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US-12623953-B2 - Glass composition, glass article and use thereof

US12623953B2US 12623953 B2US12623953 B2US 12623953B2US-12623953-B2

Abstract

A glass composition includes oxides which form non-volatile fluorides at a temperature of 150° C. and a pressure of 5 Pa or less and are present in an amount of less than 0.5 mol % in the glass composition, based on all oxides present in the glass composition. A working point of the glass composition is 1400° C. or less. The glass composition has a hydrolytic resistance characterized by a leachability of GeO 2 , P 2 O 5 and/or B 2 O 3 from the glass composition determined as concentrations in an eluate prepared according to ISO 719 of at least one of the following: less than 70 mg/l GeO 2 in the eluate per 1 mol % GeO 2 in the glass composition; less than 70 mg/l P 2 O 5 in the eluate per 1 mol % P 2 O 5 in the glass composition; or less than 300 mg/l B 2 O 3 in the eluate per 1 mol % B 2 O 3 in the glass composition.

Inventors

  • Ulrich Fotheringham
  • Martin Letz
  • Azatuhi Ayrikyan
  • Thomas Pfeiffer
  • Simone Monika Ritter
  • Silke Wolff
  • Tobias Gotschke
  • Christoph Gross
  • Antje Greiff
  • Jens Ulrich Thomas

Assignees

  • SCHOTT AG

Dates

Publication Date
20260512
Application Date
20231222
Priority Date
20210622

Claims (20)

