| 摘要 |
PURPOSE:To form a thinner epitaxial layer on a substrate having one conductive type, by depositing the epitaxial layer on the substrate and then repeating a heat oxidation process of oxidizing the layer to a predetermined thickness and an etching process of removing the oxidized silicon film for several times. CONSTITUTION:A p-type silicon epitaxial layer 2 is deposited on an n-type silicon substrate 1 to a thickness of 2.5Xm. The substrate is then kept at 1,000 deg.C and heat treated for 1hr within a heating surface supplied with oxygen which has been passed through 95 deg.C water,whereby an oxide film 3 of 3,750Angstrom is formed on the surface of the silicon substrate. The oxide film 3 is completely removed with an etching solution in which HF and NH4F are mixed in the volume ratio of 2:10, whereby the thickness of the epitaxial layer 21 on the silicon substrate is reduced. Repeating these processes of oxidization and of removing an oxide film 3 with the same etching solution, the thickness of the epitaxial layer on the silicon substrate can be further reduced. |
