| 摘要 |
PURPOSE:To realize high integration density of an MOS semiconductor device by narrowing the width of element separation region. CONSTITUTION:A large groove having the width 8 of aperture which is made smaller than the depth 9 is formed in rectangular or in the form similar to rectangular by the reactive ion etching. The numeral 10 is a mask material such as photo resists. The groove formed on a silicon substrate is filled with a silicon oxide film 11 in the thermal oxidation process. When an oxidation mask material is composed of an alumina film, the anode oxidation method is used. In the method of this invention, since the silicon oxide film filling the groove is almost satisfied by oxidation in both sides of groove since the depth 9 of groove formed on the silicon substrate is made larger than the width 8 of the aperture. Therefore, since the oxidation time for forming a silicon oxide film for element separation can be sufficiently curtailed, generation of bird's beak is very rare even in case the silicon oxide film is formed as a buffer. For example, in case the width of aperture is 0.3mum, the width of element separation region can be set to 0.6mum or less. This value is negligibly small. |
