Coil structure for generating plasma and semiconductor process apparatus

Abstract

The application provides a coil structure for generating plasma and a semiconductor process equipment, the coil structure comprises at least one coil group, the coil group comprises a first sub-coil group and a second sub-coil group, the first sub-coil group comprises at least one first plane coil located in a first plane perpendicular to an axis of the coil group, and the second sub-coil group comprises at least one second plane coil located in a second plane parallel to the first plane, the first plane coil and the second plane coil are in series, and a normal projection of the second plane coil on the first plane is mirror-symmetric or mirror-asymmetric with the first plane coil. The coil structure for generating plasma and the semiconductor process equipment provided by the application can compensate for the current distribution difference of the coil in the radial direction, improve the uniformity of the distribution of the coupling energy generated under the coil in the radial direction, and thus improve the uniformity of the distribution of the free radical and ion density in the plasma in the radial direction.

Description

Technical Field

[0001] This invention relates to the field of semiconductor processing technology, and more specifically, to a coil structure for generating plasma in a semiconductor process apparatus and the semiconductor process apparatus itself. Background Technology

[0002] Inductively Coupled Plasma (ICP) sources are commonly used in the semiconductor field for dry etching and thin film deposition. ICP sources generate plasma by exciting gas with a high-frequency electromagnetic field produced by a high-frequency current passing through a coil. They can operate at relatively low chamber pressures and feature high plasma density and minimal damage to the workpiece. As feature sizes continue to shrink, the challenges in the fabrication process become increasingly severe. One crucial requirement is the consistency of the plasma source. For ICP sources, the coil distribution plays a critical role in the morphology and uniformity of the etching. Continuous optimization of the radial and angular current distribution uniformity and symmetry is necessary to further enhance the ability of plasma processing equipment to manufacture highly integrated devices.

[0003] Figure 1 This is a schematic diagram of an existing coil structure. Figure 2 This is a schematic diagram of electromagnetic field distribution in existing technology. For example... Figure 1 and Figure 2 As shown, the coil structure includes an inner coil group 11 and an outer coil group 12, both of which consist of two planar coils. The two planar coils are distributed with 180° rotational symmetry relative to their axis. The orthographic projection shape of each planar coil on its radial section is involute, and the number of coil turns is 1.5. The outer ends of the two planar coils of each inner coil group 11 and outer coil group 12 are connected in parallel and electrically connected to the output terminal of the matching device 13. The inner ends of the two planar coils of each inner coil group 11 and outer coil group 12 are connected in parallel and electrically connected to the input terminal of the matching device 13.

[0004] like Figure 2 As shown, taking a single planar coil with an involute shape and 1.5 turns as an example, the involute is located at... Figure 2 The geometric distribution of the left and right parts on both sides of the dashed line shown in the figure is uneven, which leads to the asymmetry of the electromagnetic field distribution on the left and right sides. This results in different currents on the left and right sides of the coil. In the process, this will cause asymmetry in the distribution of free radicals and ion density in the plasma, that is, uneven plasma distribution, which in turn leads to uneven etching of the wafer and has an adverse effect on etching quality or efficiency. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes a coil structure and semiconductor process equipment for generating plasma in a semiconductor process equipment, which is used to compensate for the difference in current distribution of the coil in the radial direction, improve the uniformity of the radial distribution of coupling energy generated below the coil, thereby improving the uniformity of the radial distribution of free radicals and ion density in the plasma.

[0006] To achieve the above objectives, the present invention provides a coil structure for generating plasma in a semiconductor process apparatus. The coil structure includes at least one coil group, the coil group including a first sub-coil group and a second sub-coil group. The first sub-coil group includes at least one first planar coil located in a first plane perpendicular to the axis of the coil group. The second sub-coil group includes at least one second planar coil located in a second plane parallel to the first plane. The first planar coil and the second planar coil are connected in series. The orthographic projection of the second planar coil on the first plane is either mirror-symmetric or mirror-asymmetric with the first planar coil.

[0007] Optionally, the first sub-coil group includes a plurality of first planar coils, the plurality of first planar coils having the same shape and being spaced apart from each other, and the first ends of the plurality of first planar coils being evenly distributed along the circumferential direction of the coil group;

[0008] The second sub-coil group includes a plurality of second planar coils, which are identical in shape and spaced apart from each other. The first ends of the plurality of second planar coils are evenly distributed along the circumferential direction of the coil group.

[0009] Each of the first planar coils corresponds to one of the second planar coils. The first ends of the first planar coils are connected in parallel, the first ends of the second planar coils are connected in parallel, and the second ends of the first planar coils are connected in series with the second ends of the second planar coils, respectively.

[0010] Optionally, the axial spacing between the first sub-coil group and the second sub-coil group is less than or equal to a specified axial spacing, and the orthographic projection of the second planar coil onto the first plane is mirror-symmetrical to the first planar coil; or,

[0011] The axial distance between the first sub-coil group and the second sub-coil group is greater than the specified axial distance, and the orthographic projection of the second planar coil on the first plane is mirror-image asymmetrical with respect to the first planar coil.

[0012] Optionally, the specified axial spacing is 5 mm.

[0013] Optionally, the axial spacing between the first sub-coil group and the second sub-coil group is greater than or equal to 4 mm and less than or equal to 20 mm.

[0014] Optionally, both the first planar coil and the second planar coil are involute-shaped.

[0015] Optionally, the orthographic projection of the second planar coil onto the first plane is a mirror image of the first planar coil;

[0016] The first planar coil and the second planar coil connected in series therewith have at least one difference in the starting radius, number of revolutions, and rate of change of radius of their involutes.

