Opaque quartz glass with high absorption in infrared range

Abstract

The invention relates to opaque quartz glass with high absorption in the near-infrared range and a production method thereof. The invention also relates to the use of the opaque quartz glass according to the invention or of the opaque quartz glass obtained from the method according to the invention in a processing chamber in which semiconductor wafers are processed.

Description

Opaque quartz glass with high absorption in the infrared range Technical Field

[0001] This invention relates to an opaque quartz glass with high absorption in the infrared wavelength range of 1µm to 10µm and a method for producing the same. The invention also relates to the use of the opaque quartz glass according to the invention, or the opaque quartz glass obtained from the method according to the invention, in a processing chamber in which semiconductor wafers are processed. Background Technology

[0002] Various devices, such as reactors, equipment, support plates, bell jars, crucibles, protective shields, or simpler components (such as tubes, rods, plates, flanges, rings, or blocks), are used in the production of semiconductor components and optical displays. These devices must meet high requirements in terms of purity, chemical and thermal stability, and mechanical strength. They can be made of, for example, stainless steel, but increasingly, quartz glass. This is because high-purity silica is inert to conventional semiconductor materials. Quartz glass is also characterized by its high chemical stability relative to many process media and its high resistance to thermal shock.

[0003] In processing chambers where semiconductor wafers are processed at high temperatures, some components are heated by radiation from lamps. To ensure rapid and efficient heat transfer, the materials used for this purpose must have high absorption, particularly in the near-infrared range, i.e., in the 1 μm to 3 μm range. Since the components must also have low thermal mass to enable rapid thermal cycling of heating and cooling, high absorption must be achieved even when the components are very thin or have small wall thicknesses. Because process control is difficult when the absorption of a material is highly temperature-dependent, it is advantageous for absorption to depend on temperature to the minimum possible extent. These (infrared) optical properties should be combined, as far as possible, with the proven properties of high-purity quartz glass for application in processing chambers used for wafer fabrication.

[0004] In addition, components made of other materials, high-purity silicon carbide (e.g., CVD-SiC), and high-purity Si are also used. However, the production and processing of these materials are significantly more complex and expensive than that of quartz glass.

[0005] Corresponding quartz glass materials are described, for example, in EP 3 068 739 A. The described material is a composite material comprising a matrix made of quartz glass, with silicon-containing regions embedded within the matrix. Although the composite material exhibits high absorption in the near-infrared at visible wavelengths up to 1 μm, the absorption decreases significantly at room temperature. Only at higher temperatures does the absorption increase for wavelengths greater than 1 μm, reaching a constant value from approximately 1000 °C. However, at lower temperatures, the infrared absorption is highly temperature-dependent, making process control difficult and therefore disadvantageous.

[0006] Another composite material for use in processing chambers for wafer fabrication is known from US 2001 / 025001 A. This composite material consists of quartz glass and a second phase made of silicon, silicon carbide, silicon nitride, titanium nitride, or titanium carbide. The object of this invention is to provide a material that is less prone to cracking and releases fewer particles during machining than quartz glass. Due to this production method, the composite material has an open porosity of less than 15% or less than 5%. Open-pore materials are very difficult to clean, especially with liquids or acids. During machining, impurities can penetrate into the open pore channels. It is practically impossible to remove these impurities without leaving residue. Furthermore, the optical properties of the resulting material are not described, and the material obtained from US 2001 / 025001 A contains carbon as long as silicon carbide is the second phase in the composite material. This is caused by the production method used: silicon carbide as the starting material always contains carbon as an impurity, and this is not removed in the described production method of vacuum sintering under pressure.

[0007] JP 2006 / 027930 A relates to a black quartz glass, wherein the black color is due to the incorporation of graphite particles. The quartz glass is produced by sintering from a mixture of amorphous quartz glass powder (fly ash) and graphite powder having a defined particle size distribution. The carbon particles used account for 0.05% to 2% by weight of SiO2 and have a diameter of 0.07 μm to 0.5 μm or 0.05 μm to 1 μm. In particular, milled quartz glass is used as the SiO2 powder, which is produced by flame hydrolysis in a hydrogen / oxygen flame. The resulting material is sintered at 1100 to 1500 °C. At excessively high temperatures, a decrease in the density of the quartz glass is observed due to bubble formation. The resulting quartz glass contains elemental carbon, which is disadvantageous for certain applications.

[0008] JPH05170477 A relates to a black quartz glass and a cell for optical analysis using the glass. The quartz glass is doped with 0.05 wt% to 0.3 wt% SiC (based on C concentration). Devitrification stability is improved by doping with nitrogen (10 ppm to 5000 ppm), fluorine (10 ppm to 5000 ppm), and chlorine (10 ppm to 1000 ppm). The transmittance is at most 1% with a layer thickness of 1 mm in the wavelength range of 200 nm to 25,000 nm. The resulting quartz glass is obtained by sintering at a temperature greater than or equal to 1700 °C in the absence of oxygen. At these temperatures, SiO2 is reduced by C to form SiC and CO. Further reaction between SiC and SiO2 forms SiO and CO. This produces gaseous carbon oxides, which form bubbles in the resulting material. Sintering is preferably performed under pressure to compress and keep the bubbles small. The resulting material is black, which can be attributed to impurities and / or carbon. The SiC particles used have a particle size in the range of 0.1 μm to 1 μm, which renders absorption in the near-infrared region ineffective.

[0009] US 5,674,792 relates to a method for preparing an opaque quartz glass material from a slurry (slurry casting method); the described material contains only SiO2 particles and pores.

