Forming a sacrificial liner for dual channel devices

A method comprising:

• providing a substrate having thereon a layer of epitaxial channel material;
• patterning a hardmask above the layer of epitaxial channel material;
• performing a first etch, using the hardmask as a mask, to form an upper portion of a first fin and an upper portion of a second fin, the first fin adjacent to the second fin, the first etch extending beyond a bottom surface of the layer of epitaxial channel material;
• forming a liner over exposed surfaces of the upper portions of the first and second fins;
• performing a second etch, using the liner as a mask, to form a lower portion of the first fin and a lower portion of the second fin;
• subsequent to performing the second etch, filling gaps between the first fin and the second fin with a dielectric material;
• recessing the dielectric material to a level below the upper surfaces of the first and second fins;
• and
• removing the liner,
• subsequent to removing the liner, forming a gate dielectric on exposed surfaces of the upper portions of the first and second fins, wherein the gate dielectric extends beyond the bottom surface of the layer of epitaxial channel material.

A method comprising:

• providing a substrate having thereon a first region comprising a layer of first epitaxial channel material and a second region comprising a layer of second epitaxial channel material;
• patterning a hardmask above the first and second regions;
• performing a first etch, using the hardmask as a mask, to form an upper portion of a first fin comprising the layer of first epitaxial channel material and an upper portion of a second fin comprising the layer of second epitaxial channel material;
• forming a liner over exposed surfaces of the upper portions of the first and second fins;
• performing a second etch, using the liner as a mask, to form a lower portion of the first fin and a lower portion of the second fin;
• subsequent to performing the second etch, filling a gap between the first and second fins with a dielectric material;
• recessing the dielectric material to a level below the upper surfaces of the first and second fins;
• and
• removing the liner,
• subsequent to removing the liner, forming a gate dielectric on exposed surfaces of the upper portions of the first and second fins, wherein the gate dielectric extends beyond bottom surfaces of the layers of first and second epitaxial channel materials.