JP2017191751A - Component and plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a component for a plasma processing device having high adhesion and followability while maintaining plasma resistance.SOLUTION: There is provided a component which is used in a plasma processing device. The component is formed by a graphite material whose surface is covered with SiC. When the component is arranged in the plasma processing device, the thickness of SiC of a surface opposite to plasma generated inside of the plasma processing device is formed thicker than that of SiC of a surface other than the surface opposite to the plasma, and the thickness of SiC of the surface other than the surface opposite to the plasma is equal to or more than 20 μm.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a component and a plasma processing apparatus.

  Conventionally, a technique is known in which a graphite material whose surface is coated with a SiC (silicon carbide) film is used for a member such as a heater embedded in a mounting table of a plasma processing apparatus (for example, Patent Document 1). 2). The member having such a configuration is excellent in plasma resistance because the surface is covered with the SiC film.

JP 2004-75493 A Japanese Patent Laid-Open No. 2-164783

  However, in Patent Documents 1 and 2, since the SiC coated on the surface of the graphite material is a hard material, depending on the shape and thickness of the SiC, the graphite material for the member on the apparatus side when placed in the plasma processing apparatus In some cases, the adhesion and follow-up property of the film become poor. In particular, during the process, when the inside of the processing vessel becomes high temperature due to heat input of plasma, the state of the contact surface between the graphite material and the device-side member that contacts the graphite material changes, and the graphite material with respect to the device-side member In some cases, the adhesion and the follow-up property may deteriorate.

  With respect to the above-described problem, an object of one aspect of the present invention is to provide a component for a plasma processing apparatus having high adhesion and followability while maintaining plasma resistance.

  In order to solve the above problems, according to one aspect, a component used in a plasma processing apparatus, wherein the component is formed of a graphite material whose surface is coated with SiC, and the component is the plasma processing When arranged in the apparatus, the thickness of SiC on the surface facing the plasma generated inside the plasma processing apparatus is formed thicker than SiC on the surface other than the surface facing the plasma, and faces the plasma. A component is provided in which the thickness of the SiC other than the surface is 20 μm or more.

  According to one aspect, it is possible to provide a component for a plasma processing apparatus having high adhesion and followability while maintaining plasma resistance.

The figure which shows an example of the longitudinal cross-section of the plasma processing apparatus which concerns on one Embodiment. The figure which shows an example of the cross section of the focus ring which concerns on one Embodiment. The figure for demonstrating the simulation of the displacement amount of the focus ring which concerns on one Embodiment. The figure which shows an example of the simulation result of the displacement amount of the focus ring which concerns on one Embodiment. The figure which shows an example of the simulation result of the thickness and displacement amount of the SiC film which concerns on one Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, in this specification and drawing, about the substantially same structure, the duplicate description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[Plasma processing equipment]
First, an example of a configuration of a plasma processing apparatus 1 according to an embodiment of the present invention will be described with reference to a longitudinal section of the plasma processing apparatus 1 in FIG. In the present embodiment, a capacitively coupled plasma processing apparatus will be described as an example of the plasma processing apparatus 1. The plasma processing executed in the plasma processing apparatus 1 according to the present embodiment is not particularly limited, but etching processing on a semiconductor wafer (hereinafter referred to as “wafer”) or film formation processing by a CVD (Chemical Vapor Deposition) method. May be included. In the production of a focus ring, which will be described later, when a SiC film is coated on a graphite material, the SiC film can be formed on the graphite material substrate by the CVD method using the plasma processing apparatus 1.

  The plasma processing apparatus 1 includes a processing container 10 made of a conductive material such as aluminum. The processing container 10 is electrically grounded. A mounting table 11 is disposed inside the processing container 10. The stage 12 of the mounting table 11 is supported by a support 13, and an electrostatic chuck 14 for electrostatically attracting the wafer W is provided at an upper position thereof. The electrostatic chuck 14 has a structure in which a chuck electrode 14a is sandwiched between insulators 14b. A DC power supply 32 is connected to the chuck electrode 14a. When a direct current is supplied from the direct current power source 32 to the chuck electrode 14 a, a Coulomb force is generated, and the wafer W is electrostatically attracted to the electrostatic chuck 14. As a result, the wafer W is held on the mounting table 11. On / off of the current supplied from the DC power supply 32 is controlled by the switch 31.

  A ring-shaped focus ring 15 is disposed on the outer edge portion of the electrostatic chuck 14 in order to improve the in-plane uniformity of etching. The focus ring 15 is made of a graphite material covered with a SiC film.