[0010] US 6,355,587 relates to the production of quartz glass products through a special manufacturing method and doping. The quartz glass products are produced by adding a small amount (0.005 wt% to 0.01 wt%) of silicon nitrite or silicon carbide, wherein the SiC particles added to the slurry break down and release gases during sintering at temperatures above 1400°C, causing multiple bubbles to be trapped within the formed glass. Therefore, the densely sintered final product no longer contains any SiC. The resulting product has a bubble density of approximately 80 bubbles / mm² to 120 bubbles / mm², with an average bubble size ≤20 μm. This glass product blocks infrared radiation and is particularly used as a heat shield.

[0011] JP H06 122533 describes a method for producing a composite material in which SiO2 is deposited as a micropowder by flame hydrolysis, followed by deposition of an organochlorosilane from the gas phase onto the SiO2 powder at at least 700°C, and then converted to SiC by heat treatment in a hydrogen atmosphere at the same temperature. Finally, compression is performed at at least 1700°C in a non-oxidizing atmosphere. The resulting composite material has silicon carbide particles of up to 20 nm in size, implying low absorption in the near-infrared. In the described method, sintering or melting is performed at at least 1700°C in a non-oxidizing atmosphere to compress the glass, but as stated in the disclosure itself, the quartz glass and silicon carbide react with each other above 1400°C to form a gas. On the other hand, the examples given in this disclosure show that at heat treatment below 1700°C, free carbon exists in the material, and silicon carbide has not yet been formed. Therefore, a high temperature of at least 1700°C is required so that carbon and SiO2 can react to form silicon carbide. However, CO is certainly produced at these temperatures, resulting in highly bubbly materials.

[0012] Both WO 2025 / 159866 A and US 2025 / 0236987 A disclose a component comprising a body having a composition containing a mixture of silicon carbide (SiC) particles suspended in crystalline quartz. A method for preparing the composition includes the step of suspending the silicon carbide particles in liquid quartz to form the composition. The product obtained by this preparation method is transparent quartz containing SiC particles and is therefore transparent to visible light in the visible wavelength range. The material described therein exhibits a variety of emissivities at different temperatures.

[0013] A known disadvantage of these composite materials from the prior art is that absorption in the near-infrared wavelengths (i.e., 1 μm to 3 μm) is low at room temperature and also largely temperature-dependent. Impurities, especially metal compounds, can enhance absorption in this range, but are undesirable in materials used for semiconductor applications. The proportion of elemental carbon, such as that found in the SiO2 / SiC composite material from US 2001 / 025001 A, is also disadvantageous. Summary of the Invention

[0014] Therefore, the object of the present invention is to provide a composite material that exhibits the highest possible absorption in the near-infrared (i.e., 1 μm to 3 μm) range, even at room temperature, and that the composite material also exhibits low temperature dependence on absorption. These (infrared) optical properties should be combined with the proven properties of high-purity quartz glass for application in processing chambers used for wafer fabrication. These desired properties are particularly selected from high purity, high temperature resistance, high thermal shock resistance, high chemical resistance, good electrical insulation, good mechanical strength, the possibility of residue-free cleaning (e.g., by ultrasonic cleaning and hydrofluoric acid (HF) cleaning), mechanical machinability, low particle release during the process, and low production costs compared to high-purity ceramics.

[0015] These objectives are achieved in the context of this invention by a composite material having a matrix made of quartz glass, into which regions containing silicon carbide phases are embedded.

[0016] Therefore, the object of the present invention is a composite material having a matrix made of quartz glass, and a region containing a silicon carbide phase embedded in the matrix.

[0017] According to the present invention, a composite material having a matrix made of quartz glass and having regions therein embedded with silicon carbide phases has been found to have high absorption in the near infrared (i.e., 1 μm to 3 μm) even at room temperature, and also has low temperature dependence absorption, and is therefore ideally suited for processing chambers for wafer fabrication.

[0018] Compared to the composite material made of SiO2 and silicon described in EP 3 068 739 A, the composite material according to the present invention has significantly higher absorption at wavelengths greater than 1 μm in the infrared range at temperatures below or equal to 1000 °C. Furthermore, the temperature dependence of the material's absorption in this wavelength range is far less than that of the equivalent composite material according to EP 3 068 739 A.

[0019] Compared to the composite material in US 2001 / 025001 A, the composite material according to the present invention is substantially carbon-free, which is preferred for its intended use.

[0020] The matrix of the composite material according to the invention is opaque, translucent, or transparent. Within the matrix, there are regions containing a very finely distributed phase of silicon carbide (SiC), referred to herein as the silicon carbide-containing phase.

[0021] These regions affect the overall heat absorption of the composite material according to the invention. This is primarily due to the properties of silicon carbide.

[0022] The composite material according to the invention has high absorption in the near-infrared (i.e., 1 μm to 3 μm), and therefore the material can be heated efficiently and rapidly even with small wall thicknesses.

[0023] The 3 mm thick disk of the composite material according to the present invention has an absorption of preferably greater than 40%, more preferably greater than 50% at 1500 nm.

[0024] Furthermore, the composite material according to the invention exhibits a small change in the absorptivity (or emissivity) of a 3 mm disk at a wavelength of 1.5 μm in NIR between room temperature (20°C) and 1000°C. The change in absorptivity (or emissivity) is preferably less than 0.3, more preferably less than 0.2, and particularly preferably less than 0.1. In this respect, the composite material according to the invention differs from the materials described in WO 2025 / 159866 A and US 2025 / 0236987 A mentioned above, in which the material exhibits a variety of emissivities at different temperatures.

[0025] The silicon carbide phase is very finely and uniformly distributed within the quartz glass matrix. Although it can be located directly on the surface of the composite material, a coating to prevent oxidation is not necessary. Otherwise, the coating would result in additional undesirable reflections at the interface with the composite material.

