Method for cleaning cavity using remote plasma and modulated direct plasma

Abstract

The present invention relates to a method for cleaning a cavity, comprising the steps of: generating a remote plasma source (RPS) plasma in a remote plasma source (RPS); supplying radicals from the RPS plasma into the chamber; generating a direct plasma (Direct Plasma) in an in-situ (in-situ) manner within the cavity; and adjusting the form of the direct plasma through impedance tuning at the lower part of the cavity. According to an embodiment of the present invention, ex-situ cleaning using remote plasma and in-situ cleaning using modulated direct plasma are simultaneously applied, thereby significantly improving cleaning efficiency.

Description

Technical Field

[0001] The present invention relates to a cavity cleaning method, and more particularly, to a cavity cleaning method for a semiconductor device manufacturing process, which simultaneously applies ex-situ cleaning using remote plasma and in-situ cleaning using modulated direct plasma, thereby significantly improving the cleaning efficiency. Background Art

[0002] In the semiconductor device manufacturing process, the substrate may be etched, deposited or otherwise processed. For example, in a substrate processing system, various deposition processes, etching processes or other processes such as atomic layer deposition (ALD), plasma enhanced atomic layer deposition (PEALD), chemical vapor deposition (CVD), and plasma enhanced chemical vapor deposition (PECVD) for forming a thin film on a substrate are performed, and a radio frequency (RF) electric field is usually applied in the process chamber to form a plasma.

[0003] As described above, in a manufacturing process using plasma, in addition to the thin film forming substances used in the process, byproducts such as polymers may also adhere to and accumulate on the wall, substrate support or other components inside the process chamber. Afterwards, the accumulated substances will peel off from the attached parts, float in the above-mentioned process chamber, and then adhere to the substrate as foreign matter, thereby becoming a particle factor causing process defects. In addition, process byproducts may produce unexpected negative results in subsequent processes.

[0004] Therefore, in order to prevent the above problems, a cleaning process is performed on the process chamber as a regular maintenance operation. The cleaning process can be performed by in-situ plasma cleaning using direct plasma, and the direct plasma is formed using an active gas. In the in-situ plasma cleaning, a cleaning gas is flowed into the chamber, and a high-frequency power is applied in a direct RF manner to excite the cleaning gas into a plasma state, thereby generating active species. Through the reaction between the active species and the deposits, the reactants are released to the outside of the chamber in the form of gaseous substances, thereby removing them.

[0005] However, in the above-mentioned direct plasma method, the high-frequency power applied to the above-mentioned cleaning gas will generate a large ion impact between the electrodes, resulting in plasma damage such as damage to the electrode surface and shedding of the surface layer. In addition, if the high-frequency power is increased in order to improve the cleaning efficiency, it is easy to achieve plasma, thereby increasing the physical collision energy of the particles forming the plasma, which will not only produce by-products deposited on the inner wall of the above-mentioned cavity, but also cause damage to the walls or components constituting the above-mentioned cavity. As a result, the life of the components may be shortened and the process efficiency may be reduced. In addition, if the high-frequency power is reduced in order to prevent the occurrence of the above-mentioned situation, the formation of active species will be insufficient, thereby reducing the cleaning efficiency of the inside of the above-mentioned cavity.

[0006] In order to deal with these problems, ex-situ plasma cleaning has recently been adopted, in which the cleaning gas is activated by a remote plasma source and flows into the interior of the chamber. Ex-situ plasma cleaning using remote plasma is excellent in the cleaning effect of the interior of the chamber, but the activated cleaning gas is disabled due to collision or reaction during the process of reaching the chamber from the remote plasma source, which ultimately has the problem of reducing the cleaning efficiency.

[0007] Patent document 1 relates to a cleaning method for a thin film deposition device, which discloses a cleaning method comprising the following steps: supplying a cleaning gas to a nozzle installed inside a cavity of the thin film deposition device; plasmatizing the cleaning gas inside the nozzle; and spraying the plasmatized cleaning gas into the interior of the cavity, thereby cleaning the interior of the cavity.

[0008] Patent Document 2 relates to a process chamber cleaning method, which discloses a cleaning method particularly suitable for PECVD equipment, wherein remote plasma is applied to the process chamber when cleaning the inside of the process chamber.

[0009] However, there is still a demand in the art for a more efficient cleaning process: adjusting the cleaning capacity according to the area in the process chamber, reducing the cleaning time while improving the cleaning efficiency, and reducing the amount of cleaning gas used, thereby improving productivity and reducing costs.

[0010] The prior art refers to the technical information that the inventor possesses in order to derive the present invention or that he or she acquires in the process of deriving the present invention, and is not necessarily the known technology disclosed to the public before the application of the present invention.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Korean Patent Publication No. 10-2008-0062112 (published on July 3, 2008)

[0014] Patent Document 2: Korean Patent Publication No. 10-2003-0060145 (published on July 16, 2003) Summary of the invention

[0015] Technical issues

[0016] In order to solve the above-mentioned problems, the object of the present invention is to provide a cavity cleaning method, wherein the free radical dissociation rate of the cleaning gas is significantly improved to improve the cleaning efficiency of the process chamber, effectively remove the by-products deposited in the above-mentioned process chamber, and effectively reduce the factors that may cause process defects.

[0017] In addition, an object of the present invention is to provide a method for cleaning a chamber, wherein the concentration of dissociated free radicals is adjusted according to the chamber area of ​​the process chamber that needs to be cleaned, so that the cleaning ability can be fully exerted at the desired position.

