Magnetron and magnetron sputtering device

Abstract

The magnetron comprises a load base, a magnetic pole array and an adjusting component, the magnetic pole array comprises a plurality of magnetic pole units evenly distributed on the supporting surface of the load base, and each magnetic pole unit comprises at least one first magnetic pole and at least one second magnetic pole; the polarities of the first magnetic pole and the second magnetic pole are opposite; the adjusting parts are located on the load base, each first magnetic pole and each second magnetic pole are provided with the adjusting parts, and the adjusting parts are used for adjusting the positions of the first magnetic poles and / or the second magnetic poles in the axial direction. According to the magnetron and the magnetron sputtering device, accurate control over the magnetic field intensity is achieved, the stability of the working frequency of the magnetron can be kept, and the sputtering rate of the magnetron sputtering device and the uniformity of thin film deposition are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, in particular to a magnetron and a magnetron sputtering device. BACKGROUND

[0002] The magnetron is a key component in the magnetron sputtering process. Its main function is to form a high-density plasma near the target surface through the joint action of magnetic field and electric field, thereby improving the sputtering efficiency and film quality. However, the traditional magnetron design has some limitations, especially in terms of magnetic field distribution uniformity and target utilization rate.

[0003] The magnetic field of the magnetron is generated by permanent magnets. Due to the closed nature and natural unevenness of magnetic lines, the electron density in each region of the target surface is uneven. This not only affects the uniform erosion of the target, but also leads to the unevenness of the film.

[0004] In order to improve the uniformity of the magnetic field distribution and the utilization rate of the target, researchers have developed various shaped magnetron designs, such as D-shaped and heart-shaped magnetrons. Figure 1 and Figure 2 As shown in the structure diagram of the magnetic embryo inside the D-shaped magnetron in the prior art and the structure diagram of the magnetic pole inside, including magnetic embryo 01, inner magnetic pole 02, outer magnetic pole 03 and counterweight 04. Among them, the D-shaped magnetron optimizes the magnetic field distribution, so that the magnetic field forms a better coverage in the radial region of the target, thereby improving the uniform erosion of the target and the uniformity of the film. The heart-shaped magnetron further optimizes the magnetic field distribution through special magnetic field design, but the uniformity of the magnetic field of this design is difficult to adjust and control. However, the D-shaped magnetron can only be adjusted radially and cannot be adjusted axially. This design limits the optimization space of the magnetic field, resulting in a low utilization rate of the target. And the D-shaped magnetron needs to adjust the counterweight synchronously when adjusting radially, which is easy to cause imbalance and centrifugal phenomenon. And the heart-shaped and other shaped designs cannot be adjusted. CONTENT OF THE UTILITY MODEL

[0005] Therefore, it is necessary to provide a magnetron and a magnetron sputtering device to solve the problem of difficulty in adjusting and controlling the uniformity of the magnetic field distribution in the prior art magnetron.

[0006] In order to achieve the above purpose, the present application provides a magnetron, comprising:

[0007] a load base;

[0008] a magnetic pole array comprising a plurality of magnetic pole units uniformly arranged on the support surface of the load base, the magnetic pole unit comprising at least one first magnetic pole and at least one second magnetic pole, the polarity of the first magnetic pole and the second magnetic pole being opposite;

[0009] An adjusting component is arranged on the load base, and each of the first magnetic pole and the second magnetic pole is provided with the adjusting component, and the adjusting component is used for adjusting the position of the first magnetic pole and / or the second magnetic pole in the axial direction.

[0010] In one of the embodiments, the adjusting component comprises an adjusting screw, and the position of the first magnetic pole and / or the second magnetic pole in the axial direction is adjusted by tightening or loosening the adjusting screw.

[0011] In one of the embodiments, the adjusting component further comprises an adjusting washer, and the position of the first magnetic pole and / or the second magnetic pole in the axial direction is adjusted by arranging different numbers of the adjusting washers on the adjusting screw.

[0012] In one of the embodiments, the first magnetic pole and the second magnetic pole are fixed to the load base through a fixing frame, and the fixing frame is fixed to the load base through the adjusting screw.

[0013] In one of the embodiments, the adjusting component is arranged on opposite sides of the first magnetic pole and the second magnetic pole, respectively.

[0014] In one of the embodiments, the magnetron further comprises a support portion, a cover portion and a fixing bolt, the support portion is arranged between the load base and the cover portion, and the cover portion and the support portion are fixed to the support portion through the fixing bolt.

[0015] In one of the embodiments, the magnetic pole units are arranged in a ring shape on the load base, and the support portion is further arranged between each of the magnetic pole units arranged in a ring shape.

