Transistors having ultra thin fin profiles and their methods of fabrication

A method of forming an integrated circuit comprising:

• forming a trench in an insulation layer disposed on a semiconductor substrate, the trench having an aspect ratio of at least 2:1 at the largest width of the trench;
• forming a III-V semiconductor material in the trench and above a top surface of the insulation layer;
• planarizing the III-V semiconductor material that extends over the trench to a level generally coplanar with the top surface of the insulation layer;
• recessing the III-V semiconductor material in the trench so that the III-V semiconductor material has a top surface lower than the top surface of the insulation layer;
• forming a group IV semiconductor material on the III-V semiconductor material in the trench and extending above the top surface of the insulation layer;
• planarizing the portion of a group IV semiconductor material that extends over the trench to a level generally coplanar with the top surface of the insulation layer;
• recessing the insulation layer so that the group IV semiconductor has a top and sidewalls extending above the recessed top surface of the insulation layer to form an active fin portion;
• and
• thinning the sidewalls of the active fin portion to create a thinned active fin portion.

A device comprising:

• a semiconductor substrate:
• an insulation layer disposed on the semiconductor substrate, the insulation layer having a top surface;
• a trench disposed in the insulation layer;
• a fin having an active fin portion disposed on a subfin portion, the subfin portion having a lower portion formed in a faceted notch in the substrate below the insulation layer and an upper portion disposed in the trench in the insulation layer wherein the width the upper portion of the subfin portion at the bottom of the trench is wider than the width of the upper portion of the subfin at the top of the insulation layer, wherein the subfin portion comprises a III-V semiconductor material and wherein the active fin portion comprises a semiconductor material different from the III-V semiconductor material of the subfin portion, and wherein the active fin portion has a top active fin portion and a bottom active fin portion, and the top of the active fin portion has a smaller width than the bottom active fin portion, and wherein the bottom active fin portion is above the top surface of the insulation layer.

An integrated circuit comprising:

• a semiconductor substrate;
• an insulation layer formed on the semiconductor substrate;
• a fin extending from the semiconductor substrate, the fin having a subfin portion on the semiconductor substrate and an active fin portion on the subfin portion, the subfin portion disposed in a trench formed in the insulation layer, the subfin portion comprising a III-V semiconductor material and the active fin portion comprising a group IV semiconductor material;
• and
• a second fin extending from the semiconductor substrate, the second fin having a second subfin portion on the semiconductor substrate and a second active fin portion on the second subfin portion, the second subfin portion disposed in a second trench disposed in the insulation layer, the second trench having an aspect ratio (depth to width) of at least 2:1, the second subfin portion comprising the III-V semiconductor material, the second active fin portion comprising a second III-V semiconductor material different than the III-V semiconductor material.

An integrated circuit comprising:

• a semiconductor substrate;
• an insulation layer formed on the semiconductor substrate;
• and
• a fin extending from the semiconductor substrate, the fin having a subfin portion on the semiconductor substrate and an active fin portion on the subfin portion, the subfin portion disposed in a trench formed in the insulation layer, the subfin portion comprising a III-V semiconductor material and the active fin portion comprising a group IV semiconductor material, wherein the active fin portion has a top active fin portion and a bottom active fin portion, and the top of the active fin portion has a smaller width than the bottom active fin portion, wherein the active fin portion has a top and sidewalls extending above the insulation layer, and wherein the subfin portion has a top subfin portion and a bottom subfin portion in the trench in the insulation layer wherein the bottom active fin portion is disposed directly on the top of a subfin portion and wherein the bottom active fin portion has a smaller width than the top subfin portion.