Semiconductor device including work function layer doped with barrier elements and method for forming the same

A method of manufacturing a semiconductor device, comprising:

• forming a transistor region in a substrate;
• forming a gate dielectric layer over the transistor region;
• forming a diffusion-blocking layer over the gate dielectric layer;
• forming a work function layer over the diffusion-blocking layer;
• depositing an oxygen-trapping element on or under a top surface of the work function layer;
• forming an oxide layer from the oxygen-trapping element trapping oxygen from an ambient environment;
• removing the oxide layer;
• and
• forming a gate electrode over the work function layer, wherein
• the oxygen-trapping element is formed by fractionally and sequentially injecting a precursor compound of the oxygen-trapping element into an ALD chamber, and
• a duration of the precursor compound of the oxygen-trapping element injected into the ALD chamber is increased in an interval.

A method of manufacturing a semiconductor device, comprising:

• forming a transistor region in a substrate;
• forming a gate dielectric layer over the transistor region;
• forming a diffusion-blocking layer over the gate dielectric layer;
• forming a first portion of a work function layer over the diffusion-blocking layer;
• simultaneously forming a second portion of the work function layer and an oxygen-trapping element on a top surface of the first portion of the work function layer;
• forming an oxide layer from the oxygen-trapping element trapping oxygen from an ambient environment;
• removing the oxide layer by reacting the oxide layer with a metal halide compound;
• and
• forming a gate electrode over the second portion of the work function layer, wherein
• the oxygen-trapping element is formed by fractionally and sequentially injecting a precursor compound of the oxygen-trapping element into an ALD chamber, and
• a duration of the precursor compound of the oxygen-trapping element injected into the ALD chamber is increased in an interval.