Semiconductor device and method for manufacturing the same

A semiconductor device, comprising:

• a first channel;
• a second channel;
• a first dielectric sheath layer around the first channel;
• a second dielectric sheath layer around the second channel, wherein the first dielectric sheath layer and the second dielectric sheath layer comprise different materials;
• and
• a metal gate electrode continuously extending across the first dielectric sheath layer and the second dielectric sheath layer.

A method, comprising:

• forming a first nanowire and a second nanowire over a semiconductor substrate;
• depositing a first dielectric sheath layer over the first nanowire and the second nanowire;
• removing a first portion of the first dielectric sheath layer from the second nanowire, wherein a second portion of the first dielectric sheath layer remains over the first nanowire;
• depositing a second dielectric sheath layer over the second nanowire, wherein the first dielectric sheath layer and the second dielectric sheath layer comprise different materials;
• and
• depositing a metal layer over the first dielectric sheath layer and the second dielectric sheath layer.