Ion filtering element and process chamber

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 a first surface on which the outlet ends of each filter hole are located, the center of which protrudes from the plane containing the edge of the filter body along the central axis of the filter body. 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. [Previous 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] In semiconductor processing equipment, the radio frequency power output from the radio frequency power supply is fed into the coil through a matching unit. The radio frequency power is coupled by the coil and generates plasma in the process chamber through the dielectric window. However, since the gas extraction device in most semiconductor processing equipment is set off from the axis of the process chamber, the gas flow rate at the edge of the wafer is faster than that at the center. This results in a shorter residence time for ions at the edge of the wafer, leading to a high ion density at the center of the wafer and a low ion density at the edge. Consequently, the edge etching of the wafer is insufficient, resulting in a footing phenomenon at the edge of the wafer, which affects the etching quality of the wafer. [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 objective, according to one aspect of the present invention, an ion filter is provided, comprising: a filter body portion having a plurality of filter holes; the filter body portion having a first surface on which the outlet end of each of the filter holes is located, the center of the first surface protruding out of the plane on which the edge of the filter body portion is located along the central axis of the filter body portion.

[0006] In some embodiments, the first surface is conical.

[0007] In some embodiments, the filter body is plate-shaped, and the filter body also has a second surface opposite to the first surface, and the inlet end of each filter hole is located on the second surface; the second surface is conical.

[0008] In some embodiments, the acute angle β formed between the first surface and the plane perpendicular to the central axis of the filter body is greater than or equal to 5 degrees and less than or equal to 20 degrees.

[0009] In some embodiments, at least one connecting portion is connected to the edge of the filter body portion and extends along the edge of the filter body portion.

[0010] In some embodiments, there is one connecting part, which is connected end to end along the edge of the filter body part, or there are multiple connecting parts, which are spaced apart along the edge of the filter body part.

[0011] According to another aspect of the present invention, a process chamber is provided, comprising: a cavity having a filter port; and the aforementioned ion filter, wherein the ion filter is located at the filter port.

[0012] In some embodiments, the cavity includes: a first reaction cavity and a second reaction cavity, wherein the second reaction cavity is provided with a wafer carrier device, and the top wall of the second reaction cavity is provided with the filter port; the first reaction cavity is located above the second reaction cavity, one end of the first reaction cavity is connected to the second reaction cavity through the filter holes of the filter body, and the other end of the first reaction cavity is used to connect with the air intake assembly; the first surface of the filter body is opposite to the bearing surface of the wafer carrier device.

[0013] In some embodiments, the filter body is coaxial with the wafer carrier.

[0014] In some embodiments, the ratio of the projected area of ​​the first surface 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.

[0015] In some embodiments, the distance between the bearing surface of the wafer carrier device and the lower surface of the top wall of the second reaction chamber is a first distance, and the minimum distance between the bearing surface of the wafer carrier device and the first surface is a 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.

[0016] In some embodiments, the cavity is provided with a medium cylinder and a medium window, the medium cylinder surrounds the first reaction cavity, and the medium window serves as the top wall of the second reaction cavity.

[0017] In some 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.

[0018] In some 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.

[0019] In some 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.

[0020] In some 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.

[0021] In some 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.

[0022] The ion filter disclosed in this invention includes a filter body portion having a plurality of filter holes; the filter body portion has a first surface where the outlet end of each filter hole is located, and the center of the first surface protrudes from the plane where the edge of the filter body portion is located along the central axis of the filter body portion.

[0023] When the plasma passes through the ion filter, most of the ions in the plasma are filtered out, while free radicals can pass through the ion filter. In addition, since the center of the first surface protrudes from the plane containing the edge of the filter body along the central axis of the filter body, the discharge space of ions on the side of the filter body adjacent to the center of the first surface is compressed, thereby causing the ions to exhibit a distribution state of low center density and high edge density.

[0024] Because the filter body is provided with 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.

Implementation Method

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] As one embodiment of the disclosed content of this invention, an ion filter element is disclosed. As shown in Figures 1 and 3, the ion filter element 50 includes a filter body portion 51, which has a plurality of filter holes 511. The filter body portion 51 has a first surface 513 where the outlet end of each filter hole 511 is located. The center of the first surface 513 protrudes from the plane where the edge of the filter body portion 51 is located along the central axis of the filter body portion 51 (i.e., the central axis O in Figure 3). The edge of the first surface 513 constitutes the edge 512 of the filter body portion 51.

