark (a gap in this embodiment).

[0086] The frame rate adjustment module 2201 stores a plurality of calculation constants, including: the distance r2 between the mark and the rotation center of the rotating unit (in this embodiment, r2 is the radius of the substrate W), the radius r1 of the planetary disk 204, and the units of r1 and r2 are meters. The rotation angular velocity ω1 of the planetary disk 204, and the predicted rotation angular velocity ω2 of the rotating unit, and the units of ω1 and ω2 are radians / second. The predicted rotation angular velocity ω2 can also be understood as the ideal rotation angular velocity.

[0087] Figure 7 The small circle in represents the projection of the substrate W on the upper surface of the planetary disk. The first coordinate system is established with the plane where the upper surface of the planetary disk is located. When the planetary disk 204 is at the initial position, an edge point of one of the substrates W and the projection points a and b of the center of the substrate on the upper surface of the planetary disk all fall on the positive X-axis of the first coordinate system. A polar coordinate system is established with the projection point b as the pole, and the polar axis direction of the polar coordinate system points to the positive X-axis direction of the first coordinate system.

[0088] The planetary disk 204 is driven to rotate, and the satellite disk 205 is driven to rotate. After a time t, if Figure 7 As shown, in the first coordinate system, the coordinates of the projection point b are (x2, y2), and the predicted coordinates of the projection point a are (x, y). At this time, the predicted polar angle of the projection point a in the polar coordinate system is θ, θ = ω2t.

[0089] Easy to understand,

[0090] Derivatives of x and y with respect to t are obtained to obtain the predicted ground motion velocity V of the projection point a in the X and Y axis directions. x 、V y :

[0091] V x =-r1ω1sin(ω1t)-r2ω2sin(ω2t);

[0092] V y =r1ω1cos(ω1t)+r2ω2cos(ω2t).

[0093] Then the predicted ground motion speed v′ of the projection point a is:

[0094]

[0095] Obviously, the speed of the gap moving relative to the ground is also v′. is the length of the short side of the field of view 218. The length of the gap's moving trajectory in the field of view 218 is obviously greater than L, so the gap's moving time in the field of view 218 is greater than When the frame rate of the camera 210 is When the time interval between two consecutive image acquisitions of the camera 210 is less than If the camera 210 has started working before the gap enters the field of view 218 , the frame rate f can ensure that the camera 210 can capture at least two images containing the gap within the first time period from when the gap enters the field of view 218 to when it leaves the field of view 218 .

[0096] like Figure 2 As shown, the image processing module 290 includes an image recognition unit 2901 and a calculation unit 2902 .

[0097] The image recognition unit 2901 is communicatively connected to the camera 210 and the computing unit 2902. The image recognition unit 2901 receives the image captured by the camera 210, and recognizes the marked image from the received image, and recognizes the mark from the marked image. The image recognition unit 2901 can also convert the coordinates of the mark in the pixel coordinate system to the first coordinate system (this is the prior art and will not be described in detail here) and provide it to the computing unit 2902.

[0098] The image recognition unit 2901 and the calculation unit 2902 are also communicatively connected to the controller 240. The image recognition unit 2901 determines the rotation unit corresponding to the marked image according to the rotation angle α provided by the controller 240, and provides the determination result to the controller 240.

[0099] The calculation unit 2902 obtains the displacement of the corresponding mark based on the coordinates of the same mark (in this embodiment, the notch on the edge of the substrate) in two adjacent marked images (recorded as the first marked image and the second marked image, respectively) captured twice within the first time period in the first coordinate system; and based on the displacement and the time interval between two adjacent shots, calculates the actual rotation speed of the corresponding rotating unit and provides it to the controller 240.

[0100] t1 and t2 are the acquisition time of the first labeled image and the second labeled image respectively, in seconds. <t2。 Figure 8 The two small circles represent the projection of substrate W on the surface of the planetary disk at time t1 and t2 respectively. Figure 8 As shown, at time t1, the notch at the edge of the substrate has a first projection point c on the upper surface of the planetary disk, and the center of the substrate has a third projection point o on the upper surface of the planetary disk. At time t2, the notch at the edge of the substrate has a second projection point d on the upper surface of the planetary disk, and the center of the substrate has a fourth projection point o' on the upper surface of the planetary disk. Since the time interval between t1 and t2 is very short, we can ignore the coupling effect of the rotation of the planetary disk 204 on the rotation of the rotating unit. Fig. 9 As shown, the third projection point o and the fourth projection point o' are considered to coincide, and ∠A is obtained. ∠A (in radians) takes the third projection point o as the vertex angle, and the first projection point c and the second projection point d fall on the two rays of ∠A respectively.