  A high frequency power source 34 is connected to the mounting table 11 via a matching unit 35. For example, a high frequency of 13.56 MHz is applied to the mounting table 11 from the high frequency power supply 34. With this configuration, the mounting table 11 also functions as a lower electrode. The matching unit 35 matches the load impedance to the internal (or output) impedance of the high-frequency power source 34. Thereby, when plasma is generated in the processing container 10, the internal impedance and the load impedance of the high frequency power supply 34 seem to coincide with each other.

  A gas shower head 21 is provided on the ceiling surface of the processing vessel 10 via a shield ring 22 that covers the peripheral edge. In the gas shower head 21, a diffusion chamber 24 and a large number of gas flow paths 25 are formed. The gas output from the gas supply source 33 is introduced into the diffusion chamber 24 through the gas inlet 23. The gas diffused in the diffusion chamber 24 is introduced into the processing vessel 10 from the gas holes 26 through a large number of gas flow paths 25. Thereby, the gas shower head 21 introduces gas into the processing container 10 in a shower shape. Further, the gas shower head 21 is arranged in parallel to face the mounting table 11, and has the function of the upper electrode with respect to the function of the lower electrode of the mounting table 11.

  An exhaust port 28 is formed in the bottom surface of the processing container 10, and the inside of the processing container 10 is exhausted by an exhaust device 36 connected to the exhaust port 28. Thereby, the inside of the processing container 10 is controlled to a predetermined degree of vacuum.

  A gate valve 27 is provided on the side wall of the processing vessel 10. The gate valve 27 opens and closes when the wafer W is loaded into the processing container 10 and the wafer W is unloaded from the processing container 10.

  When performing plasma processing such as etching in the plasma processing apparatus 1 having such a configuration, first, the wafer W is carried into the processing container 10 from the opened gate valve 27 while being held on the transfer arm. . The gate valve 27 is closed after the wafer W is loaded. The pressure in the processing container 10 is reduced to a set value by the exhaust device 36.

  The wafer W is held by pusher pins above the electrostatic chuck 14, and is placed on the electrostatic chuck 14 by the pusher pins being lowered. A desired current is supplied from the DC power supply 32 to the chuck electrode 14 a of the electrostatic chuck 14, whereby the wafer W is electrostatically attracted onto the electrostatic chuck 14.

  A desired etching gas is introduced into the processing container 10 from the gas shower head 21, and high frequency power of 13.56 MHz, for example, is applied to the mounting table 11 from the high frequency power supply 34. The introduced etching gas is dissociated and ionized by the high-frequency power, thereby generating plasma. A desired plasma process is performed on the wafer W by the action of the generated plasma. After the etching is completed, the wafer W is held on the transfer arm and is carried out of the processing container 10 through the opened gate valve 27.

[Focus ring structure]
Next, the structure of the focus ring 15 according to the present embodiment will be described with reference to FIG. FIG. 2 shows an example of a cross section of the focus ring 15 according to the present embodiment. The focus ring 15 has a ring shape, and one cross section of the ring is shown in FIG.

  The focus ring 15 according to the present embodiment is formed of a graphite material 15a whose surface is covered with a SiC film 15b. The SiC film 15b is formed over the entire surface of the graphite material 15a serving as a base material. In the present embodiment, the SiC film 15b is formed by a CVD method.

  SiC has high plasma resistance and radical resistance. For example, SiC has higher plasma resistance than Si. In contrast, graphite has low plasma resistance and radical resistance. For this reason, it is preferable that the surface of the graphite material 15a serving as the base material of the focus ring 15 is coated with SiC having excellent plasma resistance.

  In addition, a large number of bubbles exist inside the graphite. Therefore, it is necessary to cover the entire surface of the graphite material 15a with the SiC film 15b. Thereby, it is possible to prevent the outgas from being released from the portion of the graphite material 15a not covered with the SiC film 15b. Thereby, the influence on the process by the pressure inside the processing container 10 fluctuating and the influence on the process by the outgas itself from the graphite material 15a can be avoided.

  SiC is a hard material. For this reason, when the focus ring 15 is formed only of SiC, when the inside of the processing vessel 10 becomes high temperature due to heat input of plasma during the process, the contact surface between the SiC and the apparatus side member (in FIG. 2). The adhesion and followability of the upper surface 14c) of the electrostatic chuck 14 may deteriorate. Further, depending on the shape of SiC, it is difficult to machine hard SiC, and processing takes time.

