Plasma Generation Coil Structure and Semiconductor Processing Apparatus

Abstract

The present invention provides a coil structure for plasma generation and a semiconductor processing apparatus. Each coil unit of the coil structure includes M coil groups, where M is an integer of 4 or more. The M coil groups have the same structure and are connected in parallel to each other. The planar coils of each layer of the M coil groups correspond to each other one-to-one and are provided on the same layer. The M planar coils located on the same layer are evenly distributed at intervals in the circumferential direction of the planar coil. The coil groups include N layers of planar coils parallel to each other, where N is an even number of 4 or more. The N layers of planar coils are provided at intervals along a direction perpendicular to the plane in which the planar coils are located, and are connected in series end-to-end in sequence. The orthographic projections of the planar coils of each adjacent two layers on the plane in which the planar coils are located are mirror-symmetric.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor processing, and more specifically, to a coil structure for generating plasma in a semiconductor process apparatus and a semiconductor process apparatus.

Background Art

[0002] An inductively coupled plasma (ICP) source is a plasma source commonly used for dry etching and thin film deposition in the semiconductor field. The ICP source generates plasma by exciting gas with a high-frequency electromagnetic field generated when a high-frequency current passes through a coil, and can operate under a low chamber pressure. It has characteristics such as a high plasma density and low damage to the workpiece. As the critical dimensions become smaller day by day, the challenges faced in the process of processing also become increasingly severe. One of the very important requirements is the consistency of the plasma source. In the case of the ICP source, the coil distribution plays an important role in the form of etching and its uniformity. It is necessary to continuously optimize the uniform symmetry of the radial and angular distributions of the coil current, thereby further enhancing the ability of the process to manufacture highly integrated devices of the plasma processing apparatus.

[0003] FIG. 1 is a schematic diagram of a conventional coil structure. FIG. 2A is a projection view of the coil structure in FIG. 1 in the radial cross-section. As shown in FIGS. 1 and 2A, the coil structure includes an inner coil group 11 and an outer coil group 12, both of which are composed of two planar coils. The two planar coils are distributed in a 180° rotational symmetry with respect to their axial directions. The shape of the orthographic projection of each planar coil in the radial cross-section is involute, and the number of turns of the coil is 1.5 turns. The outer ends located on the outer rings of the two planar coils of the inner coil group 11 and the outer coil group 12 are connected in parallel and electrically connected to the output end of the matcher 13, and the inner ends located on the inner rings are connected in parallel and electrically connected to the input end of the matcher 13.

[0004] As shown in FIG. 2A, taking as an example that the shape of one planar coil is involute and the involute has 1.5 turns, due to the unequal geometric distribution of the left and right parts located on both sides of the dashed line shown in FIG. 2A of the involute, it causes an asymmetric distribution of the electromagnetic field on the left and right, and further causes different currents on the left and right of the coil. This causes an asymmetric distribution of radicals and ion density in the plasma during the process, that is, the plasma distribution becomes non-uniform. As a result, the etching of the wafer becomes non-uniform, affecting the etching quality or efficiency.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to solve at least one of the technical problems existing in the prior art, the present invention compensates for the difference in the radial current distribution of the coil, improves the radial and angular distribution uniformity of the coupling energy generated below the coil, thereby not only improving the radial distribution uniformity of radicals and ion density in the plasma, but also improving the overall withstand voltage ability of the coil, and thus a coil structure for plasma generation of a semiconductor process device and a semiconductor process device that can also achieve a large power supply are proposed.

Means for Solving the Problems

[0006] To achieve the above object, the present invention includes at least one coil unit, each of the coil units includes M coil groups, M is an integer of 4 or more, the M coil groups have the same structure and are connected in parallel to each other. Each of the coil groups includes N layers of planar coils parallel to each other, N is an even number of 4 or more. The planar coils of each layer of the M coil groups correspond to each other one-to-one and are provided on the same layer. The M planar coils located on the same layer are evenly distributed at intervals in the circumferential direction of the planar coil. The N layers of planar coils of each coil group are provided at intervals along the direction perpendicular to the plane where the planar coil is located and are connected in series end-to-end in order. The orthographic projections of the planar coils of two adjacent layers on the plane where the planar coils are located are mirror-symmetric, and a coil structure for plasma generation of a semiconductor processing apparatus is provided.

[0007] Optionally, M is an even number of 4 or more. The input ends of the M coil groups are provided on the same layer and are divided into M / 2 input end groups in the circumferential direction of the planar coil. Each input end group includes the input ends of two adjacent coil groups. A first extension segment for electrically connecting the two is connected between the input ends of two adjacent coil groups. The first extension segments of the M / 2 input end groups are electrically connected to each other. The output ends of the M coil groups are provided on the same layer and are divided into M / 2 output end groups in the circumferential direction of the planar coil. Each output end group includes the output ends of two adjacent coil groups. A second extension segment for electrically connecting the two is connected between the output ends of two adjacent coil groups. The second extension segments of the M / 2 output end groups are electrically connected to each other.

[0008] Optionally, the extending direction of the first extension segment is the same as the extending direction of the planar coil connected to the first extension segment of one of the coil groups, and the extending direction of the second extension segment is the same as the extending direction of the planar coil connected to the second extension segment of one of the coil groups.

[0009] Optionally, at an intermediate position of the first extension segment, a first wiring terminal for electrically connecting to an output end of an RF power supply is provided, and at an intermediate position of the second extension segment, a second wiring terminal for electrically connecting to an input end of the RF power supply is provided.

