Patent US6265230B1 successfully refreshed from Google Patents.
US6265230B1
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US
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Methods to cure the effects of hydrogen annealing on ferroelectric capacitors
Assignee: University of Maryland, College Park
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Filing: 2000-01-20
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Granted: 2001-07-24
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Expires: 2020-01-20
Abstract
Abstract A ferroelectric memory cell integrated with silicon circuitry which require a forming-gas anneal of the silicon circuitry after the ferroelectric stack has been formed. The ferroelectric layer may have a composition such that there is no space in the lattice of the ferroelectric phase to accommodate atomic hydrogen or have a composition with a Curie temperature below the temperature of the forming-gas anneal. Preferably, there is no upper platinum electrode, or it is deposited after the forming-gas anneal. A metal-oxide upper electrode serves as barrier to the forming-gas anneal, and an intermetallic layer positioned above the ferroelectric stack serves as an even better barrier. Forming-gas damage to the ferroelectric stack can be removed by a recovery anneal in a hydrogen-free environment, preferably performed at a temperature above the Curie temperature.
Inventors
- 👤 Sanjeev Aggarwal
- 👤 Scott Robert Perusse
- 👤 Ramamoorthy Ramesh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:57
CPC Classifications
H; H04; H04Q; H04Q11/00; H04Q11/04; H04Q11/0428; H04Q11/0478; H04L; H04L49/00; H04L49/30; H04L49/3081; H10; H10D; H10D1/00; H10D1/60; H10D1/68; H10D1/682; H10D1/692; H10D1/696; H04L12/00; H04L12/54; H04L12/56; H04L12/5601; H04L2012/5629; H04L2012/5631; H04L2012/5636
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
117 words
A process for treating a substrate comprising a ferroelectric memory cell including a ferroelectric stack having a ferroelectric layer formed over a lower electrode layer and integrated on a silicon integrated circuit in said substrate, comprising the steps of: after the formation of active circuits in said silicon integrated circuit and of oxide portions of said ferroelectric stack, a first step of annealing said substrate at an elevated first temperature in an environment containing hydrogen; and a subsequent second step of annealing said substrate at an elevated second temperature in a hydrogen-free environment, wherein said hydrogen-free environment is at essentially atmospheric pressure and comprises an oxygen content in the range of 1 to 100 ppm by volume.
Claim 2
Dependent Claim
117 words
A process for treating a substrate comprising a ferroelectric memory cell including a ferroelectric stack having a ferroelectric layer formed over a lower electrode layer and integrated on a silicon integrated circuit in said substrate, comprising the steps of: after the formation of active circuits in said silicon integrated circuit and of oxide portions of said ferroelectric stack, a first step of annealing said substrate at an elevated first temperature in an environment containing hydrogen; and a subsequent second step of annealing said substrate at an elevated second temperature in a hydrogen-free environment, wherein said hydrogen-free environment is at essentially atmospheric pressure and comprises an oxygen content in the range of 1 to 100 ppm by volume.
Claim 3
Dependent Claim
116 words
A process for treating a substrate comprising a ferroelectric memory cell including a ferroelectric stack having a ferroelectric layer formed over a lower electrode layer and integrated on a silicon integrated circuit in said substrate, comprising the steps of: after the formation of active circuits in said silicon integrated circuit and of oxide portions of said ferroelectric stack, a first step of annealing said substrate at an elevated first temperature in an environment containing hydrogen; and a subsequent second step of annealing said substrate at an elevated second temperature in a hydrogen-free environment, wherein said hydrogen-free environment comprises an oxygen content in the range of 1 to 100 ppm by volume when measured at atmospheric pressure.
Claim 4
Dependent Claim
116 words
A process for treating a substrate comprising a ferroelectric memory cell including a ferroelectric stack having a ferroelectric layer formed over a lower electrode layer and integrated on a silicon integrated circuit in said substrate, comprising the steps of: after the formation of active circuits in said silicon integrated circuit and of oxide portions of said ferroelectric stack, a first step of annealing said substrate at an elevated first temperature in an environment containing hydrogen; and a subsequent second step of annealing said substrate at an elevated second temperature in a hydrogen-free environment, wherein said hydrogen-free environment comprises an oxygen content in the range of 1 to 100 ppm by volume when measured at atmospheric pressure.
Claim 5
Dependent Claim
134 words
A process for treating a substrate comprising a ferroelectric memory cell including a ferroelectric stack having a ferroelectric layer formed over a lower electrode layer and integrated on a silicon integrated circuit in said substrate, comprising the steps of: after the formation of active circuits in said silicon integrated circuit and of oxide portions of said ferroelectric stack, a first step of annealing said substrate at an elevated first temperature in an environment containing hydrogen; and a subsequent second step of annealing said substrate at an elevated second temperature in a hydrogen-free environment, thereby recovering polarization characteristics of said ferroelectric memory cell degraded in said first annealing step, wherein said hydrogen-free environment comprises a chemically inert gas and oxygen having a concentration of between 1 to 100 ppm by volume to said inert gas.
Claim 6
Dependent Claim
134 words
A process for treating a substrate comprising a ferroelectric memory cell including a ferroelectric stack having a ferroelectric layer formed over a lower electrode layer and integrated on a silicon integrated circuit in said substrate, comprising the steps of: after the formation of active circuits in said silicon integrated circuit and of oxide portions of said ferroelectric stack, a first step of annealing said substrate at an elevated first temperature in an environment containing hydrogen; and a subsequent second step of annealing said substrate at an elevated second temperature in a hydrogen-free environment, thereby recovering polarization characteristics of said ferroelectric memory cell degraded in said first annealing step, wherein said hydrogen-free environment comprises a chemically inert gas and oxygen having a concentration of between 1 to 100 ppm by volume to said inert gas.
Claim 7
Dependent Claim
108 words
A process for treating a substrate comprising a ferroelectric memory cell including a ferroelectric stack having a ferroelectric layer formed over a lower electrode layer and integrated on a silicon integrated circuit in said substrate, comprising the steps of: after the formation of active circuits in said silicon integrated circuit and of oxide portions of said ferroelectric stack, a first step of annealing said substrate at an elevated first temperature in an environment containing hydrogen; and a subsequent second step of annealing said substrate at an elevated second temperature in a hydrogen-free environment, wherein said hydrogen-free environment comprises at least 90% by volume of a chemically inert gas.
Claim 8
Dependent Claim
108 words
A process for treating a substrate comprising a ferroelectric memory cell including a ferroelectric stack having a ferroelectric layer formed over a lower electrode layer and integrated on a silicon integrated circuit in said substrate, comprising the steps of: after the formation of active circuits in said silicon integrated circuit and of oxide portions of said ferroelectric stack, a first step of annealing said substrate at an elevated first temperature in an environment containing hydrogen; and a subsequent second step of annealing said substrate at an elevated second temperature in a hydrogen-free environment, wherein said hydrogen-free environment comprises at least 90% by volume of a chemically inert gas.
Claim 9
Dependent Claim
20 words
The process of claim 4 , wherein said hydrogen-free environment comprises no more than 100 ppm by volume of oxygen.
Claim 10
Dependent Claim
13 words
The process of claim 4 , wherein said chemically inert gas comprises argon.
Claim 11
Dependent Claim
19 words
The process of claim 4 , wherein said hydrogen-free environment comprises no more than 1% of hydrogen by volume.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-07-23 | 2005-01-22 | 2005-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-07-23 | 2009-01-22 | 2009-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-07-23 | 2013-01-22 | 2013-07-24 | $7700.00 | Window Closed / Lapsed |