Methods of fabricating semiconductor device

A method of fabricating a semiconductor device, comprising:

• forming a pattern on a substrate;
• and
• forming spacers on both sidewalls of the pattern,
• wherein the forming of the spacers comprises:
• forming a spacer layer on pattern;
• and
• injecting silicon ions into the spacer layer, and
• the injecting of the silicon ions is performed to form a first portion and a second portion in at least one of the spacers,
• wherein the first portion is positioned adjacent the pattern,
• wherein the second portion is spaced apart from the pattern with the first portion interposed therebetween, and
• wherein the second portion has a silicon concentration that is higher than a silicon concentration of the first portion.

A method of fabricating a semiconductor device, comprising:

• forming a gate pattern on a substrate;
• forming a spacer layer on sidewalls of the gate pattern that has a nitride-based low-k insulating layer that includes a dielectric constant that is lower than a dielectric constant of silicon oxide;
• injecting silicon ions into the spacer layer;
• forming an interlayer insulating layer on the gate pattern and the spacer layer;
• and
• forming contact holes that penetrate the interlayer insulating layer and expose sidewalls of the spacer layer.