Semiconductor device with contact plug

A semiconductor device, comprising:

• a substrate with a first portion and two second portions sandwiching the first portion;
• an epi-layer disposed in the first portion;
• a silicide cap disposed on the epi-layer;
• a contact plug disposed on the silicide cap;
• a first etch stop layer disposed on the second portions and extending to the first portion;
• an interlayer dielectric (ILD) layer disposed on the first etch stop layer and extending to the first portion;
• a second etch stop layer disposed on the ILD layer and extending to the first portion, wherein the first etch stop layer, the ILD layer and the second etch stop layer form a sidewall;
• a protective layer peripherally enclosed by the sidewall, wherein the protective layer is formed from oxide or nitride;
• and
• a liner peripherally enclosed by the protective layer that enhances an adhesive effect between the sidewall and the liner, wherein the protective layer and the liner are formed from different materials.

A semiconductor device, comprising:

• a substrate with two first portions and one second portion sandwiched by the first portions;
• an epi-layer disposed in each of the first portions;
• a silicide cap disposed on the epi-layer;
• a contact plug disposed on the silicide cap;
• a first etch stop layer disposed on the second portion and extending to the first portions;
• an interlayer dielectric (ILD) layer disposed on the first etch stop layer and extending to the first portions;
• a second etch stop layer disposed on the ILD layer and extending to the first portions, wherein the first etch stop layer, the ILD layer and the second etch stop layer form a sidewall on each of the first portions of the substrate;
• a protective layer peripherally enclosed by the sidewall, wherein the protective layer is formed from oxide or nitride;
• and
• a liner peripherally enclosed by the protective layer that enhances an adhesive effect between the sidewall and the liner, wherein the protective layer and the liner are formed from different materials.