Adjusting method of channel stress

An adjusting method of channel stress, comprising:

• providing a substrate;
• forming a metal-oxide-semiconductor field-effect transistor on the substrate, the metal-oxide-semiconductor field-effect transistor comprising a source/drain region, a channel, a dummy gate, a gate dielectric layer and a spacer;
• forming a dielectric layer on the substrate and covering the metal-oxide-semiconductor field-effect transistor;
• applying a flattening process onto the dielectric layer to expose the dummy gate of the metal-oxide-semiconductor field-effect transistor;
• removing the dummy gate;
• filling a metal to substitute for the dummy gate;
• removing the remaining dielectric layer to expose the source/drain region;
• and
• forming a non-conformal high stress dielectric layer on the substrate having the exposed source/drain region to cover the metal-oxide-semiconductor field-effect transistor, the non-conformal high stress dielectric layer being made of a single material.