JP2018107433A - Focus ring and substrate processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce leakage of heat transfer gas.SOLUTION: The focus ring surrounds a periphery of a substrate placed on a stage in a processing chamber of a substrate processing apparatus. When provided to be opposed to the peripheral edge portion of the stage, a lower surface of the focus ring has an inclined portion inclined in a predetermined range in a direction following the inclination of the peripheral portion of the stage.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a focus ring and a substrate processing apparatus.

  In the processing chamber of the substrate processing apparatus, a focus ring is provided on the periphery of the substrate placed on the electrostatic chuck so as to surround the substrate. The focus ring converges the plasma toward the surface of the wafer W when plasma processing is performed in the processing chamber, and improves the processing efficiency.

  The focus ring is generally made of Si (silicon), and the inclination of the lower surface of the silicon is managed from ± a few μm from a flat state without inclination. In recent years, for the purpose of extending the life of the focus ring, a more rigid material represented by SiC (silicon carbide) has been adopted as the material of the focus ring.

  A heat transfer gas such as He (helium) is supplied to the lower surface of the focus ring disposed on the peripheral edge of the electrostatic chuck, thereby controlling the temperature of the focus ring. In Patent Document 1, in order to suppress an increase in the amount (leakage) of the supplied heat transfer gas leaking from the gap between the focus ring and the electrostatic chuck, during wafer loading / unloading and waferless dry cleaning (WLDC), It has been proposed to electrostatically attract the focus ring.

Japanese Patent Laid-Open No. 2006-122740 JP, 2006-225588, A

  The electrostatic chuck has a structure in which the peripheral portion is lowered from the central portion for convenience of fixing on the stage with screws on the outer peripheral side of the stage. At this time, when the focus ring is made of Si, since Si is a material softer than SiC, the focus ring fits the inclination of the electrostatic chuck. For this reason, the clearance gap between a focus ring and an electrostatic chuck becomes narrow, and it can suppress that heat transfer gas leaks.

  However, when the focus ring is made of SiC, since SiC is harder than Si, there is a problem that the gap between the focus ring and the electrostatic chuck is not narrowed and the heat transfer gas leaks significantly.

  In view of the above problem, in one aspect, the present invention aims to reduce leakage of heat transfer gas.

  In order to solve the above-described problem, according to one aspect, the focus ring surrounds a peripheral edge of a substrate placed on a stage in a processing chamber of a substrate processing apparatus, and the lower surface of the focus ring is formed on the stage. There is provided a focus ring having an inclined portion that is inclined in a predetermined range in a direction following the inclination of the peripheral portion of the stage when provided opposite to the peripheral portion of the stage.

  According to another aspect, a stage in the processing chamber, an electrostatic chuck provided on the stage, a first suction electrode provided in a central portion of the electrostatic chuck, and a peripheral edge of the electrostatic chuck A second attracting electrode provided on the electrostatic chuck and a focus ring surrounding the periphery of the substrate placed on the electrostatic chuck, and the lower surface of the focus ring is above the peripheral edge of the stage. A substrate processing apparatus is provided that has an inclined portion that is inclined within a predetermined range in a direction that follows the inclination of the peripheral edge of the stage.

  According to another aspect, the focus ring surrounds the periphery of the substrate placed on the stage in the processing chamber of the substrate processing apparatus, and the upper surface of the focus ring has the first flat portion and the first flat portion. A second flat portion lower than the flat portion, and the first flat portion is disposed so as to surround the periphery of the substrate on the substrate side from the second flat portion, and has a thickness equal to or more than the thickness of the sheath. A focus ring is provided having a width of

  According to another aspect, the focus ring surrounds the periphery of the substrate placed on the stage in the processing chamber of the substrate processing apparatus, and the lower surface of the focus ring is opposed to the periphery of the stage. Provided, the upper surface of the focus ring is more than the first flat portion and the first flat portion, and has an inclined portion inclined in a predetermined range in a direction following the inclination of the peripheral portion of the stage. The first flat portion is disposed so as to surround the periphery of the substrate on the substrate side from the second flat portion, and has a width equal to or greater than the thickness corresponding to the sheath. A focus ring is provided.

  According to another aspect, a stage in the processing chamber, an electrostatic chuck provided on the stage, a first suction electrode provided in a central portion of the electrostatic chuck, and a peripheral edge of the electrostatic chuck A second attracting electrode provided on the part, and a focus ring surrounding a periphery of the substrate placed on the electrostatic chuck, and an upper surface of the focus ring includes a first flat part and the focus ring A second flat portion lower than the first flat portion, and the first flat portion is disposed so as to surround the periphery of the substrate on the substrate side from the second flat portion, and corresponds to a sheath. A substrate processing apparatus having a width equal to or greater than a thickness is provided.

  According to another aspect, a stage in the processing chamber, an electrostatic chuck provided on the stage, a first suction electrode provided in a central portion of the electrostatic chuck, and a peripheral edge of the electrostatic chuck A second attracting electrode provided on the electrostatic chuck and a focus ring surrounding the periphery of the substrate placed on the electrostatic chuck, and the lower surface of the focus ring is above the peripheral edge of the stage. And an inclined portion that is inclined in a predetermined range in a direction that follows the inclination of the peripheral edge of the stage, and the upper surface of the focus ring has a first flat portion and the first A second flat portion lower than the flat portion, and the first flat portion is disposed so as to surround the periphery of the substrate on the substrate side from the second flat portion, and has a thickness equal to or more than the thickness of the sheath. A substrate processing apparatus having the following width is provided.

