A lightly doped source and a lightly doped drain are formed at a region which is adjacent to a heavily doped source and a heavily doped drain of FET and all or a part of which is under a gate electrode. In the lightly doped source and the lightly doped drain, an effective impurity atom concentration...http://www.google.de/patents/US5362982?utm_source=gb-gplus-sharePatent US5362982 - Insulated gate FET with a particular LDD structure
