Coil structure for generating plasma and semiconductor process apparatus

Abstract

This invention provides a coil structure and semiconductor process equipment for generating plasma. In this coil structure, each coil unit includes M coil groups, where M is an integer greater than or equal to 4. The M coil groups have identical structures and are connected in parallel. The planar coils in each of the M coil groups are arranged in a corresponding order on the same layer, and the M planar coils on the same layer are spaced apart and uniformly distributed along the circumferential direction of the planar coils. Each coil group includes N parallel layers of planar coils, where N is an even number greater than or equal to 4. The N layers of planar coils are spaced apart along a direction perpendicular to the plane containing the planar coils and are connected end-to-end in series. The orthographic projections of any two adjacent layers of planar coils onto the plane containing the planar coils are mirror-symmetrical. This invention improves the uniformity of the radial and angular distribution of the coupling energy generated below the coils and enhances the overall withstand voltage capability of the coils, thereby enabling high-power feeding.

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 semiconductor process equipment and semiconductor process equipment. Background Technology

[0002] Inductively coupled plasma (ICP) sources are used in the semiconductor field.

[0003] ICP (Integrated Plasma Processing) is a commonly used plasma source for dry etching and thin film deposition. It generates plasma by using a high-frequency electromagnetic field produced by a high-frequency current passing through a coil to excite gas. It can operate at relatively low chamber pressures and features high plasma density and minimal damage to the workpiece. As feature sizes continue to shrink, the challenges in the manufacturing 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.

[0004] Figure 1 This is a schematic diagram of an existing coil structure. Figure 2A for Figure 1 The projection of the coil structure onto its radial section. (See diagram below.) Figure 1 and Figure 2A 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.

[0005] like Figure 2A As shown, the shape of a single planar coil is an involute, and this involute is...

[0006] Taking 1.5 turns as an example, the involute curve is located at... Figure 2A 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

[0007] This invention aims to solve at least one of the technical problems existing in the prior art, and proposes a coil structure for generating plasma in a semiconductor process equipment and a semiconductor process equipment. It can compensate for the difference in current distribution in the radial direction of the coil, improve the uniformity of the distribution of coupling energy generated below the coil in the radial and angular directions, thereby improving the uniformity of the distribution of free radicals and ion density in the plasma in the radial direction, and improve the overall withstand voltage capability of the coil, thereby enabling high power feeding.

[0008] 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 unit, and each coil unit includes M coil groups, where M is an integer greater than or equal to 4. The M coil groups have the same structure and are connected in parallel.

[0009] Each coil group includes N parallel planar coils, where N is an even number greater than or equal to 4; the N planar coils are spaced apart along a direction perpendicular to the plane in which the planar coils are located, and are connected in series end to end; the orthographic projections of each two adjacent planar coils on the plane in which the planar coils are located are mirror-symmetrical;

[0010] The planar coils in each of the M coil groups are arranged in a one-to-one correspondence on the same layer, and the M planar coils located on the same layer are spaced apart from each other along the circumferential direction of the planar coils and are evenly distributed.

[0011] Optionally, M is an even number greater than or equal to 4;

[0012] The input terminals of the M coil groups are arranged on the same layer, and the planar coil is divided into M / 2 input terminal groups in the circumferential direction. Each input terminal group includes the input terminals of two adjacent coil groups, and a first extension section is connected between the input terminals of the two adjacent coil groups to connect them in parallel; the first extension sections in the M / 2 input terminal groups are connected in parallel.

[0013] The output terminals of the M coil groups are arranged on the same layer, and the planar coil is divided into M / 2 output terminal groups in the circumferential direction. Each output terminal group includes the output terminals of two adjacent coil groups, and a second extension section is connected between the output terminals of the two adjacent coil groups to connect them in parallel. The second extension sections in the M / 2 output terminal groups are connected in parallel.

[0014] Optionally, the extension direction of the first extension segment is consistent with the extension direction of the planar coil connected to the first extension segment in one of the coil groups;

[0015] The extension direction of the second extension segment is consistent with the extension direction of the planar coil connected to the second extension segment in one of the coil groups.

[0016] Optionally, a first terminal block for electrical connection to the output terminal of the RF power supply is provided at the middle position of the first extension section; and a second terminal block for electrical connection to the input terminal of the RF power supply is provided at the middle position of the second extension section.

[0017] Optionally, M / 2 of the first terminals are divided into M / 4 first terminal groups in the circumferential direction of the planar coil. Each first terminal group includes two adjacent first terminals, and a first connecting strip is connected between the two adjacent first terminals to connect them in parallel. An input terminal for electrical connection to the output terminal of the RF power supply is provided in the middle of the first connecting strip.

[0018] M / 2 of the second terminals are divided into M / 4 second terminal groups in the circumferential direction of the planar coil. Each second terminal group includes two adjacent second terminals, and a second connecting strip is connected between the two adjacent second terminals to connect them in parallel. An output terminal for electrical connection to the input terminal of the RF power supply is provided in the middle of the second connecting strip.

