Ion filters and process chambers

Abstract

This invention discloses an ion filter and a process chamber. The ion filter includes: a filter body having a plurality of filter holes; and at least one connecting portion connected to the outer periphery of the filter body and extending circumferentially around the filter body. The area of ​​the cross-section of the filter body perpendicular to its central axis gradually decreases away from the connecting portion. The ion filter of this invention can adjust the distribution density of free radicals and ions, thereby improving the etching quality of the wafer.

Description

Technical Field

[0001] This invention relates to the field of processing equipment technology, specifically to an ion filter and a process chamber. Background Technology

[0002] With the rapid development of semiconductor device manufacturing processes, the requirements for the performance and integration of semiconductor devices are becoming increasingly stringent, leading to the widespread application of plasma technology. In systems that utilize plasma for etching or deposition, the distribution of plasma within the process chamber has a significant impact on the uniformity of the etching results.

[0003] Semiconductor processing equipment outputs radio frequency (RF) power via an RF power supply, which is then connected to a coil through a matching converter. The RF power, coupled by the coil, generates plasma within the process chamber through a dielectric window. However, most semiconductor processing equipment includes a vacuum system, which results in excessively high gas flow rates at the wafer edges. This leads to shorter ion residence times at the wafer edges, higher ion density at the wafer center, and lower ion density at the edges. Insufficient etching at the wafer edges causes a footing effect, negatively impacting the etching quality. Summary of the Invention

[0004] This invention discloses an ion filter and a process chamber to improve the etching quality of wafers.

[0005] To achieve the above objectives, according to one aspect of the present invention, an ion filter is provided, comprising:

[0006] A filter body having a plurality of filter holes;

[0007] At least one connecting portion is connected to the outer periphery of the filter body portion and extends circumferentially around the filter body portion, wherein the area of ​​the filter body portion in a cross section perpendicular to the central axis of the filter body portion gradually decreases in the direction away from the connecting portion.

[0008] In some alternative embodiments, the filter body is a conical structure.

[0009] In some alternative embodiments, the acute angle β formed between the outer peripheral surface of the filter body and the plane where the connecting part is located is greater than or equal to 5 degrees and less than or equal to 20 degrees.

[0010] According to another aspect of the present invention, a process chamber is provided, comprising:

[0011] The cavity has a filter port;

[0012] The aforementioned ion filter element is located at the filter port.

[0013] In some alternative embodiments, the cavity includes:

[0014] The second reaction chamber is equipped with a wafer carrier, and the filter port is provided on the top wall of the second reaction chamber;

[0015] The first reaction chamber is located above the second reaction chamber. One end of the first reaction chamber is connected to the second reaction chamber through a filter port, and the other end of the first reaction chamber is used to connect to the air intake assembly.

[0016] In some alternative embodiments, the connecting portion of the ion filter is closer to the first reaction chamber than the filter body portion of the ion filter, and the filter holes of the filter body portion are in communication with the first reaction chamber and the second reaction chamber.

[0017] In some alternative embodiments, the filter body is coaxial with the wafer carrier.

[0018] In some alternative embodiments, the wafer carrier has a carrier surface for carrying the wafer, and the ratio of the projected area of ​​the filter body portion on the wafer carrier to the area of ​​the carrier surface is greater than or equal to 0.3 and less than or equal to 0.6.

[0019] In some alternative embodiments, the maximum distance between the wafer carrier and the connection portion is a first distance, and the minimum distance between the wafer carrier and the filter body portion is a second distance, wherein the ratio of the second distance to the first distance is greater than or equal to 0.1 and less than or equal to 0.15.

[0020] In some alternative embodiments, the cavity is provided with a medium cylinder and a medium window, the medium cylinder forming the first reaction cavity, and the medium window serving as the top wall of the second reaction cavity.

[0021] In some alternative embodiments, the process chamber further includes an upper electrode assembly, which includes a first coil group and a second coil group coaxially sleeved on the outside of the dielectric cylinder, wherein the maximum distance from the first coil group to the dielectric cylinder is less than the minimum distance from the second coil group to the dielectric cylinder.

