An object of the present invention is to provide a semiconductor device including an insulating layer with a high dielectric strength voltage, a low dielectric constant, and low hygroscopicity. Another object of the present invention is to provide an electronic appliance with high performance and high reliability, which uses the semiconductor device. An insulator containing nitrogen, such as silicon oxynitride or silicon nitride oxide, and an insulator containing nitrogen and fluorine, such as silicon oxynitride added with fluorine or silicon nitride oxide added with fluorine, are alternately deposited so that an insulating layer is formed. By sandwiching an insulator containing nitrogen and fluorine between insulators containing nitrogen, the insulator containing nitrogen and fluorine can be prevented from absorbing moisture and thus a dielectric strength voltage can be increased. Further, an insulator contains fluorine so that a dielectric constant can be reduced.