Plasma processing apparatus

Abstract

Provided is a plasma processing apparatus that can utilize a linear antenna section and reduce the generation of capacitive coupled plasma. A linear antenna section (3) provided inside a vacuum container includes an antenna conductor (31) in which a high-frequency current flows, and a Faraday shield (33) provided around at least a portion of the antenna conductor (31).

Description

Technical Field

[0001] This invention relates to a plasma processing apparatus that uses plasma to process the object being processed. Background Technology

[0002] Plasma processing apparatuses are known to generate plasma by flowing high-frequency current through antennas, thereby using the plasma to process substrates and other workpieces. For example, the sputtering apparatus described in Patent Document 1 is an apparatus for forming a film on a substrate by sputtering a target with plasma. In this sputtering apparatus, the substrate and the target are held in a vacuum container that is evacuated and supplied with gas, and the plasma is generated by a plurality of linear antennas arranged along the surface of the substrate.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-154875 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] When using a linear antenna, both inductively coupled plasma (ICP) and capacitively coupled plasma (CCP) are generated. In the case of generating the capacitively coupled plasma, high-energy particles can potentially reach the surface of the object being treated because ions are accelerated by the plasma potential.

[0008] An embodiment of the present invention aims to realize a plasma processing apparatus, etc., that utilizes a linear antenna section and can reduce the generation of capacitively coupled plasma.

[0009] Technical means to solve the problem

[0010] To address the aforementioned issues, a plasma processing apparatus according to an embodiment of the present invention includes: a vacuum container housing an object to be processed; and a linear antenna portion disposed inside the vacuum container and used to generate plasma inside the vacuum container, the antenna portion including: an antenna conductor in which a high-frequency current flows; and a Faraday shield disposed around at least a portion of the antenna conductor.

[0011] The effects of the invention

[0012] According to one embodiment of the present invention, a linear antenna section is used, and the generation of capacitively coupled plasma can be reduced. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view schematically illustrating the structure of a plasma processing apparatus according to an embodiment of the present invention.

[0014] Figure 2 This is a perspective view that schematically represents the structure of the antenna section in the plasma processing apparatus.

[0015] Figure 3 yes Figure 2 Arrow view section at line AA.

[0016] Figure 4 This is a perspective view that schematically illustrates the structure of the antenna section in a plasma processing apparatus according to another embodiment of the present invention.

[0017] Figure 5 This is a perspective view that schematically illustrates the structure of the antenna section in a plasma processing apparatus according to another embodiment of the present invention.

[0018] [Explanation of Symbols]

[0019] 1: Plasma processing device

[0020] 2: Vacuum container

[0021] 2a, 2b: Sidewalls

[0022] 3: Antenna section

[0023] 4: High-frequency power supply

[0024] 6: Vacuum exhaust device

[0025] 8: Substrate holder

[0026] 21: Gas inlet

[0027] 22: Wall opening

[0028] 23: Insulator

[0029] 31: Antenna conductor

[0030] 31a, 31b: Ends

[0031] 32: Radome (first insulator)

[0032] 33: Faraday shielding

[0033] 34: Shielding cover (secondary insulator)

[0034] 41: Impedance Variable

[0035] 331: Ring section

[0036] 332: Connecting part

[0037] 333: Slit section Detailed Implementation

[0038] Hereinafter, embodiments of the present invention will be described in detail. Furthermore, for ease of explanation, components having the same function as those shown in each embodiment will be labeled with the same symbols, and their descriptions will be omitted as appropriate.

[0039] [Implementation Method 1]

[0040] Reference Figures 1-3 An embodiment of the present invention will be described.

[0041] (Structure of a plasma processing device)

[0042] Figure 1 This is a schematic cross-sectional view illustrating the structure of the plasma processing apparatus 1 in this embodiment. The plasma processing apparatus 1 is an apparatus that performs plasma processing on a substrate S using plasma P. Examples of processing performed on the substrate S by the plasma processing apparatus 1 include film formation, etching, and ashing using plasma chemical vapor deposition (CVD) or plasma sputtering. Furthermore, the plasma processing apparatus 1 is also referred to as a plasma CVD apparatus when film formation is performed using plasma CVD, a plasma etching apparatus when etching is performed, a plasma ashing apparatus when ashing is performed, and a plasma sputtering apparatus when film formation is performed using plasma sputtering.

