Loading patent…
AssigneeHeraeus Quarzglas GmbH & Co. KG
InventorsKlaus Becker, Stefan Ochs, Stephan Thomas
Estimating the term…
A blank made of titanium-doped silica glass for a mirror substrate for use in EUV lithography is provided. The blank includes a surface portion to be provided with a reflective film and having an optically used area (CA) over which a coefficient of thermal expansion (CTE) has a two-dimensional inhomogeneity (dCTE) distribution profile averaged over a thickness of the blank. A maximum inhomogeneity (dCTEmax) of less than 5 ppb/K is defined as a difference between a CTE maximum value and a CTE minimum value. The dCTEmax is at least 0.5 ppb/K. The CA forms a non-circular area having a centroid. The dCTE distribution profile is not rotation-symmetrical and is defined over the CA, such that straight profile sections normalized to a unit length and extending through the centroid of the area yield a dCTE family of curves forming a curve band with a bandwidth of less than 0.5×dCTEmax.
A blank made of titanium-doped silica glass for a mirror substrate for use in EUV lithography, the blank comprising a surface portion configured to be provided with a reflective film and having an optically used area (CA) over which a coefficient of thermal expansion (CTE) has a two-dimensional inhomogeneity (dCTE) distribution profile averaged over a thickness of the blank, a maximum inhomogeneity (dCTEmax) of less than 5 ppb/K being defined as a difference between a CTE maximum value and a CTE minimum value,
A blank made of titanium-doped silica glass for a mirror substrate for use in EUV lithography, the blank comprising a surface portion configured to be provided with a reflective film and having an optically used area (CA) over which a coefficient of thermal expansion (CTE) has a two-dimensional inhomogeneity (dCTE) distribution profile averaged over a thickness of the blank, a maximum inhomogeneity dCTEmax) of less than 5 ppb/K being defined as a difference between a CTE maximum value and a CTE minimum value,
A blank made of titanium-doped silica glass for a mirror substrate for use in EUV lithography, the blank comprising a surface portion configured to be provided with a reflective film and having an optically used area (CA) over which a coefficient of thermal expansion (CTE) has a two-dimensional inhomogeneity (dCTE) distribution profile averaged over a thickness of the blank, a maximum inhomogeneity (dCTEmax) of less than 5 ppb/K being defined as a difference between a CTE maximum value and a CTE minimum value,
A method for producing a blank from titanium-doped silica glass for a mirror substrate for use in EUV lithography, the blank comprising a surface portion configured to be provided with a reflective film and having an optically used area (CA) over which a coefficient of thermal expansion (CTE) has a two-dimensional inhomogeneity (dCTE) distribution profile averaged over a thickness of the blank, a maximum inhomogeneity (dCTEmax) of less than 5 ppb/K being defined as a difference between a CTE maximum value and a CTE minimum value,
A method for producing a blank from titanium-doped silica glass for a mirror substrate for use in EUV lithography,
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
From the US filing history. Foreign family members aren’t listed.
Re-forming shaped glass: re-forming tubes or rods
By sintering, e.g. by cold isostatic pressing of powders and subsequent sintering, by hot pressing of powders, by sintering slurries or…: for the…
By gas- or vapour- phase reaction processes: thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering
By gas- or vapour- phase reaction processes: means for changing or stabilising the shape or form of the shaped article or deposit
About 8 years 8 months of term left · ends 24 Jun 2035 (estimated)
In one embodiment, the present invention relates to a blank made of titanium-doped silica glass for a mirror substrate for use in EUV lithography, with a surface portion to be provided with a reflective film and having an optically used area CA over which the coefficient of thermal expansion CTE has a two-dimensional dCTE distribution profile averaged over the thickness of the blank with a maximum inhomogeneity dCTEmax of less than 5 ppb/K defined as a difference between a CTE maximum value and a CTE minimum value.
Furthermore, in one embodiment, the present invention relates to a method for producing such a blank from titanium-doped glass (quartz glass) having a high silicic-acid content for a mirror substrate for use in EUV lithography.
In EUV lithography, highly integrated structures with a line width of less than 50 nm are produced by means of microlithographic projection devices. Use is here made of working radiation from the spectral range between 10 nm and 121 nm, which is also called EUV range (extreme ultraviolet light, also known as “soft X-ray radiation”). The typical operating wavelength in EUV lithography is 13 nm at the moment.
The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.
In the drawings:
FIG. 1 shows a dCTE distribution profile of a SiO2—TiO2 blank with a round cross-section in a false-color representation (in gray values) together with a gray value scale (in ppb/K);
A soot body doped with about 8% by wt. of TiO2 is produced preferably with the help of the OVD method by flame hydrolysis of octamethylcyclotetrasiloxane (OMCTS) and titanium isopropoxide [Ti(OiPr)4] as starting substances for the formation of SiO2—TiO2 particles.
The soot body is dehydrated at a temperature of 1150° C. in a heating furnace with a heating element of graphite under vacuum. The dehydration treatment preferably ends after 2 hours.
The soot body dried in this way is subsequently vitrified in a sintering furnace at a temperature of about 1500° C. under reduced pressure (10−2 mbar) into a transparent blank consisting of TiO2—SiO2 glass. The mean OH content of the glass is about 170 wt. ppm.