Plasma processing device, internal component of plasma processing device, and method for manufacturing internal component of plasma processing device

Abstract

In order to provide a plasma processing apparatus or an internal member thereof that improves the yield of processing, or a method for manufacturing the same, the apparatus comprises a processing chamber disposed inside a vacuum vessel and in which plasma is formed inside, and a member disposed inside the processing chamber and having a surface facing the plasma, wherein the member has a coating on its surface composed of a material comprising at least one of yttrium oxide, yttrium fluoride, and yttrium oxyfluoride, and an element that becomes a +4 or +6 ion with an ionic radius smaller than that of a +3 yttrium ion, wherein the coating comprises a material comprising oxygen in a molar ratio of at least 1.5 times that of yttrium on average and fluorine in a molar ratio of at least 1 time, preferably at least 1.4 times that of yttrium.

Description

Technology Field

[0001] The present disclosure relates to a plasma processing apparatus for forming plasma within a processing chamber inside a vacuum vessel and processing a sample to be processed, such as a semiconductor wafer, placed within the processing chamber, an internal member of the plasma processing apparatus, and a method for manufacturing the internal member of the plasma processing apparatus. In particular, the invention relates to a plasma processing apparatus or a member for a plasma processing apparatus having a protective film on a surface facing the plasma within the processing chamber, or a protective film and a method for manufacturing the same. Background Technology

[0002] In the process of manufacturing semiconductor devices such as electronic devices or magnetic memory by processing semiconductor wafers, plasma etching (referred to as plasma etching) is applied for fine processing to form circuit structures on the surface of the semiconductor wafer. With the increasing integration of semiconductor devices, processing by such plasma etching requires even higher processing precision and higher yield.

[0003] In the manufacturing of electronic devices and semiconductor devices such as magnetic memory, plasma etching is applied for microfabrication. Since the inner wall of the processing chamber of a plasma processing apparatus used for plasma etching is exposed to high-frequency plasma and etching gas during the etching process, the inner wall surface is protected by forming a film with excellent plasma resistance. The following are known conventional technologies regarding materials for such plasma-resistant films.

[0004] Japanese Patent Publication No. 2004-197181 (Patent Document 1) describes that a material constituting a film covering the surface of an earth portion disposed inside a plasma etching device comprises a Group IIIA element (at least one selected from Sm, Eu, Gd, Tb, Dy, Ho, Er, Y, Tm, Yb, Lu as the main component) and a fluorine element, and contains a Group IIIIA fluoride phase, and furthermore, this fluoride phase is orthorhombic and contains 50% or more of a crystal phase belonging to the space group Pnma.

[0005] Japanese Patent Publication No. 2009-176787 (Patent Document 2) describes that the surface film of the earth portion disposed inside a plasma etching device is composed of a material containing one or more of Al2O3, YAG, Y2O3, Gd2O3, Yb2O3, or YF3.

[0006] Japanese Patent Publication No. 2014-141390 (Patent Document 3), Japanese Patent Publication No. 2016-27624 (Patent Document 4), and Japanese Patent Publication No. 2018-82154 (Patent Document 5) describe forming a film of yttrium oxide, yttrium fluoride, or yttrium oxyfluoride having an average crystallite size of less than 100 nm by an aerosol deposition method as a film material for an earth portion disposed inside a plasma etching device.

[0007] In Japanese Patent Publication No. 2016-539250 (Patent Document 6), the material of the surface film of the earth portion of a plasma etching device is Y3Al5O 12 , Y4Al2O9, Er2O3, Gd2O3, Y2O3, Er3Al5O 12 , Gd3Al5O 12It is described that it includes YF3 or Nd2O3, Y4Al2O9 and a Y2O3-ZrO2 solid solution. The said Y2O3-ZrO2 solid solution is zirconia in which the high-temperature phase is stabilized by adding yttria, and is a material well known as yttria-stabilized zirconia.

[0008] Japanese Patent Publication No. 2017-190475 (Patent Document 7) describes that the crystal structures of rare earth fluorides of Y, Sm, Eu, Gd, Er, Tm, Yb, and Lu have a high-temperature type (hexagonal) and a low-temperature type (orthorhombic), and that a phase change occurs and cracks occur when cooling from the sintering temperature, and that if a small amount of, for example, Y2O3 is added to yttrium-based fluorides, the crystals are partially stabilized, the shape of the cracks changes, and surface cracks are reduced.

[0009] International Publication No. 2017 / 043117 (Patent Document 8) describes stabilizing oxyfluoride yttrium with CaF2.

[0010] It is known that a general method for reducing the high-temperature phase involves reheating and slow cooling to transform the remaining high-temperature phase into a low-temperature phase. However, in this method, crystal growth proceeds and the crystallites become coarse. For example, in the embodiment of Patent Document 1, a film with 100% rectangular crystals is shown, but the crystal size is 1 μm or larger.

[0011] Meanwhile, in “Kazuhiro Ueda, Kazuyuki Ikenaga, Tomoyuki Tamura, Makoto Kadoya, ‘Review of Crystal Structure and Foreign Substance Generation Mechanism of Yttrium-based Materials for Plasma Etching Devices’, X-ray Analysis Research Roundtable of the Japan Society of Analytical Chemistry (Editor), 50 Advancements in X-ray Analysis, Agnes Technology Center, Issue Date: April 1, 2019, pp. 197-205” (Non-patent Literature 1), it is disclosed that increasing the average crystallite size leads to an increase in the generation of foreign substances. In addition, Japanese Patent Publication No. 2019-192701 (Patent Document 9) discloses that by making the crystallite size of the film of the earth portion placed inside a plasma processing device 50 nm or less, the generation of foreign matter on the semiconductor wafer processed inside is reduced, and by keeping the temperature of the substrate of the earth portion within a predetermined range when forming the film, the low-temperature phase ratio can be 60% or more and the crystallite size 50 nm or less.

[0012] In addition, "Masayuki Takashima, Kentaro Kano, Masahiko Kawase, 'Formation of Yttrium Fluorid-Stabilized Zirconia and Electrical Conductivity', Electrochemistry and Industrial Physical Chemistry, Vol. 53, No. 2, 1985, Issue Date: February 5, 1985, pp. 119-124" (Non-patent document 2) contains academic research on yttrium fluoridated zirconia (YF3-ZrO2).

[0013] If the high-temperature phase is stabilized at room temperature, the high-temperature phase does not undergo a phase change to the low-temperature phase during plasma discharge, so it is expected that the generation of foreign substances caused by phase change can be prevented.

[0014] In “Akihide Kuwahara, Yuichi Kihara, Kento Sakuma, ‘Evaluation of Phase Stability of Stabilized Zirconia by First Principles Molecular Orbital Calculations’, Materials, Vol. 50, No. 6, 2001, Issue Date: June 15, 2001, pp. 619-624” (Non-patent Literature 3), the stabilization of zirconia (ZrO2) is Zr 4+ Y with a smaller number 3+The decrease in the coordination number of Zr due to the oxygen ion vacancy effect introduced by ions, and Zr 4+ It is derived from first-principles calculations that lattice distortion caused by introducing ions larger than the ion radius (80 pm) is a factor.

[0015] Patent Document 8 describes a technique for stabilizing and partially stabilizing the high-temperature phase of oxyfluoride yttrium by adding CaF2 to yttrium oxide and yttrium fluoride and sintering them. This method is Y 3+ Ca, who is smaller than the singer 2+ It suggests that high-temperature stabilization is possible by introducing ions and utilizing the co-occurrence effect of fluoride ions or oxygen ions.

[0016] Patent Document 7 states that adding a small amount of Y2O3 to yttrium-based fluoride partially stabilizes the high-temperature phase and changes the shape of the cracks, thereby reducing surface cracks. With an elemental composition of Y, O, and F, stabilization of the high-temperature phase due to vacancy effects or lattice distortion calculated as stabilization of zirconia is not possible. Therefore, it is believed that the Y2O3-YF3 of Patent Document 7 reduces cracks through factors different from the stabilization and partial stabilization of the high-temperature phase.

