Abstract: A semiconductor device, including a first MOS device, a second MOS device, a first dielectric layer, a stop layer, and a second dielectric layer, is provided. The first MOS device and the second MOS device are located on a substrate. The first dielectric layer is beside the first MOS device and the second MOS device. The stop layer is disposed on the first dielectric layer. The second dielectric layer covers the stop layer. The thickness of the second dielectric layer above the first MOS device is greater than the thickness of the second dielectric layer above the second MOS device.

Abstract: A semiconductor structure includes a substrate and a buried gate structure in the substrate. The buried gate structure includes a gate dielectric layer formed on the sidewall and the bottom surface of a trench in the substrate, a barrier layer formed in the trench and on the sidewall and the bottom surface of the gate dielectric layer, a first work function layer formed in the trench and including a main portion and a protruding portion, a second work function layer formed at opposite sides of the protruding portion, and an insulating layer formed in the trench and on the protruding portion of the first work function layer and the second work function layer. The barrier layer surrounds the main portion of the first work function layer. The area of the top surface of the protruding portion is less than the area of the bottom surface of the protruding portion.

Abstract: A semiconductor structure includes a substrate and a buried gate structure in the substrate. The buried gate structure includes a gate dielectric layer formed on the sidewall and the bottom surface of a trench in the substrate, a barrier layer formed in the trench and on the sidewall and the bottom surface of the gate dielectric layer, a first work function layer formed in the trench and including a main portion and a protruding portion, a second work function layer formed at opposite sides of the protruding portion, and an insulating layer formed in the trench and on the protruding portion of the first work function layer and the second work function layer. The barrier layer surrounds the main portion of the first work function layer. The area of the top surface of the protruding portion is less than the area of the bottom surface of the protruding portion.

Abstract: A semiconductor structure includes a substrate and a buried gate structure in the substrate. The buried gate structure includes a gate dielectric layer formed on the sidewall and the bottom surface of a trench in the substrate, a barrier layer formed in the trench and on the sidewall and the bottom surface of the gate dielectric layer, a first work function layer formed in the trench and including a main portion and a protruding portion, a second work function layer formed at opposite sides of the protruding portion, and an insulating layer formed in the trench and on the protruding portion of the first work function layer and the second work function layer. The barrier layer surrounds the main portion of the first work function layer. The area of the top surface of the protruding portion is less than the area of the bottom surface of the protruding portion.