Plasma processing apparatus

Abstract

To generate plasma with a reduced capacitive coupling component inside a vacuum vessel.SOLUTION: A plasma processing apparatus (1) comprises: a vacuum vessel (2); an antenna (7) which generates a high-frequency magnetic field; and a magnetic field introduction window (3) which introduces the high-frequency magnetic field into the vacuum vessel (2). The magnetic field introduction window (3) has: a metal plate (4) provided with a plurality of slits (41); and a dielectric plate (5) which overlaps the metal plate (4) in a manner covering the plurality of slits (41) and is provided with a metal layer (6). The metal layer (6) is kept at a predetermined potential.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a plasma processing apparatus.

Background Art

[0002] Patent Document 1 discloses a plasma processing apparatus including a metal plate in which a slit is formed, a dielectric plate that is supported in contact with the metal plate and closes the slit, and an antenna that is provided outside the processing chamber so as to face the metal plate and generates a high-frequency magnetic field. The plasma processing apparatus disclosed in Patent Document 1 can efficiently supply the high-frequency magnetic field generated from the antenna to the processing chamber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the plasma processing apparatus disclosed in Patent Document 1 has a problem that an electrostatically coupled plasma component is generated inside the processing chamber.

[0005] One aspect of the present invention aims to generate plasma with suppressed electrostatically coupled components inside a vacuum vessel.

Means for Solving the Problems

[0006] In order to solve the above problems, a plasma processing apparatus according to an aspect of the present invention includes a vacuum chamber that houses an object to be processed therein, an antenna provided outside the vacuum chamber that generates a high-frequency magnetic field, and a magnetic field introduction window provided on a wall surface of the vacuum chamber for introducing the high-frequency magnetic field into the vacuum chamber to generate plasma inside the vacuum chamber. The magnetic field introduction window includes a metal plate in which a plurality of slits are formed, and a dielectric plate that overlaps the metal plate so as to cover the plurality of slits and in which a metal layer is formed. The metal layer is maintained at a predetermined potential.

Effects of the Invention

[0007] According to one aspect of the present invention, high-density plasma can be generated inside the vacuum chamber.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] 〔Embodiment 1〕 <Configuration of Plasma Processing Apparatus 1> FIG. 1 is a cross-sectional view showing a cross-sectional configuration of a plasma processing apparatus 1 according to Embodiment 1 of the present invention. In FIG. 1, the direction in which the antenna 7 extends is the X-axis direction, the direction from the vacuum chamber 2 toward the antenna 7 is the Z-axis direction, and the direction orthogonal to both the X-axis direction and the Z-axis direction is the Y-axis direction.

[0010] As shown in FIG. 1, the plasma processing apparatus 1 performs plasma processing on an object to be processed W1 such as a substrate using an inductively coupled plasma P1. Here, the substrate is, for example, a substrate for a flat panel display (FPD) such as a liquid crystal display or an organic EL display, or a flexible substrate for a flexible display. Further, the object to be processed W1 can be a semiconductor substrate used for various applications. Furthermore, the object to be processed W1 is not limited to a substrate form, such as a tool or the like. The processing performed on the object to be processed W1 is, for example, film formation by plasma CVD (Chemical Vapor Deposition) method or sputtering method, etching by plasma, ashing, removal of a coating film, etc.

[0011] The plasma processing apparatus 1 includes a vacuum chamber 2, a magnetic field introduction window 3, an antenna 7, a high-frequency power source 8, and a holding unit 9. Inside the vacuum chamber 2, a processing chamber 21 that is evacuated and into which gas is introduced is formed. The vacuum chamber 2 is, for example, a metal container. An opening 23 that penetrates in the thickness direction is formed in the wall surface 22 of the vacuum chamber 2. The vacuum chamber 2 is electrically grounded.

[0012] The gas introduced into the processing chamber 21 may be selected according to the processing content to be performed on the object to be processed W1 accommodated in the processing chamber 21. For example, when forming a film on the object to be processed W1 by the plasma CVD method, the gas is a source gas or a gas diluted with a dilution gas such as H2. To give a more specific example, when the source gas is SiH4, an Si film can be formed, when it is SiH4 + NH3, an SiN film can be formed, when it is SiH4 + O2, an SiO2 film can be formed, and when it is SiF4 + N2, an SiN:F film (fluorinated silicon nitride film) can be formed on the object to be processed W1, respectively.