[0026] The weight percentage of the silicon carbide phase in the composite material according to the invention is preferably less than or equal to 10% by weight, more preferably less than or equal to 9% by weight, even more preferably less than or equal to 8% by weight, even more preferably less than or equal to 7% by weight, even more preferably less than or equal to 6% by weight, even more preferably less than or equal to 5% by weight, based on the matrix made of quartz glass in each case.

[0027] Due to the desired low porosity according to the invention, it is desirable that the weight percentage of the silicon carbide-containing phase in the composite material according to the invention be less than 5% by weight based on a matrix made of quartz glass, as will be further described below. Attached Figure Description

[0028] Figure 1 shows the hemispherical reflection in the visible range and the IR range of a 3 mm thick composite material containing silicon carbide phases with varying amounts of α-silicon carbide, without the silicon carbide phase.

[0029] Figure 2 shows the hemispherical reflection in the visible range and the IR range of a 3 mm thick composite material containing a silicon carbide phase but without a silicon carbide phase and containing silicon carbide phases with different amounts of β-silicon carbide.

[0030] Figure 3 shows the hemispherical transmission in the visible range and the hemispherical reflection in the IR range of a 3 mm thick composite material containing silicon carbide phases with varying amounts of α-silicon carbide but without the silicon carbide phase.

[0031] Figure 4 shows the hemispherical transmission in the visible range and the hemispherical reflection in the IR range of a 3 mm thick composite material containing silicon carbide phases with varying amounts of β-silicon carbide but without the silicon carbide phase.

[0032] Figure 5 shows the calculated hemispherical absorption in the visible range and the calculated hemispherical absorption in the IR range for a 3 mm thick composite material containing silicon carbide phases with varying amounts of α-silicon carbide, without the silicon carbide phase.

[0033] Figure 6 shows the calculated hemispherical absorption in the visible range and the calculated hemispherical absorption in the IR range for a 3 mm thick composite material containing a silicon carbide phase but not containing a silicon carbide phase and containing different amounts of β-silicon carbide.

[0034] Figure 7 shows the emissivity of the composite material according to the invention with 2.5 wt% α-silicon carbide at different temperatures of 500°C, 750°C and 1000°C at elevated temperatures.

[0035] Figure 8 shows a SEM image of a cross-sectional region of the composite material according to the invention, containing 2.5 wt% silicon carbide, sintered at 1390 °C for 5 hours. P represents pores, and SiC represents SiC particles embedded in a quartz glass matrix.

[0036] Figure 9 shows a SEM image of a cross-sectional region of the composite material according to the invention, containing 2.5 wt% silicon carbide, sintered at 1390 °C for 10 hours. P represents pores, and SiC represents SiC particles embedded in a quartz glass matrix.

[0037] Figure 10 shows the temperature behavior of the near-infrared absorption rate of a sample with 2.5 wt% silicon carbide at a wavelength of 1.5 μm. Detailed Implementation

[0038] The weight percentage of the silicon carbide phase in the composite material according to the invention is preferably greater than or equal to 0.1 wt%, more preferably greater than or equal to 0.25 wt%, even more preferably greater than or equal to 0.5 wt%, even more preferably greater than or equal to 1 wt%, even more preferably greater than or equal to 1.5 wt%, even more preferably greater than or equal to 2 wt%, even more preferably greater than or equal to 2.5 wt%, based on the matrix made of quartz glass in each case.

[0039] In embodiments of the invention, the weight percentage of the silicon carbide phase in the composite material according to the invention is preferably 0.1 wt% to 5 wt%, more preferably 0.25 wt% to 5 wt%, even more preferably 0.5 wt% to 5 wt%, even more preferably 1 wt% to 5 wt%, even more preferably 1.5 wt% to 5 wt%, even more preferably 2 wt% to 5 wt%, even more preferably 2.5 wt% to 5 wt%

[0040] The weight percentage of the silicon carbide phase in the composite material according to the invention is preferably 0.25% to 10% by weight, more preferably 0.5% to 9% by weight, even more preferably 1% to 8% by weight, even more preferably 1.5% to 7% by weight, even more preferably 2% to 6% by weight, even more preferably 2.5% to 5% by weight, based on the matrix made of quartz glass in each case.

[0041] The thermal absorption of the composite material according to the invention depends on the proportion of the silicon carbide phase. A higher proportion of this phase results in higher absorptivity and emissivity. Therefore, the weight proportion of the silicon carbide phase should preferably be higher than the minimum amount defined above. On the other hand, a high volume proportion of the silicon carbide phase may complicate the production of the composite material, and therefore the maximum amount given above represents a suitable upper limit. The silicon carbide phase is primarily responsible for absorption in the infrared wavelength range greater than 1 μm to 5 μm.

[0042] The matrix of the composite material according to the invention preferably consists of quartz glass having a hydroxyl content of up to 30 ppm by weight. Hydroxyl groups lead to a decrease in the viscosity of the quartz glass. Therefore, hydroxyl groups are detrimental to high dimensional stability under thermal stress, and thus the maximum amount mentioned above should preferably be observed.

[0043] The hydroxyl content of transparent quartz glass is typically determined using infrared transmission measurements. However, this method is not readily applicable to endothermic composites. Therefore, the hydroxyl content of the composite material is determined by emission measurements in the absorption wavelength region (at 2.72 μm) of hydroxyl groups in quartz glass, by comparison with a standard having a known hydroxyl content.