[0028] When the plasma passes through the filter hole 511 of the ion filter 50, most of the ions in the plasma are filtered out, while free radicals can pass through the filter hole 511 of the ion filter 50. In addition, since the center of the first surface 513 protrudes from the plane containing the edge of the filter body 51 along the central axis of the filter body 51, the discharge space of ions on the side of the filter body 51 adjacent to the center of the first surface 513 is compressed, thereby causing the ions to exhibit a distribution state with low center density and high edge density.

[0029] Since the filter body 51 is provided with a plurality of densely and uniformly distributed filter holes 511, when high-energy ions pass through the filter holes 511, they will collide and lose energy. 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.

[0030] In some embodiments, as shown in Figures 3 to 5, the first surface 513 is conical. That is, the orthographic projection size of the first surface 513 on a plane perpendicular to the central axis of the filter body 51 gradually decreases at different positions of its edge toward the center.

[0031] Further, in some embodiments, the filter body 51 is plate-shaped, and the filter body 51 also has a second surface 514 facing away from the first surface 513, and the inlet end of each filter hole 511 is located on the second surface 514; the second surface 514 is conical.

[0032] In some embodiments, the ion filter 50 further includes at least one connecting portion 52, which is connected to the edge of the filter body portion 51 and extends along the edge of the filter body portion 51. In embodiments where both the first surface 513 and the second surface 514 are tapered, the edges of the first surface 513 and the second surface 514 form the edge 512 of the filter body portion 51 and are connected to the connecting portion 52.

[0033] Further, in some embodiments, there is one connecting portion 52, which is connected end to end along the edge of the filter body portion 51. That is, the connecting portion 52 is in the form of a closed loop, which surrounds the circumference of the filter body portion 51 and is connected to the edge of the filter body portion 51.

[0034] In some other embodiments, there are multiple connecting portions 52, which are spaced apart along the edge of the filter body portion 51. That is, multiple connecting portions 52 are spaced apart circumferentially along the filter body portion 51, and each connecting portion 52 is connected to the edge of 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.

[0035] As one embodiment of the present invention, an embodiment of the present invention discloses a process chamber, as shown in FIG1. ​​FIG1 is a schematic diagram of the structure of a process chamber disclosed in the 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. The ion filter 50 is placed at the filter port 41 to filter ions in the gas passing through the filter port 41, so that free radicals and residual reactive gases pass through the filter port 41, which facilitates the adjustment of the distribution state of free radicals and ions in the cavity and is beneficial to improving the etching quality of the wafer.

[0036] The cavity includes a first reaction chamber 31 and a second reaction chamber 40. A wafer carrier device 60 is disposed inside the second reaction chamber 40. A filter port 41 is disposed on the top wall of the second reaction chamber 40, and the filter port 41 is 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 used to connect to the air intake assembly 70. The first surface 513 of the filter body 50 is opposite to the bearing surface 61 of the wafer carrier device 60. The first plasma in the first reaction chamber 31 flows into the second reaction chamber 40 through the filter holes 511 of the ion filter element 50 at the filter port 41.

[0037] As shown in Figure 1, 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 40 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.

[0038] It should be noted that the second reaction chamber 40 has a wafer carrier device 60 for carrying the wafer 100. The wafer carrier device 60 has a carrier surface for carrying the wafer 100. The central reaction region of the second reaction chamber 40 refers to a columnar region formed with the perpendicular bisector of the carrier surface 61 as the central axis. The minimum distance from the orthographic projection of the boundary of the columnar region onto the carrier surface 61 to the center of the carrier surface 61 is less than or equal to half the minimum distance from the edge of the carrier surface 61 to the center of the carrier surface 61. That is to say, the central axis of the second reaction chamber 40 is not necessarily coaxial with 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.

[0039] If the second reaction chamber 40 has multiple wafer carrier devices 60, then the second reaction chamber 40 has multiple central reaction regions.

