Lower electrode assembly, semiconductor process equipment and process method

Abstract

The invention provides a lower electrode assembly, semiconductor process equipment and a process method, and the lower electrode assembly comprises a bearing part which is used for bearing a wafer; the adjusting electrode is arranged in the bearing part, and the adjusting electrode comprises a plurality of sub-electrodes arranged in the same plane; the impedance adjusting device comprises a plurality of impedance adjusting units, all the impedance adjusting units and all the sub-electrodes are correspondingly arranged and electrically connected, and each sub-electrode and the corresponding impedance adjusting unit are used for being connected between a radio frequency power supply and the ground to form a radio frequency sub-loop; and the impedance adjusting unit is used for changing the impedance of the corresponding radio frequency sub-loop so as to change the current in the corresponding radio frequency sub-loop. According to the lower electrode assembly, the impedance adjusting units and the sub-electrodes are arranged, so that a plurality of radio frequency sub-loops which are connected in parallel can be formed, the process rate of each area is adjusted, the process rate of each area is consistent, and the uniformity of the process rate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor manufacturing, in particular, to a lower electrode assembly, a semiconductor process equipment and a process method. BACKGROUND

[0002] In a semiconductor process equipment, a plasma enhanced chemical vapor deposition (PECVD) is used for a dielectric film deposition process to grow a dielectric film mainly composed of Si, O and N on the surface of a wafer 100, and is also used for a doped film deposition process containing B and P.

[0003] With the development of semiconductor technology, the number of transistors on a wafer is increasing, and the processing precision of transistors on a wafer is also increasing, which requires higher and higher process. For example, in the prior art, due to the influence of the asymmetric structure in the chamber body, the process gas is not uniformly distributed, and the plasma density is also not uniform. The non-uniform plasma density will cause the deposited film to have an "eccentric" phenomenon, which affects the uniformity of deposition. In the prior art, to improve the "eccentric" phenomenon, usually, a radio frequency branch is added in parallel with the original radio frequency loop, and the current of the radio frequency branch is controlled to indirectly affect the original radio frequency loop

[0004] However, this method not only has a complex structure and is difficult to process, but also indirectly affects the radio frequency branch, so the capacitance needs to be repeatedly adjusted according to the process result to achieve the desired effect, which is complex and time-consuming. In addition, the additional radio frequency branch reduces the efficiency of radio frequency feeding, resulting in increased energy consumption. SUMMARY

[0005] The present application aims to at least solve the problem of the prior art that the way to improve the process uniformity is difficult to process and affects the efficiency of radio frequency feeding. A lower electrode assembly, a semiconductor process equipment and a process method are provided.

[0006] To achieve the purpose of the present application, a lower electrode assembly is provided for a semiconductor process equipment, the lower electrode assembly comprising: a bearing part for bearing a wafer; an adjusting electrode arranged in the bearing part, the adjusting electrode comprising: a plurality of sub-electrodes arranged in the same plane; an impedance adjusting device comprising: a plurality of impedance adjusting units, all the impedance adjusting units are arranged and electrically connected corresponding to all the sub-electrodes, each sub-electrode and the corresponding impedance adjusting unit are used to connect between a radio frequency power supply and the ground to form a radio frequency sub-loop; the impedance adjusting unit is used to change the impedance of the corresponding radio frequency sub-loop to change the current size in the corresponding radio frequency sub-loop.

[0007] Optionally, all the sub-electrodes are circumferentially spaced apart, each of the sub-electrodes is a fan-shaped, and all the sub-electrodes form the circular adjusting electrode.

[0008] Optionally, the impedance adjusting unit comprises: a current detection component for detecting the current in the radio frequency sub-circuit; and an impedance adjusting component connected in series with the corresponding sub-electrode and electrically connected with the corresponding current detection component, the impedance adjusting component being configured to change its impedance value according to the current in the radio frequency sub-circuit, so that the current in each radio frequency sub-circuit is consistent.

[0009] Optionally, the impedance adjusting device further comprises: a shielding shell having a first shielding cavity, all the impedance adjusting units being located in the first shielding cavity; and an insulating portion arranged in the first shielding cavity, each of the impedance adjusting components being connected with the insulating portion, and the impedance adjusting component being connected with the inner wall of the first shielding cavity through the insulating portion.

[0010] Optionally, the impedance adjusting device further comprises: a metal partition plate arranged in the shielding shell and separating the shielding shell into the first shielding cavity and a second shielding cavity; a plurality of driving portions each arranged in the second shielding cavity; and a plurality of transmission portions each arranged on the metal partition plate and corresponding to the driving portions, each of the driving portions being drivingly connected with one of the impedance adjusting components through the corresponding transmission portion, so as to adjust the impedance value of the corresponding impedance adjusting component.

[0011] According to the second aspect of the present application, a semiconductor process equipment is also disclosed, comprising: a chamber body; an upper electrode assembly; the above-mentioned lower electrode assembly, the carrier portion and the adjusting electrode being arranged in the chamber body, and the impedance adjusting device being arranged outside the chamber body.

