| 摘要 |
PURPOSE: To decrease RDS-on for the use of a high voltage by providing an non-uniform low concentration dope drift area for increasing impurity concentration from a gate edge to a contact in a drain. CONSTITUTION: An (n) channel LDD device having a cross-section in which a low concentration dope drift area 35 is stepwisely doped is constituted. The impurity concentration of the LDD area 35 of this field effect transistor is gradually increased from No1 -at a gate edge through plural stages (k) to Nl -at a drain contact 36. Generally, the impurity concentration in the LDD area Nk - just close to a drain is made adjacent to impurity concentration N+ in a drain area 33. That is, the values of the N1 -and Nk -are respectively set to 1×10<-12> cm<-3> and 4×10<-12> cm<-3> .
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