[0043] like Figure 1 As shown, the plasma processing device 1 includes a vacuum container 2, an antenna section 3, and a high-frequency power supply 4.

[0044] The vacuum container 2 is, for example, a metal container and is electrically grounded. A substrate S, which is the object to be processed, is housed within the vacuum container 2. The interior of the vacuum container 2 is evacuated by a vacuum exhaust device 6, and a gas G corresponding to the processing performed on the substrate S is introduced through a gas inlet 21. The gas G can be any type of gas commonly used in the plasma processing apparatus 1, and its specific composition is not particularly limited.

[0045] A substrate holder 8 is provided inside the vacuum container 2 to hold the substrate S. A heater for heating the substrate S can be installed in the substrate holder 8, and a bias voltage can also be applied. If the plasma processing apparatus 1 is a plasma sputtering apparatus, a target is further arranged inside the vacuum container 2.

[0046] The antenna section 3 includes an antenna conductor 31 for plasma generation and an antenna cover 32 (first insulator) covering the antenna conductor 31. The antenna section 3 is linear and is arranged facing the substrate S within the vacuum container 2. Specifically, the antenna section 3 is arranged above the substrate S within the vacuum container 2 in a manner that follows the surface of the substrate S (e.g., substantially parallel to the surface of the substrate S). There may be one or more antenna sections 3 arranged within the vacuum container 2.

[0047] The antenna conductor 31 is formed, for example, of copper, aluminum, alloys thereof, stainless steel, etc. The antenna conductor 31 is straight. Alternatively, the antenna conductor 31 may also be cylindrical. In this case, the antenna conductor 31 can be cooled by flowing a cooling medium such as cooling water through the hollow portion inside the antenna conductor 31. Furthermore, the antenna conductor 31 is not limited to the aforementioned shape; for example, it may also be a solid shape without a hollow portion.

[0048] One end 31a of the antenna conductor 31 passes through a wall opening 22 provided on one side wall 2a of the vacuum container 2, and the other end 31b of the antenna conductor 31 passes through a wall opening 22 provided on the other side wall 2b of the vacuum container 2 opposite to the side wall 2a. An insulator (e.g., an insulating flange) 23 is provided at each wall opening 22. The ends 31a and 31b of the antenna conductor 31 are hermetically connected to the insulator 23 using O-rings or the like, and are supported by the vacuum container 2 through the insulator 23. Thus, the antenna conductor 31 is supported in a state of electrical insulation from the vacuum container 2. Furthermore, the material of the insulator 23 may be, for example, ceramic such as alumina, quartz, etc., but is not limited to these.

[0049] The radome 32 is an insulating material that protects the antenna conductor 31. In this embodiment, the radome 32 is a straight tube that covers the antenna conductor 31 and is coaxially positioned with the antenna conductor 31. Both ends of the radome 32 are supported by the insulating material 23 or the antenna conductor 31. The material of the radome 32 is, for example, an insulating material such as quartz, alumina, silicon nitride, silicon carbide, or silicon, but is not limited to these. Alternatively, the radome 32 may also be an insulating material formed on and covered by the surface of the antenna conductor 31.

[0050] The high-frequency power supply 4 is used to supply high-frequency power to the antenna conductor 31. The frequency of the high-frequency voltage applied by the high-frequency power supply 4 to the antenna conductor 31 is, for example, a typical 13.56 MHz, but is not limited thereto.

[0051] The high-frequency power supply 4 is connected to one end 31a of the antenna conductor 31 via an impedance variable 41. The other end 31b of the antenna conductor 31 is electrically grounded, but can also be connected to other antenna conductors 31 via other impedance variable 41s.

[0052] In the plasma processing apparatus 1 of the described structure, high-frequency power is supplied to the antenna conductor 31 from the high-frequency power supply 4 via the impedance variable 41, and a high-frequency current flows in the antenna conductor 31. This generates plasma P within the vacuum container 2. The generated plasma P diffuses to the vicinity of the substrate S or the target, and the aforementioned processing is performed through the plasma P.

[0053] (Structure of Faraday shield)

[0054] Figure 2 This is a perspective view that roughly represents the structure of the antenna section 3. Figure 2 The upper section is a view of antenna section 3 from above. Figure 2 The lower section is a view of antenna section 3 from the side. Figure 3 yes Figure 2 The arrow view section at line AA. Furthermore, in Figure 2 The impedance variable 41 is omitted in the text.

