Memory applications based on ferroelectric and high-permittivity dielectric thin films

Jones, Robert E.; Zürcher, P.; Chu, Peir; Taylor, Deborah J.; Lii, Y. T.; Jiang, Bo; Maniar, P.; Gillespie, S.J.

doi:10.1016/0167-9317(95)00106-9

Cited by 62 publications

(26 citation statements)

References 9 publications

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“…The recent development of ferroelectric thin films of the Pb(Zr,Ti)O 3 (PZT) family for memory [1], piezoelectric [2] and pyroelectric [3,4] devices has drawn considerable interest to integration issues. The prime concern is bottom electrode stability against the conditions prevailing during PZT film in-situ growth or crystallization annealing: oxidizing ambients and the presence of lead oxide at high temperatures (550-700°C).…”

Section: Introductionmentioning

confidence: 99%

Stabilized Platinum Electrodes for Ferroelectric Film Deposition using Ti, Ta and Zr Adhesion Layers

Maeder¹,

Sagalowicz²,

Muralt³

1998

Jpn. J. Appl. Phys.

111

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Pt-based metallizations using different adhesion layers (Ti, Zr and Ta) were studied for use as electrodes for ferroelectric thin films on oxidized silicon substrates. Different ways of oxidizing the adhesion layers prior to ferroelectric film growth are compared, with regard to obtaining stable, adherent Pt films of well-defined (111) orientation, while avoiding lead diffusion through the electrode. Upon in-situ deposition of PbTiO 3 at high excess lead flux, lead diffusion through the Pt film was found to depend strongly on the adhesion layer and the stabilization treatment. Pre-oxidation reduces lead diffusion during the later processing. Ti diffuses through the electrode for oxidation reaction, whereas Ta and Zr stay in place, in analogy to the diffusivities in the corresponding oxides. A novel oxidation treatment was developed to produce stable, adherent metallizations with controlled orientation and good barrier properties against lead diffusion.

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Section: Introductionmentioning

confidence: 99%

Stabilized Platinum Electrodes for Ferroelectric Film Deposition using Ti, Ta and Zr Adhesion Layers

Maeder¹,

Sagalowicz²,

Muralt³

1998

Jpn. J. Appl. Phys.

111

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“…La demanda de memorias de capacidad creciente manteniendo, o incluso reduciendo, las dimensiones, exige el uso de materiales de permitividad dielŽctrica creciente. Los -xidos ferroelŽctricos, con permitividades dos -rdenes de magnitud mayores que los compuestos SiO 2 /Si 3 N 4 actualmente utilizados, son los principales candidatos (1). Las composiciones id-neas son aquellas que presentan la transici-n ferro-paraelŽctrica a temperatura ambiente, ya que la anomal'a dielŽctrica lleva asociada valores altos de la permitividad, y desorden en la ocupaci-n de uno de los sitios de la estructura, lo que se traduce en una transici-n difusa y, por tanto, en que los valores de permitividad altos se mantengan en un intervalo de temperaturas apreciable.…”

Section: Introducciînunclassified

Láminas delgadas ferroeléctricas de titanato de plomo modificado con un 20% de lantano

Algueró¹,

Calzada²,

Pardo³

1999

Bol. Soc. Esp. Ceram. Vidr.

