Method of manufacturing semiconductor device

A method of manufacturing a semiconductor device comprising:

• forming a protection film above a semiconductor substrate;
• forming an impurity layer in the semiconductor substrate by ion implanting an impurity in the semiconductor substrate through the protection film;
• removing the protection film after forming the impurity layer;
• removing at least silicon that is component of a surface portion, that includes the impurity layer, of the semiconductor substrate after removing the protection film;
• epitaxially growing a semiconductor layer above the semiconductor substrate after removing at least silicon;
• forming a gate insulating film above the semiconductor layer;
• forming a gate electrode above the gate insulating film;
• and
• after forming the gate electrode, forming a source/drain region in the semiconductor layer,
• wherein the semiconductor device includes a transistor having a first region in the semiconductor layer below the gate insulating film with a first impurity concentration, and a second region in the semiconductor layer below the first region with a second impurity concentration which is higher than the first impurity concentration,
• wherein, oxygen is pushed into the semiconductor substrate by the ion implanting in the forming the impurity layer, and the oxygen, that is pushed into the semiconductor substrate, is removed in the removing at least silicon.