Methods of implanting ions into different active areas to provide active areas having increased ion concentrations adjacent to isolation structures

摘要

Active areas of integrated circuits can be formed by implanting first ions into a first active area of a substrate adjacent to an isolation structure in the substrate and between a source and a drain region of the integrated circuit to provide a first concentration of ions in the first active area. Second ions are implanted into the first active area and a second active area of the substrate adjacent to the first active area and spaced-apart from the isolation structure on the substrate to provide a second concentration of ions in the second active area and a third concentration of ions in the first active area that is greater than the first and second concentrations. As a result, the level of ion concentration can be higher at the edge of an active channel region than at the center of the channel. The increased concentration of ions in the active area adjacent to the side wall of the trench may reduce a current between the source and drain regions of the transistor when voltage that is less than a threshold voltage of the transistor is applied to the gate electrode of the transistor. Thus, a reduction in the threshold voltage of the transistor can be inhibited. Integrated circuit transistors are also disclosed.