[0044] The matrix of the composite material according to the invention may consist of undoped or doped quartz glass. In the context of the invention, in addition to SiO2, the doped quartz glass may also contain other oxide, nitride, or carbide components in amounts of up to 1000 ppm.

[0045] The region containing the silicon carbide phase is preferably formed of particulate silicon carbide. In this case, the d90 value of the particle size distribution of the silicon carbide particles is preferably less than 100 μm, more preferably less than 75 μm, and even more preferably less than 50 μm.

[0046] In addition, the particle size distribution of silicon carbide particles d 50 The value is preferably greater than 0.1 μm, more preferably greater than 0.5 μm, even more preferably greater than 1 μm, and even more preferably greater than 2 μm.

[0047] In addition, the particle size distribution of silicon carbide particles d 50 The value is preferably less than 100 μm, more preferably less than 75 μm, even more preferably less than 50 μm, and even more preferably less than 25 μm.

[0048] This produces the d-size distribution of silicon carbide particles. 50 The value is preferably in the range of 0.1 μm to 100 μm, more preferably 0.5 μm to 75 μm, even more preferably 1 μm to 50 μm, and even more preferably 2 μm to 25 μm.

[0049] In the context of this invention, the average size of the silicon carbide particles is particularly preferably suited to the average particle size of the SiO2 matrix particles, so that no undesirable separation effect due to sedimentation occurs during the production of the composite material according to the invention.

[0050] Particle size distribution was measured by laser diffraction using a Mastersizer 3000 from Malvern.

[0051] In the composite material according to the invention, silicon carbide in the silicon carbide-containing phase can exist in any variant. In the context of the invention, it is preferred that the silicon carbide in the composite material according to the invention exists in α-SiC and / or β-SiC variants. Particularly preferred is that the silicon carbide in the composite material according to the invention exists in the α-SiC variant.

[0052] For the intended use of the composite material according to the invention, it is preferred that the composite material has high purity. Therefore, the maximum permissible impurities in the corresponding components of the composite material according to the invention are preferably subject to certain limitations, which will be described in more detail below.

[0053] Therefore, it is preferred that the silicon carbide phase contains preferably less than 50 ppm, more preferably less than 25 ppm, and even more preferably less than 10 ppm of metallic impurities, which are determined by glow discharge spectroscopy.

[0054] Further preferably, the matrix made of quartz glass contains preferably less than 100 ppm, more preferably less than 50 ppm, and even more preferably less than 25 ppm of metallic impurities, which are determined by inductively coupled plasma optical emission spectroscopy.

[0055] Further preferably, the composite material according to the invention contains preferably less than 100 ppm, more preferably less than 50 ppm, and even more preferably less than 25 ppm of metallic impurities, which are determined by inductively coupled plasma optical emission spectroscopy.

[0056] Metallic impurities include alkali metals, alkaline earth metals, transition metals, and other metals classified in the periodic table.

[0057] A low cristobalite content of 1% or less in the matrix ensures a low tendency for devitrification and thus a low risk of cracking during operation.

[0058] In the context of this invention, iron and copper should be avoided as metallic impurities.

[0059] Furthermore, and particularly preferably, the composite material according to the invention has a carbon content of less than 0.1% by weight, more preferably less than 0.075% by weight, and even more preferably less than 0.05% by weight, based on the total weight of the composite material in each case. Specifically, the composite material according to the invention is carbon-free.

[0060] The carbon content here refers to the content of elemental carbon, and does not include the amount of carbon in the silicon carbide phase.

[0061] The low carbon content in the composite material according to the invention is achieved by the production method described below. During the production process of the composite material according to the invention, the composite material is sintered at high temperature in an air atmosphere, i.e., in the presence of oxygen, thereby resulting in a low carbon content.

[0062] For the intended use of the composite material according to the invention, it is preferred that the composite material has a low porosity.

[0063] Therefore, it is preferred that the composite material according to the invention has a porosity of less than 8%, more preferably less than 6%, and even more preferably less than 5%, which is defined as the pore volume based on the total volume of the composite material.

[0064] Specifically, preferably, the composite material according to the present invention does not have open-pore porosity.

[0065] The large pores in the composite material according to the invention can contribute to undesirable diffuse reflection. The low porosity of the composite material of the invention limits this effect. Furthermore, the matrix preferably contains small pores with a maximum pore size of less than 50 μm. The pores are primarily formed between sintered SiO2 particles and generally have a non-circular shape.

[0066] The low porosity and small pore size achieved by the composite material according to the invention also bring further technical advantages, such as high strength, high etch resistance (e.g., during wet etching with HF (an acid commonly used to clean quartz glass components)) and low roughness of mechanically polished surfaces.

[0067] Due to the low porosity and associated low diffuse reflection of the quartz glass matrix, visible and infrared radiation can penetrate deeply into the matrix and thus reach deeper absorption centers composed of the silicon carbide phase. This contributes to greater absorption.

[0068] Microscopic images and dye penetration tests show that the composite material according to the present invention has no open-cell porosity. The residual pores remaining after sintering are closed-cell.

[0069] Due to this preferred porosity according to the invention, the resulting composite material can be cleaned without leaving any residue. For this purpose, ultrasonic cleaning or cleaning with hydrofluoric acid (HF) is suitable, for example.

[0070] The composite material according to the invention has a reflectance value of preferably 10 to 150, more preferably 20 to 100, and even more preferably 25 to 90. In the context of the invention, the reflectance value (Y value in the Yxy color space) is measured using a Chroma Meter CR-410 colorimeter from Konica Minolta.

[0071] The composite material according to the invention has an L* value (perceived brightness) in the L*a*b* color space, preferably 20 to 200, more preferably 30 to 150, and even more preferably 40 to 100.

