Semiconductor device having barrier layer to prevent impurity diffusion

A semiconductor device comprising:

• a semiconductor substrate having a first conductivity type region including a first conductivity type impurity;
• a first gate structure on the semiconductor substrate overlying the first conductivity type region;
• a second gate structure on the semiconductor substrate overlying the first conductivity type region and adjacent the first gate structure;
• source and drain regions having including a second conductivity type impurity formed in the semiconductor substrate between the first gate structure and the second gate structure,
• wherein the source and drain regions are separated by a shallow trench isolation region;
• and
• a barrier layer located between the substrate and the source and drain regions,
• wherein the barrier layer prevents diffusion of the second conductivity type impurity from the source and drain regions into the substrate, and
• wherein the barrier layer is in direct contact with the source and drain regions.

A semiconductor device comprising:

• a semiconductor substrate having a first conductivity type region including a first conductivity type impurity;
• a first gate structure on the semiconductor substrate overlying the first conductivity type region;
• a second gate structure on the semiconductor substrate overlying the first conductivity type region and adjacent the first gate structure;
• a second conductivity type region including a second conductivity type impurity formed in the semiconductor substrate between the first gate structure and the second gate structure;
• and
• a barrier layer located between the first conductivity type region and the second conductivity type region, wherein the barrier layer prevents diffusion of the second conductivity type impurity from the second conductivity type region into the first conductivity type region,
• wherein the second conductivity type region includes a first portion and a second portion, wherein the second portion contains a higher concentration of the second conductivity type impurity than the first portion, and
• wherein the first portion and the second portion are in direct contact with each other.