Semiconductor device and method of forming same

A semiconductor device, comprising:

• a gate stack;
• a first dielectric material over the gate stack;
• a gate spacer on a sidewall of the gate stack and on a sidewall of the first dielectric material;
• an etch stop layer on a sidewall of the gate spacer opposite the gate stack;
• a source/drain contact adjacent the etch stop layer;
• a second dielectric material over the source/drain contact and over the etch stop layer, the second dielectric material physically contacting the sidewall of the gate spacer;
• a third dielectric material over the second dielectric material and over the gate spacer, the third dielectric material physically contacting a sidewall of the first dielectric material;
• a gate contact extending through the first dielectric material and physically contacting the gate stack and the gate spacer;
• and
• a source/drain contact plug extending through the second dielectric material and through the third dielectric material and physically contacting the source/drain contact and the sidewall of the gate spacer, the source/drain contact plug extending over the etch stop layer and over the gate spacer.

A method, comprising:

• forming a dummy gate structure over a fin, the fin protruding above a substrate;
• forming a gate spacer layer on sidewalls of the dummy gate structure;
• forming an etch stop layer on sidewalls of the gate spacer layer;
• replacing the dummy gate structure with a gate stack;
• forming a source/drain contact adjacent the etch stop layer;
• recessing the gate stack to form a first recess;
• filling the first recess with a first dielectric material having a first composition;
• recessing the source/drain contact and the etch stop layer to form a second recess;
• filling the second recess with a second dielectric material having a second composition;
• recessing the second dielectric material and the gate spacer layer to form a third recess;
• and
• filling the third recess with a third dielectric material having a third composition, wherein the third composition is different from the first composition and different from the second composition.