A lower electrode assembly and plasma processing apparatus

Abstract

The utility model discloses a lower electrode subassembly and plasma processing device, lower electrode subassembly includes: pedestal for carrying wafer, focus ring is set up on the pedestal and is set around the wafer, and the top outer edge of focus ring is equipped with the fillet transition, and the radius of fillet is greater than or equal to 0.4mm. The utility model can reduce the probability of arc discharge at the top outer edge of focus ring and the accidental fragmentation of the top outer edge of focus ring due to the excessively high local temperature.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor processing equipment technology, and in particular to a lower electrode assembly and plasma processing equipment. Background Technology

[0002] Plasma processing equipment is used to process materials such as wafers. Examples of wafer processing include deposition, ashing, etching, cleaning, and / or other processes.

[0003] During the etching process of a wafer, a focusing ring needs to be placed around the periphery of the electrostatic chuck in the lower electrode assembly to ensure the uniformity and consistency of etching at the wafer edge. By coupling a portion of the radio frequency energy, the focusing ring can induce the formation of a uniformly distributed plasma sheath at the wafer edge. This sheath has a significant effect on improving the etching uniformity at the substrate edge.

[0004] Around the focusing ring, a cover ring is usually installed. Its main function is to protect the focusing ring and the components below it from damage caused by plasma or ions during the etching process.

[0005] like Figure 1 As shown in (a), in the newly installed focusing ring F and covering ring C combination, the plasma sheath P1 at the outermost edge of the focusing ring F changes relatively gently. This gentle distribution of the plasma sheath P1 means that the bombardment intensity of the ions on the edge F1 of the focusing ring F is comparable to the bombardment intensity on the upper surface of the focusing ring F, and no significant enhancement phenomenon is observed. Therefore, in the initial stage of use, the edge portion of the focusing ring F can maintain good stability and integrity.

[0006] However, as Figure 1 As shown in (b), with the continuous etching process and the gradual accumulation of usage time, the upper surface of the cover ring C near the focusing ring F gradually thins due to the continuous etching effect. This change results in more and more of the outer edge of the focusing ring F being exposed, which in turn affects the distribution of the plasma sheath P1. When the inner edge C1 of the cover ring C wears down to a certain extent, the plasma sheath P1 at the outer edge of the focusing ring F will be significantly bent, forming an electric field distribution similar to a tip discharge. This change in electric field distribution not only enhances the local electric field strength but also easily leads to the occurrence of arcing.

[0007] Furthermore, due to the increased local electric field strength, the bombardment of ions at the outer edge F1 of the focusing ring F becomes more intense. This intense bombardment can lead to excessively high local temperatures at the outer edge of the focusing ring F, resulting in thermal stress concentration and accidental fracture of the focusing ring F material. Damage to the focusing ring F not only affects the stability and uniformity of the etching process but may also lead to downtime and increased costs for the entire etching equipment.

[0008] The statements herein provide only background information relating to this invention and do not necessarily constitute prior art. Utility Model Content

[0009] This invention provides a lower electrode assembly and plasma processing equipment to avoid accidental arc discharge and possible breakage of the focusing ring edge.

[0010] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0011] A lower electrode assembly includes: a base for supporting a wafer; a focusing ring disposed on the base and surrounding the wafer; the top outer edge of the focusing ring has a rounded transition, the radius of which is greater than or equal to 0.4 mm.

[0012] Optionally, the radius of the fillet is in the range of 0.4 mm to 1 mm.

[0013] Optionally, the rounded corner is provided with a chamfer.

[0014] Optionally, the two ends of the chamfer are transitioned with sub-rounded corners.

[0015] Optionally, the radius of the sub-rounded corner is in the range of 1mm to 2mm.

[0016] Optionally, it also includes a cover ring, which is disposed around the focusing ring and mounted on the edge of the base.

[0017] Optionally, the upper surface of the cover ring is not lower than the upper surface of the focusing ring.

[0018] Optionally, the height difference between the upper surface of the cover ring and the upper surface of the focusing ring is 0.5 mm to 1.5 mm.

