Tetragonal Phase Stabilization by Doping as an Enabler of Thermally Stable HfO2 based MIM and MIS Capacitors for sub 50nm Deep Trench DRAM

Böscke, T. S.; Govindarajan, S.; Fachmann, Christian; Heitmann, Johannes; Schröder, Uwe; Kudelka, S.; Kirsch, P. D.; Krug, Cristiano; Hung, Pui Yee; Song, S.C.; Ju, B.S.; Price, Jonathan G.; Pant, G.; Gnade, Bruce E.; Krautschneider, Wolfgang H.; Lee, B.-H.; Jammy, R.

doi:10.1109/iedm.2006.347011

Cited by 22 publications

(20 citation statements)

References 8 publications

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“…The significant difference in electrical properties is believed to be associated with the difference in crystalline structure after hightemperature annealing. Böscke et al 8 also observed similar phenomenon on HfO 2 -based dielectric.…”

Section: Materials Propertysupporting

confidence: 57%

Evaluation of Gadolinium Oxide as a Blocking Layer of Charge-Trap Flash Memory Cell

Kim

et al. 2008

Electrochem. Solid-State Lett.

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A rare-earth oxide, Gd 2 O 3 , is evaluated for the application of the blocking layer in polysilicon-oxide-silicon nitride-oxide-silicontype flash memory cell devices because of its high conduction-band offset and reasonably large value. In a Gd 2 O 3 /Si 3 N 4 /SiO 2 dielectric stack, a monoclinic-structured Gd 2 O 3 shows the advantage of faster program/erase speed with comparable charge retention when compared to a conventional Al 2 O 3 blocking layer. Such performance makes Gd 2 O 3 a promising high-material for the blocking layer in charge-trap flash memory devices.The introduction of high-k dielectrics to polysilicon-oxidesilicon nitride-oxide-silicon ͑SONOS͒-type flash memory device is imperative in flash-memory-device scaling. Using high-k dielectric for the blocking oxide layer, the electric field across the blocking oxide is proportionally reduced with its dielectric constant. Thus, electron injection from the gate during erase can be effectively suppressed. This also enables us to use a thicker tunnel oxide for better retention properties for the same program/erase ͑P/E͒ speed or to reduce P/E voltage. Faster P/E operation speed has been demonstrated by introducing Al 2 O 3 for the blocking oxide device. 1 However, a relatively low value ͑ϳ9͒ of Al 2 O 3 imposes a limitation for further scaling as well as performance enhancement. Among all the high-dielectric candidates, rare-earth oxides are recently of interest in research for complementary metal oxide semiconductor applications of high-dielectrics because of large energy bandgaps and relatively large dielectric constants. 2,3 Among them, Gd 2 O 3 possesses desirable properties for flash-memory-device application, such as a relatively high dielectric constant of 16-18, 3 a large bandgap of up to 7.0 eV, 4,5 and a large conduction band offset of 2.21-3.1 eV with regard to silicon 6 such that electron tunneling can effectively be blocked. Moreover, it has good thermal stability with Si up to 900°C with reasonably low leakage current. 7 In this paper, electrical properties of Gd 2 O 3 and its feasibility as the blocking layer in SONOS-type flash memory devices are studied. Material PropertyGd 2 O 3 films are deposited by sputtering using either Gd 2 O 3 oxide target in a pure Ar ambient or Gd metal target in an Ar/O 2 ambient. In both conditions, the chamber pressure is set to be 3 mTorr with 25 sccm Ar flow rate. There is no substrate heating during sputtering for both cases. The oxygen flow rate is set to be 3 sccm when sputtered using Gd metal target. X-ray diffraction ͑XRD͒ analysis is performed for film-morphology analysis. The measurements were carried out using a general area detector diffraction system equipped with Cu K␣ X-ray ͑ = 1.5418 Å͒. Figure 1a shows the XRD spectrum of Gd 2 O 3 film sputtered using Gd 2 O 3 oxide target. It shows that the as-deposited Gd 2 O 3 film is amorphous when sputtered using the oxide target. Once the film is annealed at a temperature in the range of 500-850°C, it forms a cubic crystal structure. For Gd 2 O 3 die...