[0012] Optionally, the chamber body has a transmission plate port and a pumping channel inlet inside, at least one sub-electrode being located close to the transmission plate port, and at least one sub-electrode being located close to the pumping channel inlet.

[0013] Optionally, the equipment further comprises: a controller electrically connected with the lower electrode assembly, configured to acquire the current value in the radio frequency sub-circuit and adjust the impedance value in the corresponding radio frequency sub-circuit according to the current value, so that the currents in each radio frequency sub-circuit are the same.

[0014] According to a third aspect of the present application, a process method for the semiconductor process equipment is also disclosed, comprising the steps of: obtaining current values of each of the RF sub-circuits, obtaining current preset values of the RF sub-circuits; comparing the current values with the current preset values, and selectively adjusting the impedance values of the impedance adjustment units of each of the RF sub-circuits according to the comparison results.

[0015] Optionally, the step of comparing the current values with the current preset values, and selectively adjusting the impedance values of the impedance adjustment units of each of the RF sub-circuits according to the comparison results comprises the steps of: if the current value of any of the RF sub-circuits is less than the current preset value, decreasing the impedance value of the corresponding RF sub-circuit; if the current value of any of the RF sub-circuits is greater than the current preset value, increasing the impedance value of the corresponding RF sub-circuit; and if the current value of any of the RF sub-circuits is equal to the current preset value, keeping the impedance value of the corresponding RF sub-circuit unchanged.

[0016] The lower electrode assembly of the present application can form multiple parallel RF sub-circuits by arranging multiple impedance adjustment units and multiple sub-electrodes, thereby adjusting the process rates of each region to make the process rates of each region consistent, and improving the uniformity of the process rates. Compared with the prior art, each impedance adjustment unit of the present application is electrically connected with a sub-electrode, and belongs to the arrangement of the sub-RF circuit, and does not need to arrange an additional RF branch, so that the power of the RF power supply will not be divided, and thus the process rate can be adjusted without changing the input power of the RF power supply, thereby effectively ensuring the feeding efficiency. Moreover, the adjusting electrode is divided into multiple sub-electrodes, and thus the structure is relatively simple, and a complex structure does not need to be added in the bearing part, and the modification cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Fig. 1 is a structural schematic diagram of a semiconductor process equipment in the related art;

[0018] Figure 2 Fig. 2 is a structural schematic diagram of a lower electrode assembly of an embodiment of the present application;

[0019] Figure 3 Fig. 3 is a structural schematic diagram of a semiconductor process equipment to which the lower electrode assembly of the embodiment of the present application is applied;

[0020] Figure 4 Fig. 4 is a structural schematic diagram of a sub-electrode of the lower electrode assembly of the embodiment of the present application;

[0021] Figure 5 Fig. 5 is an equivalent circuit schematic diagram of the semiconductor process equipment of the embodiment of the present application in a deposition process;

[0022] Figure 6 Process method step diagram of semiconductor process equipment of embodiment one of the present application;

[0023] List of reference signs:

[0024] 10, bearing part;

[0025] 20, adjusting electrode; 21, sub-electrode; 22, grounding copper column;

[0026] 30, impedance adjusting device; 31, impedance adjusting unit; 311, variable capacitor; 311A, first variable capacitor; 311B, second variable capacitor; 311C, third variable capacitor; 311D, fourth variable capacitor; 312, current detecting part; 312A, first current detecting part; 312B, second current detecting part; 312C, third current detecting part; 312D, fourth current detecting part; 313, connecting copper column; 32, shielding shell; 321, first shielding cavity; 322, second shielding cavity; 33, insulating part; 34, driving part; 35, metal partition plate;

[0027] 41, radio frequency sub-circuit; 41A, first radio frequency sub-circuit; 41B, second radio frequency sub-circuit; 41C, third radio frequency sub-circuit; 41D, fourth radio frequency sub-circuit;

[0028] 50, heating device;

[0029] 100, wafer; 210, chamber body; 211, mounting seat; 212, transmission port; 213, gas suction passage inlet; 220, upper electrode assembly; 221, power electrode; 230, radio frequency power supply; 240, matching device. DETAILED DESCRIPTION

[0030] In order to make the skilled in the art better understand the technical solutions of the present application, the lower electrode assembly, semiconductor process equipment and process method provided by the present application are described in detail below in combination with the drawings.

[0031] In the semiconductor process equipment, the plasma enhanced chemical vapor deposition equipment (PECVD) is used for the medium thin film deposition process, and is used for the doped thin film deposition process containing B and P, for growing the medium thin film mainly composed of Si, O and N on the wafer surface.

[0032] With the development of semiconductor technology, the number of transistors on a wafer is increasing, and the processing precision of transistors on a wafer is higher and higher, and the requirement for thin film deposition process is also higher and higher. The existing PECVD machine has a single deposition rate adjustment mode, which can only adjust the deposition rate by controlling the power input of the radio frequency, which leads to a single adjustment mode of the deposition rate and cannot meet the control requirements of the existing process.

