Semiconductor device with ferroelectric hafnium oxide and method for forming semiconductor device
The present disclosure provides a semiconductor device comprising a substrate, an undoped HfO 2 layer formed over the substrate and a TiN layer formed on the HfO 2 layer. Herein, the undoped HfO 2 layer is at least partially ferroelectric. In illustrative methods for forming a semiconductor device, an undoped amorphous HfO 2 layer is formed over a semiconductor substrate and a TiN layer is formed on the undoped amorphous HfO 2 layer. A thermal annealing process is performed for at least partially inducing a ferroelectric phase in the undoped amorphous HfO 2 layer.
1. A semiconductor device, comprising:
a substrate;
an undoped HfO 2 layer formed over said substrate, wherein said undoped HfO 2 layer is at least partially ferroelectric; and
a TiN layer formed on said undoped HfO 2 layer, wherein said TiN layer has an oxygen content profile formed therein, said oxygen content profile showing an oxygen content at an upper surface of said TiN layer in a range from about 5-15% and an oxygen content at an interface of said TiN layer with said undoped HfO 2 layer in a range from about 0-7%.
2. The semiconductor device of claim 1 , wherein said oxygen content profile represents an oxygen gradient.
3. The semiconductor device of claim 1 , wherein said undoped HfO 2 layer has a thickness in a range from about 1-30 nm.
4. The semiconductor device of claim 1 , wherein said undoped HfO 2 layer has a thickness in a range from about 2-20 nm.
5. The semiconductor device of claim 1 , wherein said TiN layer has a bulk resistivity in a range from about 100-400 μΩcm.
6. The semiconductor device of claim 1 , wherein said TiN layer has a bulk resistivity in a range from about 100-300 μΩcm.
7. The semiconductor device of claim 1 , wherein said TiN layer has a density in a range from about 4.5-5.2 g/cm 3 .
8. The semiconductor device of claim 1 , further comprising a gate material layer formed above said undoped HfO2 layer and said TiN layer.
9. The semiconductor device of claim 8 , wherein said undoped HfO 2 layer is formed on an SiON layer.
10. The semiconductor device of claim 1 , further comprising a bottom electrode layer formed below said undoped HfO 2 layer and said TiN layer.
11. A method for forming a semiconductor device, comprising:
forming an undoped amorphous HfO 2 layer over a semiconductor substrate;
forming a TiN layer on said undoped amorphous HfO 2 layer, wherein said TiN layer has an oxygen content profile formed therein, said oxygen content profile showing an oxygen content at an upper surface of said TiN layer in a range from about 5-15% and an oxygen content at an interface of said TiN layer with said undoped HfO 2 layer in a range from about 0-7%; and
performing a thermal annealing process for at least partially inducing a ferroelectric phase in said undoped amorphous HfO 2 layer.
12. The method of claim 11 , wherein said TiN layer is deposited by performing a PVD process in an atmosphere comprising one of nitrogen and oxygen/nitrogen.
13. The method of claim 12 , wherein said PVD process is performed at temperatures smaller or equal than about 400° C.
14. The method of claim 13 , further comprising adjusting a specific ratio of titanium/nitrogen when performing said PVD process.
15. The method of claim 11 , wherein said TiN layer is amorphous.
16. The method of claim 11 , wherein said undoped amorphous HfO 2 layer is formed by performing an ALD process to deposit a layer of undoped amorphous HfO 2 with a thickness in a range from 4-20 nm.
17. The method of claim 16 , wherein a deposition temperature during said ALD process is out of a range from about 200-400° C.
18. The method of claim 11 , wherein said thermal annealing process is performed at an annealing temperature of at least about 400° C. and at most about 1100° C.