[0072] The composite material according to the invention has a hemispherical transmittance of less than 10%, more preferably less than 9%, more preferably less than 8%, more preferably less than 7%, more preferably less than 6%, more preferably less than 5%, more preferably less than 4%, more preferably less than 3%, more preferably less than 2%, more preferably less than 1%, and even more preferably less than 0.6% in the wavelength range of 400 nm to 2500 nm, thus making the composite material according to the invention particularly advantageous for the intended use described below. Transmission is measured using a spectrometer (grating spectrometer), with an integrating sphere used to integrate the reflected and transmitted radiation, thereby enabling the measurement of hemispherical reflection and transmission. Unlike the present invention, the materials described in WO 2025 / 159866 A and US 2025 / 0236987 A are transparent.

[0073] The composite material according to the invention has a 3 mm thick disk made of the composite material, which in various cases has a hemispherical reflection of preferably less than 60%, more preferably less than 50% at a wavelength of 1500 nm.

[0074] The 3mm disk of the composite material according to the invention exhibits an absorptivity / emissivity change of less than 0.3, more preferably less than 0.2, and particularly preferably less than 0.1 at a wavelength of 1.5μm between room temperature (20°C) and 1000°C.

[0075] The emissivity mentioned here refers to "normal spectral emissivity." This value is determined based on a measurement principle known as the "blackbody boundary condition" (BBC) and was presented in "DETERMINING THE TRANSMITTANCE AND EMITTANCE OF TRANSPARENT AND SEMITRANSPARENT MATERIALS AT ELEVATED TEMPERATURES"; J. Manara, M. Keller, D. Kraus, M. Arduini-Schuster; 5th European Thermal-Sciences Conference, Netherlands (2008). According to Kirchhoff's radiation law, the normal spectral emissivity of any object is equal to its normal spectral absorptivity (abbreviated here as absorption).

[0076] For room temperature, the absorption A is calculated from the measured hemispherical reflectance R and the measured hemispherical transmission T using the following equation:

[0077] A = 1 – R – T.

[0078] The composite material according to the invention preferably has a content of at least 2.13 g / cm³. 3 More preferably at least 2.14 g / cm³ 3 Or even more preferably at least 2.15 g / cm³ 3 The specific gravity, which is determined according to the Archimedes method.

[0079] Since the composite material according to the invention does not have open-pore porosity, a simple density measurement based on Archimedes' principle is possible. Porosity is determined using density measurement, which takes into account the specific composition of the composite material according to the invention and the specific gravity of the quartz glass matrix and the silicon carbide-containing phase, and thus calculates the porosity (the ratio of pore volume to total volume) as defined above from the specific gravity and proportion of the components used in the composite material according to the invention.

[0080] The composite material according to the invention differs from the composite material described in EP 3 068 739 A in that it additionally incorporates silicon carbide particles. The composite material according to the invention does not have open-cell porosity and is therefore different from the still open-cell silicon composite material described in US2001 / 025001 A. To achieve the desired absorption, it is also not necessary to have as high a proportion of silicon carbide as the material described in US2001 / 025001 A.

[0081] The difference in material properties between the material described in US 2001 / 025001 A and the composite material according to the present invention is due to different production methods. The composite material according to the present invention is produced by slip casting as described below, thereby obtaining a preform with a higher density than the preform produced by dry pressing as described in US 2001 / 025001 A. Therefore, a high-density composite material without open-pore porosity can be achieved by atmospheric sintering even at temperatures below 1400°C, while the dry-pressed Si composite material from US 2001 / 025001 A remains open-pore even when hot-pressed at 1400°C under high pressure (20 MPa to 40 MPa). It is impossible to fully sinter the dry-pressed preform under atmospheric conditions.

[0082] Compared to the SiO2 / Si composite material described in EP 3 068 739 A, the composite material according to the present invention exhibits significantly higher absorption at wavelengths greater than 1 μm in the infrared range at temperatures below 1000 °C. Furthermore, the absorption of the material in this wavelength range is much less dependent on temperature.

[0083] As described below, the composite material according to the invention is sintered under normal atmospheric conditions. Under these sintering conditions, any plastic particles and organic compounds still contained in the powder and the resulting green body (e.g., abrasion from containers and tools, additives such as binders or filter aids), as well as elemental carbon residues due to common impurities in silicon carbide, are burned off and thus removed by reacting with oxygen contained in the air. These reactions occur during heating of the green body at temperatures below 1000°C, where the molded body remains open and the resulting gaseous compounds can easily escape.

[0084] The silicon carbide-containing composite materials described in US 2001 / 025001 A must be sintered under vacuum and pressure to achieve closed-cell porosity. Therefore, these composite materials still contain residual elemental carbon.

[0085] In order to achieve the desired absorption in the composite material according to the invention, it is not necessary to have a high proportion of silicon carbide content (greater than 5% by weight) as in the material in US 2001 / 025001 A.

[0086] The present invention also relates to a method for producing composite materials, and particularly for producing composite materials as described above.

[0087] The method according to the present invention is characterized by the following method steps:

[0088] a. Provide a mixture comprising amorphous quartz glass particles and silicon carbide powder as a suspension;

[0089] b. To obtain a preform by forming a molded body from the suspension generated in step a. of method by slip casting;

[0090] c. Dry the blank; and

[0091] d. Sintering the dried green body obtained from step c.

[0092] The specific details of the individual components described above, such as particle size, particle size distribution, purity, etc., can also be applied to the method according to the present invention, with necessary modifications.

[0093] Method step a. is preferably carried out by mixing silicon carbide powder into an aqueous suspension composed of quartz glass particles. Additionally, in method step a., additives known from ceramic processing technology, such as dispersants, filter aids, and binders, may be added.

