High density plasma CVD process for gapfill into high aspect ratio features

• US 6,802,944 B2
• Filed: 10/23/2002
• Issued: 10/12/2004
• Est. Priority Date: 10/23/2002
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kapoor, Bikram, Ahmad, Farhan, Jain, Alok, Awdshiew, Michael
• Primary Examiner(s): VERSTEEG, STEVEN H
• Application Number:
  US10/279,961
• Publication Number:
  US 20040079632A1
• Time in Patent Office: 720 Days
• Field of Search: 204/192.37, 204/192.32, 204/192.23, 216/63, 216/67, 216/80, 427/585, 427/331, 427/255.28, 427/578, 427/307, 427/314, 427/402, 427/534, 427/535
• US Class Current: 204/192.23
• CPC Class Codes: C23C 16/045 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• CPC Class Codes: C23C 16/401 containing silicon
• CPC Class Codes: C23C 16/505 using radio frequency discharges
• CPC Class Codes: H01L 21/02129 the material being boron or phosphorus doped silicon oxides, e.g. BPSG, BSG or PSG
• 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 21/31612 on a silicon body
• CPC Class Codes: H01L 21/31625 Deposition of boron or phosphorus doped silicon oxide, e.g. BSG, PSG, BPSG
• CPC Class Codes: H01L 21/31633 Deposition of carbon doped silicon oxide, e.g. SiOC
• CPC Class Codes: H01L 21/76837 Filling up the space between adjacent conductive structures; Gap-filling properties of dielectrics

Abstract

A method of depositing a film on a substrate. In one embodiment, the method includes depositing a first portion of the film using a high density plasma to partially fill a gap formed between adjacent features formed on the substrate. The film deposition process is then stopped before or shortly after the entry of the gap pinches off and the film is etched to widen entry to the gap using a two step etching process that includes a first physical etch step that forms a plasma from a sputtering agent introduced into the processing chamber and biases the plasma towards the substrate and a subsequent chemical etch step that forms a plasma from a reactive etchant gas introduced into the processing chamber. After the etching sequence is complete, a second portion of the film is deposited over the first portion using a high density plasma to further fill the gap.

Claims

1. A method of depositing a film on a substrate disposed in a substrate processing chamber, the method comprising:

depositing a first portion of the film over the substrate by forming a high density plasma from a first gaseous mixture flown into the process chamber;

thereafter, sputter etching part of the deposited first portion of the film by forming a plasma from a sputtering agent introduced into the processing chamber and biasing the plasma towards the substrate;

thereafter, chemically etching part of the deposited first portion of the film by forming a plasma from a reactive etchant gas introduced into the processing chamber; and

thereafter, depositing a second portion of the film over the first portion by forming a high density plasma from a second gaseous mixture flown into the process chamber.

2. The method of claim 1 wherein the bias power is switched OFF during the chemical etching step.

3. The method of claim 1 wherein the first and second gaseous mixtures are silica glass deposition gases.

4. The method of claim 3 wherein the first and second gaseous mixtures each comprise silane and oxygen.

5. The method of claim 1 wherein the sputter etching includes a flow of a reactive etchant gas that is less than a flow of the reactive etchant gas in the chemical etch.

6. The method of claim 5 wherein the reactive etchant flowed into the chamber in the sputter etch and chemical etch is the same gas and wherein the flow rate of the reactive etchant is at least 300 percent higher in the chemical etch than in the sputter etch.

7. The method of claim 6 wherein the flow rate of the reactive etchant is at least 500 percent higher in the chemical etch than in the sputter etch.

8. The method of claim 6 wherein the reactive etchant is a fluorine-containing gas.

9. The method of claim 6 wherein the sputter etch and chemical etch each include a flow of an oxygen-containing gas.

10. A method of depositing a silica glass film on a substrate disposed in a substrate processing chamber, the substrate having a trench formed between adjacent raised surfaces, the method comprising, in order:

depositing a first portion of the silica glass film over the substrate and within the trench by forming a high density plasma process that has simultaneous deposition and sputtering components from a first deposition gas comprising a silicon source and an oxygen source;

stopping deposition of the silica glass film and sputter etching the first portion of the film by biasing a high density plasma formed from a sputtering agent introduced into the processing chamber towards the substrate;

thereafter, chemically etching the first portion of the film with reactive species formed from an etchant gas; and

thereafter, depositing a second portion of the silica glass film over the substrate and within the trench by forming a high density plasma process that has simultaneous deposition and sputtering components from a second deposition gas comprising a silicon source and an oxygen source.