[0010] Optionally, M / 2 of the first wiring terminals are divided into M / 4 first terminal groups in the circumferential direction of the planar coil. Each of the first terminal groups includes two adjacent first wiring terminals. Between two adjacent first wiring terminals, a first connection bar for electrically connecting them is connected. At an intermediate position of the first connection bar, an input wiring terminal for electrically connecting to an output end of an RF power supply is provided. M / 2 of the second wiring terminals are divided into M / 4 second terminal groups in the circumferential direction of the planar coil. Each of the second terminal groups includes two adjacent second wiring terminals. Between two adjacent second wiring terminals, a second connection bar for electrically connecting them is connected. At an intermediate position of the second connection bar, an output wiring terminal for electrically connecting to an input end of an RF power supply is provided.

[0011] Optionally, M / 4 of the first connection bars are evenly distributed in the circumferential direction of the planar coil, M / 4 of the second connection bars are evenly distributed in the circumferential direction of the planar coil. The diameter of the circle where M / 4 of the first connection bars are located is the same as the diameter of the circle where M / 4 of the second connection bars are located. M / 4 of the first connection bars and M / 4 of the second connection bars are offset from each other in the circumferential direction of the planar coil.

[0012] Optionally, N is equal to 4, and the number of turns of the planar coil in each layer is 0.25 turn.

[0013] Optionally, there are a plurality of the coil units, and the coil groups of the plurality of coil units have different dimensions and are provided in a nested manner with each other.

[0014] Optionally, there are two coil units, namely a first coil unit and a second coil unit respectively. The outer diameter of the second coil unit is smaller than the inner diameter of the first coil unit. The number of layers of the planar coils in the coil group of the first coil unit and the number of layers of the planar coils in the coil group of the second coil unit are set based on the magnitude of the power supplied respectively.

[0015] As another technical solution, the present invention includes a first coil structure and a second coil structure nested with each other. The first coil structure adopts the coil structure for plasma generation of the above-mentioned semiconductor process apparatus according to the present invention. The second coil structure includes two layers of planar coils connected in series end-to-end in parallel with each other. The orthographic projection on the plane where the planar coils of the two layers of planar coils are located is a mirror-symmetric coil structure.

[0016] Optionally, the distance between each adjacent two layers of the planar coils is 10 mm or less.

[0017] Optionally, the number of the coil groups is 4 or more and 64 or less.

[0018] Optionally, the height of the planar coils in the direction perpendicular to the plane where the planar coils are located is 2 mm or more and 15 mm or less.

[0019] As another technical solution, the present invention includes an RF source, a reaction chamber, and the coil structure for plasma generation of the above-mentioned semiconductor process apparatus according to the present invention. A dielectric window is provided at the top of the reaction chamber. The coil structure is provided above the dielectric window. The RF source is used to supply RF power to the coil structure, and a semiconductor process apparatus is further provided.

Advantages of the Invention

[0020] The coil structure for plasma generation in the semiconductor process apparatus according to the present invention includes M coil groups, where M is an integer of 4 or more. The M coil groups have the same shape, are connected in parallel to each other, and each coil group includes N layers of planar coils parallel to each other, where N is an even number of 4 or more. The planar coils of each layer of the M coil groups are provided in the same layer in a one-to-one correspondence. The M planar coils located in the same layer are evenly distributed at intervals in the circumferential direction of the planar coil, so that the M coil groups have angular symmetry in the circumferential direction of the planar coil, that is, they are symmetric with respect to the circumferential direction of the planar coil. Thereby, it is possible to avoid the occurrence of a difference in current distribution in the circumferential direction, further improve the uniformity of the angular distribution of the plasma density, and improve the uniformity of the process.

[0021] And the N layers of planar coils of each coil group are provided at intervals along the direction perpendicular to the plane where the planar coil is located, and are connected in series end-to-end in sequence. The orthographic projection of the planar coils of two adjacent layers on the plane where the planar coil is located is mirror-symmetric. By making two adjacent layers of planar coils mirror-symmetric, the magnetic field and electric field generated by the planar coil of one layer and the planar coil of the other adjacent layer can be compensated for each other. Thereby, the difference in current distribution in the radial direction of the coil can be compensated, and the uniformity of the radial distribution of the coupling energy generated below the coil can be improved. Thereby, the uniformity of the radial distribution of radicals and ion density in the plasma can be improved, and the uniformity of the process can be improved.

[0022] Also, by providing the even number of planar coils of 4 or more layers of each coil group at intervals along the direction perpendicular to the plane where the planar coil is located, the interval between the input end and the output end of the coil group (that is, the interval between the topmost planar coil and the lowermost planar coil) can be increased. Also, since the total voltage applied by the RF power supply to the input end and the output end of the coil group is constant, the voltage received by each layer of planar coil becomes 1 / N of the total voltage. That is, the overall breakdown voltage capacity of the coil group can be improved, and a large power supply can be realized while meeting the requirements of process uniformity.

[0023] The present invention further provides a coil structure. By using the coil structure according to the present invention in combination with two layers of planar coils parallel to each other, it can be applied when the magnitudes of the supply powers of the inner ring and the outer ring are different. That is, the coil structure according to the present invention can be applied to large power supply (greater than 5 kW), and the two layers of planar coils connected in series parallel to each other can be applied to small power supply (2 kW or less), thereby meeting various different process requirements.

[0024] By adopting the coil structure according to the present invention, the semiconductor process apparatus according to the present invention compensates for the difference in the current distribution in the radial direction of the coil, improves the radial distribution uniformity of the coupling energy generated below the coil, thereby not only improving the radial and angular distribution uniformities of the radicals and ion densities in the plasma, but also improving the overall withstand voltage ability of the coil, and thereby realizing large power supply.

Brief Description of the Drawings

[0025]

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Mode for Carrying Out the Invention

[0026] In order for those skilled in the art to better understand the technical solution of the present invention, the coil structure for plasma generation and the semiconductor process apparatus according to the present invention will be described in detail below with reference to the drawings.

