| 摘要 |
PURPOSE: A device isolation film forming method of a semiconductor device is to prevent an electrical deterioration by suppressing an electrical concentration at the edge of a field region. CONSTITUTION: A pad heat oxide film and a pad nitride film are formed on a silicon substrate(11). After a mask process of a device isolation region, a trench is formed in the silicon substrate by selectively etching the pad nitride film, the pad heat oxide film, and the silicon substrate. The trench is buried by forming an oxide film and a buried insulation film(16) in the trench. The buried insulation film is then polished by using a chemical mechanical polish to expose the nitride film. After removing the exposed nitride film by a wet etching, a screen nitride film is formed on an upper portion of the whole structure. A first N well(18) and a second N well(19) are formed on a predetermined region of the silicon substrate by ion injecting an N-type impurity thereinto. A P well(20) is then formed on a predetermined region of the silicon substrate by ion injecting a P-type impurity thereinto besides the second N well region. An N channel and a P channel(22) are then formed on a predetermined region the silicon substrate by ion injecting the P-type impurity thereinto. Finally, a gate oxide film(23) and a gate electrode are formed on an upper portion of the whole structure by removing the screen nitride film and the pad oxide film by the wet etching.
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