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KR-20260066750-A - Growth of strontium tetraborate crystals

KR20260066750AKR 20260066750 AKR20260066750 AKR 20260066750AKR-20260066750-A

Abstract

A method for growing strontium tetraborate ( SrB₄O₇ ) crystals is provided. The method comprises the step of lowering a seed crystal into a melt having a mixture containing sources of Sr, B, O, and Cl. The method also comprises the step of heating and melting the mixture to a temperature sufficient to form strontium tetraborate crystals.

Inventors

  • 추앙 융-호 알렉스
  • 필덴 존
  • 마우저 켈리
  • 가르시아 베리오스 에드가르도

Assignees

  • 케이엘에이 코포레이션

Dates

Publication Date
20260512
Application Date
20240829
Priority Date
20240624

Claims (20)

  1. As a method for growing strontium tetraborate ( SrB₄O₇ ) crystals, It includes a step of lowering a seed crystal into the melt, and The above melt is, Forming a mixture containing sources of Sr. B, O, and Cl; and Heating and melting the mixture to a sufficient temperature to form strontium tetraborate crystals A method for growing strontium tetraborate ( SrB₄O₇ ) crystals, comprising
  2. In paragraph 1, A method for growing strontium tetraborate (SrB₄O₇) crystals, wherein the mixture of Sr, B, O, and Cl is heated and melted to a temperature of approximately 960-1030°C, and then cooled to a temperature of approximately 950 ° C to form the strontium tetraborate crystals.
  3. In paragraph 1, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals, wherein the source of Cl is SrCl₂ .
  4. In paragraph 1, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals, wherein the source of Sr, B, O, and Cl comprises at least one of B₂O₃ , SrCO₃ , and SrCl₂ .
  5. In paragraph 3, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals, wherein the melt contains approximately 0.5-34 mol% of SrCl₂ .
  6. In paragraph 4, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals, wherein the melt contains approximately 0.5-34 mol% of SrCO₃ .
  7. In paragraph 4, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals , wherein the melt contains approximately 66-90 mol% B₂O₃ .
  8. In paragraph 3, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals, wherein the melt contains approximately 2-15 mol% SrCl₂ .
  9. In paragraph 1, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals, wherein the above melt additionally contains a source of H₂O .
  10. In paragraph 1, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals, further comprising the step of growing the strontium tetraborate crystals by a top-seeded solution method.
  11. In paragraph 1, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals, further comprising the step of growing strontium tetraborate crystals by a flux method.
  12. In paragraph 1, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals, further comprising the step of growing strontium tetraborate crystals by a melt method.
  13. In paragraph 1, A method for growing strontium tetraborate ( SrB₄O₇ ) crystals comprising a seed crystal of an alternating crystal plate to enable quasi-phase matching.
  14. In paragraph 1, A method for growing strontium tetraborate (SrB₄O₇) crystals, wherein the mixture of Sr, B, O, and Cl is heated and melted to a temperature of approximately 960-1030°C, and then cooled to a temperature of approximately 900 ° C to form the strontium tetraborate crystals.
  15. In paragraph 1, A method for growing strontium tetraborate (SrB₄O₇) crystals, wherein the mixture of Sr, B, O, and Cl is heated and melted to a temperature of approximately 960-1030°C, and then cooled to a temperature of approximately 875 ° C to form the strontium tetraborate crystals.
  16. In paragraph 1, A method for growing strontium tetraborate (SrB₄O₇) crystals, wherein the mixture of Sr, B, O, and Cl is heated and melted to a temperature of approximately 1001-1030°C, and then cooled to a temperature of approximately 1000 ° C to form the strontium tetraborate crystals.
  17. In paragraph 1, A method for growing strontium tetraborate (SrB₄O₇) crystals, wherein the mixture of Sr, B, O, and Cl is heated and melted to a temperature of approximately 1016-1030°C, and then cooled to a temperature of approximately 1015 ° C to form the strontium tetraborate crystals.
  18. In paragraph 1, A method for growing strontium tetraborate (SrB₄O₇) crystals, wherein the mixture of Sr, B, O, and Cl is heated and melted to a temperature of approximately 960-1030°C, and then cooled to a temperature of approximately 875-1015 ° C to form the strontium tetraborate crystals.
  19. A frequency converter comprising a crystal grown by the method of claim 1.
  20. A linear optical device comprising a crystal grown by the method of claim 1.

