NOVELTY - Preparation of an inorganic substrate (I) having a thin silica type glass layer of 2H-9H pencil hardness, comprises: coating an inorganic substrate with a cyclic dihydrogenpolysiloxane (A) (that is liquid, has a weight-average molecular weight of 1500-1000000, and is composed of siloxane unit) and/or a hydrogenpolysiloxane (B) (that is liquid at 120degreesC, has a weight-average molecular weight of 500-1000000); and curing the coated (A) and/or the coated (B) to form a thin silica type glass layer of 2H-9H pencil hardness.    USE - (I) is for manufacturing: a semiconductor device (a thin solar battery) (claimed), for solar houses, image-forming equipment, portable telephones, computers displays, domestic appliances, office automation equipment, automobiles, aircrafts, space satellites and ships; reflection-type liquid crystal displays; electroluminescent displays; thin-film transistors of reflection-type liquid crystal displays; thin-film type lithium batteries; thin membrane solar batteries; and thin membrane transistor for reflection type liquid crystal displays and electroluminescent display.    ADVANTAGE - The process provides (I), which exhibits electrical insulating properties, flexibility, frost-resistant, high mechanical strength, resistance to chemicals and thermal resistance, where the thin silica type glass layer is free of cracks, tightly adheres to the surface of (I). (I) does not subject to changes, deterioration of properties and deformations even with exposure to high temperatures required for the formation of semiconductor layers, light-emitting layers and positive electrode layers. (I) has smooth surface even it has microscopic irregularities and holes. (I) provides the semiconductor device with a high reliability and durability.    DETAILED DESCRIPTION - Preparation of an inorganic substrate (I) having a thin silica type glass layer of 2H-9H pencil hardness, comprises: coating an inorganic substrate with a cyclic dihydrogenpolysiloxane (A) that is liquid at ambient temperature, has a weight-average molecular weight of 1500-1000000, and is composed of siloxane unit of formula (H2SiO2/2), and/or a hydrogenpolysiloxane (B) of formula ((H2SiO2/2)x (HSiO3/2)y (SiO4/2)x) that is liquid at 120degreesC, has a weight-average molecular weight of 500-1000000; curing the coated (A) and/or the coated (B) to form a thin silica type glass layer of 2H-9H pencil hardness.    x, y, z = mole concentrations.    Provided that 0.12less than or equal tox less than 1; 0less than or equal toyless than or equal to0.88; 0less than or equal tozless than or equal to0.3; y and z cannot be concurrently equal to 0; x+y+z = 1. INDEPENDENT CLAIMS are included for:    (1) the inorganic substrate (I) having a thin silica type glass layer of 2H-9H pencil hardness, where the thin silica type glass layer comprising a cured body of (A) and/or (B);    (2) a coating agent for (I) comprising: (A) and/or (B); or an organic solvent solution of (A) and/or (B); and    (3) a semiconductor device produced by forming at least a semiconductor layer on the thin silica type glass layer of (I).