VIAS and Via Rails for Source/Drain Metal Full Contact

A method of forming a semiconductor device, comprising:

• receiving a workpiece having a first metal gate stack over a first channel region, a second metal gate stack over a second channel region, a source/drain (S/D) feature between the first and second channel regions, and an S/D contact over the S/D feature;
• forming first and second dielectric caps covering and in direct contact with the first and second metal gate stacks, respectively;
• forming a contact etch stop layer (CESL) over the S/D contact and over the first and second dielectric caps, wherein the CESL and the first and second dielectric caps are made of different materials;
• forming an interlayer dielectric (ILD) layer over the CESL;
• forming a gate via trench through the ILD layer, through the CESL, and through the first dielectric cap, the gate via trench exposes a top surface of the first metal gate stack;
• forming a gate via in the gate via trench;
• forming an S/D via trench through the ILD layer and through the CESL, the S/D via trench exposes a top surface of the S/D contact and a side and a top surface of the gate via;
• and
• forming an S/D via in the S/D via trench, wherein the S/D via lands on the top surface of the S/D contact and the side and top surfaces of the gate via.

A semiconductor device, comprising:

• metal gate stacks over channel regions of a substrate;
• gate spacers on sidewalls of the metal gate stacks;
• dielectric caps landing on and covering the metal gate stacks and the gate spacers;
• first etch stop layers on sidewalls of the gate spacers and the dielectric caps;
• source/drain (S/D) features between the channel regions of the substrate;
• S/D contacts between metal gate stacks and landing on the S/D features;
• a second etch stop layer over the dielectric caps, the first etch stop layers, and the S/D contacts;
• an interlayer dielectric (ILD) layer over the second etch stop layer;
• and
• a first S/D via penetrating through the ILD layer and the second etch stop layer to make direct contact with multiple S/D contacts and multiple dielectric caps by extending lengthwise along a first direction,
• wherein the second etch stop layer and the dielectric caps are made of different materials.