[0055] like Figure 2 and Figure 3 As shown, the antenna section 3 in this embodiment also includes a Faraday shield 33 (hereinafter referred to as "shielding member 33"). The shielding member 33 is disposed on the outer surface of the radome 32 and is electrically grounded. In addition, the shielding member 33 can be directly grounded to the earth or connected to the ground terminal (ground, GND) of the high-frequency power supply 4.

[0056] The shielding element 33 is made of conductive metals such as copper, stainless steel, and aluminum, and is formed through processes such as vapor deposition, plating, and thin-plate bonding. Furthermore, the film thickness of the shielding element 33 only needs to be sufficient to allow for current flow; ideally, it should be between 10 nm and 5 mm.

[0057] The shielding member 33 includes a plurality of ring portions 331 and a plurality of connecting portions 332. The ring portions 331 are arranged on a plane perpendicular to the axis of the antenna conductor 31 and are spaced apart from each other. The connecting portions 332 connect adjacent ring portions 331. Figure 2 and Figure 3 In this example, multiple connecting portions 332 are alternately arranged on the upper and lower parts of the radome 32. That is, each of the multiple ring portions 331 connects two connecting portions 332 from both sides, and the connection positions of the two connecting portions 332 are symmetrical with respect to the center of the ring portion 331. A slit portion 333 is formed by adjacent ring portions 331 and the connecting portions 332 that connect the adjacent ring portions 331.

[0058] In the antenna section 3 of the aforementioned structure, if a high-frequency current flows through the antenna conductor 31, a high-frequency electric field and a high-frequency magnetic field are generated around the antenna conductor 31. At this time, inside the shielding member 33, charged particles move due to the high-frequency electric field, thereby reducing the high-frequency electric field due to the shielding member 33. As a result, the generation of capacitively coupled plasma can be reduced.

[0059] On the other hand, if a high-frequency current flows through the antenna conductor 31, an induced electromotive force is generated in the shield 33 in a direction parallel to the antenna conductor 31. This induced electromotive force generates an induced current in the connection portion 332, but no induced current is generated in the slit portion 333. Therefore, compared to a shield covering the entire periphery of the antenna conductor 31, the induced current is smaller in the shield 33 of this embodiment. As a result, the reduction of the high-frequency magnetic field based on the shield 33 is reduced, and the generation of inductively coupled plasma P can be maintained.

[0060] Furthermore, in this embodiment, the two connection positions in the ring 331 are different. Therefore, the portion between these connection positions in the ring 331 becomes the path for the induced current. Since this path is orthogonal to the current path of the antenna conductor 31, the resistance of this path effectively increases. Consequently, because the induced current decreases, the reduction in the high-frequency magnetic field based on the shield 33 is further reduced, resulting in the reliable maintenance of the generation of inductively coupled plasma P. Additionally, ohmic heating in the shield 33 can be reduced.

[0061] Furthermore, in this embodiment, the two connection points in the ring 331 are symmetrical with respect to the center of the ring 331. As a result, the resistance is effectively maximized. Consequently, since the induced current is minimized, the reduction of the high-frequency magnetic field based on the shield 33 is minimized, and consequently, the generation of the inductively coupled plasma P can be maintained more reliably. Additionally, ohmic heating in the shield 33 can be further reduced.

[0062] (Additional Notes)

[0063] Furthermore, in this embodiment, multiple connecting portions 332 are disposed on the upper and lower portions of the radome 32, but they may also be disposed on both sides of the radome 32. Additionally, the two connecting positions in the ring portion 331 can be different, and may be asymmetrical relative to the center of the ring portion 331.

[0064] Alternatively, the shielding member 33 can also be disposed inside the radome 32. That is, the shielding member 33 can be disposed around the antenna conductor 31 at any position that is not connected to the antenna conductor 31.

[0065] [Implementation Method 2]

[0066] Reference Figure 4 Another embodiment of the present invention will be described. The plasma processing apparatus 1 of this embodiment and... Figures 1-3 Compared to the plasma processing device 1 shown, the antenna section 3 has a different structure, but the other structures are the same.