[0018] In addition, an object of the present invention is to provide a method for cleaning a chamber, wherein the cleaning time consumed for cleaning the chamber and the amount of cleaning gas used are reduced, thereby improving productivity and cost efficiency.

[0019] The problems to be solved by the present invention are not limited to the problems mentioned above, and ordinary technicians in the technical field to which the present invention belongs can clearly understand other technical problems to be solved that are not mentioned through the following description.

[0020] Solutions to the problem

[0021] According to one embodiment of the present invention, a cavity cleaning method comprises the following steps: generating a remote plasma source (RPS) plasma in an RPS; supplying free radicals into the cavity from the RPS plasma; generating a direct plasma in-situ in the cavity; and adjusting the morphology of the direct plasma by impedance tuning at the bottom of the cavity.

[0022] In this case, the RPS plasma may be formed using a cleaning gas including a gas, wherein the gas is an inert gas, a carbon fluoride (C x F y ) gases, nitrogen and fluorine (N x F y ) type gas, or a gas containing a fluorine (F) component, a chlorine (Cl) component, an oxygen component (O) or a combination thereof.

[0023] In this case, the direct plasma may be formed using an inert gas.

[0024] In the cavity cleaning method according to the embodiment of the present invention, the impedance tuning of the lower part of the cavity is performed so that the plasma density in the area to be cleaned is higher than that in other areas.

[0025] In this case, the impedance tuning of the lower portion of the cavity may be achieved by adjusting the impedance on the path leading to the lower electrode of the cavity.

[0026] In the step of adjusting the morphology of the direct plasma, the impedance of the lower part of the cavity is reduced so that the plasma density in the central part of the cavity is higher than the plasma density at the edge and inner wall of the cavity.

[0027] At this time, the radio frequency (RF) current flowing toward the lower portion of the cavity may be greater than the RF current flowing toward the inner wall of the cavity.

[0028] At this time, the dissociated free radicals may be concentrated in the central portion of the cavity rather than in the edge and inner wall of the cavity.

[0029] In the step of adjusting the direct plasma state, the impedance of the lower portion of the cavity may be increased in order to make the plasma density at the edge and inner wall of the cavity higher than the plasma density at the center of the cavity.

[0030] At this time, the RF current flowing toward the inner wall of the cavity may be greater than the RF current flowing toward the lower portion of the cavity.

[0031] At this time, the dissociated free radicals may be concentrated on the edge and inner wall of the cavity rather than the central portion of the cavity.

[0032] Effects of the Invention

[0033] As described above, the cavity cleaning method according to the present invention can significantly increase the free radical dissociation rate of the cleaning gas to improve the cleaning efficiency of the process cavity, effectively remove the by-products deposited in the process cavity, and effectively reduce the factors that may cause process defects.

[0034] Furthermore, according to the chamber cleaning method of the present invention, the concentration of dissociated free radicals is adjusted according to the chamber area of ​​the process chamber to be cleaned, so that the cleaning ability can be fully exerted at the desired position.

[0035] In addition, according to the chamber cleaning method of the present invention, the cleaning time consumed by chamber cleaning and the amount of cleaning gas used are reduced, thereby improving productivity and cost efficiency.

[0036] The effects of the present invention are not limited to the effects mentioned above, and a person skilled in the art can clearly understand other effects not mentioned through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure is a schematic diagram showing a substrate processing device capable of executing a chamber cleaning method according to an embodiment of the present invention.

[0038] Figure 2a and Figure 2b To show Figure 1 Schematic diagram of forming plasmas of different forms through impedance tuning in a substrate processing apparatus shown in FIG.

[0039] Figure 3 FIG. 1 is a process flow chart showing an example of a chamber cleaning method according to an embodiment of the present invention.

[0040] Figure 4 To show Figure 1 Schematic diagram of an example of an impedance control circuit in the substrate processing apparatus shown in .

[0041] Figure 5 To show Figure 1 0 is a process flow chart of an example of an impedance tuning method in the substrate processing apparatus shown in .

[0042] (Explanation of Reference Numerals)

[0043] 100: substrate processing device 110: chamber

[0044] 120: substrate support 121: substrate placement portion

[0045] 122: drive shaft 124: heater

[0046] 125: Lower electrode 130: Upper electrode

[0047] 140: RPS 145: Matching circuit network

[0048] 150: Gas source 160: RF power supply

[0049] 170: Impedance control circuit 180: Measurement sensor DETAILED DESCRIPTION

[0050] In the present invention, the drawings are exaggerated for the sake of distinction, clarity and ease of understanding of the prior art. In addition, the terms described below are defined in consideration of the functions in the present invention, and may vary according to the intentions or conventions of the users and operators. Therefore, these terms should be defined by the technical content of the full text of this specification. In addition, the embodiments are only illustrative matters of the structural elements disclosed in the claims of the present invention, and do not limit the scope of rights of the present invention, which should be interpreted according to the technical ideas of the full text of the specification of the present invention.

[0051] Throughout the specification, when it is mentioned that a structure “includes” another structure, unless there is a special description to the contrary, it means that other structures may also be included, rather than excluding other structures.