[0027] This embodiment provides a coil structure for plasma generation of a semiconductor process apparatus. The semiconductor process apparatus can be used to perform an etching process on a wafer. The coil structure is used to excite a process gas in a reaction chamber as an upper electrode to form plasma.

[0028] The coil structure includes M coil groups, where M is an integer of 4 or more. Each coil group includes N layers of planar coils that are parallel to each other, where N is an even number of 4 or more. The N layers of planar coils are provided at intervals along a direction perpendicular to the plane in which the planar coils are located, and are connected in series end-to-end in sequence. The orthographic projections of the planar coils of each adjacent two layers in the plane in which the planar coils are located are mirror-symmetric. Mirror image means that, among two adjacent layers of planar coils, the shape of the orthographic projection of the planar coils of one layer in the plane in which the planar coils are located (hereinafter abbreviated as the first projection A) is the same as the shape of the orthographic projection of the planar coils of the other layer in the plane in which the planar coils are located (hereinafter abbreviated as the second projection B), but the spiral directions are opposite. Specifically, both the first projection A and the second projection B have front and back surfaces parallel to the plane in which the planar coils are located, but the shape of one surface of the first projection A and the second projection B is the same as the shape of the other back surface of the first projection A and the second projection B. Symmetry means that all parameters of the shape of one surface of the first projection A and the second projection B and the shape of the other back surface of the first projection A and the second projection B are exactly the same.

[0029] By making the adjacent two layers of planar coils of each coil group mirror-symmetric, the magnetic fields and electric fields generated by the planar coil of one layer and the planar coil of the other layer adjacent thereto can be compensated for each other, thereby compensating for the difference in the radial current distribution of the coils and improving the radial distribution uniformity of the coupling energy generated below the coils. As a result, the radial distribution uniformity of radicals and ion density in the plasma can be improved, and the uniformity of the process can be improved.

[0030] As a comparative example of one embodiment of the present invention, as shown in FIG. 3A, the coil structure 03 is electrically connected to the RF power supply 1 via the matcher 2, and the RF power supply 1 is used to apply RF power to the coil structure 03. The coil structure 03 includes a first coil unit 03a located on the outer ring and a second coil unit 03b located on the inner ring. Both have the same structure, differ only in dimensions, and are nested with each other. Taking the structure of the first coil unit 03a as an example, the first coil unit 03a includes a first planar coil 031 and a second planar coil 032. Both are provided at intervals in the vertical direction and are connected in series with each other. The orthographic projection in the plane where the planar coils of the first planar coil 031 and the second planar coil 032 are located is mirror-symmetric. In this way, the difference in the radial current distribution of the coils can be compensated, and the radial distribution uniformity of the coupling energy generated below the coils can be improved. However, in order to avoid the compensation effect of the difference in the current distribution between the first planar coil 031 and the second planar coil 032 from becoming ineffective, the vertical interval D1 between the first planar coil 031 and the second planar coil 032 should not be too large (for example, when it is 10 mm or less, the process uniformity is 1% or less). As a result, the withstand voltage capacity of the coil structure 03 becomes low (4 kV or less), and thus the maximum allowable supply power of the coil structure 03 becomes 2 KW, making it inapplicable to processes that supply large power (greater than 5 KW).

[0031] As shown in FIG. 3B, another coil structure 03' increases the vertical interval between the first planar coil 031 and the second planar coil 032 to D2 compared with the coil structure 03. The vertical interval D2 is, for example, 30 mm. By increasing this vertical interval, the withstand voltage capacity of the coil structure 03' can be improved to 12 kV or more, and it can be applied to the process of supplying large power (greater than 5 kW). However, because the vertical interval is too large, the compensation effect of the difference in current distribution between the first planar coil 031 and the second planar coil 032 becomes invalid, and the uniformity of the process deteriorates from 1% to 2.7%, and the uniformity requirement (1.5% or less) of the process cannot be satisfied.

[0032] To solve the above problems, as shown in FIG. 4A, the coil structure 3 according to the embodiment of the present invention includes at least one coil unit. Each coil unit includes M coil groups, where M is an integer greater than or equal to 4. When there are multiple coil units, the coil groups of the multiple coil units have different dimensions and are provided nested with each other. For example, FIG. 4A shows two coil units, namely a first coil unit 3a and a second coil unit 3b that are nested with each other. The outer diameter of the second coil unit 3b is smaller than the inner diameter of the first coil unit 3a. Of course, the embodiments of the present invention are not limited to this. In actual applications, according to specific needs, there may be only one coil unit, or three or more coil units.

[0033] The first coil unit 3a and the second coil unit 3b have the same structure and differ only in dimensions. Taking the first coil unit 3a as an example, it includes M coil groups, and each coil group includes N layers of planar coils parallel to each other. N is an even number of 4 or more. Taking N = 4 as an example, the four-layer planar coils are, in order from top to bottom, the first planar coil 31, the second planar coil 32, the third planar coil 33, and the fourth planar coil 34. The N-layer planar coils are provided at intervals along the direction perpendicular to the plane in which the planar coils are located (i.e., the vertical direction in FIG. 4A), and are connected in series end-to-end in order, that is, the mutual series connection of the N-layer planar coils is realized, and the orthographic projection of the planar coils of each adjacent two layers on the plane in which the planar coils are located is mirror-symmetric. Note that FIG. 4A only schematically shows the planar coils as "mouths" and does not represent the specific structure of the planar coils.

