| 摘要 |
PURPOSE:To flatten the surface of a groove isolation section with excellent reproducibility by flattening the surface of polysilicon, to which a groove is buried, by using an etching liquid, an etching rate thereof changes to polysilicon containing boron in high concentration and non-doped polysilicon. CONSTITUTION:A groove is formed to the main surface of an silicon substrate 20 through anisotropic dry etching, and an insulating film 21 is formed onto an silicon surface by a thermal oxide film. A polysilicon film 22 containing boron is shaped only on the side wall section of the groove. A non-doped polysilicon film 23 is shaped, the non-doped polysilicon film 23 in a groove section is boron-doped through heat treatment, and a boron-diffusing region 24 in high concentration is formed up to the position of approximately the surface of the silicon substrate 20. Only the non-doped polysilicon film is removed selectively by an etching solution mainly comprising hydrazine heated at 60 deg.C, thus obtaining extremely stable flatness. |