[0052] In addition, when it is mentioned that a structure is “connected”, “coupled” or “combined” to another structure, it refers not only to the case of “direct connection”, “direct coupling” or “direct coupling”, but also to the case of “connection with another structure in between”, “coupled with another structure in between” or “combined with another structure in between”. On the contrary, when it is mentioned that a structure is “directly connected”, “directly coupled” or “directly coupled” to another structure, it should be understood that there is no other structure in between.

[0053] In addition, when directional terms such as "front", "rear", "up", "down", "left", "right", "one end", "the other end", "both ends" are used, these are terms used illustratively for the orientation of the disclosed drawings and, therefore, should not be interpreted restrictively. When terms such as "first" and "second" are used, these are terms used to distinguish between structures and should not be interpreted restrictively.

[0054] In order to more clearly illustrate the features of the embodiments of the present invention, detailed descriptions of matters known to those skilled in the art of the following embodiments will be omitted. Also, in the drawings, detailed descriptions of parts not related to the description of the embodiments will be omitted.

[0055] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0056] Figure 1 The figure is a schematic diagram showing a substrate processing device capable of executing a chamber cleaning method according to an embodiment of the present invention.

[0057] Reference Figure 1 A substrate processing apparatus 100 capable of executing a chamber cleaning method according to an embodiment of the present invention includes a chamber 110, a substrate support 120, an upper electrode 130, a remote plasma source (RPS) 140, an external gas source 150, a radio frequency (RF) power supply 160, an impedance control circuit 170, and a measurement sensor 180.

[0058] The substrate processing apparatus 100 may be an apparatus for performing etching, deposition or other various processes when manufacturing semiconductors or displays. For example, a plasma processing process may be implemented by the substrate processing apparatus 100 .

[0059] The chamber cleaning method according to an embodiment of the present invention may be used to clean the substrate processing apparatus 100 .

[0060] The chamber 110 may include an inner space 110 c for performing a process of treating the substrate W, and the inner space 110 c may be sealed from the outside. The chamber 110 may include a sidewall 110 s and pins (not shown) for forming the inner space 110 c.

[0061] The shape of the cavity 110 is not limited, and may have various known shapes. The cavity 110 may be configured alone or in combination of two or more.

[0062] The chamber 110 maintains airtightness during the process of processing or cleaning the substrate W, and the vacuum degree of the internal space 110 c can be adjusted by a pressure regulating device.

[0063] The substrate support 120 is a component for placing the substrate W, and may have a shape facing the bottom surface of the upper electrode 130. For example, the substrate support 120 may include: a substrate placement portion 121 for placing the substrate W; and a driving shaft 122 extending downward from the bottom surface of the center portion of the substrate placement portion 121.

[0064] The substrate placement part 121 can be formed in various forms to support the substrate W, and a heater 124 can be provided inside as required to heat the substrate W. In addition, a lower electrode 125 is formed on the substrate placement part 121, and RF power is transmitted through a transmission line 88, and the transmission line 88 is connected from the plasma PL to the lower ground 99 terminal, and the plasma PL is generated in the internal space 110c of the chamber 110.

[0065] According to an embodiment of the present invention, the substrate placement portion 121 may be formed by an electrostatic chuck that supplies power to the lower electrode 125 and generates an electrostatic force on the substrate W. The lower electrode 125 may be formed as a whole or may be divided into a plurality of parts.

[0066] The driving shaft 122 is moved in the up-down direction by a driving unit (not shown) and can place the substrate W flowing into the inner space 110 c through the opening of the chamber 110 on the substrate placement unit 121 .

[0067] The upper electrode 130 may be partially or entirely formed of a conductive material so as to be supplied with the RF power RFi from the RF power supply source 160 .

[0068] Furthermore, the upper electrode 130 is disposed on the upper side of the chamber 110 to supply the inert gas introduced from the gas source 150 or the radicals in the RPS plasma supplied from the RPS 140 into the chamber 110. The inert gas flowing into the chamber 110 through the upper electrode 130 may be converted into plasma between the upper electrode 130 and the lower electrode 125.

[0069] The upper electrode 130 may be formed in various shapes such as a nozzle, a shower head, etc. For example, the upper electrode 130 may be formed in a shower head having a plurality of supply holes of a distribution plate disposed on the bottom surface, and the inert gas or free radicals may be supplied to the upper space of the substrate W through the plurality of supply holes.

[0070] In the RPS 140, when the inert gas and the cleaning gas are supplied, they are converted into plasma by the high frequency electric field. That is, the RPS plasma generated in the RPS 140 can be formed by the inert gas and the cleaning gas. The RPS 140 can adjust the plasma ratio of the inert gas and the cleaning gas by applying RF power.

[0071] When plasma is generated in the RPS 140 , radicals present in the plasma may be introduced into the upper electrode 130 and supplied into the chamber 110 .

[0072] Examples of the inert gas may include argon (Ar), helium (He), nitrogen (N), xenon (Xe), krypton (Kr), or a combination thereof, but are not limited thereto.

[0073] The cleaning gas may include fluorocarbon (C x F y ) gases, nitrogen and fluorine (N x F y ) type gas, or a gas containing a fluorine (F) component, a chlorine (Cl) component, an oxygen (O) component or a combination thereof.

[0074] The above fluorocarbon (C x F y ) type of gas may include carbon tetrafluoride gas (CF4), hexafluoroethane gas (C2F6), octafluoropropane gas (C3F8), octafluorocyclobutane (C4F8) or a combination thereof.

[0075] The above nitrogen and fluorine (N x F y ) type of gas may include nitrogen trifluoride (NF3).

