| 摘要 |
PURPOSE:To lower production cost by a method wherein first impurities are introduced by making use of a patterned oxidation-resistant film as a mask, second impurites are then introduced by using a resist mask and an impurity diffusion layer is changed to a buried layer. CONSTITUTION:N-type impurities are introduced into the surface part of silicon by using a resist mask or by making use of a patterned SiN film 3 as a mask; after that, P-type impurities are introduced into the surface part of silicon under the SiN film 3 by using a resist mask; in addition, the N-type and P-type impurities are diffused and activated by a selective oxidation treatment; a plurality of impurity diffusion regions 9a, 9b and 9c are formed; after that, an epitaxial layer 12 is formed on a silicon substrate 1; the impurity diffusion regions 9a, 9b and 9c are changed respectively to buried layers 13a, 13b and 13c. A plurality of differences in level 11a and 11b are formed on the face of silicon by using a field oxide film formed at the selective oxidation treatment. For example, the difference in level 11a out of them, i.e., a difference in level 14a, can be utilized as a difference in level for alignment mask use. |
