Structural members

Abstract

To provide a structural component with a highly durable protective film against plasma. [Solution] The structural member 10 comprises a base material 100 and a protective film 200 that covers the surface 110 of the base material 100 and mainly contains yttria. When the surface 210 of the protective film 200 is analyzed using X-ray diffraction and the diffraction pattern obtained is determined, the particle diameter calculated based on the waveform of the peaks attributed to the (222) plane of the cubic crystal is D1, and the particle diameter calculated based on the waveform of the peaks attributed to the (622) plane of the cubic crystal is D2, the average value of D1 and D2 in this structural member 10 is 90 Å or more.

Description

[Technical Field]

[0001] This invention relates to a structural member. [Background technology]

[0002] Components of semiconductor manufacturing equipment, such as the inner walls of chambers, require durability against plasma. Therefore, it is common practice to use structural components with a protective film formed on the surface of a substrate, as described in Patent Document 1 below. For the protective film, materials such as yttria are often used. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2007-321183 [Overview of the project] [Problems that the invention aims to solve]

[0004] In semiconductor manufacturing equipment, repeated processing of substrates gradually degrades the protective film over time. To reduce the frequency of maintenance on semiconductor manufacturing equipment, it is desirable to have the highest possible durability of the protective film against plasma.

[0005] This invention has been made in view of these problems, and its objective is to provide a structural member with a protective film that has high durability against plasma. [Means for solving the problem]

[0006] To solve the above problems, the structural member according to the present invention comprises a base material and a protective film covering the surface of the base material, the protective film mainly composed of yttria. When the surface of the protective film is analyzed using X-ray diffraction and the diffraction pattern obtained is determined, D1 is the particle diameter calculated based on the waveform of the peaks attributed to the (222) plane of the cubic crystal, and D2 is the particle diameter calculated based on the waveform of the peaks attributed to the (622) plane of the cubic crystal, the average value of D1 and D2 in this structural member is 90 Å or more.

[0007] Experiments conducted by the present inventors confirmed that the durability of a protective film against plasma can be sufficiently enhanced by forming a protective film mainly composed of yttria such that the average value of D1 and D2 is 90 Å or higher. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a structural member with a protective film that has high durability against plasma. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing a cross-section of a structural member. [Figure 2] This figure shows the relationship between the average particle diameter of the protective film and the durability of the protective film against plasma. [Figure 3] This is a diagram illustrating an analytical method using X-ray diffraction. [Figure 4] This is a diagram illustrating an analytical method using X-ray diffraction. [Figure 5] This is a diagram illustrating an analytical method using X-ray diffraction. [Figure 6] This is a diagram illustrating an analytical method using X-ray diffraction. [Figure 7] This table shows a list of film formation conditions and other factors used when forming a protective film. [Modes for carrying out the invention]

[0010] Hereinafter, this embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same reference numerals are used for the same components in each drawing as much as possible, and redundant descriptions are omitted.

[0011] The structural member 10 according to this embodiment is configured as a member for a semiconductor manufacturing apparatus such as a plasma etching apparatus. Specifically, the structural member 10 is a member used as the inner wall of a processing chamber included in a semiconductor manufacturing apparatus. Note that the use of such a structural member 10 is merely an example. The structural member 10 may be a member disposed inside a processing chamber included in a semiconductor manufacturing apparatus, such as a focus ring.

[0012] As shown in FIG. 1, the structural member 10 includes a base material 100 and a protective film 200. In a plasma etching apparatus or the like, the surface 210 of the protective film 200 is exposed toward the space inside the processing chamber. The protective film 200 is provided for the purpose of protecting the surface 110 of the base material 100 from plasma.

[0013] The base material 100 is a member that generally occupies the entire structural member 10. In this embodiment, the base material 100 is a ceramic sintered body mainly containing high-purity alumina (Al2O3), but it may be a different type of ceramics or a member other than ceramics (for example, a metal member). Further, the surface 110 of the base material 100 is a flat surface in this embodiment, but it may be a curved surface or the like. Also, a slope may be provided on a part of the surface 110.