[0076] The gas containing fluorine (F) component may include sulfur hexafluoride gas (SF6), hydrogen fluoride gas (HF), silicon tetrafluoride gas (SiF4) or a combination thereof.

[0077] The gas containing chlorine (Cl) component may include chlorine gas (Cl2), boron trichloride gas (BCl3), carbon tetrachloride gas (CCl4), silicon tetrachloride gas (SiCl4) or a combination thereof.

[0078] The gas containing oxygen (O) component may include oxygen (O 2 ), ozone (O 3 ) or a combination thereof.

[0079] In one embodiment, the RPS 140 may include a plasma generator provided with electrodes for forming plasma, an RF power supply for applying an electric field, a gas source for supplying gas to the plasma generator, a pipeline for supplying plasma formed in the plasma generator to the chamber 110, etc. However, the detailed configuration of the RPS 140 is not limited thereto, and the configuration of the RPS 140 known in the technical field may be used in the embodiments of the present invention.

[0080] The gas source 150 may supply an inert gas into the chamber 110 through the upper electrode 130 .

[0081] In one embodiment, the connection portion from the RPS 140 to the upper electrode 130 and the connection portion from the gas source 150 to the upper electrode 130 may be combined with each other.

[0082] In one embodiment, Figure 1 The positions of the RPS 140 and the gas source 150 shown in FIG. 1 may be changed to each other.

[0083] The RF power supply 160 may generate RF power RFi in the form of a sine wave, and may supply the RF power RFi to the upper electrode. The RF power supply 160 may be provided with a frequency adjustment unit for adjusting the frequency of the generated RF power. The frequency adjustment unit adjusts the output frequency without changing the output power output from the RF power supply 160, thereby adjusting the reactance element of the output impedance of the RF power supply 160 within a fine range Xc. The RF power RFi generated from the RF power supply 160 may be generated at a variety of frequencies, and the frequency adjustment range may be set to the rated frequency (e.g., 1356 MHz) of the RF power supply 160 or above.

[0084] A matching circuit network 145 is provided between the RF power source 160 and the upper electrode 130 to match the output impedance of the RF power source 160 with the load impedance of the cavity 110 . Thus, the RF output RFi generated from the RF power source 160 is supplied without being reflected by the cavity 110 .

[0085] The RF power RFi supplied to the upper electrode 130 excites a portion of the inert gas supplied from the upper electrode 130 , and may generate direct plasma PL in situ.

[0086] The impedance control circuit 170 may be disposed on the transmission line 88 extending from the lower electrode 125 of the substrate support 120. The impedance control circuit 170 may be used to adjust the shape of plasma by adjusting the impedance of the lower portion of the chamber 110, or may be used to reduce the magnitude of the RF power moving 66 toward the sidewall surface ground along the sidewall 110s of the chamber 110, and increase the magnitude of the RF transmission power R Fo transmitted 77 to the lower ground 99 through the lower electrode 125.

[0087] The measuring sensor 180 may be used to measure an effective current value and an effective voltage value passing through the impedance control circuit 170 .

[0088] According to the embodiment of the present invention, the dissociation rate of free radicals is increased and the morphology of plasma is adjusted by tuning the impedance of the lower part of the cavity 110, thereby maximizing the cleaning efficiency according to the area of ​​the cavity 110 that needs to be cleaned. That is, according to the embodiment of the present invention, the impedance on the path from the cavity 110 to the lower electrode 125 is adjusted, thereby making the plasma density in the area that needs to be cleaned higher than the plasma density in other areas of the cavity 110.

[0089] In the following content, reference will be made to Figure 4 and Figure 5 An example of the impedance control circuit 170 , the measurement sensor 180 , and impedance tuning using the same will be described.

[0090] The chamber cleaning method according to an embodiment of the present invention may be performed to remove byproducts attached to the inner wall or components of the chamber 110 of the substrate processing apparatus 100 having the structure described above. Figure 2a , Figure 2b and Figure 3 In order to avoid repetition, the details of Figure 1 A detailed description of the above-mentioned substrate processing apparatus 100 is shown in FIG.

[0091] Figure 2a and Figure 2b To show Figure 1 Schematic diagram of forming plasmas of different forms through impedance tuning in a substrate processing apparatus shown in FIG. Figure 3 FIG. 1 is a process flow chart showing an example of a chamber cleaning method according to an embodiment of the present invention.

[0092] exist Figure 1 , Figure 2a and Figure 2b In the substrate processing apparatus 100 shown in FIG. 1 , various semiconductor manufacturing processes can be performed. Most of them are performed in the chamber 110, where plasma is generated from an inactive gas and reacts with a substrate or a thin film on the substrate, thereby performing deposition, etching or other processing processes. During the execution of such a process, unreacted components or etching byproducts are attached and accumulated in the chamber 110. As described above, the byproducts attached to the chamber 110 can be removed by a chamber cleaning method according to an embodiment of the present invention.

[0093] Reference Figure 3 In step (S10), RPS plasma may be generated by RPS.

[0094] In the RPS plasma generation step ( S10 ), an inert gas and a cleaning gas are supplied to the RPS 140 , and a high frequency electric field is applied by an RF power supply to generate plasma.

[0095] By applying the RF electric field, the plasma conversion ratio of the inert gas and the cleaning gas, that is, the existence ratio of active species such as ions and radicals, can be adjusted.

