Method of forming a dielectric film

• US 6,866,890 B2
• Filed: 03/22/2001
• Issued: 03/15/2005
• Est. Priority Date: 03/30/2000
• Status: Expired due to Fees

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Kiryu, Hideki, Takahashi, Tsuyoshi, Aoyama, Shintaro, Shinriki, Hiroshi
• Primary Examiner(s): Chen, Bret
• Application Number:
  US10/239,648
• Publication Number:
  US 20040005408A1
• Time in Patent Office: 1,454 Days
• Field of Search: 427/255.31, 427/255.34, 427/255.36, 427/255.7, 438/761, 438/253, 438/769
• US Class Current: 427/255.31
• CPC Class Codes: C23C 16/0218 in a reactive atmosphere C23C16/0227 takes precedence
• CPC Class Codes: C23C 16/0227 by cleaning or etching
• CPC Class Codes: C23C 16/0236 by etching with a reactive gas
• CPC Class Codes: C23C 16/0272 Deposition of sub-layers, e.g. to promote the adhesion of the main coating
• CPC Class Codes: C23C 16/401 containing silicon
• CPC Class Codes: C23C 16/403 of aluminium, magnesium or beryllium
• CPC Class Codes: C23C 16/405 of refractory metals or yttrium
• CPC Class Codes: C23C 16/45525 Atomic layer deposition [ALD]
• CPC Class Codes: H01L 21/02178 the material containing aluminium, e.g. Al2O3
• CPC Class Codes: H01L 21/02181 the material containing hafnium, e.g. HfO2
• CPC Class Codes: H01L 21/02183 the material containing tantalum, e.g. Ta2O5
• CPC Class Codes: H01L 21/02189 the material containing zirconium, e.g. ZrO2
• CPC Class Codes: H01L 21/022 the layer being a laminate, i.e. composed of sublayers, e.g. stacks of alternating high-k metal oxides adhesion layers or buffer layers H01L21/02304, H01L21/02362
• CPC Class Codes: H01L 21/02238 silicon in uncombined form, i.e. pure silicon
• CPC Class Codes: H01L 21/02271 deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition H01L21/02266 takes precedence
• CPC Class Codes: H01L 21/28185 with a treatment, e.g. annealing, after the formation of the gate insulator and before the formation of the definitive gate conductor
• CPC Class Codes: H01L 21/28194 by deposition, e.g. evaporation, ALD, CVD, sputtering, laser deposition H01L21/28202 takes precedence
• CPC Class Codes: H01L 21/31604 Deposition from a gas or vapour H01L21/31691, H01L21/31695 take precedence
• CPC Class Codes: H01L 21/31683 of metallic layers, e.g. Al deposited on the body, e.g. formation of multi-layer insulating structures
• CPC Class Codes: H01L 28/56 the dielectric comprising two or more layers, e.g. comprising buffer layers, seed layers, gradient layers
• CPC Class Codes: H01L 29/513 : the variation being perpendicular to the channel plane
• CPC Class Codes: H01L 29/517 : the insulating material comprising a metallic compound, e.g. metal oxide, metal silicate H01L29/518 takes precedence

Abstract

A method of forming a dielectric film on a Si substrate comprises the steps of adsorbing a gaseous molecular compound of a metal element constituting a dielectric material on a Si substrate, and causing a decomposition of the gaseous molecular compound thus adsorbed by a hydrolysis process or pyrolytic decomposition process or an oxidation process.

Claims

1. A method of forming a dielectric film on a Si substrate, comprising the steps of:

exposing a surface of said Si substrate;

forming an insulating layer on said exposed surface of said Si substrate;

causing an adsorption of a gaseous molecular compound of a metal element constituting a dielectric material at least once on a surface of said insulating layer, such that said gaseous molecular compound covers substantially uniformly over said insulating layer; and

forming a molecular layer of said dielectric material containing said metal element on said insulating layer, by causing a hydrolysis of said gaseous molecular compound covering said insulating layer.

2. A method as claimed in claim 1, wherein said dielectric material comprises Ta₂O₅ and wherein said gaseous molecular compound comprises any of Ta(OC₂H₅)₅ and TaCl₅.

