Claims
- 1. A ferro-electric capacitor comprising:a first electrode; a second electrode being isolated from said first electrode, a ferro-electric PZT layer being sandwiched between said first electrode and said second electrode; and wherein said first electrode comprises at least a layer of a conductive oxide having at least two sub-layers of individual grains, the top sub-layer having a random orientation of individual grains, the grain size of said conductive oxide layer being at most 20 nm.
- 2. The ferro-electric capacitor of claim 1, wherein said PZT layer has a predetermined orientation.
- 3. The ferro-electric capacitor of claim 1, wherein said conductive oxide layer is made of a unary oxide, preferably having a rutile crystal structure such as IrO2, RuO2, RhO2, ReO2, or OsO2.
- 4. The ferro-electric capacitor of claim 1, wherein said conductive oxide layer is made of a complex oxide having a perovskite crystal layer such as (La,Sr)CoO3.
- 5. The ferro-electric capacitor of claim 1, wherein said PZT layer comprises a first PZT sub-layer and a second PZT sub-layer, a Ti-concentration of the first PZT sub-layer being higher than a Ti-concentration of the second PZT sub-layer.
- 6. The ferro-electric capacitor of claim 1, wherein said PZT layer has the form of one horizontal surface with sidewalls overlapping said first electrode.
- 7. The ferro-electric capacitor of claim 1, being connected to an electrode or an active device through a via connection.
- 8. The device comprising an active device and a MOSFET on which are deposited at least a contact layer, a conductive via connection and a ferro-electric capacitor according to claim 1.
- 9. A method of fabricating a ferro-electric capacitor of claim 1, comprising:creating on a substrate a first electrode consisting essentially in a layer of a conductive oxide; forming a ferro-electric PZT layer on said conductive oxide layer; creating a second electrode isolated from said first electrode on the top of the ferro-electric PZT layer; wherein said conductive oxide layer comprises at least two sub-layers of individual grains, the top sub-layer having a random orientation of individual grains, the grain size of the conductive oxide layer being at most 20 nm.
- 10. The method of claim 9, wherein the step of forming a ferro-electric PZT layer consists in:deposition of an amorphous PZT layer; and crystallization of said amorphous layer into a ferro-electric PZT layer by a thermal treatment.
- 11. The method of claim 9, further comprising, before creating the first electrode:depositing a contact layer on an active device; and depositing a conductive via connection on said contact layer.
- 12. The method of claim 9, wherein the temperature of the substrate during the growing of the PZT layer is comprised between a first predetermined temperature Tc1 and a second predetermined temperature Tc2, Tc1 being defined by the temperature below which the sub-layers of the conductive oxide layer being amorphous, Tc2 being defined by the temperature which ensures that the grain size of the PZT layer does not exceed a predetermined dimension on the order of 20 nn.
- 13. The method of claim 9, wherein the atmosphere during the growing of the PZT layer is a O2/Ar mixing atmosphere having a ratio above 1 and preferably above 4/1.
- 14. The method of claim 9, wherein the deposition rate of the PZT layer during the growth is comprised in a range 15-20 nm/min.
- 15. The method of claim 9, wherein said conductive oxide layer has a grain size at least two times and preferably five times smaller than the PZT layer thickness.
Priority Claims (1)
Number |
Date |
Country |
Kind |
99870224 |
Oct 1999 |
EP |
|
Parent Case Info
This application claims priority under 35 U.S.C. § 119 to U.S. Provisional Application No. 60/110,276 filed on Nov. 30, 1998, and to European Patent Application No. 99870224.5 filed on Oct. 26, 1999.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/BE99/00155 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO00/33361 |
6/8/2000 |
WO |
A |
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Date |
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5234641 |
Rutt |
Aug 1993 |
A |
5572052 |
Kashihara et al. |
Nov 1996 |
A |
6303490 |
Jeng |
Oct 2001 |
B1 |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/110276 |
Nov 1998 |
US |