Three-dimensional memory device with high mobility channels and nickel aluminum silicide or germanide drain contacts and method of making the same
A memory device can include a strained single-crystalline silicon layer and an alternating stack of insulating layers and electrically conductive layers located over the strained single-crystalline silicon layer. A memory opening fill structure extending through the alternating stack may include an epitaxial silicon-containing pedestal channel portion, and a vertical semiconductor channel, and a vertical stack of memory elements located adjacent to the vertical semiconductor channel Additionally or alternatively, a drain region can include a semiconductor drain portion and a nickel-aluminum-semiconductor alloy drain portion.
1. A memory device comprising:
an alternating stack of insulating layers and electrically conductive layers located over a semiconductor material layer;
a memory opening vertically extending through the alternating stack; and
a memory opening fill structure located in the memory opening and comprising a vertical semiconductor channel, a vertical stack of memory elements located adjacent to the vertical semiconductor channel at levels of the electrically conductive layers, and a drain region,
wherein the drain region comprises a semiconductor drain portion including a doped silicon-containing semiconductor material and contacting an end portion of the vertical semiconductor channel, and a nickel-aluminum-semiconductor alloy drain portion comprising silicon; and
wherein the memory opening fill structure comprises a dielectric core in contact with an inner sidewall of the vertical semiconductor channel and in contact with a bottom surface of the drain region.
2. The memory device of claim 1 , wherein:
a memory film vertically extends through a subset of the electrically conductive layers of the alternating stack; and
the vertical stack of memory elements comprises portions of the memory film that are located at levels of the subset of the electrically conductive layers.
3. The memory device of claim 2 , wherein:
the semiconductor drain portion contacts a first cylindrical sidewall segment of the memory film; and
the nickel-aluminum-semiconductor alloy drain portion contacts a second cylindrical sidewall segment of the memory film.
4. The memory device of claim 2 , further comprising a metallic drain electrode comprising an elemental metal or a conductive metallic nitride material in contact with a top surface of the nickel-aluminum-semiconductor alloy drain portion and a cylindrical sidewall segment of the memory film.
5. The memory device of claim 4 , further comprising forming an insulating cap layer overlying the alternating stack, wherein a top surface of the memory opening fill structure comprises a top surface of the metallic drain electrode, and is located within a horizontal plane including a top surface of the insulating cap layer.
6. The memory device of claim 4 , wherein the metallic drain electrode consists essentially of a material selected from W, Mo, Ta, Nb, TaN, TiN, and WN.
7. The memory device of claim 4 , wherein the metallic drain electrode consists essentially of W.
8. The memory device of claim 1 , wherein:
the semiconductor drain portion comprises a doped polysilicon including at least one electrical dopant species; and
the nickel-aluminum-semiconductor alloy drain portion comprises a nickel aluminum silicide, and the at least one electrical dopant species.
9. The memory device of claim 8 , wherein:
the vertical semiconductor channel comprises polysilicon having a doping of a first conductivity type; and
the semiconductor drain portion has a doping of a second conductivity type that is the opposite of the first conductivity type.
10. The memory device of claim 1 , wherein:
the semiconductor drain portion comprises a doped silicon-germanium compound semiconductor including at least one electrical dopant species; and
the nickel-aluminum-semiconductor alloy drain portion comprises a nickel aluminum silicide, a nickel aluminum germanide or a nickel aluminum silicide germanide, and the at least one electrical dopant species.
11. The memory device of claim 10 , wherein:
the vertical semiconductor channel comprises a doped polycrystalline silicon-germanium compound semiconductor material having a doping of a first conductivity type; and
the semiconductor drain portion has a doping of a second conductivity type that is the opposite of the first conductivity type.
12. A memory device comprising:
an alternating stack of insulating layers and electrically conductive layers located over a semiconductor material layer;
a memory opening vertically extending through the alternating stack; and
a memory opening fill structure located in the memory opening and comprising a vertical semiconductor channel, a vertical stack of memory elements located adjacent to the vertical semiconductor channel at levels of the electrically conductive layers, and a drain region,
wherein:
the drain region comprises a semiconductor drain portion including a doped silicon-containing semiconductor material and contacting an end portion of the vertical semiconductor channel, and a nickel-aluminum-semiconductor alloy drain portion comprising silicon;
a memory film vertically extends through a subset of the electrically conductive layers of the alternating stack;
the vertical stack of memory elements comprises portions of the memory film that are located at levels of the subset of the electrically conductive layers;
the semiconductor drain portion contacts a first cylindrical sidewall segment of the memory film; and
the nickel-aluminum-semiconductor alloy drain portion contacts a second cylindrical sidewall segment of the memory film.
13. The memory device of claim 12 , further comprising forming an insulating cap layer overlying the alternating stack, wherein a top surface of the memory opening fill structure comprises a top surface of the metallic drain electrode, and is located within a horizontal plane including a top surface of the insulating cap layer.
14. The memory device of claim 12 , wherein the metallic drain electrode consists essentially of a material selected from W, Mo, Ta, Nb, TaN, TiN, and WN.
15. The memory device of claim 12 , wherein the metallic drain electrode consists essentially of W.
16. A memory device comprising:
an alternating stack of insulating layers and electrically conductive layers located over a semiconductor material layer;
a memory opening vertically extending through the alternating stack; and
a memory opening fill structure located in the memory opening and comprising a vertical semiconductor channel, a vertical stack of memory elements located adjacent to the vertical semiconductor channel at levels of the electrically conductive layers, and a drain region,
wherein:
the drain region comprises a semiconductor drain portion including a doped silicon-containing semiconductor material and contacting an end portion of the vertical semiconductor channel, and a nickel-aluminum-semiconductor alloy drain portion comprising silicon;
a memory film vertically extends through a subset of the electrically conductive layers of the alternating stack; and
the vertical stack of memory elements comprises portions of the memory film that are located at levels of the subset of the electrically conductive layers; and
further comprising a metallic drain electrode comprising an elemental metal or a conductive metallic nitride material in contact with a top surface of the nickel-aluminum-semiconductor alloy drain portion and a cylindrical sidewall segment of the memory film.
17. A memory device comprising:
an alternating stack of insulating layers and electrically conductive layers located over a semiconductor material layer;
a memory opening vertically extending through the alternating stack; and
a memory opening fill structure located in the memory opening and comprising a vertical semiconductor channel, a vertical stack of memory elements located adjacent to the vertical semiconductor channel at levels of the electrically conductive layers, and a drain region,
wherein:
the drain region comprises a semiconductor drain portion including a doped silicon-containing semiconductor material and contacting an end portion of the vertical semiconductor channel, and a nickel-aluminum-semiconductor alloy drain portion comprising silicon;
the semiconductor drain portion comprises a doped silicon-germanium compound semiconductor including at least one electrical dopant species; and
the nickel-aluminum-semiconductor alloy drain portion comprises a nickel aluminum silicide, a nickel aluminum germanide or a nickel aluminum silicide germanide, and the at least one electrical dopant species.
18. The memory device of claim 17 , wherein:
the vertical semiconductor channel comprises a doped polycrystalline silicon-germanium compound semiconductor material having a doping of a first conductivity type; and
the semiconductor drain portion has a doping of a second conductivity type that is the opposite of the first conductivity type.