US Patent 7928498 Gate structures in semiconductor devices

A gate structure includes an insulation layer on a substrate, a first conductive layer pattern on the insulation layer, a metal ohmic layer pattern on the first conductive layer pattern, a diffusion preventing layer pattern on the metal ohmic layer pattern, an amorphous layer pattern on the diffusion preventing layer pattern, and a second conductive layer pattern on the amorphous layer pattern. The gate structure may have a low sheet resistance and desired thermal stability.