Method of removing barrier layer

A method for removing a barrier layer of a metal interconnection on a wafer, wherein the method is used in a structure of a process node of 10 nm and below, and the structure comprises a substrate, a dielectric layer, a barrier layer and a metal layer, the dielectric layer is deposited on the substrate and recessed areas are formed on the dielectric layer, the barrier layer is deposited on the dielectric layer, the metal layer is deposited on the barrier layer, wherein the metal layer is a copper layer, the barrier layer is a single-layer metal ruthenium layer, the method comprises the following steps:

• thinning step, being to thin the metal layer, and removing most of the metal layer and leaving a continuous metal layer on the surface of the barrier layer;
• removing step, being to remove the metal layer on the non-recessed areas to expose the barrier layer, leaving the metal layer on the recessed areas with reserved thickness;
• oxidizing step, being to oxidize the single-layer metal ruthenium barrier layer on the non-recessed areas into a ruthenium oxide layer, and meantime remove the retained metal layer on the recessed areas, the oxidizing step using an electrochemical anodic oxidation process;
• and
• oxide layer etching step, being to etch the ruthenium oxide layer on the non-recessed areas with etching liquid to remove the ruthenium oxide layer, so that the recessed areas and the non-recessed areas have a flat surface after etching.

A method for removing a barrier layer of a metal interconnection on a wafer, wherein the method is used in a structure of a process node of 10 nm and below, and the structure comprises a substrate, a dielectric layer, a barrier layer and a metal layer, the dielectric layer is deposited on the substrate and recessed areas are formed on the dielectric layer, the barrier layer is deposited on the dielectric layer, the metal layer is deposited on the barrier layer, wherein the metal layer is a copper layer, the barrier layer is a single-layer metal ruthenium layer, the method comprises the following steps:

• thinning the metal layer to a thickness below 2000 angstroms (Å) by CMP and keeping the metal layer continuous;
• removing the metal layer on the non-recessed areas and oxidizing the single-layer metal ruthenium barrier layer on the non-recessed areas into a ruthenium oxide layer by electrochemical anodic oxidation process;
• and
• etching the ruthenium oxide layer on the non-recessed areas by using etching liquid to remove the ruthenium oxide layer, so that the recessed areas and the non-recessed areas have a flat surface after etching.

A method for removing a barrier layer of a metal interconnection on a wafer, wherein the method is used in a structure of a process node of 10 nm and below, and the structure comprises a substrate, a dielectric layer, a barrier layer and a metal layer, the dielectric layer is deposited on the substrate and recessed areas are formed on the dielectric layer, the barrier layer is deposited on the dielectric layer, the metal layer is deposited on the barrier layer, wherein the metal layer is a copper layer, the barrier layer is a single-layer metal ruthenium layer, the method comprises the following steps:

• removing the entire metal layer on the non-recessed areas by CMP until the barrier layer is exposed;
• oxidizing the single-layer metal ruthenium barrier layer on the non-recessed areas into a ruthenium oxide layer by electrochemical anodic oxidation process;
• and
• etching the ruthenium oxide layer on the non-recessed areas by using etching liquid to remove the ruthenium oxide layer, so that the recessed areas and the non-recessed areas have a flat surface after etching.