Methods of manufacturing a semiconductor device

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

• alternately and repeatedly forming a first insulation layer and a first sacrificial layer on a substrate to form a mold layer;
• forming a sacrificial layer structure on the mold layer, the sacrificial layer structure including a second sacrificial layer, an etch stop layer, a third sacrificial layer, a second insulation layer and a fourth sacrificial layer sequentially stacked;
• forming a hard mask on the sacrificial layer structure;
• etching the sacrificial layer structure and the mold layer by a dry etching process using the hard mask as an etching mask to form a channel hole exposing an upper surface of the substrate, and to form recesses on sidewalls of the second to fourth sacrificial layers;
• providing layers over the recesses in the channel hole to form a memory channel structure;
• and
• replacing the first sacrificial layer with a gate electrode.

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

• alternately and repeatedly forming a first insulation layer and a first sacrificial layer on a substrate to form a mold layer;
• forming a sacrificial layer structure on the mold layer, the sacrificial layer structure including an etch stop layer, a second sacrificial layer, and a second insulation layer sequentially stacked;
• forming a hard mask on the sacrificial layer structure;
• etching the sacrificial layer structure and the mold layer by a dry etching process using the hard mask as an etching mask to form a channel hole exposing an upper surface of the substrate and a recess on a sidewall of the sacrificial layer;
• providing layers over the recess in the channel hole to form a memory channel structure;
• and
• replacing the first sacrificial layer with a gate electrode, wherein
• an etch rate of the second sacrificial layer with respect to an etching gas in the dry etching process is greater than etch rates of the etch stop layer and the second insulation layer with respect to the etching gas such that a recess is formed on a sidewall of the second sacrificial layer adjacent to the channel hole during the dry etching process.