Composite substrate material and process for producing the same

Abstract

A functional film, which has photo-catalytic effects, is overlaid on a surface of each of at least two substrate materials. The functional film, which has been overlaid on the surface of each of the substrate materials, is exposed to light having a wavelength falling within an absorption wavelength range of the functional film. The substrate materials are then bonded to each other with the functional films, which have been exposed to the light, intervening between the substrate materials. The functional film may be a film containing TiO 2 , and the light irradiated to the functional film may be ultraviolet light. In cases where a film other than the functional film is also overlaid on the surface of each of the substrate materials, the functional film is formed as a top layer.

1 - 4 . (canceled)  
     
     
         5 . A composite substrate material produced with a process comprising the steps of: 
 i) overlaying a functional film, which has photo-catalytic effects, on a surface of each of at least two substrate materials, wherein at least two of the substrate materials are non-transparent;    ii) exposing the functional film, which has been overlaid on the surface of each of the at least two substrate materials, to light having a wavelength falling within an absorption wavelength range of the functional film, and    iii) bonding the at least two substrate materials to each other with the functional films, which have been exposed to the light, intervening between the at least two substrate materials.    
     
     
         6 . A composite substrate material, comprising at least two substrate materials bonded to each other with functional films, which have photo-catalytic effects, intervening between the at least two substrate materials, wherein at least two of the substrate materials are non-transparent.  
     
     
         7 . The composite substrate material as defined in  claim 5  or  6  wherein each of the functional films is a film containing TiO 2 .  
     
     
         8 . The composite substrate material as defined in  claim 5  or  6  wherein each of the functional films also acts as an anti-reflection film.  
     
     
         9 . The composite substrate material as defined in  claim 5  or  6  wherein each of the functional films is formed thin such that each of the functional films is optically negligible.  
     
     
         10 . The composite substrate material as defined in  claim 5  or  6 , wherein at least two of the substrate materials are silicon wafers.