MEMORY DEVICE WITH VERTICAL TRANSISTOR AND FABRICATION METHOD THEREOF

摘要

A method for fabricating a vertical transistor. At least one deep trench is formed in a silicon substrate. A conductive structure and a trench top insulator are successively formed in the deep trench, in which the conductive structure comprises a first doping region and the trench top insulator is below the surface of the silicon substrate. An epitaxial silicon layer is formed on the surface of the silicon substrate. Ion implantation is performed in the epitaxial silicon layer to form a second doping region therein. A gate structure is formed on the trench top insulator, protruding from the surface of the epitaxial silicon layer and adjacent to the sidewalls of the epitaxial silicon layer and the deep trench. A capping layer is formed on the epitaxial silicon layer. The invention also discloses a memory device with a vertical transistor and a method for fabricating the same.