A multi-bridge-channel MOSFET (MBCFET) may be formed by forming a stacked structure on a substrate that includes channel layers and interchannel layers interposed between the channel layers. Trenches are formed by selectively etching the stacked structure. The trenches run across the stacked structure parallel to each other and separate a first stacked portion including channel patterns and interchannel patterns from second stacked portions including channel and interchannel layers remaining on both sides of the first stacked portion. First source and drain regions are grown using selective epitaxial growth. The first source and drain regions fill the trenches and connect to second source and drain regions defined by the second stacked portions. Marginal sections of the interchannel patterns of the first stacked portion are selectively exposed. Through tunnels are formed by selectively removing the interchannel patterns of the first stacked portion beginning with the exposed marginal sections. The through tunnels are surrounded by the first source and drain regions and the channel patterns. A gate is formed along with a gate dielectric layer, the gate filling the through tunnels and extending onto the first stacked portion.