[0019] Optionally, M / 4 of the first connecting strips are evenly distributed in the circumferential direction of the planar coil, and M / 4 of the second connecting strips are evenly distributed in the circumferential direction of the planar coil. The diameters of the circumferences of the M / 4 first connecting strips and the circumferences of the M / 4 second connecting strips are the same, and the M / 4 first connecting strips and the M / 4 second connecting strips are staggered from each other.

[0020] Optionally, N equals 4, and the number of turns of each layer of the planar coil is 0.25 turns.

[0021] Optionally, there are multiple coil units, and the coil groups in the multiple coil units have different sizes and are nested together.

[0022] Optionally, there are two coil units, namely a first coil unit and a second coil unit, wherein the outer diameter of the second coil unit is smaller than the inner diameter of the first coil unit;

[0023] The number of layers of the coil group in the first coil unit and the number of layers of the coil group in the second coil unit are set based on the respective power input.

[0024] Optionally, the coil structure includes a first coil unit and a second coil unit, wherein the outer diameter of the second coil unit is smaller than the inner diameter of the first coil unit, and they are nested together; one of the first coil unit and the second coil unit includes at least one of the coil groups; the other of the first coil unit and the second coil unit includes two layers of planar coils that are parallel to each other.

[0025] Optionally, the spacing between any two adjacent planar coil layers is less than or equal to 10 mm.

[0026] Optionally, the number of coil groups is greater than or equal to 4 and less than or equal to 64.

[0027] Optionally, the height of the planar coil in the direction perpendicular to the plane in which the planar coil is located is greater than or equal to 2 mm and less than or equal to 15 mm.

[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] The beneficial effects of this invention are:

[0030] The present invention provides a coil structure for generating plasma in a semiconductor process apparatus, comprising M coil groups, where M is an integer greater than or equal to 4; the M coil groups are identical in shape and connected in parallel; the planar coils in each of the M coil groups are arranged in the same layer in a one-to-one correspondence; and the M planar coils located in the same layer are spaced apart from each other along the circumferential direction of the planar coil and are uniformly distributed. This gives the M coil groups angular symmetry in the circumferential direction of the planar coil, that is, they are symmetrical in the circumferential direction of the planar coil, thereby avoiding differences in current distribution in the circumferential direction, and thus improving the angular distribution uniformity of plasma density and improving process uniformity.

[0031] Furthermore, each coil group comprises N parallel planar coil layers, where N is an even number greater than or equal to 4. These N planar coil layers are spaced apart along a direction perpendicular to the plane containing the coils and connected end-to-end in series. The orthographic projections of any two adjacent planar coil layers onto the plane containing the coils are mirror-symmetrical. By making adjacent planar coil layers mirror-symmetrical, the magnetic and electric fields generated by one layer and its adjacent layer can compensate for each other. This compensates for differences in radial current distribution within the coils, improves the radial uniformity of the coupling energy generated below the coils, and consequently improves the radial uniformity of the free radical and ion density distribution in the plasma, thus enhancing process uniformity.

[0032] Meanwhile, by arranging an even number of planar coils (4 or more layers) at intervals along a direction perpendicular to the plane in which the planar coils are located, the distance between the input and output ends of the coil group can be increased (i.e., the distance between the uppermost and lowermost planar coils). At the same time, since the total voltage applied by the RF power supply to the input and output ends of the coil group is constant, the voltage borne by each layer of planar coil is only 1 / N of the total voltage, which can improve the overall withstand voltage capability of the coil group and achieve high power feeding while meeting the requirements of process uniformity.

[0033] The semiconductor process equipment provided by the present invention, by adopting the above-mentioned coil structure provided by the present invention, can not only 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 and angular distribution of free radicals and ion density in the plasma, but also improve the overall withstand voltage capability of the coil, thereby enabling high-power feeding. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of an existing coil structure;

[0035] Figure 2A This is a schematic diagram of electromagnetic field distribution in the prior art;

[0036] Figure 2B for Figure 1 The projection of the coil structure in the image onto its radial section;

[0037] Figure 3A This is a schematic diagram of a double-layer coil structure;

[0038] Figure 3B This is a schematic diagram of another type of double-layer coil structure;

[0039] Figure 4A A schematic diagram of the coil structure provided in an embodiment of the present invention;

[0040] Figure 4B A perspective view of a group of coils for a coil structure provided in an embodiment of the present invention;

[0041] Figure 5 Another perspective view of a set of coil groups for a coil structure provided in an embodiment of the present invention;

[0042] Figure 6 A top view of a group of coils in a coil structure provided in an embodiment of the present invention;

[0043] Figure 7 for Figure 6 Side view in the A1 direction;

[0044] Figure 8 for Figure 6 Side view in the A2 direction;

[0045] Figure 9A A 3D diagram showing two sets of coils with different numbers of turns;