  For this reason, the focus ring 15 according to the present embodiment has a base material of the graphite material 15a inside, and has a double structure in which the entire surface is covered with the SiC film 15b, so that plasma resistance, adhesion, and follow-up are achieved. It has a structure that balances sex. That is, the surface of the focus ring 15 is coated with the SiC film. For this reason, plasma resistance is high. On the other hand, the inside of the focus ring 15 is formed of a soft graphite material. For this reason, when the focus ring 15 becomes high temperature due to heat input from the plasma during the process, the focus ring 15 easily adheres to the adsorption surface 14c by the soft graphite material 15a, and the electrostatic adsorption force received from the electrostatic chuck 14 It is easy to follow. Thereby, the followability with respect to the upper surface (attraction surface) 14c of the electrostatic chuck 14, that is, the attraction to the electrostatic chuck 14 can be improved.

  Furthermore, the flexible graphite material is easily machined when the focus ring 15 according to the present embodiment is manufactured. Therefore, after the upper part on the inner peripheral side of the graphite material 15a is shaved and the inner peripheral side thickness of the graphite material 15a is processed to be thin, the SiC film 15b is coated on the surface to machine SiC. Easier to manufacture. Thereby, the machining time of the focus ring 15 can be shortened. Further, the focus ring 15 according to the present embodiment can be manufactured by leaving the graphite material originally used as the base material when the SiC film 15b is formed by the CVD method.

  Of the SiC film 15 b that coats the graphite material 15 a of the focus ring 15, the SiC film 15 b on the upper surface 15 b 1 is a surface facing the plasma generated inside the plasma processing apparatus 1. For this reason, the SiC film 15b on the upper surface 15b1 is exposed to the plasma during the process, and is consumed by the attack of ions or the like in the plasma as compared with the surfaces other than the upper surface (the lower surface 15b2 and the side surface 15b3). For this reason, the thickness of the SiC film 15b on the upper surface 15b1 is formed thicker than the SiC film 15b on the surface other than the upper surface 15b1, and a sufficient thickness is required. For example, the thickness Tp of the SiC film 15b on the upper surface 15b1 may be about 1 mm.

  Thus, plasma resistance can be enhanced by making the SiC film 15b on the upper surface 15b1 thicker than the SiC film 15b on the lower surface 15b2 and the side surface 15b3. Further, by forming the SiC film 15b on the lower surface 15b2 thinner than the SiC film 15b on the upper surface 15b1, adhesion to the upper surface 14c of the electrostatic chuck 14 can be improved. Thereby, the followability (adsorption property) of the focus ring 15 to the electrostatic chuck 14 can be enhanced. For example, the thickness Tnp of the SiC film 15b on the lower surface 15b2 and the side surface 15b3 of the focus ring 15 may be about 0.1 mm.

  The thickness of the SiC film 15b on the lower surface 15b2 and the side surface 15b3 of the focus ring 15 needs to be 20 μm or more. The reason will be described. The surface roughness Ra of the machined graphite material 15a is about 2 to 5 μm, and the surface roughness Ra after the SiC film 15b is coated on the surface of the graphite material 15a is also about 2 to 5 μm. For this reason, the SiC film 15b formed on the surface of the graphite material 15a completely fills the irregularities generated on the surfaces of the graphite material 15a and the SiC film 15b, and the SiC film 15b is sufficiently formed in the subsequent processing. In order not to expose the graphite material 15a, a minimum thickness of 20 μm is required. Therefore, the lower limit of the thickness of the lower surface 15b2 and the side surface 15b3 is 20 μm.

[Displacement of focus ring]
Below, the simulation result of the displacement amount of a focus ring is demonstrated, referring FIG.3 and FIG.4. First, the conditions of this simulation will be described with reference to FIG. The focus ring 15 is in contact with the electrostatic chuck 14 on the lower surface 15b2 of the focus ring 15 in a state in which the lower end A on the inner peripheral side is completely fixed, and the portion attracted to the electrostatic chuck 14 is equivalent to 50 Torr (6666 Pa). Pull down with the force of. The displacement of the central portion B of the lower surface 15b2 of the focus ring 15 at this time is calculated as the displacement amount of the focus ring 15.

