Abstract: The present invention provides a thin film transistor including: a channel layer mainly containing a conductive oxide semiconductor; a pair of electrodes on the channel layer; and a protective film covering an exposed surface of the channel layer, exposed to the gap between the pair of electrodes. The protective film includes at least an oxygen transmission film in contact with the channel layer, and an oxygen disturbance film hardly transmitting oxygen in comparison with the oxygen transmission film, in this order from the channel layer side. A length of the oxygen disturbance film in a direction where the pair of electrodes face each other is equal to or larger than a value obtained by multiplying a width of the pair of electrodes in a direction orthogonal to the direction where the pair of electrodes face each other by 0.55.

Abstract: A method of forming a silicon oxide layer comprising initiating formation of a silicon oxide layer on a surface of a silicon layer by an oxidation method using wet gas at an ambient temperature at which no silicon atom is eliminated from the surface of the silicon layer, and then, forming the silicon oxide layer up to a predetermined thickness by an oxidation method using wet gas.

Abstract: A process for forming a silicon oxide film comprising:(a) heat treating a semiconductor substrate at a temperature of 1,150.degree. C. or higher under a 100% hydrogen gas atmosphere for a period of 10 to 600 minutes; and(b) forming a silicon oxide film on the semiconductor substrate by wet oxidation, followed by heat treating said silicon oxide film under an inert gas atmosphere containing a halogen element.

Abstract: An intermediate layer is formed on a portion which becomes a projecting portion of a step difference formed on a semiconductor substrate, a layer to be polished having a slower polishing rate than the intermediate layer is formed to cover intermediate layer and fill a recessed portion of the step difference, and then polishing is carried out over an area from this layer to be polished to the intermediate layer. Further, it is also possible to form a stopper layer having a slower polishing rate than the layer to be polished under the intermediate layer. In the polishing, a fluctuation of the rotational torque of the polishing machine of a predetermined value or more or an interference color may be used for detection of the end point of polishing.

Abstract: A process for forming a silicon oxide film comprising:(a) heat treating a semiconductor substrate at a temperature of 1,150.degree. C. or higher under a 100% hydrogen gas atmosphere for a period of 10 to 600 minutes; and(b) forming a silicon oxide film on the semiconductor substrate by wet oxidation, followed by heat treating said silicon oxide film under an inert gas atmosphere containing a halogen element.