[0040] In some embodiments, the reaction gas includes fluorine-based gas. Of course, the reaction gas may also include other gas components, which are not specifically limited here.

[0041] In some 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 33 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.

[0042] In some embodiments, the medium cylinder 32 and the medium window 33 can be an integral structure or a separate structure, and no specific limitation is made here.

[0043] In some 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; no specific limitation is made here, and the design can be based on the reaction gas.

[0044] In some 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 into the second reaction chamber 40 through the first reaction chamber 31. 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 components of the first plasma include 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.

[0045] 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 density of ions in the second plasma is greater than the density of free radicals, 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, and precise etching of free radicals and ions simultaneously can be achieved.

[0046] In some embodiments, the ion filter 50 and the media window 33 are an integral structure. In other 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.

[0047] In some embodiments, the ion filter element 50 is made of aluminum.

[0048] In some embodiments, as shown in Figures 1, 3 to 5, 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 entering the second reaction chamber 40 and to ensure the etching morphology of the wafer 100.

[0049] In some embodiments, as shown in Figures 3 to 5, 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 is also connected to the edge of the filter body 51. The connecting portion 52 facilitates the connection between the ion filter 50 and the media window 33. In embodiments where both the first surface 513 and the second surface 514 are conical, the edges of the first surface 513 and the second surface 514 form the edge 512 of the filter body 51 and are connected to the connecting portion 52.

[0050] In some embodiments, as shown in Figures 3 to 5, 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 an insulating fastener, such as a resin screw, passes and is connected to the medium window 33.

[0051] In some embodiments, as shown in Figures 3 to 5, the filter body 51 is plate-shaped, and both the first surface 513 and the second surface 514 are conical. The edges of the first surface 513 and the second surface 514 form the edges 512 of the filter body 51. The edges 512 of the filter body 51 are connected to the connecting portion 52, and the filter body 51 is located on the side of the connecting portion 52 away from the media window 33. The edges 512 of the filter body 51 are integrally formed with the connecting portion 52. The filter body 51 extends from the connecting portion 52 to the side away from the media window 33, and the sharp corner of the filter body 51 (i.e., the center of the first surface 513) is furthest from the connecting portion 52, so that the sharp corner of the filter body 51 is closest to the center of the wafer 100.

[0052] In some embodiments, as shown in FIG1, the filter body 51 is coaxial with the wafer carrier 60. The wafer 100 is coaxially placed on the wafer carrier 60 such that the filter body 51 is coaxial with the wafer 100, and the sharp corner of the filter body 51 (i.e., the center of the first surface 513) is closest to the wafer 100, so that the discharge height below the filter hole 511 near the sharp corner in the filter body 51 is smaller, the discharge space V1 corresponding to the filter hole 511 near the sharp corner is smaller, while the discharge height below the filter hole 511 away from the sharp corner is larger, and the discharge space V2 below the filter hole 511 away from the sharp corner is larger. 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 511 away from the sharp corner is relatively small, and the plasma surface loss is less, resulting in a higher ion density away 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.

[0053] In some embodiments, as shown in FIG1, the wafer carrier device 60 has a carrier surface 61 for carrying the wafer 100, and the ratio of the projected area of ​​the orthographic projection of the first surface 513 of the filter body portion 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. 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 orthographic projection of the first surface 513 on the wafer carrier device 60 to the area of ​​the carrier surface 61 is 0.4. The ratio of the projected area of ​​the orthographic projection of the first surface 513 on the wafer carrier device 60 to the area of ​​the carrier surface 61 is 0.5.

[0054] In some embodiments, as shown in FIG1, the maximum distance between the wafer carrier 60 and the lower surface of the top wall (i.e., dielectric window 33) of the second reaction chamber 40 is a first distance H1, and the minimum distance between the wafer carrier 60 and the first surface 513 is a 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.

[0055] In some embodiments, as shown in FIG3, the acute angle β formed between the first surface 513 and the plane perpendicular to the central axis of the filter body portion 51 is greater than or equal to 5 degrees and less than or equal to 20 degrees. This arrangement, while ensuring the uniformity of etching the wafer 100, is beneficial to further increase the ion density in the edge reaction region and further reduce the ion density in the central reaction region, thereby further reducing the risk of footing at the edge of the wafer 100.

