The platinum doped MOST: A memory storage element

Nassibian, A.G.; Jordan, D. O.; Golja, B.; Simmons, J.G.

doi:10.1109/t-ed.1981.20477

Cited by 7 publications

(2 citation statements)

References 4 publications

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“…Mobile ions cause threshold voltage shifts when impurities are incorporated into the Si02 and under DC bias diffuse to the gate or the Si02 interface. Typical elements that cause this problems are Na and K. Pt is a known mobile charge [128,129] and has even been used to make a nonvolatile memory device [130). Much less is known about Ru, Jr and Ba.…”

Section: Si and Si02 Degradationmentioning

confidence: 99%

(Ba,Sr)TiO3 Thin Films for Dram’s

Summerfelt

1997

Thin Film Ferroelectric Materials and Devices

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Section: Si and Si02 Degradationmentioning

confidence: 99%

(Ba,Sr)TiO3 Thin Films for Dram’s

Summerfelt

1997

Thin Film Ferroelectric Materials and Devices

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“…A similar clockwise hysteresis has also been reported in the MOS structure made with Pt-diffused-in gate oxide. [16][17][18][19] Unfortunately, its mechanism was not really discussed in the above-mentioned works.…”

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confidence: 99%

Memory characteristics of Pt nanocrystals self-assembledfrom reduction of an embedded PtOx ultrathin film in metal-oxide-semiconductor structures

Tseng

Cheng

Wang

et al. 2004

Applied Physics Letters

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The nonvolatile memory characteristics of metal-oxide-semiconductor structures containing Pt nanocrystals in SiO 2 gate oxide were studied. The Pt nanocrystals of 2 -3 nm in diameter were self-assembled from reduction of an ultrathin PtO x layer embedded in the SiO 2 by vacuum annealing at 425°C. A large hysteresis loop was found in the capacitance-voltage ͑C -V͒ relation indicating this significant memory effect. However, two different charge storage mechanisms were found for the Pt nanocrystals in devices with different tunnel oxide thickness. A counterclockwise C -V hysteresis was induced from substrate injection for the devices made with a thin tunnel oxide layer 2.5-5.0 nm thick. Contrast, a clockwise behavior attributed to the electron transfer from charged defects in the gate oxide was found for the devices having a tunnel oxide layer 7.5 nm thick. The relatively stable memory characteristics of Pt nanocrystals resulted from substrate injection were also demonstrated.Memory-cell structures employing semiconductor or metal nanocrystals as storage elements in metal-oxidesemiconductor (MOS) field effect transistors have attracted much attention due to their properties as nonvolatile memory devices. [1][2][3][4] Most research has focused on the fabrication of Si or Ge nanocrystals in MOS structure, 1-7 but the metalnanocrystal memories are considered to be more beneficial in many aspects. [8][9][10][11][12] The metal nanocrystals have usually been fabricated by annealing an ultrathin metal film deposited on the thin gate oxide of SiO 2 . 8-12 However, the thermal and mechanical incompatibility between metal films and SiO 2 makes the fabrication of discrete and uniformly sized metal nanocrystals in gate oxide quite difficult. It is known that the oxidized phase of noble metals, such as PtO x , is chemically unstable, and can be easily reduced back to metallic state. 13 Accordingly, a self-assembly process of Pt nanocrystal formation from the reduction of an ultrathin PtO x layer embedded in SiO 2 is reported, and its memory characteristics are studied in this work.A trilayer structure containing a thin tunnel oxide layer of SiO 2 , an ultrathin PtO x layer, and a control oxide layer of SiO 2 was prepared. The tunnel oxide layer 2.5-7.5 nm thick was grown at 800°C in pure oxygen on ͑100͒ p-type ͑1-10 ⍀ cm͒ Si. The PtO x layer ϳ4 nm thick and the control oxide layer 24 or 36 nm thick, were deposited subsequently at room temperature by rf-magnetron sputtering with a low rf power giving a deposition rate of 2 nm/ min. All the MOS devices were then annealed at 425°C for 25 min in vacuum, which resulted in a reduction of the ultrathin PtO x layers into discrete Pt nanocrystals embedded in SiO 2 matrix. Figure 1(a) shows the cross-sectional image of transmission electron microscopy (TEM) of the Pt nanocrystals self-assembled in the SiO 2 matrix. Note that the Pt nanocrystals were mostly spherical with a narrow size distribution in the range of 2 -3 nm, as depicted in Fig. 1(b). The chemical state of Pt in the vacuum-a...

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Effect of the Si‐SiO₂ interface state density and the charge in the SiO₂ film on the electrical properties in Pt–diffused MOS structure

Kato

Shibata

Kuwano

1987

Electron Comm Jpn Pt II

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The effect of Pt‐diffusion on the electrical properties in the Pt‐diffused MOS structure has been investigated. In these structures, the Pt‐diffusion ambient has a direct effect on the electrical properties;, the samples which were Pt‐diffused in oxygen ambient show a large positive flatband voltage shift, and those which were Pt‐diffused in nitrogen ambient show little flatband voltage shift but have a memory effect. We measured the dependence of flatband voltage on the oxide thickness and evaluated the distribution of the Si‐SiO2 interface state density. We also measured the oxide charge density. From these experimental results, we show that the large shift of the flatband voltage is caused mainly by the charges generated within the oxide film and that the Si‐SiO2 interface state density distribution varies reversibly according to the memory effect.

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The platinum doped MOST: A memory storage element

Cited by 7 publications

References 4 publications

(Ba,Sr)TiO3 Thin Films for Dram’s

(Ba,Sr)TiO3 Thin Films for Dram’s

Memory characteristics of Pt nanocrystals self-assembledfrom reduction of an embedded PtOx ultrathin film in metal-oxide-semiconductor structures

Effect of the Si‐SiO₂ interface state density and the charge in the SiO₂ film on the electrical properties in Pt–diffused MOS structure

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The platinum doped MOST: A memory storage element

Cited by 7 publications

References 4 publications

(Ba,Sr)TiO3 Thin Films for Dram’s

(Ba,Sr)TiO3 Thin Films for Dram’s

Memory characteristics of Pt nanocrystals self-assembledfrom reduction of an embedded PtOx ultrathin film in metal-oxide-semiconductor structures

Effect of the Si‐SiO2 interface state density and the charge in the SiO2 film on the electrical properties in Pt–diffused MOS structure

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Effect of the Si‐SiO₂ interface state density and the charge in the SiO₂ film on the electrical properties in Pt–diffused MOS structure