[0022] In some alternative embodiments, the minimum distance from the first coil group to the dielectric window is greater than the minimum distance from the second coil group to the dielectric window.

[0023] In some alternative embodiments, the ratio of the minimum distance from the end of the dielectric tube connected to the dielectric window to the first coil group to the length of the dielectric tube is greater than or equal to 0.33 and less than or equal to 0.67.

[0024] In some alternative embodiments, the ratio of the outer diameter of the dielectric cylinder to the inner diameter of the first coil group is greater than or equal to 0.8 and less than 1.

[0025] In some alternative embodiments, the ratio of the inner diameter of the first coil group to the inner diameter of the second coil group is greater than or equal to 0.2 and less than or equal to 0.5.

[0026] The ion filter disclosed in this invention includes a filter body and at least one connecting portion. The filter body has a plurality of filter holes. The connecting portion is connected to the outer periphery of the filter body and extends circumferentially around the filter body. The area of ​​the cross-section of the filter body perpendicular to the central axis of the filter body gradually decreases in the direction away from the connecting portion.

[0027] When plasma passes through the ion filter, most of the ions in the plasma are filtered out, while free radicals can pass through. In addition, since the cross-sectional area of ​​the filter body perpendicular to the central axis of the filter body gradually decreases away from the connection, the discharge space of ions at the end of the filter body away from the connection is compressed, resulting in a distribution state of low density at the center and high density at the edges.

[0028] Because the filter body has a dense and uniformly distributed number of filter holes, high-energy ions will collide and lose energy when passing through the filter holes. Therefore, the filter holes are selective for ions. When plasma containing ions and free radicals passes through the ion filter, the ions will lose energy. Therefore, the main components of the plasma after passing through the ion filter are free radicals and residual reactive gases. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the background art, the accompanying drawings used in the embodiments of the present invention or the background art will be described below.

[0030] Figure 1 A schematic diagram of the process chamber in an optional embodiment of the present invention is shown;

[0031] Figure 2 It shows Figure 1 A schematic diagram showing the positional relationship between the first and second coil groups and the dielectric cylinder;

[0032] Figure 3 It shows Figure 1 Side view of the medium ion filter element;

[0033] Figure 4 It shows Figure 1 A three-dimensional view of a medium ion filter element from one angle;

[0034] Figure 5 It shows Figure 1 Top view of the ion filter element;

[0035] Figure 6 This diagram illustrates the sheath distribution during wafer fabrication in a process chamber according to an optional embodiment of the present invention.

[0036] Figure 7 A simulation diagram of the ion density distribution from the center to the edge of a wafer in a process chamber according to an alternative embodiment of the present invention is shown.

[0037] 12. Connecting hole; 20. Upper electrode assembly; 21. First coil group; 211. First coil group; 212. First connecting post; 22. Second coil group; 221. Second coil section; 222. Second connecting post; 23. Upper RF power supply; 24. Upper matching unit; 241. Power divider network; 31. First reaction chamber; 32. Dielectric cylinder; 33. Dielectric window; 40. Second reaction chamber; 41. Filter port; 50. Ion filter element; 51. Filter body section; 511. Filter hole; 512. Large diameter end; 52. Connecting part; 521. Mounting hole; 60. Wafer carrier; 61. Carrier surface; 70. Inlet assembly; 80. Lower electrode assembly; 81. Lower RF power supply; 82. Lower matching unit; 83. Coaxial feed structure; 84. Support ring; 90. Sheath layer; 100. Wafer. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] As an optional implementation of the disclosure of this invention, an embodiment of this invention discloses an ion filter, such as... Figure 1 and Figure 3 As shown, the ion filter 50 includes a filter body portion 51 and at least one connecting portion 52. The filter body portion 51 has a plurality of filter holes 511. The connecting portion is connected to the outer periphery of the filter body portion 51, and the connecting portion 52 extends around the circumference of the filter body portion 51. The area of ​​the cross section of the filter body portion 51 perpendicular to the central axis of the filter body portion 51 gradually decreases in the direction away from the connecting portion 52.

