Lifting ring assembly and plasma processing device

Abstract

The invention discloses a lifting ring assembly and a plasma processing device, and the lifting ring assembly comprises a lifting ring which is arranged in a reaction cavity of the plasma processing device in a lifting manner; the adjusting module is arranged outside the reaction cavity and used for adjusting the potential of the lifting ring, one end of the adjusting module is connected with the lifting ring, and the other end of the adjusting module is grounded. The polymer is not easy to deposit on the surface of the lifting ring in the etching process, and the cleaning strength of the lifting ring in the cleaning process can be improved, so that the deposition of the polymer on the surface of the lifting ring is reduced.

Description

Technical Field

[0001] This invention relates to the field of semiconductor devices, and more specifically to a lifting ring assembly and a plasma processing device. Background Technology

[0002] In plasma processing equipment, lifting rings can be used to confine plasma during the process by lowering them in conjunction with confinement rings, and to raise them during wafer transfer. However, during high aspect ratio etching, inorganic materials and etching byproducts form polymer deposits on the chamber walls, particularly on the surfaces of components at lower temperatures, such as the lifting rings. These polymers are relatively stable sheet-like materials, and during cleaning of the reaction chamber, the radio frequency field is mainly concentrated between the upper and lower electrodes, while the lifting ring surface, located at the edge, receives almost no ion bombardment and is difficult to clean. This results in the polymer on the lifting ring surface being difficult to remove completely, leading to long-term accumulation that affects the stability of the etching process, and consequently, the process effect and quality.

[0003] In existing technologies, such as Chinese patents CN106920726B, CN106611691B, and CN106548914B, a common approach is to place radio frequency electrodes inside the lifting ring to introduce radio frequency during the process or cleaning, thereby creating an additional plasma region in the lifting ring for bombardment cleaning. However, this method requires additional radio frequency power, increasing equipment cost and power consumption. Furthermore, because the lifting ring is adjacent to the constraint ring and the upper electrode, the introduction of radio frequency power poses a risk of arcing. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a lifting ring assembly that makes it difficult for polymers generated during the etching process to deposit on the lifting ring, and to enhance the cleaning ability of polymers on the surface of the lifting ring.

[0005] To achieve the above objectives, the present invention discloses a lifting ring assembly for a plasma processing device, comprising:

[0006] A lifting ring is movably mounted within the reaction chamber of the plasma processing device;

[0007] An adjustment module is located outside the reaction chamber and is used to adjust the potential of the lifting ring. One end of the adjustment module is connected to the lifting ring, and the other end is grounded.

[0008] Optionally, the adjustment module includes a variable capacitor, one end of which is connected to the lifting ring and the other end is grounded.

[0009] Optionally, the adjustment module further includes a switch, one end of which is grounded and connected in parallel with the variable capacitor.

[0010] Optionally, the lifting ring is a semiconductor.

[0011] Optionally, the resistance of the lifting ring is in the kiloohm range.

[0012] Optionally, the lifting ring is made of silicon.

[0013] Optionally, the lifting ring assembly further includes a conductive layer that covers the surface of the lifting ring and is electrically connected to the adjustment module.

[0014] Optionally, the conductive layer is a graphite layer or a metal layer.

[0015] Optionally, the lifting ring is electrically connected to the adjustment module via multiple wires, which are distributed on the surface of the lifting ring.

[0016] The present invention also discloses a plasma processing apparatus, comprising:

[0017] reaction chamber;

[0018] The base is located at the bottom of the reaction chamber;

[0019] A gas spray head is disposed at the top of the reaction chamber, opposite to the base;

[0020] The lifting ring assembly is disposed inside the reaction chamber, surrounds the gas spray head, and can move up and down in the vertical direction.

[0021] Optionally, the potential difference between the base and the lifting ring can be adjusted by the adjustment module in the lifting ring assembly.

[0022] Compared with the prior art, the technical solution of the present invention has at least the following advantages and beneficial effects:

[0023] The proposed lifting ring assembly includes a lifting ring that can be raised and lowered inside the reaction chamber and an adjustment module that is located outside the reaction chamber. The adjustment module is electrically connected to the lifting ring and can adjust the potential of the lifting ring, thereby adjusting the potential difference between the lifting ring and the lower electrode, and thus adjusting the bombardment intensity of the plasma on the lifting ring. This not only makes it difficult for polymers to be deposited on the surface of the lifting ring during the etching process, but also improves the cleaning intensity of the lifting ring, thereby reducing polymer deposition on the surface of the lifting ring.

