Semiconductor device and method of manufacturing the semiconductor device
View Patent ↗An upper electrode of a ferroelectric capacitor has a first layer formed of a first oxide expressed by a chemical formula AO x1 (A: metal, O: oxygen) using a stoichiometric composition parameter x 1 , and expressed by a chemical formula AO x2 using a actual composition parameter x 2 , and a second layer formed of a second oxide, formed on the first layer, expressed by a chemical formula BO y1 (B: metal) using a stoichiometric composition parameter y 1 and expressed by a chemical formula BO y2 using a actual composition parameter y 2 , which includes at least one of stone-wall crystal and column crystal.
1. A method of manufacturing a semiconductor device, comprising:
forming a lower electrode over a semiconductor substrate;
forming a ferroelectric film on the lower electrode;
forming a first conductive oxide film on the ferroelectric film; and
forming a second conductive oxide film on the first conductive oxide film;
wherein the first conductive oxide film is formed under a condition that a rate of an oxygen flow rate to a an inert gas flow rate is smaller than a rate of an oxygen flow rate to a an inert gas flow rate to form the second conductive oxide film, and
the second conductive oxide film is formed under a condition that a temperature of the semiconductor substrate is controlled within a range in which stone-wall microcrystal oxides are formed and then column microcrystal oxides are formed by joining the stone-wall microcrystal oxides.
2. The method of claim 1 , wherein
forming a third layer, which is formed of one of noble metal, alloy including noble metal, and oxide of at least one of noble metal and alloy including noble metal, on the second conductive oxide film.
3. The method of claim 1 , wherein
after forming the ferroelectric film but before forming the first conductive oxide film,
annealing the ferroelectric film at a first temperature in an atmosphere including inert gas and oxidizing gas; and
crystallizing the ferroelectric film by annealing the ferroelectric film at a second temperature higher than the first temperature in an atmosphere including an oxygen.
4. The method of claim 1 , wherein
after forming the ferroelectric film but before forming the first conductive oxide film, annealing the ferroelectric film at a first temperature in an atmosphere including inert gas and oxidizing gas; and
after forming the first conductive oxide film, crystallizing the ferroelectric film by annealing the ferroelectric film at a second temperature higher than the first temperature in an atmosphere including oxygen.
5. The method of claim 1 , wherein
after forming the ferroelectric film but before forming the first conductive oxide film, annealing the ferroelectric film at a first temperature in an atmosphere including inert gas and oxidizing gas, and forming an amorphous ferroelectric film, which is thinner than the ferroelectric film, on the ferroelectric film crystallized; and
after forming the first conductive oxide film, crystallizing the ferroelectric film by annealing the ferroelectric film at a second temperature higher than the first temperature in an atmosphere including oxygen.
6. The method of claim 1 , wherein
after forming the ferroelectric film but before forming the first conductive oxide film, annealing the ferroelectric film at a first temperature in an atmosphere including an oxidizing gas, and forming an amorphous ferroelectric film that is thinner than the ferroelectric film; and
after forming the first conductive oxide film, crystallizing the ferroelectric film by annealing the ferroelectric film at a second temperature higher than the first temperature in an atmosphere including oxygen.
7. The method of claim 1 , wherein
after forming the second conductive oxide film, annealing the second conductive oxide film at a third temperature which makes high adhesion of the ferroelectric film and the first and second conductive oxide films, in an atmosphere including oxygen.
8. The method of claim 1 , wherein
the second conductive oxide film is formed by a sputtering technique using a target including at least one of noble metal elements chosen from a consisting of platinum, iridium, ruthenium, rhodium, rhenium, osmium, and palladium, under a condition in which oxidation of the noble metal element is formed.
9. The method of claim 1 , wherein
the second conductive oxide film is formed of microcrystal by controlling a film forming temperature.
10. The method of claim 1 , wherein
the second conductive oxide film is formed by setting a film forming temperature of 30 ° C. to 100° C.
11. The method of claim 1 , wherein
the second conductive oxide film is formed by setting a film forming temperature of 50 ° C. to 75° C.
12. The method of claim 1 , wherein a film thickness of the first conductive oxide film is thinner than a film thickness of the second conductive oxide film.
13. The method of claim 8 , wherein a film thickness of the second layer is set to 125 nm to 150 nm.