  According to one aspect, leakage of heat transfer gas can be reduced.

The figure which shows an example of the substrate processing apparatus which concerns on one Embodiment. The figure which shows an example of the shape of the lower surface of the focus ring which concerns on one Embodiment. The figure which shows an example of the curvature of the electrostatic chuck which concerns on one Embodiment. The figure which shows an example of the curvature amount of the electrostatic chuck which concerns on one Embodiment. The figure which shows an example of the conditions for measuring the leakage amount of the heat transfer gas by the focus ring which concerns on one Embodiment. The figure which shows an example of the leak amount of the heat transfer gas by the focus ring which concerns on one Embodiment. The figure which shows an example of the material of a focus ring which concerns on one Embodiment, and a physical-property value. The figure which shows an example of the focus ring and temperature uniformity which concern on one Embodiment. The figure which shows the other example of the focus ring which concerns on one Embodiment. The figure for demonstrating the fluctuation | variation of the etching rate and tilting by consumption of a focus ring. The figure which shows an example of the leak amount of the heat transfer gas by the focus ring which concerns on one Embodiment. The figure which shows an example of the focus ring which concerns on the modification 1 of one Embodiment. The figure which shows an example of the focus ring which concerns on the modification 2 of 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.

[Overall configuration of substrate processing apparatus]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of a substrate processing apparatus 1 according to an embodiment. In the present embodiment, an example in which the substrate processing apparatus 1 disclosed in the present application is an RIE (Reactive Ion Etching) type substrate processing apparatus 1 will be described. However, the substrate processing apparatus 1 may be applied to a plasma etching apparatus or a plasma CVD apparatus using surface wave plasma.

  The substrate processing apparatus 1 has a cylindrical processing vessel 10 made of metal, for example, aluminum or stainless steel, and the inside thereof is a processing chamber in which plasma processing such as plasma etching and plasma CVD is performed. The processing container 10 is grounded.

  A disc-shaped stage (lower electrode) 11 on which a wafer W as an object to be processed (substrate) is placed is disposed inside the processing container 10. This stage 11 has a base material 11a, and has an electrostatic chuck 25 on the base material 11a. The base material 11 a is made of, for example, aluminum, and is supported by a cylindrical support portion 13 that extends vertically upward from the bottom of the processing container 10 via an insulating cylindrical holding member 12.

  An exhaust path 14 is formed between the side wall of the processing container 10 and the cylindrical support portion 13. An annular baffle plate 15 is provided at the entrance or in the middle of the exhaust passage 14, and an exhaust port 16 is provided at the bottom. An exhaust device 18 is connected to the exhaust port 16 via an exhaust pipe 17. The exhaust device 18 has a vacuum pump and depressurizes the processing space in the processing container 10 to a predetermined degree of vacuum. The exhaust pipe 17 has an automatic pressure control valve (hereinafter referred to as “APC”) which is a variable butterfly valve, and the APC automatically controls the pressure in the processing vessel 10. Further, a gate valve 20 that opens and closes the loading / unloading port 19 for the wafer W is attached to the side wall of the processing container 10.

  A first high-frequency power source 21 for plasma generation and RIE is electrically connected to the stage 11 via a matching unit 21a. The first high-frequency power source 21 applies predetermined first high-frequency power, for example, power having a frequency of 40 MHz to the stage 11.

  A second high frequency power supply 22 for applying a bias is electrically connected to the stage 11 via a matching unit 22a. The second high frequency power supply 22 applies a second high frequency power lower than the first high frequency, for example, a power having a frequency of 3 MHz to the stage 11.

  Further, a gas shower head 24 as an upper electrode having a ground potential described later is disposed on the ceiling of the processing container 10. As a result, high frequency power from the first high frequency power supply 21 is applied between the stage 11 and the gas shower head 24.

  An electrostatic chuck 25 is provided on the upper surface of the stage 11 to attract the wafer W with an electrostatic attraction force. The electrostatic chuck 25 includes a disc-shaped central portion 25a on which the wafer W is placed and an annular peripheral portion 25b. The height of the central portion 25a is higher than the height of the peripheral portion 25b. . A focus ring 30 that surrounds the periphery of the substrate in an annular shape is placed on the upper surface of the periphery 25b.

  The central portion 25a is configured by sandwiching an electrode plate 25c made of a conductive film between a pair of dielectric films. The peripheral portion 25b is configured by sandwiching an electrode plate 25d made of a conductive film between a pair of dielectric films. A DC power source 26 is electrically connected to the electrode plate 25 c via a switch 27. DC power supplies 28-1 and 28-2 are electrically connected to the electrode plate 25d via switches 29-1 and 29-2. The electrostatic chuck 25 generates an electrostatic force such as a Coulomb force by a DC voltage applied to the electrode plate 25c from the DC power supply 26, and attracts and holds the wafer W on the electrostatic chuck 25 by the electrostatic force. The electrostatic chuck 25 generates an electrostatic force such as a Coulomb force by a DC voltage applied to the electrode plate 25d from the DC power supplies 28-1 and 28-2, and the electrostatic ring 25 causes the focus ring 30 to be attached to the electrostatic chuck 25 by the electrostatic force. Hold by adsorption. The electrode plate 25 c is an example of a first suction electrode provided in the central portion 25 a of the electrostatic chuck 25, and the electrode plate 25 d is a second suction electrode provided in the peripheral portion 25 b of the electrostatic chuck 25. It is an example.

