A lower electrode assembly, its installation method and plasma processing device

Abstract

The present invention provides a lower electrode assembly, a mounting method thereof and a plasma processing device in which the lower electrode assembly is located. The gap between the dielectric ring and the base is divided into two or more gaps by cooperating with the dielectric ring and the base, and a protective ring is arranged between the dielectric ring and the base, and a protective layer is arranged on the outer side of the base, so as to avoid the plasma above the substrate and the focusing ring from leaking into the gap between the base and the edge ring assembly, prevent the plasma from corroding the base, reduce the possibility of arc discharge in the lower electrode assembly, and effectively ensure the safety of the use of the lower electrode assembly.

Description

Technical Field

[0001] The invention relates to the technical field of plasma etching, and in particular to the technical field of plasma processing for preventing a lower electrode assembly from generating an arc under high radio frequency power. Background Art

[0002] Micromachining of semiconductor substrates or substrates is a well-known technology that can be used to manufacture, for example, semiconductors, flat panel displays, light emitting diodes (LEDs), solar cells, etc. An important step in micromachining manufacturing is the plasma treatment process step, which is carried out inside a reaction chamber into which process gases are input. A radio frequency source is inductively and / or capacitively coupled to the interior of the reaction chamber to excite the process gas to form and maintain a plasma. Inside the reaction chamber, the exposed substrate is supported by a lower electrode assembly and fixed in a fixed position by a clamping force to ensure the safety of the substrate during the process and a high yield of the processing.

[0003] The lower electrode assembly includes not only an electrostatic chuck for fixing the substrate and a base for supporting the electrostatic chuck, but also an edge ring assembly arranged around the base. During the process of processing the substrate, the lower electrode assembly is used not only to support and fix the substrate, but also to control the temperature, electric field distribution, etc. of the substrate.

[0004] In the prior art, the commonly used material for the base is aluminum, and the material of the insert ring surrounding the periphery of the base is usually ceramic. Since the thermal expansion coefficients of the two are quite different, in order to ensure that the base operates within a larger temperature range, a certain space must be set between the insert ring and the base to accommodate the thermal expansion and contraction of the base.

[0005] As the processing precision of substrates becomes higher and higher, the RF power applied to the reaction chamber becomes larger and larger. High RF power can easily cause arc discharge in the narrow space of the reaction chamber, damaging the base and its peripheral components, and seriously threatening the stability and safety of the lower electrode assembly. Therefore, a solution is urgently needed to adapt to the ever-increasing RF application power and substrate processing uniformity requirements. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a lower electrode assembly for carrying a substrate to be processed, comprising:

[0007] A base, the base comprising a base body and a step portion extending outward from the base body;

[0008] an electrostatic chuck located above the susceptor; and

[0009] An edge ring assembly is disposed around the base and the electrostatic chuck, the edge ring assembly comprising:

[0010] a focusing ring disposed around the pedestal and / or electrostatic chuck, and

[0011] A dielectric ring is located below the focusing ring and surrounds the base. The dielectric ring includes a dielectric ring body and an extension portion extending from the dielectric ring body toward the base. A gap is provided between the dielectric ring and the base. The step portion cooperates with the extension portion to divide the gap into at least a first gap and a second gap.

[0012] Optionally, a protective layer is provided on the outer side of the base.

[0013] Optionally, the protective layer is an aluminum oxide polystyrene composite material.

[0014] Optionally, a protective ring is further arranged between the edge ring assembly and the base and / or the electrostatic chuck, and at least a portion of the protective ring abuts against the dielectric ring and the base.

[0015] Optionally, at least a portion of the protection ring abuts against the base and the electrostatic chuck.

[0016] Optionally, the protective ring is made of a plasma corrosion resistant material.

[0017] Optionally, the protective ring is made of polymer material.

[0018] Optionally, the protective ring is made of fluororubber or perfluororubber series.

[0019] Optionally, the protective ring is arranged above the step portion.

[0020] Optionally, the dielectric ring is made of high thermal conductivity ceramic material or aluminum oxide material.

[0021] Furthermore, the present invention also discloses a plasma processing device, including a vacuum reaction chamber, in which a lower electrode assembly is arranged, and the lower electrode assembly includes the features described above.

[0022] Furthermore, the present invention also discloses a method for installing a lower electrode assembly, comprising the following steps:

[0023] A pedestal with an electrostatic chuck is provided, wherein the pedestal comprises a pedestal body and a step portion extending outward from the pedestal body.

[0024] A dielectric ring is provided, the dielectric ring comprising a dielectric ring body and an extension portion extending toward a base, the extension portion of the dielectric ring is placed on a step portion of the base, a gap is provided between the dielectric ring and the base, the step portion cooperates with the extension portion to separate the gap into a first gap and a second gap;

[0025] A focusing ring is disposed above the dielectric ring.