[0019] Optionally, a step is provided on the outer periphery of the focusing ring, and the upper surface of the focusing ring is higher than the top surface of the step; the radial cross-section of the covering ring is L-shaped, including a horizontal extension section and a vertical extension section, the inner side of the horizontal extension section covers the top surface of the step, and the vertical extension section covers part of the sidewall of the base.

[0020] Optionally, there is a distance h between the upper surface of the focusing ring and the top surface of the step; the thickness h' of the horizontal extension of the covering ring satisfies the following condition: h < h' < 1.3h.

[0021] On the other hand, this utility model also provides a plasma processing device, including: a reaction chamber, a lower electrode assembly as described above, disposed at the bottom of the reaction chamber; a gas spray head, located at the top of the reaction chamber and disposed opposite to the lower electrode assembly, for conveying reaction gas into the reaction chamber; and a radio frequency source, electrically connected to the base and / or the gas spray head, generating a radio frequency electric field between the base and the gas spray head to ionize the reaction gas and form plasma.

[0022] This utility model has at least one of the following technical effects:

[0023] This invention reduces the electric field strength near the top outer edge of the focusing ring by appropriately increasing the radius of the rounded corner. This significantly reduces the probability of arc discharge at the top outer edge of the focusing ring, and also reduces the ion bombardment intensity at that location. This helps to reduce the chance of the top outer edge of the focusing ring accidentally breaking due to excessively high local temperature, and prevents the problem of the top outer edge of the focusing ring breaking due to strong local ion bombardment.

[0024] This invention can further enhance the thickness of the cover ring by increasing the radius of the rounded corner at the top outer edge of the focusing ring. Increasing the thickness of the cover ring can extend its service life. Even when a certain thickness of the cover ring is etched away, it can still provide some protection to the top outer edge of the focusing ring, thereby further extending its service life, reducing the probability of arc discharge at the top outer edge of the focusing ring, and preventing the top outer edge of the focusing ring from shattering due to strong localized ion bombardment. Attached Figure Description

[0025] Figure 1 (a) is a cross-sectional schematic diagram of the focusing ring and the covering ring in the new part state in the prior art; Figure 1 (b) is a schematic diagram of the cross-section of the focusing ring and the covering ring after a certain number of hours of use in the prior art;

[0026] Figure 2 This is a schematic diagram of the structure of a plasma processing device provided in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the lower electrode assembly provided in Embodiment 1 of the present invention;

[0028] Figure 4 A cross-sectional schematic diagram of the lower electrode assembly provided in Embodiment 1 after a certain period of use;

[0029] Figure 5 This is a schematic diagram of the lower electrode assembly provided in Embodiment 2 of this utility model;

[0030] Figure 6 This is a cross-sectional schematic diagram of the lower electrode assembly after a certain number of hours of use.

[0031] Figure 7 This is a schematic diagram of the lower electrode assembly provided in Embodiment 3 of this utility model;

[0032] Figure 8 This is a schematic diagram of the lower electrode assembly provided in Embodiment 4 of this utility model. Detailed Implementation

[0033] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed explanation of the lower electrode assembly and plasma processing device proposed in this utility model. The advantages and features of this utility model will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, intended only to facilitate and clearly illustrate the embodiments of this utility model. Please refer to the drawings to make the objectives, features, and advantages of this utility model more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this utility model, should still fall within the scope of the technical content disclosed in this utility model.

[0034] like Figure 2 As shown, this embodiment provides a plasma processing apparatus, such as a capacitively coupled plasma processing device (CCP) or an inductively coupled plasma processing device (ICP). The plasma processing apparatus includes a vacuum-ejectable reaction chamber 10 surrounded by reaction chamber walls. A lower electrode assembly 16 is provided on the bottom wall of the reaction chamber 10. The lower electrode assembly 16 includes a base 11, disposed on the bottom wall of the reaction chamber 10, for supporting and placing a wafer W. The base 11 may be made of aluminum.

[0035] The gas spray head 12 is located at the top of the reaction chamber 10, opposite to the lower electrode assembly 16, and connected to the reaction gas source to introduce the reaction gas for the etching process and maintain a certain flow rate.