[0017] In “Masao Sato, Shunhei Fukuda, ‘Preparation of Yttrium Iron Garnet Single Crystals by YF3-PbF2 Molten Salt Bath’, Journal of the Ceramic Industry Association, Vol. 71, No. 805, 1963, Issue Date: 1963, pp. 101-104” (Non-patent Literature 4), it is shown that 15 mol% of yttrium oxide dissolves in a molten yttrium fluoride at 1260°C. Prior art literature

[0018] Japanese Patent Publication No. 2004-197181, Japanese Patent Publication No. 2009-176787, Japanese Patent Publication No. 2014-141390, Japanese Patent Publication No. 2016-27624, Japanese Patent Publication No. 2018-82154, Japanese Patent Publication No. 2016-539250, Japanese Patent Publication No. 2017-190475, International Publication No. 2017 / 043117, Japanese Patent Publication No. 2019-192701

[0019] Kazuhiro Ueda, Kazuyuki Ikenaga, Tomoyuki Tamura, Makoto Kadoya, "Review of Crystal Structure and Foreign Contamination Mechanism of Yttrium-based Materials for Plasma Etching Devices," X-ray Analysis Research Roundtable of the Japanese Society of Analytical Chemistry (Editor), 50 Advancements in X-ray Analysis, Agne Technology Center, Issue Date: April 1, 2019, pp. 197-205. Masayuki Takashima, Kentaro Kano, Masahiko Kawase, "Formation of Yttrium Fluoride-Stabilized Zirconia and Electrical Conductivity," Electrochemistry and Industrial Physical Chemistry, Vol. 53, No. 2, 1985, Issue Date: February 5, 1985, p. 119-124 Akihide Kuwahara, Yuichi Kihara, Kento Sakuma, "Evaluation of Phase Stability of Stabilized Zirconia by First-Principle Molecular Orbital Calculations," Materials, Vol. 50, No. 6, June 15, 2001, pp. 619-624 Masao Sato, Shunhei Fukuda, "Preparation of Yttrium Iron Garnet Single Crystals by YF3-PbF2 Molten Salt Bath," Journal of the Ceramic Industry Association, Vol. 71, No. 805, 1963, pp. 101-104 The problem to be solved

[0020] However, in the above-mentioned conventional technology, problems arose because the following points were not sufficiently considered.

[0021] In other words, as the precision of processing required for plasma processing devices used for plasma etching increases, the size (e.g., diameter) of foreign matter generated during plasma etching processing within the processing chamber located inside the vacuum vessel of the plasma processing device is also decreasing. Thus, it is required to suppress the generation of fine particles (foreign matter) with smaller diameters. Furthermore, it is required to continue suppressing the generation of foreign matter even when the plasma processing device is operated continuously for a long period of time.

[0022] In the above-mentioned conventional technology using rare earth oxides as coatings, conditions for producing a thermal spray coating capable of sufficiently suppressing the above-mentioned corrosion or the generation of fine particles (also referred to as foreign matter) were not sufficiently considered because the coating is fluorinated by the plasma treatment gas. Furthermore, in the above-mentioned conventional technology using rare earth fluorides, conditions for producing a thermal spray coating capable of sufficiently suppressing the above-mentioned corrosion or the generation of fine particles were not sufficiently considered because the coating is oxidized by the plasma treatment gas. In addition, in the case of rare earth oxyfluorides, in the above-mentioned conventional technology, conditions for producing a thermal spray coating capable of sufficiently suppressing the above-mentioned corrosion or the generation of fine particles were not sufficiently considered because the coating undergoes a phase change when oxidized by the plasma treatment gas.

[0023] That is, the prior art described in Patent Document 8 involves adding CaF2 to yttrium oxide and yttrium fluoride and sintering them to stabilize or partially stabilize the high-temperature phase of oxyyttrium fluoride. This prior art is Y 3+ Ca2, which is smaller than the singer + It suggests that high-temperature stabilization is possible by introducing ions and utilizing the co-occurrence effect of fluoride ions or oxygen ions.

[0024] Patent Document 7 states that when a small amount of Y2O3 is added to yttrium-based fluoride, the high-temperature phase is partially stabilized, changing the shape of the cracks and reducing surface cracks. With an elemental composition of Y, O, and F, stabilization of the high-temperature phase due to vacancy effects or lattice distortion calculated as stabilization of zirconia is not possible. Therefore, it is believed that the Y2O3-YF3 of Patent Document 7 reduces cracks through factors different from the stabilization and partial stabilization of the high-temperature phase.

[0025] As such, in Patent Documents 7 and 8, it is believed that YF3 and YOF are (partially) stabilized by adding Y2O3 and CaF2, thereby suppressing crack formation during film deposition. However, since they are fluorinated and oxidized by the plasma treatment gas, conditions for producing a thermal spray film capable of sufficiently suppressing the above corrosion or the generation of fine particles have not been sufficiently considered.

[0026] In addition, a general method for reducing the high-temperature phase described in Patent Document 8 is to reheat and slowly cool, thereby transforming the remaining high-temperature phase into a low-temperature phase. However, this method causes crystal growth to proceed and crystallites to coarsen. In the embodiment of Patent Document 1, a film with 100% rectangular crystals is shown, but the crystal size is 1 μm or larger. On the other hand, Patent Document 9 describes a method in which the low-temperature phase ratio is 60% or more and the crystallite size is 50 nm or smaller, but it is difficult to achieve a high low-temperature phase ratio exceeding 70-80%.

[0027] Non-patent document 4 indicates that yttrium oxide is dissolved at 15 mol% in a fluorinated yttrium melt at 1260°C. In the prior art, it is known that in fluorine-rich YOF films, YF3 is segregated at the grain boundaries of YOF particles. For this reason, in Y2O3-YF3, YF3 and YOF are eventually separated, and the molar ratio of YF3 to YOF becomes 3:2. From this, it is believed that in the Y2O3-YF3 of patent document 7, the YOF in YF3 becomes a pinning site and stops the propagation of cracks.

[0028] As described above, in conventional technology, contamination of the sample to be treated occurred due to generated particles (foreign matter), and the treatment yield was impaired.

[0029] The object of the present disclosure is to provide a plasma treatment apparatus or an internal member thereof, or a method for manufacturing the internal member thereof, which improves the yield of treatment by reducing the occurrence of foreign substances.

[0030] Other problems and novel features will become apparent from the description in this specification and the accompanying drawings. means of solving the problem

[0031] A brief overview of the representative items of the present disclosure is as follows.

[0032] The above objective is achieved by a plasma processing apparatus or a member for a plasma processing apparatus having a processing chamber disposed inside a vacuum vessel and having plasma formed inside, and a member disposed inside the processing chamber and having a surface facing the plasma, wherein the member has a coating on its surface composed of a ceramic crystal material comprising yttrium oxyfluoride and a fluoride or oxyfluoride of an element that becomes a +4 or +6 ion with an ionic radius smaller than that of a +3 yttrium ion, or an oxide, fluoride, or oxyfluoride of said element and yttrium, wherein the coating comprises oxygen at a molar ratio of at least 1.5 times that of yttrium and fluorine at least 1.4 times that of yttrium as an average, and said ceramic crystal material. Effects of the invention

[0033] According to the plasma treatment apparatus or the component thereof according to the present disclosure, it is possible to reduce the occurrence of foreign substances from the film on the surface of the component disposed in the treatment chamber. By doing so, contamination of the sample to be treated caused by foreign substances is reduced, thereby improving the treatment yield of the sample to be treated. Brief explanation of the drawing

[0034] FIG. 1 is a cross-sectional view schematically showing the configuration of a plasma processing device according to an embodiment. FIG. 2 is a diagram showing the dependence of the average value of the crystallite size and the amount of foreign matter generated on plasma discharge time. FIG. 3 is a diagram showing the dependence of the average value of the crystallite size, the ratio of the high-temperature phase, and the amount of foreign matter generated on the plasma discharge time. Figure 4 is a correlation diagram between the ratio of the high-temperature phase and the amount of foreign matter generated by plasma discharge for a certain period of time. FIG. 5 is a schematic diagram illustrating a manufacturing method for forming a film on the surface of an earth electrode as shown in the embodiment of FIG. 1. Figure 6 is a diagram showing the relationship between the compositions of oxyfluoride, yttrium fluoride, and yttrium oxide. FIG. 7 is a diagram showing a table comparing the characteristics of a film formed by the prior art and a film of the present embodiment. Specific details for implementing the invention

[0035] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, in the following description, the same reference numerals are assigned to identical components and repeated descriptions may be omitted. Additionally, the drawings may be depicted schematically relative to the actual form to make the explanation clearer, but this is merely an example and does not limit the interpretation of the present disclosure.

[0036] (Example)

[0037] FIG. 1 is a cross-sectional view schematically showing the configuration of a plasma processing device according to an embodiment.

[0038] The plasma processing device (100) of the present embodiment is a plasma etching device and comprises a vacuum vessel having a cylindrical portion, a plasma forming part arranged to surround the cylindrical portion above or to the side, and a vacuum exhaust part including a vacuum pump arranged below the vacuum vessel to exhaust the inside of the vacuum vessel. A processing chamber (5), which is a space where plasma is formed, is arranged inside the vacuum vessel and configured to be in communication with the vacuum exhaust part.