[0094] The particle size distribution of the quartz glass particles in the suspension provided in step a. has a d90 value, preferably less than 100 μm, more preferably less than 75 μm, and even more preferably less than 50 μm, as determined by laser diffraction according to ISO 2019:13320 in each case.

[0095] The solid content in the aqueous suspension of quartz glass particles provided in step a. is preferably more than 50% by weight, more preferably more than 65% by weight, and even more preferably more than 75% by weight. The same solid content is also achieved for the resulting mixture of quartz glass particles and silicon carbide powder.

[0096] Silicon carbide powder can be mixed with quartz glass powder before a suspension is formed. For example, dry mixing is suitable for this purpose.

[0097] However, it has been shown that it is particularly advantageous to mix silicon carbide powder into a liquid containing amorphous quartz glass powder, as already mentioned.

[0098] In step a. of the production method according to the invention, silicon carbide powder may preferably be mixed into a liquid containing quartz glass particles in a mixing system having an agitator or a dissolver.

[0099] Before removing the liquid, silicon carbide powder is mixed in. Uniform mixing is particularly easy to achieve in the suspension.

[0100] The solids content, particle size, and particle size distribution of quartz glass particles affect the shrinkage of the preform during subsequent drying. For example, shrinkage during drying can be reduced by using relatively coarse SiO2 particles. In this context, the defined quartz glass powder refers to those quartz glass powders in which amorphous quartz glass particles have a particle size in the range of up to 200 μm, more preferably up to 100 μm, wherein quartz glass particles having a particle size between 1 μm and 60 μm constitute the maximum volume proportion of the quartz glass powder.

[0101] In step b of the production method according to the invention, a slurry molding method is performed such that a mixed suspension of quartz glass particles and silicon carbide powder is filled into a mold containing porous components through which some water is removed from the suspension, thereby forming a dimensionally stable body.

[0102] In step c. of the method, the blank is preferably removed from the mold and dried, wherein any residual water remaining in the blank is evaporated.

[0103] The dried green body obtained from method step c. preferably has a content greater than or equal to 1.60 g / cm³. 3 More preferably greater than or equal to 1.65 g / cm³ 3 Even more preferably greater than or equal to 1.70 g / cm³ 3 The density.

[0104] The slip casting method according to the present invention produces an intermediate state in the form of a preform. Both the slip casting method for the preform and the intermediate product allow for measures to be taken to adjust and modify the properties affecting the final composite material.

[0105] Therefore, processing the starting powders in a suspension facilitates their close mixing and uniform distribution within the green body. The liquid also acts as a binder or activator between the solid components. The liquid can modify the surface of the powder particles and, in particular, cause interactions between them, which can promote a more impermeable and stable bond during subsequent sintering.

[0106] The suspension may be based on an organic solvent, preferably alcohol-based or more preferably water-based. For the interactions mentioned above with quartz glass, the polar nature of the aqueous phase may be advantageous.

[0107] In the preform state, the composite material consisting of a quartz glass phase and a silicon carbide-containing phase is porous and can be modified by gas phase, especially by doping and reactive drying.

[0108] It should be considered that the molded body shrinks significantly during the final sintering in step d. of the process. Typically, the linear shrinkage is about 10%. Therefore, the preform must be larger than the sintered molded body. The sintered molded body is then further machined to obtain the final part. The sintered molded body has a near-net-shape.

[0109] This can be, for example, a solid, hollow, or layered body. The blank can be produced by casting the suspension into a mold. However, other processing methods for the suspension are also suitable, such as layer-by-layer application by dipping, spraying, brushing, applying with a scraper, transferring, laying, scraping, etc.

[0110] The preform is dried, resulting in a largely anhydrous molded body. However, as an inevitable consequence of its production, the preform contains a significant amount of hydroxyl groups. The preform is then typically sintered to form an impermeable, mechanoelastic molded body.

[0111] The method according to the invention may preferably include a method step in which the dried blank obtained from method step c is machined prior to sintering in method step d.

[0112] In step d. of the method, the sintering temperature must be selected to achieve the highest possible density of the composite material. Suitable sintering parameters (sintering temperature, sintering time, and atmosphere) can be determined through simple experiments. Examples of suitable method conditions are described below.

[0113] The sintering process, step d, is carried out at a temperature preferably above or equal to 1300°C, more preferably above or equal to 1325°C, and even more preferably above or equal to 1350°C. The material becomes compressed, and the molded body shrinks, with a linear shrinkage of approximately 10%.

[0114] Method step c. is carried out, particularly at temperatures below 1600°C, more preferably below 1500°C, and even more preferably below 1400°C.

[0115] The duration of step d. depends on the temperature and the initial density of the preform. At 1390°C, 4 hours is usually sufficient for the slip-cast preform to achieve fully closed-cell porosity. At lower temperatures, step e. may take longer.

[0116] The sintering method step d is preferably carried out under atmospheric conditions, i.e., in air and at standard pressure.

[0117] After sintering, the preform made of quartz glass and silicon carbide particles produces a material with a significantly lower hydroxyl content than the material produced by sintering a preform consisting only of SiO2 particles.

[0118] During sintering, the water and hydroxyl groups present are consumed and converted into SiO2. Due to the slip casting production technology, the hydroxyl content in the sintered parts is surprisingly low, preferably below 30 ppm by weight. This results in a relatively high viscosity of the composite material.

