WO2023227095A1

WO2023227095A1 - Coil structure for generating plasma and semiconductor process device

Info

Publication number: WO2023227095A1
Application number: PCT/CN2023/096457
Authority: WO
Inventors: 赵晋荣; 茅兴飞; 王松; 姚卫杰; 杨纪鹏; 陈星�; 韦刚; 陈国动; 王伟; 李岩; 戴庚霖; 杨延铭
Original assignee: 北京北方华创微电子装备有限公司
Priority date: 2022-05-27
Filing date: 2023-05-26
Publication date: 2023-11-30
Also published as: TW202347419A; CN115497797A

Abstract

A coil structure for generating plasma, comprising at least one coil unit. Each coil unit comprises M coil groups, and M is an integer greater than or equal to 4; the M coil groups have the same structure and are connected in parallel to each other; each coil group comprises N layers of planar coils which are parallel to each other, and N is an even number greater than or equal to 4; the planar coils of each layer in the M coil groups are arranged in the same layer in one-to-one correspondence, and the M planar coils located in the same layer are spaced apart from each other in the circumferential direction of the planar coils, and are uniformly distributed; the N layers of planar coils in each coil group are arranged at intervals in a direction perpendicular to a plane where the planar coils are located, and are sequentially connected in series end to end; the orthographic projections of every two adjacent layers of planar coils on the plane where the planar coils are located are mirror-symmetrical. The coil structure can not only improve the distribution uniformity of coupling energy generated under the coils in the radial direction and the angular direction, but also improve the overall voltage endurance capability of the coils, thereby implementing high-power feed-in. Also disclosed is a semiconductor process device.

Description

Coil structures and semiconductor process equipment used to generate plasma

Technical field

The present invention relates to the field of semiconductor processing technology, and in particular, to a coil structure for generating plasma in semiconductor process equipment and semiconductor process equipment.

Background technique

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 uses a high-frequency electromagnetic field generated by a high-frequency current passing through a coil to excite gas to generate plasma. It can work at a lower chamber pressure and has the characteristics of high plasma density and little damage to the workpiece. As the feature scale shrinks, the challenges faced during processing become more and more severe. One of the very important requirements is the consistency of the plasma source. For ICP sources, the coil distribution affects the etching morphology and Its uniformity plays a key role, and it is necessary to continuously optimize the uniform symmetry of the radial and angular distribution of the coil current to further enhance the ability of plasma processing equipment to manufacture highly integrated device processes.

Figure 1 is a schematic diagram of an existing coil structure. FIG. 2A is a projection view of the coil structure in FIG. 1 on its radial cross-section. As shown in Figure 1 and Figure 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, and the two planar coils are 180° rotationally symmetrically distributed relative to their axial direction. The orthographic projection shape of each planar coil on its radial cross-section is an involute shape, and the number of coil turns is 1.5 turns. The outer ends of the two planar coils of the inner coil group 11 and the outer coil group 12 are connected in parallel on the outer ring and are electrically connected to the output end of the matcher 13. The inner ends of the inner coils are connected in parallel and are connected to the input of the matcher 13. terminal electrical connection.

As shown in Figure 2A, take the shape of a single planar coil as an involute, and the involute is 1.5 turns. The involute is located on the left and right sides of the dotted line shown in Figure 2A. The geometric distribution is uneven, resulting in asymmetric distribution of electromagnetic fields on the left and right sides, resulting in uneven currents on the left and right sides of the coil. At the same time, this will cause an asymmetric distribution of free radicals and ion density in the plasma during the process, which will lead to uneven plasma distribution, resulting in uneven etching of the wafer and adversely affecting the etching quality or efficiency.

Contents of the invention

The present invention aims to solve at least one of the technical problems existing in the prior art. It proposes a coil structure for generating plasma in semiconductor process equipment and a semiconductor process equipment, which can compensate for the difference in current distribution of the coil in the radial direction. , improve the distribution uniformity of the coupling energy generated under 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 improving the overall voltage resistance of the coil, thus High power feed can be achieved.

In order to achieve the above object, the present invention provides a coil structure for generating plasma in semiconductor process equipment. The coil structure includes at least one coil unit, each of the coil units includes M coil groups, and M is greater than An integer equal to 4; the M coil groups have the same structure and are connected in parallel; each coil group includes N layers of planar coils parallel to each other, and N is an even number greater than or equal to 4; among the M coil groups Each layer of the planar coils is arranged in the same layer in one-to-one correspondence, 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 evenly distributed;

The N layers of the planar coils in each coil group are spaced apart in a direction perpendicular to the plane where the planar coils are located, and are connected in series end to end; every two adjacent layers of the planar coils are arranged in a direction perpendicular to the plane where the planar coils are located. The orthographic projection on is mirror symmetrical.

Optionally, the 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 are divided into M/2 input terminal groups in the circumferential direction of the planar coil. Each input terminal group includes two adjacent coils. The input terminals of the M/2 input terminal groups, and a first extension section is connected between the input terminals of two adjacent coil groups to electrically connect the two; the first extension section in the M/2 input terminal groups Electrical connection between extension sections;

The output ends of the M coil groups are arranged on the same layer, and are drawn in the circumferential direction of the planar coils. Divided into M/2 output terminal groups, each of the output terminal groups includes the output terminals of two adjacent coil groups, and the output terminals of the two adjacent coil groups are connected to a third Two extension sections are used to electrically connect the two; the second extension sections in the M/2 output terminal groups are electrically connected to each other.

