Edge ring and substrate processing apparatus

Abstract

The present invention provides an edge ring and a substrate processing apparatus capable of reducing the replacement frequency of an edge ring for plasma processing and suppressing the leakage of a heat transfer gas. The edge ring has a ring-shaped first member having a recess in a lower surface and formed of a first material having plasma resistance, and a ring-shaped second member disposed in the recess of the first member and formed of a second material having lower rigidity than the first material.

Description

TECHNICAL FIELD

[0001] The present application relates to an edge ring and a substrate processing apparatus. BACKGROUND

[0002] In plasma processing of a substrate, an edge ring is sometimes arranged along the outer periphery of the substrate arranged in a chamber set to a prescribed vacuum degree. By arranging the edge ring, plasma processing can be performed uniformly in the surface of the substrate.

[0003] Further, in plasma processing of a substrate, the substrate and the edge ring placed on an electrostatic chuck are adsorbed to the electrostatic chuck by electrostatic adsorption force in a state where the substrate and the edge ring are placed on the electrostatic chuck. Further, in order to improve the heat transfer properties between the substrate and the electrostatic chuck and the heat transfer properties between the edge ring and the electrostatic chuck, a heat transfer gas such as He gas is supplied between the electrostatic chuck and the substrate and between the electrostatic chuck and the edge ring.

[0004] In the related art, an edge ring formed of silicon carbide (SiC) (hereinafter sometimes referred to as "SiC edge ring") is known. Since the SiC edge ring has high plasma resistance, the replacement frequency of the edge ring can be reduced.

[0005] Related Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-251723 SUMMARY

[0008] Problems to be Solved by the Invention

[0009] The present application proposes an edge ring capable of reducing the replacement frequency and suppressing the leakage of a heat transfer gas.

[0010] Means of Solving the Problems

[0011] The edge ring of the disclosed mode has a first member in a ring shape and a second member in a ring shape. The first member has a recess in the lower surface and is formed of a first material having plasma resistance. The second member is arranged in the recess of the first member and is formed of a second material having lower rigidity than the first material.

[0012] Effects of the Invention

[0013] By using the edge ring of the present application for plasma processing, the replacement frequency of the edge ring can be reduced and the leakage of the heat transfer gas can be suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a view showing a configuration example of a substrate processing apparatus.

[0015] Figure 2is a view showing an example of an edge ring and a wafer.

[0016] Figure 3 is a view showing a structural example of an edge ring.

[0017] Explanation of Reference Numerals

[0018] W wafer

[0019] ER, ER1 edge ring

[0020] M1, M2 member

[0021] 11 susceptor

[0022] 25 electrostatic chuck

[0023] 100 substrate processing apparatus DETAILED DESCRIPTION

[0024] Hereinafter, an embodiment of the technology of the present application will be described based on the drawings. In the following embodiment, the same reference numerals are assigned to the same structures.

[0025] Structure of Substrate Processing Apparatus

[0026] Figure 1 is a view showing a structural example of a substrate processing apparatus.

[0027] In Figure 1 the substrate processing apparatus 100 has a chamber 10 which is a metal-made processing container made of, for example, aluminum or stainless steel. The chamber 10 is securely grounded.

[0028] Inside the chamber 10, a disc-shaped susceptor 11 is horizontally arranged. The susceptor 11 is arranged on a lower surface of an electrostatic chuck 25 which is capable of placing a semiconductor substrate (hereinafter, sometimes referred to as "wafer W") and an edge ring ER as a processed substrate. Further, the susceptor 11 functions as a lower electrode to which a high-frequency voltage is applied. The susceptor 11 is made of, for example, aluminum, and is supported to a cylindrical support member 13 which extends vertically upward from a bottom of the chamber 10 via an insulating cylindrical holding member 12.

[0029] An exhaust passage 14 is formed between the side wall of the chamber 10 and the cylindrical support portion 13, a ring-shaped baffle 15 is arranged at the inlet or midway of the exhaust passage 14, and an exhaust port 16 is provided at the bottom of the chamber 10, to which an exhaust device 18 is connected via an exhaust pipe 17. The exhaust device 18 has a vacuum pump, which depressurizes the processing space provided by the chamber 10 to a prescribed vacuum degree. The exhaust pipe 17 has an APC (Automatic Pressure Control Valve), which automatically controls the pressure in the chamber 10. Further, a gate valve 20 for opening and closing a wafer W feeding and discharging port 19 is installed in the side wall of the chamber 10.