[0017] Optionally, the number of rotations of the involute in one of the first planar coil and the second planar coil connected in series therewith is larger or smaller, to increase or decrease the magnitude of the coupling energy formed below the first planar coil and the second planar coil connected in series therewith; and / or,

[0018] The rate of change of the involute radius of one of the first planar coil and the second planar coil connected in series therewith is larger or smaller, to reduce or increase the density amplitude of the coupling energy formed below the first planar coil and the second planar coil connected in series therewith; and / or,

[0019] The starting radius of the involute of one of the first planar coil and the second planar coil connected in series therewith is larger or smaller, so that the peak of the coupling energy formed below the first planar coil and the second planar coil connected in series therewith moves radially away from or closer to the axis of the coil group.

[0020] Optionally, the number of rotations of the involute of one of the first planar coil and the second planar coil connected in series therewith varies by a range of greater than or equal to -5% and less than or equal to +12% relative to the number of rotations of the involute of the other.

[0021] The rate of change of the involute radius of one of the first planar coil and the second planar coil connected in series therewith varies with the rate of change of the involute radius of the other from a range of greater than or equal to -10% and less than or equal to +30%.

[0022] The starting radius of the involute of one of the first planar coil and the second planar coil connected in series therewith varies by a range greater than or equal to -10% and less than or equal to +10% relative to the starting radius of the involute of the other.

[0023] Optionally, there are N first planar coils, where N is an even number greater than or equal to 2; the N first planar coils are divided into N / 2 pairs of first coils in the circumferential direction of the coil group, each pair of first coils includes two adjacent first planar coils, and a first extension segment is connected between the first ends of the two adjacent first planar coils to connect them in parallel; the first extension segments in the N / 2 pairs of first coils are connected in parallel.

[0024] There are N second planar coils; the N second planar coils are divided into N / 2 pairs of second coils in the circumferential direction of the coil group. Each pair of second coils includes two adjacent second planar coils, and a second extension section is connected between the first ends of the two adjacent second planar coils to connect them in parallel; the second extension sections in the N / 2 pairs of second coils are connected in parallel.

[0025] Optionally, N is greater than or equal to 6 and less than or equal to 10.

[0026] Optionally, a connecting segment is provided between the second end of each of the first planar coils and the second end of the corresponding second planar coil to connect them in series, wherein the extending direction of the connecting segment is parallel to the axis of the coil group.

[0027] Optionally, there are multiple coil groups, each with a different size, nested together.

[0028] As another technical solution, the present invention also provides a semiconductor process apparatus, including a radio frequency source, a reaction chamber, and the coil structure provided by the present invention, wherein a dielectric window is provided on the top of the reaction chamber, and the coil structure is disposed above the dielectric window; the radio frequency source is used to provide radio frequency power to the coil structure.

[0029] Optionally, the coil structure adopts the coil structure described in any one of claims 2-13;

[0030] The plasma processing equipment further includes a connection structure, which includes a first connector and a second connector, wherein the first connector is electrically connected to a first end of a plurality of first planar coils in the first sub-coil group; and the second connector is electrically connected to a first end of a plurality of second planar coils in the second sub-coil group.

[0031] One of the first connector and the second connector is electrically connected to the input terminal of the radio frequency source, and the other of the first connector and the second connector is electrically connected to the output terminal of the radio frequency source.

[0032] Optionally, the coil structure adopts the coil structure described in claim 10 or 11;

[0033] The first connector includes N / 2 first connecting strips, one end of each of the N / 2 first connecting strips being electrically connected to the first extension section of each of the N / 2 pairs of first coils, and the other ends of the N / 2 first connecting strips converging at a first height position above the first plane and being electrically connected; the second connector includes N / 2 second connecting strips, one end of each of the N / 2 second connecting strips being electrically connected to the second extension section of each of the N / 2 pairs of second planar coils, and the other ends of the N / 2 second connecting strips converging at a second height position above the first plane and being electrically connected, and there is a height difference between the second height position and the first height position.

[0034] Optionally, one end of each of the first connecting strips is electrically connected to the first extension segment at the midpoint of the corresponding first extension segment; and one end of each of the second connecting strips is electrically connected to the second extension segment at the midpoint of the corresponding second extension segment.

[0035] The beneficial effects of this invention are:

[0036] The present invention provides a coil structure for generating plasma in a semiconductor process apparatus, comprising at least one coil group, which includes a first sub-coil group and a second sub-coil group. The first sub-coil group includes at least one first planar coil located in a first plane perpendicular to the axis of the coil group, and the second sub-coil group includes at least one second planar coil located in a second plane parallel to the first plane. The first and second planar coils are connected in series, and the orthographic projection of the second planar coil on the first plane is either mirror-symmetric or mirror-asymmetric with the first planar coil. By making the orthographic projection of the second planar coil on the first plane mirror-symmetric or mirror-asymmetric with the first planar coil, the magnetic and electric fields generated by the first and second sub-coil groups can compensate for each other, ultimately making the total magnetic and electric field distributions mirror-symmetric. This compensates for the radial current distribution difference of the coils, improves the radial uniformity of the coupling energy generated below the coils, and thus improves the radial uniformity of the free radical and ion density distribution in the plasma.

[0037] The semiconductor process equipment provided by the present invention, by adopting the above-mentioned coil structure provided by the present invention, can compensate for the difference in current distribution in the radial direction of the coil, improve the uniformity of the radial distribution of coupling energy generated below the coil, thereby improving the uniformity of the radial distribution of free radicals and ion density in the plasma. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of an existing coil structure;

[0039] Figure 2 This is a schematic diagram of electromagnetic field distribution in the prior art;

[0040] Figure 3A This is a schematic diagram of the orthographic projection of a single first planar coil and a second planar coil connected in series with it on a first plane, as used in the first embodiment of the present invention.

[0041] Figure 3B for Figure 3A A schematic diagram of the orthographic projection of the mirror image of a single first planar coil and a second planar coil connected in series with it onto a first plane;

[0042] Figure 4 This is a schematic diagram of the parameters of an involute.