11. The method of claim 10 wherein the high density plasma is continuously maintained between depositing a first position of the silica glass film and the sputter etching.

12. The method of claim 11 wherein the reactive species in the chemically etching the first portion of the film are dissociated remotely from a fluorine etchant gas and transported into the chamber.

13. The method of claim 11 wherein the reactive species in the chemically etching the first portion of the film are generated within the chamber by a high density plasma.

14. The method of claim 13 wherein the high density plasma is continuously maintained between depositing a first portion of the silica glass film and depositing a second portion of the silica glass film.

15. The method of claim 14 wherein the reactive etchant flowed into the chamber in the sputter etch and chemical etch is the same gas and wherein the flow rate of the reactive etchant is at least 300 percent higher in the chemical etch than in the sputter etch.

16. The method of claim 15 wherein the sputter etch and chemical etch each include a flow of an oxygen-containing gas.

17. The method of claim 16 further comprising, after chemically etching the first portion of the film, exposing the first portion of the film to a passivation gas consisting of an oxygen source with or without an inert gas.

18. The method of claim 16 wherein the trench is part of a shallow trench isolation structure formed on a silicon substrate.

19. The method of claim 16 wherein the silicon source in the first and second deposition gases comprises monosilane (SiH₄).

20. The method of claim 19 wherein the oxygen source in the first and second deposition gases comprises molecular oxygen (O₂).

21. The method of claim 20 wherein the first and second deposition gases each further comprise an inert gas as a sputtering component.

22. The method of claim 16 wherein the plasma is not biased towards the substrate while chemically etching the first portion of the film.

23. The method of claim 10 wherein the sputter etching etches at least two and a half times more of the silica glass film over the raised surfaces than at a bottom of the trench.

24. The method of claim 10 wherein the sputter etching etches at least five times more of the silica glass film over the raised surfaces than at a bottom of the trench.

25. The method of claim 10 wherein the sputter etching etches at least ten times more of the silica glass film over the raised surfaces than at a bottom of the trench.

26. A method of depositing a silica glass film on a substrate disposed in a substrate processing chamber, the substrate having a trench formed between adjacent raised surfaces, the method comprising:

forming a high density plasma within the substrate processing chamber to heat the substrate to a temperature of at least 400°

C. prior to depositing the silica glass film on the substrate;

maintaining the high density plasma while (i) flowing a first process gas comprising a silicon source and an oxygen source into the processing chamber to deposit a first portion of the silica glass film over the substrate and in the trench using a deposition process that has simultaneous deposition and sputtering components, (ii) flowing a sputtering gas comprising an inert gas, an oxygen source and a fluorine etchant into the process chamber while biasing the plasma towards the substrate to sputter etch the first portion of the silica glass film;

(iii) switching off bias power that biases the plasma towards the substrate and flowing a fluorine etchant and oxygen source into the chamber in order to chemically etch the first portion of the silica glass film, wherein a flow rate of the fluorine etchant is at least 300 percent higher than a flow rate of the fluorine etchant in the sputter etch; and

(iv) flowing a second process gas comprising a silicon source and an oxygen source into the processing chamber to deposit a second portion of the silica glass film over the first portion using a deposition process that has simultaneous deposition and sputtering components.

27. The method of claim 26 wherein the sputter etch and chemical etch each include a flow of an oxygen-containing gas.

28. The method of claim 27 wherein the trench is part of a shallow trench isolation structure formed on a silicon substrate.

29. The method of claim 26 wherein the sputter etching etches at least two and a half times more of the silica glass film over the raised surfaces than at a bottom of the trench.

30. The method of claim 26 wherein the sputter etching etches at least five times more of the silica glass film over the raised surfaces than at a bottom of the trench.

31. The method of claim 26 wherein the sputter etching etches at least ten times more of the silica glass film over the raised surfaces than at a bottom of the trench.