Semiconductor devices having field effect transistors
A semiconductor device having a field effect transistor and a method of fabricating the same. In-situ doped epitaxial patterns are respectively formed at both sidewalls of a protruded channel pattern from a substrate by performing an in-situ doped epitaxial growth process. The in-situ doped epitaxial pattern has a conformal impurity concentration throughout. Accordingly, source/drain regions with a conformal impurity concentration are connected throughout a channel width of a channel region including both sidewalls of a protruded channel pattern. As a result, it is possible to maximize a driving current of the filed effect transistor, and an on-off characteristic can be highly stabilized.
1. A semiconductor device comprising:
a channel pattern protruded from a substrate and having a pair of first sidewalls facing each other and a pair of second sidewalls facing each other;
a separated channel pattern vertically separated from the protruded channel pattern and having a pair of third sidewalls and a pair of fourth sidewalls, which are aligned with the first sidewalls and the second sidewalls, respectively;
a pair of in-situ doped epitaxial patterns respectively formed on the first sidewalls, the in-situ epitaxial pattern extended to be formed on the third sidewall;
a pair of conductive patterns, each of the pair respectively formed on each sidewall of the pair of the in-situ doped epitaxial patterns opposite the protruded and separated channel patterns;
a gate electrode crossing the protruded and separated channel patterns; and
a gate insulating layer interposed between the gate electrode and the protruded channel pattern, and between the gate electrode and the separated channel pattern.
2. The semiconductor device of claim 1 , wherein the separated channel pattern has a lattice width wider than that of the protruded channel pattern.
3. The semiconductor device of claim 1 , wherein the gate electrode fills in a tunnel surrounded by a bottom surface of the separated channel pattern, a top surface of the protruded channel pattern, and the in-situ doped epitaxial pattern, and
wherein the gate insulating layer is extended to be interposed between the in-situ doped epitaxial patterns and the gate electrode.
4. The semiconductor device of claim 1 , further comprising a channel interlayer pattern that fills in a tunnel surrounded by a bottom surface of the separated channel pattern, the top surface of the protruded channel pattern, and the in-situ doped epitaxial pattern, wherein the gate electrode crosses the protruded channel pattern, the channel interlayer pattern and the separated channel pattern, and
wherein the gate insulating layer is extended to be interposed between the gate electrode and the channel interlayer pattern.
5. The semiconductor device of claim 4 , wherein the separated channel pattern has a lattice width wider than that of the protruded channel pattern, and
wherein the channel interlayer pattern is made of a single crystalline semiconductor layer having a lattice width wider than that of the protruded channel pattern and having an etch selectivity with respect to the protruded channel pattern and the separated channel pattern.
6. The semiconductor device of claim 1 , wherein a plurality of separated channel patterns, each having respective third sidewalls, are stacked over the protruded channel pattern, and
wherein the plurality of separated channel patterns are vertically separated, and
wherein the in-situ doped epitaxial pattern is vertically extended to be in contact with the respective third sidewalls of the plurality of the separated channel patterns.
7. The semiconductor device of claim 6 , wherein the gate electrode fills in a first tunnel and at least a second tunnel, and
wherein the first tunnel is surrounded by a top surface of the protruded channel pattern, a bottom surface of a lowermost separated channel pattern among the plurality of separated channel patterns, and the in-situ doped epitaxial pattern, and
wherein the second tunnel is surrounded by top and bottom surfaces of neighboring isolated tunnel patterns and the in-situ doped epitaxial pattern, and
wherein the gate insulating layer is extended to be interposed between the in-situ doped epitaxial pattern.
8. The semiconductor device of claim 6 , further comprising:
a first channel interlayer pattern that fills in a first tunnel surrounded by a top surface of the protruded channel pattern, a bottom surface of a lowermost separated channel pattern among the plurality of separated channel patterns, and the in-situ doped epitaxial pattern; and
at least a second channel interlayer pattern that fills in at least a second tunnel surrounded by top and bottom surfaces of neighboring isolated tunnel patterns and the in-situ doped epitaxial pattern, wherein the gate electrode crosses the protruded channel pattern, first and second channel interlayer patterns, and the separated channel patterns, and
wherein the gate insulating layer is extended to be interposed between the gate electrode and the channel interlayer patterns.
9. The semiconductor device of claim 8 , wherein the separated channel patterns have a lattice width wider than the protruded channel pattern, and
wherein the channel interlayer patterns are made of a single crystalline semiconductor layer having a lattice width than that of the protruded channel pattern and having an etch selectivity with respect to the protruded channel pattern and the separated channel pattern, and
wherein the lattice width of the first channel interlayer pattern is gradually increased from a bottom surface of the first channel interlayer pattern to a top direction, and
wherein the second channel interlayer pattern has a conformal lattice width throughout the second channel interlayer pattern.
10. The semiconductor device of claim 1 , further comprising:
a device isolation layer placed on the substrate and surrounding the protruded channel pattern, the separated channel pattern, the in-situ doped channel pattern, and the conductive patterns; and
a mold layer covering the protruded channel pattern, the pair of in-situ doped epitaxial patterns, the pair of conductive patterns and the device isolation layer, wherein the gate electrode is placed within a first groove in the mold layer and a second groove in the device isolation layer, and
wherein the first groove crosses the protruded and separated channel patterns, and
wherein the second groove is aligned with the first groove and exposed upper portions of the fourth sidewalls of the separated channel pattern and the second sidewalls of the protruded channel pattern.
11. The semiconductor device of claim 10 , further comprising an insulating spacer interposed between inner walls of the first grove and the gate electrode, wherein the insulating spacer is formed on the inner walls of the first groove, and wherein the second groove is aligned with the insulating spacer.
12. The semiconductor device of claim 1 , further comprising a channel stop layer formed in the substrate beneath the protruded channel pattern.