[0024] By adjusting the potential of the lifting ring, plasma can reach the surface of the dead cleaning zone of the lifting ring for cleaning, thereby improving the cleanliness of the lifting ring.

[0025] At the same time, since no additional radio frequency power supply is required, the equipment cost and power consumption are reduced, and the risk of arc discharge is also reduced. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the reaction chamber of a plasma processing device;

[0027] Figure 2 This is a schematic diagram of the reaction chamber of a plasma processing device according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the reaction chamber of a plasma processing device according to another embodiment of the present invention. Detailed Implementation

[0029] The following will be combined with the embodiments of the present invention. Figures 1 to 3 The technical solutions, structural features, objectives and effects achieved in the embodiments of the present invention will be described in detail.

[0030] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0031] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0032] like Figure 1The diagram shows a reaction chamber 10 of a plasma processing apparatus. The reaction chamber 10 includes a cylindrical sidewall 14 with a wafer transfer port 13 for the wafer W to enter and exit the reaction chamber 10. A gas spray head 11 and a base 15 opposite to the gas spray head 11 are disposed within the reaction chamber 10. The gas spray head 11 is located above the reaction chamber 10 and connected to a gas supply device for supplying reactive gas into the reaction chamber 10. The gas spray head 11 also serves as the upper electrode, and the base 15 serves as the lower electrode. The area between the upper and lower electrodes is the reaction region. At least one radio frequency power supply is applied to the upper or lower electrode, generating a radio frequency electric field between the upper and lower electrodes, ionizing the reactive gas to form plasma, which is then used to perform an etching process on the wafer W. The presence of the transfer port 13 affects the uniformity of the radio frequency electric field within the reaction chamber 10. Therefore, a lifting ring 12 is provided between the gas spray head 11 and the base 15. This lifting ring 12 is close to the side wall 14, surrounds the gas spray head 11, and can move vertically up and down to expose or block the transfer port 13. This lifting ring 12 improves the uniformity of the radio frequency electric field. During the process, the lifting ring 12 is lowered to confine the plasma in conjunction with the confinement ring, while during the transfer process, the lifting ring 12 can be raised to transfer the wafer.

[0033] However, due to the application of inorganic fluorides in the etching process, etching byproducts easily form polymer deposits on the surfaces of cavity components, especially on components with lower temperatures, such as the surface of the lifting ring 12. Furthermore, during cavity cleaning, because the radio frequency electric field is mainly concentrated between the upper and lower electrodes, the surface of the lifting ring 12 receives almost no ion bombardment, making it difficult to achieve a good cleaning effect. Additionally, the lifting ring 12 has some hard-to-reach corners, i.e., cleaning dead zones, where cleaning ions rarely reach. Therefore, the polymer on the surface of the lifting ring 12 is difficult to clean completely, and long-term accumulation can affect the stability of the etching process.

[0034] This invention proposes a lifting ring assembly and a plasma treatment device. The lifting ring assembly includes a lifting ring 22 disposed within a reaction chamber 20 and an adjustment module 27 disposed outside the reaction chamber. The adjustment module 27 is electrically connected to the lifting ring 22 and can adjust the potential of the lifting ring 22. By adjusting the potential of the lifting ring 22 during the etching and cleaning processes, the potential difference between the lifting ring 22 and the lower electrode is controlled. This not only makes it less likely for polymers to deposit on the surface of the lifting ring 22 during the etching process but also increases the cleaning intensity of the lifting ring 22 during the cleaning process, thereby reducing polymer deposition on the surface of the lifting ring 22. Simultaneously, since no additional radio frequency power supply is required, the equipment cost and power consumption are reduced, and the risk of arc discharge is lowered.

[0035] To better understand the technical solution and effects of this application, the specific embodiments will be described in detail below with reference to the accompanying drawings.

[0036] like Figure 2 As shown, a reaction chamber 20 of a plasma processing apparatus according to an embodiment of the present invention has a wafer transfer port 23 on its side wall 24 for allowing a wafer W to enter and exit the reaction chamber 20. A base 25 is located at the bottom of the reaction chamber 20 to support the wafer W for processing and also serves as the lower electrode of the reaction chamber 20. A gas spray head 21 is located at the top of the reaction chamber 20, connected to an external gas supply device to deliver reaction gas into the reaction chamber 20 and also serving as the upper electrode of the reaction chamber 20. The upper and lower electrodes are arranged opposite each other, with the area between them being the reaction region. At least one radio frequency power supply is applied to the upper or lower electrode through a matching network to generate a radio frequency electric field in the reaction region, dissociating the reaction gas into plasma for etching the wafer W. A plasma confinement ring 26 is arranged around the base 25, with an exhaust channel on the plasma confinement ring 26. The reaction gas can be discharged from the reaction chamber through the exhaust channel, while the exhaust channel confines the plasma within the reaction region to prevent plasma leakage.