[0043] Figure 5A This is a schematic diagram of the orthographic projection of the mirror image of a single first planar coil and a second planar coil connected in series with it, as used in the first embodiment of the present invention, onto a first plane.

[0044] Figure 5B This is a schematic diagram of the orthographic projection of the mirror image of the third type of single first planar coil and the second planar coil connected in series therewith in the first embodiment of the present invention onto the first plane.

[0045] Figure 5C This is a schematic diagram of the orthographic projection of the fourth type of single first planar coil and second planar coil connected in series with it on a first plane, as used in the first embodiment of the present invention.

[0046] Figure 5D This is a schematic diagram of the orthographic projection of the mirror image of a single first planar coil and a second planar coil connected in series with it in the first embodiment of the present invention onto a first plane.

[0047] Figure 6A for Figure 5C A comparison of the coupling energy distribution curves of the fourth type of single first planar coil and the second planar coil connected in series with it when the number of coil turns is different;

[0048] Figure 6B for Figure 5B A comparison of the coupling energy distribution curves of the third type of single first planar coil and the second planar coil connected in series with it when the radius change rate is different;

[0049] Figure 6C for Figure 5D A comparison of the coupling energy distribution curves of the fifth type of single first planar coil and the second planar coil connected in series with it when the initial radii are different;

[0050] Figure 7 for Figure 1 The projection of the coil structure in the image onto its radial section;

[0051] Figure 8 This is a schematic diagram of the coil structure provided in the second embodiment of the present invention;

[0052] Figure 9A This is a schematic diagram of the orthographic projection of the first sub-coil group used in the third embodiment of the present invention onto the first plane;

[0053] Figure 9B This is a schematic diagram of the orthographic projection of the first sub-coil group and the second sub-coil group used in the third embodiment of the present invention onto a first plane;

[0054] Figure 10A for Figure 9A A schematic diagram of the orthographic projection of the first ends of multiple first planar coils connected in parallel in the coil structure;

[0055] Figure 10B for Figure 9A A three-dimensional diagram of the first ends of multiple first planar coils connected in parallel in the coil structure;

[0056] Figure 11 for Figure 8 A three-dimensional diagram showing the electrical connection of multiple first planar coils and multiple second planar coils in the coil structure;

[0057] Figure 12 A perspective view of another coil structure provided in the second embodiment of the present invention;

[0058] Figure 13 This is a schematic diagram of the structure of the plasma processing equipment provided in the third embodiment of the present invention. Detailed Implementation

[0059] To enable those skilled in the art to better understand the technical solution of the present invention, the coil structure for generating plasma and the semiconductor process equipment provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0060] First Embodiment

[0061] This embodiment provides a coil structure for generating plasma in a semiconductor process apparatus. The semiconductor process apparatus can be used to perform etching processes on wafers. The coil structure serves as the upper electrode to excite the process gas in the reaction chamber to form plasma.

[0062] The coil structure includes at least one coil group, which comprises a first sub-coil group and a second sub-coil group. The first sub-coil group includes at least one first planar coil located in a first plane perpendicular to the axis of the coil group. The second sub-coil group includes at least one second planar coil located in a second plane parallel to the first plane. The first and second planar coils are connected in series. The orthographic projection of the second planar coil onto the first plane is either mirror-symmetrical or mirror-asymmetrical with respect to the first planar coil. The second plane is, for example, located at a certain interval below the first plane containing the first planar coil.

[0063] A mirror image refers to a situation where the orthographic projection of the first planar coil onto the first plane (hereinafter referred to as first projection A) and the orthographic projection of the second planar coil onto the first plane (hereinafter referred to as second projection B) have the same or similar shapes, but are arranged in opposite directions. Specifically, both first projection A and second projection B have two sides parallel to the first plane, one frontal shape and the other backal shape. Symmetry refers to a situation where all parameters of the frontal shape of one of the first projections A and the other backal shape are identical. Asymmetry refers to a situation where the frontal shape of one of the first projections A and the other backal shape are similar, but some parameters are different.

[0064] For example, please see Figure 3A The first and second planar coils are both involute-shaped, with the first planar coil having a first involute shape 31 and the second planar coil having a second involute shape 32. The projection of the second involute shape 32 onto the first plane is a mirror image of the first involute shape 31. Specifically, as... Figure 4 As shown, the rotation center of the involute is point O, the starting point is C0, the starting radius is R0, the ending point is C1, and the ending radius is R1. In this embodiment, at least one of the starting radius, number of rotations, and radius change rate of the first involute 31 and the second involute 32 is different to achieve mirror-image asymmetry between the two.

[0065] For example, such as Figure 3B As shown, for ease of comparison, Figure 3A The front and back sides of one of the first involute 31 and the second involute 32 are reversed, that is, Figure 3B One of the first involute 31 and the second involute 32 is a mirror image. A comparison reveals that... Figure 3BThe first involute 31 and the second involute 32 in the diagram start at the same point and have the same initial radius. However, the first involute 31 has a greater number of rotations than the second involute 32, and the rate of change of the radius of the first involute 31 is less than that of the second involute 32. Therefore, the first involute 31 and the second involute 32 have different numbers of rotations and different rates of radius change, thus achieving a mirror-image asymmetry between them.

[0066] In some alternative embodiments, the second end 312 of the first planar coil is connected in series with the second end 322 of the second planar coil, thereby realizing the series connection of the first planar coil and the second planar coil.

[0067] By making the orthographic projection of the second planar coil on the first plane mirror-symmetric or mirror-asymmetric with that of the first planar coil, the magnetic and electric fields generated by the first and second planar coils can compensate for each other, ultimately making the total magnetic and electric field distributions of the two mirror-symmetric. This can compensate for the difference in current distribution in the radial direction of the coils, improve the uniformity of the radial distribution of coupling energy generated below the coils, and thus improve the uniformity of the radial distribution of free radicals and ion density in the plasma.

