Polysilicon films by HDP-CVD

• US 8,450,191 B2
• Filed: 04/19/2011
• Issued: 05/28/2013
• Est. Priority Date: 01/24/2011
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Wang, Anchuan, Chen, Xiaolin, Lee, Young S.
• Primary Examiner(s): Roman, Angel
• Application Number:
  US13/089,966
• Publication Number:
  US 20120190178A1
• Time in Patent Office: 770 Days
• Field of Search: 438/479, 257/E21.09, 257/E21.294
• US Class Current: 438/479
• CPC Class Codes: C23C 16/0245 by etching with a plasma
• CPC Class Codes: C23C 16/045 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• CPC Class Codes: C23C 16/24 Deposition of silicon only
• CPC Class Codes: H01L 21/02529 Silicon carbide
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02573 Conductivity type
• CPC Class Codes: H01L 21/02595 polycrystalline
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/28556 by chemical means, e.g. CVD, LPCVD, PECVD, laser CVD H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence

Abstract

Methods of forming polysilicon layers are described. The methods include forming a high-density plasma from a silicon precursor in a substrate processing region containing the deposition substrate. The described methods produce polycrystalline films at reduced substrate temperature (e.g. <500° C.) relative to prior art techniques. The availability of a bias plasma power adjustment further enables adjustment of conformality of the formed polysilicon layer. When dopants are included in the high density plasma, they may be incorporated into the polysilicon layer in such a way that they do not require a separate activation step.

Claims

1. A method of depositing a polysilicon layer in a trench of a patterned substrate in a substrate processing region of a substrate processing, chamber, the method comprising:

transferring the patterned substrate into the substrate processing region;

growing the polysilicon layer on the patterned substrate by forming a high density plasma in the substrate processing region from a deposition process gas comprising a silicon source while maintaining a mean pressure within the substrate processing region of about 20 mTorr or less and maintaining a mean patterned substrate temperature of 500°

C. or less,

wherein the process gas further comprises a doping source which provides a dopant to the polysilicon layer during growth, wherein the dopant is already activated upon formation of the polysilicon layer;

removing the patterned substrate from the substrate processing region.

2. The method of claim 1, further comprising pretreating the patterned substrate in a high density plasma in the substrate processing region from a pretreatment process gas comprising a hydrogen source before growing the polysilicon layer on the patterned substrate.

3. The method of claim 1, wherein essentially no bias is applied between the patterned substrate and the high density plasma while growing the polysilicon layer such that the polysilicon layer is essentially conformal.

4. The method of claim 3, wherein a growth rate of the polysilicon layer is below about 500 Å

/minute.

5. The method of claim 3, wherein a horizontal growth rate of the polysilicon layer as measured on a wall of the trench is between about 50% and 100% of a vertical growth rate, on a surface around the opening of the trench.

6. The method of claim 1, wherein a plasma bias power is applied between the patterned substrate and the high density plasma while growing the polysilicon layer such that the trench fills with polysilicon.

7. The method of claim 1, wherein the silicon source is silane.

8. The method of claim 1, wherein the process gas further comprises a fluent gas selected from argon, neon, and helium flowed with a fourth flow rate during the growth of at least one of the two layers.

9. The method of claim 1, wherein the mean patterned substrate temperature is less than or about 400°

C.

10. The method of claim 1, wherein the process gas further comprises a source of phosphorous or boron.

11. The method of claim 1, wherein the process gas comprises PH₃ flowed at a fourth gas flow rate.

12. The method of claim 1, wherein a deposition-to-sputter ratio during growth of the polysilicon layer is between about 2:

1 and 6;

1.

13. The method of claim 1, wherein the interior of the substrate processing region is seasoned with silicon oxide prior to the operation of transferring the patterned substrate into the substrate processing region.

14. The method of claim 13, wherein seasoning the interior of the substrate processing region comprises forming a high density plasma in the substrate processing region from a seasoning process gas comprising an oxygen source and a silicon source.

15. The method of claim 14, wherein the oxygen source is diatomic oxygen (O₂) and the silicon source is silane (SiH₄).

16. The method of claim 1, wherein the process gas further comprises a source of carbon and the polysilicon layer is a carbon-doped polysilicon layer.