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 covering the surface 110 of the base material 100. The protective film 200 mainly contains yttria, and in the Raman spectrum of the protective film 200 obtained by Raman spectroscopy, 370 cm⁻¹ -1 The half-width of the peak at nearby wavenumbers is 23 cm. -1 That's all.

Description

[Technical Field]

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

[0002] Structural members having a protective film on the surface of a substrate are used in various fields such as semiconductor manufacturing equipment. For example, as described in Patent Document 1 below, in semiconductor manufacturing equipment, a protective film is formed on the surface of the substrate constituting the inner wall of the chamber to protect the substrate from plasma. Such protective films can be made of oxide ceramics such as yttria. [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 for the protective film to have as high a durability against plasma as possible.

[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 contains yttria, and in the Raman spectrum of the protective film obtained by Raman spectroscopy, 370 cm⁻¹ -1 The half-width of the peak at nearby wavenumbers is 23 cm.-1 That's all.

[0007] Experiments conducted by the inventors have revealed a new finding: the more irregular the atomic arrangement of the protective film, the higher its durability against plasma. The above half-width is 23 cm. -1 When the atomic arrangement is as irregular as described above, degradation of the protective film is less likely to progress from the surface to the interior, and as a result, the durability of the protective film is thought to improve. [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 figure schematically shows a cross-section of the structural member according to this embodiment. [Figure 2] This is a diagram used to explain Raman spectra. [Figure 3] This is a diagram used to explain Raman spectra. [Figure 4] This table shows a list of film formation conditions and peak widths at half maximum in the Raman spectrum when forming a protective film. [Figure 5] This figure shows the relationship between the full width at half maximum (FMAX) of the peak in the Raman spectrum and the durability of the protective film against plasma. [Modes for carrying out the invention]

[0010] This embodiment will be described below with reference to the attached drawings. To facilitate understanding of the explanation, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations are omitted.

[0011] The structural member 10 according to this embodiment is configured as a component for semiconductor manufacturing equipment, such as a plasma etching apparatus. Specifically, the structural member 10 is a component used as the inner wall of a processing chamber in semiconductor manufacturing equipment. However, this application of the structural member 10 is merely an example. The structural member 10 may also be a component placed inside the processing chamber of semiconductor manufacturing equipment, such as a focus ring.

[0012] As shown in Figure 1, the structural member 10 comprises a base material 100 and a protective film 200. In a plasma etching apparatus, the surface 210 of the protective film 200 is exposed to 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 component that occupies almost the entirety of the structural member 10. In this embodiment, the base material 100 is a ceramic sintered body mainly composed of high-purity alumina (Al2O3), but it may be a different type of ceramic, or a component other than ceramic (for example, a metal component). Also, 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. Furthermore, a slope may be provided on a part of the surface 110.

[0014] As mentioned earlier, 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. Specifically, the yttria referred to above is Y2O3. The ratio of the number of yttrium (Y) atoms to the number of 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, the "main component" refers to the compound most contained in the object (here, the protective film 200). Specifically, the "main component" is a compound that, when quantitative analysis or semi-quantitative analysis using X-ray Diffraction (XRD) is performed on the object, is confirmed to be relatively more contained in terms of volume ratio or mass ratio than any other compound contained in the object.

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

[0017] The thickness of the protective film 200 is appropriately set according to the length of the period for which durability is required, etc. In the present embodiment, the thickness of the protective film 200 is 20 μm or less.

[0018] The inventors of the present invention decided to use yttria as in the present embodiment as the material of the protective film 200, and have been further studying how to further enhance the durability of the material against plasma. As a result, it was confirmed that there is a correlation between the waveform of the Raman spectrum of the protective film 200 obtained by Raman spectroscopy and the durability of the protective film 200 against plasma.

[0019] The Raman spectrum of the protective film 200 was obtained by the following method. As the measuring device, a laser Raman microscope (RAMAN Imager2) manufactured by Nanophoton was used. Using this device, light with a wavelength of 532 nm was incident on the surface 210 of the protective film 200 for 60 seconds, and the generated Raman scattered light (Stokes light) was detected and analyzed to obtain the Raman spectrum. The irradiation of light on the surface 210 for 60 seconds was performed a total of 5 times, and the average of the respective Raman spectra obtained each time was obtained as the final Raman spectrum.

[0020] Line L10 in Figure 2(A) is an example of an acquired Raman spectrum. The horizontal axis in the figure represents the reciprocal of the wavelength of the detected Raman scattered light, i.e., the wavenumber, and its unit is "cm". -1 The vertical axis represents the intensity distribution of Raman scattered light at each wavenumber. Note that in this embodiment, when the protective film 200 is yttria, the value is 370 cm². -1 A large peak appears in the nearby wavenumber range. Therefore, to include this peak, the wavenumber should be set to 140 cm. -1 From 640cm -1 Data was acquired within the specified range.

[0021] The dashed line L0 shown in Figure 2(A) represents the background intensity, i.e., the baseline waveform, when no peaks appear. This waveform can be inferred and obtained, for example, from the overall waveform of the Raman spectrum shown by line L10.

[0022] Line L11 in Figure 2(B) is obtained by applying a transformation process to the Raman spectrum waveform of line L10 so that the baseline, the dashed-dotted line L0, becomes flat. Line L11 can also be described as the waveform obtained by subtracting each value of the dashed-dotted line L0 from each value of line L10. This type of transformation process is also called "baseline correction" and is often pre-implemented as a standard function in software.

