Method for manufacturing contact plugs for semiconductor devices

A method for manufacturing contact plugs for semiconductor devices, comprising:

• providing a substrate comprising a plurality of transistors and a first dielectric layer filling spaces between the transistors formed thereon, wherein the transistors respectively comprises a gate and a source/drain;
• forming a patterned sacrificial layer on the first dielectric layer, the patterned sacrificial layer comprising a plurality of first openings corresponding to the gates of the transistors;
• forming a second dielectric layer filling up the first openings;
• removing the patterned sacrificial layer to form a plurality of second openings in the second dielectric layer, the second openings being formed correspondingly to the sources/drains of the transistors;
• performing an etching process to etch the first dielectric layer through the second openings to form a plurality of first contact holes exposing the sources/drains of the transistors;
• forming a plurality of first contact plugs respectively in the first contact holes;
• forming a third dielectric layer on the transistors, the first contact plugs, and the first dielectric layer;
• etching the third dielectric layer to form a plurality of second contact holes in the third dielectric layer;
• forming a plurality of silicide layers on tops of the gates respectively after forming the second contact holes;
• and
• forming a plurality of second contact plugs respectively in the second contact holes.