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EP-4737414-A1 - OPAQUE QUARTZ GLASS HAVING HIGH ABSORPTION IN THE INFRARED RANGE

EP4737414A1EP 4737414 A1EP4737414 A1EP 4737414A1EP-4737414-A1

Abstract

The invention relates to an opaque quartz glass having high absorption in the near infrared range and to a method for producing same. The present invention also relates to the use of the opaque quartz glass according to the invention or the opaque quartz glass resulting from the method according to the invention in process chambers in which semiconductor wafers are processed.

Inventors

  • Dr. Götzendorfer, Andreas
  • TSCHOLITSCH, Nadine
  • HAMMERSCHMIDT, Jörg
  • JENEK, TORSTEN
  • Dr. Wessely, Frank

Assignees

  • Heraeus Quarzglas GmbH & Co. KG

Dates

Publication Date
20260506
Application Date
20251022

Claims (15)

  1. A composite material comprising a matrix which is made of quartz glass and into which regions of a silicon carbide-containing phase are embedded.
  2. The composite material according to claim 1, characterized in that the composite material has an absorption of a 3 mm thick disk at 1500 nm of greater than 40%, more preferably greater than 50%.
  3. The composite material according to claim 1 or 2, characterized in that the composite material has a hemispherical reflection of a 3 mm thick disk at 1500 nm of less than 60%, more preferably less than 50%.
  4. The composite material according to any of claims 1 to 3, characterized in that the composite material has a transmission of a 3 mm thick disk of less than 10%, more preferably less than 1%, even more preferably less than 0.6%, in the wavelength range from 0.4 to 2.5 µm.
  5. The composite material according to any of claims 1 to 4, characterized in that the composite material has a change in the absorption capacity / emissivity of a 3 mm disk at a wavelength of 1.5 µm between room temperature (20°C) and 1000°C of less than 0.3, more preferably less than 0.2, particularly preferably less than 0.1.
  6. The composite material according to any of claims 1 to 5, characterized in that the weight proportion of the silicon carbide-containing phase, in each case based on the matrix made of quartz glass, is 0.25 to 10 wt.%, more preferably 0.5 to 9 wt.%, even more preferably 1 to 8 wt.%, even more preferably 1.5 to 7 wt.%, even more preferably 2 to 6 wt.%, even more preferably 2.5 to 5 wt.%.
  7. The composite material according to any of claims 1 to 6, characterized in that the d 50 value of the particle size distribution of the silicon carbide particles is 0.1 to 100 µm, more preferably 0.5 to 75 µm, even more preferably 1 to 50 µm, even more preferably 2 to 25 µm.
  8. The composite material according to any of claims 1 to 7, characterized in that the composite material has metal impurities of less than 100 ppm, more preferably less than 50 ppm, even more preferably less than 25 ppm, the metal impurities being determined by optical emission spectroscopy with inductively coupled plasma.
  9. The composite material according to any of claims 1 to 8, characterized in that the composite material has a porosity of less than 8%, more preferably less than 6%, even more preferably less than 5%, the porosity being defined as the pore volume based on the total volume of the composite material.
  10. The composite material according to any of claims 1 to 9, characterized in that the composite material has a carbon content of less than 0.1 wt.%, more preferably less than 0.075 wt.%, even more preferably less than 0.05 wt.%, in each case based on the total weight of the composite material.
  11. The composite material according to any of claims 1 to 10, characterized in that the composite material is free of carbon.
  12. A method for producing the composite material according to any of claims 1 to 11, characterized by the following method steps: a. providing a mixture comprising amorphous quartz glass particles and a silicon carbide-containing powder as a suspension; b. forming a shaped body by means of a slip casting method starting from the suspension produced in method step a. to obtain a green body; c. drying the green body; and d. sintering the dried green body resulting from method step c.
  13. The method according to claim 12, characterized in that the grain size distribution of the quartz glass particles in the suspension has a d90 value of less than 100 µm, more preferably less than 75 µm, even more preferably less than 50 µm, in each case determined by laser diffraction according to ISO 2019:13320.
  14. The method according to claim 12 or 13, characterized in that the solids content in the aqueous suspension consisting of quartz glass particles is more than 50 wt.%, more preferably more than 65 wt.%, even more preferably more than 75 wt.%.
  15. A use of a composite material according to any of claims 1 to 11 for producing a part for components of process chambers in which semiconductor wafers are processed into chips, for systems in which high-temperature processes are carried out, for components which are heated by means of radiation and for components which block thermal radiation.

