Method for preparing metal nitride thin films

• US 20020182320A1
• Filed: 03/15/2002
• Published: 12/05/2002
• Est. Priority Date: 03/16/2001
• Status: Active Grant

• Current Assignee: ASM International NV
• Original Assignee: ASM International NV
• Inventors: Ritala, Mikko, Leskela, Markku, Alen, Petra, Juppo, Marika
• Granted Patent: US 6,706,115 B2
• Time in Patent Office: Days
• US Class Current: 427/250
• CPC Class Codes: C23C 16/34 Nitrides C23C16/303 takes precedence
• CPC Class Codes: C23C 16/45553 characterized by the use of precursors specially adapted for ALD
• CPC Class Codes: H01L 21/28568 the conductive layers comprising transition metals H01L21/28518 takes precedence

Abstract

An object of the invention is to produce metal nitride thin layers having low resistivity by means of the ALD method. In the method according to the invention, compounds that are bbetter reducing properties than the known ammonia and 1,1-dimethyl hydrazine are used as nitrogen source. Suitable compounds for that purpose are those in which a hydrocarbon group bound to nitrogen, when dissociating in a homolytic manner, generates a radical that serves as a reducing agent and reacts further to generate atomic hydrogen. The nitride thin layers produced according to the invention are especially suitable for use as diffusion barrier layers in integrated circuits.

Claims

1. A method of growing transition metal nitride thin films in accordance with the principles of the ALD method, according to which method a nitride thin film is grown on a substrate by means of alternate surface reactions of metal and nitrogen source materials, characterized by using as nitrogen source material a compound having a hydrocarbon, amino or silyl group bound to nitrogen, which group, when it dissociates in a homolytic manner from nitrogen, generates a radical which serves as a reducing agent and/or reacts further to generate atomic hydrogen.

2. The method according to claim 1, characterized by using as the nitrogen source material one or more compounds of formula (I)

NR_xH_3-x 

 

(I)

wherein

R is a hydrocarbon, amino or silyl group, each R can be the same or different, and

x is an integer 1, 2 or 3.

3. The method according to any of the preceding claims, characterized in that the bond energy between amine and the hydrocarbon group R is less than 460 kJ/mol.

4. The method according to claim 1 or claim 2, characterized in that R is a substituted or unsubstituted, cyclic, linear or branched, an alkyl, alkenyl, allyl, aryl, alkylaryl, or arylalkyl group.

5. The method according to any of the preceding claims, characterized in that R is a linear or branched C₁-C₁₀ alkyl, preferably a tertiary alkyl.

6. The method according to any of the preceding claims, characterized in that one or more said nitrogen source material is used together with ammonia, hydrazine or hydrazine derivatives.

7. The method according to any of the preceding claims, characterized by using as the metal source material a compound of formula (II)

MX_nL_z 

 

(II)

wherein

M is a transition metal,

X is a negatively charged ligand;

each X is independently a halide, hydride, alkylamide, alkoxide, aryloxide, alkyl, cyclopentadienyl or β

-diketonate,

n is an integer indicating the number of ligands X, when each ligand has a charge of −

1, n is the same as the oxidation state of metal in the source material MX_n,

L is a neutral adduct ligand binding to M at one or more of its atoms, and

z is an integer 0, 1, 2, 3 or 4.

8. The method according to claim 7, characterized in that the metal M belongs to the group 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 of the periodic table according to the numbering of groups recommended by IUPAC.

9. The method according to claim 7 or 8, characterized in that the metal source material is a halide or alkylamide of a transition metal.

10. The method according to any of the preceding claims, characterized in that the metal source material is TaCl₅, TaBr₅, or Tal₅, and at least tert-butylamine or allylamine is used as the nitrogen source material.

11. The method according to any of the preceding claims, characterized in that the metal source material is TiCl₄, TiBr₄ of TiI₄, and at least tert-butylamine or allylamine is used as the nitrogen source material.

14. A method according to claim 13 for producing a conductive TaN diffusion barrier layer, characterized in that the tantalum source material is selected from one or more compounds of the group of tantalum pentachloride, tantalum pentaiodide and tantalum pentabromide, and the nitrogen source is selected from tert-butyl amine or allyl amine, or tert-butyl amine or allylamide together with ammonia.

12. A method of producing an electrically conductive diffusion barrier layer on a substrate comprising integrated circuits between a conductor and an isolation layer, according to which method

the integrated circuit comprising conductors is introduced into the reaction space of an ALD reactor, and

a conductive metal nitride thin layer is grown on the integrated circuit in accordance with the principles of the ALD method by means of alternate surface reactions of the metal and nitrogen source materials,

characterized in that

the nitrogen source is selected from a compound having such a hydrocarbon, amino or silyl group attached to the nitrogen that when dissociating in a homolytic manner from the nitrogen, it generates a radical that serves as a reducing agent and/or reacts further and generates atomic hydrogen.

13. A method of producing a conductive TaN diffusion barrier layer on a substrate comprised of integrated circuits, according to which method

an integrated circuit comprising conductors is introduced into the reaction space of an ALD reactor, and

a conductive metal nitride thin layer is grown on the integrated circuit in accordance with the principles of the ALD method by means of alternate surface reactions of the tantalum and nitrogen source materials,

characterized in that

the nitrogen source is selected from a compound having such a hydrocarbon, amino or silyl group attached to the nitrogen that when dissociating in a homolytic manner from the nitrogen, it generates a radical that serves as a reducing agent and/or reacts further and generates atomic hydrogen.