[0040] When the plasma passes through the ion filter 50, most of the ions in the plasma are filtered out, while free radicals can pass through the ion filter 50. In addition, since the area of ​​the cross-section of the filter body 51 perpendicular to the central axis of the filter body 51 gradually decreases in the direction away from the connecting part 52, the discharge space of ions at the end of the filter body 51 away from the connecting part 52 is compressed, thereby causing the ions to exhibit a distribution state of low density at the center and high density at the edges.

[0041] Since the filter body 51 is provided with a dense and uniformly distributed plurality of filter holes 511, high-energy ions will collide and lose energy when passing through the filter holes 511. Therefore, the filter holes 511 are selective for ions. When plasma containing ions and free radicals passes through the ion filter 50, the ions will lose energy. Therefore, the main components of the plasma after passing through the ion filter 50 are free radicals and residual reactive gases.

[0042] In some alternative embodiments, such as Figures 3 to 5 As shown, the filter body 51 has a conical structure, and the large-diameter end 512 of the conical structure is connected to the connecting part 52.

[0043] In some alternative embodiments, there is one connecting portion 52, which is connected end to end around the filter body portion 51 in the circumferential direction.

[0044] In some alternative embodiments, there are multiple connecting portions 52, which are arranged circumferentially around the filter body portion 51. The specific structure of the connecting portions 52 is not specifically limited here and can be designed according to specific usage requirements.

[0045] As an optional implementation of the disclosed content of this invention, an embodiment of this invention discloses a process chamber, such as... Figure 1 As shown, Figure 1 This is a schematic diagram of a process chamber according to an embodiment of the present invention. The process chamber includes a cavity and the aforementioned ion filter 50. The cavity has a filter port 41; the ion filter 50 is located at the filter port 41. By placing the ion filter 50 at the filter port 41, a pair of ions in the gas passing through the filter port 41 are filtered out, allowing free radicals and residual reactive gases to pass through the filter port 41. This facilitates the adjustment of the distribution state of free radicals and ions within the cavity, which is beneficial for improving the etching quality of the wafer.

[0046] The cavity includes a second reaction chamber 40 and a first reaction chamber 31. A wafer carrier 60 is disposed within the second reaction chamber 40. A filter port 41 is disposed on the top wall of the second reaction chamber 40, located at the central reaction region of the second reaction chamber 40. Above the second reaction chamber 40, one end of the first reaction chamber 31 is connected to the second reaction chamber 40 through the filter port 41, and the other end of the first reaction chamber 31 is connected to the air intake assembly 70. The first plasma within the first reaction chamber 31 flows into the second reaction chamber 40 through the filter port 41.

[0047] like Figure 1 As shown, the ion filter 50 is located at the filter port 41. The ion filter 50 is configured to filter the gas flowing from the first reaction chamber 31 to the second reaction chamber 40, thereby filtering out ions from the plasma in the first reaction chamber 31 and allowing free radicals and residual reactive gas to flow into the second reaction chamber 40. Since the filter port 41 is located in the central reaction region of the second reaction chamber 40, free radicals enter the second reaction chamber and concentrate in the central reaction region of the second reaction chamber 40, resulting in a lower ion density in the central reaction region of the second reaction chamber 40 than the ion density in the edge reaction regions of the second reaction chamber 40. Since the thickness of the sheath is inversely proportional to the ion density, the sheath is thinner in areas with higher ion density. When the ion density in the central reaction region of the second reaction chamber 40 is lower than the ion density in the edge reaction region of the second reaction chamber 40, the sheath thickness at the edge of the wafer 100 is less than the sheath thickness at the center of the wafer 100. The direction of ion acceleration will be bent to the centripetal side, bombarding the footing on the centrifugal side of the edge, improving the effect of ion bombardment on the edge of the wafer 100, and reducing the footing phenomenon at the edge of the wafer 100.

[0048] It should be noted that the second reaction chamber 40 includes a wafer carrier device 60 for supporting the wafer 100. The wafer carrier device 60 has a carrier surface for supporting the wafer 100. The central reaction region of the second reaction chamber 40 refers to a cylindrical region formed with the perpendicular bisector of the carrier surface 61 as its central axis, and the minimum distance from the edge of the cylindrical region to the center of the carrier surface 61 is less than or equal to half of the minimum distance from the edge of the carrier surface 61 to the center of the carrier surface 61. In other words, the center point of the second reaction chamber 40 is not necessarily located in the central reaction region of the second reaction chamber 40, but the perpendicular bisector of the carrier surface 61 is coaxial with the central reaction region.