[0026] Optionally, a protective layer is provided on the outer side of the base.

[0027] Optionally, a protective ring is disposed around the periphery of the electrostatic chuck and the pedestal, and the focusing ring at least partially covers the protective ring.

[0028] Optionally, the protection ring at least partially abuts against the base and the electrostatic chuck.

[0029] Optionally, the protective ring at least partially abuts against the dielectric ring.

[0030] The advantages of the present invention are as follows: the present invention provides a plasma-resistant lower electrode assembly and an installation method thereof, wherein the gap between the base and the dielectric ring is divided into a plurality of smaller gaps by the matching arrangement of the base and the dielectric ring, thereby preventing the plasma above the substrate and the focusing ring from leaking into the gap between the base and the edge ring assembly, while reducing the size of a single gap and reducing the possibility of arc discharge that may occur in the lower electrode assembly, thereby effectively ensuring the safety of the use of the lower electrode assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic structural diagram of a capacitively coupled plasma processing device is shown;

[0033] Figure 2 A schematic diagram of a local lower electrode assembly structure is shown;

[0034] Figure 3 A schematic diagram showing the structure of a partial lower electrode assembly of another embodiment;

[0035] Figure 4 A schematic structural diagram of an inductively coupled plasma processing device is shown. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Figure 1 A schematic diagram of a capacitively coupled plasma processing device is shown, including a vacuumable reaction chamber 100 surrounded by an outer wall 10. The reaction chamber 100 is used to process a substrate 103. The reaction chamber includes a lower electrode assembly for supporting the substrate while controlling the substrate temperature, electric field and other factors affecting the substrate processing. The lower electrode assembly includes a base 101 for carrying an electrostatic chuck 102. The base 101 is provided with a temperature control device for controlling the temperature of the upper substrate. The electrostatic chuck 102 is used to carry the substrate 103. A DC electrode is provided inside the electrostatic chuck, and DC adsorption is generated between the back of the substrate and the bearing surface of the electrostatic chuck through the DC electrode to fix the substrate. An edge ring assembly 20 is provided around the base and the periphery of the electrostatic chuck to adjust the temperature and electric field distribution of the edge area of ​​the substrate. A plasma confinement ring 108 is arranged around the edge ring assembly 20, and is located between the edge ring assembly 20 and the side wall of the reaction chamber, and is used to confine the plasma to the reaction area while allowing the gas to pass through; a grounding ring 109 is located below the plasma confinement ring, and is used to provide electric field shielding to prevent plasma leakage. A bias RF power supply usually applies a bias RF signal to the lower electrode assembly to control the bombardment direction of the plasma. The lower electrode assembly disclosed in the present invention can be used for example Figure 1 The capacitively coupled plasma processing apparatus shown.

[0038] exist Figure 1 In the capacitively coupled plasma processing apparatus shown, in addition to the lower electrode assembly, an upper electrode assembly is also included, and the upper electrode assembly includes a gas shower head 30 for introducing the process gas in the gas supply device into the reaction chamber. A high-frequency radio frequency power source applies a high-frequency radio frequency signal to at least one of the upper electrode assembly or the lower electrode assembly to form a radio frequency electric field between the upper electrode assembly and the lower electrode assembly, and excites the process gas in the reaction chamber into plasma, so as to achieve plasma processing of the substrate to be processed.

[0039] Figure 2A schematic diagram of a local lower electrode assembly structure is shown. In the structure shown in the figure, the lower electrode assembly includes: a focus ring 201, which is arranged around the pedestal 101 and / or the electrostatic chuck 102 and the substrate 103, and is used to adjust the temperature and electric field distribution of the edge area of ​​the substrate 103; a dielectric ring 202 is arranged below the focus ring 201, and the dielectric ring 202 is used to maintain the potential difference between the focus ring 201 and the pedestal 101, and adjust the temperature of the focus ring 201. A protective ring 104 is sleeved between the pedestal 101 and the dielectric ring 202, and the protective ring 104 is made of a plasma corrosion resistant material, which is usually a polymer material such as fluororubber or perfluororubber series.

[0040] In the present invention, the material of the base 101 is usually a conductive metal material, such as aluminum, and the dielectric ring 202 surrounding the base is usually a ceramic material, preferably a high thermal conductivity ceramic material, which can also be an Al2O3 material. Since the thermal expansion coefficients of the base 101 and the dielectric ring 202 are different, in order to avoid the components from being extruded by heat, a certain gap needs to be set between the dielectric ring 202 and the base 101 during installation. As the processing accuracy of the substrate becomes higher and higher, the RF power applied to the reaction chamber becomes larger and larger. High RF power can easily generate arc discharge in the narrow space in the reaction chamber, damage the base and its peripheral components, and seriously threaten the stability and safety of the lower electrode assembly.