[0068] In some preferred embodiments, both the first planar coil and the second planar coil are involute-shaped, such as a spiral involute or a polygonal (e.g., a square) involute. Of course, in practical applications, the first and second planar coils can also be any other shape, such as an arc.

[0069] The axial spacing between the first and second sub-coil groups depends on the power output of the upper electrode power supply. For example, if the power output of the upper electrode power supply is in the medium to low power range (generally <2000W), the axial spacing can be set in a smaller range. If the power output of the upper electrode power supply is in the high power range (generally ≥2000W), the axial spacing should be set in a larger range to avoid arcing between the first and second sub-coil groups due to excessive distance. However, the axial spacing should not be too large, otherwise the compensation effect for the difference in current distribution between the first and second sub-coil groups will fail.

[0070] In some preferred embodiments, the axial spacing between the first sub-coil group and the second sub-coil group is greater than or equal to 4 mm and less than or equal to 20 mm. By setting the axial spacing within this range, arcing caused by excessive distance between the first and second sub-coil groups can be avoided, and compensation for differences in current distribution between the first and second sub-coil groups can be achieved.

[0071] In some alternative embodiments, the axial spacing specified above is 5 mm.

[0072] In some optional embodiments, if the axial distance between the first sub-coil group and the second sub-coil group is less than or equal to a specified axial distance (e.g., 5 mm), then the first projection A and the second projection B are mirror-symmetrical. For cases with a small axial distance, the mirror-symmetry of the first projection A and the second projection B can compensate for differences in current distribution between the first and second sub-coil groups.

[0073] However, if the axial distance between the first sub-coil group and the second sub-coil group is greater than the specified axial distance, the compensation effect may be insufficient. In this case, the first projection A and the second projection B can be made to be mirror images and asymmetrical, which can enhance the compensation effect.

[0074] It should be noted that, Figure 3A and Figure 3B Only one example of a first planar coil and a second planar coil achieving mirror-image asymmetry between the first projection A and the second projection B is shown. However, the present invention is not limited to this. In practical applications, the mirror-image asymmetry between the first projection A and the second projection B can be achieved by making at least one of the starting radius, number of rotations, and radius change rate of the involute of the first planar coil and the second planar coil connected in series different. The following are examples of cases where at least one of the starting radius, number of rotations, and radius change rate of the first involute 31 of the first planar coil and the second involute 32 of the second planar coil connected in series is different.

[0075] like Figure 5A As shown, the starting points of the first involute 31 and the second involute 32 coincide, and their starting radii are the same. However, the number of rotations of the first involute 31 is less than the number of rotations of the second involute 32, and the rate of change of the radius of the first involute 31 is less than the rate of change of the radius of the second involute 32.

[0076] like Figure 5B As shown, the starting points of the first involute 31 and the second involute 32 coincide, they have the same starting radius, and the same number of rotations. The rate of change of the radius of the first involute 31 is less than the rate of change of the radius of the second involute 32.

[0077] like Figure 5C As shown, the starting points of the first involute 31 and the second involute 32 coincide, the starting radii are the same, the rate of change of the radius is the same, and the number of rotations of the first involute 31 is less than the number of rotations of the second involute 32.

[0078] like Figure 5DAs shown, the starting points of the first involute 31 and the second involute 32 do not coincide, but they have the same rate of change of radius and the same number of rotations. The starting radius of the first involute 31 is greater than that of the second involute 32.

[0079] Figure 6A for Figure 5C A comparison of the coupling energy distribution curves of the fourth type of single first planar coil and the second planar coil connected in series with it when the number of coil turns is different. Figure 6A The horizontal axis represents the radial radius of the reaction chamber (i.e., the radial direction of the coil assembly); the vertical axis represents the magnitude of the coupling energy. Curve S1 is the coupling energy curve formed below the first planar coil corresponding to the first involute 31; curve S2 is the coupling energy curve formed below the second planar coil corresponding to the second involute 32. Figure 5C As shown, the number of rotations of the second involute 32 (0.9 turns) is larger than that of the first involute 31 (0.75 turns). In this case, the effective length of the second planar coil is greater than that of the first planar coil, resulting in a larger coverage area of ​​curve S2 compared to curve S1. Consequently, the coupling energy formed below the second planar coil is greater than that formed below the first planar coil, although the peak value of the coupling energy formed below the second planar coil is slightly smaller than that of the first planar coil. Therefore, by increasing or decreasing the number of rotations of the involute in either the first planar coil or the second planar coil connected in series with it, the magnitude of the coupling energy formed below either the first planar coil or the second planar coil connected in series with it can be increased or decreased, thereby compensating for differences in current distribution. In practical applications, the number of rotations of the involute in either the first planar coil or the second planar coil connected in series with it can be adjusted individually, or the number of rotations of the involute in both the first planar coil and the second planar coil connected in series with it can be adjusted simultaneously.

[0080] In some optional embodiments, the number of rotations of the involute of one of the first planar coil and the second planar coil connected in series therewith varies by a range greater than or equal to -5% and less than or equal to +12% relative to the number of rotations of the involute of the other. Here, the symbol "-" indicates a decrease; the symbol "+" indicates an increase.

