Semiconductor memory device with a capacitor having a protection layer
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorNaoto Matsuo
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Abstract
A semiconductor memory device in which a protection layer is disposed between a silicon storage electrode and a tantalum pentoxide dielectric layer. A conductive material having a larger free energy of oxide formation than that of the tantalum pentoxide is used for forming the protection layer. Therefore, no native oxide film is formed at the interface between the storage electrode and the dielectric layer. As a result, the dielectric constant of the dielectric layer does not decrease even when the dielectric layer is a thin film.
Claims9
A semiconductor memory device comprising a plurality of memory cells each having a switching transistor and a storage capacitor, said storage capacitor comprising:
- a first electrode electrically connected to said switching transistor, said first electrode having a top face and a side face;
- a protection layer formed on said first electrode;
- a dielectric layer formed on said protection layer, said dielectric layer being made of a first metal oxide;
- and
- a second electrode formed on said dielectric layer;
- wherein said protection layer consists of a refractory metal with a lower tendency to oxidize as compared to the oxide-forming tendency of the metal of said first metal oxide, and said protection layer covers said top face and said side face of said first electrode.
A semiconductor memory device comprising a plurality of memory cells each having a switching transistor and a storage capacitor, said storage capacitor comprising:
- a first electrode electrically connected to said switching transistor;
- a dielectric layer formed on said first electrode, said dielectric layer being made of a first metal oxide;
- and
- a second electrode formed on said dielectric layer wherein said second electrode includes at least a first layer formed on said dielectric layer and a second layer formed on said first layer, said first layer being made of a material which has a lower tendency to oxidize as compared to the oxide-forming tendency of the metal of said first metal oxide, said second layer covering entirely a top face of said first layer;
- wherein said first electrode comprises a conductive material with a lower tendency to oxidize as compared to the oxide-forming tendency of the metal of said first metal oxide.
Dependencies are inferred from the claim text.