[0041] In this embodiment, the base 101 includes a base body 1011 and a step portion 1012 extending outward from the base body 1011, and the dielectric ring 202 includes a dielectric ring body 2021 and an extension portion 2022 extending from the dielectric ring body 2021 to the base 101. The step portion 1012 cooperates with the extension portion 2022, and the extension portion 2022 of the dielectric ring 202 can be in close contact with the step portion 1012 of the base 101 through the gravity of the dielectric ring 202 itself or the pressure applied from the outside, so that the gap between the base 101 and the dielectric ring 202 is divided into a first gap 1051 and a second gap 1052. The protective ring 104 is disposed in the first gap 1051, and the protective ring 104 surrounds the base 101 and the periphery of the electrostatic chuck, and at least partially abuts against the dielectric ring 202. It can prevent plasma from bombarding the connection layer between the electrostatic chuck and the base 101, and can further prevent plasma from entering the second gap 1052, thereby reducing the possibility of arc discharge. According to the principle of arc discharge, under the premise of the same gas pressure and applied electric field, the larger the gas diffusion space, the easier it is to produce arc discharge. The gap is divided into two smaller ones by the step portion 1012 and the extension portion 2022, which reduces the gas diffusion space, thereby effectively reducing the probability of arc discharge and improving the safe voltage operating range of the lower electrode assembly. At the same time, a part of the protective ring 104 is located between the base 101 and the focusing ring 201, so that the base 101 and the focusing ring 201 are electrically isolated. At the same time, the protective ring 104 is used to prevent plasma from entering the first gap 1051 through the gap between the focusing ring and the base or the electrostatic chuck. Furthermore, a protective layer 106 is provided on the outer side of the base 101, which is a plasma corrosion-resistant material, usually an aluminum oxide material, but can also be an yttrium oxide material, which can prevent the leaked plasma from corroding the base 101, further improving the safety of the lower electrode assembly.

[0042] The shape of the protection ring 104 can be varied. Figure 2 In the embodiment shown, the guard ring 104 extends in the direction of the first gap 1051, and the extension portion 2022 of the dielectric ring abuts against a portion of the guard ring to prevent gas from entering the second gap 1052 and avoid arc discharge in the second gap. In other embodiments, the guard ring, the focus ring, and the dielectric ring may have other matching shapes.

[0043] Figure 3A schematic diagram of the lower electrode assembly of another embodiment is shown. For the sake of clarity and brevity, the same reference numerals are used to describe the same parts as above. In this embodiment, the base 101 includes at least two step portions 1013 and 1014, and the extension of the dielectric ring 202 toward the base is in close contact with at least one step portion, dividing the gap between the dielectric ring and the base into two or more, so as to further prevent the gas from entering the gap below. In this embodiment, the extension of the focusing ring 201 toward the base at least partially abuts against the upper surface of the protective ring 104, so as to achieve the gas path blocking of the gap between the focusing ring and the base, and prevent the gas from entering the gap below to generate arc discharge.

[0044] Optionally, a heat conduction layer is provided between the focus ring 201 and the dielectric ring 202, and / or a heat conduction layer is provided between the dielectric ring 202 and the base 101, so as to improve the conduction capability of the temperature of the focus ring 201. In other embodiments, the dielectric ring 201 may also be provided above other supporting components capable of independent temperature control, so as to realize independent temperature control of the focus ring 201 different from that of the substrate 103.

[0045] Optionally, the present invention further provides a method for installing a lower electrode assembly, comprising the following steps:

[0046] A base 101 with an electrostatic chuck 102 is provided, wherein the base 101 includes a base body 1011 and a step portion 1012 extending outward from the base body 1011.

[0047] A dielectric ring 202 is provided, the dielectric ring 202 comprises a dielectric ring body 2021 and an extension portion 2022 extending from the dielectric ring body 2021 toward the base 101. A gap is provided between the dielectric ring 202 and the base 101. The extension portion of the dielectric ring is placed on the step portion of the base, and a downward pressure can be selectively applied to the dielectric ring 202 to further improve the tightness between the extension portion 2022 and the step portion 1012. The step portion 1012 cooperates with the extension portion 2022 to separate the gap into a first gap 1051 and a second gap 1052. A protective ring 104 is placed in the first gap. The protective ring 104 is a plasma corrosion resistant material, which is usually a polymer material such as fluororubber or perfluororubber series. The protective ring 104 can also be firstly surrounded by a dielectric ring and arranged around the base and the electrostatic chuck, and then the dielectric ring 202 is arranged around the base and the protective ring. A focusing ring 201 is disposed above the dielectric ring 202 and the guard ring 104 , and the focusing ring at least partially covers the guard ring to prevent gas from entering the gap between the dielectric ring and the susceptor.

