| 摘要 |
PURPOSE:To shrink a crystal lattice and to cancel the spreading of the crystal lattice with oxygen atoms by a method wherein a semiconductor layer is formed on the insulative substrate and after oxygen is ion-implanted in the semiconductor layer, atoms smaller than the constituent atom of the semiconductor layer are ion-implanted and a heat treatment is performed. CONSTITUTION:A semiconductor layer 2, which is a silicon layer, is formed on a sapphire 1 and oxygen is ion-implanted in the silicon layer 2. Subsequently, carbon being constituted of atoms with a radius smaller than that of the constituent atom of the silicon layer 2 is ion-implanted and a heat treatment is performed in an atmosphere of nitrogen to improve the crystallizability of the silicon layer 2. By implanting oxygen in the silicon layer 2, Al is fixed on the interface between the silicon layer 2 and the sapphire substrate 1 according to the chemical reaction of the oxygen atoms to the Al and the oozing of Al can be suppressed. By this way, the fluctuation of the threshold value of the MOS transistor, which is formed in the silicon layer, can be restrained and the speeding-up property, which is one of the characteristics of the MOS element, can be utilized usefully even though the silicon layer is microscopically formed. |