Optionally, the extension direction of the first extension section is consistent with the extension direction of the planar coil connected to the first extension section in one of the coil groups;

The extension direction of the second extension section is consistent with the extension direction of the planar coil connected to the second extension section in one of the coil groups.

Optionally, a first terminal for electrical connection with the output terminal of the radio frequency power supply is provided at the middle position of the first extension section; and an input terminal for electrical connection with the radio frequency power supply is provided at the middle position of the second extension section. Second terminal for electrical connection.

Optionally, the M/2 first terminals are divided into M/4 first terminal groups in the circumferential direction of the planar coil, and each of the first terminal groups includes two adjacent ones. The first connection terminals, and a first connection strip is connected between two adjacent first connection terminals for electrically connecting the two; a middle position of the first connection strip is provided with a radio frequency power supply. The output terminal is electrically connected to the input terminal block;

The M/2 second terminals are divided into M/4 second terminal groups in the circumferential direction of the planar coil, and each of the second terminal groups includes two adjacent second terminals. terminals, and a second connection strip is connected between two adjacent second connection terminals for electrically connecting the two; the middle position of the second connection strip is provided with an input terminal for electrical connection with the radio frequency power supply. Connect the output terminals.

Optionally, M/4 first connecting strips are evenly distributed in the circumferential direction of the planar coil, M/4 second connecting strips are evenly distributed in the circumferential direction of the planar coil, and M /4 of the first connecting bars have the same diameter as the circle of M/4 of the second connecting bars, and M/4 of the first connecting bars and M/4 of the second connecting bars The planar coils are staggered from each other in the circumferential direction.

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

Optionally, there are multiple coil units, and the coil groups in the multiple coil units have different sizes and are nested with each other.

Optionally, there are two coil units, namely a first coil unit and a second coil unit, and 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 of the coil group in the first coil unit and the number of layers of the planar coils of the coil group in the second coil unit are set based on the power levels fed in by each. Certainly.

As another technical solution, the present invention also provides a coil structure, including a first coil structure and a second coil structure nested in each other, wherein the first coil structure adopts the above-mentioned coil structure provided by the present invention;

The second coil structure includes two layers of planar coils that are parallel to each other and connected in series end to end. The orthographic projections of the two layers of planar coils on the plane where the planar coils are located are mirror symmetrical.

Optionally, the distance between each two adjacent layers of the planar coils is less than or equal to 10 mm.

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

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

As another technical solution, the present invention also provides a semiconductor process equipment, including a radio frequency source, a reaction chamber and the above-mentioned 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 provided with Above the dielectric window; the radio frequency source is used to provide radio frequency power to the coil structure.

Beneficial effects of the present invention:

The coil structure for generating plasma in semiconductor process equipment provided by the present invention includes M coil groups, where M is an integer greater than or equal to 4; the M coil groups have the same shape and are connected in parallel, and each coil group includes Parallel N-layer planar coils, N is an even number greater than or equal to 4; M lines Each layer of planar coils in the coil group is arranged in the same layer in one-to-one correspondence, and the M planar coils located on the same layer are spaced apart from each other along the circumferential direction of the planar coil and evenly distributed. This makes the M coil groups in the circumferential direction of the planar coil. It has angular symmetry, that is, it is symmetrical in the circumferential direction of the planar coil, which can avoid differences in current distribution in the circumferential direction, thereby improving the angular distribution uniformity of plasma density and improving process uniformity. .

Moreover, the N layers of planar coils in each coil group are spaced apart in a direction perpendicular to the plane where the planar coils are located, and are connected in series end to end; the orthographic projections of each two adjacent layers of planar coils in the plane of the planar coils are mirror symmetrical. . By making two adjacent layers of planar coils mirror symmetrical, the magnetic field and electric field generated by one of the planar coils and the other adjacent layer of planar coils can compensate each other, thereby compensating for the current distribution of the coils in the radial direction. The difference improves the radial distribution uniformity of the coupling energy generated under the coil, thereby improving the radial distribution uniformity of the free radical and ion density in the plasma and improving process uniformity.

At the same time, by having more than 4 layers of even-numbered planar coils in each coil group spaced apart in a direction perpendicular to the plane where the planar coils are located, the distance between the input end and the output end of the coil group can be increased (i.e., the uppermost layer (the distance between the planar coil and the bottom planar coil). At the same time, since the total voltage loaded by the RF power supply to the input and output ends of the coil group is certain, the voltage withheld by each layer of planar coils is only 1/N of the total voltage. , that is, the overall voltage withstand capability of the coil group can be improved, and high-power feed-in can be achieved on the basis of meeting the process uniformity requirements.

The present invention also provides a coil structure. By combining the above-mentioned coil structure provided by the present invention with two layers of planar coils parallel to each other, it can be applied to situations where the input power of the inner ring and the outer ring is different. That is, the present invention The above-mentioned coil structure provided by the invention can be applied to high-power feed (greater than 5kW), while the two-layer planar coils parallel and connected in series can be applied to low-power feed (less than or equal to 2kW), thereby meeting a variety of different process requirements. .

The semiconductor process equipment provided by the present invention, by adopting the above-mentioned coil structure provided by the present invention, can compensate for the difference in current distribution of the coil in the radial direction and improve the current distribution generated below the coil. The uniformity of the coupling energy distribution in the radial direction can improve the distribution uniformity of the free radical and ion density in the plasma in the radial and angular directions, and can also improve the overall voltage resistance of the coil, thus enabling high-power feed.