[0036] Radio frequency source ( Figure 2(Not shown in the diagram), is electrically connected to and applies radio frequency power RF to the base 11 and / or the gas spray head 12, generates a radio frequency electric field between the base 11 and the gas spray head 12, ionizes the reactive gas to form plasma P, and performs surface etching and other process treatments on the wafer W.

[0037] Combination Figure 3 As shown, in this embodiment, the lower electrode assembly 16 further includes a focusing ring 13, which is disposed on the base 11 and surrounds the wafer W. The focusing ring 13 is generally made of silicon or silicon carbide. By coupling a portion of the radio frequency energy to the focusing ring 13, a uniformly distributed plasma sheath layer P1 can be formed at the edge of the wafer W, thereby improving the etching consistency at the edge of the wafer W.

[0038] Please continue to refer to this. Figure 3 As shown, the top outer edge of the focusing ring 13 is provided with a rounded corner 130 transition, and the radius of the rounded corner 130 is greater than or equal to 0.4mm.

[0039] This embodiment reduces the electric field strength near the top outer edge of the focusing ring by appropriately increasing the radius of the rounded corner. This significantly reduces the probability of arc discharge at the top outer edge of the focusing ring, and also reduces the ion bombardment intensity at that location. This helps to reduce the probability of the top outer edge of the focusing ring accidentally breaking due to excessively high local temperature, and prevents the problem of the top outer edge of the focusing ring breaking due to strong local ion bombardment.

[0040] In this embodiment, the radius of the fillet 130 ranges from 0.4 mm to 1 mm. Within this radius range, the fillet 130 is large enough to reduce the probability of arc discharge at the top outer edge of the focusing ring and accidental breakage of the top outer edge of the focusing ring due to excessively high local temperature, while also preventing the fillet 130 from being too round, which could reduce the plasma blocking effect.

[0041] Please continue to refer to this. Figure 3 As shown, this embodiment also includes a cover ring 14, which surrounds the focusing ring 13 and is mounted on the edge of the base 11. The cover ring 14 is typically made of quartz. Figure 4 As shown, Figure 3 The diagram shows a cross-sectional view of the focusing ring 13 and the cover ring 14 in the lower electrode assembly after a certain number of hours of use. The top edge 140 of the inner ring of the cover ring 14 is thinned by etching, so that the top outer edge 130 of the focusing ring 13 is more exposed to ion bombardment.

[0042] For the tip discharge model, the electric field intensity E at the tip is:

[0043]

[0044] Where σ is the surface charge density and ε0 is the vacuum permittivity. The surface charge density of a conductor is related to its surface radius of curvature R as follows: Therefore, the electric field intensity E near the surface of the conductor is inversely proportional to the surface radius of curvature R, that is:

[0045] Based on the above relationship, this embodiment increases the radius of the fillet 130 of the top outer edge of the focusing ring 13 (for example, to 1.0 mm), thereby reducing the electric field strength near the position, thus reducing the probability of arc discharge at this position. At the same time, the ion bombardment intensity at this position is also reduced accordingly, which helps to reduce the probability of the top outer edge of the focusing ring 13 accidentally breaking due to excessively high local temperature.

[0046] like Figure 5 As shown, in this embodiment or some other embodiments, the upper surface B1 of the cover ring 14 is not lower than the upper surface B2 of the focusing ring 13. Therefore, this embodiment can also appropriately increase the thickness of the cover ring by increasing the radius of the rounded corner at the top outer edge of the focusing ring. Increasing the thickness of the cover ring can extend its service life, such as... Figure 6 As shown, when a certain thickness of the cover ring 14 is etched away, the cover ring 14 can still provide some protection for the top outer edge of the focusing ring 13, thereby further extending the service life of the focusing ring 13, further reducing the probability of arc discharge at the top outer edge of the focusing ring 13, and preventing the top outer edge of the focusing ring 13 from breaking due to strong local ion bombardment.

[0047] Please continue to refer to this. Figure 5 As shown, in this embodiment or some other embodiments, the height difference h” between the upper surface B1 of the covering ring 14 and the upper surface B2 of the focusing ring 13 is 0.5mm to 1.5mm. If the upper surface B1 of the covering ring 14 is too high, it will increase the flow resistance of the reactive gas and disrupt the uniformity of the reactive gas flow.