[0013] <Configuration of the magnetic field introduction window 3> The magnetic field introduction window 3 has a metal plate 4 and a dielectric plate 5. The magnetic field introduction window 3 introduces the high-frequency magnetic field generated from the antenna 7 into the processing chamber 21 in order to generate plasma in the processing chamber 21. The metal plate 4 and the dielectric plate 5 are arranged in order in the Z-axis direction.

[0014] The metal plate 4 is provided on the wall surface 22 of the vacuum chamber 2 so as to close the opening 23. A plurality of slits 41 penetrating the metal plate 4 in the Z-axis direction are formed in the metal plate 4. The plurality of slits 41 extend in the Y-axis direction and are arranged in the X-axis direction. The metal plate 4 is arranged to be substantially parallel to the surface of the object to be processed W1.

[0015] The dielectric plate 5 is provided in contact with the metal plate 4 from the outside of the vacuum chamber 2 so as to cover the plurality of slits 41 and overlaps the metal plate 4. Further, the dielectric plate 5 is provided on the surface of the metal plate 4 on the antenna 7 side so as to close the plurality of slits 41 from the outside of the vacuum chamber 2. As a result, the dielectric plate 5 is supported by the metal plate 4, deformation of the dielectric plate 5 can be suppressed, and the strength of the dielectric plate 5 can be substantially improved.

[0016] The entire dielectric plate 5 is made of a dielectric material, and the dielectric plate 5 has a flat plate shape. The material constituting the dielectric plate 5 may be a ceramic such as alumina, silicon carbide or silicon nitride, an inorganic material such as quartz glass or non-alkali glass, or a resin material such as a fluororesin such as Teflon (registered trademark).

[0017] The high-frequency magnetic field generated from the antenna 7 passes through the dielectric plate 5, the metal layer 6 and the plurality of slits 41 and is supplied to the processing chamber 21. The metal layer 6 will be described later. The vacuum in the processing chamber 21 is maintained by the metal plate 4 closing the opening 23 and the dielectric plate 5 closing the plurality of slits 41.

[0018] <Configuration of the metal layer 6> The metal layer 6 is formed on the surface of the dielectric plate 5 on the antenna 7 side. That is, the metal layer 6 is formed on the surface of the dielectric plate 5 opposite to the side in contact with the metal plate 4. The metal layer 6 is formed over the entire surface of the dielectric plate 5. However, the metal layer 6 only needs to be formed on the surface of the dielectric plate 5 so as to cover all of the plurality of slits 41, and it may be formed in a range excluding a part of the surface of the dielectric plate 5. Further, the dielectric plate 5 is provided in a range excluding a part of the surface of the metal plate 4 on the antenna 7 side so as to cover all of the plurality of slits 41. Thereby, the sizes of the dielectric plate 5 and the metal layer 6 can be reduced, and the manufacturing cost of the plasma processing apparatus 1 can be reduced.

[0019] The metal layer 6 is maintained at a predetermined potential. Thereby, since the dielectric plate 5 on which the metal layer 6 maintained at the predetermined potential is formed overlaps the metal plate 4 so as to cover the plurality of slits 41, the electric field from the antenna 7 toward the processing chamber 21 can be blocked by the metal layer 6. Therefore, it is possible to suppress the occurrence of electrostatic coupling between the plasma generated in the processing chamber 21 and the antenna 7.

[0020] Since the occurrence of electrostatic coupling can be suppressed, plasma with suppressed electrostatic coupling components can be generated. In this way, the generation of plasma due to electrostatic coupling is suppressed, and it is possible to suppress the mixing of plasma due to electrostatic coupling into the plasma due to inductive coupling. Therefore, it is possible to reduce the flow of charged particles due to the potential gradient between the plasma generated by electrostatic coupling and the magnetic field introduction window 3 and the energy loss on the inner wall of the vacuum vessel 2 due to the flow, and to generate high-density plasma in the processing chamber 21. Further, it is possible to reduce the charged particles to which kinetic energy is imparted by the potential gradient, reduce the inflow of unnecessary energy to the surface of the object to be processed W1, and reduce the damage to the surface of the object to be processed W1 during film formation and etching.