  For example, an annular refrigerant chamber 31 extending in the circumferential direction is provided inside the stage 11. A coolant having a predetermined temperature, for example, cooling water, is circulated and supplied from the chiller unit 32 to the coolant chamber 31 via pipes 33 and 34, and the processing temperature of the wafer W on the electrostatic chuck 25 is controlled by the temperature of the coolant. To do.

  Further, a heat transfer gas supply unit 35 is connected to the electrostatic chuck 25 via a gas supply line 36. The gas supply line 36 is branched into a wafer side line 36 a that reaches the central portion 25 a of the electrostatic chuck 25 and a focus ring side line 36 b that reaches the peripheral edge portion 25 b of the electrostatic chuck 25.

  The heat transfer gas supply unit 35 supplies the heat transfer gas to a space sandwiched between the central portion 25a of the electrostatic chuck 25 and the wafer W using the wafer side line 36a. Further, the heat transfer gas supply unit 35 supplies the heat transfer gas to a space sandwiched between the peripheral edge 25b of the electrostatic chuck 25 and the focus ring 30 using the focus ring side line 36b. As the heat transfer gas, a gas having thermal conductivity, such as He gas, is preferably used.

  The gas shower head 24 at the ceiling has an electrode plate 37 on the lower surface and an electrode support 38 that detachably supports the electrode plate 37. The electrode plate 37 has a large number of gas ventilation holes 37a. A buffer chamber 39 is provided inside the electrode support 38, and a gas supply pipe 41 from the processing gas supply unit 40 is connected to a gas introduction port 38 a of the buffer chamber 39. In addition, around the processing container 10, a magnet 42 that extends in an annular or concentric manner is disposed.

  Each component of the substrate processing apparatus 1 is connected to the control unit 43. The control unit 43 controls each component of the substrate processing apparatus 1. For example, the exhaust device 18, the first high-frequency power source 21, the second high-frequency power source 22, the electrostatic chuck switches 27, 29-1 and 29-2, and the DC power sources 26, 28-1 and 28- 2, chiller unit 32, heat transfer gas supply unit 35, process gas supply unit 40, and the like.

  The control unit 43 includes a CPU 43a and a memory 43b (storage device), and controls a desired substrate processing in the substrate processing apparatus 1 by reading and executing a program and a processing recipe stored in the memory 43b. Further, the control unit 43 controls an electrostatic adsorption process for electrostatically adsorbing the focus ring 30 and a heat transfer gas supply process for supplying a heat transfer gas according to the substrate process.

  In the processing container 10 of the substrate processing apparatus 1, a horizontal magnetic field directed in one direction is formed by the magnet 42. Further, an RF electric field in the vertical direction is formed by the high frequency power applied between the stage 11 and the gas shower head 24. As a result, magnetron discharge through the processing gas is performed in the processing container 10, and high-density plasma is generated from the processing gas in the vicinity of the surface of the stage 11.

In the substrate processing apparatus 1, during the dry etching process, the gate valve 20 is first opened, and the wafer W to be processed is loaded into the processing container 10 and placed on the electrostatic chuck 25. Then, a processing gas (for example, a mixed gas composed of C ₄ F ₈ gas, O ₂ gas and Ar gas having a predetermined flow rate ratio) is introduced into the processing container 10 from the processing gas supply unit 40 at a predetermined flow rate and flow rate ratio. Then, the pressure in the processing container 10 is set to a predetermined value by the exhaust device 18 or the like. Further, high frequency power is supplied from the first high frequency power supply 21 and the second high frequency power supply 22 to the stage 11, and a DC voltage is applied from the DC power supply 26 to the electrode plate 25 c of the electrostatic chuck 25, so that the wafer W is placed on the electrostatic chuck 25. Adsorb to. Heat transfer gas is supplied to the wafer W and the back surface of the focus ring 30. Then, the processing gas discharged by the gas shower head 24 is turned into plasma, and a predetermined plasma processing is performed on the surface of the wafer W by radicals and ions in the plasma.

[Inclined part of focus ring]
Next, the configuration of the focus ring 30 according to the present embodiment will be described with reference to FIG. The lower surface of the focus ring 30 according to the present embodiment is in a direction that follows the inclination of the peripheral portion 25b of the electrostatic chuck 25 when the focus ring 30 is provided on the peripheral portion 25b of the electrostatic chuck 25. It has an inclined portion 30a that is inclined by a predetermined range.

  As shown in FIG. 3, the electrostatic chuck 25 is fixed to the base material 11 a with a screw 72 at a peripheral edge 25 b of the electrostatic chuck 25. The focus ring 30 is installed on the peripheral edge portion 25 b via the portion 25 f of the electrostatic chuck 25 on the screw 72.