[0014] As mentioned above, the protective film 200 is a film formed to protect the substrate 100 from plasma. The protective film 200 is formed to cover the entire surface 110 of the substrate 100. The protective film 200 is made of a material mainly composed of yttria (Y2O3). The ratio of the number of yttrium (Y) atoms and oxygen (O) atoms in the protective film 200 may differ from that described above. In this embodiment, the protective film 200 is a film formed using physical vapor deposition (PVD), but it may also be a film formed using other film formation methods.

[0015] In this specification, "major component" refers to the compound that is present in the greatest quantity in the object (e.g., protective film 200). Specifically, "major component" refers to a compound that, when quantitative or semi-quantitative analysis is performed on the object using X-ray diffraction (XRD), is found to be present in a relatively greater quantity by volume or mass ratio than any other compound in the object.

[0016] In the protective film 200 of this embodiment, the proportion of the main component (yttria) is greater than 50% by volume or mass. This proportion may be greater than 70%, greater than 90%, or even 100%.

[0017] The thickness of the protective film 200 is set appropriately according to the length of time for which durability must be maintained. In this embodiment, the thickness of the protective film 200 is 15 μm or less.

[0018] The inventors have decided to use yttria as the material for the protective film 200, as in this embodiment, and have been investigating ways to further improve the plasma resistance of the material. As a result, it has been confirmed that when the protective film 200 is formed using a material mainly composed of yttria, the plasma resistance of the protective film 200 changes depending on the crystal structure of the protective film 200. Specifically, when the diffraction pattern obtained by analyzing the surface 210 using X-ray diffraction is analyzed, and the particle diameter calculated based on the waveform of the peak attributed to the (222) plane of the cubic crystal is defined as "particle diameter D1", the particle diameter calculated based on the waveform of the peak attributed to the (622) plane of the cubic crystal is defined as "particle diameter D2", and the average value of particle diameter D1 and particle diameter D2 is defined as "average particle diameter", it has been confirmed that the larger the average particle diameter, the higher the plasma resistance of the protective film 200. The specific methods for calculating each of the above "particle diameters" will be explained later.

[0019] The inventors prepared multiple samples of structural members 10 with different crystal structures in the protective film 200, and then evaluated the durability of each protective film 200 against plasma. To evaluate the durability of the protective film 200 against plasma, the surface 210 of each protective film 200 was exposed to a plasma atmosphere using an inductively coupled reactive ion etching (ICP-RIE) apparatus (not shown). The exposure of the surface 210 to the plasma atmosphere was carried out using the following method.

[0020] First, a 4-inch silicon wafer was held in the chamber of an inductively coupled reactive ion etching apparatus using an electrostatic chuck. A sample of the structural component 10 to be evaluated was placed on the silicon wafer. Subsequently, plasma was generated in the chamber to expose the surface 210 of the protective film 200 to a plasma atmosphere. SF6 was used as the process gas and supplied to the chamber at a flow rate of 100 sccm. The pressure inside the chamber was adjusted to 0.5 Pa. The exposure time was 60 minutes. The power output was set to 1500W for the ICP coil output and the bias output was turned OFF (i.e., 0W). Under these conditions, the test in which the surface 210 of the protective film 200 is exposed to a plasma atmosphere will be referred to as the "standard plasma test" below. In the standard plasma test, as described above, the bias output was turned OFF, so the plasma was not drawn towards the protective film 200 and was hardly used for etching the protective film 200. The surface 210 of the protective film 200 is simply exposed to a non-directional plasma.

[0021] Figure 2 shows the results of the standard plasma test performed on each of the multiple structural members 10. The horizontal axis of the graph in Figure 2 represents the average particle diameter mentioned earlier. The vertical axis represents the fluorination amount of the protective film 200 after the standard plasma test. "Fluorination amount" is an indicator of how much fluorine atoms, which are part of the plasma, have penetrated into the interior of the protective film 200. The specific method for calculating the fluorination amount is as follows.