[0021] Further, by forming the metal layer 6 on the dielectric plate 5, the electric field generated from the antenna 7 can be blocked by the metal layer 6 regardless of the size of the slit 41 formed in the metal plate 4. Thereby, even when the size of the slit 41 is large, it is possible to prevent the electric field generated from the antenna 7 from entering the processing chamber 21. For this reason, a sufficiently large slit 41 can be formed in the metal plate 4, and the high-frequency magnetic field generated from the antenna 7 can be efficiently supplied from the slit 41 to the processing chamber 21, improving the plasma generation efficiency.

[0022] Note that the metal plate 4 transmits the high-frequency magnetic field generated from the antenna 7 into the processing chamber 21 and reduces the entry of the electric field from the outside of the processing chamber 21 into the inside of the processing chamber 21. However, when the metal layer 6 is not formed on the dielectric plate 5, the electric field generated from the antenna 7 penetrates the dielectric plate 5 and the plurality of slits 41, and electrostatic coupling occurs between the plasma generated in the processing chamber 21 and the antenna 7. That is, when the metal layer 6 is not formed on the dielectric plate 5, the electrostatic coupling cannot be sufficiently suppressed.

[0023] Furthermore, the metal layer 6 is maintained at a predetermined potential, for example, by being connected to the ground G1 and being electrically grounded. When the metal layer 6 is electrically grounded, the electric field directed from the antenna 7 to the processing chamber 21 can be efficiently blocked by the metal layer 6.

[0024] As described above, by forming the metal layer 6 on the surface of the dielectric plate 5 opposite to the side in contact with the metal plate 4, as shown in FIG. 1, an electrostatic coupling E1 is generated between the metal layer 6 and the antenna 7. Thereby, it is possible to suppress the occurrence of electrostatic coupling between the plasma generated in the processing chamber 21 and the antenna 7.

[0025] In addition, since the metal layer 6 is formed on the surface of the dielectric plate 5, the shielding effect against the electric field from the antenna 7 toward the processing chamber 21 can be made uniform. Specifically, the metal layer 6 is formed in a film shape on the surface of the dielectric plate 5 by a vacuum evaporation method or a plating method. As a result, since the metal layer 6 is uniformly formed on the surface of the dielectric plate 5, the shielding effect against the electric field from the antenna 7 toward the processing chamber 21 can be made more uniform.

[0026] Note that instead of the metal layer 6, a material that is not a metal, for example, an oxide-based transparent conductive film, may be used. In that case, by combining the transparent conductive film and the glass dielectric plate 5, it becomes possible to confirm the plasma emission distribution from the antenna 7 side, and it also becomes possible to confirm the plasma density distribution or the progress of plasma processing. For example, the progress of etching can be confirmed.

[0027] The thickness T1 of the metal layer 6 shown in FIG. 1 is equal to or less than the skin depth d determined by the frequency of the high-frequency power applied to the antenna 7 by the high-frequency power source 8 and the electrical resistivity of the metal layer 6. The thickness T1 of the metal layer 6 is the thickness along the Z-axis direction. By making the metal layer 6 thinner, the induced current flowing through the metal layer 6 can be reduced, and the introduction efficiency of the high-frequency magnetic field in the magnetic field introduction window 3 can be improved. More specifically, the skin depth d is determined by the material of the metal layer 6, that is, the type of metal, in addition to the frequency of the high-frequency power applied to the antenna 7.

[0028] The skin depth d is as shown in the following formula (1). In formula (1), ρ is the electrical resistivity of the conductor of the metal layer 6, ω is the angular frequency of the current flowing through the antenna 7, and ω = 2πf. f is the frequency of the current flowing through the antenna 7. μ is the magnetic permeability of the metal layer 6.

[0029]

Equation

[0030] The skin depth d is the thickness at which the magnetic field penetrates the conductor and the magnetic field strength decreases to 1 / e (about 0.37). If the thickness T1 of the metal layer 6 is less than or equal to the skin depth d, the high-frequency magnetic field generated from the antenna 7 can penetrate the metal layer 6. e is the base of the natural logarithm, that is, the Napier's number, and has a value of about 2.71828. Thus, the inductive coupling generated between the plasma generated in the processing chamber 21 and the antenna 7 is not suppressed by the metal layer 6, so the density of the plasma generated inside the processing chamber 21 can be maintained high. Note that in order for the metal layer 6 to be uniformly formed on the surface of the dielectric plate 5, the thickness T1 of the metal layer 6 is preferably 1 μm or more regardless of the frequency f.

