| 摘要 |
A buried collector layer (2) is formed on a semiconductor substrate (1). An epitaxial layer (4) is formed on the buried collector layer (2). A plurality of element separating trenches (11) of roughly the same depth and filled with an insulating material are formed in the epitaxial layer (4). When these trenches are formed deep enough to penetrate the buried collector layer to the semiconductor substrate, an impurity region of conductivity the same as that of the buried collector layer is formed at a predetermined position of the semiconductor substrate and adjoining to at least one bottom portion of a plurality of the trenches. Further, when a separation layer is formed on the semiconductor substrate and adjoining to the buried collector layer to separate the semiconductor device from another adjacent semiconductor device, at least one of a plurality of trenches is formed on a boundary surface between the buried collector layer and the separation layer. <IMAGE> |