Description of the drawings

Figure 1 is a schematic diagram of an existing coil structure;

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

Figure 2B is a projection view of the coil structure in Figure 1 on its radial cross-section;

Figure 3A is a schematic structural diagram of a double-layer coil;

Figure 3B is a schematic structural diagram of another double-layer coil;

Figure 4A is a schematic diagram of a coil structure provided by an embodiment of the present invention;

Figure 4B is a perspective view of a coil group of the coil structure provided by the embodiment of the present invention;

Figure 5 is another perspective view of a coil group of the coil structure provided by the embodiment of the present invention;

Figure 6 is a top view of a coil group of the coil structure provided by the embodiment of the present invention;

Figure 7 is a side view from the A1 direction in Figure 6;

Figure 8 is a side view from the A2 direction in Figure 6;

Figure 9A is a perspective view of two sets of coil groups with different numbers of turns;

Figure 9B is a perspective view of four coil groups of the coil structure provided by the embodiment of the present invention;

Figure 10 is a top view of four coil groups of the coil structure provided by the embodiment of the present invention;

Figure 11 is a side view from the A1 direction in Figure 10;

Figure 12 is a side view from the A2 direction in Figure 10;

Figure 13 is a perspective view of sixteen coil groups of the coil structure provided by the embodiment of the present invention;

Figure 14 is a top view of sixteen coil groups of the coil structure provided by the embodiment of the present invention;

Figure 15 is a perspective view of two of the sixteen coil groups in Figure 13;

Figure 16 is a top view of two of the sixteen coil groups in Figure 13;

Figure 17 shows the sixteen coil groups and first connecting bars of the coil structure provided by the embodiment of the present invention. A top view of the second connecting strip;

Figure 18 is another top view of the sixteen coil groups and the first and second connecting bars of the coil structure provided by the embodiment of the present invention;

Figure 19 is a structural schematic diagram of the first coil unit and the second coil unit of the coil structure provided by the embodiment of the present invention;

Figure 20 is a structural schematic diagram of another coil structure provided by an embodiment of the present invention;

Figure 21 is yet another structural schematic diagram of another coil structure provided by an embodiment of the present invention;

FIG. 22 is a schematic structural diagram of a semiconductor process equipment provided by an embodiment of the present invention.

Detailed ways

In order 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 in the semiconductor process equipment provided by the present invention will be described in detail below with reference to the accompanying drawings.

This embodiment provides a coil structure for generating plasma in a semiconductor process equipment. The above-mentioned semiconductor process equipment can be used to perform an etching process on a wafer. The coil structure serves as an upper electrode to excite the process gas in the reaction chamber. Plasma is formed.

The coil structure includes M coil groups, where M is an integer greater than or equal to 4. Each coil group includes N layers of planar coils that are parallel to each other, and N is an even number greater than or equal to 4; The directions of the planes are set at intervals and connected end to end in series; the orthographic projection of each two adjacent layers of plane coils on the plane where the plane coils are located is mirror symmetrical. The so-called mirror image refers to the orthographic projection of one of the two adjacent layers of planar coils on the plane where the planar coil is located (hereinafter referred to as the first projection A) and the orthographic projection of the other layer of planar coils on the plane where the planar coil is located. The orthographic projection (hereinafter referred to as the second projection B) has the same shape, but the spiral direction is opposite. Specifically, the first projection A and the second projection B both have front and back sides parallel to the plane where the planar coil is located, and the first The front shape of one of the projections A and the second projection B is the same as the back shape of the other of the first projection A and the second projection B. The so-called symmetry refers to the positive direction of one of the first projection A and the second projection B. The face shape is identical to all parameters of the reverse face shape of the other one of the first projection A and the second projection B.

By making the two adjacent layers of planar coils in each coil group mirror symmetrical, the magnetic field and electric field generated by one of the planar coils and the other adjacent layer of planar coils can compensate each other, so that the coils can be compensated The difference in current distribution in the radial direction improves the radial distribution uniformity of the coupling energy generated under the coil, thereby improving the radial distribution uniformity of the free radical and ion density in the plasma and improving process uniformity.

As a comparative example of the embodiment of the present invention, please refer to FIG. 3A . The coil structure 03 is electrically connected to the radio frequency power supply 1 through the matching device 2 . The radio frequency power supply 1 is used to load radio frequency power to the coil structure 03 . The coil structure 03 includes a first coil unit 03a located in the outer circle and a second coil unit 03b located in the inner circle. The two coil units have the same structure but are different in size 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, which are spaced apart in the vertical direction and connected in series with each other; the first planar coil 031 and the second planar coil 032. The orthographic projection of the second planar coil 032 on the plane where the planar coil is located is mirror symmetrical. Although this can compensate for the difference in current distribution of the coil in the radial direction and improve the uniformity of the coupling energy generated under the coil in the radial direction, in order to avoid the interference of the current distribution between the first planar coil 031 and the second planar coil 032 The compensation effect of the difference fails, and the vertical distance 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 10 mm, the process uniformity is less than or equal to 1%), which makes the above-mentioned coil structure 03 The withstand voltage capability is low (less than or equal to 4kV), resulting in the maximum allowed feed power of the above-mentioned coil structure 03 being 2KW, which cannot be applied to high-power (more than 5KW) feed-in processes.

Please refer to Figure 3B, another coil structure 03', compared with the above-mentioned coil structure 03, the vertical spacing between the above-mentioned first planar coil 031 and the second planar coil 032 is increased to D2, and the vertical spacing D2 For example, it is 30mm. Although increasing the numerical spacing can increase the voltage resistance of the coil structure 03' to more than 12KV, it can be applied to high-power (more than 5KW) feed processes, but due to Excessive vertical spacing will cause the compensation effect of the current distribution difference between the first planar coil 031 and the second planar coil 032 to fail, and the process uniformity will deteriorate from 1% to 2.7%, which cannot meet the process uniformity requirements ( less than or equal to 1.5%).