[0033] As shown in Figure 1 A common PECVD machine includes a chamber body 1', an upper electrode assembly 2', and a liftable lower electrode assembly 3'. The upper electrode assembly 2' has a shower plate for uniformly spraying process gas into the inside of the chamber body 1', and the shower plate also serves as a CCP (Capacitive Coupled Plasma) power electrode 4' connected to a radio frequency feed column, responsible for feeding radio frequency power to excite plasma.

[0034] The liftable lower electrode assembly 3' includes a bearing part 5', a grounding electrode 6', and a heater 7'. The bearing part 5' has a bearing surface for bearing a wafer 8', the grounding electrode 6' and the heater 7' are both arranged in the bearing part 5', and the grounding electrode 6' is located between the heater 7' and the bearing surface. The heater 7' is used to heat the wafer 8' to the required temperature of the process. The liftable structure can be used to adjust the distance between the lower electrode assembly 3' and the upper electrode assembly 2' to achieve the best process effect. At the same time, the grounding electrode 6' and the power electrode 4' form a complete radio frequency loop. In the PECVD system, the grounding electrode 6' is a necessary component of the system, and the grounding electrode 6' is grounded through a copper metal column 9'.

[0035] In use, the radio frequency feed column feeds radio frequency power to the power electrode 4', and a strong high-frequency electric field is generated between the power electrode 4' and the grounding electrode 6' to excite plasma to achieve thin film deposition. In this process, the radio frequency current enters the grounding electrode 6' in turn after passing through the plasma, and then passes through the copper metal column 9' to form a complete radio frequency loop.

[0036] In the deposition process, the current in the radio frequency loop determines the density of the plasma, and the deposition rate is closely related to the plasma density. Therefore, the higher the current in the radio frequency loop, the higher the plasma density and the faster the deposition rate; the lower the current in the radio frequency loop, the lower the plasma density and the slower the deposition rate. In the prior art, if the current in the radio frequency loop is to be changed, the total power fed into the power electrode 4' needs to be changed. This adjustment method is too single, and the voltage and current of the radio frequency loop will change simultaneously, which cannot meet the increasingly complex process requirements.

[0037] In addition, due to the non-symmetrical structure of the transmission port 10' and the exhaust channel 11' provided in the chamber body 1', the uniformity of the electric field and the airflow field in the chamber body 1' is affected, which leads to uneven distribution of the process gas and uneven plasma density, and the uneven plasma density causes the deposited film to be "eccentric", affecting the uniformity of the deposition.

[0038] However, this method not only has a complex structure and difficult component processing, but also indirectly affects the RF branch by adjusting the capacitance according to the process results to achieve the desired effect, which is complicated and time-consuming. In addition, the additional RF branch reduces the efficiency of RF feeding, resulting in increased energy consumption.

[0039] To solve the above problems, as shown in Figure 2 An embodiment of the present application discloses a lower electrode assembly for a semiconductor process equipment, such as a chemical vapor deposition equipment, an ICP inductively coupled plasma deposition equipment, or as a CCP capacitively coupled plasma deposition equipment, an etching equipment.

[0040] As shown in Figure 2 The lower electrode assembly includes a bearing part 10, an adjusting electrode 20, and an impedance adjusting device 30. The bearing part 10 is used to bear a wafer 100, and the adjusting electrode 20 is arranged in the bearing part 10.

[0041] The adjusting electrode 20 includes a plurality of sub-electrodes 21 arranged in the same plane, each of which is used to be coupled with a power electrode 221, and all of the sub-electrodes 21 are coupled with the adjusting electrode 20 respectively.

[0042] The impedance adjusting device 30 includes a plurality of impedance adjusting units 31, all of which are arranged and electrically connected with all of the sub-electrodes 21, each of which is arranged in series with the corresponding impedance adjusting unit 31, and each of the sub-electrodes 21 and the corresponding impedance adjusting unit 31 is used to be connected between the RF power supply 230 and the ground to form an RF sub-circuit 41, and the impedance adjusting unit 31 is used to change the impedance of the corresponding RF sub-circuit 41, so that the current size in the corresponding RF sub-circuit 41 is changed to adjust the deposition rate of the corresponding area of each sub-electrode 21.

[0043] The lower electrode assembly of the present application forms a complete RF loop during the process, in which the RF current emitted by the RF power source 230 flows back to the RF power source 230 through the power electrode 221, the plasma, the adjusting electrode 20 and the impedance adjusting unit 31 in sequence. In this way, the adjusting electrode 20 is divided into multiple sub-electrodes 21, and each of the multiple sub-electrodes 21 can be coupled with the power electrode 221 individually, thereby forming multiple parallel RF sub-loops 41, and each of the multiple parallel RF sub-loops 41 is provided with an impedance adjusting unit 31, and the impedance of the RF sub-loop 41 can be adjusted by the impedance adjusting unit 31, thereby realizing the independent adjustment of the current in the RF sub-loop 41. By adjusting the current in the RF sub-loop 41, the plasma density in the area corresponding to each sub-electrode 21 can be changed, thereby realizing the independent adjustment of the deposition rate in different areas.