  An O-ring 70 on the inner peripheral side and an O-ring 71 on the peripheral edge are provided between the base 11 a and the electrostatic chuck 25 inside the portion fixed by the screw 72. With such a structure, the reaction force of the O-ring 70 on the center portion 25 a side of the electrostatic chuck 25 and the reaction force of the O-ring 71 on the peripheral edge portion 25 b side and the fixing by the screw 72 cause the center portion 25 a of the electrostatic chuck 25. Rises higher than the peripheral edge 25b. Thereby, the electrostatic chuck 25 is deformed into a shape in which the peripheral edge portion 25b is lower than the central portion 25a.

  FIG. 4 shows an example of the amount of warping of the electrostatic chuck 25 according to an embodiment. FIG. 4 shows the state of warping of the focus ring attracting surface (peripheral portion 25 b) of the electrostatic chuck 25. According to this, it can be seen that the focus ring attracting surface of the electrostatic chuck 25 is warped.

  When the focus ring 30 according to the present embodiment is formed of SiC, since SiC is harder than Si, it does not fit the inclination of the electrostatic chuck 25. For this reason, if the back surface of the focus ring 30 is not inclined, the gap between the electrostatic chuck 25 and the electrostatic chuck 25 does not adhere, and heat transfer gas leaks.

  Therefore, the focus ring 30 according to the present embodiment includes an inclined portion 30a that is inclined in a direction following the inclination of the peripheral edge portion 25b of the electrostatic chuck 25. Thereby, the clearance gap between the focus ring 30 and the electrostatic chuck 25 is narrowed, and leakage of heat transfer gas can be reduced.

[Inclination of focus ring]
The inclination of the lower surface of the focus ring 30 is 10 μm to 20 μm as shown in S of FIG. 2 with respect to 38 mm indicating the width + α on the electrostatic chuck 25 out of the radial width of the focus ring 30. It falls to the outer peripheral side in the range of. That is, the inclination angle θ with respect to the horizontal direction is preferably about 0.03 ° when the inclination is 10 μm and about 0.06 ° when the inclination is 20 μm, that is, a range of 0.03 ° to 0.06 °. . Hereinafter, the reason why a numerical value in this range is preferable will be described.

  Experiments were conducted on the amount of heat transfer gas leakage by changing the degree of inclination of the lower surface of the focus ring 30. The experimental conditions are shown in FIG. 5, and the experimental results are shown in FIG. As shown in FIG. 5, the experiment of the heat transfer gas leakage amount was performed for three different steps of (a) Condition 1, (b) Condition 2, and (c) Condition 3.

  (A) In condition 1, the pressure condition of the plasma process is 10 mT (1.33 Pa), the effective power of the first high-frequency power is 525 W, and the effective power of the second high-frequency power is 4900 W.

  (B) In condition 2, the pressure condition of the plasma process is 10 mT (1.33 Pa), the effective power of the first high-frequency power is 300 W, and the effective power of the second high-frequency power is 2800 W.

  (C) In condition 3, the pressure condition of the plasma process is 15 mT (2.00 Pa), the effective power of the first high-frequency power is 1200 W, and the effective power of the second high-frequency power is 8400 W.

  Under these conditions, He gas was supplied as a heat transfer gas during the plasma process using the substrate processing apparatus 1. An experiment was performed using one electrostatic chuck 25. Each of FIG. 6A to FIG. 6C shows an experimental result in one electrostatic chuck 25. 6A to 6C, when the inclination of the lower surface of the focus ring 30 shown on the horizontal axis is changed, the vertical direction of FIGS. 6A to 6C is changed. A change similar to the amount of He gas leakage shown on the shaft occurred. 6 indicates the degree of inclination of the lower surface of the focus ring 30, and the vertical axis in FIG. 6 indicates the amount of heat transfer gas (He) leakage.

  When the value shown on the horizontal axis is negative, the lower surface of the focus ring 30 is inclined so that the inner peripheral side is lower than the outer peripheral side. When the value shown on the horizontal axis is positive, the lower surface of the focus ring 30 is inclined so that the outer peripheral side is lower than the inner peripheral side in the range of 10 μm to 20 μm, as shown in S of FIG.

  As a result, in any case of condition 1 in FIG. 6A, condition 2 in FIG. 6B, condition 3 in FIG. 6C, the leakage amount of the heat transfer gas (He) is on the inner peripheral side. It can be seen that it is the smallest when it is inclined to be lower in the range of 10 μm to 20 μm. That is, the lower surface of the focus ring 30 is inclined in the radial direction of the focus ring 30 such that the outer peripheral side of the focus ring 30 is lower than the inner peripheral side, and the inclination is 10 μm in the size of the focus ring 30 described above. It can be seen that it is preferably in the range of ˜20 μm.

  When the inclination is smaller than the lower limit (10 μm) of the above range, it is impossible to suppress the heat transfer gas from leaking from the outer peripheral side of the focus ring 30. On the other hand, when the inclination is larger than the upper limit value (20 μm) of the above range, it becomes impossible to prevent the heat transfer gas from leaking from the inner peripheral side of the focus ring 30. Therefore, the inclination of the focus ring 30 is set lower on the outer peripheral side than on the inner peripheral side in the range of 10 μm to 20 μm. Thereby, it can suppress that heat transfer gas leaks from the lower surface of the focus ring 30.