[0030] The high-frequency power sources 21-1, 21-2 are electrically connected to the susceptor 11 via the matching devices 22-1, 22-2. The high-frequency power source 21-1 applies a high-frequency voltage for generating plasma to the susceptor 11. The high-frequency power source 21-1 applies a high-frequency voltage of 27 to 100 MHz to the susceptor 11, and preferably applies a high-frequency voltage of, for example, 40 MHz to the susceptor 11. Further, the high-frequency power source 21-2 applies a high-frequency voltage for adsorbing ions to the wafer W to the susceptor 11. The high-frequency power source 21-2 applies a high-frequency voltage of 400 kHz to 40 MHz to the susceptor 11, and preferably applies a high-frequency voltage of, for example, 3 MHz to the susceptor 11. The matching device 22-1 matches the output impedance of the high-frequency power source 21-1 to the input impedance on the side of the susceptor 11, and the matching device 22-2 matches the output impedance of the high-frequency power source 21-2 to the input impedance on the side of the susceptor 11.

[0031] A shower head 24, which is an upper electrode at a ground potential, is arranged at the top of the chamber 10.

[0032] An electrostatic chuck 25 is provided on the upper surface of the base 11 and attracts and holds a wafer W and a ring-shaped edge ring ER placed on the electrostatic chuck 25 by electrostatic attraction force. The electrostatic chuck 25 has a center portion 25a of a circular plate shape, an outer peripheral portion 25b of a ring shape, and a base portion 25f of a circular plate shape having a larger diameter than the center portion 25a, and the center portion 25a is protruded upward with respect to the outer peripheral portion 25b. The lower surfaces of the center portion 25a and the outer peripheral portion 25b are joined to the upper surface of the base portion 25f to form the electrostatic chuck 25. The wafer W is placed on the upper surface of the center portion 25a, and the edge ring ER which ring-encloses the center portion 25a is placed on the upper surface of the outer peripheral portion 25b. Further, the center portion 25a is formed by sandwiching an electrode plate 25c made of a conductive film between a pair of dielectric films, and the outer peripheral portion 25b is formed by sandwiching electrode plates 25d, 25e made of a conductive film between a pair of dielectric films. That is, the electrode plates 25c, 25d, 25e are provided inside the electrostatic chuck 25. Further, the electrode plate 25c is provided in a region inside the electrostatic chuck 25 corresponding to the wafer W, and the electrode plates 25d, 25e are provided in regions inside the electrostatic chuck 25 corresponding to the edge ring ER. The electrode plate 25c is electrically connected to a direct current power supply 26, the electrode plate 25d is electrically connected to a direct current power supply 28, and the electrode plate 25e is electrically connected to a direct current power supply 29. The electrostatic chuck 25 attracts and holds the wafer W by Coulomb force or Johnson-Rahbek force generated by a direct current voltage applied to the electrode plate 25c from the direct current power supply 26, and attracts and holds the edge ring ER by Coulomb force or Johnson-Rahbek force generated by a direct current voltage applied to the electrode plates 25d, 25e from the direct current power supplies 28, 29. That is, in a plan view of the electrostatic chuck 25, the electrode plate 25c is provided in a region inside the electrostatic chuck 25 overlapping at least a portion of the wafer W, and the electrode plates 25d, 25e are provided in regions inside the electrostatic chuck 25 overlapping at least a portion of the edge ring ER. Figure 1

[0033] As described above, the wafer W is placed on the upper surface of the center portion 25a of the electrostatic chuck 25, and the edge ring ER which ring-encloses the center portion 25a is placed on the upper surface of the outer peripheral portion 25b of the electrostatic chuck 25. That is, the edge ring ER is provided on the electrostatic chuck 25 in a manner of surrounding the periphery of the wafer W. Further, the lower surface of the electrostatic chuck 25 and the upper surface of the base 11 are in contact with each other. Therefore, the base 11 and the electrostatic chuck 25 are formed as a placement table which places the wafer W and the edge ring ER.

[0034] In the inside of the base 11, a ring-shaped refrigerant chamber 31 extending in the circumferential direction is provided. A refrigerant (for example, cooling water) of a prescribed temperature is circulated and supplied to the refrigerant chamber 31 from a cooling unit 32 via pipes 33, 34, and the processing temperature of the wafer W on the electrostatic chuck 25 is controlled by the temperature of the refrigerant.