[0034] The coil group includes N layers of planar coils parallel to each other, where N is an even number of 4 or more. That is, the coil group has an even number of planar coils of 4 layers or more. As a result, compared with the coil structure 03 shown in FIG. 3A above, the interval between the first planar coil 31 in the uppermost layer and the fourth planar coil 34 in the lowermost layer, which is the vertical interval D5 between the input end and the output end of the coil group, can be increased. The interval D5 is, for example, 30 mm or more. In this way, the withstand voltage capacity between the first planar coil 31 in the uppermost layer and the fourth planar coil 34 in the lowermost layer can be improved to 12 KV or more, and it can be applied to the process of supplying large power (greater than 5 KW). Also, a second planar coil 32 adjacent thereto is provided below the first planar coil 31 in the uppermost layer. The orthographic projection of the second planar coil 32 and the planar coil of the first planar coil 31 on the plane where the planar coils are located is mirror-symmetrical. That is, the shapes are the same, but the spiral directions are opposite. In this way, the magnetic fields and electric fields generated by both can compensate each other. That is, the distribution of the total magnetic field and the total electric field formed by overlapping the magnetic field and the electric field generated by the second planar coil 32 with the magnetic field and the electric field generated by the first planar coil 31 respectively is mirror-symmetrical. Thereby, the difference in the radial current distribution of the planar coils in each layer can be compensated. Similarly, a third planar coil 33 adjacent thereto is provided above the fourth planar coil 34 in the lowermost layer. The orthographic projection of the third planar coil 33 and the planar coil of the fourth planar coil 34 on the plane where the planar coils are located is mirror-symmetrical, so that the magnetic fields and electric fields generated by both can compensate each other. Also, the orthographic projection of the second planar coil 32 and the third planar coil 33 on the plane where the planar coils are located is mirror-symmetrical, so that the magnetic fields and electric fields generated by both can compensate each other. Thereby, the difference in the radial current distribution of the planar coils in each layer is compensated, and the radial distribution uniformity of the coupling energy generated below the coil can be improved. Thereby, the radial distribution uniformity of the radicals and ion density in the plasma is improved, and the uniformity of the process is improved.

[0035] Based on this, even numbers of planar coils with four or more layers are provided at intervals along a direction perpendicular to the plane in which the planar coils are located. Compared with the coil structure 03 in FIG. 3A, the distance (i.e., the distance between the topmost planar coil and the bottommost planar coil) D5 between the input end and the output end of the coil group can be increased. The distance D5 can be increased to, for example, 30 mm or more. Also, the distance between the first planar coil 31 in the topmost layer and the second planar coil 32 adjacent to it, and the distance between the fourth planar coil 34 in the bottommost layer and the third planar coil 33 adjacent to it are both D3, and the distance between the adjacent second planar coil 32 and third planar coil 33 is D4. Both the distances D3 and D4 are, for example, 10 mm or less. In this way, it can be ensured that the mutual compensation effect of the difference in current distribution between every two adjacent layers of planar coils is not invalidated, thereby ensuring that the requirements for process uniformity are met. Also, since the total voltage applied by the RF power supply 1 to the input end and the output end of the coil group via the matcher 2 is constant, the voltage received by each layer of planar coil is only 1 / N of the total voltage, thereby improving the overall breakdown voltage capability of the coil group and realizing large-power supply while meeting the requirements for process uniformity.

[0036] In actual applications, the number of layers of the planar coils can be set according to specific requirements. That is, regarding the value of N, the greater the supplied power and the greater the distance (i.e., the distance between the topmost planar coil and the bottommost planar coil) between the input end and the output end of the coil group, the greater the value of N is required to be.

[0037] Furthermore, regarding the distance between every two adjacent layers of planar coils, it is not preferable for it to be too large in order to ensure that the mutual compensation effect of the difference in current distribution between every two adjacent layers of planar coils is not invalidated. On the other hand, it is also not preferable for it to be too small to avoid the occurrence of ignition phenomena due to the distance between every two adjacent layers of planar coils being too close. Optionally, the distance between every two adjacent layers of planar coils is 10 mm or less, for example, 5 mm, 7 mm, etc.

[0038] In some selectable embodiments, the shape of the planar coil of each layer is a spiral involute.

[0039] In some selectable embodiments, the height of the planar coil of each layer in the direction perpendicular to the plane where the planar coil is located is 2 mm or more and 15 mm or less.

[0040] In some selectable embodiments, the number of turns of the planar coil of each layer can be set according to the required inductance amount. The larger the required inductance amount, the more turns. Specifically, the inductance amount is proportional to the square of the number of turns. The number of turns of the planar coils of different layers is the same. Also, it is not preferable that the number of turns of the planar coil of each layer is too large. If it is too large, the space occupied in the circumferential direction is large, so the number of coil groups (that is, the value of M) is limited. Preferably, N = 4, and the number of turns of the planar coil of each layer is 0.25 turns. In this way, the total number of turns of the four-layer planar coil is 1 turn, that is, it makes one full turn in the circumferential direction.

[0041] In one specific embodiment, as shown in reference to FIG. 4B, taking the first coil unit 3a as an example, N = 4, and the number of turns of the planar coil in each layer is 2 turns. The four-layer planar coil is, in order from top to bottom, the first planar coil 31, the second planar coil 32, the third planar coil 33, and the fourth planar coil 34. The four-layer planar coil is provided at intervals along the direction perpendicular to the plane in which the planar coil is located, and is connected in series end-to-end in order. Specifically, every two adjacent layers of planar coils are connected in series via the connection post 4 and are electrically conductive. The connection post 4 is provided, for example, along the direction perpendicular to the plane in which the planar coil is located. The input end 31a and the output end 31b of the coil group are respectively one end of the outer ring of the first planar coil 31 in the uppermost layer and the fourth planar coil 34 in the lowermost layer. Each of the four-layer planar coils is a spiral involute, with the same parameters, and the spiral directions of two adjacent layers of planar coils are opposite. Specifically, in the direction perpendicular to the plane in which the planar coil is located, in a top view, the spiral direction of the first planar coil 31 is clockwise, and the spiral direction of the adjacent second planar coil 32 is counterclockwise. The two are mirror-symmetric. The spiral direction of the third planar coil 33 adjacent to the second planar coil 32 is clockwise, that is, the third planar coil 33 is mirror-symmetric with the second planar coil 32 and overlaps with the first planar coil 31. The spiral direction of the fourth planar coil 34 adjacent to the third planar coil 33 is counterclockwise, that is, the fourth planar coil 34 is mirror-symmetric with the third planar coil 33 and overlaps with the second planar coil 32.

