bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of Coatings with Targeted Tunable Electrical Properties via ALD: Al2O3/ZnO and Nb2O5/Ta2O5
Authors: Brodie Alan , De Cecco Paola , Bevis Chris , Maldonado Juan R. , Bhatia Ritwik , Deguns Eric , Sundaram Ganesh M.
Published: October 2010

Conformal deposition of multi-component materials by atomic layer deposition makes it ideally suited to for use in semiconductor and MEMS devices which require precisely tuned material properties. As has been reported previously, we observe that resistivity of two component films Al2O3/ZnO and Nb2O5/Ta2O5 can be tuned to over a large range. However, we find that the electrical response of these materials change when subjected to sustained electrical field in air.
(Invited) Structural and Electrical Characterization of TiO2 and Al-Doped TiO2 Films on Ir Electrode for Next Generation DRAM Capacitor
Authors: Han Sora , Kim Seong Keun , Hwang Cheol Seong
Published: October 2010

TiO2 and Al-doped TiO2 (ATO) films were deposited at 250 oC on Ir substrates by an atomic layer deposition. The phase of the deposited film was controlled by the O3 feeding time. Rutile TiO2 films on Ir could be deposited above the O3 feeding time of 35 s. At long O3 feeding times, the TiO2 and ATO films showed excellent electrical properties (higher dielectric constant, smaller tox, and low leakage current).
Raman Spectroscopy of ZnO Thin Films by Atomic Layer Deposition
Authors: Tapily Kandabara , Gu Diefeng , Baumgart Helmut , Rigo Maria , Seo Jaetae
Published: October 2010

ZnO thin films have been deposited by atomic layer deposition (ALD) from diethyl zinc and H2O vapor. The X-ray diffraction spectra showed a c-axis preferential growth in the (002) plane. The optical vibrational properties of deposited thin films ZnO were investigated using Raman scattering spectroscopy. The ALD ZnO thin films exhibited A1 and E2 optical phonons. A blue shift was found in the Raman peaks in ALD ZnO which is indicative of a compressive stress.
The Deposition of Ru and RuO2 Films for DRAM Electrode
Authors: Schaekers Marc , Capon Boris , Detavernier Christophe , Blasco Nicolas
Published: October 2010

Ru and RuO2 films were deposited from Torus, a blend of RuO4. At low hydrogen dose RuO2 films were deposited at 200ºC. With sufficient dosing of hydrogen, Ru films were obtained; either a high enough hydrogen pressure or plasma was used. Process temperatures between 100ºC and 250ºC were explored. At 100ºC the process behaves like ALD, while at 200ºC thermal decomposition is dominating. Above 200ºC the decomposition of RuO4 increases rapidly. The deposited films are smooth and with low impurities.
Grain Size Measurement and Its Correlation to the Resistivity of Metal ALD Films
Authors: Milligan Robert B. , Li Dong
Published: October 2010

ALD deposited metal films are increasingly being employed in the semiconductor industry as CMOS gate electrodes, MIM capacitor electrodes and diffusion barrier layers. Resistivity is a critical property of these films, and is associated with factors such as the bulk resistivity of the metal, the presence of impurity atoms, and the stoichiometry of the film. At thicknesses from 2nm to 50nm electron scattering at the surface and at grain boundaries is especially important, but it has previously been difficult to decouple the grain size factor from these other factors. Grain size and orientation were measured using Scherrer's formula extracted from XRD spectra for thermal ALD TiN, PEALD TiN, ruthenium and three other proprietary metal ALD films. The dependence of grain size on deposition temperature and total film thickness has also been studied, and the resistivity of the films has been modeled using the Fuchs surface scattering model and the Mayades - Shatzkes grain-boundary electron scattering model.
ALD TaN from PDMAT in TSV Architectures
Authors: Brizé Virginie , Artaud Laurent , Berthomé Grégory , Boichot Raphaël , Daniele Stéphane , Nuta Ioana , Mantoux Arnaud , Blanquet Elisabeth
Published: October 2010