[0046] Figure 9B A perspective view of four coil groups of the coil structure provided in an embodiment of the present invention;

[0047] Figure 10 A top view of four coil groups of the coil structure provided in an embodiment of the present invention;

[0048] Figure 11 for Figure 10 Side view in the A1 direction;

[0049] Figure 12 for Figure 10 Side view in the A2 direction;

[0050] Figure 13 A perspective view of sixteen coil groups provided in an embodiment of the present invention;

[0051] Figure 14 A top view of sixteen coil groups of a coil structure provided in an embodiment of the present invention;

[0052] Figure 15 for Figure 13 A three-dimensional diagram of two of the sixteen coil groups in the middle;

[0053] Figure 16 for Figure 13 Top view of two of the sixteen coil groups;

[0054] Figure 17 A top view of sixteen coil groups and a first connecting strip and a second connecting strip provided in an embodiment of the present invention;

[0055] Figure 18 Another top view of the sixteen coil groups, the first connecting strip, and the second connecting strip provided in the embodiment of the present invention;

[0056] Figure 19 A schematic diagram of a first coil unit and a second coil unit provided in an embodiment of the present invention;

[0057] Figure 20 Another schematic diagram of the first coil unit and the second coil unit of the coil structure provided in the embodiment of the present invention;

[0058] Figure 21A schematic diagram of another structure of the first coil unit and the second coil unit provided in the embodiments of the present invention;

[0059] Figure 22 This is a schematic diagram of the structure of a semiconductor process equipment provided in an embodiment of the present invention. Detailed Implementation

[0060] 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.

[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 comprises M coil groups, where M is an integer greater than or equal to 4. Each coil group includes N parallel planar coil layers, where N is an even number greater than or equal to 4. The N planar coil layers are spaced apart along a direction perpendicular to the plane containing the planar coil and are connected end-to-end in sequence. The orthographic projections of any two adjacent planar coil layers onto the plane containing the planar coil are mirror images. A mirror image means that the orthographic projections of one planar coil layer onto the plane containing the planar coil (hereinafter referred to as first projection A) and the orthographic projections of the other planar coil layer onto the plane containing the planar coil (hereinafter referred to as second projection B) have the same shape, but opposite spiral directions. Specifically, both first projection A and second projection B have front and back sides parallel to the plane containing the planar coil, and the front shape of one of the first projection A and second projection B is identical to that of the first projection A.

[0063] The reverse side shape of the first projection A is identical to that of the other projection B in the second projection B. Symmetry means that all parameters of the frontal shape of the first projection A and the reverse side shape of the other projection A and the second projection B are exactly the same.

[0064] By making two adjacent planar coil layers mirror symmetrical, the magnetic and electric fields generated by one planar coil layer and the adjacent planar coil layer can compensate for each other. This 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, and improving the uniformity of the process.

[0065] As a comparative embodiment of the present invention, please refer to Figure 3AThe coil structure 03 is electrically connected to the RF power supply 1 via the matching adapter 2, and 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. The two units have the same structure but different dimensions. 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, which are spaced apart in the vertical direction and connected in series. The orthographic projections of the first planar coil 031 and the second planar coil 032 onto the plane containing the planar coils are mirror-symmetrical. Although this can compensate for the difference in current distribution in the radial direction of the coil and improve the uniformity of the radial distribution of the coupling energy generated below the coil, in order to avoid the failure of the compensation effect for the difference in current distribution between the first sub-coil group and the second sub-coil group, the vertical spacing D1 between the first planar coil 031 and the second planar coil 032 cannot be too large (for example, when it is less than or equal to 10mm, the process uniformity is less than or equal to 1%). This makes the withstand voltage capability of the coil structure 03 low (less than or equal to 4kV), resulting in the maximum allowable feed power of the coil structure 03 being 2KW, which cannot be applied to high power (greater than 5KW) feed processes.

[0066] Please see Figure 3B Another coil structure 03', compared with the above-mentioned coil structure 03, increases the vertical spacing between the first planar coil 031 and the second planar coil 032 to D2, which is, for example, 30mm. Although the withstand voltage of this coil structure 03' is improved to above 12KV and can be applied to high-power (greater than 5KW) fed processes, the compensation effect of the difference in current distribution between the first sub-coil group and the second sub-coil group fails, and the process uniformity deteriorates from 1% to 2.7%, which cannot meet the process uniformity requirements (less than or equal to 1.5%).

[0067] To resolve the above issues, please refer to Figure 4A The coil structure 3 provided in this embodiment of the invention includes at least one coil unit, each coil unit including M coil groups, where M is an integer greater than or equal to 4; the coil groups in the multiple coil units have different sizes and are nested together. For example, Figure 4A The diagram shows two coil units, namely a first coil unit 3a and a second coil unit 3b. 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 together. Of course, the embodiments of the present invention are not limited to this. In practical applications, depending on specific needs, there may be only one coil unit, or there may be more than three.