[0081] Figure 6B for Figure 5B A comparison of the coupling energy distribution curves of the third type of single first planar coil and the second planar coil connected in series with it when the radius change rate is different. Figure 6BThe horizontal axis represents the radial radius of the reaction chamber; the vertical axis represents the magnitude of the coupling energy. Curve S1 is the coupling energy curve formed below the first planar coil corresponding to the first involute 31; curve S2 is the coupling energy curve formed below the second planar coil corresponding to the second involute 32. For example... Figure 5B As shown, the radius change rate of the first involute 31 (70 mm / turn) is smaller than that of the second involute 32 (90 mm / turn). In this case, the first planar coil will become more compact in its radial direction relative to the second planar coil, thereby resulting in a larger amplitude of the coupling energy density formed below the first planar coil 21. Figure 6B As shown, curve S1 has a larger coupling energy density amplitude compared to curve S2. Therefore, by increasing or decreasing the rate of change of the involute radius of either the first planar coil or the second planar coil connected in series with it, the coupling energy density amplitude formed beneath either the first planar coil or the second planar coil connected in series with it can be decreased or increased, thereby compensating for differences in current distribution. In practical applications, the rate of change of the involute radius of either the first planar coil or the second planar coil connected in series with it can be adjusted individually, or both rates of change can be adjusted simultaneously.

[0082] In some alternative embodiments, the rate of change of the involute radius of one of the first planar coil and the second planar coil connected in series therewith varies with respect to the rate of change of the involute radius of the other within a range greater than or equal to -10% and less than or equal to +30%.

[0083] Figure 6C for Figure 5D A comparison of the coupling energy distribution curves of the fifth type of single first planar coil and the second planar coil connected in series with it when the initial radii are different. Figure 6C The horizontal axis represents the radial radius of the reaction chamber; the vertical axis represents the magnitude of the coupling energy. Curve S1 is the coupling energy curve formed below the first planar coil corresponding to the first involute 31; curve S2 is the coupling energy curve formed below the second planar coil corresponding to the second involute 32. For example... Figure 5DAs shown, the initial radius of the first involute 31 (150 mm) is greater than the initial radius of the second involute 32 (120 mm). In this case, the larger the initial radius of the involute, the closer the peak of the coupling energy is to the position with a larger radial radius of the reaction chamber. This makes the peak of the coupling energy of curve S1 closer to the position with a larger radial radius of the reaction chamber than curve S2. Therefore, by increasing or decreasing the initial radius of the involute of either the first planar coil or the second planar coil connected in series with it, the peak of the coupling energy formed below either the first planar coil or the second planar coil connected in series with it can be moved radially away from or closer to the axis of the coil group (i.e., the radial direction of the reaction chamber) along the coil group, thereby compensating for differences in current distribution. In practical applications, the initial radius of the involute of either the first planar coil or the second planar coil connected in series with it can be adjusted individually, or the initial radii of the involute of both the first planar coil and the second planar coil connected in series with it can be adjusted simultaneously.

[0084] In some alternative embodiments, the starting radius of the involute of one of the first planar coil and the second planar coil connected in series therewith varies by a range greater than or equal to -10% and less than or equal to +10% relative to the starting radius of the involute of the other of the first planar coil and the second planar coil connected in series therewith.

[0085] It should be noted that in practical applications, the first and second planar coils can also be any other shape, such as an arc. In this case, the relevant parameters of the shape can be adjusted according to the characteristics of different shapes, as long as they can compensate for the difference in current distribution.

[0086] Second Embodiment

[0087] For example Figure 1 The coil structure shown has an asymmetry in its radial cross-section projection shape in the circumferential direction (i.e., angular direction). Specifically, as shown... Figure 7 As shown, the radial section is divided into four quadrant regions (I, II, III, IV). As the radius of the involute of each planar coil gradually increases as it extends from the inner end to the outer end, there is a significant difference between the coil structure in the first quadrant region I and the third quadrant region III and the coil structure in the second quadrant region II and the fourth quadrant region IV. This leads to differences in the current distribution of the coil structure in the circumferential direction (i.e., angular direction), resulting in uneven electromagnetic field distribution. During the process, this causes asymmetry in the distribution of free radicals and ions in the plasma, which in turn causes uneven angular distribution of plasma density, ultimately affecting the uniformity of the process.

[0088] To address the aforementioned technical problems, this embodiment improves the coil structure based on the first embodiment described above. For details, please refer to... Figure 8 The first sub-coil group includes multiple first planar coils 21, all located within the aforementioned first plane. The multiple first planar coils 21 have the same shape and are spaced apart from each other. The first ends 211 of the multiple first planar coils 21 are evenly distributed along the circumferential direction of the coil group. The second sub-coil group includes multiple second planar coils 22, all of the same shape and spaced apart from each other. The first ends 221 of the multiple second planar coils 22 are evenly distributed along the circumferential direction of the coil group. Furthermore, the multiple first planar coils 21 correspond one-to-one with the multiple second planar coils 22. The first ends 211 of the multiple first planar coils 21 are connected in parallel, the first ends 221 of the multiple second planar coils 22 are connected in parallel, and the second ends 212 of the multiple first planar coils 21 are connected in series with the second ends 222 of the multiple second planar coils 22.

[0089] Specifically, such as Figure 9A As shown, taking multiple first planar coils 21 as an example, the multiple first planar coils 21 have the same shape, for example, all of them are involute-shaped, and among the first ends 211 of the multiple first planar coils 21, there is a gap between any two adjacent first ends 211 in the circumferential direction of the coil group. In other words, after rotating a certain angle (the central angle corresponding to the above gap) around the axis of the coil group clockwise or counterclockwise, the first end 211 of any one first planar coil 21 will coincide with the first end 211 of another adjacent first planar coil 21. For example, Figure 9A The diagram shows eight first planar coils 21, in which the first end 211 of any one first planar coil 21 will coincide with the first end 211 of the adjacent first planar coil 21 after rotating 45° clockwise or counterclockwise around the axis of the coil group.

[0090] Since the multiple first planar coils 21 have the same shape and can be evenly distributed along the circumferential direction of the coil group, the multiple first planar coils 21 have angular symmetry in the circumferential direction of the coil group, that is, they are symmetrical in the circumferential direction of the coil group. This can avoid differences in current distribution in the circumferential direction, thereby improving the angular distribution uniformity of plasma density and improving process uniformity.