3. A method as claimed in claim 1, wherein said dielectric material comprises ZrO₂ and wherein said gaseous molecular compound comprises any of Zr(t-OC₄H₉)₄ and ZrCl₄.

4. A method as claimed in claim 1, wherein said dielectric material comprises HfO₂ and wherein said gaseous molecular compound comprises any of Hf(t-OC₄H₉)₄ and HfCl₄.

5. A method as claimed in claim 1, wherein said dielectric material comprises Al₂O₃ and wherein said gaseous molecular compound comprises any of Al(i-OC₃H₇)₃ and (CH₃)₃Al.

6. A method as claimed in claim 1, wherein said step of forming said insulating layer comprises the steps of:

covering said exposed surface of said Si substrate substantially uniformly by a gaseous molecular compound of Si at least once, by adsorbing said gaseous molecular compound of Si on said exposed surface of said Si substrate; and

causing a hydrolysis of said gaseous molecular compound of Si, said gaseous molecular compound of Si being selected from the group consisting of SiCl₄, SiH₂Cl₂ and Si(C₂H₅)₄.

7. A method as claimed in claim 1, wherein said step of forming said insulating layer on said Si substrate comprises the step of applying a thermal oxidation process to said exposed surface of said Si substrate.

8. A method as claimed in claim 1 further comprising the step of forming, after said step of hydrolysis, a high-dielectric film on said molecular layer of said dielectric material by a CVD process.

9. A method as claimed in claim 1, wherein said step of forming said molecular layer of said dielectric material comprises the step of forming a dielectric film having a composition represented as ZrSiO₄, such that said dielectric film has a low Zr concentration level at an interface to said Si substrate and such that said Zr concentration level increases with increasing distance from said interface.

10. A method as claimed in claim 9, wherein said step of forming said dielectric film comprises the steps of forming a SiO₂ molecular layer and a ZrO₂ molecular layer consecutively, said step of forming said SiO₂ molecular layer comprising the steps of:

adsorbing molecules of a first gaseous source material containing Si on an underlying layer; and

decomposing said adsorbed molecules of said first gaseous source material, said step of forming said ZrO₂ molecular layer comprising the steps of;

adsorbing molecules of a second gaseous source material containing Zr on an underlying layer; and

decomposing said adsorbed molecules of said second gaseous source material.

11. A method of forming a dielectric film on a Si substrate, comprising the steps of:

exposing a surface of said Si substrate;

forming an insulating layer on said exposed surface of said Si substrate;

causing an adsorption of a gaseous molecular compound of a metal element constituting a dielectric material at least once on said insulating layer, such that said gaseous molecular compound covers substantially uniformly over said insulating layer; and

forming a molecular layer of said dielectric material containing said metal element on said insulating layer, by causing a pyrolytic decomposition of said gaseous molecular compound covering said insulating layer,

said step of causing a pyrolytic decomposition comprising the step of heating said Si substrate to a temperature exceeding a pyrolytic decomposition temperature of said gaseous molecular compound in an oxidizing atmosphere.

12. A method as claimed in claim 11, wherein said dielectric material comprises Ta₂O₅ and wherein said gaseous molecular compound comprises any of Ta(OC₂H₅)₅ and TaCl₅.

13. A method as claimed in claim 11, wherein said dielectric material comprises ZrO₂ and wherein said gaseous molecular compound comprises any of Zr(t-OC₄H₉)₄ and ZrCl₄.

14. A method as claimed in claim 11, wherein said dielectric material comprises HfO₂ and wherein said gaseous molecular compound comprises any of Hf(t-OC₄H₉)₄ and HfCl₄.

15. A method as claimed in claim 11, wherein said dielectric material comprises Al₂O₃ and wherein said gaseous molecular compound comprises any of Al(i-OC₃H₇)₃ and (CH₃)₃Al.

16. A method as claimed in claim 11, wherein said step of forming said insulating layer comprises the steps of:

covering said exposed surface of said Si substrate substantially uniformly by a gaseous molecular compound of Si at least once, by adsorbing said gaseous molecular compound of Si on said exposed surface of said Si substrate; and

causing a hydrolysis of said gaseous molecular compound of Si, said gaseous molecular compound of Si being selected from the group consisting of SiCl₄, SiH₂Cl₂ and Si(C₂H₅)₄.