[0016] In one of the embodiments, the magnetic pole unit comprises one first magnetic pole and two second magnetic poles arranged on opposite sides of the first magnetic pole, respectively; or the magnetic pole unit comprises one second magnetic pole and two first magnetic poles arranged on opposite sides of the second magnetic pole, respectively.

[0017] In one of the embodiments, the magnetron further comprises a driving portion, and the driving portion is arranged on the axial center line of the magnetron.

[0018] The application further provides a magnetron sputtering device, which comprises the magnetron as described in any one of the above embodiments.

[0019] The magnetron in the embodiments of the present application improves the uniformity of the magnetic field, reduces the fluctuation of the magnetic field strength, and ensures the working stability of the magnetron by arranging the magnetic pole array to include a plurality of magnetic pole units arranged uniformly on the support surface of the load base. In addition, by arranging the magnetic pole array to include a plurality of magnetic pole units arranged uniformly on the support surface of the load base, and arranging the adjusting component to adjust the position of the first magnetic pole and / or the second magnetic pole in the axial direction, the relative position between the magnetic poles in the radial and axial directions can be adjusted, thereby changing the distribution and strength of the magnetic field. Compared with the traditional magnetic pole adjustment method, this adjustment method is more flexible, can accurately control the magnetic field strength without changing the overall structure of the magnetic pole array, helps to maintain the stability of the working frequency of the magnetron, can meet different design requirements, improves the adaptability and versatility of the equipment, and applies the above-mentioned magnetron to the magnetron sputtering device to improve the sputtering rate of the magnetron sputtering device and the uniformity of thin film deposition. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 A structural schematic diagram of an internal magnetic core of a magnetron provided in the prior art;

[0022] Figure 2 A schematic diagram of the arrangement structure of the magnetic poles inside a magnetron provided in the prior art;

[0023] Figure 3 A structural schematic diagram of a magnetron provided in an embodiment;

[0024] Figure 4 A structural schematic diagram of a fixed frame and an adjusting component of a magnetron provided in an embodiment;

[0025] Figure 5 A schematic diagram of one arrangement structure of the magnetic pole units of a magnetron provided in an embodiment;

[0026] Figure 6 A schematic diagram of another arrangement structure of the magnetic pole units of a magnetron provided in an embodiment;

[0027] Figure 7 A schematic diagram of a third arrangement structure of the magnetic pole units of a magnetron provided in an embodiment;

[0028] Figure 8A structure diagram of a magnetron provided in an embodiment, in which a first magnetic pole and a second magnetic pole are in an initial position;

[0029] Figure 9 A structure diagram of a magnetron provided in an embodiment, in which a second magnetic pole is provided with an adjusting spacer.

[0030] BRIEF DESCRIPTION OF DRAWINGS

[0031] 01 - magnetic embryo, 02 - inner magnetic pole, 03 - outer magnetic pole, 04 - counterweight, 1 - load base, 2 - magnetic pole array, 21 - magnetic pole unit, 211 - first magnetic pole, 212 - second magnetic pole, 3 - adjusting part, 31 - adjusting screw, 32 - adjusting spacer, 4 - support part, 5 - cover part, 6 - fixing bolt, 7 - driving part, 8 - fixing frame. DETAILED DESCRIPTION

[0032] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present application is more thorough and complete.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein only for the purpose of describing specific embodiments of the present application, and is not intended to limit the present application.

[0034] In the description of the present application, it should be understood that if these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0035] In addition, the terms "first", "second", and the like, if any, are used herein for descriptive purposes only and should not be construed as indicating or implying relative importance or implicating the number of indicated technical features. Thus, a feature defined with "first" or "second" can include at least one of the features explicitly or implicitly. In the description of the present application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0036] In the present application, unless otherwise explicitly specified and limited, if the terms "mounting", "connecting", "connecting", "fixing" and the like appear, these terms should be interpreted broadly. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0037] In the present application, unless otherwise explicitly specified and limited, if the first feature is described as "on" or "under" the second feature, etc., it can mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be the first feature directly above or obliquely above the second feature, or only indicate that the first feature is higher than the second feature in horizontal height. The first feature "below", "below" and "below" the second feature can be the first feature directly below or obliquely below the second feature, or only indicate that the first feature is lower than the second feature in horizontal height.

[0038] It should be noted that if an element is referred to as "fixed to" or "disposed on" another element, it can be directly on another element or there can be a middle element. If an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are only for illustrative purposes and do not represent the only implementation.