[0039] The upper part of the processing chamber (5) is a space surrounded by a cylindrical inner wall and constitutes a discharge chamber where plasma (13) is formed. A stage (4) is arranged inside the processing chamber (5) below the discharge chamber where plasma (13) is generated. The stage (4) is a sample stand on which a wafer (3), which is a substrate to be processed, is placed and maintained on its upper surface. The plasma processing device (100) can perform an etching process (hereinafter simply referred to as processing) on ​​the wafer (3), which is a substrate to be processed, placed on the stage (4), for example.

[0040] The stage (4) is composed of a cylindrical member having a central axis in the vertical direction of the stage (4) positioned at a location that is concentric with or can be considered as such when viewed from above. A space is open between the bottom surface of the processing chamber (5), which has an opening communicating with the vacuum exhaust section, and the bottom surface of the stage (4), and the stage (4) is maintained at a position midway between the top surface and the bottom surface with respect to the vertical direction of the processing chamber (5). The internal space of the processing chamber (5) below the stage (4) is connected to the discharge chamber through a gap between the side wall of the stage (4) and the inner wall surface of the cylindrical processing chamber (5) surrounding the stage (4), thereby forming an exhaust path through which products formed on the upper surface of the wafer (3) and the discharge chamber, as well as plasma and gas particles inside the discharge chamber, pass through and are discharged to the outside of the processing chamber (5) by a vacuum exhaust part during the processing of the wafer (3) above the upper surface of the stage (4).

[0041] The stage (4) has a base material which is a metal member having a cylindrical shape. In the base material of the stage (4), a heater (not shown) disposed inside a dielectric film covering the upper surface of the base material, and a refrigerant flow path (not shown) disposed in multiple concentric or spirally around the central axis inside the base material. Additionally, with the wafer (3) placed on the upper surface of the dielectric film of the stage (4), a heat-conducting gas such as He is supplied to the gap between the lower surface of the wafer (3) and the upper surface of the dielectric film. For this reason, a pipe (not shown) through which the heat-conducting gas flows is disposed inside the base material and the dielectric film.

[0042] Additionally, the substrate of the stage (4) is connected via a coaxial cable through an impedance matching device (11) to a high-frequency power source (12) that supplies high-frequency power to form an electric field to attract charged particles in the plasma above the upper surface of the wafer (3) during the processing of the wafer (3) by plasma. Furthermore, above the heater in the dielectric film above the substrate of the stage (4), a film-shaped electrode (not shown) is installed to supply DC power to generate an electrostatic force within the dielectric film and the wafer (3) to adsorb and maintain the wafer (3) on the upper surface of the dielectric film. This electrode is symmetrically arranged around the central axis in the diameter direction from the upper and lower central axis of the approximately circular upper surface of the wafer (3) or the stage (4), and is configured to be able to assign different polarities to each of these multiple regions.

[0043] A window member (2) is provided above the upper surface of the stage (4) of the processing room (5). The window member (2) is positioned opposite the upper surface of the stage (4) and forms the upper part of the vacuum container. The window member (2) has the shape of a disc made of dielectric material, such as quartz or ceramic, which hermetically seals the inside and outside of the processing room (5). A shower plate (1) is provided below the window member (2) and at a position that forms the ceiling surface of the processing room (5), with a gap (6) between it and the lower surface of the window member (2). The shower plate (1) has the shape of a disc made of dielectric material, such as quartz, having a plurality of through holes (7) in its center.

[0044] The gap (6) is connected to a vacuum vessel to communicate with the treatment gas supply pipe (25). A valve (26) is provided at a designated location on the treatment gas supply pipe (25) to open or close the interior of the treatment gas supply pipe (25). The treatment gas (treatment gas) supplied to the interior of the treatment chamber (5) has its flow rate or speed controlled by a gas flow control means (not shown) connected to one end of the treatment gas supply pipe (25), and flows into the interior of the gap (6) through the treatment gas supply pipe (25) which is opened by the valve (26). The treatment gas that flows into the interior of the gap (6) then diffuses within the gap (6) and is supplied from the upper side of the treatment chamber (5) through the through hole (7) of the shower plate (1) into the treatment chamber (5).

[0045] A vacuum exhaust unit is positioned at the bottom of the vacuum vessel to discharge gas or particles inside the processing chamber (5). The vacuum exhaust unit discharges gas or particles inside the processing chamber (5) through an exhaust port, which is an exhaust opening positioned directly below the stage (4) at the bottom of the processing chamber (7) and positioned with the vertical center axis nearly identical. The vacuum exhaust unit is equipped with a pressure regulating plate (14) and a vacuum pump, a turbo molecular pump (10). The pressure regulating plate (14) is a disc-shaped valve that moves up and down above the exhaust port to increase or decrease the area of ​​the flow path through which gas flows into the exhaust port. The vacuum exhaust unit also has a roughing pump, a dry pump (9), and a valve (16). The outlet of the turbo molecular pump (10) is connected to the dry pump (9) through an exhaust pipe. A valve (16) is positioned on the exhaust pipe.

[0046] The pressure adjustment plate (14) also serves as a valve for opening and closing the exhaust port. The vacuum vessel is equipped with a pressure detector (27), which is a sensor for detecting the pressure inside the processing chamber (5). A signal output from the pressure detector (27) is transmitted to a control unit (not shown) to detect a pressure value. Based on the pressure value, the pressure adjustment plate (14) is driven according to a command signal output from the control unit. By doing so, the vertical position of the pressure adjustment plate (14) changes, and the area of ​​the exhaust flow path increases or decreases.

[0047] Among the valves (15) and (17) connected to the exhaust pipe (8), valve (15) is a slow exhaust valve for slowly exhausting the processing chamber (5) from atmospheric pressure to vacuum by the dry pump (9). Meanwhile, valve (17) is a main exhaust valve for exhausting at high speed by the dry pump (9).

[0048] A waveguide (19) and a magnetron oscillator (18) are arranged around the upper and side walls of the upper cylindrical portion of the vacuum vessel constituting the processing chamber (5). The waveguide (19) and the magnetron oscillator (18) are components for forming an electric field or magnetic field supplied to the processing chamber (5) to form plasma. That is, a waveguide (19), which is a conduit through which the electric field of microwaves supplied to the inside of the processing chamber (5) propagates inward, is arranged above the window member (2), and a magnetron oscillator (18) that generates and outputs the electric field of microwaves is arranged at one end thereof.

[0049] The waveguide (19) is equipped with a rectangular waveguide section and a circular waveguide section. The rectangular waveguide section has a rectangular cross-section and its axis extends in the horizontal direction, and a magnetron oscillator (18) is disposed at one end. The circular waveguide section is connected to the other end of the rectangular waveguide section, has a central axis extending in the vertical direction, and has a circular cross-section. At the lower end of the circular waveguide section, a cavity having a cylindrical shape with an increased diameter is disposed. The cavity is configured so that an electric field of a specific mode is strengthened inside it. Multiple solenoid coils (20) and solenoid coils (21), which are means for generating a magnetic field, are provided above and around the cavity, and further around the side of the processing room (5).

[0050] In the plasma processing apparatus (100) shown in FIG. 1, an unprocessed wafer (3) is transported into a processing chamber (5) by the tip of an arm of a vacuum transport device (not shown), such as a robot arm, which is placed inside a transport chamber, which is another vacuum vessel (not shown) connected to the side wall of the vacuum vessel. Then, the unprocessed wafer (3) at the tip of the arm is placed on the upper surface of a stage (4). When the arm of the vacuum transport device exits the processing chamber (5), the interior of the processing chamber (5) is sealed. Then, the unprocessed wafer (3) is maintained on the dielectric film by an electrostatic force generated by applying a DC voltage to an electrostatic adsorption electrode within the dielectric film of the stage (4). In this state, a gas having heat transfer properties, such as He, is supplied through a pipe arranged inside the stage (4) into the gap between the lower surface of the wafer (3) and the upper surface of the dielectric film constituting the upper surface of the stage (4). Additionally, a refrigerant whose temperature is adjusted to a predetermined range by a refrigerant temperature controller not shown is supplied to the refrigerant flow path inside the stage (4). By doing so, heat transfer between the temperature-adjusted substrate of the stage (4) and the wafer (3) is promoted, and the temperature of the wafer (3) is adjusted to a temperature value within a range suitable for the start of processing.