In order to solve the above problem, please refer to Figure 4A. The coil structure 3 provided by 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; the coil unit is When there are multiple coil units, the coil groups in the multiple coil units have different sizes and are 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 in 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 practical applications, depending on specific needs, there may be only one coil unit, or there may be three or more coil units.

The structures of the first coil unit 3a and the second coil unit 3b are the same, but their sizes are different. Taking the first coil unit 3a as an example, it includes M coil groups. Each coil group includes N layers of planar coils that are parallel to each other. N is an even number greater than or equal to 4. Taking N=4 as an example, the 4-layer planar coils are given by 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; direction), and are connected in series end to end, that is, N layers of planar coils are connected in series; the orthographic projection of each two adjacent layers of planar coils on the plane where the planar coil is located is mirror symmetrical. It should be noted that FIG. 4A only schematically shows the planar coil using the “mouth” and does not represent the specific structure of the planar coil.

By including N layers of planar coils parallel to each other in the coil group, N is an even number greater than or equal to 4, that is, there are more than 4 layers of even-numbered planar coils in the coil group. This is compared to the coil structure 03 shown in Figure 3A above. , the vertical distance D5 between the input end and the output end of the coil group can be increased, that is, the distance between the uppermost first planar coil 31 and the lowermost fourth planar coil 34. The distance D5 is, for example, greater than or equal to 30mm, which can increase the voltage resistance 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 (more than 5KW) feed processes. At the same time, since the uppermost first planar coil 31 is provided below There is a second planar coil 32 adjacent to it. The orthographic projection of the second planar coil 32 and the first planar coil 31 on the plane where the planar coil is located is mirror symmetrical, that is, the shape is the same but the spiral direction is opposite. This can make The magnetic field and electric field generated by the two can compensate each other, that is, the magnetic field and the electric field generated by the second planar coil 32 are respectively superimposed with the magnetic field and electric field generated by the first planar coil 31 to form a total magnetic field and a total electric field distribution that is mirror symmetrical. , thereby being able to compensate for the difference in current distribution in the radial direction of the planar coils of each layer; similarly, a third planar coil 33 adjacent to the fourth planar coil 34 in the lowest layer is provided, and the third planar coil 33 and The orthographic projection of the fourth planar coil 34 on the plane where the planar coil is located is mirror symmetrical, so that the magnetic field and electric field generated by the two can compensate each other. In addition, the orthographic projections of the adjacent second planar coil 32 and the third planar coil 33 on the plane where the planar coils are located are mirror symmetrical, so that the magnetic fields and electric fields generated by the two can compensate each other. As a result, it is possible to compensate for the difference in current distribution of each layer of planar coils in the radial direction, improve the uniformity of the coupling energy generated under the coil in the radial direction, thereby increasing the radial density of free radicals and ions in the plasma. The distribution uniformity improves the process uniformity.

On this basis, an even number of planar coils with more than 4 layers are arranged at intervals in a direction perpendicular to the plane where the planar coils are located. Compared with the coil structure 03 in Figure 3A, the relationship between the input end and the output end of the coil group can be increased. (i.e., the distance between the uppermost planar coil and the lowermost planar coil) D5. The distance D5 increases to, for example, more than 30 mm. At the same time, the uppermost first planar coil 31 and the adjacent second planar coil 31 The distance between the coils 32 and the distance between the lowest fourth planar coil 34 and the adjacent third planar coil 33 are both D3. The distance between the adjacent second planar coil 32 and the third planar coil 33 is D3. The distance between them is D4, and the distances D3 and D4 are both less than or equal to 10mm, for example. This can ensure that the compensation effect of the adjacent two-layer planar coils on the difference in current distribution will not fail to ensure that the process uniformity meets the requirements. At the same time, since the total voltage applied by the RF power supply 1 to the input and output ends of the coil group through the matcher 2 is constant, the voltage withheld by each layer of planar coils is only 1/N of the total voltage, thereby improving the performance of the coil group. The overall voltage withstand capability enables high-power feed-in on the basis of meeting process uniformity requirements.

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

It should also be noted that the spacing between two adjacent layers of planar coils should not be too large to ensure that the compensation effect of each adjacent two layers of planar coils on the difference in current distribution will not fail, nor should it be too small to avoid each other. The distance between adjacent two-layer planar coils is too close, causing sparking. Optionally, the distance between each adjacent two layers of planar coils is less than or equal to 10 mm, such as 5 mm, 7 mm, etc.

In some optional embodiments, the shape of each layer of planar coils is a spiral involute.

In some optional embodiments, the height of each layer of planar coils in a direction perpendicular to the plane where the planar coils are located is greater than or equal to 2 mm and less than or equal to 15 mm.

In some optional embodiments, the number of turns of the planar coils in each layer can be set according to the required inductance. The greater the required inductance, the greater the number of turns. Specifically, the inductance and the number of turns are Proportional to the square of . Planar coils in different layers have the same number of turns. In addition, the number of turns of each layer of planar coils should not be too many, otherwise it will limit the number of coil groups (ie, the value of M) due to occupying more space in the circumferential direction. Preferably, N=4, and each layer of planar coils The number of turns of the coil is 0.25 turns. In this way, the total number of turns of the 4-layer planar coil is 1 turn, that is, it goes around once in the circumferential direction.