  In this simulation, the thickness of the upper surface 15b1 of the focus ring 15 obtained by coating the graphite material 15a according to this embodiment shown in FIG. 3 with the SiC film 15b is 1 mm, and the thickness of the lower surface 15b2 and the side surface 15b3 is 0. 1 mm. In this simulation, a focus ring 15 having a double structure of the graphite material 15a and the SiC film 15b according to the present embodiment, a focus ring having the same shape as that of the present embodiment, and formed integrally with Si, The amount of displacement with a focus ring integrally formed of SiC is compared.

In this simulation, the physical properties of Young's modulus and Poisson's ratio of each of Si (silicon), SiC, and graphite shown in FIG. 4A were used. As a result, as shown in FIG. 4B, in this simulation, the displacement amount of the focus ring 15 in which the graphite material 15a is coated with the SiC film 15b is 1.53 × 10 ⁻⁶ (m). The displacement amount of the SiC focus ring was 3.40 × 10 ⁻⁷ (m), and the displacement amount of the Si focus ring was 1.07 × 10 ⁻⁶ (m).

  As a result, it is found that the largest displacement amount when the focus ring is pulled downward with the same force is the focus ring 15 according to this embodiment in which the graphite material 15a is coated with the SiC film 15b. It was. When SiC and Si are compared, the SiC focus ring is harder than the Si focus ring and has a small displacement.

  From the above, it was found that the focus ring 15 in which the graphite material 15a is coated with the SiC film 15b is more easily deformed than the Si focus ring and the SiC focus ring, and has good adhesion and followability to the electrostatic chuck 14. . As a result, it has been found that the focus ring 15 having such a configuration has high adsorbability to the electrostatic chuck 14.

[Displacement of focus ring]
Next, when the ratio (= Tnp / Tp) of the thickness Tnp of the SiC film 15b of the lower surface 15b2 (and the side surface 15b3) to the thickness Tp of the SiC film 15b of the upper surface 15b1 of the focus ring 15 according to the present embodiment is changed. A simulation result of the displacement amount of the focus ring 15 will be described. FIG. 5 shows an example of the simulation result of the thickness and displacement of the SiC film according to the present embodiment.

  The horizontal axis of the graph shown in FIG. 5 is Tnp / Tp, and the vertical axis shows the displacement amount of the central portion B of the lower surface 15b2 of the focus ring 15 according to the present embodiment shown in FIG. When Tnp / Tp = 100% = 1/1, the thickness Tp of the SiC film 15b on the upper surface 15b1 and the thickness Tnp of the lower surface 15b2 (and the side surface 15b3) are the same. When Tnp / Tp = 10% = 1/10, the thickness Tnp of the lower surface 15b2 (and the side surface 15b3) is 1/10 with respect to the thickness Tp of the SiC film 15b on the upper surface 15b1.

  According to the simulation result of the displacement amount of the focus ring 15 when Tnp / Tp is changed in FIG. 5, it can be seen that the displacement amount of the focus ring 15 increases as the value of Tnp / Tp decreases. That is, it can be seen that the displacement amount of the focus ring 15 increases as the thickness Tnp of the lower surface 15b2 (and the side surface 15b3) with respect to the thickness Tp of the SiC film 15b on the upper surface 15b1 decreases.

  Further, comparing the displacement amount of the focus ring integrally formed of Si in FIG. 5 with the displacement amount of the focus ring formed of SiC, the value of Tnp / Tp of the focus ring 15 according to the present embodiment is It is preferably 100% or less, which indicates that the focus ring is more easily deformed than a focus ring integrally formed of SiC.

  Further, the value of Tnp / Tp of the focus ring 15 according to the present embodiment is more preferably 25% or less indicating that the focus ring 15 is more easily deformed than the focus ring formed of Si.

  As described above, the focus ring 15 according to the present embodiment has a double structure in which the graphite material 15a is provided inside and the outside is covered with the SiC film 15b. Thereby, it is possible to form the focus ring 15 that is more easily deformed than the focus ring formed of SiC or Si alone. Thereby, according to the focus ring 15 which concerns on this embodiment, the adhesiveness to the adsorption surface of the electrostatic chuck 14 and followable | trackability can be improved.

  In addition, according to the focus ring 15 according to the present embodiment, the life of the focus ring 15 can be extended by covering the outside with the SiC film 15b that is plasma resistant and is not easily consumed.

  In the focus ring 15 according to the present embodiment, the plasma resistance can be increased by making the thickness of the SiC film 15b on the upper surface 15b1 of the focus ring 15 exposed to plasma larger than the thickness of the other surfaces.