[0068] The first coil unit 3a and the second coil unit 3b have the same structure. Taking the first coil unit 3a as an example, it includes M coil groups. Each coil group includes N parallel planar coils, where N is an even number greater than or equal to 4. Taking N=4 as an example, the four planar coils are, 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 planar coils are arranged along a direction perpendicular to the plane in which the planar coil is located (i.e., Figure 4A The planar coils are spaced vertically and connected end-to-end in sequence, thus achieving N layers of interconnected planar coils; the orthographic projections of any two adjacent planar coil layers onto the plane containing the planar coils are mirror images of each other. It should be noted that... Figure 4A The planar coil is only shown schematically with a "mouth" symbol and does not represent the specific structure of the planar coil.

[0069] By including N parallel planar coils in the coil group, where N is an even number greater than or equal to 4, that is, the coil group has an even number of planar coils with 4 or more layers, this is relative to the above. Figure 3A The coil structure 03 shown can increase the vertical spacing D5 between the input and output ends of the coil group, that is, the spacing between the uppermost first planar coil 31 and the lowermost fourth planar coil 34. This spacing D5 is, for example, greater than or equal to 30mm. This can increase the withstand voltage between the uppermost first planar coil 31 and the lowermost fourth planar coil 34 to more than 12KV, which can be applied to high power (greater than 5KW) feeding processes. Meanwhile, since a second planar coil 32 is positioned below the uppermost first planar coil 31, and the second planar coil 32 and the first planar coil 31 are mirror images of each other on the plane of the planar coils (i.e., they have the same shape but opposite spiral directions), the magnetic and electric fields they generate can compensate for each other. Specifically, the distribution of the total magnetic and electric fields formed by the superposition of the magnetic and electric fields generated by the second planar coil 32 and the first planar coil 31 is mirror-symmetrical, thus compensating for the radial current distribution differences among the planar coils. Similarly, a third planar coil 33 is positioned above the lowermost fourth planar coil 34, and the third planar coil 33 and the fourth planar coil 34 are mirror images of each other on the plane of the planar coils, allowing their magnetic and electric fields to compensate for each other. Furthermore, the mirror-symmetrical projections of the adjacent second planar coil 32 and third planar coil 33 on the plane of the planar coils further enable mutual compensation of their magnetic and electric fields. This allows for compensation of radial current distribution differences among planar coils, improving the radial uniformity of coupling energy generated below the coils, thereby enhancing the radial uniformity of free radical and ion density distribution in the plasma and improving process uniformity.

[0070] Based on this, by arranging an even number of planar coils (4 layers or more) at intervals along a direction perpendicular to the plane containing the planar coils, this is consistent with... Figure 3A Compared to coil structure 03, the spacing between the input and output ends of the coil group (i.e., the spacing between the uppermost and lowermost planar coils) D5 can be increased. This spacing D5 can be increased to, for example, 30mm or more. Simultaneously, the spacing between the uppermost first planar coil 31 and its adjacent second planar coil 32, and the spacing between the lowermost fourth planar coil 34 and its adjacent third planar coil 33, are both D2. The spacing between adjacent second planar coils 32 and third planar coils 33 is D3. Both D2 and D3 are, for example, less than or equal to 10mm. This ensures that the compensation effect of adjacent planar coils on current distribution differences does not fail, thus guaranteeing that process uniformity requirements are met. Furthermore, since the total voltage applied by the RF power supply 1 to the input and output ends of the coil group through the matching unit 2 is constant, the voltage borne by each planar coil layer is only 1 / N of the total voltage. This improves the overall withstand voltage capability of the coil group, thereby achieving high-power feeding while meeting process uniformity requirements.

[0071] It should be noted that in practical applications, the number of planar coil layers, i.e., the value of N, can be set according to specific needs. The greater the power input, the greater the distance between the input and output ends of the coil group (i.e., the distance between the uppermost and lowermost planar coils), and the larger the value of N will be.

[0072] It should also be noted that the spacing between any two adjacent planar coil layers should not be too large to ensure that the compensation effect of the two adjacent planar coil layers on the current distribution difference does not fail, nor should it be too small to avoid arcing caused by the close proximity of the two adjacent planar coil layers. Optionally, the spacing between any two adjacent planar coil layers should be less than or equal to 10mm, such as 5mm, 7mm, etc.

[0073] In some alternative embodiments, the shape of each layer of planar coils is a helical involute.

[0074] In some optional embodiments, the height of each planar coil layer in the direction perpendicular to the plane in which the planar coil is located is greater than or equal to 2 mm and less than or equal to 15 mm.

[0075] In some optional embodiments, the number of turns in each layer of planar coils can be set according to the required inductance. The greater the required inductance, the more turns are needed. Specifically, the inductance is proportional to the square of the number of turns. The number of turns in planar coils of different layers is the same. In addition, the number of turns in each layer of planar coils should not be too many, otherwise it will limit the number of coil groups (i.e., the value of M) due to the large amount of space occupied in the circumferential direction. Preferably, N=4, and the number of turns in each layer of planar coils is 0.25 turns. In this way, the total number of turns in 4 layers of planar coils is 1 turn, that is, one revolution in the circumferential direction.