In a specific embodiment, please refer to FIG. 4B , taking the first coil unit 3a as an example, N=4, and the number of turns of each layer of planar coils is 2 turns. The four-layer planar coils are the first planar coil 31, the second planar coil 32, the third planar coil 33 and the fourth planar coil 34 from top to bottom; the four-layer planar coils are spaced apart in a direction perpendicular to the plane where the planar coils are located. , and are connected in series end to end. Specifically, each adjacent two layers of planar coils are connected in series through connecting posts 4 and are electrically conductive. The connecting posts 4 are, for example, arranged in a direction perpendicular to the plane where the planar coils are located. The input end 31a and the output end 31b of the coil group are respectively one end of the outer coil of the uppermost first planar coil 31 and the lowermost fourth planar coil 34. Each of the four-layer planar coils is a spiral involute with the same parameters, and the spiral directions of the adjacent two-layer planar coils are opposite. Specifically, on the plane perpendicular to the plane where the coil is located, from Viewed from a top view, the spiral direction of the first planar coil 31 is clockwise, while the spiral direction of the adjacent second planar coil 32 is counterclockwise, and the two are mirror symmetrical; The spiral direction of the three-planar coil 33 is clockwise, that is, the third planar coil 33 is mirror symmetrical to the second planar coil 32 and coincides with the first planar coil 31; the fourth planar coil 34 adjacent to the third planar coil 33 has The spiral direction is counterclockwise, that is, the fourth planar coil 34 is a mirror image of the third planar coil 33 and coincides with the second planar coil 32 .

In another specific embodiment, please refer to FIGS. 5 to 8 together. 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-layer planar coils are the first planar coil 31, the second planar coil 32, the third planar coil 33 and the fourth planar coil 34 from top to bottom; the four-layer planar coil is along the direction perpendicular to the plane where the planar coil is located (i.e. (Z direction in Figure 7) are spaced apart and connected in series end to end. Specifically, each adjacent two layers of planar coils are connected in series and electrically conductive through connecting posts 4. Orientation settings for the plane. The input end 31a and the output end 31b of the coil group are respectively the two ends where the uppermost first planar coil 31 and the lowermost fourth planar coil 34 are close to each other. Each of the four layers of planar coils is a spiral involute with the same parameters, and the spiral directions of the adjacent two layers of planar coils are opposite. Specifically, as shown in Figure 6, the first planar coil 31 and The second planar coil 32 is symmetrical with respect to the second axis O2 on a plane parallel to the plane coil (the spiral direction is opposite); the second planar coil 32 and the third planar coil 33 are symmetrical with respect to the first axis O2 on a plane parallel to the planar coil. The axis O1 is symmetrical (the spiral direction is opposite); the third planar coil 33 and the fourth planar coil 34 are symmetrical with respect to the second axis O2 on a plane parallel to the plane coil (the spiral direction is opposite).

As shown in Figure 8, the vertical spacing D5 between the input end 31a and the output end 31b of the coil group is equal to 2 times the spacing D3, the spacing D4, and the height H1 of the second planar coil 32 and the height H2 of the third planar coil 33. The sum of , that is, D5=2×D3+D4+H1+H2. For example, if the distance D3 and the distance D4 are both equal to 7mm, and the height H1 and the height H2 are both equal to 5mm, the distance D5 is 31mm, which can meet the process requirements for the voltage resistance of the coil structure.

For the coil structure shown in Figure 1, the orthographic shape on its radial section has asymmetry in the circumferential direction (ie, angular direction). Specifically, as shown in Figure 2B, the radial section It is divided into four quadrant areas (I, II, III, IV). Since the radius of the involute of each planar coil gradually increases as it extends from the inner end to the outer end, the coil structure is in the first quadrant. There are obvious differences between the parts in area I and the third quadrant area III and the parts in the second quadrant area II and the fourth quadrant area IV, which will lead to the current distribution of the above-mentioned coil structure in the circumferential direction (ie, angular direction) Differences are generated, resulting in uneven electromagnetic field distribution. During the process, it will cause asymmetry in the density distribution of free radicals and ions in the plasma, which will in turn cause uneven angular distribution of plasma density, ultimately affecting process uniformity.

In order to solve the above technical problems, the number of coil groups is designed to be M, and M is an integer greater than or equal to 4; the M coil groups have the same structure and are connected in parallel; the planar coils of each layer in the M coil groups correspond to each other one by one. They are arranged 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 evenly distributed. That is to say, 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, please refer to Figures 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. , each of the four coil groups includes N layers of planar coils that are parallel to each other (for example, N=4). Taking the four-layer planar coil shown in Figure 5 as an example, among the M coil groups, M first planes The coils 31 are arranged on the same layer, spaced apart from each other along the circumferential direction of the planar coil, and evenly distributed; M second planar coils 32 are arranged on the same layer, spaced apart from each other along the circumferential direction of the planar coil, and evenly distributed; M third plane coils The coils 33 are arranged on the same layer, spaced apart from each other along the circumferential direction of the planar coils, and evenly distributed; M fourth planar coils 34 are arranged on the same layer, spaced apart from each other along the circumferential direction of the planar coils, and evenly distributed. In other words, any coil group will overlap with another adjacent coil group after rotating a certain angle clockwise or counterclockwise along the circumferential direction of the planar coil. For example, four coil groups are shown in Figure 9B. In this case, taking the first coil group 3a1 as an example, after rotating 90° clockwise or counterclockwise along the circumferential direction of the planar coil, it will be connected to the adjacent coil group 3a1. Another coil group (for example, the second coil group 3a2 or the fourth coil group 3a4) overlaps. It is easy to understand that in the M coil groups, since the M planar coils arranged on the same layer are distributed on the same circumference, the first ends and the second ends of the M planar coils are respectively located on two concentric circles.

