Method of manufacturing a semiconductor device using a metal oxide film
To allow a metal oxide film composed mainly of O and at least one of Hf and Zr to exhibit ferroelectric properties. After deposition of a hafnium oxide film on a semiconductor substrate via an insulating film, the semiconductor substrate is exposed to microwaves to selectively heat the hafnium oxide film. This makes it possible to form a larger number of orthorhombic crystals in the crystals of the hafnium oxide film. The hafnium oxide film thus obtained can therefore exhibit ferroelectric properties without adding, thereto, an impurity such as Si. This means that the hafnium oxide film having a reverse size effect can be used as a ferroelectric film of a ferroelectric memory cell and contributes to the manufacture of a miniaturized ferroelectric memory cell.
1. A method of manufacturing a semiconductor device, comprising:
(a) depositing a metal oxide film having oxygen and at least one of hafnium and zirconium as a main component on a semiconductor substrate;
(b) depositing a conductor film on the metal oxide film;
(c) subjecting the metal oxide film to microwave heat treatment;
(d) depositing a semiconductor film on the conductor film; and
(e) patterning a semiconductor film, the conductor film and the metal oxide film to form a gate electrode and a ferroelectric film;
wherein the gate electrode and the ferroelectric film configure a ferroelectric memory cell.
2. The method of manufacturing a semiconductor device according to claim 1 ,
wherein (c) is performed after (a) and before (b).
3. The method of manufacturing a semiconductor device according to claim 1 ,
wherein (c) is performed after (b).
4. The method of manufacturing a semiconductor device according to claim 1 ,
wherein (a) comprises:
(a1) forming a first insulating film over the semiconductor substrate; and
(a2) depositing the metal oxide film to cover the first insulating film therewith.
5. The method of manufacturing a semiconductor device according to claim 1 ,
wherein (a) comprises:
(a1) forming a protrusion which has a portion of the semiconductor substrate and protrudes from the main surface of the semiconductor substrate; and
(a2) depositing the metal oxide film over the main surface of the semiconductor substrate to cover the protrusion.
6. The method of manufacturing a semiconductor device according to claim 5 , comprising, after (a1) and before (a2):
forming a second insulating film over the surface of the protrusion.
7. The method of manufacturing a semiconductor device according to claim 1 ,
wherein the conductor film in (b) has titanium nitride as a main component.
8. The method of manufacturing a semiconductor device according to claim 7 ,
wherein the conductor film is deposited by RF sputtering.
9. The method of manufacturing a semiconductor device according to claim 1 ,
wherein at least any one of elements silicon, nitrogen, carbon and fluorine is added to the metal oxide film.
10. The method of manufacturing a semiconductor device according to claim 1 ,
wherein the frequency of the microwaves in (c) is from 1 GHz to 10 GHz.
11. The method of manufacturing a semiconductor device according to claim 1 ,
wherein the gate electrode is formed of the semiconductor film and the conductor film, and
wherein the ferroelectric film is formed of the metal oxide film.
12. The method of manufacturing a semiconductor device according to claim 1 , comprising:
(f) forming a source region and a drain region in the semiconductor substrate exposed from the ferroelectric film,
wherein the gate electrode, the ferroelectric film, the source region and the drain region configure the ferroelectric memory cell.