Method of manufacturing semiconductor device to prevent defects

A method of manufacturing a semiconductor device, the method comprising:

• forming dummy gate structures including a dummy gate insulating layer and dummy gate electrodes, on a first region of a semiconductor substrate, the first region including a patterning region;
• forming spacers on two side walls of each of the dummy gate structures;
• forming an interlayer insulating layer on the semiconductor substrate and the dummy gate structures;
• forming a protective insulating layer on a second region of the semiconductor substrate, the second region being a non-patterning region;
• forming a liner layer on the protective insulating layer;
• planarizing the interlayer insulating layer;
• forming openings by removing the dummy gate structures;
• and
• forming gate structures including a gate insulating layer and metal gate electrodes, in the openings,
• wherein the interlayer insulating layer includes,
• a first interlayer insulating layer,
• a second interlayer insulating layer provided on the first interlayer insulating layer and formed of the same material as the spacers, and
• a third interlayer insulating layer provided on the second interlayer insulating layer, and
• wherein the protective insulating layer includes,
• a first protective insulating layer provided on the semiconductor substrate, and
• a second protective insulating layer provided on the first protective insulating layer,
• wherein the second interlayer insulating layer and the first protective insulating layer are simultaneously provided using substantially a same first material,
• the third interlayer insulating layer and the second protective insulating layer are simultaneously provided using substantially a same second material.