Uniform silicide metal on epitaxially grown source and drain regions of three-dimensional transistors
View Patent ↗A method for fabricating a three-dimensional transistor is described. Atomic Layer Deposition of nickel, in one embodiment, is used to form a uniform silicide on all epitaxially grown source and drain regions, including those facing downwardly.
1. A method for fabricating a three-dimensional semiconductor device comprising:
growing an epitaxial layer on source and drain regions of a three-dimensional semiconductor body which includes a gate structure, where the growth results in facets facing at least partially downward; and
forming a silicide metal selectively on the epitaxial layer, such that the metal forms on the facets facing at least partially downward.
2. The method defined by claim 1 , wherein the suicide metal is formed using a controlled chemical vapor deposition (CVD).
3. The method defined by claim 1 , wherein the silicide is formed with a relatively uniform thickness including on the facets facing at least partially downward.
4. The method defined by claim 3 , wherein the silicide metal is formed using atomic layer deposition (ALD).
5. The method defined by claim 4 , wherein the body comprises silicon.
6. The method defined by claim 5 , wherein the epitaxial growth comprises growing silicon.
7. The method defined by claim 6 , wherein the forming of the silicide method includes depositing nickel.
8. The method defined by claim 7 , wherein the deposition of the nickel includes use of a homoleptic nitrogen.
9. The method defined by claim 8 , wherein the ALD process employs hydrogen.
10. The method defined by claim 9 , wherein the ALD process employs homoleptic N,N′-dialkylacetamidinato nickel.
11. A method for fabricating a three-dimensional semiconductor device comprising:
forming a silicon body;
forming a gate structure covering at least three sides of the body;
growing an epitaxial layer on the body adjacent the gate structure, the epitaxial layer having overhung regions with facets with downwardly facing surfaces; and
selectively forming a substantially uniform silicide metal on the epitaxial layer including on the downwardly facing surfaces.
12. The method defined by claim 11 , wherein the forming of the silicide metal uses atomic layer deposition (ALD).
13. The method defined by claim 12 , wherein the ALD process includes the deposition of nickel.
14. The method defined by claim 13 , wherein the formation of the nickel silicide includes the use of a homoleptic nitrogen nickel precursor.
15. The method defined by claim 14 , including the use of hydrogen with the nickel precursor.
16. The method defined by claim 15 , including the use of homoleptic N,N′dialkylacetamidinato nickel.