[0022] First, the surface 210 of the protective film 200, which had undergone a standard plasma test, was sputtered with argon, and the amount of fluorine atoms present on the surface 210 was continuously measured using X-ray photoelectron spectroscopy (XPS). The measurement was performed over 145 seconds. At each time point, the percentage (in units: %) of the argon measurement was calculated, and the cumulative value of the obtained values ​​was calculated as the "fluorination amount" of the sample. The higher the durability of the protective film 200 against plasma, the smaller the fluorination amount calculated as described above. The fluorination amount can be used as an indicator of the durability of the protective film 200 against plasma.

[0023] As is clear from Figure 2, the amount of fluoride in the protective film 200 generally decreases as the average particle diameter of the protective film 200 increases. For protective films 200 with an average particle diameter of 90 Å or more, the amount of fluoride was reduced to approximately 2500, confirming that they possess sufficient durability against plasma.

[0024] The method for calculating the average particle diameter is explained below. The average particle diameter is calculated based on the results of analyzing the crystal structure of protective film 200 using X-ray diffraction.

[0025] For each sample, the average particle diameter of the protective film 200 was measured using the following method. First, grazing-incidence X-ray diffraction (GIXRD) was performed on the protective film 200 formed on the substrate 100 using out-of-plane measurement.

[0026] X-ray diffraction was performed using an X-ray diffractometer XRD, as shown in Figure 3. In the X-ray diffractometer XRD, X-rays of a specific wavelength generated by an X-ray generator XR are incident on the surface 210 of the protective film 200, which is the object of measurement. The intensity distribution obtained by detecting the scattered light generated on the surface 210 with a detector DT is called the diffraction angle θ. B The intensity distribution (diffraction pattern) of the scattered light for each X-ray corresponds to the crystal structure of the protective film 200. At this time, the incident angle θ of the X-rays on the surface 210 isA The larger the angle of incidence θ, the more the resulting diffraction pattern corresponds to the crystal structure at a depth from the surface 210. A By performing X-ray diffraction while varying the coefficient, the crystal structure of the protective film 200 at any desired depth can be investigated.

[0027] In this embodiment, a Rigaku Smart Lab X-ray diffractometer (XRD) was used. The tube voltage was set to 45kV, the tube current to 200mA, the scan range to 18-80°, the step to 0.05°, the scan speed to 0.5° / min, and the incident angle of the X-rays θ A The angle was set to 0.3°. The sample size was approximately 20mm x 20mm.

[0028] Line L10 in Figure 4 is an example of a diffraction pattern obtained by analyzing the protective film 200 using the X-ray diffraction method described above. This diffraction pattern will also be referred to as the "measured diffraction pattern L10" below. Multiple peaks appear in the measured diffraction pattern L10, and the waveform of each peak is unique to the material and crystal structure of the protective film 200. For example, the diffraction angle θ corresponding to the maximum value of each peak B This value corresponds to the crystal structure of protective film 200. Furthermore, the height of each peak corresponds to the diffraction angle θ. B The height corresponds to the proportion of the surface 210 of the protective film 200 occupied by the corresponding crystal structure.

[0029] The dashed-dotted line L0 shown in Figure 4 represents the background intensity when no peaks appear. The waveform of the dashed-dotted line L0 can be estimated and obtained, for example, from the overall waveform of the diffraction pattern.

[0030] The line L11 shown in Figure 5 has a diffraction angle θ of 20.72 degrees relative to the background shown by the dashed line L0 in Figure 4. B This represents a hypothetical diffraction pattern when only the peaks with the maximum values ​​are added together. The same applies to lines L12 to L22 shown in Figure 5, where each has a specific diffraction angle θ relative to the background.B It represents a provisional diffraction pattern when only the peaks that are the maximum in

