| 摘要 |
PURPOSE:To eliminate the causing of the dispersion of a threshold voltage and also, to make higher the withstand voltage of an MOS transistor by a method wherein a shielding region is formed in such a ways as to encircle the source region and moreover, low-concentration regions of the same conductive type are formed in contact with the source region and the drain region respectively. CONSTITUTION:A P-type shielding region 6 is formed in such a way as to encircle a source region 4, and a low-concentration source region 8 and a low- concentration drain region 9 are formed in contact with the source region 4 and a drain region 5 respectively. In this device, when a voltage is impressed between the source region 4 and the drain region 5, depletion layers extend to the directions of the Si substrate 1 and the low-concentration drain region 9 as shown in an impurity concentration distribution B-B' and the electric field is relaxed. Therefore, the BVDS can be made higher. Moreover, as the shielding region 6 is formed on the periphery of the source region 4, the BVSB can be made higher.
|