[0096] In one embodiment, the inert gas may include argon (Ar), helium (He), nitrogen (N), xenon (Xe), krypton (Kr) or a combination thereof, but is not limited thereto.

[0097] In one embodiment, the cleaning gas may include fluorocarbon (C x F y ) gases, nitrogen and fluorine (N x F y ) type gas, or a gas containing a fluorine (F) component, a chlorine (Cl) component, an oxygen (O) component or a combination thereof.

[0098] The above fluorocarbon (C x F y ) type of gas may include carbon tetrafluoride gas (CF4), hexafluoroethane gas (C2F6), octafluoropropane gas (C3F8), octafluorocyclobutane (C4F8) or a combination thereof.

[0099] The above nitrogen and fluorine (N x F y ) type of gas may include nitrogen trifluoride (NF3).

[0100] The gas containing fluorine (F) component may include sulfur hexafluoride gas (SF6), hydrogen fluoride gas (HF), silicon tetrafluoride gas (SiF4) or a combination thereof.

[0101] The gas containing chlorine (Cl) component may include chlorine gas (Cl2), boron trichloride gas (BCl3), carbon tetrachloride gas (CCl4), silicon tetrachloride gas (SiCl4) or a combination thereof.

[0102] The gas containing oxygen (O) component may include oxygen (O 2 ), ozone (O 3 ) or a combination thereof.

[0103] In the step ( S20 ), radicals may be supplied from the RPS plasma to the chamber 110 .

[0104] In the radical supplying step ( S20 ), the radicals present in the RPS plasma generated in the step ( S10 ) are introduced into the chamber 110 through the upper electrode 130 .

[0105] In one embodiment, in the above step (S10), when NF3 is used as the cleaning gas to generate the RPS plasma, there is NF2 * NF * 、F * In the step ( S20 ), the free radicals as described above that are present in the plasma generated in the step ( S10 ) may be supplied to the chamber 110 through the upper electrode 130 .

[0106] The radicals supplied to the chamber 110 may be disposed in a space between the substrate support 120 and the upper electrode 130 .

[0107] In the step ( S30 ), direct plasma PL can be generated in-situ in the chamber 110 .

[0108] In the direct plasma generating step ( S30 ), the inert gas is supplied from the gas source 150 into the chamber 110 through the upper electrode 130 , and the RF power RFi is supplied from the RF power supply 160 to the upper electrode 130 , thereby converting the inert gas into plasma.

[0109] At this time, the output impedance of the RF power source 160 is matched with the load impedance of the cavity 110 by the matching circuit network 145 provided between the RF power source 160 and the upper electrode 130. Thus, the RF output RFi generated from the RF power source 160 can be supplied in a manner that is not reflected by the cavity 110.

[0110] Examples of the inert gas may include argon (Ar), helium (He), nitrogen (N), xenon (Xe), krypton (Kr), or a combination thereof, but are not limited thereto.

[0111] In this case, the free radicals supplied from the RPS 140 to the chamber 110 may be further dissociated, thereby increasing the free radical dissociation rate and ultimately improving the cleaning efficiency.

[0112] For example, NF2 * The free radicals further dissociate into NF * 、F * of free radicals, thereby ensuring a high free radical dissociation rate.

[0113] In the step ( S40 ), the shape of the direct plasma may be adjusted by tuning the impedance of the lower portion of the chamber 110 .

[0114] In the direct plasma PL morphology adjustment step ( S40 ), the impedance of the lower portion of the chamber 110 is tuned so that the plasma density in the area to be cleaned is higher than that in other areas of the chamber 110 .

[0115] In one embodiment, the impedance tuning of the lower portion of the cavity 110 may be achieved by adjusting the impedance on the path leading to the lower electrode 125 of the cavity 110 .

[0116] More specifically, when RF power is supplied from the RF power supply 160 to the upper electrode 130, the RF power is supplied to the cavity 110 through the matching circuit network 145, thereby, an RF current It flows from the RF power supply 160 to the upper electrode 130. The RF current may be branched into an RF current Iw flowing toward the inner wall of the cavity 110 through the plasma in the cavity 110 and an RF current Ib flowing toward the lower electrode 125 and the lower portion of the cavity 110 through the plasma in the cavity 110.

[0117] In order to improve the cleaning efficiency of the chamber 110, it is necessary to adjust the plasma density, uniformity, shape, etc. according to the area in the chamber 110. To this end, it is necessary to control the ratio of the RF current Iw flowing to the inner wall of the chamber 110 and the RF current Ib flowing to the lower part of the chamber 110. The sum of the two RF currents is the RF current It, which is constant, and therefore, the RF current Ib can be adjusted by adjusting the impedance on the path leading to the lower electrode 125.

[0118] In one embodiment, in the direct plasma PL morphology adjustment step (S40), in order to make the plasma density in the central portion of the cavity 110 higher than the plasma density in the edge and inner wall of the cavity 110, the impedance of the lower portion of the cavity 110 is reduced.

[0119] In this case, the RF current Ib flowing toward the lower portion of the cavity 110 may be greater than the RF current Iw flowing toward the inner wall of the cavity 110 .

[0120] exist Figure 2a An example of the substrate processing apparatus 100 that performs the above-described direct plasma PL morphology adjustment is shown.

