Abstract: Provided are methods for fabricating a semiconductor device. The methods include forming a hard mask pattern on a semiconductor substrate, forming a first trench having a first width and a second trench having a second width on the semiconductor substrate using the hard mask pattern as a mask, forming an oxide film on the hard mask pattern and the first and second trenches, forming first and second isolation films on the first and second trenches by planarizing the oxide film until the hard mask pattern is exposed, and etching the first isolation film by a first thickness by performing dry cleaning on the semiconductor substrate and etching the second isolation film by a second thickness different from the first thickness.

Abstract: According to a method of fabricating the semiconductor memory device, a contact plug can be protected while mold openings are formed. A semiconductor memory device may include a mold dielectric layer on an entire surface of a substrate, the substrate including a first region and a second region. A contact plug may be provided in a contact hole formed through the mold dielectric layer in the first region. A variable resistor may be provided in a mold opening formed through the mold dielectric layer in the second region. An upper surface of the contact plug may be at a level equal to or lower than an upper surface of the mold dielectric layer.

Abstract: A method of fabricating a semiconductor device can be provided by etching sidewalls of a preliminary trench in a substrate that are between immediately adjacent gate electrode structures, to recess the sidewalls further beneath the gate electrode structures to provide recessed sidewalls. Then, the recessed sidewalls and a bottom of the preliminary trench can be etched using crystallographic anisotropic etching to form a hexagonally shaped trench in the substrate.

Abstract: According to a method of fabricating the semiconductor memory device, a contact plug can be protected while mold openings are formed. A semiconductor memory device may include a mold dielectric layer on an entire surface of a substrate, the substrate including a first region and a second region. A contact plug may be provided in a contact hole formed through the mold dielectric layer in the first region. A variable resistor may be provided in a mold opening foamed through the mold dielectric layer in the second region. An upper surface of the contact plug may be at a level equal to or lower than an upper surface of the mold dielectric layer.

Abstract: A method of fabricating a semiconductor device can be provided by etching sidewalls of a preliminary trench in a substrate that are between immediately adjacent gate electrode structures, to recess the sidewalls further beneath the gate electrode structures to provide recessed sidewalls. Then, the recessed sidewalls and a bottom of the preliminary trench can be etched using crystallographic anisotropic etching to form a hexagonally shaped trench in the substrate.