[0042] In another specific embodiment, as shown in conjunction with FIGS. 5 to 8, taking the first coil unit 3a as an example, N = 4, and the number of turns of the planar coil in each layer is 0.25 turn. The four-layer planar coil is, in order from top to bottom, the first planar coil 31, the second planar coil 32, the third planar coil 33, and the fourth planar coil 34. The four-layer planar coil is provided at intervals along the direction perpendicular to the plane where the planar coil is located (i.e., the Z direction in FIG. 7), and is connected in series end-to-end in order. Specifically, every two adjacent layers of planar coils are connected in series via the connection post 4 and are electrically conductive. The connection post 4 is provided, for example, along the direction perpendicular to the plane where the planar coil is located. The input end 31a and the output end 31b of the coil group are respectively the two ends close to each other of the first planar coil 31 in the uppermost layer and the fourth planar coil 34 in the lowermost layer. Each of the four-layer planar coils is a spiral involute, with the same parameters, and the spiral directions of every two adjacent layers of planar coils are opposite. Specifically, as shown in FIG. 6, the first planar coil 31 and the second planar coil 32 are symmetric with respect to the second axis O2 parallel to the plane where the planar coil is located (the spiral directions are opposite), the second planar coil 32 and the third planar coil 33 are symmetric with respect to the first axis O1 parallel to the plane where the planar coil is located (the spiral directions are opposite), and the third planar coil 33 and the fourth planar coil 34 are symmetric with respect to the second axis O2 parallel to the plane where the planar coil is located (the spiral directions are opposite).

[0043] As shown in FIG. 8, the vertical interval D5 between the input end 31a and the output end 31b of the coil group is equal to the sum of twice the interval D3, the interval D4, the height H1 of the second planar coil 32, and the height H2 of the third planar coil 33, that is, D5 = 2×D3 + D4 + H1 + H2. Taking the example that both the interval D3 and the interval D4 are equal to 7 mm, and both the height H1 and the height H2 are equal to 5 mm, the interval D5 is 31 mm, which can meet the process requirements for the withstand voltage ability of the coil structure.

[0044] In the case of the coil structure shown in FIG. 1, the shape of the orthographic projection in its radial cross-section has circumferential (i.e., angular) asymmetry. Specifically, as shown in FIG. 2B, the radial cross-section is divided into four quadrant regions (I, II, III, IV). In the process where the involute of each planar coil extends from the inner end to the outer end, its radius gradually increases. Therefore, the portions in the first quadrant region I and the third quadrant region III of the coil structure are significantly different from the portions in the second quadrant region II and the fourth quadrant region IV. As a result, a difference in current distribution occurs in the circumferential (i.e., angular) direction of the coil structure, and furthermore, the distribution of the electromagnetic field becomes non-uniform, causing an asymmetric distribution of radicals and ion density in the plasma during the process treatment, and further making the angular distribution of the plasma density non-uniform, ultimately affecting the uniformity of the process.

[0045] To solve the above technical problems, M coil groups are designed, where M is an integer of 4 or more. The M coil groups have the same structure and are connected in parallel to each other. The planar coils of each layer of the M coil groups correspond to each other one-to-one and are provided on the same layer. The M planar coils located on the same layer are evenly distributed at intervals in the circumferential direction of the planar coil. That is, the M planar coils located on the same layer are arranged at different rotation angles in the circumferential direction. Specifically, taking M = 4 as an example, as shown in FIGS. 9B to 12, the four coil groups are the first coil group 3a1, the second coil group 3a2, the third coil group 3a3, and the fourth coil group 3a4, respectively. Each of the four coil groups includes N layers of planar coils (for example, N = 4) parallel to each other. Taking the four-layer planar coil shown in FIG. 5 as an example, in the M coil groups, the M first planar coils 31 are provided on the same layer and are evenly distributed at intervals in the circumferential direction of the planar coil. The M second planar coils 32 are provided on the same layer and are evenly distributed at intervals in the circumferential direction of the planar coil. The M third planar coils 33 are provided on the same layer and are evenly distributed at intervals in the circumferential direction of the planar coil. The M fourth planar coils 34 are provided on the same layer and are evenly distributed at intervals in the circumferential direction of the planar coil. In other words, when any one of the coil groups rotates by a predetermined angle clockwise or counterclockwise in the circumferential direction of the planar coil, it overlaps with another adjacent coil group. For example, FIG. 9B shows four coil groups. In this case, taking the first coil group 3a1 as an example, when it rotates 90° clockwise or counterclockwise in the circumferential direction of the planar coil, it overlaps with another adjacent coil group (for example, the second coil group 3a2 or the fourth coil group 3a4). In the M coil groups, since the M planar coils provided on the same layer are distributed on the same circumference, it can be easily understood that the first ends and the second ends of the M planar coils are on two concentric circumferences, respectively.

[0046] The M coil groups have the same shape and can be evenly distributed in the circumferential direction of the planar coil. Therefore, the M planar coils corresponding to each layer of the M coil groups jointly form a single approximate circle in the circumferential direction of the planar coil. As a result, the M coil groups have angular symmetry in the circumferential direction of the planar coil, that is, they are symmetric with respect to the circumferential direction of the planar coil. Thereby, it is possible to avoid the occurrence of differences in the current distribution in the circumferential direction, and further improve the uniformity of the angular distribution of the plasma density and the uniformity of the process.