[0049] If the second reaction chamber 40 has multiple wafer 100 support devices, then the second reaction chamber 40 has multiple central reaction regions.

[0050] In some alternative embodiments, the reaction gas includes a fluorine-based gas. Of course, the reaction gas may also include other gaseous components, which are not specifically limited here.

[0051] In some alternative embodiments, a medium cylinder 32 and a medium window 33 are provided inside the cavity. The medium cylinder 32 surrounds the first reaction cavity 31, and the medium window serves as the top wall of the second reaction cavity 40. One end of the medium cylinder 32 is connected to the medium window 33, and the medium window 33 has a filter port 41. Both ends of the medium cylinder 32 are open structures, and the air intake assembly 70 is located at the end of the medium cylinder 32 away from the medium window 33. The reaction gas ejected from the air intake assembly 70 flows through the first reaction cavity 31 to the second reaction cavity 40.

[0052] In some alternative embodiments, the medium cylinder 32 and the medium window 33 can be an integral structure or a separate structure; no specific limitation is made here.

[0053] In some alternative embodiments, the medium cylinder 32 and the medium window 33 are made of ceramic. Of course, the materials of the medium cylinder 32 and the medium window 33 can be the same or different; there is no specific limitation here, and the design can be based on the reaction gas.

[0054] In some alternative embodiments, the process chamber further includes an upper electrode assembly 20, a portion of which is located within the chamber. The upper electrode assembly 20 excites the reactive gases in the first reaction chamber 31 and the second reaction chamber 40 to generate plasma. The reactive gases flow from the first reaction chamber 31 into the second reaction chamber 40. Under the excitation of the upper electrode assembly 20, the reactive gases dissociate in the first reaction chamber 31 to generate a first plasma. Since the reactive gases are not fully dissociated in the first reaction chamber 31, and some reactive gases remain undissociated, the first plasma comprises free radicals, ions, and residual reactive gases. The remaining reactive gases can enter the second reaction chamber 40 and dissociate to generate a second plasma.

[0055] Since only free radicals and residual reactive gases in the first plasma can enter the second reaction chamber 40, free radical etching is achieved. The residual gas entering the second reaction chamber 40 is ionized by the upper electrode assembly 20 to generate a second plasma. Since the ion density in the second plasma is greater than the free radical density, ion etching is achieved. By adjusting the power distribution of the upper electrode assembly 20, the ratio of free radicals to ions can be adjusted, enabling precise etching of free radicals and ions simultaneously.

[0056] In some alternative embodiments, the ion filter 50 and the media window 33 are an integral structure. In other alternative embodiments, the ion filter 50 and the media window 33 are separate structures, and the ion filter 50 and the media window 33 are connected, for example, the ion filter 50 and the media window 33 are detachably connected.

[0057] In some alternative embodiments, the ion filter element 50 is made of aluminum.

[0058] In some alternative embodiments, such as Figure 1 , Figures 3 to 5 As shown, the ion filter 50 includes a filter body 51, which has a plurality of filter holes 511. The filter holes 511 are connected to the first reaction chamber 31 and the second reaction chamber 40. By providing a plurality of filter holes 511 on the filter body 51, not only can ions be filtered out, but the gas flowing from the first reaction chamber 31 into the second reaction chamber 40 can also be uniformly distributed to avoid excessive concentration of gas in the second reaction chamber 40 and to ensure the etching morphology of the wafer 100.

[0059] In some alternative embodiments, such as Figures 3 to 5 As shown, the ion filter 50 further includes at least one connecting portion 52, which is connected to the surface of the media window 33 facing the second reaction chamber 40, and the connecting portion 52 is arranged circumferentially around the filter body portion 51. The connection portion 52 facilitates the connection between the ion filter 50 and the media window 33.

