Electron blocking layers for electronic devices
Methods and apparatuses for electronic devices such as non-volatile memory devices are described. The memory devices include a multi-layer control dielectric, such as a double or triple layer. The multi-layer control dielectric includes a combination of high-k dielectric materials such as aluminum oxide, hafnium oxide, and/or hybrid films of hafnium aluminum oxide. The multi-layer control dielectric provides enhanced characteristics, including increased charge retention, enhanced memory program/erase window, improved reliability and stability, with feasibility for single or multi state (e.g., two, three or four bit) operation.
1. A gate stack of a memory device, the gate stack comprising the following layers, with each successive layer above the preceding underlying layers:
a first dielectric layer, wherein the first dielectric layer is a tunneling dielectric layer;
a charge storage layer on and above the first dielectric layer;
a second dielectric layer comprising a high-k dielectric material directly on and above the charge storage layer;
a third dielectric layer comprising SiO 2 on and above the second dielectric layer;
a fourth dielectric layer comprising Si 3 N 4 on and above the third dielectric layer;
a fifth dielectric layer comprising SiO 2 on and above the fourth dielectric layer, and
a sixth dielectric layer comprising a high-k dielectric material on and above the fifth dielectric layer.
2. The gate stack of claim 1 , wherein the charge storage layer comprises nanocrystals.
3. The gate stack of claim 2 , wherein the nanocrystals comprise ruthenium nanocrystals.
4. The gate stack of claim 1 , wherein the charge storage layer comprises a continuous floating gate.
5. The gate stack of claim 1 , wherein each of the third, fourth, and fifth dielectric layers has a thickness of 3 nm or less.
6. The gate stack of claim 1 , wherein each of the second and the sixth dielectric layers has a thickness of 4 nm or less.
7. The gate stack of claim 6 , wherein each of the second and the sixth dielectric layers has a thickness of 2 nm or less.
8. The gate stack of claim 1 , wherein each of the second and the sixth dielectric layers comprises one of hafnium and zirconium.
9. The gate stack of claim 8 , wherein at least one of the second and the sixth dielectric layers comprises one of HfO 2 and ZrO.
10. The gate stack of claim 1 , wherein at least one of the second and the sixth dielectric layers comprises a metal silicate.
11. The gate stack of claim 10 , wherein the metal silicate is selected from the group consisting of a hafnium silicate and an aluminum silicate.
12. The gate stack of claim 1 , further comprising a seventh dielectric layer of 1 nm or less in thickness disposed between at least one of: (a) the second dielectric layer and the third dielectric layer; and (b) the fifth dielectric layer and the sixth dielectric layer.
13. The gate stack of claim 12 , wherein the seventh dielectric layer comprises aluminum oxide.
14. The gate stack of claim 1 , wherein the memory device exhibits a charge loss of no more than about 0.1 V over a period of 60 minutes at a temperature of 250° C.
15. A gate stack of a memory device, the gate stack comprising the following layers, with each successive layer above the preceding underlying layers:
a first dielectric layer, wherein the first dielectric layer is a tunneling dielectric layer;
a charge storage layer comprising localized charge traps on and above the first dielectric layer, wherein the charge storage layer comprises nanocrystals;
a second dielectric layer comprising SiO 2 on and above the charge storage layer;
a third dielectric layer comprising Si 3 N 4 on and above the second dielectric layer;
a fourth dielectric layer comprising SiO 2 on and above the third dielectric layer; and
a fifth dielectric layer comprising a high-k dielectric material directly on and above the fourth dielectric layer.
16. The gate stack of claim 15 , wherein the charge storage layer comprises a nitride layer.
17. The gate stack of claim 15 , further comprising a sixth dielectric layer disposed between the charge storage layer and the second dielectric layer, the sixth dielectric layer comprising a high-k dielectric material.
18. The gate stack of claim 17 , wherein the sixth dielectric layer comprises one of HfO 2 and ZrO 2 .
19. The gate stack of claim 17 , wherein the sixth dielectric layer comprises a metal silicate selected from the group consisting of a hafnium silicate and an aluminum silicate.
20. The gate stack of claim 15 , wherein the fifth dielectric layer comprises one of HfO 2 and ZrO 2 .
21. The gate stack of claim 15 , wherein the fifth dielectric layer comprises a metal silicate selected from the group consisting of a hafnium silicate and an aluminum silicate.
22. A gate stack of a memory device, the gate stack comprising the following layers, with each successive layer above the preceding underlying layers:
a first dielectric layer, wherein the first dielectric layer is a tunneling dielectric layer;
a charge storage layer comprising localized charge traps on and above the first dielectric layer;
a second dielectric layer comprising SiO 2 on and above the charge storage layer;
a third dielectric layer comprising Si 3 N 4 on and above the second dielectric layer;
a fourth dielectric layer comprising SiO 2 on and above the third dielectric layer;
a fifth dielectric layer of 1 nm or less in thickness disposed on and above the fourth dielectric layer; and
a sixth dielectric layer comprising a high-k dielectric material disposed on and above the fifth dielectric layer.
23. The gate stack of claim 22 , wherein the sixth dielectric layer is Al 2 O 3 .
24. A gate stack of a memory device, the gate stack comprising the following layers, with each successive layer above the preceding underlying layers:
a tunneling dielectric layer;
a charge storage layer comprising nanocrystals on and above the tunneling dielectric layer;
a first charge blocking layer on and above the charge storage layer, the first charge blocking layer comprising hafnium, wherein the first charge blocking layer is in direct physical contact with the charge storage layer;
a control dielectric layer including a first oxide layer on and above the first charge blocking layer;
a nitride layer on and above the first oxide layer;
a second oxide layer on and above the nitride layer; and
a second charge blocking layer on and above the control dielectric layer, the second charge blocking layer comprising hafnium.
25. The gate stack of claim 24 ,
wherein the tunneling dielectric layer comprises SiO 2 ,
wherein the nanocrystals comprise Ru,
wherein the first charge blocking layer comprises HfO 2 ,
wherein the first oxide layer comprises SiO 2 ,
wherein the nitride layer comprises Si 3 N 4 ,
wherein the second oxide layer comprises SiO 2 , and
wherein the second charge blocking layer comprises HfO 2 .