Optical functional film and method for producing the same

1. An optical functional film comprising a siliceous material, wherein a refractive index n a of one surface A of said optical functional film to light is larger than a refractive index n b of the other side surface B to light, and the refractive index to light gradually decreases from said surface A to said surface B and wherein when a refractive index of a medium X coming into contact with said surface A is n x and a refractive index of a medium Y coming into contact with said surface B is n y , the relation

n y <n b <n a <n x

is satisfied and wherein the optical functional film is manufactured by the steps comprising a first layer forming step which comprises coating a composition comprising a polysiloxane and a solvent on a substrate and performing insolubilizing treatment by heating of the surface to form the first layer; a second layer forming step which comprises coating a composition comprising a polysiloxane that is different from said polysiloxane and a solvent that is identical to or different from said solvent on the surface of said first layer to form the second layer; and a heating step of heating to cure at 150° C. or higher said first layer and said second layer, wherein the contacting parts of said first layer and said second layer are compatibilized such that there is no interface between the first layer and the second layer caused by said first layer and second layer having different refractive indices and the compatibilizing is performed by a prebaking or a heat-curing between after starting said second layer forming step and until ending said heating step.

2. The optical functional film according to claim 1 , wherein said siliceous material is formed from a polysiloxane having a silanol group, as a raw material.

3. The optical functional film according to claim 2 , wherein said polysiloxane is obtained by hydrolyzing and condensing a silane compound of the general formula (1) in the presence of an acidic or basic catalyst:

R ll n Si(OR 12 ) 4-n   (1)

wherein

R 11 is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, in which any methylene may be replaced with oxygen, or an aryl group having 6 to 20 carbon atoms, in which any hydrogen may be replaced with fluorine,

R 12 is a alkyl group having 1 to 6 carbon atoms, and n is 0, 1 or 2.

4. The optical functional film according to claim 2 , wherein said polysiloxane is a composite of silicon oxide nanoparticles and a siloxane polymer, which is obtained by reacting a siloxane polymer having a silanol group, a silane monomer having a silanol group or mixture thereof with silicon oxide nanoparticles having a hydroxyl group or an alkoxy group on the surface in a mixed solvent of an aqueous solvent and an organic solvent in the presence of phase transfer catalyst.

5. The optical functional film according to claim 2 , wherein said polysiloxane is a composite of metal oxide nanoparticles and a siloxane polymer, which is obtained by reacting a siloxane polymer having a silanol group, a silane monomer having a silanol group or mixture thereof with metal oxide nanoparticles having a hydroxyl group or an alkoxy group on the surface in a mixed solvent of an aqueous solvent and an organic solvent in the presence of phase transfer catalyst.

6. The optical functional film according to claim 5 , wherein said metal oxide nanoparticles are represented by the following general formula (3):

M x O y (OR 3 ) z   (3)

wherein

M is an element selected from the group consisting of Ti, Zr, Eu, Zn, B, Al, Ta and Hf,

R 3 is hydrogen, or a Ci to Cio alkyl or alkenyl group, and

2y+z=x·[valence of M] is satisfied.

7. The optical functional film according to claim 1 , wherein said insolubilizing treatment is performed by a step selected from the group consisting of heat curing, UV ozone irradiation and surface treatment by tetramethylammonium hydroxide solution.

8. A semiconductor device, comprising said optical functional film according to claim 1 on a substrate surface.

9. A semiconductor device according to claim 8 , wherein said surface A of the optical functional film comes into contact with said substrate surface.

10. The semiconductor device according to claim 9 , wherein a refractive index n s of said substrate is larger than said refractive index n a of said surface A.

11. The optical functional film according to claim 1 , wherein the polysiloxane comprises a reactive group excluding silanol group or alkoxyl group is 10 mol % or less based on the total number of hydrogen or substituents binding to the silicon atom.