[0101] The image recognition unit 2901 can obtain the coordinates of the third projection point o in the first coordinate system according to the rotation angle α. By converting the coordinates of the gap in the first marked image and the gap in the second marked image in the pixel coordinate system to the first coordinate system through the image recognition unit 2901, the coordinates of the first projection point c and the second projection point d in the first coordinate system can be obtained.

[0102] The calculation unit 2902 calculates the radian value corresponding to ∠A according to the coordinates of the first projection point c, the second projection point d, and the third projection point in the first coordinate system. Then, the radian value corresponding to ∠A is used as the displacement of the gap from time t1 to t2 to calculate the actual rotation angular velocity of the rotating unit from time t1 to t2. Actual rotation speed

[0103] Obviously, by selecting the first labeled image and the second labeled image for measurement, the calculation complexity of the measurement result is greatly reduced while ensuring the accuracy of the measurement result.

[0104] In another embodiment, the computing unit 2902 will Fig. 9 The straight-line distance l (in meters) between the first projection point c and the second projection point d is used as the displacement of the gap, and the linear velocity of the gap from time t1 to t2 is calculated. The linear velocity is then converted into the actual rotation speed of the substrate W. Compared with the above method, the accuracy of this method is slightly lower.

[0105] like Figure 2 As shown, a plurality of flow regulating valves 270 are respectively arranged on a plurality of air inlet pipes 214 and are respectively connected to the controller 240 by signals. The controller 240 generates a corresponding flow regulating signal based on the actual rotation angular velocity of the corresponding rotating unit to adjust the valve opening of the corresponding flow regulating valve 270, and finally adjusts the air flow rate driving the rotating unit to rotate, so that the actual rotation speed of the rotating unit meets the process requirements, ensures that the surface temperature of the substrate reaches the temperature required by the process, and improves the yield rate of the substrate W processing.

[0106] The image acquisition parameter adjustment module 220, the position measurement device 230, the controller 240, the filter switching module 260, and the image processing module 290 can be independent electronic devices, which are connected via data transmission lines; or the above modules can also be integrated into a circuit board, which is not limited in the present invention.

[0107] Embodiment 2

[0108] like Fig.10 As shown, in this embodiment, multiple patterns are provided on the edge of the satellite dish 205 along the circumferential direction of the satellite dish 205. The multiple patterns serve as multiple marks of the rotating unit, which greatly increases the success rate of collecting marked images. In other embodiments, the number of patterns can also be only one, which is not limited in the present invention. In this embodiment, as shown in FIG. Fig.10 As shown, the edge of the satellite dish 205 is provided with a plurality of identical diamond patterns. In other embodiments, the pattern may also be other geometric shapes (such as any one or more of a triangle, a square, and a circle), or stripes, a combination of stripes and dots, etc. may be used as the pattern, which is not limited in the present invention. For example, in the field of view 218, there are stripes composed of three lines with unequal spacing, and multiple stripes of this type may be arranged uniformly or unevenly along the circumference.

[0109] In this embodiment, the linear distance between adjacent patterns is greater than the maximum range of the field of view (the diagonal length of the field of view range 218), so that only one pattern is present in the captured labeled image. In other words, no two marks will appear in the same labeled image at the same time. The image recognition unit does not need to recognize the same mark from the first labeled image and the second labeled image, which can avoid misjudgment of the mark and further ensure the accuracy of the measurement result.

[0110] In another embodiment, the multiple patterns on the same satellite dish 205 are different from each other. When at least two of the multiple patterns simultaneously enter the field of view 218, it is convenient for the image recognition unit to determine the same mark in the first marked image and the second marked image. When the image recognition unit 2901 provides the coordinates of the mark in the first coordinate system to the calculation unit 2902, it also provides the mark number of the mark, so that the calculation unit 2902 can select the coordinates of the same mark for calculation.

