| 摘要 |
<p>The method comprises a step of forming a three-layer film consisting of a first silicon nitride film (102), a first silicon oxide film (103) and a second silicon nitride film (104) on a portion of a silicon substrate (101), and further forming a third silicon nitride film (106) on the side walls of the three-layer film, a step of forming a first groove having nearly vertical side walls in the exposed silicon substrate (101) by etching, and filling the first groove with a silicon oxide film (108), and a step of removing the second and third silicon nitride films (104,106) and forming a second groove (111) having side walls that are nearly perpendicular to the exposed silicon substrate (101). Therefore, the second groove (111) that serves as a trench is formed at an end of the silicon oxide film (108) in the field region (107) by the self-alignment to come in direct contact with an element-forming region (115). Further, the width of groove becomes equal to the width of the third silicon nitride film (106) which is constant, and parasitic capacitance becomes the smallest between the collector and substrate.</p> |