[0031] The diffraction angle θ corresponding to the peak of line L12 B is 29.23 degrees, and the diffraction angle θ corresponding to the peak of line L13 B is 33.89 degrees, and the diffraction angle θ corresponding to the peak of line L14 B is 41.70 degrees, and the diffraction angle θ corresponding to the peak of line L15 B is 43.50 degrees, and the diffraction angle θ corresponding to the peak of line L16 B is 48.41 degrees, and the diffraction angle θ corresponding to the peak of line L17 B is 56.10 degrees, and the diffraction angle θ corresponding to the peak of line L18 B is 56.70 degrees, and the diffraction angle θ corresponding to the peak of line L19 B is 57.54 degrees, and the diffraction angle θ corresponding to the peak of line L20 B is 58.83 degrees, and the diffraction angle θ corresponding to the peak of line L21 [[ID=​​​​​​​​​​​​By individually adjusting values ​​such as the height of the peak relative to the background, the waveform of the approximate diffraction pattern L30 is brought closer to the measured diffraction pattern L10. When the waveforms of both patterns roughly match as a result of this process, each of the provisional diffraction patterns shown by lines L11 to L22 will have a diffraction angle θ of the measured diffraction pattern L10. B This corresponds to waveforms decomposed into individual waveforms. This process can be performed manually while observing waveforms such as the approximate diffraction pattern L30, but it can also be performed automatically using software functions.

[0034] If the material of the protective film 200 is yttria, the diffraction angle θ of the peak attributed to the (222) plane of the cubic crystal is B It is known that this is approximately 29.15 degrees. Therefore, in the example shown in Figure 5, the peak attributed to the (222) plane of the cubic crystal can be inferred to be the peak of line L12.

[0035] If the material of the protective film 200 is yttria, the diffraction angle θ of the peak attributed to the (622) plane of the cubic crystal is B It is known that this is approximately 57.62 degrees. Therefore, in the example shown in Figure 5, the peak attributed to the (622) plane of the cubic crystal can be inferred to be the peak of line L19.

[0036] The "LN" shown in Figure 6 is obtained by extracting one of the peaks from line L12, etc., and transforming it so that the dashed-dotted line L0, which represents the background, becomes a flat line. The "α" in the same figure is the diffraction angle θ at which the peak is maximized. B This is the value multiplied by 1 / 2. "β" is the so-called "full width at half maximum" of the peak. That is, when the maximum value of the peak is P, the width of the peak at a height of P / 2 is given by the diffraction angle θ. B This is expressed as the range of values. The waveform shown by line LN, and the corresponding α and β values ​​for that waveform, can be obtained for each of the lines L12 and L19, etc.

[0037] Scherrer's equation is known as a means of calculating the particle diameter (D) of the crystal structure corresponding to each peak, from the waveform of each peak indicated by line L12, etc. Scherrer's equation is expressed by the following equation (1).

number

[0038] The "K" on the right-hand side of equation (1) is the Scherrer constant, which represents the shape factor, and in this embodiment, 0.94 is used. "λ" represents the wavelength of the X-rays irradiated onto surface 210 in units of "Å", and in this embodiment, 1.5418 (Å) is used. "α" and "β" are the same "α" and "β" that were explained with reference to Figure 6. The unit of β is "degree".

[0039] For example, by calculating "α" and "β" shown in Figure 6 for the waveform of the peak of line L12, the particle diameter (D) can be calculated using these values ​​and equation (1). The particle diameter calculated in this way can be said to be the particle diameter calculated based on the waveform of the peak belonging to the (222) plane of the cubic crystal. This particle diameter will also be referred to as "particle diameter D1" below.

[0040] Similarly, the values ​​"α" and "β" shown in Figure 6 can be calculated for the waveform of the peak of line L19, and the particle diameter (D) can be calculated using these values ​​and equation (1). The particle diameter calculated in this way can be said to be the particle diameter calculated based on the waveform of the peak belonging to the (622) plane of the cubic crystal. This particle diameter will also be referred to as "particle diameter D2" below.

[0041] The "average particle diameter" shown in Figure 2 is the average value of particle diameter D1 and particle diameter D2 calculated as described above. As mentioned earlier, for protective films 200 with an average particle diameter of 90 Å or more, the fluoride amount was reduced to approximately 2500, confirming that they have sufficient durability against plasma. In other words, by forming the protective film 200 so that the average particle diameter is 90 Å or more, a protective film 200 with high plasma durability can be obtained.

[0042] Note that the waveform examples shown in Figures 4, 5, and 6 are examples used to explain the definition and calculation method of average particle diameter, and do not correspond to the protective film 200 according to this embodiment.