[0037] The plasma processing device also includes a lifting ring assembly, which includes a lifting ring 22 that can be raised and lowered inside the reaction chamber 20 and an adjustment module 27 that is located outside the reaction chamber 20.

[0038] In one embodiment, the riser ring 22 is a semiconductor with a resistance in the kiloohm range, which is significantly lower than the resistance of current megaohm-level riser rings and can improve its conductivity.

[0039] The lifting ring 22 surrounds the gas spray head 21 and can move vertically up and down. When wafer W needs to be transferred, the lifting ring 22 moves upward, exposing the wafer transfer port 23. When processing is required, the lifting ring 22 moves downward, blocking the wafer transfer port 23, and the lower end of the lifting ring 22 connects with the plasma confinement ring 26 to confine the plasma region. The lifting ring 22 solves the problem of uneven RF electric field distribution caused by the wafer transfer port 23.

[0040] One end of the adjustment module 27 is connected to the lifting ring 22, and the other end is grounded. The adjustment module 27 can adjust the potential of the lifting ring 22, thereby adjusting the potential difference between the lifting ring 22 and the base 25, and thus adjusting the thickness of the plasma sheath and the electric field strength to change the bombardment intensity of the plasma on the surface of the lifting ring 22.

[0041] During the process, the potential of the lifting ring 22 is adjusted to reduce the probability of polymer adhering to its surface. During the cleaning process, the potential of the lifting ring 22 is adjusted to increase the cleaning intensity of the plasma on the polymer surface, thereby minimizing polymer deposition on the lifting ring 22. Furthermore, by directly adjusting the potential of the lifting ring 22, the plasma can reach the cleaning dead zone on the surface of the lifting ring 22 to clean the adhering polymer.

[0042] When the reactant gas forms plasma under the influence of a radio frequency electric field, electrons, being much smaller in mass than ions, move faster in the electric field. Therefore, electrons reach the surface of the lifting ring 22 first, while ions lag behind, forming a plasma sheath near the surface of the lifting ring 22. The electron concentration within the sheath is low, while the ion concentration is high. The surface of the lifting ring 22 absorbs electrons and becomes negatively charged, attracting surrounding positive ions. This creates an electric field pointing towards the surface of the lifting ring 22 within the sheath. This electric field accelerates the movement of positive ions in the plasma towards the surface of the lifting ring 22. The accelerated positive ions bombard the polymer on the surface of the lifting ring 22 with higher energy, thus cleaning the polymer. When the potential difference between the lifting ring 22 and the base 25 is changed, the sheath thickness and the electric field strength within the sheath change accordingly. The ions in the sheath acquire different energies, resulting in varying bombardment intensities on the surface of the lifting ring 22.

[0043] During the cleaning process, when it is necessary to increase the cleaning intensity on the surface of the lifting ring 22, the potential of the lifting ring 22 is changed by adjusting the module 27 to increase the potential difference between the lifting ring 22 and the base 25; when it is necessary to decrease the cleaning intensity on the surface of the lifting ring 22, the potential of the lifting ring 22 is changed by adjusting the module 27 to decrease the potential difference between the lifting ring 22 and the base 25.

[0044] Considering that the lifting ring 22 surrounds the gas spray head 21, controlling the potential difference between the lifting ring 22 and the gas spray head 21 during the etching process can, to some extent, change the deposition position of the polymer. If the potential of the lifting ring 22 is adjusted to be the same as that of the gas spray head 21, the bombardment intensity of ions on the lifting ring 22 is lower, resulting in more polymer adhering to the surface of the lifting ring 22. If the potential of the lifting ring 22 is adjusted to zero, i.e., ground potential, the bombardment intensity of ions on the lifting ring 22 is increased, resulting in more polymer adhering to the gas spray head 21. Therefore, in practical applications, the potential of the lifting ring 22 should be adjusted according to the actual situation and requirements. The specific potential selection can be determined through a combination of calculation and experimentation.

[0045] In one embodiment, the adjustment module 27 includes a variable capacitor C1, one end of which is connected to the lifting ring 22 and the other end is grounded. The variable capacitor C1 adjusts the potential of the lifting ring 22, thereby adjusting the potential difference between the lifting ring 22 and the lower electrode, and thus adjusting the bombardment intensity of the lifting ring 22 by ions. Therefore, the potential of the lifting ring 22 can be adjusted by the adjustment module 27, which is composed of passive components, further reducing power consumption and the risk of arc discharge.

