Method for etching chemically inert metal oxides

• US 20030230549A1
• Filed: 06/13/2002
• Published: 12/18/2003
• Est. Priority Date: 06/13/2002
• Status: Active Grant

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Gousev, Evgeni, Okorn-Schmidt, Harald, Cartier, Eduard A., Saenger, Katherine L., Buchanan, Douglas A.
• Granted Patent: US 7,887,711 B2
• Time in Patent Office: Days
• US Class Current: 216/41
• CPC Class Codes: H01L 21/31122 of layers not containing Si, e.g. PZT, Al2O3
• CPC Class Codes: Y10S 438/924 To facilitate selective etching

Abstract

A system and method for patterning metal oxide materials in a semiconductor structure. The method comprises a first step of depositing a layer of metal oxide material over a substrate. Then, a patterned mask layer is formed over the metal oxide layer leaving one or more first regions of the metal oxide layer exposed. The exposed first regions of the metal oxide layer are then subjected to an energetic particle bombardment process to thereby damage the first regions of the metal oxide layer. The exposed and damaged first regions of the metal oxide layer are then removed by a chemical etch. Advantageously, the system and method is implemented to provide high-k dielectric materials in small-scale semiconductor devices. Besides using the ion implantation damage (I/I damage) plus wet etch technique to metal oxides (including metal oxides not previously etchable by wet methods), other damage methods including lower energy, plasma-based ion bombardment, may be implemented. Plasma-based ion bombardment typically uses simpler and cheaper tooling, and results in less collateral damage to underlying structures as the damage profile can be more easily localized to the depth of the thin metal oxide film.

Claims

1. A method for patterning metal oxide materials in a semiconductor structure comprising the steps of:

a) depositing a layer of metal oxide material over a substrate;

b) forming a patterned mask layer over said metal oxide layer leaving one or more first regions of said metal oxide layer exposed;

c) subjecting said exposed first regions of said metal oxide layer to an energetic particle bombardment process to thereby damage said first regions of said metal oxide layer; and

,

d) removing said exposed and damaged first regions of said metal oxide layer by a chemical etch.

2. The method of claim 1, wherein said energetic particle bombardment process comprises an ion implantation process.

3. The method of claim 2, wherein said ion implantation process is performed with ion implant species selected from the group comprising:

Si, Ge, B, P, Sb, As, O, N. Ar, BF₃.

4. The method of claim 3, wherein said ion implantation process are conducted at ion implant energies ranging from 1 keV to 100 keV.

5. The method of claim 4, wherein the ion implant energies are between 2.0 keV and 10.0 keV.

6. The method of claim 4, wherein the ion implant doses range from between 1×

10¹⁴/cm² to 1×

10⁶/cm².

7. The method of claim 1, wherein said energetic particle bombardment process comprises a charged particle bombardment process.

8. The method of claim 7, wherein said charged particle bombardment process process comprises a plasma treatment in a working gas.

9. The method of claim 1, wherein said energetic particle bombardment comprises exposure to x-rays or photons from pulsed or continuous ultraviolet lasers.

10. The method of claim 8, wherein said working gas includes at least one gas selected from the group comprising:

noble gases including He, Ne, Ar, Kr, Xe, diatomic gases including O₂, N₂, H₂, F₂, Cl₂, Br₂, triatomic gases including CO₂, N₂O, H₂O, halogen containing gases including CF₄, C_xF_y, C_xCl_y, C_xF_yCl_z, and hydrogen-containing gases including C_xH_y, C_xH_yX_z and HX where X=halogen, C_xH_ySi_z, where x,y and z are integers ranging from 1 through 10, and, mixtures including any one of these gases.