[0023] As shown in Figure 2(B), in the waveform of line L11 obtained by baseline correction, 370 cm² -1 A relatively large peak appears in the vicinity of the wavenumber. When the waveform of line L11 is fitted so that only this peak exists and the waveform is smooth, the waveform shown by line L12 in Figure 3 is obtained. For such fitting, known methods such as Gaussian fitting can be used.

[0024] When the maximum height at the peak of the line L12 is defined as "H", the width of the peak at the height of H / 2, that is, the so-called "half-value width", is hereinafter also referred to as "half-value width W". Such a half-value width W can be the half-value width of the peak at a frequency near 370 cm -1 in the Raman spectrum of the protective film 200 obtained by Raman spectroscopy.

[0025] The inventors prepared a plurality of samples of the structural member 10 and, for each protective film 200, measured the half-value width W as described above and evaluated the durability of the protective film 200 against plasma. A total of 7 samples of the structural member 10 were prepared, numbered from No. 1 to No. 7. The protective film 200 was formed on each sample using the physical vapor deposition method. A list of the evaluation results and the like is shown in the table of FIG. 4.

[0026] The "pressure" shown in FIG. 4 represents the pressure in the film-forming chamber during the formation of the protective film 200, specifically, the pressure of argon, expressed in the unit of "Pa".

[0027] The "hardness" shown in Figure 4 represents the indentation hardness of the protective film 200, expressed in units of "GPa". The indentation hardness of the protective film 200 was measured by performing a nanoindentation test on the surface 210 of the protective film 200 formed on the substrate 100. A Berkovich indenter was used, and the indentation depth was fixed at 200 nm. The indentation hardness (indentation hardness) was measured at multiple locations on the surface 210. Each measurement location was a part of the surface 210 that was free of scratches and dents. If the surface 210 is polished and smoothed prior to the measurement of indentation hardness, a more accurate measurement of indentation hardness can be obtained. The number of measurement locations was set to at least 10, and the average value of the indentation hardness measured at each location was calculated as the indentation hardness value of the protective film 200. For other specific test methods, analytical methods, procedures for verifying the performance of test equipment, and requirements for standard reference samples, we followed the methods specified in ISO 14577.

[0028] The "full width at half maximum" shown in Figure 4 is the value of the full width at half maximum W mentioned earlier. Raman spectra were acquired and the full width at half maximum W was calculated three times for each sample. The full width at half maximum values ​​for each sample shown in Figure 4 are obtained by averaging the full width at half maximum W calculated three times.

[0029] After obtaining the indentation hardness and full width at half maximum (FWHM) W of the protective film 200, each sample was subjected to a plasma durability evaluation test. To evaluate the durability of the protective film 200, 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 conditions used for exposing the surface 210 to the plasma atmosphere are as follows.

[0030] First, a 4-inch silicon wafer was held in place by an electrostatic chuck inside the chamber of an inductively coupled reactive ion etching apparatus. Next, a sample of the structural component 10 to be evaluated was placed on the silicon wafer. Subsequently, plasma was generated inside the chamber to expose the surface 210 of the protective film 200 to the plasma atmosphere. SF6 was used as the process gas and supplied into the chamber at a flow rate of 100 sccm. The pressure inside the chamber was adjusted to 0.5 Pa. The exposure time was 30 minutes. The power output was set to 1500W for the ICP coil output and 750W for the bias output. By setting the bias output to 750W, the plasma was drawn towards the protective film 200 and subjected to etching of the protective film 200.

[0031] The "fluoride content" shown in Figure 4 is an indicator of how much fluorine atoms penetrated into the protective film 200 when it was exposed to a plasma atmosphere as described above. The specific method for calculating the fluoride content is as follows.

[0032] First, the surface 210 of the protective film 200, exposed to a plasma atmosphere as described above, 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.

[0033] The relationship between the full width at half maximum (FWHM) W and the amount of fluoride is plotted in a graph, as shown in Figure 5. As shown in the figure, it was confirmed that the amount of fluoride in the protective film 200 decreases as the FWHM W increases. In other words, it was confirmed that the durability of the protective film 200 against plasma increases as the FWHM W increases. FWHM W is 23 cm-1 In the samples described above, the amount of fluoride is sufficiently small, indicating that the material has sufficient resistance to plasma.

[0034] The more irregular the atomic arrangement of the protective film 200, the larger the value of the full width at half maximum (FWHM) W. A FWHM W of 23 cm² is obtained. -1 When the atomic arrangement is as irregular as described above, degradation of the protective film 200 is less likely to progress from the surface to the inner layers, and as a result, the durability of the protective film 200 is considered to be improved.

[0035] As shown in Figure 4, the half-width W is 23 cm. -1 In all of the samples (No. 3-7) described above, it was confirmed that the indentation hardness of protective film 200 was 12 GPa or higher.

[0036] 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]

[0037] 10: Structural members 100: Base material 110: Surface 200: Protective film

Claims

1. Substrate and The substrate comprises a protective film covering the surface of the substrate, The protective film contains yttria as its main component, In the Raman spectrum of the protective film obtained by Raman spectroscopy, 370 cm⁻¹ －１ The peak width at half maximum in the vicinity of wavenumber is 23 cm. －１ A structural member characterized by the above.

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

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

4. The structural member according to claim 1, characterized in that the indentation hardness of the protective film is 12 GPa or more.

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