Method for forming a field effect transistor having a high-k gate dielectric
View Patent ↗According to one exemplary embodiment, a method for forming a field effect transistor over a substrate comprises a step of forming an interfacial oxide layer over a channel region of the substrate, where the interfacial oxide layer has a first thickness. The interfacial oxide layer can prevent a high-k element from diffusing into the channel region. The method further comprises forming an oxygen-attracting layer over the interfacial oxide layer, where the oxygen-attracting layer prevents the first thickness of the interfacial oxide layer from increasing. The oxygen-attracting layer is formed by forming a metal layer over the interfacial oxide layer, where the metal layer combines with oxygen to form a silicate. The oxygen-attracting layer may be zirconium silicate or hafnium silicate, for example. The method further comprises forming a high-k dielectric layer over the oxygen-attracting layer. The method further comprises forming a gate electrode layer over the high-k dielectric layer.
1. A method for forming a field effect transistor over a substrate, said method comprising steps of:
forming a high-k dielectric layer over a channel region of said substrate;
forming an oxygen-attracting layer over said high-k dielectric layer;
forming a gate electrode layer over said oxygen-attracting layer;
wherein said oxygen-attracting layer prevents an interfacial oxide layer from forming between said high-k dielectric layer and said substrate.
2. The method of claim 1 wherein said step of forming said oxygen-attracting layer comprises forming a metal layer over said high-k dielectric layer, said metal layer combining with oxygen from said high-k dielectric layer to form a high-k dielectric.
3. The method of claim 1 wherein said oxygen-attracting layer and said high-k dielectric layer form a high-k gate dielectric stack.
4. The method of claim 1 wherein said oxygen-attracting layer is selected from the group consisting of zirconium oxide and hafnium oxide.
5. The method of claim 1 wherein said high-k dielectric layer is selected from the group consisting of zirconium oxide and hafnium oxide.
6. The method of claim 1 wherein said oxygen-attracting layer has a thickness of approximately 5.0 Angstroms.
7. The method of claim 1 wherein said high-k dielectric layer has a thickness of between approximately 20.0 Angstroms and approximately 30.0 Angstroms.