Impact ionization semiconductor device and manufacturing method thereof
A semiconductor device including a field effect transistor (FET) device includes a substrate and a channel structure formed of a two-dimensional ( 2 D) material over the substrate. Source and drain contacts are formed partially over the 2 D material. A first dielectric layer is formed at least partially over the channel structure and at least partially over the source and drain contacts. The first dielectric layer is configured to trap charge carriers. A second dielectric layer is formed over the first dielectric layer, and a gate electrode is formed over the second dielectric layer.
1. A method for manufacturing a semiconductor device, comprising:
disposing a gate electrode layer over a substrate;
disposing a dielectric layer over the gate electrode layer;
disposing and patterning a photo-resist layer over the dielectric layer to cover at least a middle portion of the dielectric layer;
forming a charge-trapping layer inside a portion of the dielectric layer not covered by the photo-resist layer;
disposing a two-dimensional (2D) material layer over the charge-trapping layer and a remaining portion of the dielectric layer after removing the patterned photo-resist layer; and
forming source and drain contacts over the 2D material layer,
wherein the charge-trapping layer comprises a first portion extending under the source contact in the dielectric layer that does not extend from under the source contact to under the drain contact and does not extend under the drain contact.
2. The method of claim 1 , further comprising:
disposing one or more spacer layers between the dielectric layer and the gate electrode layer, wherein the semiconductor device is a bottom gate device.
3. The method of claim 1 , further comprising:
extending a section of the charge-trapping layer under the source contact beyond a source contact limit into the dielectric layer.
4. The method of claim 1 , further comprising:
forming an interfacial layer between the charge-trapping layer and the 2D material layer, wherein the interfacial layer comprises a 2D insulator material including alumina (Al 2 O 3 ) or hexagonal boron nitride.
5. The method of claim 1 , wherein forming the charge-trapping layer comprises:
performing plasma treatment of the dielectric layer of the portion of the dielectric layer not covered by the photo-resist layer to form the charge-trapping layer.
6. The method of claim 5 , wherein the performing the plasma treatment further comprises:
performing the plasma treatment of the dielectric layer using nitrogen or ammonia to form the charge-trapping layer.
7. The method of claim 1 , wherein the disposing the 2D material layer further comprises:
disposing the 2D material layer using a semiconducting 2D material including a transition metal dichalcogenide (TMDC), wherein the TMDC includes an element from a list of elements including molybdenum (Mo), tungsten (W), titanium (Ti), tantalum (Ta), niobium (Nb), hafnium (Hf), zirconium (Zr), and palladium (Pd) or comprises molybdenum disulfide (MoS 2 ) or tungsten selenide (WSe 2 ).
8. The method of claim 1 , wherein the disposing the dielectric layer over the gate electrode layer comprises forming a charge-trapping dielectric layer including an oxide or a nitride dielectric over the gate electrode layer.
9. The method of claim 8 , wherein the disposing the dielectric layer over the gate electrode layer further comprises:
forming the charge-trapping dielectric layer with the oxide or the nitride dielectric that includes at least one element from a group consisting of tantalum (Ta), titanium (Ti), hafnium (Hf), zirconium (Zr), aluminum (Al), lanthanum (La), yttrium (Y), niobium (Nb), silicon (Si), germanium (Ge), and gallium (Ga).
10. The method of claim 1 , wherein the forming the charge-trapping layer further comprises:
forming the charge-trapping layer with a thickness that is within a range of about 1-10 nm, and wherein trapped charge carriers include holes.
11. The method of claim 1 , wherein the forming source and drain contacts further comprises:
forming Schottky contacts for the source and drain contacts.
12. The method of claim 1 , wherein source and drain contact materials include at least one element from a group consisting of Mo, W, Ti, Al, Ta, Sr, Pd, gold (Au), silver (Ag), copper (Cu), Hf, Zr, and Nb.
13. A method for manufacturing a semiconductor device, comprising:
disposing a gate electrode layer over a substrate;
disposing a dielectric layer over the gate electrode layer;
forming a charge-trapping layer in the dielectric layer;
disposing a two-dimensional (2D) material layer over the charge-trapping layer; and
forming source and drain contacts over the 2D material layer, wherein:
the semiconductor device is a bottom gate device, and
the charge-trapping layer comprises a portion extending under the source contact that does not extend in the dielectric layer between under the source contact and under the drain contact and does not extend under the drain contact.
14. The method of claim 13 , wherein the forming source and drain contacts further comprises:
forming Schottky contacts for the source and drain contacts.
15. A method for manufacturing a semiconductor device, comprising:
disposing a gate electrode layer over a substrate;
disposing a dielectric layer over the gate electrode layer;
forming a charge-trapping layer in the dielectric layer to trap charge carriers, the charge-trapping layer comprising a first portion under a source contact and a second portion separated from the first portion and under a drain contact, wherein the charge-trapping layer comprises a charge-trapping dielectric layer including an oxide or nitride dielectric;
disposing a two-dimensional (2D) material layer over the charge-trapping layer to form a channel structure; and
forming the source and drain contacts over the channel structure,
wherein forming the charge-trapping layer comprises:
treating the dielectric layer to form the charge-trapping layer on top of the dielectric layer and in contact with the channel structure, and
the charge-trapping layer comprises a portion in the dielectric layer under the source contact and under the drain contact that does not extend from under the source contact to under the drain contact.
16. The method of claim 15 , further comprising:
extending a section of the charge-trapping layer under the source contact beyond a source contact limit into the dielectric layer.
17. The method of claim 15 , wherein the forming the source and drain contacts further comprises:
forming Schottky contacts for the source and drain contacts.
18. The method of claim 15 , wherein the treating the dielectric layer further comprises:
performing a plasma treatment of the dielectric layer using nitrogen or ammonia to form the charge-trapping layer.
19. The method of claim 15 , wherein the forming the charge-trapping layer further comprises:
forming the charge-trapping layer with a thickness that is within a range of about 1-10 nm, and wherein trapped charge carriers include holes.
20. The method of claim 15 , wherein the disposing the dielectric layer over the gate electrode layer comprises forming a charge-trapping dielectric layer including an oxide or a nitride dielectric over the gate electrode layer).