Since the M coil groups have the same shape and can be evenly distributed along the circumferential direction of the planar coil, the M planar coils corresponding to each layer of the M coil groups can jointly form an approximate circle in the circumferential direction of the planar coil. This allows the M coil groups to have angular symmetry in the circumferential direction of the planar coil, that is, symmetrical in the circumferential direction of the planar coil, thereby avoiding differences in current distribution in the circumferential direction, thereby improving plasma The angular distribution uniformity of density improves process uniformity.

It should be noted that if there are less than 4 coil groups, for example, Figure (a) in Figure 9A shows a coil group that has a two-layer planar coil structure, and Figure (b) in Figure 9A shows Two coil groups are constructed, each coil group has a two-layer planar coil structure. As can be seen from Figure (a), each layer in the coil group has only one planar coil, and the coil structure is in the circumferential direction of the planar coil (i.e. , is asymmetric in the angular direction, there will still be differences in current distribution; as can be seen from Figure (b), there are two planar coils in each layer of each coil group. Although the number of planar coils has increased, Since the two planar coils on the same layer are mirror symmetrical, the coil structure shown in Figure (b) is still asymmetrical in the circumferential direction (ie, angular direction) of the planar coil. The inventor found that only 4 or more coil groups (i.e., M≥4), and M planar coils located on the same layer arranged at different rotation angles in the circumferential direction, can form an approximate circle that satisfies The process requires angular uniformity. In addition, the more the number of the above-mentioned coil groups, that is, the larger the value of M, the better the angular uniformity. Preferably, M=4 or 8 or 16.

In some other optional embodiments, please refer to FIG. 13 and FIG. 14 together, M=16, and the 16 coil groups are the first coil group 3a1 to the sixteenth coil group 3a16 respectively. It should be noted that the greater 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 more conducive to improving the angular distribution symmetry of the plasma density. In some preferred embodiments , the number of coil groups (i.e., M value) is greater than or equal to 2 and less than or equal to 64.

In some optional embodiments, the M coil groups are connected in parallel to each other in the following manner: the input end and output end of each coil group (that is, the two ends where the uppermost planar coil and the bottommost planar coil are close to each other) are respectively The matching device 2 is electrically connected to the input terminal and the output terminal of the radio frequency power supply 1 . Optionally, in order to reduce the number of terminals of 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 set on the same layer (all located on the top or bottom layer), and in the circumferential direction of the planar coil Divided into M/2 input terminal groups (pairs of two), each input terminal group includes the input terminals of two adjacent coil groups, and the input terminals of the two adjacent coil groups are connected with the third An extension section is used to electrically connect the two; the first extension sections in the M/2 input terminal groups are electrically connected; similarly, the output terminals of the M coil groups are arranged on the same layer (all located at the bottom or the most upper layer), and is 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 the two adjacent coil groups A second extension section is connected between the output ends of each coil group to electrically connect the two; the second extension sections in the M/2 output end groups are electrically connected to each other.

Taking M=16 as an example, the input terminals of the 16 coil groups are arranged on the same layer and are divided into 8 input terminal groups in the circumferential direction of the planar coil. Each input terminal group includes the inputs of two adjacent coil groups. Terminal, Figure 15 and Figure 16 show the input terminals 31a of two adjacent coil groups (3a1, 3a2) of the sixteen coil groups, and the input terminals 31a of the two adjacent coil groups (3a1, 3a2). A first extension section 5a is connected therebetween for electrically connecting the two; and the first extension section 5a is electrically connected to another adjacent first extension section 5a. Similarly, Figures 15 and 16 show the output terminals 31b of two adjacent coil groups (3a1, 3a2) of the sixteen coil groups, and the output terminals of the two adjacent coil groups (3a1, 3a2). A second extension section 5b is connected between 31b to electrically connect the two; and the second extension section 5b is electrically connected to another adjacent second extension section 5b. As a result, 16 coil groups can be connected in parallel.

In some optional embodiments, as shown in Figure 15, the extension direction of the first extension section 5a is consistent with the extension direction of the planar coil connected to the first extension section 5a in one of the coil groups. For example, Figure In 15, the extension direction of the first extension section 5a is consistent with that of the planar coil connected to the first coil group 3a1 (for example, the uppermost planar coil); the extension direction of the second extension section 5b is consistent with that of one of the coil groups. The extension directions of the planar coils connected to the two extension sections 5b are consistent. For example, in FIG. 15, the extension directions of the second extension section 5b and the planar coils connected thereto (for example, the bottommost planar coil) of the second coil group 3a2 are consistent.

In some optional embodiments, as shown in Figure 15, a first terminal 51a for electrical connection with the output end of the radio frequency power supply 1 is provided at the middle position of the first extension section 5a; the middle position of the second extension section 5b is A second terminal 51b is provided for electrical connection with the input end of the radio frequency power supply 1. This ensures that the total length of the two adjacent coil groups is the same, so that the current flows through the two coil groups in the same path.

It should be noted that the M coil groups can be connected in parallel with each other in any other manner. For example, the input terminals of the M coil groups are directly electrically connected, and the output terminals of the M coil groups are directly electrically connected.