  Furthermore, in the focus ring 15 according to the present embodiment, the thickness of the SiC film 15b other than the upper surface 15b1 is such that the irregularities generated on the surfaces of the graphite material 15a and the SiC film 15b are completely filled, and the subsequent processing is also performed. Since the SiC film 15b remains sufficiently, it has a thickness of at least 20 μm. Thereby, it is possible to prevent the graphite material 15a from being exposed due to a crack or the like of the SiC film 15b and generating outgas from the graphite material 15a.

  In the embodiment described above, the dual structure focus ring 15 having the graphite material 15a inside and having the entire surface of the graphite material 15a covered with the SiC film 15b has been described. However, a double-structured component having a graphite material inside and having the entire surface of the graphite material covered with a SiC film is not limited to the focus ring 15 and can be applied to a component disposed inside the plasma processing apparatus. That is, the upper surface 15b1 of the focus ring 15 is an example of a surface facing the plasma, and the surface facing the plasma is determined depending on the arrangement position of the components. In the present embodiment, the lower surface 15b2 and the side surface 15b3 of the focus ring 15 shown as surfaces other than the upper surface 15b1 of the focus ring 15 are examples of surfaces other than the surface facing the plasma. A surface other than the opposing surface is determined.

  According to the component for the plasma processing apparatus having the double structure, the adhesion and followability of the contact surface between the component and the component at the arrangement position when the component is arranged in the plasma processing apparatus are maintained while maintaining the plasma resistance. Can be increased.

  As mentioned above, although the part and plasma processing apparatus which are used for a plasma processing apparatus were demonstrated by the said embodiment, the parts and plasma processing apparatus which are used for the plasma processing apparatus concerning this invention are not limited to the said embodiment. Various modifications and improvements are possible within the scope of the present invention. The matters described in the above embodiments can be combined within a consistent range.

  For example, the focus ring 15 according to the present invention is applicable not only to a capacitively coupled plasma (CCP) apparatus but also to other plasma processing apparatuses. Other plasma processing apparatuses include an inductively coupled plasma (ICP) processing apparatus, a plasma processing apparatus using a radial line slot antenna, a helicon wave excited plasma (HWP) apparatus, and an electron cyclotron resonance. A plasma (ECR: Electron Cyclotron Resonance Plasma) apparatus or the like may be used.

  In the present specification, the semiconductor wafer W has been described as an object of plasma processing. However, the present invention is not limited to this, and various substrates used for LCD (Liquid Crystal Display), FPD (Flat Panel Display), photomasks, CD substrates, It may be a printed circuit board or the like.

DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 10 Processing container 11 Mounting stand (lower electrode)
14 Electrostatic chuck 14a Chuck electrode 15 Focus ring 15a Graphite material 15b SiC film 21 Gas shower head (upper electrode)
DESCRIPTION OF SYMBOLS 22 Shield ring 23 Gas introduction port 24 Diffusion chamber 25 Gas flow path 26 Gas hole 27 Gate valve 28 Exhaust port 32 DC power source 33 Gas supply source 34 High frequency power source 35 Matching device 36 Exhaust device

Claims (5)

Parts used in a plasma processing apparatus,
The component is formed of a graphite material whose surface is coated with SiC,
When the component is placed in the plasma processing apparatus, the thickness of SiC on the surface facing the plasma generated inside the plasma processing apparatus is formed thicker than that on the surface other than the surface facing the plasma. ,
The thickness of SiC of surfaces other than the surface which opposes the said plasma is 20 micrometers or more. The component is a focus ring disposed on an outer edge portion of a mounting table inside the plasma processing apparatus.
The component according to claim 1. The surface facing the SiC plasma is the upper surface of the focus ring,
The thickness of SiC on the surface other than the upper surface of the focus ring is ¼ or less of the thickness of SiC on the upper surface.
The component according to claim 2. The focus ring has a mechanism that is electrostatically attracted to an electrostatic chuck provided on the mounting table.
The component according to claim 2 or 3. A processing container in which plasma processing is performed on the substrate by plasma generated inside;
A mounting table disposed inside the processing container and mounting a substrate;
A focus ring disposed on the outer edge of the mounting table,
The focus ring is formed of a graphite material whose surface is coated with SiC,
The thickness of SiC on the upper surface of the focus ring is formed thicker than SiC on the surface other than the upper surface,
The thickness of SiC on the surface other than the upper surface is 20 μm or more.
Plasma processing equipment.

Images