[0076] In one specific embodiment, please refer to Figure 4B Taking the first coil unit 3a as an example, N=4, and each layer of planar coils has 2 turns. The four layers of planar coils, from top to bottom, are the first planar coil 31, the second planar coil 32, the third planar coil 33, and the fourth planar coil 34. The four layers of planar coils are spaced apart along a direction perpendicular to the plane in which the planar coil is located, and are connected in series end to end. Specifically, each pair of adjacent planar coils is connected in series through a connecting post 4, and is electrically conductive. This connecting post 4 is, for example, arranged along a 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 the two ends of the uppermost first planar coil 31 and the lowermost fourth planar coil 34 that are close to each other, respectively. Each of the four layers of planar coils is a spiral involute with the same parameters, and the spiral directions of adjacent layers of planar coils are opposite. Specifically, on a plane perpendicular to the plane coil, from a top-down view, the spiral direction of the first plane coil 31 is clockwise, while the spiral direction of the adjacent second plane coil 32 is counterclockwise, and the two are mirror images of each other; the spiral direction of the third plane coil 33 adjacent to the second plane coil 32 is clockwise, that is, the third plane coil 33 is mirror images of the second plane coil 32, and coincides with the first plane coil 31; the spiral direction of the fourth plane coil 34 adjacent to the third plane coil 33 is counterclockwise, that is, the fourth plane coil 34 is mirror images of the third plane coil 33, and coincides with the second plane coil 32.

[0077] In another specific embodiment, please refer to [the relevant document / reference]. Figures 5 to 8 Taking the first coil unit 3a as an example, N=4, and the number of turns of each layer of planar coils is 0.25 turns. The four layers of planar coils, from top to bottom, are the first planar coil 31, the second planar coil 32, the third planar coil 33, and the fourth planar coil 34; the four layers of planar coils are arranged along a direction perpendicular to the plane in which the planar coil is located (i.e., Figure 7The planar coils are spaced apart in the Z direction and connected in series, specifically, each pair of adjacent planar coils is connected in series via a connecting post 4, which is electrically conductive. This connecting post 4 is, for example, positioned perpendicular to the plane of the planar coil. The input terminal 31a and output terminal 31b of the coil group are the two ends of the uppermost first planar coil 31 and the lowermost fourth planar coil 34, respectively, close to each other. Each of the four planar coils is a spiral involute with identical parameters, and the spiral directions of adjacent planar coils are opposite. Specifically, as shown... Figure 6 As shown, the first planar coil 31 and the second planar coil 32 are symmetrical with respect to the second axis O2 on the plane parallel to the plane coil (with opposite spiral directions); the second planar coil 32 and the third planar coil 33 are symmetrical with respect to the first axis O1 on the plane parallel to the plane coil (with opposite spiral directions); the third planar coil 33 and the fourth planar coil 34 are symmetrical with respect to the second axis O2 on the plane parallel to the plane coil (with opposite spiral directions).

[0078] like Figure 8 As shown, the vertical distance D5 between the input terminal 31a and the output terminal 31b of the coil group is equal to twice the distance D3, the distance D4, and the sum of 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 a distance D3 and a distance D4 of 7 mm as examples, and a height H1 and a height H2 of 5 mm as examples, the distance D5 is 31 mm, which can meet the process requirements for the withstand voltage of the coil structure.

[0079] 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 2B 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.

[0080] To solve the aforementioned technical problems, the coil groups are designed to consist of M coils, where M is an integer greater than or equal to 4. These M coil groups have identical structures and are connected in parallel. The planar coils in each of the M coil groups are arranged in a one-to-one correspondence within the same layer, and the M planar coils on the same layer are spaced apart and evenly distributed along the circumferential direction of the planar coils. In other words, the M planar coils on the same layer are arranged at different rotation angles along the circumferential direction. Specifically, taking M=4 as an example, please refer to [further details omitted]. Figures 9B to 12 The four coil groups are designated as first coil group 3a1, second coil group 3a2, third coil group 3a3, and fourth coil group 3a4. Each of the four coil groups comprises N layers of planar coils that are parallel to each other (e.g., N=4). Figure 5 Taking the illustrated four-layer planar coil as an example, in the M coil groups, M first planar coils 31 are arranged in the same layer, spaced apart from each other along the circumference of the planar coil, and evenly distributed; M second planar coils 32 are arranged in the same layer, spaced apart from each other along the circumference of the planar coil, and evenly distributed; M third planar coils 33 are arranged in the same layer, spaced apart from each other along the circumference of the planar coil, and evenly distributed; M fourth planar coils 34 are arranged in the same layer, spaced apart from each other along the circumference of the planar coil, and evenly distributed. In other words, after any coil group is rotated a certain angle clockwise or counterclockwise along the circumference of the planar coil, it will coincide with another adjacent coil group. For example, Figure 9B The diagram shows four coil groups. In this case, taking the first coil group 3a1 as an example, after rotating 90° clockwise or counterclockwise along the circumference of the planar coil, it will coincide with another adjacent coil group (e.g., the second coil group 3a2 or the fourth coil group 3a4). It is easy to understand that in the M coil groups, since the M planar coils arranged in the same layer are distributed on the same circumference, the first and second ends of the M planar coils are located on two concentric circles, respectively.