In some optional embodiments, in order to further reduce the number of terminals of the radio frequency power supply 1, the M/2 first terminals 51a are divided into M/4 first terminal groups (two by one) in the circumferential direction of the planar coil. Yes), as shown in Figure 17, each first terminal group includes two adjacent first terminals 51a, and a first connecting bar 6a is connected between the two adjacent first terminals 51a. To electrically connect the two; the middle position of the first connecting bar 6a is provided with an input terminal 61a for electrical connection with the output end of the radio frequency power supply 1; similarly, M/2 second terminals 51b are provided on the circumference of the planar coil Directionally divided into M/4 second terminal groups (two pairs), each second terminal group includes two adjacent second terminals 51b, and one of the two adjacent second terminals 51b A second connection bar 6b is connected between them for electrically connecting the two; an output terminal 61b for electrical connection with the input end of the radio frequency power supply 1 is provided at the middle position of the second connection bar 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. Terminal set.

In some optional embodiments, in order to ensure the symmetry of the coil structure in its circumferential direction, as shown in Figure 17, M/4 first connecting bars 6a are evenly distributed in the circumferential direction of the planar coil, M/4 The second connecting bars 6b are evenly distributed in the circumferential direction of the planar coil, and the diameter of the circle where the M/4 first connecting bars 6a are located is the same as the diameter of the circle where the M/4 second connecting bars 6b are located, and the M/4th One connecting bar 6a and M/4 second connecting bars 6b are staggered from each other in the circumferential direction of the planar coil, that is, they are arranged alternately in the circumferential direction of the planar coil. By staggering M/4 first connection bars 6a and M/4 second connection bars 6b in the circumferential direction of the planar coil, the line connection layout between the radio frequency power supply and the connection bars can be designed more conveniently. Of course, the embodiment of the present invention is not limited to this. For example, as shown in Figure 18, M/4 first connecting bars 6a and M/4 second connecting bars 6b can also be arranged in a direction perpendicular to the plane where the planar coil is located. The previous ones overlap each other in a one-to-one correspondence.

In some optional embodiments, the coil structure 3 includes multiple coil units, and the coil groups in the multiple coil units have different sizes and are nested with each other. For example, Figure 19 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 in each other. .

Optionally, the number of layers of the planar coils of the coil group in the first coil unit 3a is the same as the number of layers of the planar coils of the coil group in the second coil unit 3b, for example, both are four layers. However, the embodiment of the present invention is not limited to this. According to the power ratio of the first coil unit 3a and the second coil unit 3b, the number of plane coil layers of the coil group in the first coil unit 3a is different from that of the second coil unit 3b. The number of layers of planar coils in the coil group can also be different. Specifically, the greater the power fed in, the more layers there are; conversely, the smaller the power fed in, the fewer layers there are.

As another technical solution, this embodiment also provides a coil structure, which includes a first coil structure and a second coil structure nested in each other. Specifically, as shown in Figure 20, the first coil structure 201 and the second coil structure The structures 201 are all ring-shaped and have different sizes. The first coil structure 201 is located on the outer circle, and the second coil structure 202 is located on the inner circle; or, as shown in Figure 21, the second coil structure 202 is located on the outer circle, and the first coil structure is located on the outer circle. 201 is located in the inner circle.

Among them, the first coil structure 201 adopts the above-mentioned coil structure provided in this embodiment. The first coil structure 201 has a coil unit. The coil unit includes M coil groups, where M is an integer greater than or equal to 4, and each coil group has It includes N layers of planar coils that are parallel to each other. N is an even number greater than or equal to 4. The orthographic projection of each two adjacent layers of planar coils on the plane where the planar coil is located is mirror symmetrical. A 4-layer planar coil is schematically shown in Figures 20 and 21. By making the coil group include N layers of planar coils that are parallel to each other, N is an even number greater than or equal to 4, that is, there are more than 4 layers of even-numbered planar coils in the coil group, so that the top layer of planar coils can be aligned with the bottom layer of planar coils. The voltage resistance capacity between coils is increased to above 12KV, which can be applied to the process of feeding high power (more than 5KW) to the inner or outer ring.

The above-mentioned second coil structure 202 includes two layers of planar coils that are parallel to each other and connected in series end to end. The orthographic projection of the two layers of planar coils on the plane where the planar coils are located is mirror symmetrical. The two-layer planar coils in the second coil structure 202 are, for example, the first planar coil 031 and the second planar coil 032 shown in FIG. 3A . The above-mentioned second coil structure 202 can be applied to situations where the power fed into the outer coil or the inner coil is small (less than or equal to 2kW).

The coil structure provided by the embodiment of the present invention, by combining the above-mentioned coil structure provided by the embodiment of the present invention with two layers of planar coils that are parallel to each other and connected in series from end to end, can be applied to inner and outer rings with different feed power levels. situation, that is, the first coil structure 201 can be applied to high power feed (greater than 5kW), while the second coil structure 202 can be applied to low power feed (less than or equal to 2kW), thereby meeting a variety of different process requirements. .

As another technical solution, this embodiment also provides a semiconductor process equipment. For example, as shown in Figure 22, the semiconductor process equipment includes an upper electrode radio frequency power supply 1, a matching device 2, a reaction chamber 100, and a coil structure 3. Among them, a dielectric window 101 is provided on the top of the reaction chamber 100, and the coil structure 3 is provided above the dielectric window 101, and the coil structure 3 adopts the coil structure provided by the above-mentioned embodiments of the present invention, for example, the coil structure shown in Figure 4A 3.

