| 摘要 |
The invention discloses a method of forming threshold voltage adjustment for MOS transistors. At first, a first oxide layer and a nitride layer are formed on a silicon substrate in sequence. Next, shallow trenches and active regions are formed by using photolithography and dry etching technology. A wet etching step is performed to remove part of the nitride layer, and then the first ion implantation for threshold voltage adjustment are performed. After accomplishing shallow trench isolations, the second ion implantation for threshold voltage adjustment are finally performed.
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