Description

Growth of strontium tetraborate crystals <Cross-reference to related applications> This application relates to U.S. provisional application No. 63/656,193 (filed June 5, 2024) and U.S. provisional application No. 63/537,558 (filed September 11, 2023), the contents of which are incorporated herein by reference in their entirety. The present disclosure relates to crystal growth, and more specifically, to the growth of strontium tetraborate (SrB₄O₇), a single-crystal material for linear or non-linear optical components such as mirrors, lenses, prisms, beam splitters, windows, lamp cells, quasi-phase matching, and other frequency conversion designs for use in metrology and inspection systems in the semiconductor manufacturing field, including photomasks, reticles, and semiconductor wafers, and for inspection and / or measurement. As the dimensions of semiconductor devices shrink, the size of the smallest particle or pattern defect that can cause the device to fail also shrinks. Consequently, there is a need to detect smaller particles and defects on patterned semiconductor wafers and reticles. The intensity of light scattered by particles smaller than the wavelength of the light is generally scaled in proportion to higher powers of the particle's dimensions (for example, the total intensity of light scattered from an isolated small spherical particle is proportional to the sixth power of the sphere's diameter and inversely proportional to the fourth power of the wavelength). Due to the increased intensity of the scattered light, shorter wavelengths generally provide better sensitivity for detecting smaller particles and defects than longer wavelengths. Therefore, high-speed inspection in the semiconductor industry is typically performed on machines utilizing ultraviolet light. One method for generating ultraviolet (UV) light involves frequency conversion from longer wavelengths to UV wavelengths using a non-linear crystal that is transparent to UV. Because the intensity of light scattered from small particles and defects is generally very low, high illumination intensity is required to generate a signal that can be detected in a very short time. In addition to the requirement of high UV transmittance, this necessitates the use of windows, lenses, and other optical devices with high damage thresholds. Linear and nonlinear optical crystals are used, for example, in microscopes, telescopes, virtual reality systems, lasers, and semiconductor systems. Optical crystals are widely used in semiconductor inspection and measurement systems, including prisms, lenses, laser crystals, and windows, among other components. Optical crystals that are transparent in deep ultraviolet (DUV) and vacuum ultraviolet (VUV) light at approximately 200–280 nm and 100–200 nm, respectively, are rare. The most commonly used optical crystals for linear optical applications are calcium fluoride and magnesium fluoride, which transmit light with wavelengths as short as approximately 130 nm. However, most fluorides are hygroscopic or absorb water from the atmosphere. This water will absorb UV light, and the absorbed water can cause stress on the crystal, which can alter the shape of the optical instrument and reduce its performance. Nonlinear optical crystals capable of frequency conversion for wavelengths shorter than approximately 190 nm are not commercially available. Several materials, such as potassium beryllium fluoroborate ( KBe₂BO₃F₂ ; KBBF) and other materials in the ABe₂BO₃F₂ (A=Na, K, Rb, Cs, Tl , NH₄ ) family , can transmit wavelengths shorter than 190 nm and are phase- matched . However, the transmittance of KBBF drops significantly for wavelengths shorter than 190 nm. Additionally, mass production of these materials has not yet been achieved, and further research is required regarding their damage thresholds and lifetimes. Strontium tetraborate, SrB₄O₇ (SBO) is a material that overcomes many of the aforementioned obstacles. SBO exhibits transmittance down to short wavelengths of approximately 125 nm (YS Oseledchik, AL Prosvirnin, AI Pisarevskiy, VV Starshenko, VV Osadchuk, SP Belokrys, NV Svitanko, AS Korol, SA Krikunov and AF Selevich, “New nonlinear optical crystals: strontium and lead tetraborate,” Opt. Mater 4, 669 (1995), the entire contents of which are incorporated herein by reference), is non-hygroscopic, and has a damage threshold of 16.4 J/cm2 at 266 nm, which is higher than other nonlinear crystals such as CaF2 (Tanaka et al., “High surface laser-induced damage threshold of SBO single crystal under 266 nm (DUV) laser irradiation” Optics Express, 28, 20 29239 (2020)) and CLBO. SBO cannot be phase-matched in DUV or VUV due to the small birefringence of DUV or VUV, but it has a large d33 nonlinearity coefficient and can therefore be quasi-phase-matched. U.S. Provisional Application No. 63/038,134, filed June 12, 2020, with the title "177nm and 133nm CW Lasers Using Stacked Strontium Tetraborate Plates"; U.S. Provisional App