  1. 1 . A glass composition, comprising oxides which form non-volatile fluorides at a temperature of 150° C. and a pressure of 5 Pa or less and are present in an amount of less than 0.5 mol % in the glass composition, based on all oxides present in the glass composition, wherein a working point of the glass composition is 1400° C. or less, wherein the glass composition has a hydrolytic resistance characterized by a leachability of GeO 2 , P 2 O 5 and/or B 2 O 3 from the glass composition determined as concentrations in an eluate prepared according to ISO 719 of at least one of the following: less than 70 mg/l GeO 2 in the eluate per 1 mol % GeO 2 in the glass composition; less than 70 mg/l P 2 O 5 in the eluate per 1 mol % P 2 O 5 in the glass composition; or less than 300 mg/l B 2 O 3 in the eluate per 1 mol % B 2 O 3 in the glass composition; wherein the glass composition comprises, based on all oxides present in the glass composition, at least 2 mol % TiO 2 and/or at least 2 mol % Nb 2 O 5 .
  2. 2 . The glass composition of claim 1 , wherein the glass composition comprises at least 4 mol % TiO 2 and/or at least 4 mol % Nb 2 O 5 .
  3. 3 . The glass composition of claim 1 , wherein the glass composition comprises, based on all oxides present in the glass composition, 5 to 30 mol % GeO 2 .
  4. 4 . The glass composition of claim 3 , wherein the glass composition comprises 10 to 18 mol % GeO 2 .
  5. 5 . The glass composition of claim 1 , wherein the glass composition is free, except for impurities, of alkali metal oxides and alkali earth metal oxides.
  6. 6 . The glass composition of claim 1 , wherein the glass composition comprises, based on all oxides present in the glass composition: 10 to 55 mol % SiO 2 ; 5 to 30 mol % B 2 O 3 ; 5 to 30 mol % P 2 O 5 ; wherein a sum of B 2 O 3 , P 2 O 5 , GeO 2 , TiO 2 and Nb 2 O 5 is at least 35 mol and a sum of B 2 O 3 and P 2 O 5 is less than 35 mol %.
  7. 7 . The glass composition of claim 1 , wherein the glass composition exclusively comprises oxides which form volatile fluorides at a temperature of 150° C. and a pressure of 5 Pa or less.
  8. 8 . The glass composition of claim 1 , wherein the glass composition has an average coefficient of thermal expansion, measured according to DIN ISO 7991:1987 in a temperature range of 20° C. to 300° C. that is from 1 to 6 ppm/K.
  9. 9 . The glass composition of claim 1 , wherein the glass composition has a refractive index of between 1.45 and 1.80 and/or an Abbe number that is at least 45.
  10. 10 . The glass composition of claim 1 , comprising, based on all oxides present in the glass composition: 10 to 55 mol % SiO 2 ; 5 to 30 mol % B 2 O 3 ; 5 to 30 mol % P 2 O 5 ; 5 to 30 mol % GeO 2 ; and at least 2 mol % TiO 2 and/or at least 2 mol % Nb 2 O 5 ; wherein a sum of B 2 O 3 , P 2 O 5 , GeO 2 , TiO 2 and Nb 2 O 5 is at least 35 mol and a sum of B 2 O 3 and P 2 O 5 is less than 35 mol %.
  11. 11 . The glass composition of claim 1 , wherein a molar ratio between B 2 O 3 and P 2 O 5 is from 1:2 to 2:1.
  12. 12 . The glass composition of claim 1 , wherein a total amount of Ti 2 O 3 and TiO in the glass composition is less than 0.5 mol and/or a total amount of NbO 2 and NbO in the glass composition is less than 0.5 mol %, based on all oxides present in the glass composition.
  13. 13 . A glass article, comprising, a glass composition comprising oxides which form non-volatile fluorides at a temperature of 150° C. and a pressure of 5 Pa or less and are present in an amount of less than 0.5 mol % in the glass composition, based on all oxides present in the glass composition, wherein a working point of the glass composition is 1400° C. or less, wherein the glass composition has a hydrolytic resistance characterized by a leachability of GeO 2 , P 2 O 5 and/or B 2 O 3 from the glass composition determined as concentrations in an eluate prepared according to ISO 719 of at least one of the following: less than 70 mg/l GeO 2 in the eluate per 1 mol % GeO 2 in the glass composition; less than 70 mg/l P 2 O 5 in the eluate per 1 mol % P 2 O 5 in the glass composition; or less than 300 mg/l B 2 O 3 in the eluate per 1 mol % B 2 O 3 in the glass composition; wherein the glass article is at least one of the following: formed as a sheet, a plate, a bar, and/or a flat glass; a surface-structured and/or etched wafer, a surface-structured and/or etched optical wafer, and/or a glass waveguide panel; a substrate glass for a radio-frequency microelectromechanical system; or an article structured via reactive ion etching.
  14. 14 . The glass article of claim 13 , wherein the glass article has one or more of the following properties: a difference of an average coefficient of thermal expansion of the glass article and polycrystalline silicon is less than 1.0 ppm/K measured according to DIN ISO 7991:1987 in a temperature range of 20° C. to 300° C.; a surface roughness, measured according to ISO 25178:2010-2020, of 100 nm or less; trenches on a surface, wherein an aspect ratio of a trench depth to a width is at least 5:1; an etch rate of 0.03 μm min −1 or more, determined in an etch rate test using CHF 3 /O 2 -plasma (97.5 vol. %/2.5 vol. %) at 700 eV, at 200 μA cm −2 , at an ion incidence angle of 0°, using an ion beam etch apparatus ISA150 with a 6″-Kaufman ion beam source with neutralisation; or the glass article is a wafer with a thickness >0.2 mm and a warp of 200 μm or less according to ASTM F657: 1999.
  15. 15 . The glass article of claim 13 , wherein the glass composition comprises, based on all oxides present in the glass composition: 10 to 55 mol % SiO 2 ; 5 to 30 mol % B 2 O 3 ; 5 to 30 mol % P 2 O 5 ; wherein a sum of B 2 O 3 , P 2 O 5 , GeO 2 , TiO 2 and Nb 2 O 5 is at least 35 mol and a sum of B 2 O 3 and P 2 O 5 is less than 35 mol %.
  16. 16 . The glass article of claim 13 , wherein the glass article comprises, based on all oxides present in the glass composition: 10 to 55 mol % SiO 2 ; 5 to 30 mol % B 2 O 3 ; 5 to 30 mol % P 2 O 5 ; 5 to 30 mol % GeO 2 ; and at least 2 mol % TiO 2 and/or at least 2 mol % Nb 2 O 5 ; wherein a sum of B 2 O 3 , P 2 O 5 , GeO 2 , TiO 2 and Nb 2 O 5 is at least 35 mol and a sum of B 2 O 3 and P 2 O 5 is less than 35 mol %.
  17. 17 . The glass article of claim 13 , wherein the glass composition has a molar ratio between B 2 O 3 and P 2 O 5 that is from 1:2 to 2:1.