[0056] In some 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, so as to reduce the risk of footing at the edge of the wafer 100.

[0057] In some 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.

[0058] In some embodiments, as shown in FIG2, 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 reaction gas in the first reaction chamber 31 to generate a first plasma, while the second coil group 22 ionizes the reaction gas in the second reaction chamber 40 to generate a second plasma. This allows the second coil group 22 to ionize the reaction region at the edge of the second reaction chamber 40 to generate a second plasma, which is beneficial to increasing the ion concentration in the reaction region at the edge of the second reaction chamber 40.

[0059] In some embodiments, as shown in FIG1, 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 makes the second coil group 22, located outside the first coil group 21, closer to the dielectric window 33, which is beneficial for the second coil group 22 to fully excite 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 away from the first reaction chamber 31, it is beneficial 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.

[0060] In some 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.

[0061] In some 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, thereby ensuring the ionization efficiency of the reaction gas in the first reaction chamber 31.

[0062] In some 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.

[0063] In some embodiments, please refer to FIG1. ​​The upper electrode assembly 20 further includes an upper radio frequency power supply 23 and an upper matching unit 24. The upper radio frequency power supply 23 is connected to the upper matching unit 24 via a coaxial cable. The upper radio frequency power supply 23 provides radio frequency power to the first coil group 21 and the second coil group 22 via the upper matching unit 24, so that the first coil group 21 excites the reaction gas in the first reaction chamber 31 to generate a first plasma, and the second coil group 22 excites the reaction gas in the second reaction chamber 40 to generate a second plasma.

[0064] 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 by means of an internal capacitor.

[0065] As shown in Figure 2, the first coil group 21 includes a first coil section 211 and a plurality of first connecting posts 212. One end of the first connecting post 212 is connected to the first coil section 211, and the other end of the first connecting post 212 is connected to the upper matching device 24. The power provided by the upper matching device 24 is fed into the first coil section 211 through the plurality of first connecting posts 212.

[0066] As shown in Figure 2, 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 device 24. The power provided by the upper matching device 24 is fed into the second coil section 221 through the plurality of second connecting posts 222.

[0067] In some embodiments, referring to FIG1, the process chamber further includes a lower electrode assembly 80, which includes a wafer carrier 60, a lower RF power supply 81, a lower matching device 82, a coaxial feed structure 83, and a support ring 84. The lower RF power supply 81 is connected to the lower matching device 82 via a coaxial cable, and the lower matching device 82 is fed into the wafer carrier 60 via the coaxial feed structure 83, thereby enabling the wafer carrier 60 to...

[0068] In some 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 center hole of the support ring 84. The coaxial power supply structure 83 passes through the center hole and the support ring 84 and is connected to the wafer carrier device 60.

[0069] Theoretically, the trajectory of ion movement 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.

[0070] However, the thickness of the sheath 90 is proportional to the Debye length. The formulas for calculating the thickness s of the sheath and the Debye length λD are as follows: In the above formulas, s is the thickness of the sheath in mm; λD is the Debye length in mm; e is the charge in coulombs C; is the electric potential in volts V; is the electron temperature in electron volts eV; ne is the ion density in cm3; and is the vacuum dielectric constant, specifically 8.854187817×10-12 F / m.

[0071] 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 the ion density is low at the center of the wafer 100 and high at the edge of the wafer 100 in this invention, the sheath layer 90 on the wafer 100 in this invention is thick at the center and thin at the edge, forming an ideal sheath layer distribution trend. The distribution trend of the sheath layer 90 is shown in Figure 6.

[0072] Furthermore, in Figure 6, the direction of the arrow is the trajectory of the ion. The angle between the trajectory of the ion and the X-axis is denoted as θ. The magnitude of this value can characterize the magnitude of the electric field in the X-axis component. The closer θ is to 0, the greater the force on the ion in the X-axis direction, and the more obvious the etching effect on the footing. The present invention controls the intensity of ion etching at the edge of the wafer 100 by adjusting the ion density at the edge and center of the wafer 100.