[0051] Processing gas, whose flow rate and speed are adjusted by a gas flow rate control means, passes through the processing gas supply pipe (25) and is supplied into the processing chamber (5) through the gap (6) and through the through hole (7). At the same time, the inside of the processing chamber (5) is exhausted from the exhaust port by the operation of the turbo molecular pump (10), and the pressure inside the processing chamber (5) is adjusted to a pressure value within a range suitable for processing by the balance between the two (supply of processing gas into the inside of the processing chamber (5) and exhaust of the inside of the processing chamber (5). In this state, the electric field of microwaves oscillated from the magnetron oscillator (18) propagates through the inside of the waveguide (19), passes through the window member (2) and the shower plate (1), and is radiated into the inside of the processing chamber (5). In addition, a magnetic field generated by a solenoid coil (20, 21) is supplied to the processing room (5), and an electron cyclotron resonance (ECR) is generated by the interaction between the magnetic field and the electric field of the microwave, and atoms or molecules of the processing gas are excited, ionized, and dissociated, thereby generating plasma (13) inside the processing room (5).

[0052] When the plasma (13) is formed, high-frequency power from the high-frequency power source (12) is supplied to the substrate of the stage (4), and a bias potential is formed above the upper surface of the wafer (3), and charged particles such as ions in the plasma (13) are attracted to the upper surface of the wafer (3), and the etching process of the film layer to be processed, which has a film structure including a plurality of film layers including a film layer to be processed and a mask layer formed on the upper surface of the wafer (3), proceeds along the pattern shape of the mask layer. When it is detected by a detector not shown that the processing of the film layer to be processed has reached its end point, the supply of high-frequency power from the high-frequency power source (12) is stopped, the plasma (13) is lost, and the processing is stopped.

[0053] When the control unit determines that there is no need to proceed further with the etching process of the wafer (3), high vacuum evacuation is performed. Additionally, after the static electricity is removed and the adsorption of the wafer (3) is released, the arm of the vacuum transport device enters the processing room (5), and the processed wafer (3) is transferred to the arm. After that, as the arm contracts, the wafer (3) is transferred to a vacuum transport room outside the processing room (5).

[0054] The inner wall surface of such a processing chamber (5) is a surface that faces the plasma (13) and is exposed to the particles. Meanwhile, in order to stabilize the potential of the dielectric plasma (13), it is necessary to place a member that functions as an earth electrode that faces the plasma and contacts it within the processing chamber (5).

[0055] In the plasma processing apparatus (100), the earth electrode (22) is positioned to cover the lower surface of the inner side wall (inner wall) of the processing chamber (5) surrounding the discharge chamber, with the purpose of functioning as an earth electrode. The earth electrode (22) is composed of a ring-shaped member positioned above the upper surface of the stage (4) to surround the lower surface of the inner wall of the processing chamber (5) surrounding the discharge chamber. The earth electrode (22) comprises a base material composed of a conductive material and a coating that covers the surface thereof. In this example, the base material of the earth electrode is composed of a metal such as a stainless steel alloy or an aluminum alloy.

[0056] If the earth electrode (22) does not have a coating on the surface of the base material, it is exposed to plasma (13) at the location (the part without a coating), so it may become a source of corrosion or foreign matter that causes contamination of the wafer (3). Therefore, in order to suppress contamination, a coating (24) made of a material with high plasma resistance is placed over the surface of the earth electrode (22) and covered by the earth electrode (22). By the coating (24), the earth electrode (22) can maintain its function as a plasma-based electrode covering the inner wall of the processing room (5), while suppressing damage caused by plasma on the earth electrode (22). The earth electrode (22) and the coating (24) placed over the earth electrode can be considered as internal members whose surfaces face the plasma. The membrane (24) is sometimes also called the skin (24).

[0057] Additionally, the film (24) may be a laminated film. In this embodiment, as the film (24), a film was used in which a plurality of yttrium oxide crystals, yttrium fluoride crystals, and yttrium oxyfluoride crystals were integrally deposited and formed on the surface of a base material of an earth electrode (22) having a surface roughness within a predetermined range, using atmospheric plasma spraying, suspension plasma spraying, explosive spraying, depressurized plasma spraying, aerosol deposition (AD), or physical vapor deposition (PVD), for example, yttrium oxide (Y2O3), yttrium fluoride (YF3), yttrium oxyfluoride (YOF), or a material containing one or more of these, and then formed using atmospheric plasma spraying, suspension plasma spraying, explosive spraying, depressurized plasma spraying, aerosol deposition (AD), or physical vapor deposition (PVD).

[0058] Meanwhile, in the substrate (23) of the inner wall of the processing room (5) that does not function as an earth electrode (22), a metal member such as a stainless steel alloy or an aluminum alloy is used. On the surface of the substrate (23), in order to suppress corrosion, metal contamination, and the occurrence of foreign matter caused by exposure to plasma (13), a passivation treatment, various thermal spraying, PVD, and chemical vapor deposition (CVD) are performed to improve corrosion resistance to plasma and reduce the consumption of the substrate (23).

[0059] Additionally, in order to reduce the interaction between the substrate (23) and the plasma (13), a cylindrical cover (not shown) made of ceramic, such as yttrium oxide or quartz, may be placed between the inner wall surface of the cylindrical substrate (23) and the discharge chamber. By placing such a cover between the substrate (23) and the plasma (13), contact with highly reactive particles within the plasma (13) or collisions with charged particles are blocked or reduced, thereby suppressing the consumption of the substrate (23).

[0060] The film (24) of this embodiment is manufactured based on the following findings.

[0061] As shown in Fig. 4 of Patent Document 9 (Japanese Patent Publication No. 2019-192701) and Fig. 5 of X-ray Analysis Advancement 50, pp. 197 (2019) (Non-patent Document 1), increasing the average crystallite size increases the occurrence of foreign substances on the semiconductor wafer in the plasma processing apparatus. Accordingly, Patent Document 9 discloses a technique for suppressing the occurrence of foreign substances by making the crystallite size of the film 50 nm or less.

[0062] On the other hand, as shown in Fig. 2, as the exposure time to plasma discharge increases, the average crystallite size of the film decreases, thereby reducing the amount of foreign matter generated per unit time. However, it can be seen that when the crystallite size is below 40 nm, the rate of size reduction decreases. Furthermore, as shown in Fig. 4 of Patent Document 9 and Fig. 5 of Non-Patent Document 1, even if the average crystallite size is reduced, the amount of foreign matter generated does not become zero.

[0063] Figure 2 is a diagram showing the correlation between plasma discharge time, amount of foreign matter generated, and crystallite size.

[0064] In FIG. 2, the bar graph shows the number of foreign substances generated when the film (24) is irradiated with plasma from the time (t1) at the left end of the bar to the time (t2) at the right end. Additionally, the number of foreign substances detected per unit time is shown as a white square (□) with the vertical axis on the left and the time irradiated with plasma (center of the irradiation time) as the horizontal axis, and the average crystallite size of the inner wall material irradiated with plasma is shown as a black circle (●) with the vertical axis on the right.

[0065] As shown in FIG. 2, as the exposure time to the plasma discharge increases, the number of foreign substances per unit time decreases, and the average size of the crystallites on the surface of the film (24) decreases. However, it can be seen that when the exposure time is below 40 nm, the rate of decrease in the average size of the crystallites decreases.

[0066] Figure 3 shows the results of examining the factors of foreign matter generation in the range where the average crystallite size is 40 nm or less. Even when the exposure time to plasma (horizontal axis) is increased, the average crystallite size (lower part of the right vertical axis), indicated by black circles (●), did not show significant changes centered around approximately 30 nm. On the other hand, the amount of foreign matter generated per unit time (number of foreign matter: left vertical axis), indicated by white squares (□), decreases as the exposure time to plasma (horizontal axis) increases. At this time, the ratio of low-temperature phases, such as rectangular or orthorhombic crystallites, to the total crystallites, indicated by black diamonds (◆), increases (low-temperature phase ratio: upper part of the right vertical axis). The ratio of this low-temperature phase is a ratio in which the sum (M1+M2) of the amount of low-temperature phase rectangular or orthorhombic crystals M1 (number or mass or volume) and the amount of high-temperature phase hexagonal crystals M2 (number or mass or volume) of the low-temperature phase material constituting the film (24) is used as the denominator, and the amount of low-temperature phase rectangular or orthorhombic crystals M1 is used as the numerator (M1) (ratio of low-temperature phase = M1 / (M1+M2)).