[0047] In addition, when the number of coil groups is less than 4, for example, (a) of FIG. 9A shows one coil group, and the coil group has a two-layer planar coil structure. (b) of FIG. 9A shows two coil groups, and each coil group has a two-layer planar coil structure. As can be seen from (a), each layer of the coil group has only one planar coil, and the coil structure is asymmetric in the circumferential direction (i.e., the angular direction) of the planar coil, and there is still a difference in the current distribution. As can be seen from (b), each layer of each coil group has two planar coils, and although the number of planar coils increases, since the two planar coils in the same layer are mirror symmetric, the coil structure shown in (b) is still asymmetric in the circumferential direction (i.e., the angular direction) of the planar coil. The inventor has found that only when there are 4 or more (i.e., M≥4) coil groups and the M planar coils located in the same layer are arranged at different rotation angles in the circumferential direction, it is possible to form a single approximate circle, thereby meeting the process requirements for angular uniformity. Also, the larger the number of the above coil groups, that is, the larger the value of M, the higher the angular uniformity. Preferably, it is found that M = 4 or 8 or 16.

[0048] In some other selectable embodiments, as can be seen with reference to FIGS. 13 and 14, M = 16, and the 16 coil groups are the first coil group 3a1 to the sixteenth coil group 3a16 respectively. Note that the larger the number of coil groups, that is, the larger the value of M, the better the angular symmetry of the coil structure composed of M coil groups, which is advantageous for improving the symmetry of the angular distribution of the plasma density. In some preferred embodiments, the number of coil groups (that is, the value of M) is 2 or more and 64 or less.

[0049] In some selectable embodiments, the form in which the M coil groups are connected in parallel to each other may specifically be that the input end and the output end of each coil group (that is, the two ends close to each other of the topmost planar coil and the bottommost planar coil) are electrically connected to the input end and the output end of the RF power source 1 via the matching device 2 respectively. Optionally, in order to reduce the number of wiring terminals of the RF power source 1, M is an even number of 2 or more. The input ends of the M coil groups are provided on the same layer (both are located on the topmost layer or the bottommost layer), and are divided into M / 2 input end groups (in pairs of two) in the circumferential direction of the planar coil. Each input end group includes the input ends of two adjacent coil groups, and a first extension segment for electrically connecting the two is connected between the input ends of the two adjacent coil groups. The first extension segments of the M / 2 input end groups are electrically connected to each other. Similarly, the output ends of the M coil groups are provided on the same layer (both are located on the bottommost layer or the topmost layer), and are divided into M / 2 output end groups (in pairs of two) in the circumferential direction of the planar coil. Each output end group includes the output ends of two adjacent coil groups, and a second extension segment for electrically connecting the two is connected between the output ends of the two adjacent coil groups. The second extension segments of the M / 2 output end groups are electrically connected to each other.

[0050] Taking M = 16 as an example, the input ends of the 16 coil groups are provided on the same layer and are divided into 8 input end groups in the circumferential direction of the planar coil. Each input end group includes the input ends of two adjacent coil groups. FIGS. 15 and 16 show the input ends 31a of two adjacent coil groups (3a1, 3a2) among the 16 coil groups. A first extension segment 5a for electrically connecting the two is connected between the input ends 31a of the two adjacent coil groups (3a1, 3a2), and the first extension segment 5a is electrically connected to another adjacent first extension segment 5a adjacent thereto. Similarly, FIGS. 15 and 16 show the output ends 31b of two adjacent coil groups (3a1, 3a2) among the 16 coil groups. A second extension segment 5b for electrically connecting the two is connected between the output ends 31b of the two adjacent coil groups (3a1, 3a2), and the second extension segment 5b is electrically connected to another adjacent second extension segment 5b adjacent thereto. Thereby, it is possible to realize that the 16 coil groups are connected in parallel with each other.

[0051] In some selectable embodiments, as shown in FIG. 15, the extending direction of the first extension segment 5a coincides with the extending direction of the planar coil connected to the first extension segment 5a of one coil group. For example, in FIG. 15, the first extension segment 5a coincides with the extending direction of the planar coil (for example, the uppermost planar coil) connected to it in the first coil group 3a1. The extending direction of the second extension segment 5b coincides with the extending direction of the planar coil connected to the second extension segment 5b of one coil group. For example, in FIG. 15, the second extension segment 5b coincides with the extending direction of the planar coil (for example, the lowermost planar coil) connected to it in the second coil group 3a2.

[0052] In some selectable embodiments, as shown in FIG. 15, at an intermediate position of the first extension segment 5a, a first wiring terminal 51a for electrically connecting to the output end of the RF power supply 1 is provided, and at an intermediate position of the second extension segment 5b, a second wiring terminal 51b for electrically connecting to the input end of the RF power supply 1 is provided. In this way, it is possible to ensure that the total lengths of two adjacent coil groups are the same, thereby making the paths through which current flows through the two coil groups the same.

[0053] It should be noted that the form in which the M coil groups are connected in parallel to each other may adopt any other form. For example, the input ends of the M coil groups are directly electrically connected, and the output ends of the M coil groups are directly electrically connected.

[0054] In some selectable embodiments, in order to further reduce the number of wiring terminals of the RF power supply 1, M / 2 first wiring terminals 51a are divided into M / 4 first terminal groups (in pairs of two) in the circumferential direction of the planar coil. As shown in FIG. 17, each first terminal group includes two adjacent first wiring terminals 51a. Between two adjacent first wiring terminals 51a, a first connection bar 6a for electrically connecting the two is connected. At an intermediate position of the first connection bar 6a, an input wiring terminal 61a for electrically connecting to the output end of the RF power supply 1 is provided. Similarly, M / 2 second wiring terminals 51b are divided into M / 4 second terminal groups (in pairs of two) in the circumferential direction of the planar coil. Each second terminal group includes two adjacent second wiring terminals 51b. Between two adjacent second wiring terminals 51b, a second connection bar 6b for electrically connecting the two is connected. At an intermediate position of the second connection bar 6b, an output wiring terminal 61b for electrically connecting to the input end of the RF power supply 1 is provided. Taking M = 16 as an example, eight first wiring terminals 51a are divided into four first terminal groups in the circumferential direction of the planar coil, and eight second wiring terminals 51b are divided into four second terminal groups in the circumferential direction of the planar coil.

