Method of forming high voltage transistor and structure resulting therefrom

A semiconductor structure, comprising:

• a substrate;
• a first dielectric layer over the substrate;
• a second dielectric layer over the first dielectric layer;
• a third dielectric layer within the second dielectric layer, wherein the second dielectric layer comprises an element with a first concentration in the third dielectric layer greater than a second concentration of the element in other portions of the second dielectric layer;
• and
• a first gate electrode over the first dielectric layer and the second dielectric layer.

A semiconductor structure, comprising:

• a barrier layer in a substrate;
• a gate dielectric layer over the substrate, the gate dielectric layer comprising a first portion and a second portion, wherein the first portion is thicker than the second portion, wherein the first portion comprises a first material and a second material different from the first material and wrapped around by the first material;
• a gate electrode over the gate dielectric layer;
• and
• a gate spacer on two sides of the gate electrode.