Method for fabricating a semiconductor device

A method for fabricating a semiconductor device, the method comprising:

• forming a mask pattern on a substrate;
• forming a fin protruding on the substrate by etching the substrate using the mask pattern;
• forming a pre-isolation layer covering the fin and the mask pattern;
• exposing the mask pattern by removing a portion of the pre-isolation layer by performing a first polishing process;
• and
• planarizing the pre-isolation layer such that an upper surface of the fin and an upper surface of the pre-isolation layer are coplanar by performing a second polishing process for exposing the mask pattern and then exposing the upper surface of the fin.

A method for fabricating a semiconductor device, the method comprising:

• forming a first mask pattern on a substrate;
• forming a mask layer substantially conformally along an upper surface of the substrate having the first mask pattern;
• patterning the mask layer to form a second mask pattern exposing the first mask pattern;
• removing the first mask pattern to expose the substrate on both sides of the mask pattern;
• forming a plurality of fins on a first region of the substrate but not on a second region of the substrate by etching the substrate using the second mask pattern;
• forming a pre-isolation layer covering the fins and the second mask pattern remaining on upper surfaces of the fins;
• exposing the second mask pattern by removing a portion an upper layer of the pre-isolation layer covering the fins by performing a first polishing process;
• performing a densification process to oxidize the upper layer of the pre-isolation layer after exposing the second mask pattern;
• removing a portion of the upper layer of the pre-isolation layer surrounding lateral surfaces of the second mask pattern;
• removing the second mask pattern after removing the portion of the upper layer of the pre-isolation layer, thereby exposing the upper surfaces of the fins;
• doping impurities into the fins after removing the second mask pattern;
• removing the remaining portion of the upper layer of the pre-isolation layer by performing a second polishing process, thereby planarizing the pre-isolation layer such that the upper surface of the fins are coplanar with an upper surface of the pre-isolation layer;
• and
• removing a portion of a lower layer of the pre-isolation layer to thereby form an isolation layer which contacts a lower portion of the fins and wherein the fins protrude from isolation layer.