Method of controlling the film properties of a CVD-deposited silicon nitride film

• US 20060019502A1
• Filed: 07/23/2004
• Published: 01/26/2006
• Est. Priority Date: 07/23/2004
• Status: Abandoned Application

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Park, Beom Soo, Choi, Soo Young, Won, Tae Kyung, White, John M.
• Application Number:
  US10/897,775
• Publication Number:
  US 20060019502A1
• Time in Patent Office: Days
• US Class Current: 438/791
• CPC Class Codes: C23C 16/345 Silicon nitride
• CPC Class Codes: C23C 16/5096 Flat-bed apparatus
• 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 21/02208 the precursor containing a compound comprising Si
• 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

Abstract

We have discovered that adding H₂ to a precursor gas composition including SiH₄, NH₃, and N₂ is effective at improving the wet etch rate and the wet etch rate uniformity across the substrate surface of a-SiN_x:H films which are deposited on a substrate by PECVD. Wet etch rate is an indication of film density. Typically, the lower the wet etch rate, the denser the film. The addition of H₂ to the SiH₄/NH₃/N₂ precursor gas composition did not significantly increase the variation in deposited film thickness across the surface of the substrate. The a-SiN_x:H films described herein are particularly useful as TFT gate dielectrics in the production of flat panel displays. The uniformity of the film across the substrate enables the production of flat panel displays having surface areas of 25,000 cm² and larger.

Claims

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

H film, said method comprising;

depositing said a-SiN_x;

H dielectric film over a substrate which is at a temperature within the range of about 250°

C. to about 450°

C.;

depositing said a-SiN_x;

H dielectric film at a process pressure within the range of about 0.5 Torr to about 3 Torr;

depositing said a-SiN_x;

H dielectric film from a precursor gas composition including N₂, NH₃, SiH₄, and H₂, wherein H₂ is provided to said process chamber H is provided to the deposition chamber in an amount such that a component ratio of NH₃;

H₂ in said plasma precursor gas composition ranges from about 1;

2 to about 3;

1; 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 is within the range of about 0.1 W/cm² to about 1 W/cm².

2. A method in accordance with claim 1, wherein a component ratio of NH₃:

H₂ in said plasma precursor gas composition ranges from about 1;

1 to about 3;

1.

3. A method in accordance with claim 1, wherein a component ratio of NH₃:

SiH₄ in said plasma precursor gas composition ranges from about 2;

1 to about 15;

1, a component ratio of N₂;

SiH₄ ranges from about 5;

1 to about 25;

1, and a component ratio of NH₃;

N₂ ranges from about 1;

3 to about 2;

1.

4. A method in accordance with claim 1, wherein an electrode spacing in said process chamber is within the range of about 400 mils to about 1000 mils.

5. A method in accordance with claim 1, wherein said substrate temperature during film deposition is within the range of about 300°

C. to about 400°

C.

6. A method in accordance with claim 1, wherein said substrate temperature during film deposition is within the range of about 320°

C. to about 360°

C.

7. A method in accordance with claim 1, wherein said pressure in said process chamber during film deposition is within the range of about 1 Torr to about 1.5 Torr.

8. A method in accordance with claim 1, wherein said substrate surface area is larger than about 25,000 cm².

9. A method in accordance with claim 8, wherein said substrate surface area is larger than about 40,000 cm².

10. A method in accordance with claim 1, wherein the variation in said film thickness over said substrate is less than about 20%.

11. A method in accordance with claim 12, wherein the variation in said film thickness over said substrate is less than about 17%.

12. A method in accordance with claim 13, wherein the variation in said film thickness over said substrate is less than about 15%.

13. A method in accordance with claim 1, wherein the atomic % of Si—

H bonded structure is less than about 15%, and wherein said atomic % of Si—

H bonded structure is measured at the center of said substrate.

14. A method in accordance with claim 15, wherein the atomic % of Si—

H bonded structure is less than about 13%, and wherein said atomic % of Si—

H bonded structure is measured at the center of said substrate.

15. A method in accordance with claim 16, wherein the atomic % of Si—

H bonded structure is less than about 10%, and wherein said atomic % of Si—

H bonded structure is measured at the center of said substrate.

16. 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 ammonium fluoride, and 59% by weight water at a temperature of about 25°

C. is less than 800 Å

/min.

17. A method in accordance with claim 18, wherein said wet etch rate is less than 500 Å

/min.

18. A method in accordance with claim 19, wherein said wet etch rate is less than 400 Å

/min.

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

C. is less than 15% across the surface of said substrate.

20. A PECVD apparatus which includes instructions for depositing an a-SiN_x:

H film according to a method comprising;

depositing said a-SiN_x;

H dielectric film over a substrate which is at a temperature within the range of about 250°

C. to about 450°

C.;

depositing said a-SiN_x;

H dielectric film at a process pressure within the range of about 0.5 Torr to about 3 Torr;

depositing said a-SiN_x;

H dielectric film from a precursor gas composition including N₂, NH₃, SiH₄, and H₂, wherein H₂ is provided to said process chamber H₂ is provided to the deposition chamber in an amount such that a component ratio of NH₃;

H₂ in said plasma precursor gas composition ranges from about 1;

2 to about 3;

1; 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 is within the range of about 0.1 W/cm² to about 1 W/cm².