Thin Film Mainly Comprising Titanium Oxide, Sintered Sputtering Target Suitable for Producing Thin Film Mainly Comprising Titanium Oxide, and Method of Producing Thin Film Mainly Comprising Titanium Oxide

Abstract

Provided is a thin film mainly comprising titanium oxide, wherein the thin film comprises components of Ti, Ag and O and contains 29.6 at % or more and 34.0 at % or less of Ti, 0.003 at % or more and 7.4 at % or less of Ag, and oxygen as the remainder thereof, and O/(2Ti+0.5Ag) as a ratio of oxygen to metals is 0.97 or more. This invention aims to provide a thin film mainly comprising titanium oxide having a high refractive index and a low extinction coefficient, a sintered sputtering target mainly comprising titanium oxide suitable for producing the thin film, and a method of producing a thin film mainly comprising titanium oxide. This invention also aims to provide a thin film that has superior transmittance, minimally deteriorates in reflectance, and is useful as an interference film or a protective film for an optical information recording medium. It is also possible to apply this film to a glass substrate; that is, which can be used as a heat reflective film, an antireflective film, and an interference filter.

1 - 7 . (canceled) 
     
     
         8 . A sintered sputtering target suitable for producing a thin film mainly comprising titanium oxide, wherein the target comprises components of Ti, Ag and O, contains the respective components at a composition ratio of (TiO 2-m ) 1-n Ag n  (provided 0≦m≦0.5, and 0.0001≦n≦0.2), and has a specific resistance of 10 Ωcm or less. 
     
     
         9 . The sintered sputtering target according to  claim 8  suitable for producing a thin film mainly comprising titanium oxide, wherein the target comprises components of Ti, Ag and O, contains the respective components at a composition ratio of (TiO 2-m ) 1-n  (provided 0≦m≦0.5, and 0.01≦n≦0.2), and has a specific resistance of 10 Ωcm or less. 
     
     
         10 . The sintered sputtering target according to  claim 9 , wherein an average grain size of Ag phase existing in the sintered sputtering target is 15 μm or less. 
     
     
         11 . A method of producing a thin film mainly comprising titanium oxide, wherein a sintered sputtering target, which comprises components of Ti, Ag and O, contains the respective components at a composition ratio of (TiO 2-m ) 1-n Ag n  (provided 0≦m≦0.5, and 0.0001≦n≦0.2), and has a specific resistance of 10 Ωcm or less, is used to perform sputtering under an argon gas atmosphere without oxygen or with 0.1 to 16% of oxygen, whereby formed on a substrate is a thin film which contains 29.6 at % or more and 34.0 at % or less of Ti, 0.003 at % or more and 7.4 at % or less of Ag, and oxygen as the remainder thereof, and in which O/(2Ti+0.5Ag) as a ratio of oxygen to metals is 0.97 or more. 
     
     
         12 . A method of producing a thin film mainly comprising titanium oxide according to  claim 11 , wherein deposition is performed by way of DC sputtering and on oxygen gas ratio in the sputtering atmosphere is represented in b (%), the oxygen gas ratio is adjusted to be in a range of 0<b≦83.3n−0.17 when the composition ratio n of Ag in the sputtering target is 0.0001≦n≦0.01, and the oxygen gas ratio is adjusted to be in a range of 17n−0.17≦b≦83n−0.17 when the composition ratio n of Ag is 0.01≦n≦0.2. 
     
     
         13 . A method of producing a thin film mainly comprising titanium oxide according to  claim 11 , wherein sputtering is performed by adjusting the oxygen gas ratio b to be b=0% when the composition ratio m is in a range of 0≦m≦0.05 and the composition ratio n of Ag is 0.0001≦n≦0.01. 
     
     
         14 . A thin film mainly comprising titanium oxide obtained by the method of producing a thin film according to  claim 11 . 
     
     
         15 . The thin film mainly comprising titanium oxide according to  claim 14 , wherein a refractive index in a wavelength region from 400 to 410 nm is 2.6 or more, and an extinction coefficient in a wavelength region from 400 to 410 nm is 0.1 or less. 
     
     
         16 . The thin film mainly comprising titanium oxide according to  claim 15 , wherein O/Ti as a ratio of oxygen to Ti is 2 or more. 
     
     
         17 . The thin film mainly comprising titanium oxide according to  claim 16 , wherein an extinction coefficient in a wavelength region from 400 to 410 nm is 0.03 or less. 
     
     
         18 . The thin film mainly comprising titanium oxide according to  claim 17 , wherein the thin film is an interference film or a protective film. 
     
     
         19 . The thin film mainly comprising titanium oxide according to  claim 18 , wherein the thin film forms part of an optical recording medium. 
     
     
         20 . The thin film mainly comprising titanium oxide according to  claim 14 , wherein O/Ti as a ratio of oxygen to Ti is 2 or more. 
     
     
         21 . The thin film mainly comprising titanium oxide according to  claim 14 , wherein an extinction coefficient in a wavelength region from 400 to 410 nm is 0.03 or less. 
     
     
         22 . The thin film mainly comprising titanium oxide according to  claim 14 , wherein the thin film is an interference film or a protective film. 
     
     
         23 . The thin film mainly comprising titanium oxide according to  claim 22 , wherein the thin film forms part of an optical recording medium. 
     
     
         24 . The sintered sputtering target according to  claim 8 , wherein an average grain size of Ag phase existing in the sintered sputtering target is 15 μm or less.