[Focus ring material]
As shown in FIG. 7, the focus ring 30 is made of SiC (silicon carbide), W (tungsten), WC (tungsten carbide), and ceramics, which are harder than Si (silicon) having a Young's modulus of 1.30 × 10 ^11. There may be. Further, the focus ring 30 may be not only a material harder than Si but also Si or SiO ₂ .

The Young's modulus of SiC (silicon carbide) is 4.30 × 10 ¹¹ (Pa), the Young's modulus of W (tungsten) is 4.11 × 10 ¹¹ (Pa), and the Young's modulus of WC (tungsten carbide). The rate is 5.50 × 10 ¹¹ (Pa). Furthermore, the Young's modulus of the ceramic is 1.80 × 10 ¹¹ (Pa).

The focus ring 30 according to the present embodiment has a Young's modulus in the range of 5.0 × 10 ^{10 to} 1.0 × 10 ¹² (Pa), including the Young's modulus of Si, SiO ₂ , SiC, W, WC, and ceramics. A substance is preferred.

  In particular, when the focus ring 30 is formed of SiC (silicon carbide), it is preferable because the Si (silicon) conventionally used focus ring 30 has similar properties such as resistance to a plasma process.

[Temperature control of focus ring]
Next, the shape and temperature control of the back surface of the focus ring 30 will be described with reference to FIG. In the case 1 of FIG. 8A, there is no inclined portion on the back surface of the focus ring 30 as shown in the cross-sectional view, and it is flat. In the case 2 of FIG. 8B, there is no inclined portion on the back surface of the focus ring 30 as shown in the cross-sectional view, and an annular groove portion is provided above the focus ring side line 36b for supplying the heat transfer gas on the electrostatic chuck 25 side. 30b is formed.

  As shown in the top view of FIG. 8A and the top view of FIG. 8B, heat transfer gas is introduced from the gas hole H at the tip of the focus ring side line 36 b toward the back surface of the focus ring 30. As a result, in the case 2, the heat transfer gas is diffused in the space in the groove 30b, so that the heat transfer gas leakage can be further reduced as compared with the case 1, and the temperature control of the focus ring 30 becomes better. Uniformity of distribution is achieved.

  Note that the result of this experiment is not the result of directly measuring the temperature of the focus ring 30. The temperature uniformity in the focus ring 30 in this experiment is determined by unevenness (non-uniformity) in the distribution of reaction products attached to the focus ring 30. If the temperature is non-uniform, noticeable unevenness appears in the distribution of reaction products attached to the focus ring 30. Therefore, in this experiment, temperature uniformity in the focus ring 30 was determined based on whether or not the distribution of the reaction product was uneven.

In this experiment, the thickness L of the focus ring 30 was 3.35 mm. The experiment was performed by setting the depth G1 and the width G2 of the groove 30b to the following four patterns.
(1) Depth G1 0.5mm Width G2 2.2mm
(2) Depth G1 0.1mm Width G2 2.2mm
(3) Depth G1 0.1 mm Width G2 5.6 mm
(4) Depth G1 0.05mm Width G2 5.6mm
In any pattern, by providing the groove 30b on the back surface of the focus ring 30 at a position facing the gas hole H of the heat transfer gas, the temperature in the focus ring 30 is higher than that in the case 1 of FIG. It was found that the distribution was uniform.

  Therefore, as shown in FIG. 9A, in the focus ring 30 according to the present embodiment, an inclined portion having an inclination of 10 μm to 20 μm on the lower surface thereof in a direction following the inclination of the peripheral edge portion 25 b of the electrostatic chuck 25. 30a may be provided, and a groove 30b may be formed on the inclined surface. The formed groove 30b may be an annular groove extending in the circumferential direction, or may be a plurality of non-annular recesses formed above the plurality of gas holes H of the heat transfer gas. .

  As shown in FIG. 9B, the focus ring 30 according to the present embodiment includes three parts 30c, 30d, and 30e. The height of the central part 30d in the height direction is set to the parts 30c on both sides and The groove 30b may be formed by making it shorter than the length of 30e. That is, the groove part 30b is formed from the level | step difference of three parts 30c, 30d, and 30e. Further, by providing the groove portion 30b of the focus ring 30 according to the present embodiment at a position facing the gas hole H of the heat transfer gas, leakage of the heat transfer gas can be reduced, and the temperature distribution in the focus ring 30 is made uniform. be able to.

  The focus ring 30 according to the present embodiment may be configured by three parts 30c, 30d, and 30f shown in FIG. In this case, the focus ring 30 forms a groove 30b by making the length in the height direction of the central part 30d shorter than the lengths of the parts 30c and 30f on both sides, as in FIG. 9B. Also good. The shape of the outermost peripheral portion of the focus ring 30 may be provided with corners as shown in a part 30e in FIG. 9B, or may be rounded as shown in a part 30f in FIG. 9C.

  Instead of the groove 30b in FIGS. 9A to 9C, as shown in FIG. 9D, a groove 30g bent inside may be used. The bending of the groove 30g may be directed inward, outward, or both sides.

