Gas chemistry cycling to achieve high aspect ratio gapfill with HDP-CVD

• US 6,335,288 B1
• Filed: 08/24/2000
• Issued: 01/01/2002
• Est. Priority Date: 08/24/2000
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kwan, Michael, Liu, Eric
• Primary Examiner(s): Ghyka, Alexander G.
• Application Number:
  US09/648,395
• Time in Patent Office: 495 Days
• Field of Search: 438/694, 438/697, 438/784, 438/787, 438/788, 438/911, 427/585, 427/578, 427/579, 427/588
• US Class Current: 438/694
• CPC Class Codes: C23C 16/045 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• CPC Class Codes: C23C 16/4405 Cleaning of reactor or parts inside the reactor by using reactive gases
• CPC Class Codes: C23C 16/45523 Pulsed gas flow or change of composition over time
• CPC Class Codes: C23C 16/463 Cooling of the substrate
• CPC Class Codes: C23C 16/517 using a combination of discharges covered by two or more of groups C23C16/503 - C23C16/515
• CPC Class Codes: C23C 16/52 Controlling or regulating the coating process C23C16/45557, C23C16/279 take precedence
• CPC Class Codes: H01J 2237/3327 Coating high aspect ratio workpieces
• CPC Class Codes: H01J 2237/3347 bottom of holes or trenches
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01L 21/02131 the material being halogen doped silicon oxides, e.g. FSG
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/30655 comprising alternated and repeated etching and passivation steps, e.g. Bosch process
• CPC Class Codes: H01L 21/31608 Deposition of SiO2 H01L21/31625, H01L21/31629 and H01L21/31633 take precedence
• CPC Class Codes: H01L 21/31629 Deposition of halogen doped silicon oxide, e.g. fluorine doped silicon oxide
• CPC Class Codes: Y10S 438/911 Differential oxidation and etching

Abstract

A method and apparatus are disclosed for depositing a dielectric film in a gap having an aspect ratio at least as large as 6:1. By cycling the gas chemistry of a high-density-plasma chemical-vapor-deposition system between deposition and etching conditions, the gap may be substantially 100% filled. Such filling is achieved by adjusting the flow rates of the precursor gases such that the deposition to sputtering ratio during the deposition phases is within certain predetermined limits.

Claims

1. A method for depositing a dielectric film on a substrate in a process chamber, the method comprising:

(a) providing a first gaseous mixture to the process chamber, the first gaseous mixture comprising a first deposition gas and a first inert gas source;

(b) generating a first high-density plasma from the first gaseous mixture to deposit a first portion of the film on the substrate with a first deposition/sputter ratio within the range of 5-20, wherein the first deposition/sputter ratio is defined as a ratio of a sum of a first net deposition rate and a first blanket sputtering rate to the first blanket sputtering rate;

(c) thereafter, cooling the substrate;

(d) thereafter, flowing an etchant gas into the process chamber;

(e) thereafter, providing a second gaseous mixture to the process chamber, the second gaseous mixture comprising a second deposition gas and a second inert gas source; and

(f) generating a second high-density plasma from the second gaseous mixture to deposit a second portion of the film on the substrate, wherein the step of generating a second high-density plasma is performed with a second deposition/sputter ratio within the range of 5-20, wherein the second deposition/sputter ratio is defined as a ratio of a sum of a second net deposition rate and a second blanket sputtering rate to the second blanket sputtering rate.

2. The method according to claim 1 wherein the second gaseous mixture is substantially the same as the first gaseous mixture.

3. The method according to claim 1 wherein the first deposition/sputter ratio is in the range of 9-15.

4. The method according to claim 1 wherein the second deposition/sputter ratio is less than the first deposition/sputter ratio.

5. The method according to claim 1 wherein the etchant gas comprises remotely dissociated etchant atoms.

6. The method according to claim 5 wherein the remotely dissociated etchant atoms comprise fluorine atoms.

7. The method according to claim 6 wherein the fluorine atoms are provided by NF₃.

8. The method according to claim 1 further comprising the step of dissociating the etchant gas into dissociated etchant atoms within the process chamber.

9. The method according to claim 8 wherein the etchant gas is a fluorine-containing gas.

10. The method according to claim 8 wherein the etchant gas is NF₃.

11. The method according to claim 1 wherein the dielectric film is a silicon oxide film.

12. The method according to claim 1 wherein the dielectric film is a fluorinated silicon oxide film.

13. The method according to claim 1 wherein the dielectric film is deposited over a plurality of stepped surfaces formed on the substrate having gaps formed between adjacent ones of the stepped surfaces and wherein the first portion of the film partially fills the gaps.

14. The method according to claim 13 wherein the second portion of the film completes filling the gaps.

15. The method according to claim 1 wherein the step of cooling the substrate is performed external to the process chamber.