In this study, we report the TaN ALD film growth from PDMAT, in Through-Silicon Vias with NH3 as nitrogen precursor and H2 as reducing agent. We report deposits on planar and patterned substrates with high aspect ratios (5 to 20). As a reference, TaN was deposited from PDMAT and NH3 only, and the influence of H2 injections as reducing agent is reported. H2 was introduced in two manners: either during the PDMAT pulse or during the NH3 pulse. The samples obtained when H2 is introduced during the PDMAT pulse show a lower amount of oxygen than the reference deposited with only PDMAT and NH3 as precursors. Unexpectedly, when H2 is introduced during the NH3 pulse, the oxygen content increases compared to the reference. An experimental study of the deposition parameters was carried out by in situ microgravimetry to explain the H2 influence on the TaN deposition.
Interactions of Metal-Organic PEALD TaN with Ultra-Low k Dielectric Materials
Authors: Van der Straten O. , Shobha Hosadurga , Demarest J. , Maniscalco J.
Published: October 2010

Both dense and porous patterned ultra-low k (ULK) substrates have been characterized in terms of their interaction with TaN grown by plasma enhanced atomic layer deposition (PEALD). The conformal nature of the deposited TaN films by PEALD was demonstrated on a patterned dense oxide substrate. For the case of ULK dielectric materials with a dielectric constant of 2.55 (ULK2.55), penetration of TaN into the ULK matrix was observed for porous ULK2.55 while dense ULK2.55 did not exhibit any significant penetration of TaN. Both hydrogen plasma-based PEALD TaN and ammonia plasma-based PEALD TaN processes were shown to display a similar interaction with ULK2.2. A dielectric pore-sealing layer applied on patterned ULK2.2, prior to the deposition of TaN, enabled a significant reduction in PEALD TaN penetration as observed at ULK sidewalls.
(Invited) All-Solid-State Batteries: A Challenging Route towards 3D Integration
Authors: Donders Merijn , Oudenhoven Jos , Baggetto Loic , Knoops Harm , Van de Sanden M. C. M. , Kessels W. M. M. , Notten Peter
Published: October 2010

Current trends in device miniaturization and portability put strong requirements on energy storage devices with a high power to volume ratio. Li-ion all-solid-state batteries are very attractive as they combine a high storage capacity with the possibility of a flexible design and a longer lifespan than comparable battery technologies. As these storage devices approach the nano-scale, thin film conformal deposition techniques (such as PVD, (LP)CVD and ALD) become increasingly important. In this paper an outlook is given on the challenging route towards 3D integrated all-solid-state batteries and materials are suggested and discussed for each individual layer of a battery stack.
Atomic Layer Deposition of LiOH and Li2CO3 Using Lithium t-Butoxide as the Lithium Source
Authors: Cavanagh Andrew S. , Lee Younghee , Yoon Byunghoon , George Steven
Published: October 2010

Atomic layer deposition (ALD) was utilized to grow LiOH and Li2CO3 films using lithium tert-butoxide, H2O and CO2. Film growth was monitored with a quartz crystal microbalance at 225 °C. LiOH ALD had a growth rate of 12.7 ng•cm-2•cycle-1 before displaying evidence for hygroscopic behavior. Li2CO3 ALD had a growth rate of 17.1 ng•cm-2•cycle-1. The film identities were confirmed using Fourier transform infrared and X-ray photoelectron spectroscopies. Lithium-containing films are present in the solid-electrolyte interphase (SEI) on graphite anodes of Li-ion batteries. The ALD of an artificial SEI layer may limit lithium loss and improve the capacity stability during charge-discharge cycles.
(Invited) Dye-Sensitized Solar Cell Photoelectrode Fabrication and Modification by Atomic Layer Deposition
Authors: Martinson Alex
Published: October 2010

Dye-sensitized solar cells (DSSCs) are a class of photoelectrochemical devices with exceptional potential for low-cost, scalable solar energy conversion. The ~10-um-thick sintered nanoparticle film that often comprises the photoelectrode is utilized to chemically bind ~1017 chromophores with monolayer coverage. Although this ingenious architecture allows DSSCs to achieve power conversion efficiencies of 12%, it is the chief obstacle to further advances in the field. Alternative photoelectrode designs attainable by atomic layer deposition (ALD) have opened new routes to efficiency improvement. Ultra-thin interfacial layers grown by ALD have also been utilized to tailor the properties of the large, heterogeneous junction universal to DSSCs.
Dye-Sensitized Solar Cells Fabricated from Atomic Layer Deposited Photoanodes on Aerogel Scaffolds
Authors: Hess David , Mushfiq Mohammed , Dalvi Rashmi , Winter Raymond , Sampathkumaran Uma , Goswami Kisholoy , Yangaus-Gil Angel , Elam J. W.
Published: October 2010