[0081] Since the M coil groups have the same shape and can be evenly distributed along the circumference of the planar coil, the M planar coils corresponding to each layer of the M coil groups can jointly form an approximate circle along the circumference of the planar coil. This gives the M coil groups angular symmetry along the circumference of the planar coil, that is, they are symmetrical along the circumference of the planar coil. This avoids differences in current distribution along the circumference, thereby improving the angular distribution uniformity of plasma density and improving process uniformity.

[0082] It should be noted that if there are fewer than 4 coil groups, for example... Figure 9AFigures (a) and (b) show coil structures with two coil groups. Figure (a) shows that each coil group has only one planar coil per layer, resulting in asymmetrical current distribution in the circumferential direction (i.e., angular direction) of the planar coil. Figure (b) shows that each coil group has two planar coils per layer. Although the number of planar coils increases, the two planar coils in the same layer are mirror-symmetrical, making the coil structure shown in Figure (b) still asymmetrical in the circumferential direction (i.e., angular direction). The inventors discovered that only with four or more coil groups, and M planar coils in the same layer arranged at different rotation angles in the circumferential direction, can an approximate circle be formed to meet the process requirements for angular uniformity. Furthermore, the more coil groups there are, i.e., the larger the value of M, the better the angular uniformity. Preferably, M = 4, 8, or 16.

[0083] In other alternative embodiments, please refer to [the document / reference]. Figure 13 and Figure 14 M = 16, and the 16 coil groups are designated as the first coil group 3a1 to the sixteenth coil group 3a16. It should be noted that the more coil groups there are, i.e., the larger the value of M, the better the angular symmetry of the coil structure composed of M coil groups, which is more conducive to improving the angular distribution symmetry of the plasma density. In some preferred embodiments, the number of coil groups (i.e., the value of M) is greater than or equal to 2 and less than or equal to 64.

[0084] In some optional embodiments, the M coil groups are connected in parallel to each other in the following ways: the input and output ends of each coil group (i.e., the two ends of the uppermost planar coil and the lowermost planar coil that are close to each other) are electrically connected to the input and output ends of the RF power supply 1 through the matching unit 2, respectively. Optionally, to reduce the number of terminals in the RF power supply 1, M is an even number greater than or equal to 2; the input terminals of the M coil groups are arranged on the same layer (all located on the top or bottom layer), and are divided into M / 2 input terminal groups (pairs of two) in the circumferential direction of the planar coil. Each input terminal group includes the input terminals of two adjacent coil groups, and a first extension section is connected between the input terminals of the two adjacent coil groups to connect them in parallel; the first extension sections in the M / 2 input terminal groups are connected in parallel; similarly, the output terminals of the M coil groups are arranged on the same layer (all located on the bottom or top layer), and are divided into M / 2 output terminal groups (pairs of two) in the circumferential direction of the planar coil. Each output terminal group includes the output terminals of two adjacent coil groups, and a second extension section is connected between the output terminals of the two adjacent coil groups to connect them in parallel; the second extension sections in the M / 2 output terminal groups are connected in parallel.

[0085] Taking M=16 as an example, the input terminals of the 16 coil groups are arranged on the same layer, and the planar coil is divided into 8 input terminal groups in the circumferential direction. Each input terminal group includes the input terminals of two adjacent coil groups. Figure 15 and Figure 16 The diagram shows the input terminals 31a of two adjacent coil groups (3a1, 3a2) out of sixteen coil groups. A first extension segment 5a connects the input terminals 31a of the two adjacent coil groups (3a1, 3a2) to connect them in parallel; furthermore, this first extension segment 5a is connected in parallel with another adjacent first extension segment 5a. Similarly, Figure 15 and Figure 16 The output terminals 31b of two adjacent coil groups (3a1, 3a2) of the sixteen coil groups are shown. A second extension 5b is connected between the output terminals 31b of the two adjacent coil groups (3a1, 3a2) to connect them in parallel. Furthermore, the second extension 5b is connected in parallel with another adjacent second extension 5b.

[0086] In some alternative embodiments, such as Figure 15 As shown, the extending direction of the first extension segment 5a is consistent with the extending direction of the planar coil connected to the first extension segment 5a in one of the coil groups, for example, Figure 15 In the first extension segment 5a, the extension direction is consistent with that of the planar coil (e.g., the uppermost planar coil) connected to the first coil group 3a1; the extension direction of the second extension segment 5b is consistent with the extension direction of the planar coil connected to the second extension segment 5b in one of the coil groups, for example, Figure 15 In the second extension segment 5b, the extension direction is consistent with that of the planar coil (e.g., the lowest planar coil) connected to the second coil group 3a2.

