Stacked Multi-Gate Structure And Methods Of Fabricating The Same

A semiconductor device, comprising:

• a substrate;
• a first transistor over the substrate, the first transistor including first channel layers and a first source/drain (S/D) feature adjoining active members of the first channel layers;
• and
• a second transistor over the first transistor, the second transistor including second channel layers and a second S/D feature adjoining active members of the second channel layers,
• wherein a number of the active members of the first channel layers is different from that of the active members of the second channel layers.

A method, comprising:

• receiving a workpiece including a substrate portion and a stack portion over the substrate portion, the stack portion including a first stack of first channel layers interleaved by first sacrificial layers and a second stack of second channel layers interleaved by second sacrificial layers, the second stack being above the first stack;
• forming a fin-shaped structure from the stack portion and the substrate portion, the fin-shaped structure including a source region and a drain region;
• forming a first source feature in the source region and a first drain feature in the drain region;
• depositing an isolation layer over the first source feature and the first drain feature, the isolation layer adjoining at least a bottommost one of the second channel layers;
• and
• forming a second source feature in the source region and over the isolation layer and a second drain feature in the drain region and over the isolation layer.