Controlling the properties and uniformity of a silicon nitride film by controlling the film forming precursors

• US 7,125,758 B2
• Filed: 04/20/2004
• Issued: 10/24/2006
• Est. Priority Date: 04/20/2004
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Furuta, Gaku, Park, Beom Soo, Choi, Soo Young, Won, Tae Kyung, White, John M., Wang, Qunhua
• Primary Examiner(s): Smoot, Stephen W.
• Application Number:
  US10/829,016
• Publication Number:
  US 20050233595A1
• Time in Patent Office: 917 Days
• Field of Search: 438/792
• US Class Current: 438/151
• CPC Class Codes: C23C 16/345 Silicon nitride
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/3185 of siliconnitrides
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/66765 Lateral single gate single channel transistors with inverted structure, i.e. the channel layer is formed after the gate
• CPC Class Codes: H01L 29/78669 with inverted-type structure, e.g. with bottom gate

Abstract

We have developed a method of PECVD depositing a-SiN_x:H films which are useful in a TFT device as gate dielectric and passivation layers, when a series of TFT devices are arrayed over a substrate having a surface area larger than about 1 m², which may be in the range of about 4.1 m², and even as large as 9 m². The a-SiN_x:H films provide a uniformity of film thickness and uniformity of film properties, including chemical composition, which are necessary over such large substrate surface areas. The films produced by the method are useful for both liquid crystal active matrix displays and for organic light emitting diode control.

Claims

1. A method of PECVD depositing an a-SiN_x:

H dielectric film useful in a TFT device as gate dielectric, when a series of TFT devices are arrayed over a substrate having a surface area larger than about 1 m², said method comprising;

depositing said a-SiN_x;

H dielectric film over a substrate which is at a temperature ranging from about 120°

C. to about 340°

C.;

depositing said a-SiN_x;

H dielectric film at a process pressure which ranges between about 1.0 Torr to about 2.0 Torr;

depositing said a-SiN_x;

H dielectric film from precursors including N₂, NH₃, and SiH 4, and wherein a component ratio of NH₃/SiH₄ ranges from about 5.3 to about 10.0, a component ratio of N₂/SiH₄ ranges from about 5.5 to about 18.7, and a component ratio of N₂/NH₃ ranges from about 0.6 to about 2.3; and

applying a plasma to a mixture of said precursors, so that the plasma density in a process chamber in which said a-SiN_x;

H dielectric film is deposited ranges between about 0.2 W/cm² and about 0.6 W/cm².

2. A method in accordance with claim 1, wherein an electrode spacing in said process chamber ranges from about 400 mils to about 1000 mils.

3. A method in accordance with claim 1 or claim 2, wherein said substrate temperature ranges from about 240°

C. to about 320°

C.

4. A method in accordance with claim 1 or claim 2, wherein said pressure in said process chamber ranges from about 1.0 Torr to about 1.5 Torr.

5. A method in accordance with claim 1, wherein said substrate surface area is larger than about 2.7m².

6. A method in accordance with claim 5, wherein said substrate surface area is larger than about 4.1 m².

7. A method in accordance with claim 6, wherein said substrate surface area is larger than about 9.0 m².

8. A method in accordance with claim 1, wherein said substrate surface area ranges between about 1.0 m² and about 4.1 m².

9. A method in accordance with claim 1, wherein a deposition rate of said a-SiN_x:

H dielectric film is at least 1000 Å

/min.

10. A method in accordance with claim 9, wherein said deposition rate is at least 1300 Å

/min.

11. A method in accordance with claim 10, wherein said deposition rate is at least 1,600 Å

/min.

12. A method in accordance with claim 11, wherein said deposition rate is at least 2300 Å

/min.

13. A method in accordance with claim 12, wherein said deposition rate is at least 3000 Å

/min.

14. A method in accordance with claim 1, wherein a deposition rate of said a-SiN_x:

H dielectric film ranges between about 1000 Å

/min and 2300 Å

/min.

15. A method in accordance with claim 1, wherein the variation in said film thickness over said substrate is less than about 16%.

16. A method in accordance with claim 1, or claim 15, wherein the atomic % of Si-H bonded structure is less than about 20%.

17. A method in accordance with claim 16, wherein the atomic % of Si-H bonded structure is less than about 15%.

18. A method in accordance with claim 1, wherein a wet etch rate of said film in a solution of 7%. by weight hydrofluoric acid, 34% by weight aminonium fluoride, and 59% by weight water at a temperature of about 25°

C. is less than 800 Å

/min.

19. A method of PECVD depositing an a-SiN_x:

H dielectric film useful in a TFT device as a passivation dielectric, when a series of TFT devices are arrayed over a substrate having a surface area larger than about 1 m², said method comprising;

depositing said a-SiN_x;

H dielectric film over a substrate which is at a temperature ranging from about 120°

C. to about 340°

C.;

depositing said a-SiN_x;

H dielectric film at a process pressure which ranges between about 1.0 Torr to about 2.0 Torr;

depositing said a-SiN_x;

H dielectric film from precursors including N₂, NH₃, and SiH4, and wherein a component ratio of NH₃/SiH₄ ranges from about 5.3to about 11.1, a component ratio of N₂/SiH₄ ranges from about 5.8 to about 20.8 and a component ratio of N₂/NH₃ ranges from about 0.5 to about 3.9; and

applying a plasma to a mixture of said precursors, so that the plasma density in a process chamber in which said a-SiN_x;

H dielectric film is deposited ranges between about 0.2W/cm²and about 0.6W/cm².

20. A method in accordance with claim 19, wherein an electrode spacing in said process chamber ranges from about 400 mils to about 1000 mils.

21. A method in accordance with claim 19 or claim 20, wherein said substrate temperature ranges from about 240 °

C. to about 320 °

C.

22. A method in accordance with claim 19 or claim 20, wherein said pressure in said process chamber ranges from about 1.0 Torr to about 1.5 Torr.

23. A method of PECVD depositing an a-SiN_x:

H dielectric film useful in a TFT device as a passivation dielectric, when a series of TFT devices are arrayed over a substrate having a surface area larger than about 1 m², said method comprising;

depositing said a-SiN_x;

H dielectric film over a substrate which is at a temperature ranging from about 120°

C. to about 340°

C.;

depositing said a-SiN_x;

H dielectric film at a process pressure which ranges between about 1.0 Torr to about 2.0 Torr;

depositing said a-SiN_x;

H dielectric film from precursors including N₂, NH₃, and SiH4, and wherein a component ratio of NH₃/SiH₄ ranges from about 5.0 to about 8.0, a component ratio of N₂/SiH₄ ranges from about 5.0 to about 6.0 and a component ratio of N₂/NIH₃ ranges from about 0.6 to about 1.2; and

applying a plasma to a mixture of said precursors, so that the plasma density in a process chamber in which said a-SiN_x;

H dielectric film is deposited ranges between about 0.2W/cm²and about 0.6W/cm².