[0119] The method of this invention differs from the preparation methods described in WO 2025 / 159866 A and US 2025 / 0236987 A, in which SiC particles are placed in liquid quartz. In contrast, this invention places SiC particles in an aqueous suspension of solid quartz glass particles at room temperature. Following molding using slip casting, sintering occurs in this invention at a temperature below the melting temperature of quartz, thus preventing the formation of liquid quartz throughout the process.

[0120] Because the present invention provides sintering under normal atmospheric conditions, the quartz glass matrix contains pores and is therefore opaque and not as transparent as the materials described in WO 2025 / 159866 A and US 2025 / 0236987 A.

[0121] The present invention also relates to the use of the composite material according to the invention for manufacturing components of processing chambers for wafer production and processing. Components according to the invention are wholly or partially composed of the composite material according to the invention. If a component is only partially composed of the composite material according to the invention, the material preferably forms at least a portion of the surface of the component. Due to the chemical composition of the composite material according to the invention, coatings made from this composite material are particularly suitable for quartz glass, i.e., for the production of quartz glass / composite material composite parts. The component, or at least the surface of the component, possesses the explained optical and structural properties.

[0122] The component according to the invention thus has, at least in some regions, a quartz glass matrix with low porosity and a finely distributed encapsulated silicon carbide phase therein. Even in the case of a thin layer with an extension of about 1 mm, the component according to the invention is opaque in the visible wavelength range, but otherwise largely possesses the typical chemical and mechanical properties of quartz glass.

[0123] In addition to applications requiring high heat absorption and uniform temperature distribution, components are also suitable for applications where high thermal and chemical stability and high resistance to corrosive gases and liquids are important. These requirements are typically present for components used in semiconductor manufacturing, optical devices, and chemical engineering.

[0124] The high emissivity of composite materials makes the components particularly suitable for heat treatment contexts where reproducible and uniform temperature distribution is important.

[0125] Therefore, according to the present invention, the use of the component in a processing chamber in which a semiconductor wafer is processed into a chip is provided. Specifically, the component is used in a system in which high-temperature processes (e.g., CVD, ALD, epitaxy, or annealing) are performed.

[0126] Another intended use of the invention is for components that are heated by radiation (lamp) and for components intended to block thermal radiation.

[0127] The component according to the invention is provided as a component for use in a processing chamber during oxidation or heat treatment, in epitaxy, or in chemical vapor deposition.

[0128] Components can take the form of containers, bowls, shells, solid bodies, or hollow bodies that are extended or curved. In simpler cases, components are designed as plates, rings, flanges, domes, crucibles, or solid or hollow cylinders. Composite materials can be in the form of solids or layers.

[0129] Exemplary Implementation :

[0130] Samples 1 (L12), 2 (L13), 3 (L14), 4 (L15), 5 (L16), 6 (L20), 7 (L21), 8 (L22), 9 (L6), 10 (Reference A), 11 (Reference B), and 12 (Reference C) were produced as follows:

[0131] An aqueous suspension of ground quartz glass particles was used as the starting material for the production of laboratory samples. The suspension had a solids content of 78% by weight and a particle size distribution with a D90 value of 45 μm.

[0132] Using the proportions given in Table 1 (values ​​related to the amount of SiO2), a laboratory stirrer was used to add SiC powder to the suspension.

[0133] The D10, D50, and D90 values ​​of the particle size distribution of SiC powder are as follows:

[0134] SiC powder 1: D10=2.9μm, D50=5.4μm, D90=9.6μm

[0135] SiC powder 2: D10=1.7μm, D50=8.2μm, D90=16.8μm

[0136] Particle size was measured by laser diffraction using a Mastersizer 3000 from Malvern.

[0137] Powder 1 is mainly composed of α-SiC (polymorph 6H), while powder 2 is β-SiC (polymorph 3C). The crystal structure was determined using X-ray diffraction.

[0138] To produce samples, the mixed suspension is poured into a cylindrical mold with a porous bottom. Through this mold, some water is removed from the suspension until a dimensionally stable blank is formed.

[0139] After the formation process is completed, the green body is dried in a drying oven at 60°C until the residual moisture content is <1%.

[0140] The dried green body is then sintered in an electric heating furnace using the sintering parameters given in the table.

[0141] Optical and density measurements were performed on samples cut from the center of the sintered cylindrical mold.

[0142] Color measurements are performed on a cross-sectional area that is bisected along the axis of the sintered molded body.

[0143]

[0144] Figure 1 shows the hemispherical reflection in the visible range and the IR range of a 3 mm thick composite material containing silicon carbide phases with varying amounts of α-silicon carbide, without the silicon carbide phase.

[0145] Figure 2 shows the hemispherical reflection in the visible range and the IR range of a 3 mm thick composite material containing a silicon carbide phase but without a silicon carbide phase and containing silicon carbide phases with different amounts of β-silicon carbide.

[0146] Figure 3 shows the hemispherical transmission in the visible range and the hemispherical reflection in the IR range of a 3 mm thick composite material containing silicon carbide phases with varying amounts of α-silicon carbide but without the silicon carbide phase.

[0147] Figure 4 shows the hemispherical transmission in the visible range and the hemispherical reflection in the IR range of a 3 mm thick composite material containing silicon carbide phases with varying amounts of β-silicon carbide but without the silicon carbide phase.

[0148] Figure 5 shows the calculated hemispherical absorption in the visible range and the calculated hemispherical absorption in the IR range for a 3 mm thick composite material containing silicon carbide phases with varying amounts of α-silicon carbide, without the silicon carbide phase.

[0149] Figure 6 shows the calculated hemispherical absorption in the visible range and the calculated hemispherical absorption in the IR range for a 3 mm thick composite material containing a silicon carbide phase but not containing a silicon carbide phase and containing different amounts of β-silicon carbide.