[0035] ​Further, heat transfer gas (for example, He gas) from the heat transfer gas supply section 35 is supplied to between the upper surface of the electrostatic chuck 25 and the lower surface of the wafer W and between the upper surface of the electrostatic chuck 25 and the lower surface of the edge ring ER via the gas supply pipes 36 and the gas introduction holes 101, 102, 103. The gas supply pipes 36 are arranged in such a manner as to penetrate the base 11 and the base portion 25f of the electrostatic chuck 25. Further, the gas introduction holes 101, 102 connected to the gas supply pipes 36 are provided in the center portion 25a of the electrostatic chuck 25, and the gas introduction hole 103 connected to the gas supply pipe 36 is provided in the outer peripheral portion 25b of the electrostatic chuck 25. The two electrode plates 25d and 25e are arranged in the outer peripheral portion 25b of the electrostatic chuck 25 in such a manner that the electrode plate 25d and the electrode plate 25e are separated by the gas introduction hole 103. The heat transfer properties between the wafer W and the electrostatic chuck 25 and between the edge ring ER and the electrostatic chuck 25 are improved by the heat transfer gas supplied from the heat transfer gas supply section 35 via the gas supply pipes 36 and the gas introduction holes 101, 102, 103.

[0036] The shower head 24 of the top portion includes an electrode plate 37 having a large number of air holes 37a and an electrode support 38 that supports the electrode plate 37. Further, a buffer chamber 39 is provided in the inside of the electrode support 38, and a gas supply pipe 41 from a processing gas supply section 40 is connected to a gas introduction port 38a of the buffer chamber 39.

[0037] When a dry etching process is performed in the substrate processing apparatus 100, for example, first, the gate valve 20 is brought to an open state, the wafer W is carried into the chamber 10 and placed on the electrostatic chuck 25. Then, a mixed gas composed of C4F8 gas, O2 gas and argon Ar having a prescribed flow rate ratio is introduced as a processing gas into the chamber 10 at a prescribed flow rate and flow rate ratio from the processing gas supply section 40, and the pressure in the chamber 10 is brought to a prescribed value by the exhaust device 18. Further, the wafer W and the edge ring ER are electrostatically attracted to the electrostatic chuck 25 by applying a direct current voltage to the electrode plate 25c from the direct current power supply 26 and applying a direct current voltage to the electrode plates 25d, 25e from the direct current power supplies 28, 29. Then, a high frequency voltage is applied to the base 11 by the high frequency power supplies 21-1, 21-2. Thereby, the processing gas released from the shower head 24 is made into plasma, and the surface of the wafer W is etched by radicals and ions generated by the plasma.

[0038] <Positional relationship of electrostatic chuck, edge ring and wafer>

[0039] Figure 2 is a view showing one example of the positional relationship of the electrostatic chuck, the edge ring and the wafer.

[0040] As Figure 2As shown, the edge ring ER has a ring shape, and an inner peripheral portion 51 of the edge ring ER is formed thinner than an outer peripheral portion 52 of the edge ring ER. Also, an outer peripheral portion 25b of the electrostatic chuck 25 is formed thinner than a central portion 25a of the electrostatic chuck 25. The edge ring ER is placed on the outer peripheral portion 25b of the electrostatic chuck 25, and the wafer W is placed on the central portion 25a of the electrostatic chuck 25. In one example, the inner peripheral portion 51 of the edge ring ER is formed in such a manner that an upper surface of the inner peripheral portion 51 of the edge ring ER is lower than an upper surface of the central portion 25a of the electrostatic chuck 25. Also, in one example, the outer peripheral portion 52 of the edge ring ER is formed in such a manner that an upper surface of the outer peripheral portion 52 of the edge ring ER has substantially the same height as an upper surface of the wafer W or a height higher than the upper surface of the wafer W. Also, the wafer W has a disc shape, and a diameter of the wafer W is larger than a diameter of the central portion 25a of the electrostatic chuck 25. Therefore, when the wafer W is placed on the central portion 25a of the electrostatic chuck 25, a peripheral portion 61 of the wafer W protrudes outwardly of the central portion 25a of the electrostatic chuck 25, and a lower surface of the peripheral portion 61 of the wafer W and an upper surface of the inner peripheral portion 51 of the edge ring ER face each other.

