| 摘要 |
PURPOSE:To obtain the buried layer with flat surface for the titled device by a method wherein, when an insulator buried layer is formed in a concavity provided on a semiconductor substrate, an Si3N4 layer is coated on the whole surface, and after the cubic volume of the above has been expanded by plasma anodic oxidation, the surface layer part is removed by etching. CONSTITUTION:An Al2O3 film 7, which is anti-anodic oxidizing agent, is coated on the Si substrate 6, a resist layer 8 is covered on an element forming region, the exposed part of the film 7 is removed by performing a reactive ion etching, wherein CF4 gas is used, using the resist layer 8 as a mask, and, at the same time, a concavity 9 is formed on the substrate 6. Then, the layer 8 is removed, an Si3N4 layer 10 of the thickness approximately one half of the depth of the concavity 9 is coated on the whole surface, and the thickness of the layer 10 is doubled approximately by performing plasma anodic oxidization on the layer 10. Thus, the layer 10 is converted to a thick SiO2 layer 11, exluding the part located above the layer 7, whereon the layer 10 remains in the form of Si3N4 layer 12. Subsequently, the layer 12 is removed by etching, and an etching is also performed on the layer located inside the concavity 9, thereby enabling to obtain the insulated buried layer 11 of flat surface. |