[0091] The more first planar coils 21 there are in the same coil group, the better the angular symmetry of the projection formed by the multiple first planar coils 21 on the first plane, which is more conducive to improving the angular distribution symmetry of plasma density. In some preferred embodiments, the number of first planar coils 21 is greater than or equal to 6 and less than or equal to 10.

[0092] Similar to the first planar coil 21 described above, multiple second planar coils 22 are all located within a second plane and have the same shape, such as involutes. These multiple second planar coils 22 also exhibit angular symmetry in the circumferential direction of the coil group, thereby avoiding differences in current distribution in the circumferential direction and improving the angular uniformity of plasma density distribution, thus enhancing process uniformity.

[0093] Furthermore, the first ends 221 of the plurality of second planar coils 22 are connected in parallel, and the second ends 212 of the plurality of first planar coils 21 are connected in series with the second ends 222 of the plurality of second planar coils 22. In this case, one of the first ends 221 of the plurality of second planar coils 22 and the first ends 211 of the plurality of first planar coils 21 is used as an RF feed terminal and electrically connected to the output terminal of the RF source, and the other is used as an RF feed terminal and electrically connected to the input terminal of the RF source.

[0094] like Figure 9B As shown, the orthographic projection of the first sub-coil group, composed of multiple first planar coils 21, on the first plane is the third projection C; the orthographic projection of the second sub-coil group, composed of multiple second planar coils 22, on the first plane is the fourth projection D. The third projection C and the fourth projection D are either mirror-symmetric or mirror-asymmetric. In this way, the magnetic and electric fields generated by the first and second sub-coil groups can compensate for each other, ultimately making the total magnetic and electric field distributions of the two groups mirror-symmetric. This can compensate for the difference in current distribution in the radial direction of the coils, improve the radial uniformity of the coupling energy generated below the coils, and thus improve the radial uniformity of the free radical and ion density distribution in the plasma.

[0095] In some optional embodiments, the first ends 211 of the plurality of first planar coils 21 are connected in parallel and the first ends 221 of the plurality of second planar coils 22 are connected in parallel in various ways, for example, as follows: Figure 10A and Figure 10B As shown, taking the parallel connection of the first ends 211 of multiple first planar coils 21 as an example, assuming there are N first planar coils 21, where N is an even number greater than or equal to 2, for example, N is greater than or equal to 6 and less than or equal to 10. Figure 10A In the middle, N = 8. The N first planar coils 21 are divided into N / 2 pairs of first coil pairs along the circumferential direction of the coil group, for example... Figure 10A The eight first planar coils 21 are divided into four pairs (two in a pair). Each pair includes two adjacent first planar coils (21a, 21b), and a first extension segment 23 connects the first ends (211a, 211b) of the two adjacent first planar coils (21a, 21b) to connect them in parallel. Furthermore, the first extension segments 23 in the N / 2 pairs of first coils are connected in parallel, for example, as shown below. Figure 10BAs shown, the first extension segments 23 of the first coil pair N / 2 are connected in parallel through the connection structure 4.

[0096] In some alternative embodiments, such as Figure 10B As shown, the midpoint of each first extension segment 23 is used as an RF feed point or an RF feed point. This ensures that the lengths of two adjacent first planar coils (21a, 21b) are the same, so that the current flows through the first planar coils (21a, 21b) along the same path.

[0097] The parallel connection of the first ends 221 of the multiple second planar coils 22 is the same as the parallel connection of the first ends 211 of the multiple first planar coils 21. Specifically, there are N second planar coils 22; the N second planar coils 22 are divided into N / 2 pairs of second coil pairs in the circumferential direction of the coil group. Each pair of second coil pairs includes two adjacent second planar coils 22, and a second extension segment is connected between the first ends 221 of the two adjacent second planar coils 22 to connect them in parallel; the second extension segments in the N / 2 pairs of second coil pairs are connected in parallel.

[0098] It should be noted that the parallel connection of the first ends 221 of the multiple second planar coils 22 and the parallel connection of the first ends 211 of the multiple first planar coils 21 can also be any other method. For example, the first ends 211 of the multiple first planar coils 21 can be directly connected in parallel, and the first ends 221 of the multiple second planar coils 22 can be directly connected in parallel.

[0099] In some optional embodiments, the second ends 212 of the plurality of first planar coils 21 can be connected in series with the second ends 222 of the plurality of second planar coils 22 in various ways, for example, as follows: Figure 8 As shown, a connecting segment 24 is connected between the second end 212 of each first planar coil 21 and the second end 222 of the corresponding second planar coil 22 to connect the two in series. The extension direction of the connecting segment 24 is parallel to the axis of the coil group.

[0100] In some alternative embodiments, such as Figure 11As shown, the coil group includes a set of first sub-coil groups and second sub-coil groups, which are spaced apart along the axis of the coil group. The first sub-coil group includes multiple first planar coils 21 located in the first plane, and the second sub-coil group includes multiple second planar coils 22 located in a second plane parallel to the first plane. Different first extension sections 23 in the first sub-coil group are connected in parallel via first connectors 41 in the connection structure 4; different second extension sections 25 in the second sub-coil group are connected in parallel via second connectors 42 in the connection structure 4; and the second end of each first planar coil 21 and the second end of its corresponding second planar coil 22 are connected in series via a connecting section 24. One of the first connectors 41 and the second connector 42 is used for electrical connection to the input terminal of the RF source, and the other is used for electrical connection to the output terminal of the RF source.

[0101] In some alternative embodiments, Figure 12 Another coil structure 2' is shown, which differs from the coil structure 2 described above in that it includes two sets of coil groups (2a, 2b) with different dimensions, nested together. The two sets of coil groups (2a, 2b) are respectively positioned at different diameter circumferences within the reaction chamber of the semiconductor process equipment. For example, coil group 2a is arranged around the periphery of coil group 2b, with the two sets of coil groups (2a, 2b) corresponding to the central and edge regions of the reaction chamber, respectively. This improves the radial uniformity of plasma distribution within the reaction chamber. Of course, in practical applications, there can be three or four or more sets of coil groups; this embodiment of the invention does not impose any particular limitation on this.

