Gapfill improvement with low etch rate dielectric liners

• US 7,910,491 B2
• Filed: 05/07/2009
• Issued: 03/22/2011
• Est. Priority Date: 10/16/2008
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Soo Kwon, Young, Xia, Li-Qun, Wang, Anchuan, Jang, Bi, Lee, Young S., Balseanu, Mihaela, Jeon, Jin Ho
• Primary Examiner(s): Dickey; Thomas L
• Assistant Examiner(s): YUSHIN, NIKOLAY K
• Application Number:
  US12/437,256
• Publication Number:
  US 20100099236A1
• Time in Patent Office: 684 Days
• Field of Search: 438/9, 438/435, 438/443, 438/761, 438/705, 438/706, 438/738, 257/E21.546, 257/E21.24, 257/E21.396
• US Class Current: 438/738
• CPC Class Codes: H01L 21/02112 characterised by the material of the layer
• CPC Class Codes: H01L 21/02247 formation by nitridation, e.g. nitridation of the substrate
• CPC Class Codes: H01L 21/02304 formation of intermediate layers, e.g. buffer layers, layers to improve adhesion, lattice match or diffusion barriers
• CPC Class Codes: H01L 21/318 composed of nitrides
• CPC Class Codes: H01L 21/76224 using trench refilling with dielectric materials trench filling with polycristalline silicon H01L21/763; together with vertical isolation, e.g. trench refilling in a SOI substrate H01L21/76264

Abstract

A method of filling a trench is described and includes depositing a dielectric liner with a high ratio of silicon oxide to dielectric liner etch rate in fluorine-containing etch chemistries. Silicon oxide is deposited within the trench and etched to reopen or widen a gap near the top of the trench. The dielectric liner protects the underlying substrate during the etch process so the gap can be made wider. Silicon oxide is deposited within the trench again to substantially fill the trench.

Claims

1. A method of depositing dielectric material in a trench in a semiconductor substrate, the method comprising:

forming a liner layer comprising a bilayer, wherein the bilayer comprises a silicon nitride layer and a boron nitride layer over bottom and sidewall surfaces of the trench;

depositing the dielectric material comprising silicon oxide over the liner layer, wherein the dielectric material at least partially fills the trench; and

etching a portion of the deposited dielectric material with an etchant, wherein the etchant removes the dielectric material at a higher etch rate than the liner layer.

2. The method of claim 1, wherein the liner layer is a trilayer comprising a boron nitride layer formed between a pair of silicon nitride layers.

3. The method of claim 1, wherein the step of etching a portion of the deposited dielectric material exposes a void formed in the dielectric material in the trench.

4. The method of claim 3, wherein the method further comprises depositing a second portion of the dielectric material in the trench, wherein the second portion of dielectric material at least partially fills the exposed void.

5. The method of claim 1, wherein the step of etching a portion of the deposited dielectric material widens a gap formed by the dielectric material in the trench.

6. The method of claim 1, wherein the step of etching a portion of the deposited dielectric material involves a dry etch comprising reactive fluorine.

7. The method of claim 1, wherein the step of etching a portion of the deposited dielectric material comprises dry etching the dielectric material in a process gas comprising NH₃ and NF₃.

8. The method of claim 1, wherein the etchant comprises a reactive fluorine species formed from nitrogen trifluoride (NF₃).

9. A method of removing a void formed in a dielectric material that fills a trench in a semiconductor substrate, the method comprising:

etching a top portion of the dielectric material to expose an opening in the void, wherein the etching also exposes a portion of a liner layer comprising a bilayer, wherein the bilayer comprises a silicon nitride layer and a boron nitride layer that was covered by the dielectric material; and

depositing additional dielectric material into the exposed void to remove the void by filling it with the additional dielectric material.

10. A method of depositing a film to fill a gap in a surface of a substrate, the method comprising:

forming a dielectric liner on the surface of the substrate, wherein a silicon oxide to dielectric liner etch ratio is greater than about 50;

depositing a first layer of dielectric on the dielectric liner;

etching the surface of the substrate; and

depositing a second layer of dielectric to substantially fill the gap.

11. The method of claim 10, wherein the oxide to dielectric liner etch ratio is greater than about 75.

12. The method of claim 10, wherein the oxide to dielectric liner etch ratio is greater than about 100.

13. The method of claim 10, wherein the dielectric liner comprises boron nitride.

14. The method of claim 10, wherein the dielectric liner has an atomic concentration of boron which is greater than 5%.

15. The method of claim 10, wherein the dielectric liner has an atomic concentration of carbon which is greater than 5%.

16. The method of claim 10, wherein the dielectric liner has an atomic concentration of boron which is greater than 10%.

17. The method of claim 10, wherein the dielectric liner has an atomic concentration of carbon which is greater than 10%.

18. The method of claim 10, wherein the dielectric liner has an atomic concentration of boron which is greater than 20%.

19. The method of claim 10, wherein the dielectric liner has an atomic concentration of carbon which is greater than 20%.

20. The method of claim 10, wherein the dielectric liner comprises a material selected from the group consisting of boron carbide, boron oxide, silicon carbide, boron nitride, boron carbon nitride, phosphorous boron nitride, carbon nitride, silicon boron nitride, boron silicon oxide and silicon carbon nitride.

21. The method of claim 10, further comprising a step of forming a layer of silicon nitride before forming the conformal layer of boron nitride.

22. The method of claim 10, further comprising a step of forming a layer of silicon nitride before depositing the first layer of dielectric.

23. The method of claim 10, further comprising a step of forming a first layer of silicon nitride before forming the conformal layer of boron nitride and a second layer of silicon nitride before depositing the first layer of dielectric.

24. The method of claim 10, wherein the step of etching the substrate comprises dry etching the substrate in a process gas comprising NH₃ and NF₃.