Dye-sensitized solar cells (DSSCs) based on mesoporous, high surface area nanocrystalline titania (TiO2) exhibiting up to 11% solar energy-conversion efficiencies are promising materials for cost-effective devices. Our objective here is to realize a cost-effective fabrication technique coupled with suitable device architecture of nanostructured DSSCs to achieve high photoconversion efficiencies. Atomic layer deposition (ALD) offers an attractive synthetic route for fabricating conformal photoanode coating materials on a nanoporous scaffold. Here, we used silica aerogels processed by doctor blading as structural scaffolds on transparent conducting oxide substrates, to promote subsequent conformal growth of thin films of TiO2 and aluminum-doped zinc oxide (AZO) by ALD. The resulting interdigitated architecture of the photoanodes can facilitate fast electron transfer. Dye sensitization of the photoanodes was accomplished using di-tetrabutylammonium cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) ("N719", Dyesol, B2 dye) and assembled into photocells using liquid electrolytes. Co-sensitization with a second dye was found to increase the photon absorption and cell efficiency.
Two-Dye-Molecule-Stacked Structures on ZnO Films Formed by Liquid-Phase Molecular Layer Deposition (MLD) for Waveguide-Type Photo-Voltaic Devices
Authors: Yoshimura Tetsuzo , Watanabe Hirotaka
Published: October 2010

We propose a waveguide-type two-dye-sensitized photo-voltaic device with flat thin film semiconductors. P-type dye molecule (rose bengal (RB)) and n-type dye molecule (crystal violet (CV)) were successively deposited on n-type ZnO thin films by the liquid-phase molecular layer deposition (MLD) to form a n/p/n structure of ZnO/p-type dye/n-type dye. The photocurrent spectra were widened in the n/p/n structure, where, electrons excited in the n-type dye molecules and the p-type dye molecules are injected into ZnO with large efficiency. The guided light configuration achieved sufficient light absorption in the dye molecules to enhance the photocurrents by about one-order of magnitude.
The Structure and Ultraviolet Electroluminescence of n-ZnO-SiO2-ZnO Nanocomposite/p-GaN Heterojunction LED
Authors: Tsai Hung-Ling , Li Wei-Chih , Chen Miin-Jang , Shiojiri Makoto , Yang Jer-Ren
Published: October 2010

Ultraviolet (UV) light-emitting diodes composed of n-ZnO:Al-SiO2-ZnO nanocomposite/p-GaN:Mg heterojunction were fabricated on the c-plane sapphire substrate. TEM images clearly reveals a dispersion of high crystalline ZnO nanoparticles in the amorphous SiO2 matrix with sizes about 3~10 nm. Analyses of the Zn distribution by means of EDX and HAADF show a strongly non-uniform distribution of Zn within the SiO2 matrix. The SiO2-ZnO nanocomposite layer accomplishes a role of the current blocking layer and also causes, by its low refractive index, the increase in the light extraction efficiency from n-ZnO. With a SiO2 layer, significant UV electroluminescence from n-ZnO was achieved at a low forward-bias current of 1.8 mA. Strong UV emission arising from impact ionization in GaN, ZnO, and GaN:Mg states was also observed at reverse breakdown bias.
(Invited) The Surface Chemistry of Atomic Layer Deposition (ALD) Processes for Metal Nitride and Metal Oxide Film Growth
Authors: Bouman Menno , Zaera Francisco
Published: October 2010

The surface and gas-phase thermal chemistry of tetrakis(ethylmethylamido)titanium (TEMAT), by itself and in the presence of water, was investigated by using transmission infrared (IR) absorption spectroscopy and tandem gas chromatography-mass spectrometry (GC-MS). It was found that the uptake of TEMAT is partially self-limiting between 140 and 280 {degree sign}C, but that a CVD component from precursor decomposition does contribute to the deposition of Ti, more apparent with increasing temperatures. It was also found that decomposition of the amido ligands on the surface leads to the formation of surface species containing C=N bonds, probably imine intermediates produced by β-hydride eliminations steps. Finally, it was determined that TEMAT can thermally decompose by itself through a reductive coupling mechanism in which N,N'-diethyl-N'N'-dimethylhydrazine is formed. In contrast, addition of water to the reaction mixture promotes a competing ligand hydrogenation reaction to form ethylmethylamine instead.
(Invited) Ultra-Conformal CVD at Low Temperatures: The Role of Site Blocking and the Use of Growth Inhibitors
Authors: Abelson John R.
Published: October 2010