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Section: Materials Propertysupporting

confidence: 57%

Evaluation of Gadolinium Oxide as a Blocking Layer of Charge-Trap Flash Memory Cell

Kim

et al. 2008

Electrochem. Solid-State Lett.

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“…Amorphous ZrO 2 is one of the most promising dielectrics (dielectric constant k-value ~20) to replace SiO 2 in MOSFETs at the 45-nm node CMOS technologies. Due to the aggressive down-scaling of MOSFET, higher dielectric constant materials and higher mobility semiconductors other than silicon are introduced [ 1 - 11 ]. Germanium is considered to be a good candidate to replace silicon in the channel of next-generation high-performance CMOS devices, while rare earth oxides belonging to another class of materials offer good passivation of germanium to reduce the density of interface states, as it has recently been suggested [ 5 , 7 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

Dielectric Relaxation of La-Doped Zirconia Caused by Annealing Ambient

et al. 2010

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La-doped zirconia films, deposited by ALD at 300°C, were found to be amorphous with dielectric constants (k-values) up to 19. A tetragonal or cubic phase was induced by post-deposition annealing (PDA) at 900°C in both nitrogen and air. Higher k-values (~32) were measured following PDA in air, but not after PDA in nitrogen. However, a significant dielectric relaxation was observed in the air-annealed film, and this is attributed to the formation of nano-crystallites. The relaxation behavior was modeled using the Curie–von Schweidler (CS) and Havriliak–Negami (HN) relationships. The k-value of the as-deposited films clearly shows a mixed CS and HN dependence on frequency. The CS dependence vanished after annealing in air, while the HN dependence disappeared after annealing in nitrogen.

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“…From the cross section, as expected, a multilayer of graphene was observed between the HfO 2 and the alumina layer, which was 0.4 nm thick. The aluminum oxide layer appears to be predominantly amorphous, as anticipated for films made by ALD at low deposition temperatures [19,23,24] . There were some regions, as identified in Fig.…”

mentioning

confidence: 85%

Alumina Graphene Catalytic Condenser for Programmable Solid Acids

Onn

Gathmann

Wang

et al. 2022

Preprint

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Precise control of electron density at catalyst active sites enables regulation of surface chemistry for optimal rate and selectivity to products. Here, an ultrathin catalytic film of amorphous alumina (4 nm) was integrated into a catalytic condenser device that enabled tunable electron depletion from the alumina active layer and correspondingly stronger Lewis acidity. The catalytic condenser had the following structure: amorphous alumina/graphene/HfO2 dielectric (70 nm)/p-type Si. Application of positive voltages up to +3 V between graphene and the p-type Si resulted in electrons flowing out of the alumina; positive charge accumulated in the catalyst. Temperature programmed surface reaction of thermocatalytic isopropanol dehydration to propene on the charged alumina surface revealed a shift in the propene formation peak temperature of up to ΔT(peak)~50 ⁰C relative to the uncharged film, consistent with a 16 kJ/mol (0.17 eV) reduction in the apparent activation energy. Electrical characterization of the thin amorphous alumina film by ultraviolet photoelectron spectroscopy (UPS) and scanning tunneling microscopy (STM) indicates the film is a defective semiconductor with an appreciable density of in-gap electronic states. Density functional theory calculations of isopropanol binding on the pentacoordinate aluminum active sites indicate significant binding energy changes (ΔBE) up to 60 kJ/mol (0.62 eV) for 0.125 e- depletion per active site, supporting the experimental findings. Overall, the results indicate that continuous and fast electronic control of thermocatalysis can be achieved with the catalytic condenser device.

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Tetragonal Phase Stabilization by Doping as an Enabler of Thermally Stable HfO2 based MIM and MIS Capacitors for sub 50nm Deep Trench DRAM

Cited by 22 publications

References 8 publications

Evaluation of Gadolinium Oxide as a Blocking Layer of Charge-Trap Flash Memory Cell

Evaluation of Gadolinium Oxide as a Blocking Layer of Charge-Trap Flash Memory Cell

Dielectric Relaxation of La-Doped Zirconia Caused by Annealing Ambient

Alumina Graphene Catalytic Condenser for Programmable Solid Acids

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