Method of forming field effect transistors

Claim 1

A method of forming field effect transistors comprising: forming a sacrificial masking layer over a semiconductor substrate; patterning the sacrificial masking layer effective to mask channel areas of the field effect transistors; forming lightly doped drain regions within source/drain areas of the semiconductor substrate using the masking layer to mask the channel areas; after forming the lightly doped drain regions, etching first trenches into the source/drain areas of the semiconductor substrate using the patterned sacrificial masking layer to mask the channel areas, the first trenches having semiconductive material comprising bases received elevationally lower than the lightly doped drain regions; forming insulative material within and overfilling the first trenches, the insulative material being received on the first trench bases; etching back the insulative material to leave lower portions of the first trenches filled with the insulative material while leaving outer portions of the first trenches open; forming semiconductive elevated source/drain material within the upper portions of the first trenches, the elevated source/drain material projecting elevationally outward of the first trenches; patterning a photoresist comprising masking layer to mask desired active area and expose desired trench isolation area, the photoresist comprising masking layer being formed over the sacrificial masking layer and the elevated source/drain material; using the patterned photoresist comprising masking layer, etching exposed portions of the sacrificial masking layer, the elevated source/drain material and semiconductive material of the substrate effective to form isolation trenches within said substrate semiconductive material of the substrate; overfilling the isolation trenches with isolation material, the isolation material including portions that project outwardly of the isolation trenches; etching a plurality of gate line trenches into at least those portions of the trench isolation material that project outwardly of the isolation trenches; after etching the plurality of gate line trenches, removing all remaining of the sacrificial masking layer from the substrate; and after the removing, forming conductive gate material within the gate line trenches and over the active area.

Claim 2

A method of forming field effect transistors comprising: forming a sacrificial masking layer over a semiconductor substrate; patterning the sacrificial masking layer effective to mask channel areas of the field effect transistors; forming lightly doped drain regions within source/drain areas of the semiconductor substrate using the masking layer to mask the channel areas; after forming the lightly doped drain regions, etching first trenches into the source/drain areas of the semiconductor substrate using the patterned sacrificial masking layer to mask the channel areas, the first trenches having semiconductive material comprising bases received elevationally lower than the lightly doped drain regions; forming insulative material within and overfilling the first trenches, the insulative material being received on the first trench bases; etching back the insulative material to leave lower portions of the first trenches filled with the insulative material while leaving outer portions of the first trenches open; forming semiconductive elevated source/drain material within the upper portions of the first trenches, the elevated source/drain material projecting elevationally outward of the first trenches; patterning a photoresist comprising masking layer to mask desired active area and expose desired trench isolation area, the photoresist comprising masking layer being formed over the sacrificial masking layer and the elevated source/drain material; using the patterned photoresist comprising masking layer, etching exposed portions of the sacrificial masking layer, the elevated source/drain material and semiconductive material of the substrate effective to form isolation trenches within said substrate semiconductive material of the substrate; overfilling the isolation trenches with isolation material, the isolation material including portions that project outwardly of the isolation trenches; etching a plurality of gate line trenches into at least those portions of the trench isolation material that project outwardly of the isolation trenches; after etching the plurality of gate line trenches, removing all remaining of the sacrificial masking layer from the substrate; and after the removing, forming conductive gate material within the gate line trenches and over the active area.