Chemical vapor deposition can afford conformal films with step coverage > 90% in via or trench features with aspect ratios {greater than or equal to} 30:1 when growth proceeds at a substrate temperature {less than or equal to} 300{degree sign}C under a precursor pressure > 0.1 Torr. These conditions correspond to a near-saturation of the film growth rate vs. precursor pressure, such that the reactive sticking probability is {less than or equal to} 10-5 per collision with the film surface. We model this in terms of a self site-blocking effect in which the growth surface is covered with a dynamic layer of adsorbed precursor molecules that inhibit the adsorption of impinging precursor molecules. We derive an analytical equation that relates the step coverage, growth rate, precursor pressure and substrate temperature for a given aspect ratio. For precursors that cannot achieve conformal coverage due to insufficient vapor pressure, conformal coverage can be achieved by adding an inhibitor species that completes the site blocking.
(Invited) Developments of ALD Processes: Experiments and Thermodynamic Evaluations
Authors: Blanquet Elisabeth , Nuta Ioana , Brizé Virginie , Boichot Raphaël , Mantoux Arnaud , Violet Perrine , Daniele Stéphane
Published: October 2010

The most commonly use for gaseous precursors in CVD and ALD processes are organometallic molecules. These ones are generally thermally unstable at low temperatures (100 - 300{degree sign}C) and requires an understanding of its gas-phase chemical behavior. The thermal cracking of the gaseous precursor PDMAT has been studied by Mass Spectrometry. Ta[N(CH3)2]5(g), Ta[N(CH3)2]4(g), N(CH3)2(g) together with TaO[N(CH3)2]4(g) have been found to be the main molecules observed in the vapor phase originated from the PDMAT vaporization. The thermodynamic data of the O-free molecules have been evaluated from literature and statistical calculations. Comparison between experiments and thermodynamic simulations performed at different temperatures and pressures, evidenced kinetic limitations in the decomposition processes: ligand rupture and ligand decomposition. Furthermore, the experimental gas-phase study confirms the presence of oxygen containing molecules in the PDMAT cracking gaseous phase which explains the presence of oxygen in the deposited ALD TaN films. Thermodynamic simulations were also used to evaluate the use of hydrogen addition to the process.
Growth Rate Control in ALD by Surface Functionalization: Alkyl Alcohols on Metal Oxides
Authors: Yanguas-Gil Angel , Elam J. W.
Published: October 2010

In this work we explore the effect that alkyl alcohols (ROH) have on the saturation growth rate during the ALD of metal oxides. The traditional dosing sequence for metal oxide ALD is: M/O/M/O... where M is the metal precursor and O is the oxygen source. We find that by dosing organic molecules prior to dosing the metal precursor (e.g. ROH/M/O...) we can modify the surface chemistry and control the saturation growth rate. We present results describing the effect of alkyl alcohols (R=Me, Et, iPr) using H2O as the oxygen source and the metal precursors Ti(iPr)4 and TiCl4 for TiO2 ALD, TMA for Al2O3 ALD, and DEZ for ZnO ALD. The ability to tune the saturation growth rate by modifying the surface chemistry can be of great utility for the ALD of doped materials where a homogenous distribution of dopants at a low concentration is desired. We show that this approach lowers the resistivity of Al-doped ZnO and allows the growth of low resistivity films at higher TMA/DEZ cycle ratios.
Growth Mechanism of ALD ZnO Films Investigated by Physical Characterization
Authors: Tapily Kandabara , Gu Diefeng , Baumgart Helmut
Published: October 2010

From diethyl Zinc, Zinc oxide thin films deposited by atomic layer deposition (ALD) were characterized using X-ray diffraction, atomic force microscope, energy dispersive spectroscopy and Rutherford backscattering. The as-deposited ALD ZnO films showed good stoichiometry and thickness uniformity. The ALD ZnO films exhibit a preferential growth in the (002) plane or c-plane. The ZnO samples were annealed in air, nitrogen, and O2 ambient at different temperatures.
Structural and Optical Properties of In2O3 Films Grown on (0001) Sapphire Substrates by Alternate Supply of Trimethyl-Indium and Nitrous Oxide
Authors: Su Hsin-Lun , Yen Kuo-Yi , Chi Wei-Hsu , Ni Ho-Ching , Gong Jyh-Rong
Published: October 2010