[0111] In another embodiment, the patterns of different satellite dishes 205 may also be different from each other, and the image recognition unit may determine the rotation unit corresponding to the marked image based on the recognized pattern.

[0112] The present invention also provides a method for measuring the rotation speed of a satellite disk, which is implemented by using the MOCVD device of the present invention. Fig.11 As shown, it includes the steps:

[0113] S1. Setting working parameters of the image acquisition device.

[0114] Setting the working parameters of the image acquisition device includes: adjusting the exposure time of the image acquisition device based on the temperature in the reaction chamber and the switched filter, and / or adjusting the frame rate of the image acquisition device based on the predicted ground motion speed of the rotating unit and the size of the field of view.

[0115] In one embodiment, step S1 further includes switching a corresponding filter for the image acquisition device based on the temperature in the reaction chamber.

[0116] S2. Within a first time period from when the mark enters the field of view of the image acquisition device to when it leaves the field of view, the image acquisition device acquires at least two marked images containing the mark.

[0117] Obviously, the image acquisition device can be kept working while the planetary disk is rotating, but this will collect a large number of invalid images without marks. In one embodiment, in order to reduce the number of images collected without marks, step S2 also includes: measuring the rotation angle of the planetary disk relative to its initial position, and driving the image acquisition device to start or stop working based on the rotation angle.

[0118] S3, the image processing module determines the rotating unit corresponding to the marked image, and identifies the mark in the marked image; based on two adjacent marked images collected, obtains the displacement of the mark, and calculates the actual rotation speed of the corresponding rotating unit based on the displacement.

[0119] The image processing module determines the rotation unit corresponding to the marked image based on the rotation angle or the recognized mark.

[0120] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0121] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A MOCVD device, comprising a reaction chamber, wherein a planetary disk for carrying a substrate is provided in the reaction chamber, wherein: A plurality of rotating units are provided on the planetary disk, and at least one mark is provided on the edge of the rotating unit; The MOCVD device further includes: An image acquisition device for acquiring an image of the rotating unit; the field of view range of the image acquisition device covers at least a partial movement trajectory of the mark; An image acquisition parameter adjustment module for adjusting the operating parameters of the image acquisition device; An image processing module configured to calculate the actual rotation speed of the corresponding rotating unit based on the acquired marked image; the marked image is the image including the mark.

2. The MOCVD device according to claim 1, characterized in that: Within a first time period from when the mark enters the field of view range to when it leaves the field of view range, the image acquisition device can acquire at least two marked images including the same mark.

3. The MOCVD device according to claim 2, characterized in that: The image processing module includes: an image recognition unit and a calculation unit; The image recognition unit is configured to recognize the marked image from the acquired image and recognize the mark from the marked image; The calculation unit is configured to: obtain the displacement of the corresponding mark based on two adjacent acquired marked images including the same mark within the first time period; And calculate the actual rotation speed of the corresponding rotating unit based on the displacement and the time interval between the two adjacent shootings.

4. The MOCVD device according to claim 3, characterized in that The two marked images including the same mark are respectively a first marked image and a second marked image; t1 and t2 are respectively the acquisition times of the first marked image and the second marked image, with the unit of second; t1 < t2; at times t1 and t2, the same mark has a first projection point and a second projection point on the upper surface of the planetary disk respectively; at time t1, the center of the rotating unit corresponding to the first marked image has a third projection point on the upper surface of the planetary disk; ∠A has the third projection point as the apex angle, and the first projection point and the second projection point respectively fall on two rays of ∠A, and the unit of ∠A is radian; the actual rotation speed of the rotating unit corresponding to the first marked image within the time period from t1 to t2 is v, with the unit of revolutions per minute.

5. The MOCVD device according to claim 1, characterized in that: It further includes a position measurement device and a controller; the position measurement device is used to measure the rotation angle of the planetary disk relative to its initial position; the controller drives the image acquisition device to start or stop working based on the rotation angle.

6. The MOCVD device according to claim 5, characterized in that: The image processing module determines the rotating unit corresponding to the marked image based on the rotation angle.

7. The MOCVD device according to claim 1, characterized in that: Different rotating units have different marks; the image processing module determines the rotating unit corresponding to the marked image based on the recognized mark.