[0046] Furthermore, since the variable capacitor C1 is insufficient to bring the potential of the lifting ring 22 to ground potential, a switch K1 is connected in parallel with the variable capacitor C1. One end of the switch K1 is grounded, and the other end is directly connected to the lifting ring 22. When it is necessary to maximize the potential difference between the lifting ring 22 and the base 25, the switch K1 is closed, directly grounding the lifting ring 22. When it is necessary to reduce the potential difference between the lifting ring 22 and the base 25 or to adjust the potential difference, the switch K1 is opened, grounding the lifting ring 22 through the variable capacitor C1. The potential of the lifting ring 22 can then be adjusted by regulating the value of the variable capacitor C1.

[0047] In another embodiment, such as Figure 3 As shown, the lifting ring 22 is made of silicon. Due to the poor conductivity of silicon, it is difficult to achieve uniform grounding of the lifting ring 22. Furthermore, using only a single wire to connect the lifting ring 22 and the adjustment module 27 would result in excessive current being carried by the wire, posing a risk of burnout. Therefore, a conductive layer 28 is provided. This conductive layer 28 covers the upper and outer surfaces of the lifting ring 22 and is electrically connected to the adjustment module 27. The conductive layer 28 can be a graphite layer or a metal layer, for example, an aluminum tape or a copper tape.

[0048] Preferably, the portion of the upper surface of the lifting ring 22 adjacent to the gas spray head 21 and the portion of the outer surface of the lifting ring 22 adjacent to the plasma confinement ring 26 are not provided with a conductive layer 28, so as to prevent arc discharge between the lifting ring 22 and the gas spray head 21 or the plasma confinement ring 26, which could damage the reaction chamber 20.

[0049] In addition, the silicon-made lifting ring 22 will also oxidize during actual use, generating a silicon oxide layer as a corrosion-resistant coating, thereby improving the service life of the lifting ring 22.

[0050] In another embodiment, multiple wires are connected to the surface of the lifting ring 22, so that the lifting ring 22 is electrically connected to the adjustment module 27 through the multiple wires. The multiple wires are distributed on the upper surface and outer surface of the lifting ring 22, which can not only disperse the current to avoid burning the wires, but also make the lifting ring 22 evenly grounded, thereby improving the potential uniformity of the lifting ring 22.

[0051] This invention achieves passive adjustment of the potential of the lifting ring 22 through the adjustment module 27, without the need for an external power supply. While maintaining the cleanliness of the surface of the lifting ring 22, it saves equipment costs and reduces energy consumption, which is conducive to energy conservation, emission reduction and environmental friendliness.

[0052] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A lifting ring assembly for a plasma processing device, characterized in that, include: A lifting ring is movably mounted within the reaction chamber of the plasma processing device; An adjustment module is located outside the reaction chamber and is used to adjust the potential of the lifting ring. One end of the adjustment module is connected to the lifting ring, and the other end is grounded.

2. The lifting ring assembly as described in claim 1, characterized in that, The adjustment module includes a variable capacitor, one end of which is connected to the lifting ring, and the other end is grounded.

3. The lifting ring assembly as described in claim 2, characterized in that, The adjustment module also includes a switch, one end of which is grounded and connected in parallel with the variable capacitor.

4. The lifting ring assembly as described in claim 1, characterized in that, The lifting ring is a semiconductor.

5. The lifting ring assembly as described in claim 4, characterized in that, The resistance of the lifting ring is in the kiloohm range.

6. The lifting ring assembly as described in claim 4, characterized in that, The lifting ring is made of silicon.

7. The lifting ring assembly as described in claim 6, characterized in that, The lifting ring assembly also includes a conductive layer that covers the surface of the lifting ring and is electrically connected to the adjustment module.

8. The lifting ring assembly as described in claim 7, characterized in that, The conductive layer is a graphite layer or a metal layer.

9. The lifting ring assembly as described in claim 4, characterized in that, The lifting ring is electrically connected to the adjustment module via multiple wires, which are distributed on the surface of the lifting ring.

10. A plasma processing apparatus, characterized in that, include: reaction chamber; The base is located at the bottom of the reaction chamber; A gas spray head is disposed at the top of the reaction chamber, opposite to the base; The lifting ring assembly as described in any one of claims 1-9 is disposed within the reaction chamber, surrounds the gas spray head, and can move up and down in the vertical direction.

11. The plasma processing apparatus as claimed in claim 10, characterized in that, The potential difference between the base and the lifting ring is adjusted by the adjustment module in the lifting ring assembly.

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