[0044] The lower electrode assembly of the present application forms multiple parallel RF sub-loops 41 by providing multiple impedance adjusting units 31 and multiple sub-electrodes 21, thereby adjusting the process rate in each area to make the process rates in each area consistent, thereby improving the uniformity of the process rate. Compared with the prior art, each impedance adjusting unit 31 of the present application is electrically connected with the sub-electrode 21, and belongs to the sub-RF loop 41, and does not need to be provided with an additional RF branch, so the power of the RF power source 230 will not be divided, and therefore the input power of the RF power source 230 can be adjusted without changing the input power, thereby effectively ensuring the feeding efficiency. Moreover, the adjusting electrode 20 is divided into multiple sub-electrodes 21, and therefore the structure is relatively simple, and the complex structure does not need to be added in the carrier 10, and the modification cost is low.

[0045] It should be noted that in the present embodiment, the process rate can be the deposition rate or the etching rate, etc. When the lower electrode assembly is used in a semiconductor deposition device, the deposition rate can be adjusted to ensure the uniformity of the deposition rate, and when it is used in a semiconductor etching device, the etching rate can be adjusted to ensure the uniformity of the etching rate.

[0046] In addition, since each sub-electrode 21 in the adjusting electrode 20 is arranged inside the carrier 10 and does not contact the plasma, only the carrier 10 can contact the plasma, and the carrier 10 is made of ceramic material, which is very stable in chemical properties and is difficult to react with the active substances of the plasma, thereby effectively reducing the generation of reaction by-products and avoiding the generation of particles, and improving the quality of the wafer 100.

[0047] It should be noted that in the present embodiment, the sub-electrode 21 is grounded through the impedance adjusting unit 31, but this is not restrictive, and in some other embodiments not shown in the figure, the impedance adjusting unit 31 can also be connected to the radio frequency power supply 230, as long as the radio frequency sub-circuit 41 current regulation can be realized through the impedance adjusting unit, which is within the protection scope of the present application.

[0048] It should also be noted that in use, the bearing part 10 is arranged inside the chamber body 210 of the semiconductor process equipment and fixedly connected with the mounting seat 211, while the impedance adjusting device 30 is arranged outside the chamber body 210 and connected at the bottom of the mounting seat 211, and the adjusting electrode 20 is electrically connected with the impedance adjusting unit 31 through the grounding copper column 22.

[0049] The impedance adjusting unit 31 comprises an impedance adjusting part 311, a connecting copper column 313 and a current detection component 312. One end of the impedance adjusting part 311 is connected in series with the corresponding sub-electrode 21, and the other end of the impedance adjusting part 311 is electrically connected with the connecting copper column 313 and grounded through the connecting copper column 313. The current detection component 312 is electrically connected with the corresponding impedance adjusting part 311 and is used for detecting the current size of the radio frequency sub-circuit 41. The impedance adjusting part 311 changes its impedance value according to the current size in the radio frequency sub-circuit 41, so as to make the impedance sizes of the respective radio frequency sub-circuits 41 consistent, thereby making the current sizes in the respective radio frequency sub-circuits 41 consistent and improving the process uniformity.

[0050] It should be noted that in the present embodiment, the impedance adjusting part 311 is a variable capacitor, but this is not restrictive, and in some other embodiments not shown in the figure, the impedance adjusting part 311 can also adopt a variable inductor or other components that can change the impedance value. In the following, the structure of the impedance adjusting device 30 will be specifically described by taking the impedance adjusting part 311 as a variable capacitor as an example:

[0051] As shown in Figure 2 The impedance adjusting device 30 further comprises a shielding shell 32 and an insulation part 33. The shielding shell 32 is connected with the mounting seat 211 at the top, and the shielding shell 32 has a first shielding cavity 321, and the impedance adjusting part 311 is located in the first shielding cavity 321. The insulation part 33 is arranged in the first shielding cavity 321 and connected with the impedance adjusting part 311, and the impedance adjusting part 311 is connected with the inner wall of the first shielding cavity 321 through the insulation part 33. By arranging the insulation part 33, the impedance adjusting part 311 is fixedly connected with the inner wall of the first shielding cavity 321 through the insulation part 33, so as to fix the impedance adjusting part 311 with the shielding shell 32 while maintaining insulation.

[0052] It should be noted that the insulation part 33 can be one larger insulation part 33, and the plurality of impedance adjusting members 311 are arranged on the insulation part 33, or the insulation part 33 can be a plurality of smaller insulation parts 33, and each impedance adjusting member 311 is fixedly connected to the inner wall of the first shielding cavity 321 through one insulation part 33. In this embodiment, the insulation part 33 is a plurality of insulation parts 33, and each insulation part 33 is connected to one impedance adjusting member 311.

