Field effect transistor and method of its manufacture

• Main Author: BRIAN SZE-KI MO,DUC CHAU,STEVEN SAPP
• Format: Patent
• Language: English
• Published: 19.09.2007
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

A field effect transistor comprising: a semiconductor substrate having dopants of a first conductivity type; a gate-forming trench extending from a surface of the substrate a predetermined depth into the semiconductor substrate; a doped well having dopants of a second conductivity type opposite to the first conductivity type and extending from the surface of the substrate into the semiconductor substrate to form a well junction at a first depth that is shallower than the predetermined depth of the trench; a pair of doped source regions having dopants of the first conductivity type and positioned on opposite sides of the trench extending from the surface of the substrate into the semiconductor substrate along the length of the trench of the trench to form a source junction at a second depth; and a doped heavy body region having dopants of the second conductivity type formed inside the doped well and positioned between a pair of gate-forming trenches, the doped heavy body region forming a heavy body junction at a depth that is deeper than the source junction and shallower than the doped well, and having a region of peak concentration occurring at a depth below the surface of the substrate; wherein the depth of the heavy body region relative to the depths of the well and trench is selected so that a peak electric fields, when voltage is applied to the transistor, will be spaced from the trench.