[0031] <Cross-sectional configuration of the metal layer 6> FIG. 2 is a cross-sectional view showing the cross-sectional configuration near the metal layer 6 formed on the dielectric plate 5 of the magnetic field introduction window 3 provided in the plasma processing apparatus 1 shown in FIG. 1. As shown in FIG. 2, the metal layer 6 may be supported by a resin sheet 60. In this case, the resin sheet 60 is attached to the surface of the dielectric plate 5. The metal layer 6 and the resin sheet 60 constitute a conductive sheet.

[0032] Specifically, the resin sheet 60 has resin layers 61, 62, and the metal layer 6 is sandwiched between the resin layers 61, 62. By using the resin sheet 60 carrying the metal layer 6, a metal layer 6 sufficiently large can be easily formed on the dielectric plate 5, so that a dielectric plate 5 with a sufficiently large metal layer 6 can be manufactured. Thereby, the number of dielectric plates 5 used can be reduced, and the manufacturing efficiency of the magnetic field introduction window 3 can be improved.

[0033] In addition, the dielectric loss tangent tanδ of the resin sheet 60 carrying the metal layer 6 with respect to the frequency of the high-frequency power applied to the antenna 7 is 0.005 or less. When the antenna 7 and the magnetic field introduction window 3 face each other with the resin sheet 60 interposed therebetween, the resin sheet 60 is heated by the high-frequency power. Therefore, if a material with a dielectric loss tangent tanδ of 0.005 or less is used for the resin sheet 60, excessive heating of the resin sheet 60 can be suppressed.

[0034] As the resin sheet 60, for example, a polyimide sheet may be used. When the resin sheet 60 with the metal layer 6 carried thereon is attached to the surface of the dielectric plate 5, the resin layer 61 faces the antenna 7, and the resin layer 62 contacts the dielectric plate 5.

[0035] The antenna 7 is linear and a plurality of antennas are provided outside the vacuum chamber 2 and arranged to face the magnetic field introduction window 3. Each antenna 7 is arranged substantially parallel to the surface of the object to be processed W1. When high-frequency power is applied to the antenna 7 from the high-frequency power supply 8, a high-frequency magnetic field is generated. As a result, an induced electric field is generated in the space inside the processing chamber 21, and an inductively coupled plasma P1 is generated in that space. The holding unit 9 is a stage that is accommodated in the processing chamber 21 and holds the object to be processed W1.

[0036] 〔Embodiment 2〕 Embodiment 2 of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as those described in Embodiment 1 are denoted by the same reference numerals, and the description thereof will not be repeated. FIG. 3 is a cross-sectional view showing the cross-sectional configuration of the plasma processing apparatus 1A according to Embodiment 2 of the present invention.

[0037] As shown in FIG. 3, the plasma processing apparatus 1A is different from the plasma processing apparatus 1 according to Embodiment 1 in that the magnetic field introduction window 3 is changed to the magnetic field introduction window 3A. The magnetic field introduction window 3A of Embodiment 2 is different from the magnetic field introduction window 3 in the location where the metal layer 6 is formed with respect to the dielectric plate 5. Specifically, in the magnetic field introduction window 3A, the metal layer 6 is formed on the side in contact with the metal plate 4 of the dielectric plate 5. In this case, the dielectric plate 5 faces the antenna 7, and the metal layer 6 is disposed between the surface of the metal plate 4 on the antenna 7 side and the dielectric plate 5.

[0038] Thereby, since the metal layer 6 is disposed facing the processing chamber 21 in a vacuum state, the metal layer 6 is less likely to be affected by atmospheric components. Further, by making the potential between the slits 41 of the metal plate 4 the same by the metal layer 6, when charging occurs due to dirt on the portions of the slits 41 and the metal layer 6, it is possible to prevent discharge inside the slits 41 and stably generate plasma.