[0060] In some alternative embodiments, such as Figures 3 to 5 As shown, the connecting part 52 is detachably connected to the medium window 33. For example, the connecting part 52 has a mounting hole 521, through which a resin screw passes to connect to the medium window 33.

[0061] In some alternative embodiments, such as Figures 3 to 5 As shown, the filter body 51 has a conical structure. The large-diameter end 512 of the conical structure is connected to the connecting part 52, and the conical structure is located on the side of the connecting part 52 away from the media window 33. The large-diameter end 512 of the conical structure and the connecting part 52 are integrally formed. The conical structure extends from the connecting part 52 to the side away from the media window 33, and the sharp corner of the conical structure is farthest from the connecting part 52, so that the sharp corner of the conical structure is closest to the center of the wafer 100.

[0062] In some alternative embodiments, such as Figure 1As shown, the filter body 51 is coaxial with the wafer carrier 60. The filter body 51 has a conical structure, and the wafer 100 is coaxially placed on the wafer carrier 60 so that the conical structure is coaxial with the wafer 100, and the sharp corner of the conical structure is closest to the wafer 100. This results in a smaller discharge height below the filter hole 511 near the sharp corner of the conical structure, and a smaller discharge space V1 corresponding to the filter hole 511 near the sharp corner, while a larger discharge height below the filter hole 511 away from the sharp corner, and a larger discharge space V2 below the filter hole 511 away from the sharp corner. Since the contact area S between the plasma and the ion filter 50 is considered to be the same, the S / V1 of the filter hole 511 near the sharp corner is relatively large, and the plasma surface loss is greater, resulting in a lower ion density near the sharp corner. Conversely, the S / V2 of the filter hole far from the sharp corner is relatively small, and the plasma surface loss is less, resulting in a higher ion density far from the sharp corner. This leads to a phenomenon where the ion density is low at the center of the wafer 100 and gradually increases from the center of the wafer 100 to the edge of the wafer 100, reducing the footing phenomenon at the edge of the wafer 100 and improving the etching morphology of the edge of the wafer 100.

[0063] In some alternative embodiments, such as Figure 1 As shown, the wafer carrier 60 has a carrier surface 61 for carrying the wafer 100. The ratio of the projected area of ​​the cone structure's orthographic projection on the wafer carrier 60 to the area of ​​the carrier surface 61 is greater than or equal to 0.3 and less than or equal to 0.6. This arrangement can further increase the ion density difference between the edge reaction region and the central reaction region of the second reaction chamber 40, which is beneficial to improving the etching effect on the edge of the wafer 100 and avoiding the generation of footing. For example, the ratio of the projected area of ​​the cone structure's orthographic projection on the wafer carrier 60 to the area of ​​the carrier surface 61 is 0.4. The ratio of the projected area of ​​the cone structure's orthographic projection on the wafer carrier 60 to the area of ​​the carrier surface 61 is 0.5.

[0064] In some alternative embodiments, such as Figure 1 As shown, the maximum distance between the wafer carrier 60 and the connecting part 52 is the first distance H1, and the minimum distance between the wafer carrier 60 and the conical structure is the second distance H2. The ratio of the second distance H2 to the first distance H1 is greater than or equal to 0.1 and less than or equal to 0.15. This arrangement ensures that there is a certain ionization space between the ion filter 50 and the center of the wafer 100, ensuring that ions are generated at the center of the wafer 100, so that the ions can etch the center of the wafer 100, thereby ensuring the uniformity of the etching of the wafer 100.

[0065] In some alternative embodiments, such as Figure 3As shown, the acute angle β formed between the conical structure and the surface facing the second reaction chamber 40 is greater than or equal to 5 degrees and less than or equal to 20 degrees. This arrangement, while ensuring uniform etching of the wafer 100, is beneficial for further increasing the ion density in the edge reaction region and further decreasing the ion density in the central reaction region, thereby further reducing the risk of footing at the edge of the wafer 100.

[0066] In some alternative embodiments, the ratio of the ion density of the edge reaction region to the ion density of the central reaction region is greater than 1 to reduce the risk of footing at the edge of wafer 100.