Indium oxide (In2O3) films were grown on (0001) plane sapphire substrates at 600°C by alternate supply of trimethyl-indium (TMIn) and nitrous oxide (N2O). In some cases, a low-temperature (LT) In2O3 buffer layer, 30 nm in thickness, was employed and annealed at elevated temperature before the final growth of In2O3 at 600°C. Based on the X-ray diffraction (XRD) results and the cross-section transmission electron microscopy (XTEM) and high-resolution transmission electron microscopy (HRTEM) analyses, a typical In2O3 film was found to deposit on the sapphire substrate with its (222) plane being in parallel to the (0001) plane of the substrate. However, there are twin structures inside the In2O3 film with the twin boundaries being alone {11-2} planes. Typically, In2O3 films deposited on LT-In2O3 coated substrates (In2O3/LT-In2O3 structures) exhibited an optical transmittance of ~90% in the visible spectrum.
Plasma-Enhanced ALD of TiO2 Using a Novel Cyclopentadienyl Alkylamido Precursor [Ti(CpMe)(NMe2)3] and O2 Plasma
Authors: Sarkar Anitha , Potts Stephen , Rushworth Simon , Roozeboom Fred , Van de Sanden M. C. M. , Kessels W. M. M.
Published: October 2010

Titanium oxide thin films of both amorphous and anatase morphologies have been deposited using remote plasma ALD over a wide temperature range (100-350 °C), using a novel heteroleptic alkylamido precursor Ti(CpMe)(NMe2)3. A high growth per cycle (GPC) of 0.07-0.08 nm (50 % higher than the GPC obtained with most other organometallic precursors). Films obtained were stoichiometric and of high compositional purity.
High-k Gate Stack: Improved Reliability through Process Clustering
Authors: Graoui Houda , Hung Steven C. , Kanan B. , Curtis R. , Bevan M. , Liu P. , Noori A. , Chu D. , Mcdougal B. , Ni C. N. , Chan O. , Date L. , Borniquel J. , Swenberg J. , Mahajani M.
Published: October 2010

High-k (HK) gate dielectric stack process integration is one of the most critical and challenging steps in the fabrication of CMOS. Sub-32nm targets are reached by integrating the high-k with a scaled interface layer (iL), post HK nitridation and anneal. The quality of the HK bulk material and it's interface with the iL plays a critical role in the transistor's reliability degradation. This paper investigates the reliability benefits of clustering the different HK stack process chambers on a single tool without a vacuum break. It was found that full clustering of the iL + HK + nitridation steps provides the most scalable and reliable gate stack.
Atomic Layer Deposition of LaOx and LaAlOx Thin Films Using Direct Liquid Injection of Lanthanum Sources
Authors: Senzaki Yoshi , Okuyama Yoshi , Kim Gi , Mack Jerry , Matthysse Larry , Kauschke Thomas
Published: October 2010

Two metal-organic lanthanum precursors, dissolved in organic solvents, were evaluated for ALD applications on 300mm diameter Si substrates using O3 as an oxidant - one with La-C bonds (Precursor I) and the other with La-N bonds (Precursor II). Precursor I has CVD-like behavior of growth rate increase with temperature in the susceptor temperature range between 240°C and 350°C. On the other hand, Precursor II exhibits ALD behavior with a saturated film growth rate in the susceptor temperature range between 240°C and 340°C. Excellent step coverage of over 90% of ALD La2O3 has been achieved in 40:1 aspect ratio structures using Precursor I. ALD LaAlOx films of 10nm thickness achieved a low leakage current density of <5x10-9A/cm2 at -2V and a k value of 15 (La/Al<1 by XPS).
(Invited) Ultrafast Atomic Layer Deposition of Alumina Layers for Solar Cell Passivation
Authors: Poodt Paul , Lankhorst Adriaan , Roozeboom Fred , Tiba Veronica , Spee Karel , Maas Diederik , Vermeer Ad
Published: October 2010

