Method for Forming Tantalum Nitride Film

• US 20090104775A1
• Filed: 03/03/2006
• Published: 04/23/2009
• Est. Priority Date: 03/03/2005
• Status: Active Grant

• Current Assignee: Ulvac Incorporated
• Original Assignee: Ulvac Incorporated
• Inventors: Nakamura, Kyuzo, Kondo, Tomoyasu, Ushikawa, Harunori, Gonohe, Narishi, Toyoda, Satoru
• Granted Patent: US 8,796,142 B2
• Time in Patent Office: Days
• US Class Current: 438/680
• CPC Class Codes: C23C 16/34 Nitrides C23C16/303 takes precedence
• CPC Class Codes: H01L 21/28556 by chemical means, e.g. CVD, LPCVD, PECVD, laser CVD H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76859 by ion implantation
• CPC Class Codes: H01L 23/53238 Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A tantalum nitride film rich in tantalum atoms is formed, according to the CVD technique, by simultaneously introducing a raw gas consisting of a coordination compound constituted by an elemental tantalum (Ta) having a coordinated ligand represented by the general formula: N=(R, R′) (in the formula, R and R′ may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms) and NH₃ gas into a film-forming chamber, reacting the raw gas with the NH₃ gas and forming a reduced compound having Ta—NH₃ on a substrate; and then introducing a hydrogen atom-containing gas into the chamber to thus form a tantalum nitride film rich in tantalum atoms. The resulting tantalum nitride film has a low resistance, low contents of C and N atoms, and a high compositional ratio: Ta/N, can ensure sufficiently high adherence to Cu film and can thus be useful as a barrier film. Moreover, tantalum particles are implanted in the resulting film according to the sputtering technique to thus further enrich the film with tantalum.

Claims

1. A method for forming a tantalum nitride film comprising the steps, according to the CVD technique, of simultaneously introducing a raw gas consisting of a coordination compound constituted by an elemental tantalum (Ta) having a coordinated ligand represented by the general formula:

N=(R, R′

) (in the formula, R and R′

may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms) and NH₃ gas into a film-forming chamber, reducing the raw gas with the NH₃ gas and forming a reduced compound film on a substrate to thus partially remove the R(R′

) groups bonded to N atoms in the resulting reduced compound film; and

then introducing a hydrogen atom-containing gas into the chamber, and reacting the hydrogen atom-containing gas with the reduced compound film to thus break Ta—

N bonds present in the reduced compound film, to remove the R(R′

) groups, which is bonded to N atom, remaining in the film through cleavage, and to thus form a tantalum nitride film rich in tantalum atoms.

2. The method for forming a tantalum nitride film as set forth in claim 1, wherein the H atom-containing gas is converted into radicals thereof by the action of heat or plasma within the film-forming chamber and the resulting radicals are reacted with the reduced compound film to thus form a tantalum nitride film rich in tantalum atoms.

3. The method for forming a tantalum nitride film as set forth in claim 1, wherein the raw gas is the gas of at least one coordination compound selected from the group consisting of penta-dimethylamino-tantalum, tert-amylimido-tris(dimethylamide) tantalum, penta-diethyl-amino-tantalum, tert-butylimido-tris(dimethylamide) tantalum, tert-butyl-imido-tris(ethyl-methylamide) tantalum, Ta(N(CH₃)₂)₃(NCH₂CH₃)₂ and TaX₅ (X represents a halogen atom).

4. The method for forming a tantalum nitride film as set forth in claim 1, wherein the hydrogen atom-containing gas is at least one gas selected from the group consisting of H₂, NH₃ and SiH₄.

5. The method for forming a tantalum nitride film as set forth in claim 1, wherein the tantalum nitride film is one which satisfies the following requirement:

the compositional ratio of tantalum to nitrogen;

Ta/N≧

2.0.

6. A method for forming a tantalum nitride film comprising the steps of forming a tantalum nitride film according to the method as set forth in claim 1;

and then implanting tantalum particles into the resulting tantalum nitride film according to a sputtering technique which makes use of a target containing tantalum as a principal constituent.

7. The method for forming a tantalum nitride film as set forth in claim 6, wherein the sputtering step is carried out while controlling the DC power and the RF power in such a manner that the DC power is low and the RF power is high.

8. The method for forming a tantalum nitride film as set forth in claim 6, wherein the tantalum nitride film, in which the tantalum particles are implanted, is one which satisfies the following requirement:

the compositional ratio of tantalum to nitrogen;

Ta/N≧

2.0.