8. The MOCVD device according to claim 1, characterized in that: The rotating unit includes a satellite disk and a substrate placed on the satellite disk; the mark includes a pattern provided on the edge of the satellite disk and / or a notch provided on the edge of the substrate.

9. The MOCVD device according to claim 8, characterized in that Along the circumferential direction of the satellite disk, a plurality of the patterns are provided on the edge of the satellite disk, and the plurality of patterns are the same or different.

10. The MOCVD device according to claim 9, characterized in that: Along the circumferential direction of the satellite disk, the linear distance between adjacent patterns is greater than the maximum range of the field of view.

11. The MOCVD device according to claim 1, characterized in that: It further includes a temperature acquisition module for acquiring the temperature in the reaction chamber.

12. The MOCVD device according to claim 11, characterized in that It also includes a plurality of filters and a filter switching module; the filters are used to filter the light of the corresponding wavelength range for the image acquisition device; and the filter switching module switches the corresponding filter for the image acquisition device according to the temperature in the reaction chamber.

13. The MOCVD device according to claim 12, characterized in that: The image acquisition parameter adjustment module includes an exposure time adjustment module, which adjusts the exposure time of the image acquisition device based on the corresponding filter.

14. The MOCVD device according to claim 1, wherein: The image acquisition parameter adjustment module further includes a frame rate adjustment module; the frame rate adjustment module stores a plurality of calculation constants, including: the distance r2 between the mark and the center of the rotating unit, the radius r1 of the planetary disk, the units of r1 and r2 are meters; the rotation angular velocity ω1 of the planetary disk, the predicted rotation angular velocity ω2 of the rotating unit; ω2 is a multiple of ω1; the units of ω1 and ω2 are radians / second; The frame rate adjustment module adjusts the frame rate f of the image acquisition device based on the multiple calculation constants and the size of the field of view; The field of view is a rectangular field of view, L is the length of the short side of the field of view, in meters; v ′ is the predicted ground velocity of the marker, in meters per second, and t represents time; 15. The MOCVD device according to claim 5, characterized in that: It also includes: multiple flow regulating valves; the rotating unit is driven to rotate by airflow, and the multiple flow regulating valves are respectively used to control the airflow provided to the multiple rotating units; the controller adjusts the valve opening of the corresponding flow regulating valve based on the actual rotation angular velocity of the corresponding rotating unit.

16. The MOCVD device according to claim 1, wherein: The image acquisition device acquires the image through an observation window on the side wall of the reaction chamber.

17. The MOCVD device according to claim 1, wherein: It also includes a lighting module for improving the brightness within the field of view.

18. The MOCVD device according to claim 17, characterized in that The lighting module comprises a light source and a light source adjustment device, which is used to switch the radiation parameters of the light source according to different temperatures in the reaction chamber and / or filters.

19. A method for measuring the rotation speed of a satellite disk, implemented by using the MOCVD device according to any one of claims 1 to 18, characterized in that: Contains steps: Setting working parameters of the image acquisition device; During a first time period from when the mark enters the field of view of the image acquisition device to when it leaves the field of view, the image acquisition device acquires at least two marked images containing the mark; The image processing module determines the rotating unit corresponding to the marked image and identifies the mark in the marked image; obtains the displacement of the mark based on two adjacent marked images, and calculates the actual rotation speed of the corresponding rotating unit based on the displacement.

20. The method for measuring the rotation speed of a satellite dish according to claim 19, characterized in that: The method also includes: measuring the rotation angle of the planetary disk relative to its initial position; and driving the image acquisition device to start or stop working based on the rotation angle.

21. The method for measuring the rotation speed of a satellite dish according to claim 20, characterized in that: Before driving the image acquisition device to start working, the method further includes: switching a corresponding filter for the image acquisition device based on the temperature in the reaction chamber.

22. The method for measuring the rotation speed of a satellite dish according to claim 21, characterized in that: The setting of the working parameters of the image acquisition device includes: adjusting the exposure time of the image acquisition device based on the temperature in the reaction chamber and the switched filter, and / or The frame rate of the image acquisition device is adjusted based on the predicted ground motion speed of the rotating unit and the size of the field of view.

23. The method for measuring the rotation speed of a satellite dish according to claim 20, characterized in that: The image processing module determines the rotation unit corresponding to the marked image based on the rotation angle or the recognized mark.

Images