[0041] Also, six gas introduction holes 101 and six gas introduction holes 102 are provided in the central portion 25a of the electrostatic chuck 25, and six gas introduction holes 103 are provided in the outer peripheral portion 25b of the electrostatic chuck 25. Therefore, the heat transfer gas is introduced between the upper surface of the central portion 25a of the electrostatic chuck 25 and the lower surface of the wafer W through the gas introduction holes 101 and 102, and is introduced between the upper surface of the outer peripheral portion 25b of the electrostatic chuck 25 and the lower surface of the outer peripheral portion 52 of the edge ring ER through the gas introduction holes 103.

[0042] <Structure of Edge Ring>

[0043] Figure 3 is a view showing an example of a structure of an edge ring. Figure 3 The edge ring ER1 shown in Figure 1 and Figure 2 is the edge ring ER.

[0044] In Figure 3 , the edge ring ER1 is formed by joining the ring-shaped member M1 and the ring-shaped member M2 with the adhesive layer B2. The member M1 is formed of a first material having plasma resistance, and the member M2 is formed of a second material having lower rigidity than the first material. In other words, the second material forming the member M2 is softer than the first material forming the member M1. As one example of the first material forming the member M1, silicon carbide, tungsten carbide (WC), magnesium oxide (MgO), or yttrium oxide (Y2O3) can be given. Also, as one example of the second material forming the member M2, silicon can be given.

[0045] The component M1 has a recess C1 in a lower surface S11 of the component M1, and the component M2 is arranged in the recess C1 of the component M1.

[0046] The thickness T2 of the component M2 is greater than the depth D1 of the recess C1, for example. In this case, the lower surface S21 of the component M2 protrudes toward the electrostatic chuck 25 side as compared with the lower surface S11 of the component M1, and therefore only the component M2 of the components M1 and M2 is in contact with the upper surface of the outer peripheral portion 25b of the electrostatic chuck 25. As a result, the adhesion of the edge ring ER1 to the electrostatic chuck 25 is further improved when the edge ring ER1 is electrostatically attracted to the electrostatic chuck 25.

[0047] The adhesive layer B2 is provided between the bottom surface U1 of the recess C1 and the upper surface S22 of the component M2. Further, a recess C2 having a depth of 40 μm, for example, is formed in the upper surface S22 of the component M2, and the adhesive layer B2 is provided in the recess C2 formed in the upper surface S22 of the component M2. The adhesive layer B2 contains an organic silicon-based adhesive, for example.

[0048] Further, the adhesive layer B2 can also contain a conductive filler. The thermal conductivity between the component M1 and the component M2 is improved because the adhesive layer B2 contains the conductive filler. As one example of the conductive filler, alumina can be given.

[0049] In the center portion 25a of the electrostatic chuck 25, annular seal bands SB11 and SB12 having convex shapes are formed, and the wafer W is supported on the center portion 25a by the seal bands SB11 and SB12. Therefore, a space SP1 corresponding to the heights of the seal bands SB11 and SB12 is formed between the upper surface of the center portion 25a and the lower surface of the wafer W. Since the space SP1 is connected to the gas introduction hole 102, the heat transfer gas supplied from the heat transfer gas supply portion 35 is introduced into the space SP1 through the gas introduction hole 102.

[0050] Further, in the outer peripheral portion 25b of the electrostatic chuck 25, annular seal bands SB21 and SB22 having convex shapes are formed, and the edge ring ER1 is supported on the outer peripheral portion 25b by the seal bands SB21 and SB22. Therefore, a space SP2 corresponding to the heights of the seal bands SB21 and SB22 is formed between the upper surface of the outer peripheral portion 25b and the lower surface S21 of the component M2. Since the space SP2 is connected to the gas introduction hole 103, the heat transfer gas supplied from the heat transfer gas supply portion 35 is introduced into the space SP2 through the gas introduction hole 103.

[0051] In the above-described embodiment, the case where the components M1 and M2 are joined by the adhesive layer B2 is exemplified, but the components M1 and M2 can be joined by diffusion joining.

[0052] As described above, the edge ring (edge ring ER1) of the present application includes: a ring-shaped first member (member M1) formed of a first material having plasma resistance; and a ring-shaped second member (member M2) formed of a second material having lower rigidity than the first material. The second member is arranged in a recess (recess C1) formed in a lower surface of the first member.