[0073] The simulation data of the ion density distribution from the center to the edge of wafer 100 is shown in Figure 7. As can be seen from Figure 7, the ion density at the edge of wafer 100 is higher than that at the center of wafer 100. When the power of the upper electrode is increased, the ion density at the edge of wafer 100 increases significantly, while the increase in ion density at the center of wafer 100 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 to 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 of wafer 100 to that at the center of wafer 100 can be changed, so as to carry out targeted treatment for different footing morphologies.

[0074] In summary, the process chamber in this invention can not only meet the requirements of free radical etching in BVR process, but 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.

[0075] The technical features of the above embodiments can be combined in any way. In order to make the description concise, 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.

[0076] The above embodiments only illustrate several implementation methods of this specification, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art to which this invention pertains can make several 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 the patent in this specification should be determined by the appended patent application scope. [Simplified Explanation of the Diagram]

[0025] 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. Figure 1 shows a schematic diagram of the structure of the process chamber in an optional embodiment of the present invention; Figure 2 shows a schematic diagram of the positional relationship between the first coil group and the second coil group and the dielectric cylinder in Figure 1; Figure 3 shows a side view of the ion filter in Figure 1; Figure 4 shows a perspective view of the ion filter in Figure 1 from one angle; Figure 5 shows a top view of the ion filter in Figure 1; Figure 6 shows a schematic diagram of the sheath layer distribution when processing a wafer in the process chamber in an optional embodiment of the present invention; Figure 7 shows a simulation diagram of the ion density distribution from the center to the edge of the wafer in the process chamber in an optional embodiment of the present invention.

Claims

1. An ion filter element, comprising: The filter body has a plurality of filter holes; the filter body has a first surface on which the outlet end of each filter hole is located, and the center of the first surface protrudes from the plane on which the edge of the filter body is located along the central axis of the filter body.

2. The ion filter as described in claim 1, wherein, The first surface is conical.

3. The ion filter as described in claim 2, wherein, The filter body is plate-shaped and has a second surface facing away from the first surface, with the inlet end of each filter hole located on the second surface; the second surface is conical.

4. The ion filter as claimed in claim 1, wherein, The acute angle β formed between the first surface and the plane perpendicular to the central axis of the filter body is greater than or equal to 5 degrees and less than or equal to 20 degrees.

5. The ion filter as claimed in claim 1, wherein, It also includes: at least one connecting portion, the connecting portion being connected to the edge of the filter body portion, and the connecting portion extending along the edge of the filter body portion.

6. The ion filter as claimed in claim 5, wherein, The connecting part is one and connected end to end along the edge of the filter body, or the connecting part is multiple and the multiple connecting parts are spaced apart along the edge of the filter body.

7. A process chamber, comprising: cavity, It has a filter port; The ion filter element according to any one of claims 1 to 6, wherein the ion filter element is located at the filter port.

8. The process chamber as described in claim 7, wherein, The cavity includes a first reaction chamber and a second reaction chamber, wherein the second reaction chamber is provided with a wafer carrier device, and the top wall of the second reaction chamber is provided with the filter port; 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 the filter holes of the filter body, and the other end of the first reaction chamber is used to connect to the air intake assembly; the first surface of the filter body is opposite to the bearing surface of the wafer carrier device.

9. The process chamber as described in claim 8, wherein, The filter body is coaxial with the wafer carrier.

10. The process chamber as described in claim 8, wherein, The ratio of the projected area of ​​the first surface 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.

11. The process chamber as described in claim 8, wherein, The distance between the bearing surface of the wafer carrier device and the lower surface of the top wall of the second reaction chamber is the first distance, and the minimum distance between the bearing surface of the wafer carrier device and the first surface 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.

12. The process chamber as described in claim 8 or 11, wherein, The cavity is provided with a medium cylinder and a medium window. The medium cylinder surrounds the first reaction cavity, and the medium window serves as the top wall of the second reaction cavity.

13. The process chamber as claimed in claim 12, wherein, The process chamber also 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. 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.

14. The process chamber as described in claim 13, wherein, 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.

15. The process chamber as claimed in claim 13, wherein, 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.

16. The process chamber as claimed in claim 13, wherein, 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.

17. The process chamber as claimed in claim 13, wherein, 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.

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