[0053] The impedance adjusting device 30 further comprises a plurality of driving parts 34 and a plurality of transmission parts (not shown in the figure). All the driving parts 34 are arranged outside the first shielding cavity 321, so as to prevent interference of the radio frequency signals; all the transmission parts are arranged on the inner wall of the first shielding cavity 321 and are arranged in one-to-one correspondence with the driving parts 34, and each driving part 34 is drivingly connected to one impedance adjusting member 311 through the corresponding transmission part, so as to adjust the capacitance value of the corresponding impedance adjusting member 311.

[0054] The impedance adjusting device 30 further comprises a metal partition plate 35 arranged in the shielding shell 32 and separating the inside of the shielding shell 32 into the first shielding cavity 321 and the second shielding cavity 322, and the driving parts 34 are arranged in the second shielding cavity 322. All the insulation parts 33 are connected to the metal partition plate 35 and arranged in one-to-one correspondence with the driving parts 34; the inside of the insulation part 33 is provided with a driving channel, one end of each transmission part is located in the driving channel of the corresponding insulation part 33 and drivingly connected to the corresponding impedance adjusting member 311, and the other end is arranged on the metal partition plate 35 and drivingly connected to the corresponding driving part 34. In use, each driving part 34 (for example, a motor) drives the capacitance value of the corresponding impedance adjusting member 311 to change through the corresponding transmission part (for example, a transmission shaft or a transmission rod), so as to realize current adjustment of the corresponding radio frequency sub-circuit 41. By arranging the first shielding cavity 321 and the second shielding cavity 322, most of the radio frequency signals are shielded in the first shielding cavity 321, so that the radio frequency signals in the second shielding cavity 322 are very few, and the influence of the radio frequency signals on the driving part 34 can be basically avoided. In addition, the second shielding cavity 322 can further shield the radio frequency signals leaked from the first shielding cavity 321, so as to avoid leakage of the radio frequency signals. Moreover, by arranging the driving channel in the inside of the insulation part 33, the assembly space can be effectively saved, and the space utilization rate is improved.

[0055] The structure and working principle of the lower electrode assembly of the first embodiment will be described in detail below in combination with a specific semiconductor process equipment, as shown in FIG. 1, in this embodiment, the semiconductor process equipment is a chemical vapor deposition equipment. Figure 3

[0056] As shown in FIG. 1, the lower electrode assembly of the first embodiment comprises a shielding shell 32, a plurality of impedance adjusting members 311, a plurality of insulation parts 33, and a plurality of driving parts 34. Figure 3 ​As shown, the semiconductor process equipment includes: a chamber body 210, an upper electrode assembly 220, a radio frequency power supply 230, a matcher 240 and the above-mentioned lower electrode assembly. The upper electrode assembly 220 has a power electrode 221, and the radio frequency power supply 230 is electrically connected with the power electrode 221 through the matcher 240. The lower electrode assembly includes: a bearing part 10, an adjusting electrode 20 and an impedance adjusting device 30. The bearing part 10 is a susceptor, which has a bearing surface for bearing a wafer 100, and is arranged in the chamber body 210. The adjusting electrode 20 is arranged in the bearing part 10. The impedance adjusting device 30 is arranged outside the chamber body 210, and the adjusting electrode 20 is electrically connected with the impedance adjusting device 30 through a grounding copper column 22.

[0057] It should be noted that the number of sub-electrodes 21 can be two, three, four or more, and the more the number of sub-electrodes 21, the higher the adjusting ability for uniformity. The number of sub-electrodes 21 can be set according to actual needs. In this embodiment, the number of sub-electrodes 21 is four, and the number of corresponding grounding copper columns 22, radio frequency sub-circuits 41 and impedance adjusting units 31 is also four.

[0058] The semiconductor process equipment further includes: a controller, which is electrically connected with the lower electrode assembly, is used for acquiring a current value in the radio frequency sub-circuit 41, and adjusts the impedance value in the corresponding radio frequency sub-circuit 41 according to the current value, so that the currents in the radio frequency sub-circuits 41 are the same.

[0059] All the sub-electrodes 21 are circumferentially spaced, each sub-electrode 21 is a fan shape, and all the sub-electrodes 21 form a circular adjusting electrode 20. In this embodiment, as shown in Figure 4 , the four sub-electrodes 21 are fan shapes with the same size and shape, each fan shape has a central angle of 90°, and the four sub-electrodes 21 are circumferentially spaced to form a circular adjusting electrode 20. In order to ensure the consistency of the initial capacitance, all the sub-electrodes 21 are located in the same plane.