[0121] like Figure 2a As shown, the direct plasma PL is disposed at the center of the chamber 110 between the upper electrode 130 and the substrate holder 120, and is not disposed at the edge and inner wall of the chamber 110. Even if it is disposed at the edge and inner wall of the chamber 110, it is disposed at a low density. That is, the plasma density at the center of the chamber 110 can be formed to be higher than the plasma density at the edge and inner wall of the chamber 110. In addition, the dissociated radicals are concentrated at the center of the chamber 110 compared to the edge and inner wall of the chamber 110.

[0122] Through the above process, when plasma is formed at a high density in the central portion of the chamber 110 as shown in FIG. 2 a , the cleaning efficiency of the central portion can be improved compared to the edge and inner wall of the chamber 110 .

[0123] In another embodiment, in the direct plasma PL morphology adjustment step (S40), in order to make the plasma density in the edge and inner wall of the cavity 110 higher than the plasma density in the central part of the cavity 110, the impedance of the lower part of the cavity 110 is increased.

[0124] In this case, the RF current Iw flowing toward the inner wall of the cavity 110 may be greater than the RF current Ib flowing toward the lower portion of the cavity 110 .

[0125] exist Figure 2b An example of the substrate processing apparatus 100 that performs the above-described direct plasma PL morphology adjustment is shown.

[0126] like Figure 2b As shown, the direct plasma PL may be disposed in the space between the upper electrode 130 and the substrate support 120 and the edge and inner wall of the chamber 110, and the plasma density in the edge and inner wall of the chamber 110 may be formed to be higher than the plasma density in the central portion of the chamber 110. Furthermore, dissociated radicals may be concentrated in the edge and inner wall of the chamber 110 compared to the central portion of the chamber 110.

[0127] Through the above process, Figure 2b In the case where plasma is formed at a high density at the edge and the inner wall of the chamber 110 , the cleaning efficiency of the edge and the inner wall can be improved compared to the central portion of the chamber 110 .

[0128] According to the present embodiment, by adjusting the impedance of the lower portion of the chamber 110 as described above and adjusting the plasma morphology, more effective cleaning can be achieved according to the region of the chamber 110 that needs to be cleaned.

[0129] In addition, according to this embodiment, non-in-situ cleaning using remote plasma and in-situ cleaning using modulated direct plasma are applied simultaneously, thereby reducing the cleaning time when the same cleaning gas is used, and reducing the amount of cleaning gas used when the same cleaning time is applied.

[0130] Therefore, according to the cavity cleaning method of this embodiment, the productivity of the process is improved and the cost-effectiveness can be improved.

[0131] Reference Figure 4 and Figure 5 , an example of the impedance control circuit 170, the measuring sensor 180, and impedance adjustment using the same will be described.

[0132] Figure 4 To show Figure 1 A schematic diagram of an example of an impedance control circuit in a substrate processing apparatus shown in FIG. Figure 5 To show Figure 1 0 is a process flow chart of an example of an impedance adjustment method in the substrate processing apparatus shown in FIG. Figure 4 and Figure 5 The impedance control circuit and impedance adjustment method shown in are shown as an example, and the present invention is not limited to this.

[0133] according to Figure 4 and Figure 5 In the embodiment shown in , the RF transmission power RFo transmitted 77 to the lower ground 99 can be set to the maximum, and the size of the RF power moving 66 along the side wall 110s of the cavity 110 toward the side wall surface ground can be further reduced.

[0134] Reference Figure 4 The impedance control circuit 170 may be configured to have a first filter 170A and a second filter 170B in parallel. The first filter 170A is provided with a variable capacitor Cc, which selectively cuts off the low-frequency power LF and allows the high-frequency power HF to pass through. The second filter 170B is configured to have an inductor L and a capacitor with a very small capacitance value connected in series, which selectively cuts off the high-frequency power HF and allows the low-frequency power LF to pass through.

[0135] Therefore, when the RF power RFi generated in the RF power supply 160 is a high frequency power HF of 1356 MHz or more, it cannot pass through the second filter 170B, but is transmitted to the lower ground 99 through the first filter 170A. Therefore, the second filter 170B is not provided with an inductor, but the variable capacitor Cc is provided in series. However, the embodiment of the present invention is not limited to this, and includes a structure in which the variable capacitor Cc of the first filter 170A is connected in series or in parallel with other capacitors.

[0136] In addition, according to another embodiment of the present invention, in the substrate processing step, similarly to the deposition step, when the high frequency power HF of 1356 MHz or higher is used, the second filter 170B that functions as a low frequency filter can be omitted. The reactance of the imaginary component of the plasma impedance is greater than 0, and therefore, the impedance control circuit 170 may be composed of only capacitors having a reactance value less than 0.

[0137] At this time, the RF transmission power R Fo transmitted to the chamber 110 through the upper electrode 130 is defined by cosθ (where θ is the phase difference between the voltage and the current) of the product of the voltage V and the current I flowing in the transmission line 88. The input power RFi supplied to the chamber 110 is all consumed in the plasma, so if the RF transmission power RFo in the transmission line 88 is measured after the plasma is generated, it is measured as "0". However, the transmission power RFo is "0" because the phase difference between the voltage V and the current I is formed to be 90 degrees, so that cosθ=0, and therefore, the voltage V and the current I may have values ​​other than "0". Therefore, if the capacitance value of the variable capacitor Cc of the first filter 170A of the impedance control circuit 170 is determined so that the product of the voltage V and the current I flowing in the transmission line 88 satisfies the maximum value, the RF power value RFo transmitted to the chamber 110 can be maximized. At this time, the voltage V and the current I are alternating currents in the form of sinusoidal waves, and therefore the capacitance value of the variable capacitor Cc is determined to maximize the product of the effective values ​​rms.