[0039] See Figure 3 and Figure 4The embodiment of the present application provides a magnetron, which comprises a load base 1, a magnetic pole array 2 and an adjusting component 3, wherein the magnetic pole array 2 comprises a plurality of magnetic pole units 21 which are uniformly arranged on a supporting surface of the load base 1, the magnetic pole unit 21 comprises at least one first magnetic pole 211 and at least one second magnetic pole 212, and the polarities of the first magnetic pole 211 and the second magnetic pole 212 are opposite; the adjusting component 3 is arranged on the load base 1, and each first magnetic pole 211 and each second magnetic pole 212 is provided with the adjusting component 3, and the adjusting component 3 is used for adjusting the position of the first magnetic pole 211 and / or the second magnetic pole 212 in the axial direction.

[0040] The magnetron improves the uniformity of the magnetic field, reduces the fluctuation of the magnetic field intensity, and guarantees the working stability of the magnetron by arranging the magnetic pole array 2 to comprise a plurality of magnetic pole units 21 which are uniformly arranged on the supporting surface of the load base 1. In addition, the plurality of magnetic pole units 21 which are uniformly arranged on the supporting surface of the load base 1 and the adjusting component 3 arranged to adjust the position of the first magnetic pole 211 and / or the second magnetic pole 212 in the axial direction can realize the adjustment of the relative position between the magnetic poles in the radial direction and the axial direction, so as to change the distribution and intensity of the magnetic field. Compared with the traditional magnetic pole adjustment method, the adjustment method is more flexible, can realize the accurate control of the magnetic field intensity without changing the overall structure of the magnetic pole array 2, helps to maintain the stability of the working frequency of the magnetron, can meet different design requirements, and improves the adaptability and universality of the equipment.

[0041] In some embodiments, the load base 1 is used for providing mechanical support for the magnetic pole array 2, so as to guarantee the stability and reliability of the magnetic pole array 2 in the rotating process. The material of the load base 1 comprises non-high-permeability metal materials such as non-iron, cobalt, nickel, permalloy and the like. The non-high-permeability metal materials can effectively avoid the interference and loss of the magnetic force lines by using the characteristic of not being magnetically conductive, prevent magnetic short circuit, ensure the uniformity and stability of the magnetic field, make the magnetic force lines pass through the load base 1, and then effectively act on the target material, and guarantee the performance of the magnetic pole array 2. The shape of the load base 1 comprises a circular shape, which is beneficial to control the rotation of the magnetron, achieve the uniformity of the overall magnetic induction intensity, and realize higher sputtering rate and film deposition uniformity.

[0042] In some embodiments, please refer to Figure 3, the magnetron further comprises a support part 4, a cover part 5 and a fixing bolt 6. The support part 4 is located between the load base 1 and the cover part 5, and the cover part 5 is fixed to the load base 1 by the fixing bolt 6. The magnetic pole array 2 is located in the space enclosed by the load base 1, the support part 4 and the cover part 5. The main function of the support part 4 is to provide additional mechanical support and ensure the stability of the magnetic pole array 2 and other components. In addition, the support part 4 can also be used to adjust the position of the magnetic pole array 2. The cover part 5 is used to protect the internal components from external interference. The fixing bolt 6 passes through the cover part 5 and the load base 1 to fix the cover part 5 to the load base 1, ensuring the structural stability of the entire magnetron. The support part 4 and the cover part 5 are made of non-high permeability metal materials such as non-iron, cobalt, nickel, and permalloy, which can ensure the uniformity and stability of the magnetic field by taking advantage of their own non-magnetic properties, allowing the magnetic field lines to pass through and effectively act on the target material.

[0043] In some embodiments, referring to Figure 3 , the magnetron further comprises a drive part 7 located on the axial center line of the magnetron body. The drive part 7 comprises a motor coupling for connecting with a motor and being driven to rotate by the motor. By connecting the drive part 7, i.e. the motor coupling, with an external motor, power is provided by the motor to drive the magnetic pole array 2 or other related components inside the magnetron to rotate, which can make the magnetic field distribution more uniform. This rotation can reduce the local non-uniformity of the magnetic field, thereby improving the overall performance of the magnetron and achieving higher sputtering rate and film deposition uniformity.

[0044] For example, the magnetic pole array 2 is located in the space enclosed by the load base 1, the support part 4 and the cover part 5, and is uniformly distributed on the support surface of the load base 1, which can ensure the uniformity and symmetry of the magnetic field.