[0060] As shown in Figure 3 , among the four sub-electrodes 21, one sub-electrode 21 is located near the wafer transfer port 212 of the chamber body 210, and one sub-electrode 21 is located near the inlet 213 of the exhaust channel. Each sub-electrode 21 is spaced apart, and the spacing distance is 1 mm. The gap is filled with ceramic material to isolate the adjacent sub-electrodes 21 and form independent radio frequency sub-circuits 41. By arranging one sub-electrode 21 near the wafer transfer port 212 and near the inlet 213 of the exhaust channel, the process rate of the corresponding area can be adjusted to reduce the influence of the asymmetric structures such as the wafer transfer port 212 and the exhaust channel on the uniformity of the electric field and the gas flow field, thereby improving the uniformity of the process.

[0061] It can be understood that the gap between the sub-electrodes 21 needs to be as small as possible to ensure that the middle ceramic material is not broken down by the high voltage between the sub-electrodes 21. If the gap is too large, it will affect the deposition rate of the film layer directly above the gap, resulting in poor film layer uniformity. The gap can be filled with a non-conductive ceramic material, such as aluminum nitride ceramic material, which has a direct current breakdown voltage of 15KV / mm and a radio frequency breakdown voltage of 3.75KV / mm. In general, the power of the radio frequency power supply 230 used is usually not more than 1500W, and under this power condition, the maximum voltage difference between the sub-electrodes 21 is about 2.5KV. Considering a certain safety margin, the gap here is set to 1mm (withstanding voltage value of 3.5KV). In addition, each sub-electrode 21 is connected to a ground copper column 22, and through the corresponding adjustable capacitor, the ground copper column 22 is in an atmospheric environment, and the atmospheric radio frequency breakdown voltage is 300V / mm. The ground copper column 22 and the sub-electrode 21 are essentially at the same potential, so it is also necessary to avoid breakdown. Therefore, the spacing between the ground copper columns 22 should be greater than 8.3mm. Considering the safety margin and avoiding excessive space occupation, the ground copper column 22 is arranged at a distance of 10mm from the center axis of the adjusting electrode 10 of the bearing seat 10.

[0062] In order to better describe the working principle of the present embodiment, the equivalent circuit in the deposition process is shown in Figure 5 The radio frequency power supply 230 generates plasma between the power electrode 221 and the four sub-electrodes 21 and forms four radio frequency sub-circuits 41, namely first radio frequency sub-circuit 41A, second radio frequency sub-circuit 41B, third radio frequency sub-circuit 41C and fourth radio frequency sub-circuit 41D.

[0063] Among them, the plasma itself is equivalent to a resistor R pA ~R pD , the upper and lower sheath layers are equivalent to a capacitor C 上鞘层A ~C 上鞘层D and C 下鞘层A ~C 下鞘层D . Since the sub-electrodes 21 in the lower electrode assembly are located inside the bearing part 10, there is a ceramic layer between the wafer 100 placed on the bearing surface and the sub-electrode 21. Here, the wafer 100 and the ceramic layer below the lower sheath layer are equivalent to a capacitor C 陶瓷层A～D , the four ground copper columns 22 are equivalent to an inductor L 接地铜柱A ~L 接地铜柱D , the four impedance adjusting members 311 are first variable capacitor 311A, second variable capacitor 311B, third variable capacitor 311C and fourth variable capacitor 311D, and the four current detecting members 312 are first current detecting member 312A, second current detecting member 312B, third current detecting member 312C and fourth current detecting member 312D.

[0064] AsFigure 5 As shown, after the RF power source 230 outputs power, the RF current first flows into the matching device 240 through the coaxial cable, and then flows into the power electrode 221 through the feed post connected to the output end of the matching device 240. The plasma is generated between the power electrode 221 and the four sub-electrodes 21 below the power electrode 221, and thus the rear of the power electrode 221 can be equivalent to four parallel RF sub-circuits 41. The total voltage of each RF sub-circuit 41 is equal, and the impedance of the RF sub-circuit 41 can be changed by adjusting the capacitance of the impedance adjusting element 311 on the RF sub-circuit 41, so as to affect the current on the RF sub-circuit 41. The current on each RF sub-circuit 41 affects the plasma density on the RF sub-circuit 41, and further affects the deposition rate at the corresponding position.

[0065] Taking the first RF sub-circuit 41A as an example, in the first RF sub-circuit 41A, the total capacitive reactance is Z C and the total impedance Z L is:

[0066] Z C = -j x 1 / 2πfC Formula One

[0067] Z L = j2πfL Formula Two

[0068] In Formula One and Formula Two, j is a constant, C is the total capacitance of all capacitors in the first RF sub-circuit 41A, L is the total inductance of all inductors in the first RF sub-circuit 41A, and f is the RF frequency of the RF power source 230.