[0067] From the results shown in FIGS. 2 and FIGS. 3, it is believed that no foreign matter is generated when the average crystallite size of the film (24) is 40 nm or less and the ratio of hexagons does not change (the ratio of the low-temperature phase is between 0.6 and 0.7) with respect to changes in the time exposed to plasma. From this, it can be seen that when the film (24) of the present embodiment is used, several foreign matter is generated as a result of the cumulative time of processing multiple wafers (3) using plasma in the processing chamber (5). That is, it is preferable that the average value of the crystal size of the film (24) is 50 nm or less.

[0068] Based on these results, the correlation between the amount of foreign matter generated and the high-temperature phase is shown in FIG. 4. FIG. 4 is a correlation diagram between the ratio of the high-temperature phase and the amount of foreign matter generated during a plasma discharge for a certain period of time. In FIG. 4, the horizontal axis represents the ratio of the low-temperature phase or the high-temperature phase to the total of the material containing yttrium that constitutes the film (24) on the surface of the earth electrode (22) of the wafer (3) processed in the plasma processing device (100) according to the present embodiment, and the vertical axis represents the number of foreign matter detected from the surface of the wafer (3).

[0069] As shown in FIG. 4, it can be seen that as the proportion of the low-temperature phase increases (the proportion of the high-temperature phase decreases), the amount of foreign matter indicated by the black square (■) decreases. From this, it is assumed that the appearance of foreign matter can be suppressed by making the proportion of the high-temperature phase of the material containing yttrium constituting the film (24) relatively low.

[0070] As a general means to reduce such high-temperature phases, it is considered to transform the remaining high-temperature phase into a low-temperature phase by reheating and slow cooling. However, in this method, the crystal growth of the material containing yttrium proceeds, and the crystallites become larger. An example of a film having 100% rectangular crystals is shown in the embodiment of Patent Document 1, and the crystal size of the material constituting the film is 1 μm or larger.

[0071] Meanwhile, Patent Document 9 indicates that when forming a film by plasma spraying under atmospheric pressure conditions using a material containing yttrium fluoride, the surface temperature of the film can be maintained at a value within the range of 280°C or higher or 350°C or lower, as described in the examples and drawings of Patent Document 9, thereby allowing the ratio of the low-temperature phase, orthorhombic (orthorhombic), in the crystals of the film to be 60% or higher and the crystallite size to be 50 nm or lower. However, in reality, it is difficult to achieve a high ratio of the low-temperature phase (orthorhombic) exceeding 70% for a film material containing yttrium.

[0072] The Y2O3-ZrO2 solid solution described in Patent Document 6 is a zirconia in which yttria is added to stabilize the high-temperature phase, and is a material well known as yttria-stabilized zirconia. In addition, Non-Patent Document 2 contains academic research on yttrium-stabilized zirconia (YF3-ZrO2).

[0073] The initiators assumed that the hexagonal phase, which is the high-temperature phase of the material constituting the film (24), undergoes a phase change into the rectangular or orthorhombic phase, which is the low-temperature phase, at a specific temperature range (e.g., room temperature around 25°C), and that fine particles are generated due to this phase change of the crystal. They believed that by suppressing such phase changes and stabilizing the crystals of the high-temperature phase, the generation of foreign matter can be suppressed. That is, by stabilizing the high-temperature phase, it is difficult for the high-temperature phase to undergo a phase change into the low-temperature phase during plasma discharge, thereby preventing the generation of foreign matter caused by the phase change.

[0074] Non-patent literature 3 states that the stabilization of zirconia (ZrO2) is Zr 4+ Y with a smaller valence than the ion 3+ The decrease in the coordination number of Zr due to the oxygen ion vacancy effect with the introduction of ions, and Zr 4+ It is derived from first-principles calculations that lattice distortion caused by introducing ions larger than the ion radius (80 pm) is a factor.

[0075] In addition, Patent Document 8 describes a technique for stabilizing and partially stabilizing the high-temperature phase of oxyfluoride yttrium by adding CaF2 to yttrium oxide and yttrium fluoride and sintering them. From this, Y 3+ Ca, who is smaller than the singer 2+ It is suggested that high-temperature phase stabilization is possible by introducing ions and utilizing the co-occurrence effect of fluoride ions or oxygen ions. Additionally, Patent Document 7 describes that when Y2O3 is added to yttrium-based fluoride, the high-temperature phase is partially stabilized, the shape of the cracks changes, and surface cracks can be reduced.

[0076] However, according to the authors' review, in the composition of the elements Y, O, and F, stabilization of the high-temperature phase due to calculated vacancy effects or lattice distortion is not possible by stabilizing zirconia. From this, it is believed that Y2O3-YF3 of Patent Document 7 reduces cracks through factors different from high-temperature phase stabilization and partial stabilization.

[0077] On the other hand, Figure 1 of Non-Patent Document 4 shows that yttrium oxide is dissolved at 15 mol% in a fluorinated yttrium melt at 1260°C. In the prior art's examination, it was found that in a fluorine-rich YOF film, YF3 is segregated at the grain boundaries of YOF particles. This indicates that in Y2O3-YF3, YF3 and YOF are ultimately separated, and the molar ratio of YF3 to YOF becomes 3:2. From this, it is believed that in the Y2O3-YF3 of Patent Document 7, the YOF in YF3 becomes a pinning site, stopping the propagation of cracks.

[0078] According to the review of the initiators, the crystal structure of a film (24) in which a small amount of yttrium oxide (Y2O3) was added to yttrium-based fluoride was analyzed by XRD (X-ray Diffraction). As a result, the main layer of the film (24) was Y5O4F7, and the low-temperature phase yttrium fluoride (YF3) and the high-temperature phase (oxy-yttrium fluoride (YOF) and yttrium fluoride (YF3)) were contained at a rate of 40%. The crystallite size of Y5O4F7 was 35 nm. In addition, the elemental concentration of the film (24) was measured using fluorescent X-rays and was found to be Y: 32 at%, O: 9.4 at%, F: 58 at%.

[0079] As a result of analyzing the crystal structure and detecting the concentration of such a film (24) that was exposed to plasma discharge for a long time, it was found that the high-temperature phase YOF and the low-temperature phase YF3 decreased, Y5O4F7 increased, and the oxygen concentration increased with element concentrations of Y: 35 at%, O: 14 at%, and F: 51 at%. This indicates that the surface of the film (24) was oxidized along with a phase change. In the film (24) in which the amount of Y2O3 added was increased to increase the oxygen concentration, cubic Y2O3 was detected by XRD, and the crystallite size was large at 70 nm.

[0080] Therefore, the initiators also examined corrosion by oxidation and fluorination on the surface of a film (24) made of such YOF and Y2O3 materials. The Y2O3 on the surface of the film (24) is etched and fluorinated by exposure to a plasma discharge during the etching process of the wafer (3). In addition, the YF3 on the film (24) is oxidized in the same way.

[0081] That is, the film (24) exposed to plasma is a mixture of YOF, which corresponds to a molar ratio of 1:1 of Y2O3 and YF3, and Y5O4F7, which is a stable phase in the vicinity. Here, the surface of YOF also oxidizes if it is exposed for a long time to the plasma discharge formed during the processing of the wafer (3). From this, it is thought that if the molar ratio of Y:O of the material constituting the film (24) formed by thermal spraying is 1:1.5 or higher, it is difficult to oxidize even if exposed to plasma for a long time. Also, regarding F, it is thought that if the molar ratio of Y:F of the material of the film (24) is 1:1 or higher, and preferably 1:1.4 or higher, fluorination when exposed to plasma is suppressed.

[0082] Meanwhile, in Patent Document 8, in order to stabilize the high-temperature phase of oxyfluoride yttrium (at least partially), CaF2 is added to the YOF crystal to Y 3+ Ca, which has a lower valence than the ion. 2+ Ions are introduced. Consequently, it is assumed that the high-temperature phase is stabilized by the oxygen or fluoride ion vacancy effect. However, the occurrence of oxygen or fluoride ion vacancies leads to a decrease in resistance to oxygen plasma or fluoride plasma.

[0083] In addition, since the concentration of elements increases with fluorine but not with oxygen, the molar ratio of Y:F becomes 1:1 or higher, but the molar ratio of Y:O does not become 1:1.5 or higher. Because of this, when a film (24) made of a material in which CaF2 is added to YOF is exposed to plasma for a long time, oxidation proceeds on the surface of the film (24), and there is a risk that foreign matter may be produced.

[0084] So, the initiators, in the YOF decision, Y 3+ It was considered to introduce ions larger than the ionic radius (93 pm) and stabilize the film (24) by the lattice distortion effect. As for elements with an ionic radius larger than 93 pm as divalent or higher ions, Ce with an ionic radius of 101 pm was considered. 3+Wow, 99pm's Ca 2+ , Sr of 113pm 2+ It is limited to.

