| 摘要 |
PURPOSE: The method mixes a retrograde well(17, 25) and a trench isolation method. The device has the advantages of process time reduction and chip size scale-down and the large integration with the trench isolation method by self align trench method. CONSTITUTION: The semiconductor device comprises an active region and an isolation region formed on a semiconductor substrate(11), and the retrograde well formed on the bottom of the semiconductor substrate. The retrograde well comprises plural dopant regions(25a, 25b, 25c) formed uniformly with different depth each other as dopants are implanted in multistage with different energy before forming the isolation region. The device has a uniform characteristics of uniform well profile by forming the retrograde well before forming the isolation region.
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