  As shown in FIGS. 9A to 9D, the lower surface of the focus ring 30 is tilted within a predetermined range, and the groove 30b and the groove 30g are provided to reduce heat transfer gas leakage, thereby increasing the temperature. Uniformity of distribution can be achieved. It is preferable that at least a part of the groove formed on the lower surface of the focus ring 30 is provided at a position facing the gas hole H of the heat transfer gas.

  As described above, according to the focus ring 30 of the present embodiment, the lower surface has the inclined portion 30a that is inclined within a predetermined range. Thereby, the focus ring 30 fits to the inclination of the electrostatic chuck 25, and leakage of heat transfer gas can be reduced.

  In addition, providing the groove portion in the inclined portion 30a further reduces the leakage of heat transfer gas, facilitates diffusion of the heat transfer gas supplied to the lower surface of the focus ring 30, and makes the temperature distribution of the focus ring 30 uniform. Can be improved.

[Modification 1]
Next, before describing the configuration of the focus ring 30 according to the first modification of the embodiment of the present invention, the state of the sheath due to wear of the focus ring 30 will be described with reference to FIG.

  As shown in FIG. 10A, the focus ring 30 is designed so that the upper surface of the wafer W and the upper surface of the focus ring 30 have the same height, for example, in the case of a new product. At this time, the sheath on the wafer W during the plasma processing and the sheath on the focus ring 30 have the same height. In this state, the irradiation angle of ions onto the wafer W and the focus ring 30 is vertical, and as a result, the etching shape such as holes formed on the wafer W is formed vertically, and the etching shape is slanted. Tilting does not occur. Further, the etching rate becomes uniform over the entire surface of the wafer W.

  However, during the plasma processing, the focus ring 30 is exposed to plasma and consumed. Then, as shown in FIG. 10B, the upper surface of the focus ring 30 is lower than the upper surface of the wafer W, and the height of the sheath on the focus ring 30 is lower than the height of the sheath on the wafer W.

  As a result, the ion irradiation angle becomes oblique at the edge portion of the wafer W where the height of the sheath is stepped, and etching-shaped tilting occurs. In addition, the etching rate of the edge portion of the wafer W varies, and the etching rate in the plane of the wafer W becomes non-uniform.

  On the other hand, as described above, when the focus ring 30 shown in FIG. 10A is made of SiC, since SiC is harder than Si, the electrostatic chuck 25 has a structure higher than that when the focus ring is made of Si. It is difficult to fit the tilt. For this reason, there is a problem that the amount of heat transfer gas such as He supplied to the back surface of the focus ring 30 leaks from the gap between the back surface of the focus ring 30 and the electrostatic chuck 25.

  FIG. 11 shows an example of He gas leakage when the focus ring 30 is made of SiC. The horizontal axis in FIG. 11 indicates the amount of He gas supplied to the back surface of the focus ring 30, and the vertical axis in FIG. 6 indicates the amount of He gas that leaks from the gap between the back surface of the focus ring 30 and the electrostatic chuck 25. The left side of FIG. 11 shows the results when the SiC focus ring 30 having a thickness of 3.35 mm is used, and the right side shows the results when the SiC focus ring 30 having a thickness of 3.5 mm is used.

According to this, when the focus ring 30 having a thickness of 3.35 mm is used, it can be seen that about 2 sccm of He gas leaks. Furthermore, it can be seen that when the focus ring 30 having a thickness of 3.5 mm is used, about 3.5 sccm of He gas leaks. That is, when a substance such as SiC having a Young's modulus of 5.0 × 10 ^{10 to} 1.0 × 10 ¹² (Pa) is used for the focus ring 30, it can be seen that the amount of He gas leakage varies depending on the thickness.

  Therefore, in the first modification of the present embodiment, the shape and thickness of the upper surface of the focus ring 30 are devised as shown in FIG. Specifically, the upper surface of the focus ring 30 according to the first modification has a first flat portion 30h and a second flat portion 30i lower than the first flat portion 30h. The first flat portion 30h is disposed so as to surround the periphery of the wafer W on the wafer W side from the second flat portion 30i.

  According to this configuration, by forming the second flat portion 30 i lower than the first flat portion 30 h on the upper surface of the focus ring 30, the strength is reduced on the outer peripheral side of the focus ring 30. Thereby, it is possible to reduce leakage of heat transfer gas from the gap between the back surface of the focus ring 30 and the electrostatic chuck 25.

  Furthermore, a first flat portion 30 h is formed on the upper surface of the focus ring 30 according to the first modification so as to surround the periphery of the wafer W, and the thickness of the upper surface of the focus ring 30 near the periphery of the wafer W is not reduced. . Thereby, the tilting of the etching shape can be prevented.

  Specifically, the width D of the first flat portion 30h is preferably formed to a thickness corresponding to the sheath or more. The thickness of the sheath varies depending on the DC voltage applied from the direct current power source, but is approximately in the range of 5 mm to 10 mm. Therefore, it is preferable that the first flat portion 30h has a width in the range of 5 mm to 10 mm or a width of 10 mm or more.

