Semiconductor device with capping layer and method for fabricating the same
The present application discloses a semiconductor device and a method for fabricating the semiconductor device. The semiconductor device includes a substrate; a capping mask layer positioned on the substrate; a first gate insulating layer positioned along the capping mask layer, inwardly positioned in the substrate, and having a U-shaped cross-sectional profile; a first work function layer positioned on the first gate insulating layer; a first conductive layer positioned on the first work function layer; and a first capping layer positioned on the first conductive layer. The first capping layer comprises germanium oxide. A top surface of the first capping layer and a top surface of the capping mask layer are substantially coplanar.
1 . A method for fabricating a semiconductor device, comprising:
providing a substrate;
forming a capping mask layer on the substrate;
forming a first trench along the capping mask layer and extending to the substrate;
conformally forming a layer of first insulating material into the first trench;
forming a first work function layer on the layer of first insulating material and in the first trench;
forming a first conductive layer on the first work function layer and in the first trench; and
forming a first capping layer on the first conductive layer;
wherein the first capping layer comprises germanium oxide;
wherein the first conductive layer comprises germanium;
wherein the first work function layer comprises silicon and/or germanium with substantially no oxygen and nitrogen;
wherein the first gate insulating layer comprises silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, a high-k material, or a combination thereof;
wherein the capping mask layer comprises silicon oxide, silicon oxycarbide, silicon oxycarbonitride, silicon oxynitride, silicon nitride oxide, or a combination thereof;
wherein forming the first capping layer on the first conductive layer comprises:
alternately and sequentially introducing a germanium precursor and an oxygen source to form a layer of first capping material filling the first trench; and
performing a planarization process until a top surface of the capping mask layer is exposed to turn the layer of first capping material into the first capping layer.
2 . The method for fabricating the semiconductor device of claim 1 , wherein the germanium precursor comprises germanium ethoxide or tetrakis (dimethylamino) germanium.
3 . The method for fabricating the semiconductor device of claim 2 , wherein the oxygen source comprises an activated or excited oxygen species.
4 . The method for fabricating the semiconductor device of claim 3 , wherein a process temperature of forming the first capping layer is between about 20° C. and about 600° C.
5 . The method for fabricating the semiconductor device of claim 4 , wherein the planarization process comprises an etching process, a chemical mechanical polishing process, or a combination thereof.