[0102] In summary, the coil structure for generating plasma in a semiconductor process apparatus provided by this invention includes at least one coil group, comprising a first sub-coil group and a second sub-coil group. The first sub-coil group includes at least one first planar coil located in a first plane perpendicular to the axis of the coil group, and the second sub-coil group includes at least one second planar coil located in a second plane parallel to the first plane. The first and second planar coils are connected in series, and the orthographic projection of the second planar coil onto the first plane is either mirror-symmetrical or mirror-asymmetric with the first planar coil. By making the orthographic projection of the second planar coil onto the first plane mirror-symmetrical or mirror-asymmetric with the first planar coil, the magnetic and electric fields generated by the first and second sub-coil groups can compensate for each other, ultimately making the total magnetic and electric field distributions mirror-symmetrical. This compensates for differences in current distribution in the radial and angular directions of the coils, improves the uniformity of the coupling energy distribution generated below the coils, and thus improves the uniformity of the distribution of free radicals and ion density in the plasma.

[0103] Third Embodiment

[0104] As another technical solution, this embodiment also provides a semiconductor process apparatus, for example, such as... Figure 13 As shown, the semiconductor process equipment includes a radio frequency source 105 with an upper electrode, a reaction chamber 100, and a coil structure 2'. A dielectric window 101 is disposed at the top of the reaction chamber 100, and the coil structure 2' is disposed above the dielectric window 101. The coil structure 2' employs the coil structure provided in the above embodiments of the present invention, for example, using... Figure 12 The coil structure 2' shown is illustrated.

[0105] Radio frequency (RF) source 105 provides RF power to coil structure 2' to excite the process gas in reaction chamber 100 to form plasma. RF source 105 may include, for example, an RF power supply and a matching circuit, or may only include an RF power supply. Furthermore, a base 102 is provided in reaction chamber 100 for supporting the wafer, and this base 102 is electrically connected to the RF source 103 at the lower electrode. The RF source 103 applies an RF bias voltage to the base 102 to attract the plasma towards the wafer surface.

[0106] In some alternative embodiments, the coil structure adopts the coil structure of the second embodiment described above, for example... Figure 11 or Figure 12 The coil structure in the above-mentioned semiconductor process equipment further includes a connection structure 4, which includes a first connector 41 and a second connector 42. The first connector 41 is electrically connected to the first ends 211 of the plurality of first planar coils 21 in the first sub-coil group, thereby realizing the parallel connection of the first ends 211 of the plurality of first planar coils 21. The second connector 42 is used to electrically connect the first ends 221 of the plurality of second planar coils 22 in the second sub-coil group, thereby realizing the parallel connection of the first ends 221 of the plurality of second planar coils 22. Furthermore, one of the first connector 41 and the second connector 42 is electrically connected to the input terminal of the radio frequency source 105, and the other of the first connector 41 and the second connector 42 is electrically connected to the output terminal of the radio frequency source 105.

[0107] In some alternative embodiments, the coil structure employs... Figure 11 or Figure 12 The coil structure in the example. In this case, such as... Figure 11 and Figure 12 As shown, the first connector 41 includes N / 2 first connecting strips, for example... Figure 11 and Figure 12Four first connecting strips are shown. One end of each of the N / 2 first connecting strips is electrically connected to the first extension 23 of the N / 2 pairs of first coils, and the other ends of the N / 2 first connecting strips converge at a first height position above the first plane and are electrically connected. This convergence point is used as the connection position for electrical connection with the input or output terminal of the radio frequency source 105.

[0108] Similarly, the second connector 42 includes N / 2 second connecting strips, one end of each of the N / 2 second connecting strips is electrically connected to the second extension segment 25 of the N / 2 pairs of second planar coils, and the other ends of the N / 2 second connecting strips converge at a second height position above the first plane and are electrically connected thereto. The second height position has a height difference with the first height position to ensure that the first connector 41 and the second connector 42 do not come into contact.

[0109] In some optional embodiments, the midpoint of each first extension segment 23 is used as an RF feed point or an RF feed point, and the midpoint of each second extension segment 25 is used as an RF feed point or an RF feed point. In this way, it can be ensured that the lengths of two adjacent first planar coils 21 and two adjacent second planar coils 22 are the same, so that the paths of current flowing through each first planar coil 21 and each second planar coil 22 are the same.

[0110] The semiconductor process equipment provided by the present invention, by adopting the above-mentioned coil structure provided by the present invention, can compensate for the difference in current distribution of the coil in the radial and angular directions, improve the uniformity of the distribution of coupling energy generated below the coil, and thereby improve the uniformity of the distribution of free radicals and ion density in the plasma.

[0111] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A coil structure for generating plasma in a semiconductor process apparatus, characterized in that, The coil structure includes at least one coil group, the coil group includes a first sub-coil group and a second sub-coil group, the first sub-coil group includes at least one first planar coil located in a first plane perpendicular to the axis of the coil group, the second sub-coil group includes at least one second planar coil located in a second plane parallel to the first plane, the first planar coil and the second planar coil are connected in series, and the orthographic projection of the second planar coil on the first plane is a mirror image of the first planar coil. The mirror image refers to the fact that the orthographic projection of the first planar coil onto the first plane and the orthographic projection of the second planar coil onto the first plane have the same or similar shape, but are arranged in opposite directions. The asymmetry refers to the fact that the frontal shape of one of the orthographic projections of the first planar coil on the first plane and the second planar coil on the first plane is similar to the reverse shape of the other of the orthographic projections of the first planar coil on the first plane and the second planar coil on the first plane, but some parameters are different.