[0067] In some alternative embodiments, the ion filter element 50 may be disposed inside the filter port 41 or on one side of the filter port 41, without any specific limitation.

[0068] In some alternative embodiments, such as Figure 2 As shown, the upper electrode assembly 20 includes a first coil group 21 and a second coil group 22 coaxially sleeved on the outside of the dielectric cylinder 32. The maximum distance from the first coil group 21 to the dielectric cylinder 32 is less than the minimum distance from the second coil group 22 to the dielectric cylinder 32. This arrangement allows the first coil group 21 of the upper electrode assembly 20 to ionize the reactive gas in the first reaction chamber 31 to generate a first plasma, while the second coil group 22 ionizes the reactive gas in the second reaction chamber 40 to generate a second plasma. This arrangement, whereby the second coil group 22 ionizes the reaction region at the edge of the second reaction chamber 40 to generate a second plasma, helps to increase the ion concentration in the reaction region at the edge of the second reaction chamber 40.

[0069] In some alternative embodiments, such as Figure 1 As shown, the minimum distance from the first coil group 21 to the dielectric window 33 is greater than the minimum distance from the second coil group 22 to the dielectric window 33. This arrangement allows the second coil group 22, located outside the first coil group 21, to be closer to the dielectric window 33. This facilitates the second coil group 22 in fully exciting the remaining reactive gas in the second reaction chamber 40 to ionize and generate the second plasma. At the same time, since the second coil group 22 is farther from the first reaction chamber 31, it helps to improve the ionization efficiency of the edge reaction region in the second reaction chamber 40 and increase the ion density in the edge reaction region.

[0070] In some optional embodiments, the ratio of the minimum distance from the end of the dielectric cylinder 32 connected to the dielectric window 33 to the first coil group 21 to the length of the dielectric cylinder 32 is greater than or equal to 0.33 and less than or equal to 0.67. Limiting this ratio within a reasonable range ensures that the electromagnetic field generated by the first coil group 21 covers the area of ​​the first reaction chamber 31, thereby ensuring the ionization efficiency of the reactant gas in the first reaction chamber 31.

[0071] In some alternative embodiments, the ratio of the outer diameter of the dielectric cylinder 32 to the inner diameter of the first coil group 21 is greater than or equal to 0.8 and less than 1. This arrangement ensures that the electromagnetic field generated by the first coil group 21 covers the range of the first reaction chamber 31, thus guaranteeing the ionization efficiency of the reaction gas in the first reaction chamber 31.

[0072] In some alternative embodiments, the ratio of the inner diameter of the first coil group 21 to the inner diameter of the second coil group 22 is greater than or equal to 0.2 and less than or equal to 0.5. This arrangement ensures that the second coil group 22 is at a certain distance from the central reaction region of the second reaction cavity 40, and is closer to the edge reaction region of the second reaction cavity 40. This helps to increase the ion density in the edge reaction region of the second reaction cavity 40, reduce the ion density in the central reaction region, and reduce the footing phenomenon at the edge of the wafer 100.

[0073] In some alternative embodiments, please refer to Figure 1 The upper electrode assembly 20 also includes an upper RF power supply 23 and an upper matching unit 24. The upper RF power supply 23 is connected to the upper matching unit 24 via a coaxial cable. The upper RF power supply 23 provides RF power to the first coil group 21 and the second coil group 22 through the upper matching unit 24, so that the first coil group 21 excites the reaction gas in the first reaction chamber 31 to generate the first plasma, and the second coil group 22 excites the reaction gas in the second reaction chamber 40 to generate the second plasma.

[0074] The upper matching unit 24 includes a power divider network 241, which can adjust the current output ratio of the first coil group and the second coil group through an internal capacitor.

[0075] like Figure 2 As shown, the first coil group 21 includes a first coil group 211 and a plurality of first connecting posts 212. One end of the first connecting post 212 is connected to the first coil group 211, and the other end of the first connecting post 212 is connected to the upper matching unit 24. The power provided by the upper matching unit 24 is fed into the first coil group 211 through the plurality of first connecting posts 212.