[0087] In some alternative embodiments, such as Figure 15 As shown, a first terminal 51a for electrical connection to the output terminal of the RF power supply 1 is provided at the middle position of the first extension section 5a; a second terminal 51b for electrical connection to the input terminal of the RF power supply 1 is provided at the middle position of the second extension section 5b. In this way, the total length of the two adjacent coil groups can be the same, so that the current can flow through the two coil groups in the same path.

[0088] It should be noted that the M coil groups can be connected in parallel in any other way. For example, the input terminals of the M coil groups can be directly connected in parallel, and the output terminals of the M coil groups can be directly connected in parallel.

[0089] In some optional embodiments, to further reduce the number of terminals of the RF power supply 1, M / 2 first terminals 51a are divided into M / 4 first terminal groups (pairs of two) in the circumferential direction of the planar coil. Each first terminal group includes two adjacent first terminals 51a, and a first connecting strip 6a connects the two adjacent first terminals 51a to connect them in parallel. An input terminal 61a for electrical connection to the output terminal of the RF power supply 1 is provided at the middle position of the first connecting strip 6a. Similarly, M / 2 second terminals 51b are divided into M / 4 second terminal groups (pairs of two) in the circumferential direction of the planar coil. Each second terminal group includes two adjacent second terminals 51b, and a second connecting strip 6b connects the two adjacent second terminals 51b to connect them in parallel. An output terminal 61b for electrical connection to the input terminal of the RF power supply 1 is provided at the middle position of the second connecting strip 6b. Taking M=16 as an example, the eight first terminals 51a are divided into four first terminal groups in the circumferential direction of the planar coil; the eight second terminals 51b are divided into four second terminal groups in the circumferential direction of the planar coil.

[0090] In some alternative embodiments, to ensure the symmetry of the coil structure in its circumferential direction, such as... Figure 17 As shown, M / 4 first connecting strips 6a are evenly distributed along the circumference of the planar coil, and M / 4 second connecting strips 6b are also evenly distributed along the circumference of the planar coil. The diameters of the circumferences containing the M / 4 first connecting strips 6a and the M / 4 second connecting strips 6b are the same, and the M / 4 first connecting strips 6a and M / 4 second connecting strips 6b are staggered, i.e., they are arranged opposite each other along the circumference of the planar coil. By staggering the M / 4 first connecting strips 6a and M / 4 second connecting strips 6b, the wiring layout between the RF power supply and the connecting strips can be designed more conveniently. Of course, the embodiments of the present invention are not limited to this; for example, as... Figure 18 As shown, M / 4 first connecting strips 6a and M / 4 second connecting strips 6b can also overlap one-to-one in a direction perpendicular to the plane where the planar coil is located.

[0091] In some alternative embodiments, the coil structure 3 includes multiple coil units, the coil groups within the multiple coil units being of different sizes and nested together. For example, Figure 19 The diagram shows two coil units, namely a first coil unit 3a and a second coil unit 3b. 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 together.

[0092] Optionally, the number of coil layers in the first coil unit 3a is the same as the number of coil layers in the second coil unit 3b, for example, both are 4 layers. However, the embodiments of the present invention are not limited to this. Depending on the power ratio of the first coil unit 3a and the second coil unit 3b, the number of coil layers in the first coil unit 3a and the second coil unit 3b can also be different. Specifically, the greater the input power, the more layers there are; conversely, the smaller the input power, the fewer layers there are.

[0093] In another alternative embodiment, such as Figure 20 As shown, the coil structure can also include two coil units, namely a first coil unit 3a and a second coil unit 3b'. 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 together. The first coil unit 3a includes at least one coil group comprising N parallel planar coils, where N is an even number greater than or equal to 4. The coil group in the second coil unit 3b' comprises two parallel planar coils. This design can be applied to situations where the power fed into the inner coil is relatively small (less than or equal to 4kV). Similarly, as... Figure 21 As shown, the coil structure can also include two coil units, namely a first coil unit 3a' and a second coil unit 3b. 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 together. The second coil unit 3b consists of N parallel planar coils, where N is an even number greater than or equal to 4; the first coil unit 3a' consists of two parallel planar coils. This design can be applied to situations where the power fed into the outer coil is relatively small (less than or equal to 4kV).

[0094] As another technical solution, this embodiment also provides a semiconductor process apparatus, for example, such as... Figure 22 As shown, the semiconductor process equipment includes an RF power supply 1 for the upper electrode, a matching unit 2, a reaction chamber 100, and a coil structure 3. A dielectric window 101 is disposed at the top of the reaction chamber 100, and the coil structure 3 is disposed above the dielectric window 101. The coil structure 3 adopts the coil structure provided in the above embodiments of the present invention, for example, using... Figure 4A The coil structure shown is 3.

