Semiconductor device with integrated junction field effect transistor and associated manufacturing method

A method for manufacturing a semiconductor device, comprising:

• preparing a substrate of a first conductivity type having a drain region doped at least adjacent a first surface of the substrate;
• forming a first source region of the first conductivity type and a second source region of the first conductivity type in the substrate, wherein the first source region is formed adjacent a second surface of the substrate opposite to the first surface, and wherein the second source region is formed below the first source region and separated from the first source region;
• forming a gate trench of a gate region in the substrate such that the gate trench is disposed closely next to or in adjoining neighbor to the first source region;
• forming a first sidewall body region of a second conductivity type below or underneath the first source region to separate the first source region from the second source region;
• forming a link region of the second conductivity type such that the link region and the gate trench are respectively disposed at a first side of the first source region and a second side of the first source region, the first side of the first source region being opposite to the second side of the first source region;
• forming a gate insulation layer to coat and line sidewalls and a bottom of the gate trench;
• and
• using a gate conductive material to fill the gate trench.