[0067] Figure 4 This is a perspective view that schematically illustrates the structure of the antenna section 3, and it is a view of the antenna section 3 viewed from above. The antenna section 3 of this embodiment is similar to... Figure 2 and Figure 3 Compared to the antenna section 3 shown, the difference is that it also includes a shield 34 (second insulator), but the rest of the structure is the same.

[0068] The shielding cover 34 is an insulating material that protects the shielding element 33. In this embodiment, the shielding cover 34 is a straight tube that covers the shielding element 33 and is coaxially disposed with the antenna conductor 31. Both ends of the shielding cover 34 are supported by the insulating material 23 or the radome 32. The material of the shielding cover 34 is the same as that that can be used as the radome 32. Alternatively, the shielding cover 34 may be an insulating material formed on and covered by the radome 32 and the shielding element 33.

[0069] According to the structure, the shielding member 33 is covered by the shielding cover 34. This prevents metal particles from adhering to the slit portion 333 of the shielding member 33 and forming a metal film, while the adjacent ring portion 331 is open to the outside of the connecting portion 332.

[0070] (Additional Notes)

[0071] Furthermore, in this embodiment, the shielding member 33 is formed on the outer surface of the radome 32, but it can also be formed on the inner surface of the shielding cover 34 or inside the shielding cover 34.

[0072] [Implementation Method 3]

[0073] Reference Figure 5 Another embodiment of the present invention will be described. The plasma processing apparatus 1 of this embodiment and... Figures 1-4 Compared to the plasma processing device 1 shown, the antenna section 3 has a different structure, but the other structures are the same.

[0074] Figure 5 This is a perspective view that schematically illustrates the structure of the antenna section 3, and it is a view of the antenna section 3 viewed from above. The antenna section 3 of this embodiment is similar to... Figure 4 Compared to the antenna section 3 shown, the difference lies in the omission of the shielding member 33 and shielding cover 34 in the central part of the antenna section 3; the other structures are the same. That is, in this embodiment, the shielding member 33 and shielding cover 34 are provided at both ends of the antenna section 3. Thus, the shielding member 33 and shielding cover 34 can also be provided around a portion of the antenna conductor 31.

[0075] Furthermore, since the vacuum container 2 is grounded, a high-frequency voltage is applied to the antenna conductor 31. As a result, the electric field strength tends to be greater in the region where the antenna conductor 31 is close to the vacuum container 2 compared to other regions.

[0076] In contrast, according to this embodiment, shielding members 33 are provided at both ends of the antenna section 3 where the antenna conductor 31 is close to the vacuum container 2. This reduces the intensity of the electric field in the region where the antenna conductor 31 is close to the vacuum container 2. As a result, the generation of capacitively coupled plasma can be effectively reduced, thereby improving the distribution of inductively coupled plasma P.

[0077] [Example]

[0078] about Figures 1-3 The plasma processing apparatus 1 shown illustrates embodiments in which various modifications are made to the dimensions of the shielding member 33. Here, the slit spacing of the shielding member 33 is... Figure 2 The length represented by SP in the diagram, and the slit width of shielding component 33 are... Figure 2 The length is represented by SW. Furthermore, the shielding element 33 in this embodiment is made of SUS316 with a thickness of 10μm, and the slit width SW is less than 0.5mm.

[0079] The results showed that when the width (SP-SW) of the ring 331 was 15 mm or less, the reduction in magnetic field strength was small and ideal. Furthermore, it was found that when the width of the ring 331 was 5 mm or less, the reduction in magnetic field strength was even smaller and more ideal. In addition, the lower limit of the width of the ring 331 was determined by various conditions such as manufacturing capability and permissible resistance value.

[0080] 〔Summarize〕

[0081] The plasma processing apparatus of Embodiment 1 of the present invention has the following structure: a vacuum container that houses the object to be processed; and a linear antenna portion disposed inside the vacuum container and used to generate plasma inside the vacuum container. The antenna portion includes an antenna conductor in which a high-frequency current flows; and a Faraday shield disposed around at least a portion of the antenna conductor.

[0082] According to the structure described, the electric field generated by the antenna conductor is shielded by a Faraday shield, thus reducing its propagation to the outside. This, in turn, reduces the generation of capacitively coupled plasma.