[0069] In the first RF sub-circuit 41A, the total total impedance Z A of all capacitors is the sum of the impedances of the equivalent capacitors and inductors in the equivalent circuit, that is, Z A = Z L + Z C . Assuming that the voltage on the power electrode 221 is V, the current I A on the first RF sub-circuit 41A is:

[0070] I A = V / Z A Formula Three

[0071] In Formula Three, I A is closely related to the plasma density of the first RF sub-circuit 41A, and I AThe greater the current, the greater the number of charged particles in the plasma of the first radio frequency sub-circuit 41A, that is, the higher the plasma density. During thin film deposition, the rate of thin film generation is mainly affected by the density of active substance ions. By changing the value of the first variable capacitor 311A in the first radio frequency sub-circuit 41A, the impedance of the first radio frequency sub-circuit 41A as a whole can be changed, thereby changing the current of the first radio frequency sub-circuit 41A, adjusting the plasma density above the corresponding sub-electrode 21, and accordingly, the deposition rate above the sub-electrode 21 also changes: the greater the current, the higher the plasma density, and the faster the deposition rate; the smaller the current, the lower the plasma density, and the slower the deposition rate.

[0072] During the process, due to some asymmetric structures in the chamber body 210, the electric field flow field distribution in the chamber is affected, and then the plasma density distribution is affected, causing the deposition rate at some positions to be different from that at other positions, which is commonly known as the "eccentric" phenomenon. In the present embodiment, the current on the sub-electrode 21 below the position with abnormal rate is different from the current at other positions. At this time, the control system adjusts the impedance adjusting unit 311 of the radio frequency sub-circuit 41 according to the value detected by the current detection component 312, so that the currents of the radio frequency sub-circuits 41 are equal, and the plasma densities above the radio frequency sub-circuits 41 are the same, and the deposition rates are equal.

[0073] In the present embodiment, the semiconductor process equipment further comprises a heating device 50, which is arranged in the bearing part 10, and the adjusting electrode 20 is located between the heating device 50 and the bearing surface of the bearing part 10. In the present embodiment, the heating device comprises a heating wire.

[0074] As Figure 6 shown, according to another aspect of the present application, a process method for the above-mentioned semiconductor process equipment is also disclosed, comprising the following steps:

[0075] obtaining the current value I1 of each radio frequency sub-circuit 41, and obtaining the current preset value I0 of the radio frequency sub-circuit 41;

[0076] comparing the current value I1 and the current preset value I0, and selectively adjusting the impedance value of the impedance adjusting unit 31 of each radio frequency sub-circuit 41 according to the comparison result.

[0077] The current value I1 of each radio frequency sub-circuit 41 represents the deposition rate of the region corresponding to the sub-electrode 21 on the radio frequency sub-circuit 41, the greater the value of I1, the greater the deposition rate, and the smaller the value of I1, the smaller the deposition rate, so by obtaining the current value I1 of each radio frequency sub-circuit 41, the deposition rate of different regions can be determined according to the current value I1 of each radio frequency sub-circuit 41. By setting the current preset value I0 of the radio frequency sub-circuit 41, a judgment standard can be established to unify the current value, and then the deposition rate can be adjusted to be consistent.

[0078] Specifically, comparing the current value I1 and the current preset value I0, and selectively adjusting the impedance value of the impedance adjusting unit of each radio frequency sub-circuit 41 according to the comparison result includes the following steps:

[0079] If the current value I1 in any radio frequency sub-circuit 41 is less than the current preset value I0, the impedance value in the corresponding radio frequency sub-circuit 41 is controlled to decrease; that is, if I1

[0080] If the current value I1 in any radio frequency sub-circuit 41 is greater than the current preset value I0, the impedance value in the corresponding radio frequency sub-circuit 41 is controlled to increase; that is, if I1

[0081] If the current value I1 in any radio frequency sub-circuit 41 is equal to the current preset value I0, the impedance value in the corresponding radio frequency sub-circuit 41 is kept unchanged. That is, if I1

[0082] The following will be described in detail Figure 5 The way of increasing / decreasing the deposition rate of the present application will be described in detail:

[0083] In this embodiment, since the inductance of the ground copper pillar 22 is positive impedance and the impedance adjusting member 311 is negative impedance, the impedance adjusting member 311 can offset a part of the inductance of the ground copper pillar 22, so that the impedance adjusting member 311 can reduce the impedance of the radio frequency sub-circuit 41 in which it is located within a certain range, increase the current, and increase the deposition rate. Taking the first radio frequency sub-circuit 41A as an example, Z C1 represents the impedance of the first variable capacitor 311A, that is:

[0084] When |Z C1 +Z L接地铜柱A |<Z L接地铜柱A , that is, the total impedance is reduced compared with the case without the first variable capacitor 311A, the total current is increased, the plasma density is increased, and thus the deposition rate is increased;

[0085] When |Z C1 +Z L接地铜柱A |>Z L接地铜柱A , that is, the total impedance is reduced compared with the case without the first variable capacitor 311A, the total current is reduced, the plasma density is reduced, and thus the deposition rate is reduced;

[0086] When |Z C1 +Z L接地铜柱A |=0, at this time, the total impedance is 0, the current is maximum, the plasma density is maximum, and thus the deposition rate is maximum.

