Method of making gate structure of a semiconductor device

A method of making a semiconductor device comprising:

• depositing a TiN layer over a substrate;
• doping a first portion of the TiN layer using an oxygen-containing plasma treatment;
• doping a second portion of the TiN layer using a nitrogen-containing plasma treatment, wherein the second portion of the TiN layer directly contacts the first portion of the TiN layer;
• forming a first metal gate electrode over the first portion of the TiN layer, wherein the first metal gate electrode has a variable width in a direction parallel to a top surface of the substrate;
• and
• forming a second metal gate electrode over the second portion of the TiN layer, wherein the second metal gate electrode directly contacts the first metal gate electrode.

A method of making a semiconductor device comprising:

• depositing a TiN layer over a substrate;
• doping a first portion of the TiN layer using an oxygen-containing plasma treatment;
• doping a second portion of the TiN layer using a nitrogen-containing plasma treatment, wherein the second portion of the TiN layer directly contacts the first portion of the TiN layer;
• forming a first metal gate electrode over the first portion of the TiN layer;
• and
• forming a second metal gate electrode over the second portion of the TiN layer, wherein the second metal gate electrode directly contacts the first metal gate electrode, a first sidewall of the second metal gate electrode is substantially perpendicular to a top surface of the substrate, and a second sidewall of the second metal gate electrode is curved.