An ultrafast atomic layer deposition technique is presented, based on the spatial separation of the half-reactions, with which alumina layers can be deposited with deposition rates of more than 1 nm/s. The deposition rate is limited by the water half-reaction, for which a kinetic model has been developed. The alumina layers showed excellent passivation of silicon wafers for solar cell applications. Based on this concept, a high throughput ALD deposition tool is being developed towards throughputs of up to 3000 wafers/hr.
Hybrid Integration of Microwave Circuit Solenoid Inductors and AlGaN/GaN HEMTs Using an SU-8 Photosensitive Epoxy Interposer Layer
Authors: Fitch Robert C. , Kazimierczuk Marian , Gillespie James , Mattamana Aji , Orlando Pompei , Groves Kari , Quach Tony
Published: October 2010

Integration of active and passive microwave circuit components onto an inexpensive silicon substrate can be accomplished using photosensitive SU-8 epoxy as the interposer layer. This paper addresses the 3-dimensional integration of AlGaN/GaN high electron mobility transistor's (HEMT's) embedded into deep reactive ion etched (DRIE) pockets on a silicon substrate with gold-plated vias and transmission lines formed in a follow-on layer of SU-8 epoxy over the HEMT's. In addition, modeling, simulation, fabrication and testing of gold-plated, solenoid inductors embedded in SU-8 over the silicon substrate is covered. This integration process may replace variable inductance wire bond connections; with reproducible interconnects to enhance circuit design flexibility and accuracy. The solenoid inductors, whose inductance L and quality factor Q can be further optimized through the addition of ferrite or ferromagnetic cores, will help reduce the overall circuit footprint. This paper is organized into two parts: the solenoid model development and the HEMT integration process and test results.
GaN-Based LEDs with High Emission Directionality Using Photonic Crystal Structures for Sidewall Reflection and Light Extraction
Authors: Cheng Yun-Wei , Wang Szu-Chieh , Tan Jin Yi , Sun Yu-Hsuan , Yang Sheng-Chieh , Huang JianJang
Published: October 2010

GaN-based light emitting diodes with photonic crystal at the light emitting mesa and nano-hole at the periphery of the mesa using the same photonic crystal pattern are designed and fabricated. Optical properties such as luminescence-current characteristics, radiation profiles and angular spectra of the three kinds of devices (planar, photonic crystal on mesa surface, photonic crystal on mesa surface and sidewall nano-hole arrays) are considered. We demonstrate that the output power enhancement is primarily due to the photonic crystal but the effect on radiation profile is nearly omnidirectional. On the other hand, the sidewall nano-hole array contributes to the optical intensity at the surface normal direction by redirect the lateral emission of the device. By proper design of the photonic crystal pattern, high directionality and high extraction LEDs can be achieved.
Influence of Dry Etch Conditions on the Performance of Recessed Gate GaN/AlGaN HEMTs
Authors: Pletschen Wilfried , Kiefer Rudolf , Maroldt Stephan , Müller Stefan , Quay Ruediger , Mikulla Michael , Ambacher Oliver
Published: October 2010

Dry etch processes based on Cl2/SF6 have been developed to selectively remove GaN over AlGaN to fabricate recessed gate GaN/AlGaN High Electron Mobility Transistors (HEMTs). Since dry etch processes may damage the HEMT structure the influence of etch conditions on the transistor performance has been investigated using DC, RF and power measurements. Recess etch conditions resulting in bias potentials of only -64 V yield a shift in threshold voltage of 1.6 V as compared to transistors for which a low bias etch process (-24 V) was used.
Enhancement Performance of GaN-Based Light-Emitting Diodes by Modified Patterned Sapphire Surface
Authors: Lin Bo-Wen , Hsu Wen-Ching , Wu YewChung S.
Published: October 2010

The PSSs were fabricated by wet etching. Compared with the platform-PSS, the modified-PSS was still capped with a layer on the top platform after wet etching. The output power of the platform-PSS LED and modified-PSS are 27.3 mW and 29 mW, respectively, at an injection current of 20 mA. The output power of the modified-PSS LED is enhanced 6% compared with the platform-PSS. The results reveal that both electrical properties and optical properties of modified-PSS LED were improved.
Challenges to III-V Epi Growth for Increased Performance and Functionality Required in Advanced Wireless Devices
Authors: Rehder Eric , Lutz Charles , Stevens Kevin
Published: October 2010

