Semiconductor device and method of manufacturing same
View Patent ↗A semiconductor device includes a substrate and a ferroelectric capacitor including a lower electrode, a ferroelectric film, and an upper electrode. The upper electrode includes a first layer formed of an oxide whose stoichiometric composition is expressed as AOx 1 and whose actual composition is expressed as AOx 2 ; a second layer formed on the first layer and formed of an oxide whose stoichiometric composition is expressed as BOy 1 and whose actual composition is expressed as BOy 2 ; and a metal layer formed on the second layer. The second layer is higher in ratio of oxidation than the first layer. The composition parameters x 1 , x 2 , y 1 , and y 2 satisfy y 2 /y 1 >x 2 /x 1 , and the second layer includes an interface layer of the stoichiometric composition formed at an interface with the metal layer. The interface layer is higher in ratio of oxidation than the rest of the second layer.
1. A method of manufacturing a semiconductor device, the method including forming a ferroelectric capacitor, wherein:
said forming the ferroelectric capacitor includes
forming a lower electrode;
depositing a ferroelectric film on the lower electrode;
depositing a first conductive oxide film on the ferroelectric film;
crystallizing the first conductive oxide film in an oxidizing atmosphere;
depositing a second conductive oxide film in a microcrystalline state on the first conductive oxide film after said crystallizing;
crystallizing a surface of the second conductive oxide film in an oxidizing atmosphere; and
depositing a metal film on the second conductive oxide film after said crystallizing the surface thereof.
2. The method as claimed in claim 1 , wherein each of said crystallizing the first conductive oxide film and said crystallizing the surface of the second conductive oxide film is performed with a rapid heat treatment process with a ratio of an oxidizing gas in the oxidizing atmosphere being less than or equal to 30%.
3. The method as claimed in claim 2 , wherein the rapid heat treatment process is performed with the ratio of the oxidizing gas in the oxidizing atmosphere being more than or equal to 0.1% and less than or equal to 30%.
4. The method as claimed in claim 2 , wherein the rapid heat treatment process is performed with the ratio of the oxidizing gas in the oxidizing atmosphere being more than or equal to 1% and less than or equal to 20%.
5. The method as claimed in claim 1 , wherein said crystallizing the first conductive oxide film is performed at a temperature higher than or equal to 650° C. and lower than or equal to 750° C.
6. The method as claimed in claim 1 , wherein said crystallizing the surface of the second conductive oxide film is performed at a temperature higher than or equal to 650° C. and lower than or equal to 750° C.
7. The method as claimed in claim 1 , wherein said depositing the first conductive oxide film is performed by sputtering at a temperature higher than or equal to 150° C. and lower than or equal to 350° C., so that the first conductive oxide film formed is in a crystalline state.
8. The method as claimed in claim 1 , wherein said depositing the first conductive oxide film is performed by sputtering at a temperature higher than or equal to 10° C. and lower than or equal to 50° C., so that the first conductive oxide film formed is in an amorphous state.
9. The method as claimed in claim 1 , wherein said depositing the second conductive oxide film is performed by sputtering at a temperature higher than or equal to 50° C. and lower than or equal to 80° C., so that the second conductive oxide film formed is in an amorphous state.
10. The method as claimed in claim 1 , wherein each of the first and second conductive oxide films is an iridium oxide film.
11. The method as claimed in claim 1 , wherein said depositing the second conductive oxide film is performed so that the second conductive oxide film is 100 nm to 150 nm in thickness.
12. The method as claimed in claim 1 , wherein said depositing the first conductive oxide film is performed so that the first conductive oxide film is 20 nm to 75 nm in thickness.
13. The method as claimed in claim 1 , wherein a ratio of a flow rate of an oxidizing gas to a flow rate of an inert gas is less in said depositing the first conductive oxide film than in said depositing the second conductive oxide film, so that the second conductive oxide film is higher in ratio of oxidation than the first conductive oxide film.