[0055] In some selectable embodiments, to ensure the circumferential symmetry of the coil structure, as shown in FIG. 17, M / 4 first connection bars 6a are evenly distributed in the circumferential direction of the planar coil, M / 4 second connection bars 6b are evenly distributed in the circumferential direction of the planar coil, the diameter of the circle where the M / 4 first connection bars 6a are located is the same as the diameter of the circle where the M / 4 second connection bars 6b are located, and the M / 4 first connection bars 6a and the M / 4 second connection bars 6b are offset from each other in the circumferential direction of the planar coil, that is, they are provided in a staggered manner in the circumferential direction of the planar coil. The fact that the M / 4 first connection bars 6a and the M / 4 second connection bars 6b are offset from each other in the circumferential direction of the planar coil enables the wiring connection layout between the RF power source and the connection bars to be designed more easily. Of course, the embodiments of the present invention are not limited thereto. For example, as shown in FIG. 18, the M / 4 first connection bars 6a and the M / 4 second connection bars 6b may correspond one-to-one and overlap each other in the direction perpendicular to the plane where the planar coil is located.

[0056] In some selectable embodiments, the coil structure 3 includes a plurality of coil units, and the coil groups of the plurality of coil units have different dimensions and are provided nested with each other. For example, FIG. 19 shows two coil units, namely the first coil unit 3a and the second coil unit 3b respectively. The outer diameter of the second coil unit 3b is smaller than the inner diameter of the first coil unit 3a, and the two are nested with each other.

[0057] Optionally, the number of layers of the planar coils in the coil group of the first coil unit 3a is the same as the number of layers of the planar coils in the coil group of the second coil unit 3b. For example, both are 4 layers. However, the embodiments of the present invention are not limited thereto. Depending on the power ratio between the first coil unit 3a and the second coil unit 3b, the number of layers of the planar coils in the coil group of the first coil unit 3a and the number of layers of the planar coils in the coil group of the second coil unit 3b may be different. Specifically, the greater the supplied power, the more the number of layers, while the smaller the supplied power, the fewer the number of layers.

[0058] As another technical solution, this embodiment further provides a coil structure, which includes a first coil structure and a second coil structure nested with each other. Specifically, as shown in FIG. 20, both the first coil structure 201 and the second coil structure 201 are annular, with different dimensions. The first coil structure 201 is located on the outer ring, and the second coil structure 202 is located on the inner ring, or, as shown in FIG. 21, the second coil structure 202 is located on the outer ring, and the first coil structure 201 is located on the inner ring.

[0059] The first coil structure 201 adopts the above-mentioned coil structure according to this embodiment. The first coil structure 201 has one coil unit, and the coil unit includes M coil groups, where M is an integer greater than or equal to 4. Each coil group includes N layers of planar coils parallel to each other, where N is an even number greater than or equal to 4. The orthographic projection of the planar coils of each adjacent two layers of planar coils on the plane where they are located is mirror-symmetric. Four layers of planar coils are schematically shown in FIGS. 20 and 21. The coil group includes N layers of planar coils parallel to each other, where N is an even number greater than or equal to 4, that is, the coil group has an even number of planar coils of 4 layers or more. In this way, the withstand voltage capacity between the top layer planar coil and the bottom layer planar coil can be improved to 12 KV or more, and it can be applied to the process of supplying large power (greater than 5 KW) to the inner ring or the outer ring.

[0060] The second coil structure 202 includes two layers of planar coils connected in series end-to-end in parallel with each other. The orthographic projection of the planar coils of the two layers of planar coils on the plane where they are located is mirror-symmetric. The two layers of planar coils in the second coil structure 202 adopt, for example, the first planar coil 031 and the second planar coil 032 shown in FIG. 3A. The second coil structure 202 can be applied when the supply power of the outer ring or the inner ring is small (2 kW or less).

[0061] The coil structure according to the embodiment of the present invention can be used in combination with the above coil structure according to the embodiment of the present invention, which is a two-layer planar coil connected in series end-to-end in parallel with each other, and can be applied to situations where the magnitudes of the supply powers of the inner ring and the outer ring are different. That is, the first coil structure 201 can be applied to a large power supply (greater than 5 kW), and the second coil structure 202 can be applied to a small power supply (2 kW or less), thereby satisfying various different process requirements.

[0062] As another technical solution, this embodiment further provides a semiconductor process apparatus. For example, as shown in FIG. 22, the semiconductor process apparatus includes an RF power source 1 for an upper electrode, a matcher 2, a reaction chamber 100, and a coil structure 3. A dielectric window 101 is provided at the top of the reaction chamber 100, and the coil structure 3 is provided above the dielectric window 101. The coil structure 3 adopts the coil structure according to each of the above embodiments of the present invention. For example, the coil structure 3 shown in FIG. 4A is adopted.

[0063] The RF power source 1 is used to supply RF power to the coil structure 3 through the matcher 2 to excite the process gas in the reaction chamber 100 to form plasma. In addition, a base 102 for placing a wafer is provided in the reaction chamber 100, and the base 102 is electrically connected to an RF source 103 for a lower electrode. The RF source 103 is used to apply an RF bias to the base 102 to attract the plasma and move it to the surface of the wafer.

