Processes for making a barrier between a dielectric and a conductor and products produced therefrom

• US 6,677,254 B2
• Filed: 07/23/2001
• Issued: 01/13/2004
• Est. Priority Date: 07/23/2001
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Rajagopalan, Ravi, Sinensky, Asher, Athreya, Shankarram, Narwankar, Pravin, Urdahl, Randall S., Bakli, Mouloud
• Primary Examiner(s): Zarabian, Amir
• Assistant Examiner(s): VOCKRODT, JEFF B
• Application Number:
  US09/911,947
• Publication Number:
  US 20030025146A1
• Time in Patent Office: 904 Days
• Field of Search: 438/240, 438/785, 438/786, 438/769, 438/770, 438/775
• US Class Current: 438/785
• CPC Class Codes: H01L 21/02183 the material containing tantalum, e.g. Ta2O5
• CPC Class Codes: H01L 21/022 the layer being a laminate, i.e. composed of sublayers, e.g. stacks of alternating high-k metal oxides adhesion layers or buffer layers H01L21/02304, H01L21/02362
• CPC Class Codes: H01L 21/02244 of a metallic layer
• CPC Class Codes: H01L 21/02252 formation by plasma treatment, e.g. plasma oxidation of the substrate after treatment of an insulating film by plasma H01L21/3105 and subgroups
• CPC Class Codes: H01L 21/02271 deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition H01L21/02266 takes precedence
• CPC Class Codes: H01L 21/02323 introduction of oxygen
• CPC Class Codes: H01L 21/02332 into an oxide layer, e.g. changing SiO to SiON
• CPC Class Codes: H01L 21/0234 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/3143 composed of alternated layers or of mixtures of nitrides and oxides or of oxinitrides, e.g. formation of oxinitride by oxidation of nitride layers
• CPC Class Codes: H01L 21/31604 Deposition from a gas or vapour H01L21/31691, H01L21/31695 take precedence
• CPC Class Codes: H01L 28/40 Capacitors
• CPC Class Codes: H01L 28/56 the dielectric comprising two or more layers, e.g. comprising buffer layers, seed layers, gradient layers

Abstract

The formation of a barrier layer over a high k dielectric layer and deposition of a conducting layer over the barrier layer prevents intermigration between the species of the high k dielectric layer and the conducting layer and prevents oxygen scavenging of the high k dielectric layer. One example of a capacitor stack device provided includes a high k dielectric layer of Ta₂O₅, a barrier layer of TaON or TiON formed at least in part by a remote plasma process, and a top electrode of TiN. The processes may be conducted at about 300 to 700° C. and are thus useful for low thermal budget applications. Also provided are MIM capacitor constructions and methods in which an insulator layer is formed by remote plasma oxidation of a bottom electrode.

Claims

1. A method of making a barrier on a high k dielectric material, comprising the steps of:

providing a substrate having an upper surface comprising a high k dielectric material;

remotely generating a plasma using a nitrogen containing source;

flowing the plasma over the upper surface comprising a high k dielectric material to form an oxynitride layer on the upper surface;

remotely generating an oxygen plasma using a source of oxygen;

flowing the oxygen plasma over the oxynitride layer on the upper surface of the substrate to saturate and reduce species remaining in the oxynitride layer; and

annealing at least said upper surface of said substrate in an oxygen rich environment prior to said flowing the plasma.

2. The method of claim 1, wherein said high k dielectric material comprises Ta₂O_5.

3. The method of claim 2, wherein said nitrogen containing source comprises N₂ and said oxynitride layer comprises TaON.

4. The method of claim 3, wherein said flowing step is continued until said TaON layer is about 5 Å

thick.

5. The method of claim 2, wherein said nitrogen containing source comprises NH₃ and said oxynitride layer comprises TaON.

6. The method of claim 5, wherein said TaON layer is formed to a thickness of about 10 to 30 Å

.

7. The method of claim 1, further comprising the step of depositing a conducting layer over the oxynitride layer.

8. The method of claim 7, wherein said conducting layer is a top electrode.

9. The method of claim 7, wherein said conducting layer comprises TiN.

10. The method of claim 1, wherein the step of flowing the plasma over the upper surface comprising a high k dielectric material is conducted within a temperature range of about 300°

to 700°

C.

11. A method of making a barrier on a high k dielectric material, said method comprising the steps of:

providing a substrate having an upper surface comprising a high k dielectric material;

depositing a layer of TiN on said upper surface by chemical vapor deposition;

remotely generating a plasma using an oxygen containing source; and

flowing the plasma over the TiN layer to form an oxynitride layer on the upper surface.

12. The method of claim 11, further comprising the step of annealing at least said upper surface of said substrate in an oxygen rich environment prior to said depositing a layer of TiN.

13. The method of claim 11, wherein said depositing a TiN layer by chemical vapor deposition is carried out until said TiN layer achieves a thickness of about 30 to 50 Å

.

14. The method of claim 11, wherein said oxygen containing source is oxygen.

15. The method of claim 11, wherein said high k dielectric material comprises Ta₂O_5.

16. The method of claim 15, wherein said oxynitride layer comprises TaON.

17. The method of claim 11, further comprising the step of depositing a conducting layer over the oxynitride layer.

18. The method of claim 17, wherein said conducting layer is a top electrode.

19. The method of claim 17, wherein said conducting layer comprises TiN.

20. The method of claim 11, wherein the step of flowing the plasma over the TiN layer is conducted within a temperature range of about 300°

to 700°

C.

21. A method of making a high k dielectric from a top portion of a metallic layer, said method comprising the steps of:

providing a layer of metal nitride having a first metal to nitride atoms ratio;

depositing additional metal nitride while varying the metal to nitride atoms ratio during said depositing to form an additional thickness to said layer, wherein said additional thickness has a varying metal to nitride atoms ratio;

remotely generating a plasma using an oxygen containing source; and

flowing the plasma over the upper surface of the additional thickness of the metal nitride layer and diffusing oxygen into the additional thickness of the layer to form a metal oxynitride on an upper surface thereof.

22. The method of claim 21, wherein said metal nitride comprises tantalum nitride.

23. The method of claim 22, further comprising the step of depositing said tantalum nitride layer by physical vapor deposition, prior to said step of remotely generating a plasma.

24. A method of making a high capacitance density, MIM capacitor, comprising the steps of:

depositing a bottom electrode of tantalum nitride by physical vapor deposition;

remotely generating a plasma using an oxygen containing source;

flowing the plasma over the upper surface of the tantalum nitride layer and diffusing oxygen into the layer to form a tantalum oxynitride on the upper surface;

depositing a top electrode over the tantalum oxynitride; and

during said depositing of said bottom electrode, increasing the amount of nitrogen relative to tantalum, such that a ratio of N/Ta is greater in a top portion of said bottom electrode than a ratio of N/Ta in a portion of said bottom electrode underlying said top portion.