| 摘要 |
PURPOSE:To make the gradient of the concentration of impurities gentler in a source region and a drain region in a thin film transistor of an LDD construction. CONSTITUTION:If phosphorus ion of a high concentration is shallowly implanted at an angle of 30 deg. from the side of a drain region 12b using a gate electrode 14 as mask, its peak can be indicated by a curve P. Next, phosphorous ion of medium concentration is implanted slightly deeply from the same angle of 30 deg., its peak can be indicated by a curve Q. Next, phosphorous ion of a low concentration is more deeply implanted from the same angle of 30 deg. and then its peak is indicated by a curve R. Also, at the side of source region 12a, the phosphorous ion implantation is performed 3 times with the angle of 150 deg.. Thereafter, the implanted impurities are activated by performing laser annealing at about 400 deg.C, and then the gradient of impurities concentration becomes gentler even though the diffusion of implanted impurities is not performed. |