[0043] The manufacturing methods for each sample used to obtain the data in Figure 2 will be explained with reference to Figure 7. In the same figure, the sample shown as "No. 1" is a sample prepared under conditions such that the average particle diameter on the surface 210 of the protective film 200 is 92.5 Å. "No. 2" is a sample prepared under conditions such that the average particle diameter on the surface 210 of the protective film 200 is 111 Å, "No. 3" is a sample prepared under conditions such that the average particle diameter on the surface 210 of the protective film 200 is 112.5 Å, "No. 4" is a sample prepared under conditions such that the average particle diameter on the surface 210 of the protective film 200 is 135 Å, and "No. 5" is a sample prepared under conditions such that the average particle diameter on the surface 210 of the protective film 200 is 56 Å.

[0044] In the table in Figure 7, the "Substrate" column shows the composition of the surface 110 of the substrate 100, which is alumina. In samples No. 1 to 3, the surface 110 of the substrate 100 is polycrystalline. In sample No. 4, the surface 110 of the substrate 100 is monocrystalline. In sample No. 5, the surface 110 of the substrate 100 is amorphous.

[0045] The protective films 200 for samples No. 1 to 5 were all formed using physical vapor deposition (PVD). In the table in Figure 7, the "Pressure" column shows the pressure inside the deposition chamber during the formation of the protective film 200, specifically the argon pressure, expressed in units of "Pa".

[0046] In the table in Figure 7, the "Sa" column shows the arithmetic mean height (Sa) of the surface 110 immediately before the protective film 200 is formed, expressed in units of "μm".

[0047] As shown in Figure 7, each of the samples from No. 1 to 5 differs from the others in the composition of the surface 110 of the substrate 100, the arithmetic mean height, and the deposition conditions of the protective film 200 (specifically, the pressure in the deposition chamber). As a result, the average particle diameter of the protective film 200 also differs from the others.

[0048] For each of the samples No. 1 to 5, the particle diameter D1, particle diameter D2, and average particle diameter were calculated. The obtained values ​​are shown in Figure 7. Subsequently, a standard plasma test was performed on each sample, and the results shown in Figure 2 were obtained. As described with reference to Figure 2, for each of the samples No. 1 to 4, where the average particle diameter of the protective film 200 was 90 Å or more, the fluoride amount was less than 2500, confirming that the protective film 200 has sufficiently high durability against plasma. For each of the samples No. 5, where the average particle diameter of the protective film 200 was less than 90 Å, the fluoride amount exceeded 3000, confirming that the protective film 200 does not have sufficient durability against plasma.

[0049] Furthermore, the inventors have confirmed that even if the average particle diameter of the protective film 200 is 90 Å or more, if either particle diameter D1 or particle diameter D2 is less than 50 Å, the protective film 200 may not have sufficient durability against plasma. Therefore, it is preferable to form the protective film 200 such that the smaller of particle diameter D1 and particle diameter D2 is 50 Å or more.

[0050] The embodiments have been described above with reference to specific examples. However, this disclosure is not limited to these specific examples. Modifications made to these specific examples by those skilled in the art are also included within the scope of this disclosure, as long as they retain the features of this disclosure. The elements, their arrangement, conditions, shapes, etc., of each of the aforementioned specific examples are not limited to those illustrated and can be modified as appropriate. The elements of each of the aforementioned specific examples can be combined in different ways as appropriate, as long as no technical inconsistencies arise. [Explanation of Symbols]

[0051] 10: Structural members 100: Base material 110: Surface 200: Protective film 210: Surface D1,D2: Particle diameter

Claims

1. Substrate and A protective film comprising a film covering the surface of the substrate, the protective film mainly containing yttria, In the diffraction pattern obtained by analyzing the surface of the protective film using X-ray diffraction, Let D1 be the particle diameter calculated based on the waveform of the peaks attributed to the (222) plane of the cubic crystal. When D2 is the particle diameter calculated based on the waveform of the peaks attributed to the (622) plane of the cubic crystal, A structural member characterized in that the average value of D1 and D2 is 90 Å or more.

2. The structural member according to claim 1, characterized in that the smaller of D1 and D2 is 50 Å or more.

3. The structural member according to claim 1, characterized in that the protective film is a film formed using a physical vapor deposition method.

4. The structural member according to claim 1, characterized in that the base material contains alumina as the main component.

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