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Se han preparado l ‡minas delgadas ferroelŽctricas de titanato de Pb modificado con un 20% de La, Pb 0.7 La 0.2 TiO 3 , por una tŽcni-ca sol-gel basada en la ruta de los dioles. Se ha variado el contenido inicial de PbO, del nominal a un exceso del 20% molar; y la velocidad de calentamiento en el tratamiento tŽrmico de cristalizaci-n a 650 o C, de 10 o C min -1 a m ‡s de 500 o C min -1 , y estudiado su efecto en la microestructura, estructura y composici-n de las l ‡minas. No es posible obtener l ‡minas monof ‡sicas con el tratamiento con 10 o C min -1 , aun compensando la volatilizaci-n de PbO con un exceso inicial del 20% molar. S' lo es con tratamiento r ‡pido manteniendo dicho exceso de PbO. Estas oeltimas l ‡minas presentan una permitividad dielŽctrica a temperatura ambiente de ε=700, y una variaci-n entre ambiente y 100 o C de ∆ε= 75, par ‡metros muy interesantes para memorias DRAMs.Palabras clave: l ‡minas ferroelŽctricas, Pb 0.7 La 0.2 TiO 3 , memorias DRAM Lead titanate ferroelectric thin films modified with 20% lanthanumLanthanum modified lead titanate ferroelectric thin films with a composition Pb 0.7 La 0.2 TiO 3 have been prepared by a diol based sol-gel technique. The effect on the film structure, microstructure and composition of the initial PbO content, from the nominal value to an excess of 20 mole%, and of the heating rate of the thermal treatment of crystallisation at 650 o C, from 10 o C min -1 to more than 500 o C min -1 , has been studied. It is not possible to obtain single phase films with the treatment at 10 o C min -1 , even when PbO volatilisation is compensated with an initial excess of PbO of 20 mole%. It is possible with the treatment at more than 500 o C min -1 and the latter excess of PbO. These films present a relative dielectric permittivity at room temperature of ε= 700, and a variation between room temperature and 100 o C of ∆ε= 75, being both parameters very interesting for DRAMs.Key words: ferroelectric films, Pb 0.7 La 0.2 TiO 3 , DRAMs INTRODUCCIîNEn las memorias din ‡micas de acceso aleatorio (DRAMs) el elemento activo es un condensador, y los dos estados de la memoria se definen como los estados cargado y descargado del condensador. La demanda de memorias de capacidad creciente manteniendo, o incluso reduciendo, las dimensiones, exige el uso de materiales de permitividad dielŽctrica creciente. Los -xidos ferroelŽctricos, con permitividades dos -rdenes de magnitud mayores que los compuestos SiO 2 /Si 3 N 4 actualmente utilizados, son los principales candidatos (1). Las composiciones id-neas son aquellas que presentan la transici-n ferro-paraelŽctrica a temperatura ambiente, ya que la anomal'a dielŽctrica lleva asociada valores altos de la permitividad, y desorden en la ocupaci-n de uno de los sitios de la estructura, lo que se traduce en una transici-n difusa y, por tanto, en que los valores de permitividad altos se mantengan en un intervalo de temperaturas apreciable. El material m ‡s investigado es el titanato de bario modificado con estroncio (BST), alrededor de la com...

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“…Potential applications of BST include high density dynamic random access memory (DRAM) [1], ferroelectric random access memory (FERAM) [2] and tunable microwave components [3]. The high, field dependent permittivity and low loss tangent of BST make it attractive as a dielectric material for electronically controlled microwave devices such as filters, phase shifters and matching networks [4].…”

Section: Introductionmentioning

confidence: 99%

Low Cost Interdigital BST Varactors for Tunable Microwave Applications

Fardin

Ghorbani

Holland

2005

TENCON 2005 - 2005 IEEE Region 10 Conference

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Abstract-In this paper, a simple and inexpensive technique for the fabrication of barium strontium titanate (BST) varactors is presented. BST films were deposited using RF magnetron sputtering on platinum coated silicon substrates. The advantages of silicon include low cost and ease of integration with existing fabrication processes. The microstructural properties of the BST layer were examined with scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) techniques. Gold top layer electrodes were deposited using DC sputtering and patterned with a conventional photolithographic process. The S-parameters of the varactor were measured from 40 MHz to 20 GHz on a vector network analyser. From this data, the capacitance, tunability and Q-factor of the device were extracted. The BST-based varactors show potential for integration into electronically tunable microwave circuits.

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Memory applications based on ferroelectric and high-permittivity dielectric thin films

Cited by 62 publications

References 9 publications

Stabilized Platinum Electrodes for Ferroelectric Film Deposition using Ti, Ta and Zr Adhesion Layers

Stabilized Platinum Electrodes for Ferroelectric Film Deposition using Ti, Ta and Zr Adhesion Layers

Láminas delgadas ferroeléctricas de titanato de plomo modificado con un 20% de lantano

Low Cost Interdigital BST Varactors for Tunable Microwave Applications

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