Method of manufacturing a semiconductor device and a semiconductor device

A semiconductor device, comprising:

• semiconductor wires disposed over a substrate;
• a source/drain epitaxial layer in contact with the semiconductor wires;
• a gate dielectric layer disposed on and wrapping around each channel region of the semiconductor wires;
• a gate electrode layer disposed on the gate dielectric layer and wrapping around each channel region;
• a gate sidewall spacer disposed on a side face of the gate electrode layer;
• and
• insulating spacers each enclosed by adjacent semiconductor wires, the gate dielectric layer and the source/drain epitaxial layer, wherein:
• each of the insulating spacers includes two layers having a first layer and a second layer formed on the first layer, and
• the first layer includes silicon germanium oxide.

A semiconductor device, comprising:

• semiconductor wires disposed over a bottom fin structure disposed over a substrate;
• a source/drain epitaxial layer in contact with the semiconductor wires;
• a gate dielectric layer disposed on and wrapping around each channel region of the semiconductor wires;
• a gate electrode layer disposed on the gate dielectric layer and wrapping around each channel region;
• a gate sidewall spacer disposed on a side face of the gate electrode layer;
• and
• insulating spacers each enclosed by adjacent semiconductor wires, the gate dielectric layer and the source/drain epitaxial layer,
• wherein each of the insulating spacers includes a layer made of germanium oxide.