The radio frequency power supply 1 is used to provide radio frequency power to the coil structure 3 through the matching device 2 to stimulate the reaction. The process gas in the chamber 100 forms plasma (Plasma). In addition, a base 102 is also provided in the reaction chamber 100 for carrying the wafer, and the base 102 is electrically connected to the radio frequency source 103 of the lower electrode. The radio frequency source 103 is used to load a radio frequency bias voltage to the base 102 to attract the plasma to move toward the wafer surface.

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 of the coil in the radial direction, but also improve the uniformity of the distribution of the coupling energy generated below the coil in the radial direction, thereby Improving the uniformity of the distribution of free radicals and ion density in the plasma in the radial direction can also improve the overall voltage resistance of the coil, thus enabling high-power feed.

It can be understood that the above embodiments are only exemplary embodiments adopted to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill 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 regarded as the protection scope of the present invention.

Claims

A coil structure for generating plasma in semiconductor process equipment, characterized in that the coil structure includes at least one coil unit, each of the coil units includes M coil groups, and 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 layers of planar coils parallel to each other, and N is an even number greater than or equal to 4; each layer of the M coil groups has The planar coils are arranged in the same layer in one-to-one correspondence, 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 evenly distributed;

The N layers of the planar coils in each coil group are spaced apart in a direction perpendicular to the plane where the planar coils are located, and are connected in series end to end; every two adjacent layers of the planar coils are arranged in a direction perpendicular to the plane where the planar coils are located. The orthographic projection on is mirror symmetrical.
The coil structure according to claim 1, wherein 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 are divided into M/2 input terminal groups in the circumferential direction of the planar coil. Each input terminal group includes two adjacent coils. The input terminals of the M/2 input terminal groups, and a first extension section is connected between the input terminals of two adjacent coil groups to electrically connect the two; the first extension section in the M/2 input terminal groups Electrical connection between extension sections;

The output ends of M coil groups are arranged on the same layer, and are divided into M/2 output end groups in the circumferential direction of the planar coil. Each of the output end groups includes two adjacent coils. The output terminals of the M/2 output terminal groups, and a second extension section is connected between the output terminals of two adjacent coil groups to electrically connect the two; the second extension section in the M/2 output terminal groups The extension sections are electrically connected.
The coil structure according to claim 2, wherein the extension direction of the first extension section is consistent with the extension direction of the planar coil connected to the first extension section in one of the coil groups;

The extension direction of the second extension section and one of the coil groups are related to the second extension section. The extension directions of the planar coils connected by segments are consistent.
The coil structure according to claim 2, characterized in that, a first terminal for electrical connection with the output end of the radio frequency power supply is provided in the middle position of the first extension section; and a first terminal is provided in the middle position of the second extension section. There is a second terminal for electrical connection with the input end of the radio frequency power supply.
The coil structure according to claim 4, wherein the M/2 first terminals are divided into M/4 first terminal groups in the circumferential direction of the planar coil, and each of the first terminal groups Each terminal group includes two adjacent first connection terminals, and a first connecting strip is connected between the two adjacent first connection terminals to electrically connect them; the first connection The middle position of the strip is provided with an input terminal for electrical connection with the output end of the radio frequency power supply;

The M/2 second terminals are divided into M/4 second terminal groups in the circumferential direction of the planar coil, and each of the second terminal groups includes two adjacent second terminals. terminals, and a second connection strip is connected between two adjacent second connection terminals for electrically connecting the two; the middle position of the second connection strip is provided with an input terminal for electrical connection with the radio frequency power supply. Connect the output terminals.
The coil structure according to claim 5, characterized in that, M/4 first connecting strips are evenly distributed in the circumferential direction of the planar coil, and M/4 second connecting strips are distributed in the plane. The coils are evenly distributed in the circumferential direction, and the diameter of the circle where the M/4 first connecting bars are located is the same as the diameter of the circle where the M/4 second connecting bars are located, and the M/4 first connecting bars are M/4 second connecting bars are staggered from each other in the circumferential direction of the planar coil.
The coil structure according to any one of claims 1 to 6, characterized in that the 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 there are a plurality of coil units, and the coil groups in the plurality of coil units have different sizes and are nested with each other. .
The coil structure according to claim 8, characterized in that there are two coil units, namely a first coil unit and a second coil unit, and the outer diameter of the second coil unit is smaller than that of the first coil unit. inner diameter;

The number of layers of the planar coils of the coil group in the first coil unit and the number of layers of the planar coils of the coil group in the second coil unit are set based on the power levels fed in by each. Certainly.
The coil structure according to any one of claims 1 to 6, characterized in that the distance between each two adjacent layers of the planar coils is less than or equal to 10 mm.
The coil structure according to any one of claims 1 to 6, characterized in that the number of the coil groups is greater than or equal to 4 and less than or equal to 64.
The coil structure according to any one of claims 1 to 6, wherein the height of the planar coil in a direction perpendicular to the plane of the planar coil is greater than or equal to 2 mm and less than or equal to 15 mm.
A coil structure, characterized by comprising a first coil structure and a second coil structure nested in each other, wherein the first coil structure adopts the coil structure according to any one of claims 1-12;

The second coil structure includes two layers of planar coils that are parallel to each other and connected in series end to end. The orthographic projections of the two layers of planar coils on the plane where the planar coils are located are mirror symmetrical.
A semiconductor process equipment, characterized by comprising a radio frequency source, a reaction chamber and the coil structure according to any one of claims 1-12, or the coil structure according to claim 13, wherein the top of the reaction chamber A dielectric window is provided, and the coil structure is arranged above the dielectric window; the radio frequency source is used to provide radio frequency power to the coil structure.