[0138] More specifically, if Figure 4 As shown, for the processing of the substrate, the following processing conditions are set: the process gas that meets the purpose of the processing is supplied by the upper electrode 130, the pressure and temperature of the chamber 110 are adjusted to a preset value or range, and the substrate W is heated by the heater 124 of the substrate holder 120 as required, etc., thereby, the processing (S110) can be performed according to the processing conditions.

[0139] The RF power RFi generated by the RF power supply 160 generates plasma PL on the upper side of the substrate W, and as the phase difference between the voltage V and the current I becomes 90 degrees, the RF transmission power RFo transmitted to the chamber 110 becomes "0". However, the voltage V and the current I of the RF transmission power RFo may not be "0", so the effective voltage Vrms and the effective current Irms of the RF transmission power RFo are measured by the measurement sensor 180, and the effective voltage Vrms and the effective current Irms measured by the measurement sensor 180 are transmitted to the control unit (not shown).

[0140] At this time, when the frequency of the RF power RFi generated in the above-mentioned RF power supply 160 is a high frequency above 1356 MHz, it cannot pass through the inductor L of the above-mentioned second filter 170B. Therefore, in the high-frequency RF transmission power RFo, the amount of power transmitted 77 to the above-mentioned lower ground 99 becomes different according to the capacitance value of the above-mentioned variable capacitor Cc of the above-mentioned first filter 170A.

[0141] Therefore, for the capacitance value of the variable capacitor Cc in the impedance control circuit 170, the changeable range is adjusted in the form of increasing or decreasing by a preset increment △C (S120), and the effective voltage value Vrms and the effective current value Vrms of the RF transmission power RFo can be measured in the measuring sensor 180 arranged between the lower ground 99 of the transmission line 88 and the impedance control circuit 170 (S130).

[0142] The increment ΔC is defined by the number of result values ​​obtained by multiplying the effective voltage value Vrms and the effective current value Vrms of the RF transmission power RFo. For example, if n result values ​​are to be obtained, the increment ΔC is obtained by (the maximum capacitance (Cmax) of the variable capacitor - the minimum capacitance (Cmin) of the variable capacitor) / (n-1). For example, if the capacitance value of the variable capacitor Cc varies from 10pF to 500pF, and about 99 result values ​​are to be obtained, the increment ΔC can be determined as (500pF-10pF) / (99-1)=5pF.

[0143] To this end, first, with the first capacitance value C1 of the variable capacitor Cc set to the minimum value of 10 pF, the effective voltage value Vrms and the effective current value Vrms of the RF transmission power RFo are measured, and their product is obtained as the first result value R1.

[0144] Furthermore, 15pF, which is an increment of 5pF ΔC, is added to 10pF as the first capacitance value as the second capacitance value C2, and the effective voltage value Vrms and the effective current value Vrms of the RF transmission power RFo are measured, and the product thereof is obtained as the second result value R2. Thereafter, 20pF, which is an increment of 5pF ΔC, is added to 15pF as the second capacitance value C2 as the third capacitance value C3, and the effective voltage value Vrms and the effective current value Vrms of the RF transmission power RFo are measured, and the product thereof is obtained as the third result value R3. The above-described method is repeated, and finally, 500pF, which is an increment of 5pF ΔC, is added to 495pF as the 98th capacitance value as the 99th capacitance value C99, and the effective voltage value Vrms and the effective current value Vrms of the RF transmission power RFo are measured, and the product thereof is obtained as the 99th result value R99. That is, in a state where the nth capacitance value of the variable capacitor Cc is set, the effective voltage value Vrms and the effective current value Vrms of the RF transmission power RFo are measured in this state, and their product is obtained as the nth result value (S140).

[0145] Thus, the capacitance value of the variable capacitor Cc in the first filter 170A of the impedance control circuit 170 is increased by an increment ΔC from the first capacitance value C1, thereby obtaining the first result value R1 to the 99th result value R99 about the 99th capacitance value C99. The change of the 99 capacitance values ​​(C1, C2, ..., C99) is completed in a very short moment by the electric signal, and the effective voltage value Vrms and the effective current value Vrms of the RF transmission power RFo changed thereby are also obtained in a very short moment by the electric signal.

[0146] That is, without being affected by the type of process gas or the supply amount per unit time or the pressure and temperature of the above-mentioned chamber 110, the effective voltage value Vrms and the effective current value Vrms of the RF transmission power RFo can be immediately obtained according to the change in the capacitance value of the above-mentioned variable capacitor Cc. Therefore, the time consumed to obtain 99 result values ​​(R1, R2, ..., R99) is very short.

[0147] In addition, in the method illustrated above, in order to illustrate the principle of the present invention, 99 result values ​​are obtained as an example, but the present invention is not limited to this. It can be configured to obtain roughly hundreds or thousands of result values, and the time consumed here is a very short time of tens of msec to hundreds of msec.

[0148] Then, the control unit sets the 66th capacitance value C66 of the variable capacitor Cc that satisfies the maximum value (for example, R68) among the obtained 99 result values ​​(R1, R2, ..., R99) as the applicable capacitance value of the variable capacitor Cc under the above-determined processing conditions (S150). Thus, the RF transmission power RFo transmitted 77 to the lower ground 99 through the lower electrode 125 can be set to the maximum, so the magnitude of the RF power moving 66 along the side wall 110s of the plasma chamber 110 to the side wall surface ground can be further reduced.