[0045] In some embodiments, referring to Figure 5 , the magnetic pole units 21 are arranged in a ring shape on the load base 1, and the support part 4 is also located between each ring-shaped arrangement of magnetic pole units 21. The ring-shaped uniform distribution arrangement can ensure the uniform distribution of the magnetic field in the radial direction. The support part 4 not only locates between the load base 1 and the cover part 5, but also between each ring-shaped arrangement of magnetic pole units 21, which can provide additional mechanical support and adjust the arrangement position of the magnetic pole units 21 to ensure the stability and position accuracy of the magnetic pole units 21.

[0046] In other embodiments, referring to Figure 6 , the magnetic pole units 21 are arranged along multiple parallel chord lines on the support surface of the load base 1. This makes the magnetic field more uniform on the support surface and reduces the fluctuation of local magnetic field strength. This uniform magnetic field distribution helps to improve the performance of the magnetron.

[0047] In other embodiments, referring toFigure 7 The magnetic pole units 21 are arranged along multiple radial directions on the support surface of the load base 1. By arranging the magnetic pole units 21 evenly along the radial directions, the fluctuation of the local magnetic field strength can be reduced, and the magnetic field distribution can be more uniform.

[0048] Exemplarily, by adjusting the arrangement of the magnetic pole units 21 on the load base 1, the strength and radial distribution of the magnetic field can be flexibly controlled to adapt to different working modes.

[0049] Exemplarily, each magnetic pole unit 21 includes at least one first magnetic pole 211 and at least one second magnetic pole 212, and the first magnetic pole 211 and the second magnetic pole 212 have opposite polarities. The first magnetic pole 211 and the second magnetic pole 212 respectively represent one of N-pole and S-pole. When the first magnetic pole 211 is N-pole, the second magnetic pole 212 is S-pole. When the first magnetic pole 211 is S-pole, the second magnetic pole 212 is N-pole. This alternating polarity design can enhance the strength and uniformity of the magnetic field.

[0050] In some embodiments, the magnetic pole unit 21 includes one first magnetic pole 211 and one second magnetic pole 212 located on opposite sides of the first magnetic pole 211; or the magnetic pole unit 21 includes one second magnetic pole 212 and one first magnetic pole 211 located on opposite sides of the second magnetic pole 212. That is, by designing different numbers of magnetic pole pairs in the magnetic pole unit 21, the sputtering rate required by the target material of different materials can be matched. For example, when the sputtering rate requirement is not high, the arrangement of the magnetic poles in the magnetic pole unit 21 can be one first magnetic pole 211 and one second magnetic pole 212. When a higher sputtering rate is required, the magnetic pole unit 21 includes one first magnetic pole 211 and one second magnetic pole 212 located on opposite sides of the first magnetic pole 211; or the magnetic pole unit 21 includes one second magnetic pole 212 and one first magnetic pole 211 located on opposite sides of the second magnetic pole 212, so as to increase one set of magnetic lines of force and improve the overall magnetic induction strength, so as to improve the plasma density of the magnetron sputtering device, and thus improve the sputtering rate.

[0051] In some embodiments, the first magnetic pole 211 and the second magnetic pole 212 are fixed to the load base 1 by the fixed frame 8, and the fixed frame 8 is fixed to the load base 1 by the adjusting screw 31. The fixed frame 8 is used to fix the first magnetic pole 211 and the second magnetic pole 212 on the load base 1, and provides sufficient mechanical strength to ensure that the magnetic pole unit 21 will not be displaced due to vibration or external force during operation, thereby ensuring the stability of the magnetic pole unit 21.

[0052] Exemplarily, by setting the adjusting component 3 to adjust the positions of the first magnetic pole 211 and the second magnetic pole 212 in the axial direction, the precise regulation of the magnetic field can be achieved, the distribution of the magnetic field can be optimized, the local fluctuation of the magnetic field can be reduced, and the stability and uniformity of the magnetic field can be improved. The axial position adjustability of the magnetic poles is provided, so that the device can be dynamically adjusted as needed during operation, increasing flexibility.

[0053] In some embodiments, referring to Figure 4 , Figure 8 and Figure 9 , the adjusting component 3 includes an adjusting screw 31, by tightening or loosening the adjusting screw 31, the positions of the first magnetic pole 211 and / or the second magnetic pole 212 in the axial direction are adjusted. The adjusting component 3 also includes an adjusting washer 32, by setting different numbers of adjusting washers 32 on the adjusting screw 31, the positions of the first magnetic pole 211 and / or the second magnetic pole 212 in the axial direction are adjusted. The adjusting screw 31 is used to fix the fixed frame 8 on the load base 1, ensuring the stability of the magnetic pole unit 21, and by tightening or loosening the adjusting screw 31 and setting different numbers of adjusting washers 32 on the adjusting screw 31, the position of the fixed frame 8 in the axial direction can be changed, thereby adjusting the positions of the first magnetic pole 211 and / or the second magnetic pole 212 in the axial direction.

