Tungsten Oxide as a Gate Dielectric for Highly Transparent and Temperature‐Stable Zinc‐Oxide‐Based Thin‐Film Transistors

Lorenz, Michael; Wenckstern, Holger von; Grundmann, Marius

doi:10.1002/adma.201103087

Cited by 35 publications

(34 citation statements)

References 24 publications

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“…The obtained T 0 values are comparable with various other transition-metal oxides. [20][21][22][23][24][25] Equation ( 2) shows that the origin of the temperature shift between the two states is the density of states at the Fermi level, which can be estimated. In case of the partially switched state (Table 1 ), the density of states is one order of magnitude higher than that of the fully switched states.…”

Section: Communicationmentioning

confidence: 99%

Spintronic Functionality of BiFeO₃ Domain Walls

et al. 2014

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Anisotropic magnetoresistance at the BiFeO3 domain walls has been observed thanks to the realization of micro-devices that allow the direct magneto-transport characterization of the domain-walls. Anisotropic magnetoresistance of ferromagnetic metals has been a pillar in spintronic technology, and now it is evidenced at the conductive domain walls of an insulating ferroelectric material, which implies that domain walls become an electrically tunable nanospintronic object.

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Section: Communicationmentioning

confidence: 99%

Spintronic Functionality of BiFeO₃ Domain Walls

et al. 2014

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“…19 Consequently, a value for / ms ¼ À0: (1), with e i ¼ 80 being the relative dielectric permittivity of the gate insulator. 8 Fig. 3(b) and Table I contain the data of experimental values V exp on and the calculations of the turn-on voltages V th on .…”

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confidence: 99%

“…7 Accordingly, lower leakage currents and smaller gate sweep voltages DV SG in order to turn transistors on and off are feasible. Recently, 8 we demonstrated room-temperature deposited tungsten trioxide (WO 3 ) as a high-j gate dielectric in conjunction with n-ZnO channel material.…”

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Design rules of (Mg,Zn)O-based thin-film transistors with high-κ WO3 dielectric gates

Lorenz

Reinhardt

Wenckstern

et al. 2012

Applied Physics Letters

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We present a study on the design and optimization of metal-insulator-semiconductor field-effect transistors based on (Mg,Zn)O channel material with WO3 dielectric. The thickness of the dielectric and of the channel layer were adjusted independently to minimize the off-current density joff, the subthreshold slope (SS), and to modify the turn-on voltage. For optimized dielectric thickness, values of joff<10−8 A/cm2 and SS = 68 mV/decade were obtained. The variation of the (Mg,Zn)O-film thickness gives rise to a shift of the turn-on voltage: For 21 nm thick channels Von=−1.68V is obtained and by reducing the thickness to 8.6 nm Von=−0.27V. Using a Pt gate metal, normally off transistors with Von=0.19V were realized.

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“…Furthermore, tungsten has recently been adapted as inverted-T refractory metal gate material where a relatively dense layer of chemical vapor deposition (CVD) tungsten is deposited on top of a thinner layer of less dense refractory metal, such as sputter deposition tungsten to promote adherence to a gate oxide layer grown on a silicon substrate. 9,10 Hence the characterization of tungsten oxide protective nano-films is important for both the subtractive and additive approaches in microelectronics manufacturing. Although it is known that the P-B ratio of tungsten is not protective in air (3.38 for WO 3 11 ) earlier CMP studies through electrochemical evaluations on tungsten demonstrated that it forms a protective oxide during the CMP applications.…”

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Characterization of Nano-Scale Protective Oxide Films: Application on Metal Chemical Mechanical Planarization

Karagoz

Crăciun

Basim

2014

ECS J. Solid State Sci. Technol.

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This study focuses on the characterization of nano-scale metal oxide films for chemical mechanical planarization (CMP) applications. The protective nature of the self-grown metal oxide layers in the CMP slurry environment enable topographic selectivity required for metallization of interconnects. Tungsten was selected as the model metal film to study the formation and characteristics of the metal oxide nano-layers since tungsten CMP is very well-established in conventional semiconductor manufacturing. The tungsten oxide nano-films were characterized for thickness, density and surface topography in addition to evaluation of their protective nature by calculation of the Pilling-Bedworth (P-B) ratios. It was observed that in addition to controlling the self-protective characteristics, the oxidizer concentration also affects the surface structure of the metal oxide films resulting in significant changes in the CMP process performance in terms of material removal rates and surface finish with a sweet-spot detected at 0. Nano-scale protective metal oxides are foreseen to have wide applications in advanced materials science and technology including microelectronics and biomaterials applications in addition to their conventional utilizations in corrosion prevention and coatings. Particularly in semiconductor manufacturing, controlled growth of thin films and inherent stress development within the film and film/substrate interface are very critical to enable the future material demands. Metal oxide thin films can be used as an interfacial layer to improve the adhesion of polymeric substances in chip packaging, as nano-films with inherent self-growth limiting capability for bottom-up microelectronics manufacturing or as a subtractive layer to achieve controlled material removal rates and minimum defectivity in chemical mechanical planarization (CMP) applications. CMP is the process of choice for planarization of metal and dielectric surfaces to enable precise photolithography and multilevel metallization in microelectronics manufacturing.1 Introduction of new automotive, medical and implantable devices challenge the needs to improve microelectronic device performances to meet aggressive targets on cost reduction, zero defectivity and enhanced reliability, which consecutively impact CMP process performance requirements.2 Although mainstream semiconductor engineering could involve tradeoffs between performance and reliability, these new applications enforce the assessment of new materials while dealing with limited margins requiring advances in processing, materials science and chemistry.3 The main objective of this paper is to characterize the self-protective oxide films grown on the metal surfaces in the presence of an oxidizing environment to be able to utilize them in advanced microelectronics manufacturing applications, predominantly focusing on CMP.When characterizing the durability of thin film interfaces, a critical thickness is defined above which it is thermodynamically favorable for the film to partially or fully...

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Tungsten Oxide as a Gate Dielectric for Highly Transparent and Temperature‐Stable Zinc‐Oxide‐Based Thin‐Film Transistors

Cited by 35 publications

References 24 publications

Spintronic Functionality of BiFeO₃ Domain Walls

Spintronic Functionality of BiFeO₃ Domain Walls

Design rules of (Mg,Zn)O-based thin-film transistors with high-κ WO3 dielectric gates

Characterization of Nano-Scale Protective Oxide Films: Application on Metal Chemical Mechanical Planarization

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Tungsten Oxide as a Gate Dielectric for Highly Transparent and Temperature‐Stable Zinc‐Oxide‐Based Thin‐Film Transistors

Cited by 35 publications

References 24 publications

Spintronic Functionality of BiFeO3 Domain Walls

Spintronic Functionality of BiFeO3 Domain Walls

Design rules of (Mg,Zn)O-based thin-film transistors with high-κ WO3 dielectric gates

Characterization of Nano-Scale Protective Oxide Films: Application on Metal Chemical Mechanical Planarization

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Spintronic Functionality of BiFeO₃ Domain Walls

Spintronic Functionality of BiFeO₃ Domain Walls