[0150] Figures 1 and 2 show that, compared with the composite material produced according to EP 3 068 739 A without the silicon carbide phase, the composite material according to the present invention exhibits reduced hemispherical reflection at wavelengths above about 1000 nm.

[0151] Figures 3 and 4 show that the composite material according to the invention exhibits an unusually low transmittance to IR radiation, which is significantly lower than the IR transmittance of the composite material produced according to EP 3 068 739 A without the presence of a silicon carbide phase.

[0152] Figures 5 and 6 show that, compared with the composite material produced according to EP 3 068 739 A without the silicon carbide phase, the composite material according to the present invention exhibits high absorption at wavelengths above approximately 1000 nm.

[0153] Figure 7 shows the emissivity of the composite material according to the invention with 2.5 wt% α-silicon carbide at different temperatures of 500°C, 750°C and 1000°C at elevated temperatures.

[0154] As is clear from Figure 7, the emissivity of the composite material according to the invention increases with increasing temperature in the wavelength range of 1 μm to 5 μm, reaching up to 0.8 at 1000 °C. However, the temperature dependence of the emissivity fluctuates very little.

[0155] The absorptivity of the composite material according to the invention at high temperatures was determined by measuring emissivity. The temperature behavior of the absorptivity of a sample with 2.5 wt% silicon carbide in the near-infrared at a wavelength of 1.5 μm is shown in Figure 10 and Table 2 below.

[0156] Figure 8 shows a SEM image of a cross-sectional region of the composite material according to the invention, containing 2.5 wt% silicon carbide, sintered at 1390 °C for 5 hours. P represents pores, and SiC represents SiC particles embedded in a quartz glass matrix.

[0157] Figure 9 shows a SEM image of a cross-sectional region of the composite material according to the invention, containing 2.5 wt% silicon carbide, sintered at 1390 °C for 10 hours. P represents pores, and SiC represents SiC particles embedded in a quartz glass matrix.

[0158] Figures 8 and 9 show the composite material according to the invention, which has low porosity. Longer sintering increases the porosity.

[0159] Table 2

[0160]

Claims

1. A composite material comprising a matrix made of quartz glass, wherein regions containing a silicon carbide phase are embedded in the matrix.

2. The composite material according to claim 1, characterized in that, The 3mm thick disk of the composite material has an absorption of more than 40%, more preferably more than 50%, at 1500nm.

3. The composite material according to claim 1 or 2, characterized in that, The 3mm thick disk of the composite material has a hemispherical reflection of less than 60%, more preferably less than 50%, at 1500nm.

4. The composite material according to any one of claims 1 to 3, characterized in that, The composite material has a transmittance of less than 10%, more preferably less than 1%, and even more preferably less than 0.6% in the wavelength range of 0.4 to 2.5 μm for a 3 mm thick disk.

5. The composite material according to any one of claims 1 to 4, characterized in that, The composite material has an absorption capacity / emissivity of less than 0.3, more preferably less than 0.2, and particularly preferably less than 0.1 at a wavelength of 1.5 μm for a 3 mm disk between room temperature (20 °C) and 1000 °C.

6. The composite material according to any one of claims 1 to 5, characterized in that, The weight percentage of the silicon carbide phase, in each case based on the matrix made of quartz glass, is 0.25% to 10% by weight, more preferably 0.5% to 9% by weight, even more preferably 1% to 8% by weight, even more preferably 1.5% to 7% by weight, even more preferably 2% to 6% by weight, even more preferably 2.5% to 5% by weight.

7. The composite material according to any one of claims 1 to 6, characterized in that, d of the particle size distribution of silicon carbide particles 50 The value is 0.1 μm to 100 μm, more preferably 0.5 μm to 75 μm, even more preferably 1 μm to 50 μm, even more preferably 2 μm to 25 μm.

8. The composite material according to any one of claims 1 to 7, characterized in that, The composite material contains less than 100 ppm, more preferably less than 50 ppm, and even more preferably less than 25 ppm of metallic impurities, which are determined by inductively coupled plasma optical emission spectroscopy.

9. The composite material according to any one of claims 1 to 8, characterized in that, The composite material has a porosity of less than 8%, more preferably less than 6%, and even more preferably less than 5%, wherein the porosity is defined as the pore volume based on the total volume of the composite material.

10. The composite material according to any one of claims 1 to 9, characterized in that, The composite material has a carbon content of less than 0.1% by weight, more preferably less than 0.075% by weight, and even more preferably less than 0.05% by weight, based on the total weight of the composite material in each case.

11. The composite material according to any one of claims 1 to 10, characterized in that, The composite material is carbon-free.

12. A method for producing a composite material according to any one of claims 1 to 11, characterized in that... The following method steps: a. providing a mixture comprising amorphous quartz glass particles and silicon carbide powder as a suspension; b. forming a molded body from the suspension generated in method step a. by a slip casting method to obtain a preform; c. Dry the green body; and d. Sinter the dried green body obtained from step c.

13. The method according to claim 12, characterized in that, The quartz glass particles in the suspension have a particle size distribution having a d90 value of less than 100 μm, more preferably less than 75 μm, and even more preferably less than 50 μm, as determined by laser diffraction according to ISO 2019:13320 in each case.

14. The method according to claim 12 or 13, characterized in that, The solid content in the aqueous suspension composed of quartz glass particles is more than 50% by weight, more preferably more than 65% by weight, and even more preferably more than 75% by weight.

15. Use of a composite material according to any one of claims 1 to 11 for producing components for a processing chamber in which semiconductor crystals are processed into chips, systems for which high-temperature processes are performed, components for heating by radiation, and parts for blocking thermal radiation.

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