Semiconductor Device and Method

A semiconductor device comprising:

• a nanostructure over a substrate;
• a source/drain region adjacent the nanostructure;
• a gate electrode surrounding the nanostructure in a cross-sectional view;
• and
• an inner spacer under the nanostructure, the inner spacer between the source/drain region and the gate electrode, the inner spacer comprising SiOCN, the inner spacer comprising a gradient of atomic percentage of oxygen from 35% to 30% measured from a surface of the inner spacer contacting the source/drain region into the inner spacer.

A semiconductor device comprising:

• a first nanostructure over a substrate;
• a second nanostructure over the first nanostructure;
• a gate electrode around the first nanostructure and the second nanostructure;
• a gate dielectric layer between the gate electrode and the first nanostructure and between the gate electrode and the second nanostructure;
• a source/drain region adjacent the first nanostructure and the second nanostructure;
• and
• a first inner spacer between the gate electrode and the source/drain region, the first inner spacer being below the first nanostructure, the first inner spacer having a gradient of atomic percentage of oxygen from 30% to 60% measured from a first sidewall of the first inner spacer contacting the source/drain region into the first inner spacer.