According to the present invention, there are provided a surface-modified inorganic substance obtained by performing surface modification on a inorganic nitride by using an aldehyde compound such as a compound represented by General Formula I and a resin composition containing the surface-modified inorganic substance and a monomer having a group selected from the group consisting of an oxetanyl group, an oxiranyl group, and a (meth)acrylate group. By using the surface-modified inorganic substance or the resin composition, it is possible to provide a thermally conductive material having excellent thermal conductivity and a device having high durability.

Z.sub.ZX.sub.XCHOGeneral Formula I

(In the formula, Z.sub.Z represents a group selected from the group consisting of an amino group, a thiol group, a hydroxyl group, an isocyanate group, a carboxyl group, a carboxylic acid anhydride group, an oxetanyl group, an oxiranyl group, a (meth)acrylate group, and a hydrogen atom, and X.sub.X represents a divalent linking group.)

A carbon-coated thermal conductive material includes a coating layer comprising amorphous carbon on a surface of a thermal conductive material, wherein the thermal conductive material comprises a metal oxide, a metal nitride, a metal material, or a carbon-based material having a thermal conductivity of 10 W/mK or greater, the amorphous carbon is derived from carbon contained in an oxazine resin, a ratio of a peak intensity of a G band to a peak intensity of a D band is 1.0 or greater when the amorphous carbon is measured by Raman spectroscopy, an average film thickness of the coating layer is 500 nm or less, and a coefficient of variation (CV value) of a film thickness of the coating layer is 15% or less.

A silicon-containing oxide-coated aluminum nitride particle including an aluminum nitride particle and a silicon-containing oxide coating covering the surface of the aluminum nitride particle. The content of carbon atoms is less than 1000 ppm by mass, and an Si/Al atom ratio of the surface as measured by AES analysis is 0.29 or more and 5.0 or less. In another aspect, the coverage of the silicon-containing oxide coating covering the surface of the aluminum nitride particle as measured by LEIS analysis is 15% or more and 100% or less.

A carbon-coated thermal conductive material includes a coating layer comprising amorphous carbon on a surface of a thermal conductive material, wherein the thermal conductive material comprises a metal oxide, a metal nitride, a metal material, or a carbon-based material having a thermal conductivity of 10 W/mK or greater, the amorphous carbon is derived from carbon contained in an oxazine resin, a ratio of a peak intensity of a G band to a peak intensity of a D band is 1.0 or greater when the amorphous carbon is measured by Raman spectroscopy, an average film thickness of the coating layer is 500 nm or less, and a coefficient of variation (CV value) of a film thickness of the coating layer is 15% or less.

An inorganic filler included in an epoxy resin composition includes a coating layer formed on a surface thereof, and the surface of the coating layer includes at least two elements selected from the group consisting of C, N and O.

An aluminum nitride powder according to the present invention has an average particle size of 5 to 50 m and an oxygen content of 0.5% by mass or less, has polyhedral particles having at least two smooth surfaces a under observation with a scanning electron microscope at 500 magnification, in which for the polyhedral particles with a major axis (L) of 5 m or more, the average value of the ratio (L/D) of the major axis (L) to the minor axis (D) is within the range of 1 to 1.4. According to the present invention, an aluminum nitride powder having high thermal conductivity when filled in a resin to obtain a resin composition, and good fluidity, can be provided.

The purpose of the present is to provide a modified AlN source for suppressing downfall defects. This manufacturing method of a modified aluminum nitride source involves a heat treatment step for heat treating an aluminum nitride source and generating an aluminum nitride sintered body.