[0076] like Figure 2As shown, the second coil group 22 includes a second coil section 221 and a plurality of second connecting posts 222. One end of the second connecting post 222 is connected to the second coil section 221, and the other end of the second connecting post 222 is connected to the upper matching unit 24. The power provided by the upper matching unit 24 is fed into the second coil section 221 through the plurality of second connecting posts 222.

[0077] In some alternative embodiments, please refer to Figure 1 The process chamber also includes a lower electrode assembly 80, which includes a wafer carrier 60, a lower RF power supply 81, a lower matching unit 82, a coaxial feed structure 83, and a support ring 84. The lower RF power supply 81 is connected to the lower matching unit 82 via a coaxial cable, and the lower matching unit 82 is fed into the wafer carrier 60 via the coaxial feed structure 83, thereby enabling the wafer carrier 60 to...

[0078] In some alternative embodiments, the bottom wall of the process chamber has at least one connection hole 12, the support ring 84 is located in the second reaction chamber 40 and is connected to the bottom wall of the process chamber, the support ring 84 is coaxial with the connection hole 12, and the wafer carrier device 60 is disposed on the support ring 84 and covers the central hole of the support ring 84. The coaxial power supply structure 83 passes through the central hole and the support ring 84 and is connected to the wafer carrier device 60.

[0079] Theoretically, the ion movement trajectory is perpendicular to the sheath layer 90. In order to avoid footing on the edge side of the wafer 100, the ideal distribution trend of the sheath layer 90 should be that the edge sheath layer 90 is thinner and the center sheath layer 90 is thicker. This can avoid the footing phenomenon. The sheath layer is usually uniformly distributed above the wafer 100, and the shell layer distribution cannot be effectively adjusted.

[0080] However, the thickness of the sheath 90 is proportional to the Debye length, and the thickness s of the sheath and the Debye length λ D The calculation formula is as follows:

[0081]

[0082] In the above formula, s is the thickness of the sheath in mm; λD is the Debye length in mm; e is the charge in coulombs (C); and φ0 is the electric potential in volts (V). ne is the electron temperature, measured in electron volts (eV); ne is the ion density, measured in cm³. 3 ε0 is the vacuum permittivity, specifically 8.854187817 × 10⁻⁶. -12 F / m.

[0083] That is, the thickness of the sheath layer 90 is inversely proportional to the ion density; the higher the ion density, the thinner the sheath layer 90. In other words, since the ion density is inversely proportional to the thickness of the sheath layer 90, and in this invention, the ion density is low at the center of wafer 100 and high at the edges, the sheath layer 90 on wafer 100 in this invention is thicker at the center and thinner at the edges, forming an ideal sheath layer distribution trend. The distribution trend of the sheath layer 90 is described in [reference needed]. Figure 6 .

[0084] In addition, Figure 6 In the diagram, the direction of the arrow represents the trajectory of the ions. The angle between the trajectory of the ions and the X-axis is denoted as θ. The magnitude of this value can characterize the magnitude of the electric field component in the X-axis. The closer θ is to 0, the greater the force on the ions in the X-axis direction, and the more obvious the etching effect on the footing. In this application, the intensity of ion etching at the edge of wafer 100 is controlled by adjusting the ion density at the edge and center of wafer 100.

[0085] Simulation data of ion density distribution from the center to the edge of wafer 100 are as follows: Figure 7 As shown, from Figure 7 As can be seen, the ion density at the edge of wafer 100 is higher than that at the center. When the power of the upper electrode increases, the ion density at the edge of wafer 100 increases significantly, while the increase at the center is smaller. According to the sheath theory, a very thin sheath will form at the edge of wafer 100, while the sheath at the center of wafer 100 is thicker due to the lower plasma density. The direction of ion acceleration will be bent towards the centripetal side, bombarding the footing on the centrifugal side of the edge. The magnitude of the bombardment force can be controlled by the current ratio and the power of the upper electrode. By adjusting the current ratio and the power of the upper electrode, the ratio of the ion density at the edge to that at the center of wafer 100 can be changed, allowing for targeted treatment of different footing morphologies.

[0086] In summary, the process chamber of this invention can meet the requirements of free radical etching in BVR process and can also precisely control ion etching. At the same time, the dominant element of etching can be adjusted by the upper electrode assembly 20, which reduces the footing phenomenon and improves the etching morphology of the edge of wafer 100.

