Some possible applications of three-dimensional (3-0)ivl0S transistors arc proposed in Ihis study focusing on processint: techniques to real ize tall silicon bemn with I'cry lligh aspect-ratio. overlaying gate fonnation. and 3-D plasma doping into the tall beam. In addition to tlIC possibility of the techniques. limitations to further scaling are discusscd ill this sludy. l. IntnHluction Threc-dimcnsional (:'.-0) transistors re ccnt l�' pro poscd 1 -J ) haH: focllsed on their miniaturization in response to Ihe requirement for [1II1her scaling of MOS .ransistor. While. an MOS transistor of 5 nm in gate icngth 11,15 bcen devclopcd�) [IS ,1 conventional planar one cvell though its perronn:lI1ce does not descrye its milliature size. Besides the transistor scaling. there exists anothcr application of 3-D tr;lT1sis\or ror powcr transistor in tegrated ill LSI. Since the power transistor consumes ;1 101 of planar area responding to power requirement IXlrt icularly ill area-consciolls LSI, more power in les s are;1 musl be cicsirable. Thus. somc possible application of 3-D MOS transistor \\'ith high silic on bcam which is named beam-channel transistor. BCTS-7) is proposed in this study. As the proposcd tr