[0085] By adding CeO2, CaO2, and SrO, a coating (24) made of YOF, the crystal is (partially) stabilized, can be formed. The coating (24) can be formed using an atmospheric plasma spraying method (atmospheric plasma spraying, APS). The coating (24) formed using the atmospheric plasma spraying method can be formed by using a CeO2-YOF solid solution as the material, forming a plasma using gas directed toward the substrate to be coated under atmospheric pressure or a pressure close to it, and supplying particles of the coating material (24) into the plasma to melt them, and then spraying and depositing them onto the surface of the substrate.

[0086] The atmospheric plasma spray used to form the film (24) is explained using FIG. 5. FIG. 5 is a schematic diagram showing a manufacturing method for forming a film on the surface of an earth electrode as shown in the embodiment of FIG. 1.

[0087] As shown in FIG. 5, a spray gun (GN) is positioned at a distance from the surface of the substrate (23) and fine particles of the coating material (24) are introduced from the tip of the gun (GN) toward the plasma formed by using gas ejected from the gun (GN) toward the upper surface of the substrate (23), thereby melting or semi-melting the fine particles and spraying the fine particles onto the upper surface of the substrate (23) along the direction in which the plasma flows.

[0088] The spray gun (GN) is composed of a power source (203), a nozzle (201), and a material supply pipe (205). The nozzle (201) is electrically connected to the power source (203) and a predetermined voltage is applied from the power source (203). Additionally, the nozzle (201) is configured to eject argon (Ar) gas (GA) for plasma formation from an opening (OP1) at the tip. The material supply pipe (205) is positioned at a predetermined distance from the opening (OP1) at the tip of the nozzle (201). The material supply pipe (205) is configured to eject fine particles of material from its opening (OP2) in a direction that crosses the direction (202) in which the argon gas (GA) flows.

[0089] Additionally, the nozzle (201) has a central rod-shaped terminal (T1) and an outer cylindrical terminal (T2) surrounding the outer circumference of the terminal (T1) with a gap between them, each of which is electrically connected to the respective polarity terminals of the power source (203). The gap between the outer circumference of the central terminal (T1) is in communication with the opening (OP1) of the gas outlet at the tip of the nozzle (201) to form a gas supply path for argon gas (GA). The axial direction passing through the opening (OP1) of the gas outlet from the gas supply path for argon gas (GA) follows the direction of the ejection of argon gas (GA) from the tip of the nozzle (201), or the radiation direction of the plasma formed in front of the tip of the nozzle (201).

[0090] It is configured so that an arc discharge occurs in the space in front of the nozzle (OP1) by a high voltage applied to each terminal (T1, T2) of the nozzle (201) from the power source (203). Ar gas (GA), supplied to the gas supply path from a gas source not shown connected to the nozzle (201), is discharged from the gas nozzle (OP1) toward the upper surface of the substrate (23) as a gas flow (202), and an arc discharge occurs in the space in front of the nozzle (OP1) by applying a high voltage from the power source (203) to each terminal (T1, T2) of the nozzle (201). By the generated arc discharge, the Ar gas is excited, and a thermal spray frame (204) is formed between the nozzle (201) and the substrate (23). In this state, in the material supply pipe (205), the thermal spray material (206) passes through the internal flow path of the material supply pipe (205) together with the flow of the transport gas (207) and is introduced (supplied) toward the thermal spray frame (204) from the opening (OP2) at the tip of the material supply pipe (205). In this embodiment, the thermal spray material (206) is a fine particle of a coating material (24) in which the ratio of CeO2 to oxyfluoride yttrium is adjusted to 35 mol% or a value approximated to this.

[0091] Each particle constituting the thermal spray material (206) becomes molten or semi-molten and collides with and adheres to the surface of a substrate (23) composed of a material including aluminum or an aluminum alloy, following the flow (202) of plasma and Ar gas (GA) of the thermal spray frame (204). Then, each particle constituting the attached thermal spray material (206) solidifies on the surface of the substrate (23) as it cools. Each particle that has solidified and mutually welded covers a predetermined area of ​​the surface of the substrate (23) and is stacked upward until it reaches a desired thickness, thereby forming a film (208) (24). In this embodiment, this process is repeated to form a film (24) with a thickness of about 100 μm. Additionally, when the film (208) (24) is formed to a desired thickness, the distance between the nozzle (201) and the substrate (23) is set so that the semi-molten particles do not remain inside the film (24).

[0092] The film (24) according to the embodiment described below is formed using atmospheric plasma spraying as shown in FIG. 5. However, in the above example, in order to increase the molar ratio (concentration) of oxygen to 1.5 times or more of Y (yttrium) to improve resistance to oxygen and fluorine in the plasma, it is necessary to increase the amount of CeO2, CaO2, and SrO. However, since Ca and Sr are divalent positive ions, there is a risk of contaminating the semiconductor wafer, so it is not appropriate to increase the amount added too much.

[0093] The concentration of each element in the film (24) formed in this way was measured using fluorescent X-rays. As a result, on the surface of the film (24), Y: 20 at%, O: 45 at%, F: 22 at%, and Ce: 13 at%. In addition, it was detected that Y:O was 1:2.2 and Y:F was 1:1.1.

[0094] From the results of the analysis of the crystal structure by XRD, it was determined that the main layer was YOF (CeO2-YOF solid solution) and that trace amounts of YF3 and CeO2 crystals were present. In addition, the crystallite size of YOF was 40 nm, and the hexagonal ratio of the CeO2-YOF solid solution was about 90%. Meanwhile, when the crystal structure of the film (24) exposed to plasma for a long time was analyzed, almost no change in the hexagonal phase ratio was confirmed compared to the unexposed film.

[0095] Oxyfluoride has a hexagonal high-temperature phase and an oblong low-temperature phase, but since it is not clear whether the hexagonal phase can be used as the high-temperature phase when stabilized, it is described as hexagonal and oblong rather than high-temperature and low-temperature phases.

[0096] The above oxyfluoride is Y 3+ Wow O 2- and F - It consists of. The positive ion is Y 3+ Since that is all, in order to increase the oxygen concentration (molar ratio) in the film (24), 2F - Wow O 2- Although Y5O6F3, which exchanges Y, can be considered, it is not possible to increase the concentrations of both O and F relative to Y. Therefore, the initiators considered a method to increase the oxygen concentration by adding positive ions of an element different from Y.

[0097] YFSeO3, YFCO3, YFSO4, YFMoO4, YF(OH)2, etc., were examined as stable structures with additional elements in YOF. The ionic radius of the element added to these materials is Se 6+ : 42pm, C 4+ : 15pm, S 6+ : 29pm, Mo 6+ : 62pm and Y 3+ It is smaller than the ion radius (93 pm).

[0098] In oxyfluoride, Y 3+When a plasmon with a larger valence and an ionic radius smaller than that of is added, electrons remain. Additionally, the attachment of oxygen achieves coordination number matching. The ionic radius of the added element is Y 3+ It is thought that, although smaller, 2 to 3 oxygen atoms (ionic radius 14 pm) bond to an additional element, causing lattice distortion and stabilization.

[0099] In addition, YF(OH)2 is formed when hydrogen ions and oxygen ions combine to form (OH) - It becomes so that it is stabilized by causing lattice distortion with two oxygen atoms having an ionic radius of 14 pm (ignoring the size of a single proton). This is Y 3+ It is suggested that by adding a compound composed of Y, O, and F containing an element M that becomes a positive ion with an ionic radius less than or equal to that of the element, oxygen-rich divalent anions are introduced into oxygen sites, thereby promoting stabilization through a lattice distortion effect.

[0100] So, the initiators, Y 3+ We investigated whether high resistance to fluorine and oxygen in plasma could be obtained by adding element M, which becomes a positive ion with an ionic radius less than or equal to that of Y, to the YOF material, thereby increasing the oxygen concentration to 1.5 times or more of Y and the fluorine concentration to 1 time or more.

[0101] Element M is a +4 and +6 ion, and Y 3+ It needs to be smaller than the ionic radius of. In this case, C 4+ , Si 4+ , Ge 4+ , Zr 4+ , Hf 4+ , S 6+ , Cr 6+ , Se 6+ , Mo 6+ , Te 6+ , W 6+ Sn and Pb have divalent ionic radii of Y. 3+It was excluded because it is larger. Also, element M, which is 1 to 2 valence, was excluded because it is highly likely to be a cause of semiconductor contamination. That is, element M, which becomes a +4 valence or +6 valence ion, is at least one of C, Si, Ge, Zr, Hf, S, Cr, Se, Mo, Te, and W.

