| 摘要 |
PURPOSE:To obtain a device having high injection efficiency and high performance by partially forming a high concentration layer by using focussed ion-beam technique. CONSTITUTION:In structure having a silicon substrate 11 and SiO212, a poly Si floating gate 13, SiO214, a poly Si control gate 15, an N<+> source 16 and a drain 17, boron ions are implanted by focussed ion beams, and a P type layer 18 in 10<17>cm<-3> surface concentration is formed. Impurity concentration in a channel region in a transistor can be brought to 1X10<16>cm<-3> or less by forming device structure so that an ion implantation layer shaped to one part of a channel and one part of a drain are superposed, and proper threshold voltage and high carrier mobility can be realized while the injection efficiency of carriers can be improved sufficiently even by applied voltage of approximately half conventional devices because of the presence of the high concentration region 18. |