  By making the width D of the first flat portion 30h equal to or greater than the thickness corresponding to the sheath, the sheath can be prevented from being inclined at the edge portion or the like of the wafer W. That is, in the present modification, the first flat portion 30h has a width D equal to or greater than the thickness corresponding to the sheath, and therefore corresponds to the width D rather than the edge portion of the wafer W, as shown in FIG. There is a step in the height of the sheath on the outside by the distance. Thereby, it is possible to prevent the tilting of the etching shape from occurring at the edge portion or the like of the wafer W. In addition, the uniformity of the etching rate can be achieved.

  The height B of the first flat portion 30h of the focus ring 30 shown in FIG. 12A is determined according to the process conditions, and is preferably the same as or close to the upper surface of the wafer W.

  The height C of the second flat portion 30i of the focus ring 30 is determined by the gradient tolerance of the focus ring 30, the gradient tolerance of the electrostatic chuck 25, and the physical property value (Young's modulus, etc.) of the material of the focus ring 30.

  The height C of the second flat part 30i may or may not be constant. For example, the height C of the second flat portion 30i may be flat or gradually decreased toward the outer peripheral side. Further, the height C of the second flat portion 30i may be lower at the center than at the inner side and the outer side. However, the height C of the second flat portion 30i is at least lower than the height B of the first flat portion 30h. That is, the strength of the second flat portion 30i is designed to be lower than the strength of the first flat portion 30h.

  According to the focus ring 30 according to the first modification, the amount of heat transfer gas leakage can be reduced by forming the second flat portion 30i lower than the first flat portion 30h on the upper surface of the focus ring 30. it can. In addition to this, it is possible to prevent the etching shape from tilting at the edge portion of the wafer W, and to achieve a uniform etching rate.

  Note that the focus ring 30 according to the first modification can be applied to the substrate processing apparatus 1 described in the above embodiment. Thereby, the leakage amount of the heat transfer gas can be reduced, and even after the focus ring 30 is consumed by the plasma processing, the occurrence of tilting of the etching shape can be prevented and the etching rate can be made uniform.

[Modification 2]
Next, a focus ring 30 according to Modification 2 of the present embodiment will be described with reference to FIG. FIGS. 13A and 13B are diagrams illustrating an example of the focus ring 30 according to the second modification of the embodiment of the present invention.

  The focus ring 30 according to the modified example 2 has both the inclined portion on the lower surface of the focus ring described in the above embodiment and the configuration of the upper surface of the focus ring 30 described in the modified example 1. The difference between FIG. 13 (a) and FIG. 13 (b) is that in FIG. 13 (b) there is a dent in the heat transfer gas inlet on the electrostatic chuck 25 side, whereas FIG. 13 (a). Then, the introduction port of the heat transfer gas on the electrostatic chuck 25 side is a flat point.

  That is, the lower surface of the focus ring 30 according to the modified example 2 follows the inclination of the peripheral edge 25b of the electrostatic chuck 25 when the focus ring 30 is provided on the peripheral edge of the electrostatic chuck 25. It has an inclined portion 30a that is inclined by a predetermined range. The inclination of the lower surface of the focus ring 30 in the inclined part 30a falls to the outer peripheral side in the range of 10 μm to 20 μm, as shown in S of FIG. That is, the inclination angle θ with respect to the horizontal direction is about 0.03 ° when the inclination is 10 μm, about 0.06 ° when the inclination is 20 μm, that is, an angle in the range of 0.03 ° to 0.06 °. Is preferred.

  As shown in FIGS. 13A and 13B, the upper surface of the focus ring 30 according to the second modification has the same configuration as the focus ring 30 according to the first modification, and the first flat portion 30 h and the first A second flat portion 30i lower than the flat portion 30h. The first flat portion 30h is disposed so as to surround the periphery of the wafer W on the wafer W side from the second flat portion 30i. The width D of the first flat portion 30h is equal to or greater than the thickness corresponding to the sheath, and the first flat portion 30h preferably has a width in the range of 5 mm to 10 mm or a width of 10 mm or more.

  With this configuration, the focus ring 30 according to the second modification has a feature related to the lower surface of the focus ring 30 according to one embodiment of the present invention and a feature related to the upper surface of the focus ring 30 according to the first modification. Thereby, according to the focus ring 30 which concerns on the modification 2, the leakage of heat transfer gas can be reduced more. In addition, it is possible to prevent the etching shape from tilting and to achieve a uniform etching rate.

  Note that the focus ring 30 according to the modified example 2 can be applied to the substrate processing apparatus 1 described in the above embodiment. Thereby, the amount of heat transfer gas leakage can be further reduced. In addition, even after the focus ring 30 is consumed by the plasma treatment, the etching shape can be prevented from being tilted, and the etching rate can be made uniform.

  The focus ring and the substrate processing apparatus have been described in the above embodiment. However, the focus ring and the substrate processing apparatus according to the present invention are not limited to the above embodiment, and various modifications and improvements can be made within the scope of the present invention. Is possible. The matters described in the above embodiments can be combined within a consistent range.

  For example, the present invention is applicable not only to the parallel plate type two-frequency application device of FIG. 1 but also to other substrate processing apparatuses. Other substrate processing apparatuses include a capacitively coupled plasma (CCP) apparatus, an inductively coupled plasma (ICP) processing apparatus, a substrate processing apparatus using a radial line slot antenna, and a helicon wave excitation type. A plasma (HWP) device, an electron cyclotron resonance plasma (ECR) device, a surface wave substrate processing device, or the like may be used.