2. The coil structure according to claim 1, characterized in that, The first sub-coil group includes a plurality of first planar coils, the plurality of first planar coils having the same shape and being spaced apart from each other, and the first ends of the plurality of first planar coils being evenly distributed along the circumferential direction of the coil group; The second sub-coil group includes a plurality of second planar coils, which are identical in shape and spaced apart from each other. The first ends of the plurality of second planar coils are evenly distributed along the circumferential direction of the coil group. Each of the first planar coils corresponds to one of the second planar coils. The first ends of the first planar coils are connected in parallel, the first ends of the second planar coils are connected in parallel, and the second ends of the first planar coils are connected in series with the second ends of the second planar coils, respectively.

3. The coil structure according to claim 1 or 2, characterized in that, The axial distance between the first sub-coil group and the second sub-coil group is greater than the specified axial distance.

4. The coil structure according to claim 3, characterized in that, The specified axial spacing is 5 mm.

5. The coil structure according to claim 2, characterized in that, The axial spacing between the first sub-coil group and the second sub-coil group is greater than or equal to 4 mm and less than or equal to 20 mm.

6. The coil structure according to claim 2, characterized in that, Both the first planar coil and the second planar coil are involute-shaped.

7. The coil structure according to claim 6, characterized in that, The first planar coil and the second planar coil connected in series therewith have at least one difference in the starting radius, number of revolutions, and rate of change of radius of their involutes.

8. The coil structure according to claim 7, characterized in that, The number of rotations of the involute in one of the first planar coil and the second planar coil connected in series therewith is larger or smaller, to increase or decrease the magnitude of the coupling energy formed below the first planar coil and the second planar coil connected in series therewith; and / or, The rate of change of the involute radius of one of the first planar coil and the second planar coil connected in series therewith is larger or smaller, to reduce or increase the density amplitude of the coupling energy formed below the first planar coil and the second planar coil connected in series therewith; and / or, The starting radius of the involute of one of the first planar coil and the second planar coil connected in series therewith is larger or smaller, so that the peak of the coupling energy formed below the first planar coil and the second planar coil connected in series therewith moves radially away from or closer to the axis of the coil group.

9. The coil structure according to claim 8, characterized in that, The number of rotations of the involute of one of the first planar coil and the second planar coil connected in series therewith varies within the range of greater than or equal to -5% and less than or equal to +12% relative to the number of rotations of the involute of the other. The rate of change of the involute radius of one of the first planar coil and the second planar coil connected in series therewith varies with the rate of change of the involute radius of the other within a range greater than or equal to -10% and less than or equal to +30%. The starting radius of the involute of one of the first planar coil and the second planar coil connected in series therewith varies by a range of greater than or equal to -10% and less than or equal to +10% relative to the starting radius of the involute of the other.

10. The coil structure according to claim 2, characterized in that, The first planar coil consists of N coils, where N is an even number greater than or equal to 2. The N first planar coils are divided into N / 2 pairs of first coils in the circumferential direction of the coil group. Each pair of first coils includes two adjacent first planar coils, and a first extension segment is connected between the first ends of the two adjacent first planar coils to connect them in parallel. The first extension segments in the N / 2 pairs of first coils are connected in parallel. There are N second planar coils; the N second planar coils are divided into N / 2 pairs of second coils in the circumferential direction of the coil group. Each pair of second coils includes two adjacent second planar coils, and a second extension section is connected between the first ends of the two adjacent second planar coils to connect them in parallel; the second extension sections in the N / 2 pairs of second coils are connected in parallel.

11. The coil structure according to claim 10, characterized in that, The N is greater than or equal to 6 and less than or equal to 10.

12. The coil structure according to claim 2, characterized in that, A connecting segment is provided between the second end of each of the first planar coils and the second end of the corresponding second planar coil to connect them in series, and the extension direction of the connecting segment is parallel to the axis of the coil group.

13. The coil structure according to claim 1 or 2, characterized in that, The coil group consists of multiple groups, each with a different size, and they are nested together.

14. A semiconductor process apparatus, characterized in that, The device includes a radio frequency source, a reaction chamber, and a coil structure as described in any one of claims 1-13, wherein a dielectric window is provided at the top of the reaction chamber, and the coil structure is disposed above the dielectric window; the radio frequency source is used to provide radio frequency power to the coil structure.

15. The semiconductor process equipment according to claim 14, characterized in that, The coil structure adopts the coil structure described in any one of claims 2-13; The semiconductor process equipment further includes a connection structure, which includes a first connector and a second connector, wherein the first connector is electrically connected to a first end of a plurality of first planar coils in the first sub-coil group; and the second connector is electrically connected to a first end of a plurality of second planar coils in the second sub-coil group. One of the first connector and the second connector is electrically connected to the input terminal of the radio frequency source, and the other of the first connector and the second connector is electrically connected to the output terminal of the radio frequency source.

16. The semiconductor process equipment according to claim 15, characterized in that, The coil structure adopts the coil structure described in claim 10 or 11; The first connector includes N / 2 first connecting strips, one end of each of the N / 2 first connecting strips being electrically connected to the first extension section of each of the N / 2 pairs of first coils, and the other ends of the N / 2 first connecting strips converging at a first height position above the first plane and being electrically connected; the second connector includes N / 2 second connecting strips, one end of each of the N / 2 second connecting strips being electrically connected to the second extension section of each of the N / 2 pairs of second coils, and the other ends of the N / 2 second connecting strips converging at a second height position above the first plane and being electrically connected, and there is a height difference between the second height position and the first height position.

17. The semiconductor process equipment according to claim 16, characterized in that, One end of each of the first connecting strips is electrically connected to the first extension segment at the midpoint of the corresponding first extension segment; one end of each of the second connecting strips is electrically connected to the second extension segment at the midpoint of the corresponding second extension segment.

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