| 摘要 |
PURPOSE:To integrate a multipurpose device by controlling the thickness and the impurity density on the same semiconductor substrate to form a composite epitaxial layer. CONSTITUTION:An Si substrate 12 is partly etched to form a buried collector 15, the thickness and the density are controlled for high voltage resistance by a controller 16, an SiO2 mask 13 is formed, and is epitaxially formed. After the film 13 is removed, an isolation layer 17 and the second buried collector 18 are formed, the thickness and the density are controlled for high speed switching, an epitaxial layer 19 is formed, and an isolation layer 20 is formed. Base 23, 25 and emitter 24, 26 are respectively formed on wells 21, 22. A semiconductor device having two types of features can be formed and integrated on one chip. |