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

DESCRIPTION OF SYMBOLS 1 Substrate processing apparatus 10: Processing container 11: Stage (lower electrode)
15: Baffle plate 18: Exhaust device 21: First high frequency power source 22: Second high frequency power source 24: Gas shower head (upper electrode)
25: Electrostatic chuck 30: Focus ring 25c: Electrode plate 25d: Electrode plate 26: DC power supply 28-1: DC power supply 28-2: DC power supply 30: Focus ring 30a: Inclined part 30b: Groove part 30c-30f: Parts 30g : Groove part 31: Refrigerant chamber 32: Chiller unit 35: Heat transfer gas supply part 70: O-ring 71: O-ring W: Wafer H: Gas hole

Claims (16)

A focus ring surrounding the periphery of the substrate placed on the stage in the processing chamber of the substrate processing apparatus,
When the lower surface of the focus ring is provided opposite to the periphery of the stage, the focus ring has an inclined portion that is inclined in a predetermined range in a direction following the inclination of the periphery of the stage. The focus ring is formed of a material having a Young's modulus of 5.0 × 10 ^{10 to} 1.0 × 10 ¹² (Pa).
The focus ring according to claim 1. The focus ring is formed of any one of SiC, Si, SiO ₂ , W, WC, or ceramics.
The focus ring according to claim 1 or 2. The inclined portion is inclined in a range of 10 μm to 20 μm in a direction following the inclination of the peripheral edge of the stage.
The focus ring as described in any one of Claims 1-3. A groove is formed on the inclined surface of the inclined portion.
The focus ring as described in any one of Claims 1-4. An annular groove is formed on the inclined surface of the inclined portion.
The focus ring according to claim 5. A bent groove is formed on the inclined surface of the inclined portion.
The focus ring according to claim 5. A stage in the processing chamber;
An electrostatic chuck provided on the stage;
A first attracting electrode provided at a central portion of the electrostatic chuck;
A second attracting electrode provided at a peripheral edge of the electrostatic chuck;
A focus ring that surrounds the periphery of the substrate placed on the electrostatic chuck;
The substrate processing apparatus, wherein the lower surface of the focus ring has an inclined portion inclined in a predetermined range in a direction following the inclination of the peripheral edge of the stage when the lower surface of the focus ring is provided facing the peripheral edge of the stage. A groove is formed on the inclined surface of the inclined portion.
The substrate processing apparatus according to claim 8. The groove is provided at a position facing a gas hole at a tip of a heat transfer gas supply line provided in the substrate processing apparatus.
The substrate processing apparatus according to claim 9. A focus ring surrounding the periphery of the substrate placed on the stage in the processing chamber of the substrate processing apparatus,
The upper surface of the focus ring has a first flat part and a second flat part lower than the first flat part,
The first flat portion is disposed so as to surround the periphery of the substrate on the substrate side from the second flat portion, and has a width equal to or greater than a thickness corresponding to the sheath. A focus ring surrounding the periphery of the substrate placed on the stage in the processing chamber of the substrate processing apparatus,
The lower surface of the focus ring has an inclined portion that inclines in a predetermined range in a direction that follows the inclination of the peripheral portion of the stage when provided facing the peripheral portion of the stage.
The upper surface of the focus ring has a first flat part and a second flat part lower than the first flat part,
The first flat portion is disposed so as to surround the periphery of the substrate on the substrate side from the second flat portion, and has a width equal to or greater than a thickness corresponding to the sheath. The thickness corresponding to the sheath is included in the range of 5 mm to 10 mm.
The focus ring according to claim 11 or 12. The first flat portion has a height that is the same as or close to the upper surface of the substrate.
The focus ring according to any one of claims 11 to 13. A stage in the processing chamber;
An electrostatic chuck provided on the stage;
A first attracting electrode provided at a central portion of the electrostatic chuck;
A second attracting electrode provided at a peripheral edge of the electrostatic chuck;
A focus ring that surrounds the periphery of the substrate placed on the electrostatic chuck;
The upper surface of the focus ring has a first flat part and a second flat part lower than the first flat part,
The first flat portion is a substrate processing apparatus which is disposed so as to surround the periphery of the substrate on the substrate side from the second flat portion and has a width equal to or greater than a thickness corresponding to a sheath. A stage in the processing chamber;
An electrostatic chuck provided on the stage;
A first attracting electrode provided at a central portion of the electrostatic chuck;
A second attracting electrode provided at a peripheral edge of the electrostatic chuck;
A focus ring that surrounds the periphery of the substrate placed on the electrostatic chuck;
The lower surface of the focus ring has an inclined portion that inclines in a predetermined range in a direction that follows the inclination of the peripheral portion of the stage when provided facing the peripheral portion of the stage.
The upper surface of the focus ring has a first flat part and a second flat part lower than the first flat part,
The first flat portion is a substrate processing apparatus which is disposed so as to surround the periphery of the substrate on the substrate side from the second flat portion and has a width equal to or greater than a thickness corresponding to a sheath.