11. The method of claim 8, wherein said working gas comprises O₂, Ar, or mixtures thereof.

12. The method of claim 1, wherein said energetic particle bombardment process comprises an ion beam treatment.

13. The method of claim 1, wherein said step of removing said first regions of said metal oxide layer by a chemical etch comprises the step of:

immersing said metal oxide layer in a wet solution having a chemistry selected from the group comprising;

aqueous HF, aqueous buffered HF, and solutions containing at least one of the following components;

inorganic bases such as sodium hydroxide, potassium hydroxide, and ammonium hydroxide;

organic bases such as tetramethyl ammonium hydroxide (TMAH) and choline (2-hydroxyethyltrimethylammonium hydroxide);

hydrogen peroxide;

organic acids such as acetic acid;

HF, sulfuric acid, nitric acid, other mineral acids;

ammonium fluoride, and other buffering salts.

14. The method of claim 1, wherein said metal oxide includes at least 95 wt.-% of the following materials selected from the group of:

metal oxides M-O, metal silicates M-Si—

O, metal aluminates M-Al—

O, metal oxynitrides M-O—

N, metal oxysiliconnitrides M-Si—

N—

O, and metal oxyaluminitrides M-Al—

N—

O, where the metal M is selected from the group including Al, Dy, Er, Eu, Gd, Hf, La, Pr, Sc, Sm, Ta, Te, Th, Ti, Tl, Tm, Y, and Zr, mixtures of metals in this group, and, alloys of metals in this group.

15. The method of claim 1, wherein said metal oxide includes at least 95 wt.-% of HfO₂.

16. The method of claim 1, wherein said metal oxide includes at least 95 wt.-% of ZrO₂.

17. The method of claim 1, wherein said metal oxide includes at least 95 wt.-% of La₂O₃, Al₂O₃, Y₂O₃ or mixtures thereof.

18. The method of claim 1, wherein said metal oxide includes at least 95 wt.-% of of hafnium silicate (Hf—

O—

Si), zirconium silicate (Zr—

O—

Si), or mixtures thereof.

19. The method of claim 1, wherein said metal oxide layer is subjected to a high temperature anneal treatment prior to the step c) of subjecting said exposed first regions of said metal oxide layer to an energetic bombardment process.

20. The method of claim 1, wherein said step of forming a patterned mask layer is performed after said step of subjecting the metal oxide layer to an energetic particle bombardment process.

21. The method of claim 20, wherein said energetic particle bombardment process comprises a nitridation treatment.

22. The method of claim 1, further including the step of removing said patterned mask layer before a final chemical wet etch step.

23. The method of claim 1, further including the step of:

removing said patterned mask layer after a final chemical wet etch step.

24. The method of claim 1, further including repeating steps c) and d) to ensure that a desired thickness of metal oxide film has been removed.

25. A method for providing metal oxide materials in a semiconductor structure comprising the steps of:

a) depositing a film of metal oxide material over a substrate;

b) providing a maskless direct write bombardment process which applies ions or other energetic particle bombardments to selected metal oxide film regions to thereby damage selected regions of said metal oxide film; and

,

c) removing said selected damaged regions of said metal oxide layer by a chemical etch.

26. A method for integrating a dielectric material into a semiconductor device structure comprising the steps of:

a) forming a layer of high-k dielectric material over a semiconductor substrate;

b) forming a patterned mask over said high-k dielectric material layer a region of said high-k layer exposed;

c) subjecting said exposed region of said high-k layer to a energetic particle bombardment process to thereby damage said exposed region of said high-k layer; and

,

d) chemically etching said exposed and damaged regions of said high-k layer.

27. The method of claim 26, wherein said energetic particle bombardment process comprises an ion implantation process.

28. The system for integrating a dielectric material into a semiconductor device structure comprising:

means for forming a layer of high-k dielectric material over a semiconductor substrate;

means for forming a patterned mask over said high-k dielectric material layer to thereby expose a region of said high-k layer;

means for subjecting said exposed region of said high-k layer to an energetic particle bombardment to thereby damage said exposed region of said high-k layer; and

,

means for chemically etching said exposed and damaged regions of said high-k layer.

29. The system as claimed in claim 28, wherein said means for subjecting said exposed region of said high-k layer to an energetic particle bombardment comprises a plasma treatment in a working gas.

30. The system as claimed in claim 29, wherein said plasma treatment is performed in one of:

a conventional reactive ion etch tool, a plasma asher, a high density plasma tool.