Description

The invention relates to an opaque quartz glass having high absorption in the infrared wavelength range from 1 to 10 µm, and to a method for producing same. The present invention also relates to the use of the opaque quartz glass according to the invention or the opaque quartz glass resulting from the method according to the invention in process chambers in which semiconductor wafers are processed. A variety of devices are used in the production of semiconductor components and optical displays, such as reactors, apparatus, support plates, bell jars, crucibles, protective shields or simpler components such as tubes, rods, plates, flanges, rings or blocks. They must meet high requirements in terms of purity, chemical and thermal stability and mechanical strength. They can be made of stainless steel, for example, but are increasingly being made of quartz glass. The reason for this is that the silicon dioxide material, at high purity, is inert to conventional semiconductor materials. Quartz glass is also characterized by high chemical stability with respect to numerous process media and also by high thermal shock resistance. Some components in process chambers where semiconductor wafers are processed at high temperatures are heated by means of radiation from lamps. In order to ensure fast and efficient heat transfer, the material used for this purpose must have high absorption, in particular in the near infrared, i.e., in the range from 1 to 3 µm. Since the components must also have low thermal mass in order to enable rapid thermal cycles of heating and cooling, high absorption must be achieved even when the components are very thin or have a small wall thickness. Since process control is difficult when the absorption of the material is heavily dependent on the temperature, it is advantageous for the absorption to be dependent on the temperature to the smallest possible extent. These (infrared) optical properties should be combined, as far as possible, with the proven properties of high-purity quartz glass for applications in process chambers for wafer processing. 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 for quartz glass. Corresponding quartz glass materials are described, for example, in EP 3 068 739 A. The material described is a composite material comprising a matrix which is made of quartz glass in which regions of a silicon-containing phase are embedded. Although the composite material has a high absorption at visible wavelengths and in the near infrared up to 1 µm, the absorption drops significantly at room temperature. It is only at higher temperatures that the absorption increases for a wavelength range of greater than 1 µm, and reaches a constant value from approximately 1000°C. However, at lower temperatures, infrared absorption is highly temperature dependent, which makes process control difficult and therefore disadvantageous. Another composite material proposed for applications in process chambers for wafer processing is known from US 2001/025001 A. The composite material consists of quartz glass and a second phase made of silicon, silicon carbide, silicon nitride, titanium nitride or titanium carbide. The aim is to provide a material that is less vulnerable to cracking during mechanical processing than quartz glass and that releases fewer particles. Due to the production method, the composite material has an open porosity of less than 15% or less than 5%. Open-pored materials are very difficult to clean, in particular with liquids or acids. During mechanical processing, impurities can penetrate into open pore channels. It is virtually impossible to remove these impurities without leaving residues. Furthermore, optical properties of the resulting material are not described and - as long as silicon carbide is the second phase in the composite - the resulting material from US 2001/025001 A contains carbon. This results from the production method used: silicon carbide as a starting material always contains carbon as an impurity, and this is not removed in the described production method of vacuum sintering under pressure. JP 2006/027930 A relates to a black quartz glass, the black color being caused by the incorporation of graphite particles. The quartz glass is produced by sintering from a mixture of amorphous quartz glass powder (soot) and graphite powder having defined grain size distributions. The carbon particles used make up 0.05 to 2 wt.% of the SiO2 weight, the diameters are 0.07 to 0.5 µm or 0.05 to 1 µm. Inter alia, ground quartz glass is used as the SiO2 powder, which quartz glass is produced by flame hydrolysis in a hydrogen/oxygen flame. The resulting material is sintered at 1100 to 1500°C. At temperatures that are too high, a decrease in the density of the quartz glass is observed, due to the form