Method of manufacturing a ferroelectric capacitor and a ferroelectric capacitor
View Patent ↗A lower electrode film is formed above a substrate. A ferroelectric film is formed above the lower electrode film. An amorphous intermediate film of a perovskite-type conductive oxide is formed above the ferroelectric film. A first upper electrode film comprising oxide of at least one metal selected from a group of Pt, Pd, Rh, Ir, Ru, and Os is formed on the intermediate film. The intermediate film is crystallized by carrying out a first heat treatment in an atmosphere containing an oxidizing gas after the formation of the first upper electrode film. After the first heat treatment, a second upper electrode film comprising oxide of at least one metal selected from a group of Pt, Pd, Rh, Ir, Ru, and Os is formed on the first upper electrode film, at a temperature lower than the growth temperature for the first upper electrode film.
1. A ferroelectric capacitor comprising:
a lower electrode formed above a substrate;
a ferroelectric film comprising columnar crystal grains, the ferroelectric film being located above the lower electrode;
an intermediate film located above the ferroelectric film and made of a perovskite-type conductive oxide, the intermediate film comprising columnar crystal grains;
a first upper electrode located above the intermediate film and made of oxide of at least one metal selected from a group consisting of Pt, Pd, Rh, Ir, Ru, and Os, the first upper electrode comprising columnar crystal grains; and
an amorphous or microcrystalline second upper electrode located above the first upper electrode and made of oxide of at least one metal selected from a group consisting of Pt, Pd, Rh, Ir, Ru, and Os.
2. The ferroelectric capacitor according to claim 1 , wherein the crystal grains in the intermediate film are distributed correspondingly to the crystal grains in the ferroelectric film.
3. The ferroelectric capacitor according to claim 1 , wherein a size of the crystal grains in the first upper electrode measured in an in-plane direction is smaller than a size of the crystal grains in the ferroelectric film measured in the in-plane direction.
4. The ferroelectric capacitor according to claim 1 , wherein the intermediate film has a thickness in a range of 1 nm to 5 nm.
5. The ferroelectric capacitor according to claim 1 , wherein the first upper electrode has a thickness in a range of 10 nm to 70 nm.
6. The ferroelectric capacitor according to claim 1 , wherein the crystal grains in the first upper electrode has a size in a range of 1 nm to 10 nm in an in-plane direction.
7. The ferroelectric capacitor according to claim 1 , wherein the intermediate film comprises a conductive material containing Sr, Ru, and O, a conductive material containing Sr, Ti, and O, a conductive material containing La, Sr, Mn, and O, or a conductive material containing La, Sr, Co, and O.