Method for manufacturing lining oxide layer of shallow trench isolation (STI)

The invention provides a method for manufacturing a lining oxide layer of shallow trench isolation (STI). The method comprises the following steps of: raising the temperature of a chamber to the temperature, namely a first temperature, for oxidizing silicon; introducing a first flow of oxygen into the chamber when the temperature reaches the first temperature; continuously raising the temperatureof the chamber to a second temperature, reducing the flow of the oxygen to a second flow, and introducing nitrogen into the chamber; and reducing the temperature of the chamber and continuously introducing the nitrogen and the second flow of oxygen. By the method, the defect of a hole at a corner on the surface of a trench of a substrate is overcome.