Capacitor for semiconductor device
View Patent ↗A capacitor for a semiconductor device having a dielectric film between an upper electrode and a lower electrode is featured in that the dielectric film includes an alternately laminated film of hafnium oxide and titanium oxide at an atomic layer level.
1. A capacitor for a semiconductor device comprising an upper electrode, a lower electrode and a dielectric film therebetween, wherein the dielectric film comprises an alternately laminated film of hafnium oxide and titanium oxide at an atomic layer level.
2. The capacitor according to claim 1 , wherein the alternately laminated film of hafnium oxide and titanium oxide at an atomic layer level has a composition ratio of Hf/(Hf+Ti)=10 to 45 atomic %.
3. The capacitor according to claim 1 , wherein the alternately laminated film of hafnium oxide and titanium oxide at an atomic layer level is in an amorphous state.
4. The capacitor according to claim 1 , wherein the dielectric film further comprises aluminum oxide at a composition ratio of Al/(Al+Hf+Ti)=1 to 5 atomic %.
5. The capacitor according to claim 4 , wherein the aluminum oxide is formed in a layer shape in contact interfaces of the upper and lower electrodes with the dielectric film.
6. The capacitor according to claim 4 , wherein the aluminum oxide is formed between the layer of hafnium oxide and the layer of titanium oxide.
7. The capacitor according to claim 1 , wherein the dielectric film has a dielectric constant of 30 or more and a leakage current density of 1E-8 A/cm 2 or less at 1 V.
8. A semiconductor device including the capacitor according to claim 1 .
9. The semiconductor device according to claim 8 , wherein the semiconductor device is a DRAM.
10. A semiconductor device including the capacitor according to claim 2 .
11. The semiconductor device according to claim 10 , wherein the semiconductor device is a DRAM.
12. A semiconductor device including the capacitor according to claim 3 .
13. The semiconductor device according to claim 12 , wherein the semiconductor device is a DRAM.
14. A semiconductor device including the capacitor according to claim 4 .
15. The semiconductor device according to claim 14 , wherein the semiconductor device is a DRAM.
16. A semiconductor device including the capacitor according to claim 5 .
17. The semiconductor device according to claim 16 , wherein the semiconductor device is a DRAM.
18. A semiconductor device including the capacitor according to claim 6 .
19. The semiconductor device according to claim 18 , wherein the semiconductor device is a DRAM.
20. A semiconductor device including the capacitor according to claim 7 .
21. The semiconductor device according to claim 20 , wherein the semiconductor device is a DRAM.
22. A method for manufacturing a capacitor for a semiconductor device comprising:
(1) forming a lower electrode;
(2) alternately laminating hafnium oxide and titanium oxide at an atomic layer level on the lower electrode by an atomic layer deposition (ALD) method; and
(3) forming an upper electrode.
23. The method according to claim 22 , wherein the laminating step (2) by the ALD method includes:
a hafnium oxide layer forming cycle (A) which repeats, for a required number of times,
(A1) injecting an Hf precursor into a reaction chamber of an ALD apparatus, and forming a monolayer film of Hf compound on a substrate,
(A2) purging the inside of the reaction chamber of the ALD apparatus,
(A3) injecting an oxidizing gas into the reaction chamber of the ALD apparatus, and oxidizing the monolayer film of Hf compound, and
(A4) purging the inside of the reaction chamber of the ALD apparatus; and
a titanium oxide layer forming cycle (B) which repeats, for a required number of times,
(B1) injecting a Ti precursor into the reaction chamber of the ALD apparatus, and forming a monolayer film of Ti compound on the substrate,
(B2) purging the inside of the reaction chamber of the ALD apparatus,
(B3) injecting an oxidizing gas into the reaction chamber of the ALD apparatus, and oxidizing the monolayer film of Ti compound, and
(B4) purging the inside of the reaction chamber of the ALD apparatus, and
wherein a cycle (C) which is a combination of the cycle (A) and the cycle (B) is repeated for the number of times required for obtaining a dielectric film of a predetermined thickness.
24. The method according to claim 23 , wherein the number of times of the cycle (A) and the number of times of the cycle (B) are adjusted to satisfy Hf/(Hf+Ti)=10 to 45 atomic %.
25. The method according to claim 22 , further comprising the number of times of aluminum oxide layer forming cycles (D) which are required for satisfying Al/(Al+Hf+Ti)=1 to 5 atomic %, and each of which repeats, for a required number of times,
(D1) injecting an Al precursor into the reaction chamber of the ALD apparatus, and forming a monolayer film of Al compound on the substrate;
(D2) purging the inside of the reaction chamber of the ALD apparatus;
(D3) injecting an oxidizing gas into the reaction chamber of the ALD apparatus, and oxidizing the monolayer film of Al compound; and
(D4) purging the inside of the reaction chamber of the ALD apparatus.
26. The method according to claim 25 , wherein the cycle (D) is performed in contact interfaces of the upper and lower electrodes with a dielectric film.
27. The method according to claim 25 , wherein the cycle (D) is performed between the cycle (A) and the cycle (B).
28. The method according to claim 24 , further comprising high-speed heat treatment which is performed in a temperature range of 400 to 600° C. after the dielectric film is formed.
29. The method according to claim 25 , further comprising high-speed heat treatment which is performed in a temperature range of 400 to 700° C. after a dielectric film is formed.