[0102] The film (24) of this embodiment is formed by spraying the material using atmospheric plasma, as described above, using oxyfluoride yttrium and oxides of elements M, Y, and F as materials. That is, in this example, high voltage is applied to the nozzle, and while argon gas is flowed as plasma gas, particles of a material containing oxyfluoride yttrium and YFCO3 particles in which element M is C (carbon) are introduced into the spraying frame formed by discharge, along with a transport gas, and molten particles are sprayed onto the surface of the substrate of the earth electrode (22) to form the film (24).

[0103] As a result of detecting the elemental concentration of such a film (24) using fluorescent X-rays, Y: 22 at%, O: 45 at%, F: 22 at%, C: 11 at%, Y:O: 1:2, and Y:F: 1:1. In addition, as a result of analyzing the crystal structure by XRD, crystals of YOF and Y(CO3)F were mixed on the surface of the film (24). The crystallite size of YOF was 28 nm, and hexagonal crystals were present in approximately 100% of the case.

[0104] In addition, regarding the film (24) exposed to plasma for a long time, the crystal structure was analyzed and compared with that before exposure, and no significant change in the hexagonal phase ratio was confirmed even after the exposure. In addition, no significant change in the molar ratio (concentration) of oxygen within the film (24) was likewise confirmed. In this example, since the added element M is carbon, it is assumed that the effect on the manufacturing process of the semiconductor device due to the addition is sufficiently small.

[0105] Next, a film (24) was formed using YFSO4, in which element M is S, as a material added to oxyfluoride yttrium, and the concentration of the elements was detected by fluorescence X-ray measurement. As a result, it was detected that Y: 25 at%, O: 42 at%, F: 25 at%, S: 7.5 at%, Y:O: 1:1.7, and Y:F:1:1. Likewise, as a result of analyzing the crystal structure by XRD, it was found that the main layer is YOF, YFSO4 is present in trace amounts, the crystallite size of YOF is 40 nm, and the ratio of the hexagon to the total is about 90%. In addition, even after prolonged exposure to plasma, no significant change was confirmed in the ratio of the hexagon to the oxygen concentration compared to the state before exposure.

[0106] In addition to the above-mentioned YFCO3 and YFSO4, YFSeO3 and YFMoO4 using Se and Mo as element M can also be used to form the film (24) in the same way. As another embodiment of such a film (24), the film (24) may be formed using a suspension plasma spraying method.

[0107] In the thermal spraying method described above, as in the example shown in FIG. 5, a high voltage is applied to the terminals of the central and outer parts of the nozzle (201) under atmospheric pressure conditions to generate an arc discharge, and the supplied Ar gas is plasma-ized to form a thermal spraying frame (204). A material containing particles of oxyfluoride and YFMoO4 suspended in a solvent is introduced into the thermal spraying frame (204) and, together with the solvent, a film (24) is formed by radiating and attaching it to the surface of the substrate (23) of the earth electrode (22). In this example, the thermal spraying temperature is set high so that the solvent in the thermal spraying frame (204) volatilizes by heating and the particles of the thermal spraying material (206) do not remain in the film (24) in a semi-molten state, and the distance between the nozzle (203) and the upper surface of the substrate (23) is set to a value within a predetermined range. As a material for forming the film (24), oxyfluoride, yttrium, YFCO3, YFSO4, and YFSeO3 may be used.

[0108] The concentration of elements in the film (24) detected as above was Y: 20 at%, O: 50 at%, F: 20 at%, Mo: 10 at%, Y:O: 1:2.5, and Y:F: 1:1. As for the crystal structure, it was found that the main layer was YOF, the crystallite size of YOF was 33 nm and the hexagonal phase was about 70%, and that even when exposed to plasma for a long time, no significant change in the hexagonal phase ratio was confirmed.

[0109] When forming a film (24) using a suspension plasma spraying method, in addition to the above, oxyfluoride yttrium, yttrium yttrium particles, and silicon dioxide powder suspended in a solvent may be used as spraying materials. It was confirmed that the elemental concentrations of the film (24) formed in this way are Y: 20 at%, O: 40 at%, F: 28 at%, Si: 12 at%, and that Y:O is 1:2 and Y:F is 1:1.4. Furthermore, as a result of analyzing the crystal structure in the same way, it was found that the film (24) has a main layer of Y5O4F7 and also contains YOF (thought to be SiO2-Y5O4F7, SiO2-YOF).

[0110] In addition, the crystallite size of Y5O4F7 is 30 nm, the hexagonal ratio is about 80%, and no significant change in the hexagonal phase ratio was observed even after prolonged exposure to plasma. In addition to silicon oxide, germanium oxide, hafnium oxide, sulfide oxide, selenium oxide, chromium oxide, molybdenum oxide, tellurium oxide, and tungsten oxide can be used.

[0111] In another embodiment, a film (24) was formed using PVD. The PVD target was a sintered material of oxyfluoride yttrium, and a chip of yttria-stabilized zirconia was placed on top of it to form the film.

[0112] In this example, the elemental concentrations of the film (24) were found to be Y: 25 at%, O: 42 at%, F: 28 at%, Zr: 5 at%, and Y:O: 1:1.7 and Y:F: 1:1. As a result of analyzing the crystal structure by XRD, the main layer of the film (24) was Y5O4F7, and Y2O3 and ZrO2 were not detected. The crystallite size of Y5O4F7 was 40 nm, and the hexagonal ratio was about 25%. When exposed to plasma for a long time, no significant change was detected in the ratio of hexagonal and tetragonal (tetragonal) phases compared to before exposure.

[0113] Likewise, a film (24) was formed by compression molding a mixture of finely ground sintered oxyfluoride and finely ground YFCO3 as a PVD target. Instead of YFCO3, YFSeO3, YFSO4, and YFMoO4 can be used.

[0114] In this case, the elemental concentrations of the film (24) were found to be Y: 25 at%, O: 50 at%, F: 25 at%, C: 25 at%, with Y:O being 1:2 and Y:F being 1:1. Additionally, as a result of analyzing the crystal structure by XRD, it was found that the film (24) was a mixture of crystals of YOF and Y(CO3)F, the crystallite size of YOF was 38 nm, and the ratio of hexagons was approximately 100%. Furthermore, even when exposed to plasma for a long time, no significant change in the ratio of hexagons was confirmed from that before exposure.

[0115] FIG. 6 shows the relationship between the compositions of yttrium oxyfluoride, yttrium fluoride, and yttrium oxide. The ternary system of YOF exists only on the line from Y:O=1:1.5 to Y:F=1:3. Since yttrium is a positive trivalent element, oxygen is a negative divalent ionic element, and fluorine is a negative 1 valent element, it does not deviate from this line without a positive trivalent element M other than yttrium. The scope of this embodiment corresponds to the shaded portion (60), and cannot be realized with only yttrium oxyfluoride, yttrium fluoride, and yttrium oxide, which are conventional technologies.

[0116] Y2O3 crystals are not oxidized even when treated with oxygen plasma. This is because, chemically, oxygen cannot be bonded in an amount exceeding 1.5 times that of yttrium. In order to bond oxygen exceeding 1.5 times that of yttrium, the presence of the positively charged element M is indispensable. Additionally, when Y2O3 crystals are treated with fluorine plasma, they become YOF~Y5O4F7, in which the Y:F ratio is in the range of 1:1 to 1:1.4. At this time, the Y:O ratio becomes 1:1 to 1:0.8. If hydrogen reduction treatment, such as HF gas plasma treatment, is involved, oxygen is removed and YF3 is formed; however, as can be seen in Fig. 6, since O decreases as F increases, the molar ratios Y:O ≥ 1:1.5 and Y:F ≥ 1:1 are incompatible.

[0117] The inner wall material, generally referred to as a YOF film, is a material containing Y, O, and F, for example, Y5O4F7, Y6O5F8, Y6O6F9, or a mixture of these with Y2O3 and YF3. Since all of these are materials that exist on the line segment (61) shown in FIG. 6, the molar ratio as the average of the entire YOF material obtained does not deviate from the line segment (61) of FIG. 6, regardless of the ratio in which these materials are mixed. Therefore, in either case where the wafer (3) is processed by a plasma using a gas containing oxygen or a plasma using a gas containing fluorine in the processing chamber (5), the composition of the YOF material constituting the film (24) on the surface of the earth electrode (22) exists on the line segment (61) of FIG. 6.