[0087] Before the deposition process is performed, the values of the impedance adjusting members 311 in the respective RF sub-circuits 41 are adjusted to be the same, and then the deposition process is started. During the deposition process, the current values are detected by the current detecting members 312 in the respective RF sub-circuits 41. If the current values of all the RF sub-circuits 41 are equal to the preset value I0, it is indicated that the deposition rate is uniform. If the current values of the respective RF sub-circuits 41 are not the same, it is indicated that the deposition rate is not uniform. The impedance adjusting members 311 can be adjusted so that the current values in the respective RF sub-circuits 41 are equal to I0, thereby making the deposition rate in each region uniform.

[0088] It can be understood that the above embodiments are only exemplary embodiments for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of the present application, and these modifications and improvements are also considered to be within the protection scope of the present application.

Claims

1. A lower electrode assembly for a semiconductor process apparatus, characterized by, The lower electrode assembly comprises: a bearing part for bearing a wafer; a regulating electrode arranged in the bearing part, the regulating electrode comprising a plurality of sub-electrodes arranged in the same plane; an impedance adjusting device comprising a plurality of impedance adjusting units, all of the impedance adjusting units being arranged and electrically connected with all of the sub-electrodes, each of the sub-electrodes and the corresponding impedance adjusting unit being used for connecting between a radio frequency power source and ground to form a radio frequency sub-loop; the impedance adjusting unit is used for changing the impedance of the corresponding radio frequency sub-loop to change the current size in the corresponding radio frequency sub-loop.

2. The lower electrode assembly according to claim 1, wherein all of the sub-electrodes are distributed in a circumferential direction, each of the sub-electrodes is a fan-shaped, and all of the sub-electrodes form a circular regulating electrode.

3. The lower electrode assembly of claim 1, wherein, the impedance adjusting unit comprises: a current detection component for detecting the current in the radio frequency sub-loop; an impedance adjusting member connected in series with the corresponding sub-electrode and electrically connected with the corresponding current detection component, the impedance adjusting member being used for changing its impedance value according to the current size in the radio frequency sub-loop to make the current size in each radio frequency sub-loop consistent.

4. The lower electrode assembly of claim 3, wherein, the impedance adjusting device further comprises: a shielding shell having a first shielding cavity, all of the impedance adjusting units being located in the first shielding cavity; an insulating part arranged in the first shielding cavity, each of the impedance adjusting members being connected with the insulating part, and the impedance adjusting member being connected with the inner wall of the first shielding cavity through the insulating part.

5. The lower electrode assembly of claim 4, wherein, the impedance adjusting device further comprises: a metal partition plate arranged in the shielding shell and separating the shielding shell into the first shielding cavity and a second shielding cavity, a plurality of driving parts each arranged in the second shielding cavity; a plurality of transmission parts each penetrating the metal partition plate and arranged in one-to-one correspondence with the driving parts, each of the driving parts being drivingly connected with one of the impedance adjusting members through the corresponding transmission part to adjust the impedance value of the corresponding impedance adjusting member.

6. A semiconductor process apparatus characterized by comprising: comprises: a chamber body; an upper electrode assembly; the lower electrode assembly according to any one of claims 1 to 5, the bearing part and the regulating electrode being arranged in the chamber body, and the impedance adjusting device being arranged outside the chamber body.

7. The semiconductor process equipment according to claim 6, wherein the chamber body has a wafer transfer port and a pumping channel inlet inside, at least one sub-electrode is located close to the wafer transfer port, and at least one sub-electrode is located close to the pumping channel inlet.

8. The semiconductor process apparatus according to claim 7, wherein further comprising: a controller electrically connected with the lower electrode assembly, used for acquiring the current value in the radio frequency sub-loop and adjusting the impedance value in the corresponding radio frequency sub-loop according to the current value, so that the currents in each of the radio frequency sub-loops are the same.

9. Process method for a semiconductor process apparatus according to any one of claims 6 to 8, characterized in that comprising the following steps: acquiring the current value of each radio frequency sub-loop and acquiring the preset current value of the radio frequency sub-loop; comparing the current value and the preset current value, and selectively adjusting the impedance value of the impedance adjusting unit of each radio frequency sub-loop according to the comparison result.

10. The process of claim 9, wherein, The comparison of the current value and the current preset value, and the selective adjustment of the impedance value of the impedance adjustment unit of each of the radio frequency sub-circuits according to the comparison result comprises the following steps: If the current value in any of the radio frequency sub-circuits is less than the current preset value, the impedance value in the corresponding radio frequency sub-circuit is controlled to decrease; If the current value in any of the radio frequency sub-circuits is greater than the current preset value, the impedance value in the corresponding radio frequency sub-circuit is controlled to increase; If the current value in any of the radio frequency sub-circuits is equal to the current preset value, the impedance value in the corresponding radio frequency sub-circuit is kept unchanged.

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