| 摘要 |
PROBLEM TO BE SOLVED: To perform a perfect depletion type operation and to suppress the decline of a threshold voltage. SOLUTION: This semiconductor device comprises a first insulation layer 2, a semiconductor layer formed on the upper surface side of the first insulation layer 2, and a second insulation layer 7 formed on the upper surface side of the semiconductor layer. The semiconductor layer has a channel region (5 and 6) and source/drain regions 3 formed in a region outside the channel region (5 and 6). The channel region comprises a low impurity concentration region 5 and a high impurity concentration region 6 which is formed in a region outside the low impurity concentration region 5 and has a higher impurity concentration than the low impurity concentration region. It is essentially important that the width of the high impurity concentration region 6 is not wider than 30 nm. If the width of the high impurity concentration is not wider than 30 nm, a perfect depletion type operation can be performed and, further, the decline of a threshold voltage can be suppressed. If the impurity concentration of the high impurity concentration region 6 is lower than 1/10 of the impurity concentration of source/drain regions at a position 30 nm inside the edge of the source/drain region, the perfect depletion type operation can be performed more efficiently and, further, the decline of the threshold voltage can be suppressed more effectively. |