[0048] The lower electrode assembly described above can also be used as Figure 4In the inductively coupled plasma plasma processing device shown, in this embodiment, the lower electrode assembly has the structure as described above, which will not be repeated here. In addition, an insulating window 130 is arranged above the reaction chamber, and an inductor 140 is arranged above the insulating window. A high-frequency RF power supply 145 applies a RF signal to the inductor 140, and the inductor 140 generates an alternating magnetic field, which induces an alternating electric field in the reaction chamber to achieve plasma dissociation of the process gas entering the reaction chamber. In this embodiment, the process gas can be injected into the reaction chamber from the side wall of the reaction chamber, and a gas injection port can also be set on the insulating window to accommodate the entry of the process gas. The bias RF power is applied to the lower electrode assembly through a bias RF matching to control the energy distribution of the plasma.

[0049] The present invention divides the gap between the dielectric ring and the base into two smaller gaps by cooperating with the dielectric ring and the base, and arranges a protective ring between the dielectric ring and the base, and arranges a protective layer on the outer side of the base, thereby preventing the plasma above the substrate and the focusing ring from leaking into the gap between the base and the edge ring assembly, preventing the plasma from corroding the base, reducing the possibility of arc discharge that may occur in the lower electrode assembly, and effectively ensuring the safety of the use of the lower electrode assembly.

[0050] The lower electrode assembly disclosed in the present invention is not limited to being applied to the plasma processing devices of the above two embodiments, but can also be applied to other plasma processing devices, which will not be described in detail here.

[0051] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A lower electrode assembly for carrying a substrate to be processed, characterized in that: It includes: A base, the base comprising a base body and a step portion extending outward from the base body; an electrostatic chuck located above the susceptor; and An edge ring assembly is disposed around the base and the electrostatic chuck, the edge ring assembly comprising: a focusing ring disposed around the pedestal and / or electrostatic chuck, and A dielectric ring, which is located below the focusing ring and is arranged around the base, the dielectric ring comprises a dielectric ring body and an extension portion extending from the dielectric ring body toward the base, a gap is provided between the dielectric ring and the base, and the step portion cooperates with the extension portion to divide the gap into at least a first gap and a second gap; A guard ring is further disposed between the edge ring assembly and the pedestal and / or the electrostatic chuck, at least a portion of which abuts against the pedestal and the electrostatic chuck, and at least a portion of which abuts against the dielectric ring.

2. The lower electrode assembly according to claim 1, characterized in that: A protective layer is arranged on the outer side of the base.

3. The lower electrode assembly according to claim 2, characterized in that: The protective layer is an aluminum oxide and / or yttrium oxide material layer.

4. The lower electrode assembly according to claim 1, wherein: The protection ring is made of a plasma corrosion resistant material.

5. The lower electrode assembly according to claim 1, wherein: The protective ring is made of polymer material.

6. The lower electrode assembly according to claim 1, wherein: The protective ring is made of fluororubber or perfluororubber series.

7. The lower electrode assembly according to claim 1, wherein: The protection ring is disposed above the step portion.

8. The lower electrode assembly according to claim 1, wherein: The focus ring includes an extension portion extending toward the electrostatic chuck, and the extension portion at least partially covers the protection ring.

9. The lower electrode assembly according to claim 1, wherein: The dielectric ring is made of high thermal conductivity ceramic material or aluminum oxide material.

10. A plasma processing apparatus comprising a vacuum processing chamber, characterized in that: The vacuum processing chamber comprises the lower electrode assembly as claimed in any one of claims 1 to 9.

11. A method for installing a lower electrode assembly, comprising the following steps: A pedestal with an electrostatic chuck is provided, wherein the pedestal comprises a pedestal body and a step portion extending outward from the pedestal body. A protective ring is disposed around the periphery of the electrostatic chuck and the pedestal, and the protective ring at least partially abuts against the pedestal and the electrostatic chuck; A dielectric ring is provided, the dielectric ring comprising a dielectric ring body and an extension portion extending toward a base, the extension portion of the dielectric ring is placed on a step portion of the base, a gap is provided between the dielectric ring and the base, the step portion cooperates with the extension portion to separate the gap into a first gap and a second gap; at least a portion of the protective ring abuts against the dielectric ring; A focusing ring is disposed above the dielectric ring.

12. The installation method according to claim 11, characterized in that: A protective layer is arranged on the outer side of the base.

13. The installation method according to claim 11, characterized in that: The focus ring at least partially covers the guard ring.

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