[0095] Radio frequency (RF) power supply 1 provides RF power to coil structure 3 via matching converter 2 to excite the process gas in reaction chamber 100 to form plasma. Additionally, a base 102 is disposed in reaction chamber 100 to support the wafer, and the base 102 is electrically connected to RF source 103 at the lower electrode. RF source 103 applies RF bias to base 102 to attract plasma toward the wafer surface.

[0096] The semiconductor process equipment provided by the present invention, by adopting the above-mentioned coil structure provided by the present invention, can not only 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, but also improve the overall withstand voltage capability of the coil, thereby enabling high-power feeding.

[0097] 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 unit, and each coil unit includes M coil groups, where M is an integer greater than or equal to 4; the M coil groups have the same structure and are connected in parallel. Each coil group includes N parallel planar coils, where N is an even number greater than or equal to 4; the N planar coils are spaced apart along a direction perpendicular to the plane in which the planar coils are located, and are connected in series end to end; the orthographic projections of each two adjacent planar coils on the plane in which the planar coils are located are mirror-symmetrical; The planar coils in each of the M coil groups are arranged in a one-to-one correspondence on the same layer, and the M planar coils located on the same layer are spaced apart from each other along the circumferential direction of the planar coils and are evenly distributed.

2. The coil structure according to claim 1, characterized in that, M is an even number greater than or equal to 4; The input terminals of the M coil groups are arranged on the same layer, and the planar coil is divided into M / 2 input terminal groups in the circumferential direction. Each input terminal group includes the input terminals of two adjacent coil groups, and a first extension section is connected between the input terminals of the two adjacent coil groups to connect them in parallel; the first extension sections in the M / 2 input terminal groups are connected in parallel. The output terminals of the M coil groups are arranged on the same layer, and the planar coil is divided into M / 2 output terminal groups in the circumferential direction. Each output terminal group includes the output terminals of two adjacent coil groups, and a second extension section is connected between the output terminals of the two adjacent coil groups to connect them in parallel. The second extension sections in the M / 2 output terminal groups are connected in parallel.

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

4. The coil structure according to claim 2, characterized in that, The first extension section has a first terminal block for electrical connection to the output terminal of the RF power supply at its middle position; the second extension section has a second terminal block for electrical connection to the input terminal of the RF power supply at its middle position.

5. The coil structure according to claim 4, characterized in that, M / 2 of the first terminals are divided into M / 4 first terminal groups in the circumferential direction of the planar coil. Each first terminal group includes two adjacent first terminals, and a first connecting strip is connected between the two adjacent first terminals to connect them in parallel. An input terminal for electrical connection to the output terminal of the RF power supply is provided in the middle of the first connecting strip. M / 2 of the second terminals are divided into M / 4 second terminal groups in the circumferential direction of the planar coil. Each second terminal group includes two adjacent second terminals, and a second connecting strip is connected between the two adjacent second terminals to connect them in parallel. An output terminal for electrical connection to the input terminal of the RF power supply is provided in the middle of the second connecting strip.

6. The coil structure according to claim 5, characterized in that, M / 4 of the first connecting strips are evenly distributed in the circumferential direction of the planar coil, and M / 4 of the second connecting strips are evenly distributed in the circumferential direction of the planar coil. The diameters of the circumferences of the M / 4 first connecting strips and the circumferences of the M / 4 second connecting strips are the same, and the M / 4 first connecting strips and the M / 4 second connecting strips are staggered.

7. The coil structure according to any one of claims 1-6, characterized in that, The number of turns for each layer of the planar coil is 0.

25.

8. The coil structure according to any one of claims 1-6, characterized in that, There are multiple coil units, and the coil groups in the multiple coil units are of different sizes and are nested together.

9. The coil structure according to claim 8, characterized in that, The coil unit consists of two coil units, namely a first coil unit and a second coil unit, wherein 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 coil group in the first coil unit and the number of layers of the coil group in the second coil unit are set based on the respective power input.

10. The coil structure according to any one of claims 1-6, characterized in that, The coil structure includes a first coil unit and a second coil unit, wherein the outer diameter of the second coil unit is smaller than the inner diameter of the first coil unit, and they are nested together; one of the first coil unit and the second coil unit includes at least one coil group; the other of the first coil unit and the second coil unit includes two layers of planar coils that are parallel to each other.

11. The coil structure according to any one of claims 1-6, characterized in that, The spacing between any two adjacent planar coil layers is less than or equal to 10 mm.

12. The coil structure according to any one of claims 1-6, characterized in that, The number of coil groups is greater than or equal to 4 and less than or equal to 64.

13. The coil structure according to any one of claims 1-6, characterized in that, The height of the planar coil in the direction perpendicular to the plane in which the planar coil is located is greater than or equal to 2 mm and less than or equal to 15 mm.

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.

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