[0149] In addition, considering the measurement error and the like in the 99 result values ​​(R1, R2, ..., R99), for the capacitance values ​​of the variable capacitors Cc separated from each other, the maximum value can be more than 2 within the preset allowable error range. For example, considering the measurement error and the like, when the allowable error range is set to 3W, when the 42nd result value R42 of the 42nd capacitance value C42 is 110W and the 66th result value R66 of the 66th capacitance value C66 is 111W, it is difficult to judge that the 66th result value R66 is larger than the 42nd result value R42. In this case, considering that the maximum value of the allowable error is more than 2, the effective current value Irms affecting the RF transmission power RFo is greater than the effective voltage value Vrms, so the value of the larger effective current value Irms obtained when calculating the two 42nd result values ​​R42 and the 66th result value R66 that meet the maximum value of the result values ​​(R1, R2, ..., R99) is determined as the maximum value.

[0150] Furthermore, the variable capacitor Cc of the impedance control circuit 170 is kept in an adjusted state by the applicable capacitance value obtained in the adjustment circuit setting step, and the substrate is subjected to a cleaning process. Furthermore, if the cleaning condition of the substrate is changed, the aforementioned steps (S120) to (S150) are performed in a short time, the applicable capacitance value of the variable capacitor Cc is changed, and the efficiency of the RF transmission power RFo discharge 77 to the ground is maintained at a high state through the transmission line 88.

[0151] As described above, the effective current value Irms and the effective voltage value Vrms are measured in a very short time, and the result value obtained from their product is used to determine the applicable capacitance value of the variable capacitor Cc of the above-mentioned impedance control circuit 170. The above-mentioned impedance control circuit 170 forms plasma on the upper part of the above-mentioned substrate and adjusts the absolute value of the generated reactance component to be smaller, thereby guiding it to flow smoothly along the above-mentioned transmission line 88 to the above-mentioned lower ground 99.

[0152] In other words, most of the RF power RFi supplied from the RF power supply 160 is used to generate the plasma PL, and the RF transmission power RFo in the chamber 110 is 0 W. However, this is because the phase difference θ between the voltage value and the current is 90 degrees, resulting in 0 W. The voltage V and current I components have values ​​other than 0. If they are set to an applicable capacitance value of the variable capacitor Cc of the impedance control circuit 170 that satisfies the maximum value of the product of the effective voltage value Vrms and the effective current value Irms, the cleaning efficiency of the substrate can be improved.

[0153] As described above, the present invention is described with reference to the embodiments shown in the accompanying drawings, but this is only for illustration, and it should be understood that various modifications and other equivalent embodiments can be made according to the common knowledge in the technical field. Therefore, the true technical protection scope of the present invention should be based on the attached claims and defined according to the specific content of the above invention.

[0154] Industrial Applicability

[0155] The invention relates to a cavity cleaning method, which can be used in industrial fields related to semiconductor device or display manufacturing.

Claims

1. A method for cleaning a cavity, characterized in that: The steps include: generating an RPS plasma in a remote plasma source; supplying free radicals into the chamber from the RPS plasma; Generating a direct plasma in-situ in the chamber; and The morphology of the direct plasma is adjusted by tuning the impedance of the lower part of the cavity.

2. The cavity cleaning method according to claim 1, characterized in that: The RPS plasma is formed using a cleaning gas comprising a gas, The gas is an inert gas, a carbon-fluorine gas, a nitrogen-fluorine gas, or a gas containing a fluorine component, a chlorine component, an oxygen component or a combination thereof.

3. The cavity cleaning method according to claim 1, characterized in that: The direct plasma is formed using an inert gas.

4. The method for cleaning a cavity according to claim 1, characterized in that: In the above-mentioned cavity cleaning method, the impedance of the lower part of the cavity is tuned so that the plasma density in the area to be cleaned is higher than that in other areas.

5. The method for cleaning a cavity according to claim 1, characterized in that: The impedance tuning of the lower part of the cavity is achieved by adjusting the impedance on the path leading to the lower electrode of the cavity.

6. The method for cleaning a cavity according to claim 1, characterized in that: In the step of adjusting the morphology of the direct plasma, the impedance of the lower part of the cavity is reduced so that the plasma density in the central part of the cavity is higher than the plasma density at the edge and inner wall of the cavity.

7. The method for cleaning a cavity according to claim 6, characterized in that: The radio frequency current flowing toward the lower part of the cavity is made greater than the radio frequency current flowing toward the inner wall of the cavity.

8. The method for cleaning a cavity according to claim 6, characterized in that: The dissociated free radicals are concentrated in the central portion of the cavity as compared to the edge and inner wall of the cavity.

9. The method for cleaning a cavity according to claim 1, characterized in that: In the step of adjusting the direct plasma state, the impedance of the lower portion of the cavity is increased so that the plasma density at the edge and inner wall of the cavity is higher than the plasma density at the center of the cavity.

10. The cavity cleaning method according to claim 9, characterized in that: The radio frequency current flowing toward the inner wall of the cavity is greater than the radio frequency current flowing toward the lower part of the cavity.

11. The method for cleaning a cavity according to claim 9, characterized in that: The dissociated free radicals are concentrated on the edge and inner wall of the cavity rather than the central portion of the cavity.

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