[0054] By setting the adjusting washer 32 and by increasing or decreasing the number of adjusting washers 32 on the adjusting screw 31, the number and thickness of the adjusting washers 32 can be further adjusted as needed to achieve the desired magnetic field distribution. And the adjusting washer 32 can also act as a buffer, reducing the impact of mechanical vibration on the magnetic field distribution, avoiding the phenomenon of adjusting screw 31 slipping during long-term rotation of the magnetron, and improving the stability of the magnetron.

[0055] In some embodiments, the adjusting component 3 is located on the opposite sides of the first magnetic pole 211 and the second magnetic pole 212 respectively. This layout can provide more uniform adjusting force, ensuring that the position adjustment of the magnetic poles in the axial direction is more stable and accurate. And this layout has symmetry, which can reduce the fluctuation of the magnetic field caused by uneven adjusting force, and improve the uniformity and stability of the magnetic field.

[0056] In some embodiments, the application also provides a magnetron sputtering device, which includes the magnetron as described above.

[0057] Exemplarily, a target material is further arranged in the magnetron sputtering device, and a magnetron is arranged on the target material. The magnetron captures electrons by generating a magnetic field near the surface of the target material, and the electrons move along a spiral track under the action of the magnetic field, thereby increasing the electron density near the surface of the target material, forming a high-density plasma, and thus improving the sputtering efficiency. Moreover, the magnetic field can also precisely control the deposition rate and thickness by manipulating the path of sputtered atoms. That is, the application of the magnetron in the magnetron sputtering device improves the utilization rate of the target material, reduces the production cost, and improves the uniformity of the film layer.

[0058] In the description of the present specification, the description referring to the terms "some embodiments", "other embodiments", "ideal embodiments", and the like means that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example.

[0059] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, all possible combinations of the technical features of the above-described embodiments are not described, however, as long as the combinations of the technical features do not contradict each other, they should be considered as falling within the scope of the present specification.

[0060] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent application scope. It should be noted that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A magnetron, characterized by, The magnetron comprises: a load base; a magnetic pole array comprising a plurality of magnetic pole units arranged uniformly on a support surface of the load base, each of the magnetic pole units comprising at least one first magnetic pole and at least one second magnetic pole, the first magnetic pole and the second magnetic pole having opposite polarities; an adjusting component arranged on the load base, each of the first magnetic poles and each of the second magnetic poles being provided with the adjusting component, the adjusting component being used for adjusting a position of the first magnetic pole and / or the second magnetic pole in an axial direction.

2. The magnetron of claim 1, wherein The adjusting component comprises an adjusting screw, the position of the first magnetic pole and / or the second magnetic pole in the axial direction being adjusted by tightening or loosening the adjusting screw.

3. The magnetron of claim 2, wherein The adjusting component further comprises an adjusting washer, the position of the first magnetic pole and / or the second magnetic pole in the axial direction being adjusted by arranging different numbers of the adjusting washers on the adjusting screw.

4. The magnetron of claim 2, wherein The first magnetic poles and the second magnetic poles are fixed to the load base by a fixing frame, the fixing frame being fixed to the load base by the adjusting screw.

5. The magnetron of claim 1, wherein The adjusting component is arranged on opposite sides of the first magnetic poles and the second magnetic poles, respectively.

6. The magnetron of claim 1, wherein The magnetron further comprises a support portion, a cover portion and a fixing bolt, the support portion being arranged between the load base and the cover portion, the cover portion and the support portion being fixed to the support portion by the fixing bolt.

7. The magnetron of claim 6, wherein The magnetic pole units are arranged in a ring shape on the load base, and the support portion is further arranged between each of the magnetic pole units arranged in the ring shape.

8. The magnetron of claim 1, wherein Each of the magnetic pole units comprises one first magnetic pole and two second magnetic poles arranged on opposite sides of the first magnetic pole, respectively; or each of the magnetic pole units comprises one second magnetic pole and two first magnetic poles arranged on opposite sides of the second magnetic pole, respectively.

9. The magnetron of claim 1, wherein The magnetron further comprises a driving portion, the driving portion being arranged on an axial center line of the magnetron.

10. A magnetron sputtering device, characterized by The magnetron sputtering device comprises the magnetron according to any one of claims 1-9.

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