[0083] The plasma processing apparatus of Embodiment 2 of the present invention is based on Embodiment 1, wherein the Faraday shield is disposed at a position close to the antenna conductor and the vacuum container. In this case, the intensity of the electric field in the region close to the antenna conductor and the vacuum container can be reduced. As a result, the generation of capacitively coupled plasma can be effectively reduced.

[0084] According to Embodiment 1 and Embodiment 2, the plasma processing apparatus of Embodiment 3 of the present invention may include: a plurality of ring portions disposed around the antenna conductor and separated from each other; and a connecting portion connecting adjacent ring portions to each other.

[0085] In this case, a slit is formed by two adjacent rings and a connecting portion that connects the two rings. If a high-frequency current flows through the antenna conductor, an induced current is generated at the connecting portion, but no induced current is generated at the slit. Therefore, compared to a shield covering the entire periphery of the antenna conductor, the induced current is smaller with the Faraday shield. As a result, the reduction in the high-frequency magnetic field generated by the antenna conductor based on the Faraday shield is reduced, maintaining the generation of induced-coupled plasma.

[0086] The plasma processing apparatus of Embodiment 4 of the present invention is based on Embodiment 3, wherein preferably, the two connecting portions respectively connected from both sides of a certain ring portion are at different connection positions from the certain ring portion. In this case, the portion between the connection positions in the certain ring portion becomes the path of the induced current. Since the path is orthogonal to the current path of the antenna conductor, the resistance of the path effectively increases. Therefore, the induced current generated by the high-frequency current in the antenna conductor decreases, and as a result, the reduction of the high-frequency magnetic field generated by the high-frequency current based on the Faraday shielding is further reduced.

[0087] The plasma processing apparatus of Embodiment 5 of the present invention is based on Embodiment 4, wherein, more preferably, the connection positions of the two connecting portions are symmetrical with respect to the center of the ring portion. In this case, the resistance effectively becomes maximum. Therefore, the induced current generated by the high-frequency current in the antenna conductor becomes minimum, and as a result, the reduction of the high-frequency magnetic field generated by the high-frequency current based on the Faraday shielding is minimized.

[0088] The plasma processing apparatus of Embodiment 6 of the present invention is based on Embodiments 3 to 5, wherein preferably, the width of the ring portion is 15 mm or less. In this case, the decrease in the high-frequency magnetic field can be suppressed. Furthermore, the lower limit of the width of the ring portion is determined by various conditions such as manufacturing capability and permissible resistance value.

[0089] The plasma processing apparatus of Embodiment 7 of the present invention is based on Embodiments 1 to 6, wherein preferably, the antenna section further includes a first insulator disposed between the antenna conductor and the Faraday shield. In this case, conduction between the antenna conductor and the Faraday shield can be prevented.

[0090] The plasma processing apparatus of Embodiment 8 of the present invention, based on Embodiments 1 to 7, may further include a second insulating material covering the periphery of the Faraday shield. In this case, it is possible to prevent metal particles from adhering to the Faraday shield and forming a metal film, and the path of the current flowing in the Faraday shield is shortened.

[0091] This invention is not limited to the various embodiments described. Various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of this invention.

Claims

1. A plasma processing apparatus comprising: A vacuum container that holds the object being processed inside; as well as A linear antenna section is disposed inside the vacuum container and is used to generate plasma inside the vacuum container. The antenna section includes: Antenna conductor, in which high-frequency current flows; and A Faraday shield is disposed around at least a portion of the antenna conductor. The Faraday shield includes: Multiple rings are disposed around the antenna conductor and are spaced apart from each other; and The connecting part connects adjacent ring parts to each other. The two connecting parts that connect to each side of a certain ring are at different connection positions from the ring itself.

2. The plasma processing apparatus according to claim 1, wherein the Faraday shield is disposed at a position close to the antenna conductor and the vacuum container.

3. The plasma processing apparatus according to claim 1 or 2, wherein the connection positions of the two connecting portions are symmetrical with respect to the center of the ring portion.

4. The plasma processing apparatus according to claim 1 or 2, wherein the width of the ring is 15 mm or less.

5. The plasma processing apparatus according to claim 1 or 2, wherein the antenna portion further comprises a first insulator disposed between the antenna conductor and the Faraday shield.

6. The plasma processing apparatus according to claim 1 or 2, wherein the antenna portion further comprises a second insulator covering the periphery of the Faraday shield.

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