[0087] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The above embodiments are merely illustrative of several implementation methods described in detail, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this specification, and these all fall within the protection scope of this specification. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. An ion filter element, characterized in that, include: The filter body (51) has a plurality of filter holes (511); At least one connecting portion (52) is connected to the outer periphery of the filter body portion (51) and the connecting portion (52) extends circumferentially around the filter body portion (51). The area of ​​the cross section of the filter body portion (51) perpendicular to the central axis of the filter body portion (51) gradually decreases in the direction away from the connecting portion (52).

2. The ion filter element according to claim 1, characterized in that, The filter body (51) has a conical structure.

3. The ion filter element according to claim 2, characterized in that, The acute angle β formed between the outer peripheral surface of the filter body (51) and the plane where the connecting part (52) is located is greater than or equal to 5 degrees and less than or equal to 20 degrees.

4. A process chamber, characterized in that, include: The cavity has a filter port (41). ； The ion filter (50) according to any one of claims 1 to 3, wherein the ion filter (50) is located at the filter port (41).

5. The process chamber according to claim 4, characterized in that, The cavity includes: The second reaction chamber (40) is provided with a wafer carrier device (60), and the top wall of the second reaction chamber (40) is provided with the filter port (41); The first reaction chamber (31) is located above the second reaction chamber (40). One end of the first reaction chamber (31) is connected to the second reaction chamber (40) through the filter port (41), and the other end of the first reaction chamber (31) is used to connect to the air intake assembly (70).

6. The process chamber according to claim 5, characterized in that, The connecting portion (52) of the ion filter (50) is close to the first reaction chamber (31) relative to the filter body portion (51) of the ion filter (50), and the filter hole (511) of the filter body portion (51) is in communication with the first reaction chamber (31) and the second reaction chamber (40).

7. The process chamber according to claim 6, characterized in that, The filter body (51) is coaxial with the wafer carrier (60).

8. The process chamber according to claim 7, characterized in that, The wafer carrier device (60) has a carrier surface (61) for carrying wafers, and the ratio of the projected area of ​​the filter body part (51) on the wafer carrier device (60) to the area of ​​the carrier surface (61) is greater than or equal to 0.3 and less than or equal to 0.

6.

9. The process chamber according to claim 7, characterized in that, The maximum distance between the wafer carrier (60) and the connecting part (52) is the first distance, and the minimum distance between the wafer carrier (60) and the filter body part (51) is the second distance. The ratio of the second distance to the first distance is greater than or equal to 0.1 and less than or equal to 0.

15.

10. The process chamber according to any one of claims 5 to 9, characterized in that, The cavity is provided with a medium cylinder (32) and a medium window (33). The medium cylinder (32) surrounds the first reaction cavity (31), and the medium window serves as the top wall of the second reaction cavity (40).

11. The process chamber according to claim 10, characterized in that, The process chamber also includes an upper electrode assembly (20), which includes a first coil group (21) and a second coil group (22) coaxially sleeved on the outside of the dielectric cylinder (32). The maximum distance from the first coil group (21) to the dielectric cylinder (32) is less than the minimum distance from the second coil group (22) to the dielectric cylinder (32).

12. The process chamber according to claim 11, characterized in that, The minimum distance from the first coil group (21) to the dielectric window (33) is greater than the minimum distance from the second coil group (22) to the dielectric window (33).

13. The process chamber according to claim 11, characterized in that, The ratio of the minimum distance from the end of the dielectric tube (32) connected to the dielectric window (33) to the first coil group (21) to the length of the dielectric tube (32) is greater than or equal to 0.33 and less than or equal to 0.

67.

14. The process chamber according to claim 11, characterized in that, The ratio of the outer diameter of the medium cylinder (32) to the inner diameter of the first coil group (21) is greater than or equal to 0.8 and less than 1.

15. The process chamber according to claim 11, characterized in that, The ratio of the inner diameter of the first coil group (21) to the inner diameter of the second coil group (22) is greater than or equal to 0.2 and less than or equal to 0.5.

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