  18. 18 . The glass article of claim 13 , wherein a total amount of Ti 2 O 3 and TiO in the glass composition is less than 0.5 mol and/or a total amount of NbO 2 and NbO in the glass composition is less than 0.5 mol %, based on all oxides present in the glass composition.
  19. 19 . The glass article of claim 13 , wherein the glass composition has a refractive index of between 1.45 and 1.80 and/or an Abbe number that is at least 45.
  20. 20 . A glass composition, comprising oxides which form non-volatile fluorides at a temperature of 150° C. and a pressure of 5 Pa or less and are present in an amount of less than 0.5 mol % in the glass composition, based on all oxides present in the glass composition, wherein a working point of the glass composition is 1400° C. or less, wherein the glass composition has a hydrolytic resistance characterized by a leachability of GeO 2 , P 2 O 5 and/or B 2 O 3 from the glass composition determined as concentrations in an eluate prepared according to ISO 719 of at least one of the following: less than 70 mg/l GeO 2 in the eluate per 1 mol % GeO 2 in the glass composition; less than 70 mg/l P 2 O 5 in the eluate per 1 mol % P 2 O 5 in the glass composition; or less than 300 mg/l B 2 O 3 in the eluate per 1 mol % B 2 O 3 in the glass composition; wherein the glass composition comprises, based on all oxides present in the glass composition: 10 to 55 mol % SiO 2 ; 5 to 30 mol % B 2 O 3 ; and 5 to 30 mol % P 2 O 5 ; wherein a sum of B 2 O 3 , P 2 O 5 , GeO 2 , TiO 2 and Nb 2 O 5 is at least 35 mol and a sum of B 2 O 3 and P 2 O 5 is less than 35 mol %.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This is a continuation of International Patent Application No. PCT/EP2022/066881 entitled “GLASS COMPOSITION, GLASS ARTICLE AND USE THEREOF,” filed on Jun. 21, 2022, which is incorporated in its entirety herein by reference. International Patent Application No. PCT/EP2022/066881 claims priority to European Patent Application No. 21180891.0 filed on Jun. 22, 2021, which is incorporated in its entirety herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to glass compositions, glass articles and their use. The glass compositions are particularly useful and suitable in the context of reactive ion etching applications. 2. Description of the Related Art In view of the trend towards increased miniaturisation across a broad spectrum of industries, the development of micro-optical and microstructured elements, such as lenses, mirrors and (optical) waveguides, is a very active field of research. Reactive ion etching (RIE) is a known technology suitable for the microstructuring of precursor elements that allows, for example, the manufacture of microstructured SiO2 wafers via a masking technique in a plasma generator. During the microstructuring process of a pure SiO2 (precursor) product with CF4 or another suitable fluorine-containing gas, volatile tetrafluorosilane is formed, but due to its gaseous state of matter tetrafluorosilane is not deposited on the (precursor) product. Quartz glass, also referred to as vitreous silica, is known for its excellent chemical resistance. Although pure SiO2 glass has many further advantages in the context of RIE microstructuring and can be obtained in a variety of shapes, there are a number of drawbacks. The high melting temperature of SiO2 and the concomitantly high manufacturing temperature, also referred to as working point, comes at high production costs and simultaneous burden for the environment (“carbon dioxide footprint”). Certain desired product geometries can only be obtained in laborious and costly post-processing steps. A further disadvantage during wafer level assembly processes, wherein glass wafers and semiconductor materials are joined, is the small average coefficient of thermal expansion of SiO2 of around 0.5 ppm/K. Glass compositions with an average coefficient of thermal expansion matching known semiconductor materials, e.g. in a range of 2 to 8 ppm/K, and which can be manufactured into a variety of desired shapes at comparably low cost are hence more desirable. All commercially available glass compositions which fulfil these desired properties, regarding their geometries, average coefficients of thermal expansion and refractive indices, have the drawback of formation of solid fluorides during RIE, which are consequently deposited on the glass surface immediately after their formation. With the exception of SiO2, most bulk glasses suffer from this drawback because the majority of chemical elements typically found in glass compositions form solid fluorides (at room temperature). DE 10 2005 034 785 B3 describes glasses whose (oxide) components exclusively form volatile fluorides when reacted with fluorine at room temperature (25° C.). The described glasses can be melted in conventional melting units, such as tanks or crucibles, as their melting temperature is in a range of 1500° C. to 1750° C. and thus well below the melting temperature of SiO2. The described glasses can be produced in various required geometries and have expansion coefficients compatible with silicon. The described glasses are however limited in their chemical resistance and robustness, in particular when subject to manufacturing conditions which are typical for semiconductor processing. US 2008/0179294 A1 describes glasses whose oxides form non-volatile fluorides at a temperature of 150° C. and a pressure of 5 Pa or less. The glasses described in US 2008/0179294 A1 belong to a group of glasses in which the sum of glass-forming elements Si, B, P and Ge is less than 50 mol %, based on their oxides. Such glass compositions generally have a high tendency to crystallise and are known for their steep viscosity behaviour which makes their production challenging (Calahoo & Wondraczek, Ionic glasses: Structure, properties and classification, J. Non-Crystalline Solids: X 8, 2020, 100054). The glasses described in US 2008/0179294 A1 rely on a high content of B2O3 in order to improve the meltability. However, a high content of B2O3 is detrimental for the chemical resistance of the resulting glasses. Furthermore, B2O3-rich glasses are hygroscopic. What is needed in the art is a way to overcome the limitations of the glass compositions described in the art. SUMMARY OF THE INVENTION In some embodiments provided according to the invention, a glass composition includes oxides which form non-volatile fluorides at a temperature of 150° C. and a pressure of 5 Pa or less and are present in an amount of less than 0.5 mol % in