Alternative gate dielectric films for silicon germanium and germanium channel materials
Embodiments of the present invention provide a high-K dielectric film for use with silicon germanium (SiGe) or germanium channel materials, and methods of fabrication. As a first step of this process, an interfacial layer (IL) is formed on the semiconductor substrate providing reduced interface trap density. However, an ultra-thin layer is used as a barrier film to avoid germanium diffusion in high-k film and oxygen diffusion from the high-k film to the interfacial layer (IL), therefore, dielectric films such as aluminum oxide (Al 2 O 3 ), zirconium oxide, or lanthanum oxide (La 2 O 3 ) may be used. In addition, these films can provide high thermal budget. A second dielectric layer is then deposited on the first dielectric layer. The second dielectric layer is a high-k dielectric layer, providing a reduced effective oxide thickness (EOT), resulting in improved device performance.
1. A method of forming a semiconductor structure, the method comprising:
performing a surface oxidation of a semiconductor substrate to form an interfacial oxide layer;
depositing a first dielectric layer on the interfacial oxide layer;
performing a densifying process to densify the surface oxidation of said first dielectric layer; and
depositing a second dielectric layer on the first dielectric layer.
2. The method of claim 1 , wherein performing a surface oxidation comprises performing a remote plasma oxidation process.
3. The method of claim 1 , wherein forming an interfacial oxide layer comprises forming an interfacial oxide layer having a thickness ranging from about 2 angstroms to about 5 angstroms.
4. The method of claim 2 , wherein performing a surface oxidation of a semiconductor substrate comprises performing a surface oxidation of a silicon germanium substrate.
5. The method of claim 1 , wherein depositing a first dielectric layer is performed using an atomic layer deposition process.
6. The method of claim 1 , wherein depositing a first dielectric layer comprises depositing aluminum oxide.
7. The method of claim 1 , wherein depositing a first dielectric layer comprises depositing silicon nitride.
8. The method of claim 1 , further comprising performing a plasma ozone oxidation process.
9. The method of claim 1 wherein depositing a second dielectric layer comprises depositing titanium oxide.
10. The method of claim 1 wherein depositing a second dielectric layer comprises depositing hafnium oxide.
11. The method of claim 1 wherein depositing a second dielectric layer comprises depositing zirconium oxide.
12. The method of claim 1 wherein depositing a second dielectric layer comprises depositing lanthanum oxide.
13. A method of forming a semiconductor structure, the method comprising:
performing a surface oxidation process upon a semiconductor substrate to form an interfacial oxide layer, wherein said interfacial oxide layer having a thickness ranging from about 2 angstroms to about 5 angstroms;
depositing a first dielectric layer on the interfacial oxide layer; and
depositing a second dielectric layer on the first dielectric layer.
14. The method of claim 13 , wherein said surface oxidation process upon comprises performing a remote plasma oxidation process upon a silicon germanium substrate.
15. The method of claim 13 , wherein depositing said first dielectric layer is performed using an atomic layer deposition process.
16. The method of claim 13 , wherein depositing said first dielectric layer comprises depositing at least one of:
depositing silicon nitride; or
depositing aluminum oxide.
17. The method of claim 13 , further comprising performing a plasma ozone oxidation process.
18. The method of claim 13 wherein depositing said second dielectric layer comprises at least one of:
depositing titanium oxide;
depositing hafnium oxide;
depositing zirconium oxide; or
depositing lanthanum oxide.
19. The method of claim 13 , wherein performing said surface oxidation comprises performing a remote plasma oxidation process.
20. The method of claim 13 , further comprising performing a densifying process to densify the surface of said first dielectric layer.