Semiconductor device and manufacturing method for the same

A method for fabricating a semiconductor structure, comprising:

• forming a dielectric layer over a first region and a second region of a substrate, wherein the second region is adjacent to the first region, and a profile of the dielectric layer presents a plurality of recesses extending toward the substrate;
• forming a high-k material over the dielectric layer in the first region and the second region;
• patterning a first oxygen capturing layer with a mask to expose a portion of the high-k material in the second region;
• applying oxidizing agent over the first oxygen capturing layer, wherein a first thickness of the dielectric layer in the first region becomes greater than a second thickness of the dielectric layer in the second region subsequent to applying the oxidizing agent;
• removing a remaining portion of the first oxygen capturing layer after applying oxidizing agent over the first oxygen capturing layer to expose the recess in the first region;
• and
• forming a gate structure in the exposed recess in the first region.

A method for fabricating a semiconductor structure, comprising:

• forming a first gate structure over a first region of a substrate and forming a second gate structure over a second region adjacent to the first region, comprising;
• forming a dielectric layer over the first region and the second region;
• forming a high-k material covering the dielectric layer in the first region and the second region;
• forming an oxygen capturing layer covering the high-k material in the first region;
• increasing a concentration of oxygen in the oxygen capturing layer by applying oxidizing agent over a top surface of the oxygen capturing layer under a first temperature;
• performing an annealing operation on the oxygen capturing layer under a second temperature, wherein the first temperature is lower than the second temperature;
• removing the oxygen capturing layer from the first region after the annealing operation;
• and
• forming a work function metal layer over the high-k material,
• wherein a first thickness of the dielectric layer in the first region becomes greater than a second thickness of the dielectric layer in the second region subsequent to applying the oxidizing agent.