17. A method as claimed in claim 11, wherein said step of forming said insulating layer on said Si substrate comprises the step of applying a thermal oxidation process to said exposed surface of said Si substrate.

18. A method as claimed in claim 11 further comprising the step of forming, after said step of pyrolytic decomposition, a high-dielectric film on said molecular layer of said dielectric material by a CVD process.

19. A method as claimed in claim 11, wherein said step of forming said molecular layer of said dielectric material comprises the step of forming a dielectric film having a composition represented as ZrSiO₄, such that said dielectric film has a low Zr concentration level at an interface to said Si substrate and such that said Zr concentration level increases with increasing distance from said interface.

20. A method as claimed in claim 19, wherein said step of forming said dielectric film comprises the steps of forming a SiO₂ molecular layer and a ZrO₂ molecular layer consecutively, said step of forming said SiO₂ molecular layer comprising the steps of:

adsorbing molecules of a first gaseous source material containing Si on an underlying layer; and

decomposing said adsorbed molecules of said first gaseous source material, said step of forming said ZrO₂ molecular layer comprising the steps of;

adsorbing molecules of a second gaseous source material containing Zr on an underlying layer; and

decomposing said adsorbed molecules of said second gaseous source material.

21. A method of forming a dielectric film on a Si substrate, comprising the steps of:

exposing a surface of said Si substrate;

forming an insulating layer on said exposed surface of said Si substrate;

causing an adsorption of a gaseous molecular compound of a metal element constituting a dielectric material at least once on said insulating layer, such that said gaseous molecular compound covers substantially uniformly over said insulating layer; and

forming a molecular layer of said dielectric material containing said metal element on said insulating layer, by exposing said gaseous molecular compound to an atmosphere selected from the group consisting of H₂O, O₃ and NO₂.

22. A method as claimed in claim 21, wherein said dielectric material comprises Ta₂O₅ and wherein said gaseous molecular compound comprises any of Ta(OC₂H₅)₅ and TaCl₅.

23. A method as claimed in claim 21, wherein said dielectric material comprises ZrO₂ and wherein said gaseous molecular compound comprises any of Zr(t-OC₄H₉)₄ and ZrCl₄.

24. A method as claimed in claim 21, wherein said dielectric material comprises HfO₂ and wherein said gaseous molecular compound comprises any of Hf(t-OC₄H₉)₄ and HfCl₄.

25. A method as claimed in claim 21, wherein said dielectric material comprises Al₂O₃ and wherein said gaseous molecular compound comprises any of Al(i-OC₃H₇)₃ and (CH₃)₃Al.

26. A method as claimed in claim 21, wherein said step of forming said insulating layer comprises the steps of:

covering said exposed surface of said Si substrate substantially uniformly by a gaseous molecular compound of Si at least once, by adsorbing said gaseous molecular compound of Si on said exposed surface of said Si substrate; and

causing a hydrolysis of said gaseous molecular compound of Si, said gaseous molecular compound of Si being selected from the group consisting of SiCl₄, SiH₂Cl₂ and Si(C₂H₅)₄.

27. A method as claimed in claim 21, wherein said step of forming said insulating layer on said Si substrate comprises the step of applying a thermal oxidation process to said exposed surface of said Si substrate.

28. A method as claimed in claim 21 further comprising the step of forming, after said step of exposure to said atmosphere, a high-dielectric film on said molecular layer of said dielectric material by a CVD process.

29. A method as claimed in claim 21, wherein said step of forming said molecular layer of said dielectric material comprises the step of forming a dielectric film having a composition represented as ZrSiO₄, such that said dielectric film has a low Zr concentration level at an interface to said Si substrate and such that said Zr concentration level increases with increasing distance from said interface.

30. A method as claimed in claim 29, wherein said step of forming said dielectric film comprises the steps of forming a SiO₂ molecular layer and a ZrO₂ molecular layer consecutively, said step of forming said SiO₂ molecular layer comprising the steps of:

adsorbing molecules of a first gaseous source material containing Si on an underlying layer; and

decomposing said adsorbed molecules of said first gaseous source material, said step of forming said ZrO₂ molecular layer comprising the steps of;

adsorbing molecules of a second gaseous source material containing Zr on an underlying layer; and

decomposing said adsorbed molecules of said second gaseous source material.