[0039] Since the metal layer 6 is formed so as to be in contact with the metal plate 4, the metal layer 6 touches the gas in the processing chamber 21 through the slit 41. In order to avoid the metal layer 6 being affected by the gas in the processing chamber 21, it is preferable to avoid using an oxidizing gas such as O2 and NO2, and a gas containing a halogen-based element such as an etching gas such as CF4 as the gas introduced into the processing chamber 21.

[0040] 〔Summary〕 The plasma processing apparatus according to Aspect 1 of the present invention includes a vacuum container that houses an object to be processed therein, an antenna provided outside the vacuum container that generates a high-frequency magnetic field, and for generating plasma inside the vacuum container, a magnetic field introduction window provided on the wall surface of the vacuum container for introducing the high-frequency magnetic field into the vacuum container, the magnetic field introduction window having a metal plate in which a plurality of slits are formed, and a dielectric plate that overlaps the metal plate so as to cover the plurality of slits and in which a metal layer is formed, and the metal layer is configured to be maintained at a predetermined potential.

[0041] In the plasma processing apparatus according to Embodiment 2 of the present invention, in the above Embodiment 1, the metal layer may be configured to be electrically grounded.

[0042] In the plasma processing apparatus according to Embodiment 3 of the present invention, in the above Embodiment 1 or 2, the metal layer may be configured to be formed on the surface of the dielectric plate.

[0043] In the plasma processing apparatus according to Embodiment 4 of the present invention, in any of the above Embodiments 1 to 3, the metal layer may be supported by a resin sheet, and the resin sheet may be attached to the dielectric plate.

[0044] In the plasma processing apparatus according to Embodiment 5 of the present invention, in the above Embodiment 4, the dielectric tangent of the resin sheet with respect to the frequency of the high-frequency power applied to the antenna may be 0.001 or less.

[0045] In the plasma processing apparatus according to Embodiment 6 of the present invention, in any of the above Embodiments 1 to 5, the thickness of the metal layer may be equal to or less than the skin depth determined by the frequency of the high-frequency power applied to the antenna and the electrical resistivity of the metal layer.

[0046] In the plasma processing apparatus according to Embodiment 7 of the present invention, in any of the above Embodiments 1 to 6, the metal layer may be formed on the side opposite to the side in contact with the metal plate of the dielectric plate.

[0047] In the plasma processing apparatus according to Embodiment 8 of the present invention, in any of the above Embodiments 1 to 6, the metal layer may be formed on the side in contact with the metal plate of the dielectric plate.

[0048] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Explanation of Reference Numerals

[0049] 1, 1A, 1B Plasma Processing Apparatus 2 Vacuum Chamber 3, 3A, 3B Magnetic Field Introduction Window 4 Metal Plate 5 Dielectric Plate 6 Metal Layer 7 Antenna 21 Processing Chamber 22 Wall Surface 41 Slit 60 Resin Sheet P1 Plasma tanδ Dielectric Loss Tangent W1 Workpiece

Claims

1. A vacuum chamber for accommodating an object to be processed therein, An antenna provided outside the vacuum chamber for generating a high-frequency magnetic field, A magnetic field introduction window provided on a wall surface of the vacuum chamber for introducing the high-frequency magnetic field into the vacuum chamber to generate plasma inside the vacuum chamber, The magnetic field introduction window includes: A metal plate in which a plurality of slits are formed, A dielectric plate that overlaps the metal plate so as to cover the plurality of slits and in which a metal layer is formed, The metal layer is maintained at a predetermined potential, carried on a resin sheet, and formed on a side of the dielectric plate opposite to a side in contact with the metal plate, The resin sheet is attached to the dielectric plate. A plasma processing apparatus characterized by this.

2. The plasma processing apparatus according to claim 1, wherein the metal layer is electrically grounded.

3. The plasma processing apparatus according to claim 1 or 2, wherein the metal layer is formed on a surface of the dielectric plate.

4. The plasma processing apparatus according to any one of claims 1 to 3, wherein a dielectric loss tangent of the resin sheet with respect to a frequency of high-frequency power applied to the antenna is 0.001 or less.

5. The plasma processing apparatus according to any one of claims 1 to 4, wherein a thickness of the metal layer is equal to or less than a skin depth determined by a frequency of high-frequency power applied to the antenna and an electrical resistivity of the metal layer.

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