The present provides a semiconductor element and a forming method thereof. An offset spacer for CMOS transistors and a method of manufacture is provided. A gate electrode is formed on a substrate, and an offset mask layer is formed over the surface of the gate electrode and the substrate. The offset mask may be formed of an oxide layer and acts as a mask during implanting, such as pocket implants and lightly-doped drain implants. A second implant spacer may be formed on top of the offset mask layer adjacent the gate electrode, and another implant process may be performed to form deeply-doped drain regions. The semiconductor element and the forming method thereof reduce the time and cost spent in depositing and cleaning, besides, the usage of offset mask is controlled more easily. |