Electroless plating process, and embedded wire and forming process thereof

• US 20030068887A1
• Filed: 09/04/2002
• Published: 04/10/2003
• Est. Priority Date: 10/05/2001
• Status: Active Grant

• Current Assignee: Semiconductor Technology Academic Research Center
• Original Assignee: Semiconductor Technology Academic Research Center
• Inventors: Sakaue, Hiroyuki, Takahagi, Takayuki, Shingubara, Shoso
• Granted Patent: US 6,852,624 B2
• Time in Patent Office: Days
• US Class Current: 438/687
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76856 by treatment in plasmas or gaseous environments, e.g. nitriding a refractory metal liner
• CPC Class Codes: H01L 21/76873 for electroplating
• CPC Class Codes: H01L 21/76874 for electroless plating
• CPC Class Codes: H01L 2221/1089 Stacks of seed layers

Abstract

The present invention is to provide a process for forming the embedded wires having the higher density and the finer pitch without using catalyzing agent in an economical manner. The electroless plating process of copper according to the present invention includes steps of preparing a substrate, and forming a metal nitride layer containing high melting-point metal on the substrate. The metal nitride layer has a stabilized nitride layer in the vicinity of a top surface thereof. The stabilized nitride layer has a composition ratio of nitrogen atoms over oxygen atoms, which is about 0.4 or more. The process also includes a step of immersing the substrate into a plating solution containing copper so as to displace high melting-point metal contained in the metal nitride layer by copper, thereby forming an electroless copper plating layer on the metal nitride layer.

Claims

1. An electroless plating process of copper, comprising steps of:

preparing a substrate;

forming a metal nitride layer containing high melting-point metal on the substrate, the metal nitride layer having a stabilized nitride layer in the vicinity of a top surface thereof, the stabilized nitride layer having a composition ratio of nitrogen atoms over oxygen atoms, which is about 0.4 or more;

immersing the substrate into a plating solution containing copper so as to displace high melting-point metal contained in the metal nitride layer by copper, thereby forming an electroless copper plating layer on the metal nitride layer.

2. The process according to claim 1,

wherein the stabilized nitride layer has a depth of approximately 5 nm.

3. The process according to claim 1,

wherein the stabilized nitride layer is formed by applying nitrogen plasma on the top surface of the metal nitride layer formed on the substrate.

4. The process according to claim 1,

wherein the stabilized nitride layer is formed by removing the top surface of the metal nitride layer formed on the substrate.

5. The process according to claim 1,

wherein the stabilized nitride layer is formed by depositing the metal nitride layer substantially having the stoichiometrical composition.

6. An electroless plating process of copper, comprising steps of:

preparing a substrate;

forming a metal layer on the substrate, the metal layer mainly made of high melting-point metal selected from a group consisting of titanium, cobalt, and alloy thereof;

immersing the substrate into a plating solution containing copper so as to displace high melting-point metal by copper, thereby forming an electroless copper plating layer on the metal nitride layer.

7. A process for forming an embedded wire of copper, comprising steps of:

preparing a substrate;

forming a pit on the substrate;

forming a barrier metal layer containing high melting-point metal on the substrate, the barrier metal layer having a stabilized nitride layer in the vicinity of a top surface thereof, the stabilized nitride layer having a composition ratio of nitrogen atoms over oxygen atoms, which is about 0.4 or more;

immersing the substrate into a plating solution containing copper so as to displace high melting-point metal contained in the barrier metal layer by copper, thereby forming an electroless copper plating layer on the metal nitride layer.

8. The process according to claim 7,

wherein the stabilized nitride layer is formed by applying nitrogen plasma on the top surface of the metal nitride layer formed on the substrate.

9. The process according to claim 7, further comprising a step of:

forming an electroplating layer of copper on the electroless plating layer using as a seed layer.

10. An embedded wire of copper, comprising:

a substrate;

a pit formed on said substrate;

a barrier metal layer of metal nitride containing high melting-point metal formed on an inner side wall of said pit;

a copper plating layer formed on said barrier metal layer, filling the pit up with copper metal; and

a stabilized nitride layer at an interface between said barrier metal layer and said copper plating layer;

wherein said stabilized nitride layer has a composition ratio of the number of nitrogen atoms over the number of oxygen atoms contained therein, which is about 0.4 or more.

11. The embedded wire according to claim 10,

wherein said stabilized nitride layer has a thickness of approximately 5 nm.