[0053] In the edge ring of the present application, since the first member exposed to plasma in plasma processing is formed of a first material having plasma resistance, the edge ring can be made to have plasma resistance. Also, since the second member in contact with the electrostatic chuck is formed of a second material having lower rigidity (i.e., softer) than the first material, the tightness between the edge ring and the electrostatic chuck can be improved. Therefore, by using the edge ring of the present application, the frequency of replacement of the edge ring can be reduced and the leakage of the heat transfer gas can be suppressed.

[0054] The edge ring and the substrate processing apparatus have been described above with the above-described embodiments, but the edge ring and the substrate processing apparatus of the present application are not limited to the above-described embodiments and various modifications and improvements can be made within the scope of the present application.

[0055] For example, the edge ring of the present application can be applied not only to a capacitively coupled plasma (CCP) apparatus but also to other substrate processing apparatuses. As the other substrate processing apparatuses, there can be an inductively coupled plasma (ICP) processing apparatus, a plasma processing apparatus using a radial line slot antenna, a helicon wave plasma (HWP) apparatus, an electron cyclotron resonance plasma (ECR) apparatus, and the like.

[0056] In addition, in the substrate processing apparatus 100 of the present embodiment, two electrode plates for electrostatic chucking are provided at the outer peripheral portion 25b of the electrostatic chuck 25, but the number of electrode plates provided at the outer peripheral portion 25b for electrostatic chucking can be one or more than three, for example.

[0057] In the present specification, a semiconductor substrate has been described as an object of plasma processing, but the object of plasma processing is not limited to a semiconductor substrate. The object of plasma processing can be various substrates for LCDs (liquid crystal displays), FPDs (flat panel displays), and the like, photomasks, CD substrates, printed circuit boards, and the like.

Claims

1. An edge ring characterized by: the edge ring is arranged so as to surround a periphery of a processed substrate placed on a stage, the edge ring has an area in which an electrode of the stage overlaps at least a part of the edge ring in plan view, the edge ring is electrostatically adsorbed by the electrode, the edge ring includes: a first member in a ring shape having a recess in a lower surface and formed of a first material having plasma resistance; and a second member in a ring shape arranged in the recess and formed of a second material having lower rigidity than the first material, the second member has a thickness greater than a depth of the recess so that a lower surface of the second member protrudes more toward the electrode side than a lower surface of the first member, whereby only the second member having lower rigidity of the first and second members is in contact with an upper surface of the stage.

2. The edge ring according to claim 1, characterized in that: the first material is silicon carbide, tungsten carbide, magnesium oxide, or yttrium oxide, the second material is silicon.

3. The edge ring according to claim 1, characterized in that: the first member and the second member are joined by means of an adhesive layer provided between a bottom surface of the recess and an upper surface of the second member.

4. The edge ring according to claim 3, characterized in that: the adhesive layer contains a silicone-based adhesive.

5. The edge ring according to claim 3 or 4, characterized in that: the adhesive layer further includes an electrically conductive filler.

6. The edge ring according to claim 3 or 4, characterized in that: the adhesive layer is provided in a recess formed in the upper surface of the second member.

7. A substrate processing apparatus characterized by comprising: including: a process container that provides a process space; a stage provided in the process container and capable of placing a processed substrate; and an edge ring arranged so as to surround a periphery of the processed substrate, the stage has an area in which an electrode electrostatically adsorbing the edge ring overlaps at least a part of the edge ring in plan view, the edge ring includes: a first member in a ring shape having a recess in a lower surface and formed of a first material having plasma resistance; and a second member in a ring shape arranged in the recess and formed of a second material having lower rigidity than the first material, and having a lower surface in contact with an upper surface of the stage, the second member has a thickness greater than a depth of the recess so that a lower surface of the second member protrudes more toward the electrode side than a lower surface of the first member, whereby only the second member having lower rigidity of the first and second members is in contact with an upper surface of the stage.

8. The substrate processing apparatus according to claim 7, characterized in that: there is further a space in which a heat transfer gas is supplied between the upper surface of the stage and the lower surface of the second member.

9. The substrate processing apparatus according to claim 8, characterized in that: the stage has an introduction hole that introduces the heat transfer gas into the space, the electrode is two electrodes arranged across the introduction hole. ​

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