[0048] Please continue to refer to this. Figure 2 and Figure 5 As shown, in this embodiment, a step 131 is provided on the outer periphery of the focusing ring 13, and the upper surface B2 of the focusing ring 13 is higher than the top surface B3 of the step 131; the radial cross-section of the covering ring 14 is L-shaped, including a horizontal extension section 141 and a vertical extension section 142, the inner side of the horizontal extension section 141 covers the top surface B3 of the step 131, and the vertical extension section 142 covers part of the sidewall of the base 11.

[0049] In this embodiment, there is a distance h between the upper surface B2 of the focusing ring 13 and the top surface B3 of the step 131; the thickness h' of the horizontal extension 141 of the covering ring 14 satisfies the following condition: h < h' < 1.3h. Therefore, the service life of the focusing ring can be extended without affecting the uniformity of the reaction gas flow.

[0050] In some other embodiments, such as Figure 7 As shown, a chamfer 133 is provided on the fillet 130 on the top outer edge of the focusing ring 13. In this embodiment, both ends of the chamfer 133 are transitioned by sub-fillets 132.

[0051] That is, in this embodiment, a chamfer 133 can be made on the basis of the rounded corner 130, or the corner of the outer edge of the top of the focusing ring 13 can be directly changed to a bevel to form a chamfer 133, with the two ends of the bevel transitioned with rounded corners (i.e., sub-rounded corners 132). This can also reduce the probability of arc discharge and the probability of the outer edge of the focusing ring 13 breaking.

[0052] In this embodiment, the radius of the sub-rounded corner 132 ranges from 1mm to 2mm.

[0053] In some other embodiments, such as Figure 8 As shown, based on Figure 7 In the embodiment shown, by appropriately increasing the thickness of the cover ring 14, the service life of the focusing ring 13 can be further extended.

[0054] For details, please continue to refer to [the website / information]. Figure 8 As shown, the upper surface B1 of the cover ring 14 is not lower than the upper surface B2 of the focusing ring 13. Therefore, in this embodiment, the thickness of the cover ring can be appropriately increased based on increasing the radius of the rounded corner of the top outer edge of the focusing ring. Increasing the thickness of the cover ring can extend its service life. Thus, even when a certain thickness of the cover ring 14 is etched away, it can still provide some protection to the top outer edge of the focusing ring 13, further extending its service life and reducing the probability of arc discharge at the top outer edge of the focusing ring 13, preventing the top outer edge of the focusing ring 13 from shattering due to strong localized ion bombardment.

[0055] Please continue to refer to this. Figure 8 As shown, in this embodiment or some other embodiments, the height difference h” between the upper surface B1 of the covering ring 14 and the upper surface B2 of the focusing ring 13 is 0.5mm to 1.5mm. If the upper surface B1 of the covering ring 14 is too high, it will increase the flow resistance of the reactive gas and disrupt the uniformity of the reactive gas flow.

[0056] Please continue to refer to this. Figure 2 and Figure 8 As shown, in this embodiment, a step 131 is provided on the outer periphery of the focusing ring 13, and the upper surface B2 of the focusing ring 13 is higher than the top surface B3 of the step 131; the radial cross-section of the covering ring 14 is L-shaped, including a horizontal extension section 141 and a vertical extension section 142, the inner side of the horizontal extension section 141 covers the top surface B3 of the step 131, and the vertical extension section 142 covers part of the sidewall of the base 11.

[0057] In this embodiment, there is a distance h between the upper surface B2 of the focusing ring 13 and the top surface B3 of the step 131; the thickness h' of the horizontal extension 141 of the covering ring 14 satisfies the following condition: h < h' < 1.3h. Therefore, the service life of the focusing ring can be extended without affecting the uniformity of the reaction gas flow.

[0058] Please continue to refer to this. Figure 2 As shown, the lower electrode assembly 16 may further include a plasma confinement ring 17 surrounding the covering ring 14. The plasma confinement ring 17 has an exhaust channel. By reasonably setting the depth-to-width ratio of the exhaust channel, the plasma is confined to the reaction area between the upper and lower electrodes while the reactive gas is discharged, preventing plasma leakage into the non-reactive area and causing damage to the components in the non-reactive area. A grounding ring assembly 15 is also provided below the covering ring 14, that is, the covering ring 14 can be provided on the grounding ring assembly 15, and its vertical extension 142 can partially cover the sidewall of the grounding ring assembly 15. Generally, the grounding ring assembly 15 includes a grounding ring (not shown in the figure) and a shielding ring (not shown in the figure) arranged sequentially around the base 11. The shielding ring is used to shield the radio frequency signal applied to the base 11 within the base 11.

