Ferroelectric stacked-layer structure, field effect transistor, and ferroelectric capacitor and fabrication methods thereof
OwnerHiroyuki TANAKA, Yoshihisa Kato +1inventors
InventorsHiroyuki TANAKA, Yoshihisa Kato, Yukihiro Kaneko
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Abstract
A ferroelectric stacked-layer structure is fabricated by forming a first polycrystalline ferroelectric film on a polycrystalline or amorphous substrate, and after planarizing a surface of the first ferroelectric film, laminating on the first ferroelectric film a second thin ferroelectric film having the same crystalline structure as the first ferroelectric film. A field effect transistor or a ferroelectric capacitor includes the ferroelectric stacked-layer structure as a gate insulating film or a capacitor film.
Claims24
A method for fabricating a ferroelectric stacked-layer structure, comprising:
- (a) forming a first polycrystalline ferroelectric film on a polycrystalline or amorphous substrate;
- (b) planarizing a surface of the first ferroelectric film;
- (c) stacking on the planarized first ferroelectric film a second thin ferroelectric film having the same crystalline structure as the first ferroelectric film.
A ferroelectric stacked-layer structure formed on a polycrystalline or amorphous substrate, comprising:
- a first polycrystalline ferroelectric film;
- and
- a second thin ferroelectric film stacked on the first ferroelectric film,
- wherein the first ferroelectric film has a planarized surface, and
- the second ferroelectric film has the same crystalline structure as the first ferroelectric film.
A method for fabricating a field effect transistor, comprising:
- (a) forming a gate electrode on a substrate;
- (b) forming a first polycrystalline ferroelectric film on the substrate so as to cover the gate electrode;
- (c) planarizing a surface of the first ferroelectric film;
- (d) stacking, on the planarized first ferroelectric film, a second thin ferroelectric film having the same crystalline structure as the first ferroelectric film;
- (e) forming a semiconductor film on the second ferroelectric film;
- and
- (f) forming a source/drain electrode on the semiconductor film,
- wherein the first ferroelectric film and the second ferroelectric film constitute a ferroelectric stacked-layer structure which serves as a gate insulating film of the field effect transistor.
A method for fabricating a ferroelectric capacitor, comprising:
- (a) forming a first conductive film on a substrate;
- (b) forming a first polycrystalline ferroelectric film on the first conductive film;
- (c) planarizing a surface of the first ferroelectric film;
- (d) stacking, on the planarized first ferroelectric film, a second thin ferroelectric film having the same crystalline structure as the first ferroelectric film;
- and
- (e) forming a second conductive film on the second ferroelectric film,
- wherein the first ferroelectric film and the second ferroelectric film constitute a ferroelectric stacked-layer structure which serves as a capacitor film of the ferroelectric capacitor.
A field effect transistor of which a gate insulating film has a ferroelectric stacked-layer structure, the ferroelectric stacked-layer structure comprising:
- a first polycrystalline ferroelectric film;
- and
- a second thin ferroelectric film stacked on the first ferroelectric film,
- wherein the first ferroelectric film has a planarized surface,
- the second ferroelectric film has the same crystalline structure as the first ferroelectric film,
- a semiconductor film is further formed on the second ferroelectric film, and
- an interface between the second ferroelectric film and the semiconductor film serves as a channel of the field effect transistor.
A ferroelectric capacitor of which a capacitor film has a ferroelectric stacked-layer structure, the ferroelectric stacked-layer structure comprising:
- a first polycrystalline ferroelectric film;
- and
- a second thin ferroelectric film stacked on the first ferroelectric film,
- wherein the first ferroelectric film has a planarized surface, and
- the second ferroelectric film has the same crystalline structure as the first ferroelectric film.
Dependencies are inferred from the claim text.