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US5789268A Expired / Lapsed US ⏱️ 0.0 years remaining

Method of forming a electrode structure for ferroelectric capacitors for integrated circuits

Assignee: RPX Clearinghouse LLC
•
Filing: 1996-10-10
•
Granted: 1998-08-04
•
Expires: 2016-10-10
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Abstract

Abstract An improved electrode structure compatible with ferroelectric capacitor dielectrics is provided. In particular, a multilayer electrode having improved adhesion to ferroelectric materials such as PZT is formed comprising a first layer of a noble metal, a second layer of another metal and a thicker layer of the noble metal, which are annealed to cause controlled interdiffusion of the layers forming a mixed metal surface layer having a rough interface with the dielectric layer. For example, the first two layers comprise relatively thin ˜200 Å layers of Pt and Ti, and then a thicker layer of the main, first, electrode material is deposited on top. Non-uniform interdiffusion of the layers during annealing causes intermixing of the Pt and Ti layers at the interfaces forming a Pt/Ti alloy having a rough surface. The rough surface, and particularly hillocks formed at the interface, penetrate into the ferroelectric films, and anchor the electrode material to the dielectric. Improved adhesion of the conductive electrode material improves integrity of this interface during subsequent processing.

Inventors

  • 👤 Vasanta Chivukula
  • 👤 Pak K. Leung

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-09 05:18
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/60; H10D1/68; H10D1/692; H10D1/682; H10D1/696

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 120 words
A method of forming an electrode structure for a ferroelectric capacitor having first and second conductive electrodes and a layer of ferroelectric dielectric disposed therebetween, the method comprising providing a multilayer conductive electrode structure on the ferroelectric dielectric layer by steps comprising: providing a first, thin layer of a noble metal, forming thereon a thin layer of another metal comprising one of titanium and chromium, and then providing another thicker layer of a noble metal thereon, and annealing at a temperature sufficient to cause interdiffusion of the noble metal and other metal, thereby roughening forming a mixed metal layer having a rough surface at the interface of electrode and the ferroelectric material for anchoring the electrode to the ferroelectric dielectric.
Claim 2
Independent Claim 120 words
A method of forming an electrode structure for a ferroelectric capacitor having first and second conductive electrodes and a layer of ferroelectric dielectric disposed therebetween, the method comprising providing a multilayer conductive electrode structure on the ferroelectric dielectric layer by steps comprising: providing a first, thin layer of a noble metal, forming thereon a thin layer of another metal comprising one of titanium and chromium, and then providing another thicker layer of a noble metal thereon, and annealing at a temperature sufficient to cause interdiffusion of the noble metal and other metal, thereby roughening forming a mixed metal layer having a rough surface at the interface of electrode and the ferroelectric material for anchoring the electrode to the ferroelectric dielectric.
Claim 3
Dependent Claim 48 words
A method according to claim 1 wherein the first layer of noble metal is sufficiently thick to provide a diffusion barrier for controlling interdiffusion of the other metal through the first layer whereby excessive diffusion of the other metal to form an oxide at the interface is inhibited.
Claim 4
Dependent Claim 34 words
A method according to claim 1 wherein a noble metal is selected from the group consisting of palladium and platinum, and the other metal is selected from the group consisting of titanium and chromium.
Claim 5
Dependent Claim 19 words
A method according to claim 1 where in the noble metal comprises platinum and the other metal comprises titanium.
Claim 6
Dependent Claim 45 words
A method according to claim 1 comprising providing a first layer of a noble metal of approximately 200 Å thickness, a thin layer the other metal of about the same thickness, and a second layer of the noble metal approximately 1000 Å thick formed thereon.
Claim 7
Dependent Claim 41 words
A method according to claim 4 comprising providing a first layer of a platinum of approximately 200 Å thickness, a thin layer, the titanium of about the same thickness, and a second layer of platinum approximately 1000 Å thick formed thereon.
Claim 8
Dependent Claim 17 words
A method according to claim 4 wherein annealing is carried out at 400° C. to 450° C.

References Cited (Backward Citations)

US5005102A Cited
US5393352A Cited
US5335138A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 2001-08-03 2002-02-02 2002-08-04 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2005-08-03 2006-02-02 2006-08-04 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2009-08-03 2010-02-02 2010-08-04 $7700.00 Window Closed / Lapsed

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