[0059] An electrostatic chuck (not shown in the figure) is also provided above the base 11. The electrostatic chuck is used to generate electrostatic attraction to support and fix the wafer W during the process. The focusing ring 13 can be arranged around the electrostatic chuck and the wafer W.

[0060] In summary, by appropriately increasing the radius of the rounded corners of the outer edge of the focusing ring, this invention can reduce the electric field strength near that location, thereby significantly reducing the probability of arc discharge at the top outer edge of the focusing ring. At the same time, the ion bombardment intensity at that location is also reduced accordingly, which helps to reduce the probability of the outer edge of the focusing ring accidentally breaking due to excessively high local temperature and prevents the problem of the top outer edge of the focusing ring breaking due to strong local ion bombardment.

[0061] This invention can further enhance the thickness of the cover ring by increasing the radius of the rounded corner at the top outer edge of the focusing ring. Increasing the thickness of the cover ring can extend its service life. Even when a certain thickness of the cover ring is etched away, it can still provide some protection to the top outer edge of the focusing ring, thereby further extending its service life, reducing the probability of arc discharge at the top outer edge of the focusing ring, and preventing the top outer edge of the focusing ring from shattering due to strong localized ion bombardment.

[0062] In the description of this utility model, it should be understood that the terms "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0063] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0064] Although the present invention has been described in detail through the above preferred embodiments, 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 content. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A lower electrode assembly, characterized in that, include: A base for supporting a wafer; A focusing ring is disposed on the base and surrounds the wafer; The top outer edge of the focusing ring has a rounded transition, and the radius of the rounded corner is greater than or equal to 0.4 mm.

2. The lower electrode assembly as described in claim 1, characterized in that, The radius of the fillet is in the range of 0.4mm to 1mm.

3. A lower electrode assembly, characterized in that, include: A base for supporting a wafer; A focusing ring is disposed on the base and surrounds the wafer; The focusing ring has a sloping surface at the top outer edge.

4. The lower electrode assembly as described in claim 3, characterized in that, The two ends of the inclined plane are transitioned with sub-rounded corners.

5. The lower electrode assembly as described in claim 4, characterized in that, The radius of the sub-rounded corner is in the range of 1mm to 2mm.

6. The lower electrode assembly as described in any one of claims 1 to 5, characterized in that, Also includes: A cover ring is disposed around the outside of the focusing ring.

7. The lower electrode assembly as described in claim 6, characterized in that, The upper surface of the cover ring is not lower than the upper surface of the focusing ring.

8. The lower electrode assembly as described in claim 7, characterized in that, The height difference between the upper surface of the cover ring and the upper surface of the focusing ring is 0.5mm to 1.5mm.

9. The lower electrode assembly as described in claim 6, characterized in that, A step is provided on the outer periphery of the focusing ring, and the upper surface of the focusing ring is higher than the top surface of the step; The radial cross-section of the covering ring is L-shaped, including a horizontal extension and a vertical extension. The inner side of the horizontal extension covers the top surface of the step, and the vertical extension covers part of the sidewall of the base.

10. The lower electrode assembly as claimed in claim 9, characterized in that, There is a distance h between the upper surface of the focusing ring and the top surface of the step; the thickness h' of the horizontal extension of the covering ring satisfies the following condition: h < h' < 1.3h.

11. A plasma processing device, characterized in that, include: The reaction chamber, as described in any one of claims 1 to 10, is disposed at the bottom of the reaction chamber; A gas spray head, located at the top of the reaction chamber and opposite to the lower electrode assembly, is used to deliver reaction gas into the reaction chamber; A radio frequency source is electrically connected to the base and / or the gas spray head, generating a radio frequency electric field between the base and the gas spray head to ionize the reactive gas and form plasma.

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