[0064] By adopting the coil structure according to the present invention, the semiconductor process apparatus according to the present invention can compensate for the difference in the current distribution in the radial direction of the coil, improve the radial distribution uniformity of the coupling energy generated below the coil, thereby not only improving the radial distribution uniformity of the radicals and ion density in the plasma, but also improving the overall breakdown voltage capability of the coil, and thereby realizing a large power supply.

[0065] The above embodiments are merely exemplary embodiments for explaining the principles of the present invention, and it should be understood that the present invention is not limited thereto. Those skilled in the art can make various modifications and improvements without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the protection scope of the present invention.

Claims

1. A coil structure for plasma generation in a semiconductor processing apparatus, wherein the coil structure includes at least one coil unit, each of the coil units includes M coil groups, M is an integer of 4 or more, the M coil groups have the same structure and are connected in parallel to each other, each of the coil groups includes N-layer planar coils parallel to each other, N is an even number of 4 or more, the planar coils of each layer of the M coil groups correspond to each other one-to-one and are provided on the same layer, and the M planar coils located on the same layer are evenly distributed at intervals in the circumferential direction of the planar coils, the N-layer planar coils of each of the coil groups are provided at intervals along a direction perpendicular to the plane in which the planar coils are located, and are connected in series end-to-end in sequence, and the orthographic projections of the planar coils of each adjacent two layers on the plane in which the planar coils are located are mirror-symmetric. A coil structure for plasma generation in a semiconductor processing apparatus, characterized in that.

2. wherein M is an even number of 4 or more, the input ends of the M coil groups are provided on the same layer and are divided into M / 2 input end groups in the circumferential direction of the planar coils, each of the input end groups includes the input ends of two adjacent coil groups, and a first extension segment for electrically connecting the two is connected between the input ends of the two adjacent coil groups, and the first extension segments of the M / 2 input end groups are electrically connected to each other, the output ends of the M coil groups are provided on the same layer and are divided into M / 2 output end groups in the circumferential direction of the planar coils, each of the output end groups includes the output ends of two adjacent coil groups, and a second extension segment for electrically connecting the two is connected between the output ends of the two adjacent coil groups, and the second extension segments of the M / 2 output end groups are electrically connected to each other. The coil structure according to claim 1, characterized in that.

3. the extending direction of the first extension segment is the same as the extending direction of the planar coil connected to the first extension segment of one of the coil groups, the extending direction of the second extension segment is the same as the extending direction of the planar coil connected to the second extension segment of one of the coil groups. The coil structure according to claim 2, characterized in that.

4. At an intermediate position of the first extension segment, a first wiring terminal for electrically connecting to an output terminal of an RF power supply is provided, and at an intermediate position of the second extension segment, a second wiring terminal for electrically connecting to an input terminal of the RF power supply is provided. The coil structure according to claim 2, characterized in that.

5. The M / 2 first wiring terminals are divided into M / 4 first terminal groups in the circumferential direction of the planar coil. Each of the first terminal groups includes two adjacent first wiring terminals. Between the two adjacent first wiring terminals, a first connection bar for electrically connecting them is connected. At an intermediate position of the first connection bar, an input wiring terminal for electrically connecting to an output terminal of an RF power supply is provided. The M / 2 second wiring terminals are divided into M / 4 second terminal groups in the circumferential direction of the planar coil. Each of the second terminal groups includes two adjacent second wiring terminals. Between the two adjacent second wiring terminals, a second connection bar for electrically connecting them is connected. At an intermediate position of the second connection bar, an output wiring terminal for electrically connecting to an input terminal of an RF power supply is provided. The coil structure according to claim 4, characterized in that.

6. The M / 4 first connection bars are evenly distributed in the circumferential direction of the planar coil, the M / 4 second connection bars are evenly distributed in the circumferential direction of the planar coil, the diameter of the circle where the M / 4 first connection bars are located is the same as the diameter of the circle where the M / 4 second connection bars are located, and the M / 4 first connection bars and the M / 4 second connection bars are offset from each other in the circumferential direction of the planar coil. The coil structure according to claim 5, characterized in that.

7. N is equal to 4, and the number of turns of the planar coil in each layer is 0.25 turns. The coil structure according to any one of claims 1 to 6, characterized in that.

8. There are a plurality of the coil units, and the coil groups of the plurality of coil units have different dimensions and are provided nested with each other. The coil structure according to any one of claims 1 to 6, characterized in that.

9. There are two coil units, namely a first coil unit and a second coil unit respectively. The outer diameter of the second coil unit is smaller than the inner diameter of the first coil unit. The number of layers of the planar coil in the coil group of the first coil unit and the number of layers of the planar coil in the coil group of the second coil unit are set based on the magnitude of the power supplied by each, according to the coil structure of claim 8.

10. The coil structure according to any one of claims 1 to 6, characterized in that the distance between two adjacent layers of the planar coil is 10 mm or less.

11. The coil structure according to any one of claims 1 to 6, characterized in that the number of the coil groups is 4 or more and 64 or less.

12. The coil structure according to any one of claims 1 to 6, characterized in that the height of the planar coil in a direction perpendicular to the plane in which the planar coil is located is 2 mm or more and 15 mm or less.

13. Including a first coil structure and a second coil structure nested with each other, the first coil structure adopts the coil structure according to any one of claims 1 to 12, The second coil structure includes two layers of planar coils connected in series end-to-end in parallel with each other, and the orthographic projection of the two layers of planar coils on the plane where the planar coils are located is mirror-symmetrical, according to the coil structure.

14. An RF source, a reaction chamber, and the coil structure according to any one of claims 1 to 12, or the coil structure according to claim 13, wherein a dielectric window is provided at the top of the reaction chamber, the coil structure is provided above the dielectric window, and the RF source is used to supply RF power to the coil structure, according to the semiconductor processing apparatus.

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