Semiconductor device with programmable element and method for fabricating the same

1. A semiconductor device, comprising:

a substrate;

a channel region positioned in the substrate;

first impurity regions positioned in the substrate and respectively positioned on two ends of the channel region;

a gate dielectric layer positioned on the channel region;

a gate bottom conductive layer positioned on the gate dielectric layer;

a plurality of composite contacts respectively positioned on the first impurity regions, wherein at least one of the plurality of composite contacts includes a protection liner having a U-shaped profile and a metal core in the protection liner;

programmable insulating layers respectively positioned on the composite contacts;

a top conductive layer positioned on the programmable insulating layers and electrically coupled to the gate bottom conductive layer, wherein thicknesses of the programmable insulating layers are different from a thickness of the gate dielectric layer; and

a gate top conductive layer positioned on the gate bottom conductive layer and electrically coupled to the top conductive layer, wherein the gate top conductive layer is formed of titanium silicide, nickel silicide, nickel platinum silicide, tantalum silicide, or cobalt silicide;

wherein a thickness of the gate top conductive layer is between about 2 nm and about 20 nm.

2. The semiconductor device of claim 1 , further comprising first gate spacers positioned on sidewalls of the gate dielectric layer and sidewalls of the gate bottom conductive layer.

3. The semiconductor device of claim 2 , further comprising second gate spacers positioned on sidewalls of the first gate spacers.

4. The semiconductor device of claim 2 , further comprising a peak portion having a triangular cross-sectional profile and positioned between the channel region and the gate dielectric layer, wherein the gate dielectric layer comprises a capping portion positioned on the peak portion and flat portions respectively connecting to two ends of the capping portion and positioned on the channel region.

5. The semiconductor device of claim 4 , wherein a thickness of the capping portion is equal to or less than thicknesses of the flat portions.

6. The semiconductor device of claim 5 , wherein the peak portion comprises a first faceted plane and a second faceted plane both contacting the capping portion and an angle between the first faceted plane and the second faceted plane is between about 50 degrees and about 60 degrees.

7. The semiconductor device of claim 2 , further comprising a composite gate via positioned between the top conductive layer and the gate top conductive layer, wherein the top conductive layer and the gate top conductive layer are electrically coupled through the composite gate via, and the composite gate via includes a protection liner having a U-shaped profile and a metal gate via in the protection liner.

8. The semiconductor device of claim 7 , further comprising a covering layer covering the first impurity regions, the first gate spacers, and the gate top conductive layer, wherein the composite contacts are respectively positioned along the covering layer and respectively positioned on the first impurity regions and the composite gate via is positioned along the covering layer and positioned on the gate top conductive layer.

9. The semiconductor device of claim 2 , further comprising a second impurity region positioned in the substrate and distant from the first impurity regions, wherein the second impurity region has a different electrical type from the first impurity regions and one of the composite contacts is electrically coupled to the second impurity region.