[0118] According to an examination of the composition of the film (24) performed under multiple conditions of the initiators, cases were detected where the composition deviated slightly from the line segment (61) in appearance, but this was determined to be due to the influence of by-products of plasma treatment (e.g., those formed by combining F or O with Cl remaining from plasma treatment using Cl2 gas), and the composition of the YOF that constituted the film (24) before treatment was determined to be on the line segment (61) of FIG. 6. That is, the three elemental materials of the YOF in the film (24) itself, due to changes in composition resulting from exposure to plasma, follow the line segment (61) of FIG. 6, but it is thought that there may be cases where the material of the film (24) does not follow the line segment (61) of FIG. 6 due to the influence of reaction products accompanying the treatment of the wafer (3).

[0119] In this embodiment, by adding element M to the inner wall material, the ratio of oxygen and fluorine concentrations within the inner wall material is shifted from the line (61) of FIG. 6 to the shaded area (60), the oxygen concentration and fluorine concentration are increased compared to the YOF inner wall material, and the reaction of radical oxygen or radical fluorine in the inner wall material by oxygen plasma and fluorine plasma is suppressed, thereby improving plasma resistance.

[0120] FIG. 7 is a diagram showing a table comparing the characteristics of a film formed by the prior art and a film (24) of the present embodiment. In the table TAB shown in FIG. 7, the qualitative superiority of the characteristics of the film formed by the prior art and the film (24) of the present embodiment is indicated in 4 stages (◎, ○, △, ×). In the film (24) of the present embodiment shown in FIG. 7, the material of the inner wall material is shown as a representative example, a material comprising oxyfluoride yttrium (YOF) and an oxide, fluoride, or fluorooxydide (CeO2, YFCO3, YFSO4, YFSeO3, YFMoO4, or SiO2) of element M (at least one of C, Si, Ge, Zr, Hf, S, Cr, Se, Mo, Te, W) which becomes a +4 or +6 valence ion.

[0121] The film of the prior art is an inner wall material that does not contain element M (no) and Ca, and the inner wall material is a portion of Y2O3, YF3, YOF, and YF3+CaF3. In addition, the film (24) of the present embodiment is a portion of element M that is Ce, C, S, Se, Mo, and Si, and the inner wall material is a portion of YOF+CeO2, YOF+YFCO3, YOF+YFSO4, YOF+YFSeO3, YOF+YFMoO4, and YOF+SiO2. As shown in FIG. 7, the film (24) of the present embodiment is marked with ◎ or ○ in terms of each characteristic of oxidation characteristics, fluoride resistance, and foreign matter generation, and can be considered to have superior characteristics compared to each characteristic of the film of the prior art.

[0122] In other words, the film (24) is a film composed of a material that includes at least one of yttrium oxide, yttrium fluoride, and yttrium oxyfluoride, and an element that becomes a +4 or +6 ion with an ionic radius smaller than that of a +3 yttrium ion, and includes oxygen in a molar ratio of at least 1.5 times yttrium on average and fluorine in a molar ratio of at least 1 time, preferably at least 1.4 times yttrium.

[0123] In addition, the material of the inner wall material constituting the film (24) is a material comprising at least one of yttrium oxide, yttrium fluoride, and oxyyttrium oxyfluoride, and an oxide of element M that becomes a +4 or +6 valence ion, or a fluoride, or a fluoride oxyfluoride. Yttrium oxide, yttrium fluoride, and oxyyttrium oxyfluoride are at least one of Y2O3, YF3, YOF, and Y5O4F7. In addition, the oxide of element M that becomes a +4 or +6 valence ion, or a fluoride, or a fluoride oxyfluoride is any one of YFCO3, YFSeO3, YFSO4, and YFMoO4. Furthermore, by making the average value of the crystallite size (size of the crystal) of the film (24) 50 nm or less, the occurrence of foreign matter is suppressed.

[0124] Although the disclosure made by the present discloser has been specifically described above based on examples, the present disclosure is not limited to the above examples and is of course possible to make various changes.

[0125] [Industrial Applicability]

[0126] The present disclosure is applicable to a plasma processing apparatus for processing a sample to be processed, such as a semiconductor wafer, an internal member of the plasma processing apparatus, and a method for manufacturing the internal member of the plasma processing apparatus. Explanation of the symbols

[0127] 1 : Shower plate 2 : Window component 3 : Wafer 4 : Stage 5 : Processing room 6 : Gap 7 : Through hole 8 : Exhaust pipe 9: Dry pump 10: Turbomolecular pump 11: Impedance Matching Circuit 12: High-frequency Power Supply 13: Plasma 14: Pressure adjustment plate 15 : Valve 16 : Valve 17: Valve 18: Magnetron oscillator 19: Waveguide 20: Solenoid coil 21: Solenoid coil 22: Earth electrode 23 : Material 24 : Coating 25: Treatment gas supply piping 26: Valve 27 : High vacuum pressure detector 201 : Nozzle 202: Gas flow 203: Power supply 204 : Warrior Frame 205 : Material Supply Pipe 206: Warrior Material 207: Transport Gas Flow

Claims

Claim 1 A plasma processing apparatus comprising: a processing chamber disposed inside a vacuum vessel and in which plasma is formed on the inside; and a member disposed inside the processing chamber and having a surface facing the plasma; wherein the member has a coating on its surface composed of a ceramic crystal material comprising oxyfluoride yttrium, a fluoride or oxyfluoride of an element that becomes a +4 or +6 ion with an ionic radius smaller than that of a +3 yttrium ion, or an oxide, fluoride, or oxyfluoride of said element and yttrium, wherein the coating comprises, on average, oxygen at a molar ratio of 1.5 times or more to yttrium and fluorine at a molar ratio of 1.4 times or more to yttrium, wherein the oxyfluoride yttrium comprises at least one of Y2O3, YF3, YOF, and Y5O4F7, and the ceramic crystal material comprises any one of YFCO3, YFSeO3, YFSO4, and YFMoO4. Claim 2 A plasma treatment apparatus according to claim 1, wherein the element that becomes a +4 or +6 ion is at least one of C, Si, Ge, Zr, Hf, S, Cr, Se, Mo, Te, and W. Claim 3 delete Claim 4 A plasma treatment device according to claim 1 or 2, wherein the film is formed by thermal spraying. Claim 5 delete Claim 6 An internal member of a plasma processing apparatus having a processing chamber disposed inside a vacuum vessel and formed with plasma on the inner side thereof, and an internal member disposed inside the processing chamber and having a surface facing the plasma, wherein the surface of the internal member is provided with a coating composed of a ceramic crystal material comprising oxyfluoride yttrium, a fluoride or oxyfluoride of an element that becomes a +4 or +6 ion with an ionic radius smaller than that of a +3 yttrium ion, or an oxide, fluoride, or oxyfluoride of said element and yttrium, wherein the coating comprises, on average, oxygen at a molar ratio of 1.5 times or more to yttrium and fluorine at a molar ratio of 1.4 times or more to yttrium, wherein the oxyfluoride yttrium comprises at least one of Y2O3, YF3, YOF, and Y5O4F7, and the ceramic crystal material comprises any one of YFCO3, YFSeO3, YFSO4, and YFMoO4. Claim 7 In claim 6, an internal member of a plasma processing apparatus in which the element that becomes a +4 or +6 ion is at least one of C, Si, Ge, Zr, Hf, S, Cr, Se, Mo, Te, and W. Claim 8 delete Claim 9 An internal member of a plasma treatment device, wherein, in claim 6 or 7, the film is formed by thermal spraying. Claim 10 delete Claim 11 A method for manufacturing an internal member that is disposed inside a vacuum vessel and disposed inside a processing chamber where plasma is formed on the inside, and whose surface faces the plasma, wherein a ceramic crystal material comprising yttrium oxyfluoride and a fluoride or oxyfluoride of an element that becomes a +4 or +6 ion with an ionic radius smaller than that of a +3 yttrium ion, or an oxide, fluoride, or oxyfluoride of said element and yttrium, is sprayed on the surface of the internal member using plasma at atmospheric pressure to form a coating composed of said ceramic crystal material comprising oxygen at a molar ratio of 1.5 times or more to yttrium and fluorine at a molar ratio of 1.4 times or more to yttrium as an average, wherein the yttrium oxyfluoride comprises at least one of Y2O3, YF3, YOF, and Y5O4F7, and the ceramic crystal material comprises any one of YFCO3, YFSeO3, YFSO4, and YFMoO4. Claim 12 A method for manufacturing an internal component of a plasma treatment apparatus according to claim 11, wherein the element that becomes a +4 or +6 ion is at least one of C, Si, Ge, Zr, Hf, S, Cr, Se, Mo, Te, and W. Claim 13 delete Claim 14 delete Claim 15 delete

Images