Hybrid bonding mechanisms for semiconductor wafers

A method of forming a hybrid bonding structure, the method comprising:

• depositing an etch stop layer over a substrate, wherein the substrate comprises a conductive structure;
• depositing a dielectric material over the etch stop layer;
• forming an opening in the dielectric material, wherein the opening exposes the conductive structure;
• depositing a first barrier layer to line the opening;
• etching a first portion of the first barrier layer outside the opening and at a bottom surface of the opening, wherein the etching exposes the conductive structure and removes the first barrier layer from over a top surface of the dielectric material, wherein a second portion of the first barrier layer covers sidewalls of the opening and has a tapered corner after the etching;
• wherein the tapered corner after the etching extends from a top surface of a planarization stop layer deposited over the dielectric material to a point coplanar with a bottom surface of the planarization stop layer;
• depositing a second barrier layer, wherein the second barrier layer covers exposed surfaces of the second portion of the first barrier layer and covers the tapered corner of the first barrier layer;
• depositing a conductive material to fill space in the opening;
• and
• removing the conductive material and the second barrier layer outside the opening to form a conductive pad with the first barrier layer surrounding the second barrier layer and the conductive pad.

A method of forming a hybrid bonding structure, the method comprising:

• depositing an etch stop layer over a substrate, wherein the substrate comprises a conductive structure having a top surface;
• depositing a dielectric material and a planarization stop layer over the etch stop layer;
• forming an opening in the dielectric material, wherein the opening exposes the top surface of the conductive structure;
• depositing an underlying barrier layer in the opening;
• etching the underlying barrier layer to remove the underlying barrier layer from a bottom surface of the opening and to provide a tapered corner of the underlying barrier layer, wherein the tapered corner extends from a top surface of the planarization stop layer to a point in the opening coplanar with a bottom surface of the planarization stop layer;
• depositing another barrier layer to line the opening, wherein the another barrier layer forms an interface with the top surface of the conductive structure;
• filling the opening with a conductive material, wherein the conductive material is disposed over the interface of the another barrier layer and the top surface of the conductive structure;
• and
• removing the conductive material outside the opening, wherein removing the conductive material outside the opening comprises defining a top surface of the conductive material above a top surface of the dielectric material.