NOVELTY - Formation (m1) of a ceramic silicon oxide type coating involves forming a coating (c1) comprising an organohydrogensiloxane-hydrogensiloxane copolymer, on the surface of an inorganic base material; and then heating the coated inorganic base material to a high temperature in an inert gas or an oxygen gas-containing inert gas (oxygen gas less than 20 vol.%) to convert the coating into a ceramic silicon oxide type coating.    USE - For formation of a ceramic silicon oxide type coating on inorganic base material which is useful in a semiconductor device (i.e. a thin film solar battery) (claimed). The semiconductor device also includes thin film semiconductor devices such as thin film transistors (TFTs) for reflection-type liquid crystal display devices, thin film electroluminescent display elements and devices, and thin film lithium batteries.    ADVANTAGE - The semiconductor device comprising at least a semiconductor layer formed on the ceramic silicon oxide type coating on a metal substrate, exhibits an excellent reliability and durability and can take the form of a thin film.    DETAILED DESCRIPTION - Formation (m1) of a ceramic silicon oxide type coating involves forming a coating comprising an organohydrogensiloxane-hydrogensiloxane copolymer of formula (HRSiO2/2)n(HSiO3/2)m (I), on the surface of an inorganic base material; and then heating the coated inorganic base material to a high temperature in an inert gas or an oxygen gas-containing inert gas (oxygen gas less than 20 vol.%) to convert the coating into a ceramic silicon oxide type coating.    R=monovalent hydrocarbyl group selected from 1-10C alkyl or 6-10C aryl;    n=0.01-0.80;    n+m=1.    INDEPENDENT CLAIMS are included for the following:    (1) an agent for forming a ceramic silicon oxide type coating, comprising either an organohydrogensiloxane-hydrogensiloxane copolymer (I); or the copolymer (I) and an organic solvent in a quantity required for the dissolution or dilution of the copolymer (I), and can be converted into a ceramic silicon oxide type coating by heating to high temperature in an inert gas or an oxygen gas-containing inert gas (oxygen gas less than 20 vol.%); and    (2) a semiconductor device comprising at least a semiconductor layer which is formed on the ceramic silicon oxide type coating of a metal substrate having on its surface a ceramic silicon oxide type coating obtained by the method (m1).