InGaP/GaAs HBTs have been achieved via base doping and base compositional grades focused adjacent to the collector. This has been done while avoiding unacceptable increases in base sheet resistances which are typically seen with plain linear grades. Additionally, semi-ballistic launching of carriers into the base layer is shown to further enhance base electron velocity and device gain. These base grading and launching techniques enable enhanced dc gain which, among other benefits, can offset the gain killing effects of very heavily doped contact layers for advanced wireless devices.
Improving Gain Efficiency in Planar Impact Ionization Devices
Authors: Johnson Michael S. , Shuldberg Roy , Hawkins Aaron R.
Published: October 2010

The Solid-state Impact-ionization Multiplier (SIM) was designed to amplify signals from arbitrary current sources through impact ionization. A primary application is amplification of signals produced by photodiodes. Photodiodes made from any semiconductor can be wired directly to the SIM's injection node. Previous versions of the SIM suffer from non-ideal impact ionization efficiency as a result of injected carriers drifting through the device's depletion region without passing through the highest electric field regions and undergoing ionization events. Low impact ionization efficiency can lead to an increased excess noise factor, temperature sensitivity, and voltage sensitivity. This manuscript describes increasing SIM ionization efficiencies by introducing an insulator between the SIM's injection and output electrodes, effectively directing the carriers into the highest electric field. This method has shown to greatly increase the impact ionization efficiency in simulation and experimental results. Ionization efficiency improvements are demonstrated primarily through decreases in voltage sensitivity.
Heterointegration of Compound Semiconductors by Ultrathin Layer Splitting
Authors: Moutanabbir Oussama
Published: October 2010

Compound semiconductors are very attractive for a wide spectrum of applications in electronics, optoelectronics, photonics, and photovoltaics. From materials standpoint, the exploitation of the full potential of these technologies requires processes that can satisfy the two major conditions: (1) Integrability with the traditional technology of Si; and (2) Cost-effective. In this perspective, this paper presents the ion-cut process by which fine monocrystalline layers can be transferred onto foreign substrates. Bulk quality heterostructures frequently unattainable by direct epitaxial growth can be produced, which offers an additional degree of freedom in design and fabrication of hybrid devices. Ion-cut process can also be exploited to reduce the material cost by splitting several ultrathin layers from the same wafer. Materials and engineering issues as well as our current understanding of the underlying physics involved in the application of ion-cut process to cleave thin layers from III-V and III-nitride semiconductors are briefly discussed.
(Invited) Recent Advances in the Smart Cut Technology for CMOS Applications
Authors: Kononchuk Oleg , Landru Didier , Veytizou Christelle , Guiot Eric
Published: October 2010

New challenges for SOI wafer technology arise due to introduction of fully depleted CMOS architecture. Top Si layer thickness uniformity and reduced BOX thickness are the most demanding parameters. Replacement of CMP process in the Smart Cut SOI technology by high temperature annealing in inert atmosphere allows to meet wafer requirements for 22 nm technology.
(Invited) Germanium on Sapphire Technology
Authors: Gamble Harold S. , Baine Paul B. , Low Yee H. , Rainey Paul V. , Montgomery John H. , Bain M. F. , Armstrong B. Mervyn , McNeill David W. , Mitchell Neil S.
Published: October 2010

Silicon-on-sapphire (SOS) substrates have been proven to offer significant advantages in the integration of passive and active devices in RF circuits. Germanium on insulator technology is a candidate for future higher performance circuits. Thus the advantages of employing a low loss dielectric substrate other than a silicon-dioxide layer on silicon will be even greater. This paper covers the production of germanium on sapphire (GeOS) substrates by wafer bonding. The quality of the germanium back interface is studied and a tungsten self-aligned gate process MOST process has been developed. High low field mobilities of 450-500 cm2/V-s have been achieved for p-channel MOSTs produced on GeOS substrates. Thick germanium on alumina (GOAL) substrates have also been produced.
The Impact of Helium Co-Implantation on Hydrogen Induced Donor Profiles in Float Zone Silicon
Authors: Laven Johannes , Job Reinhart , Schulze Hans-Joachim , Niedernostheide Franz-Josef , Häublein Volker , Schulze Holger , Schustereder Werner , Ryssel Heiner , Frey Lothar
Published: October 2010

Doping profiles in proton and helium co-implanted and annealed n-type float zone silicon wafers are analyzed by means of spreading resistance measurements. After annealing at sufficiently high temperatures and/or long-enough duration, the hydrogen-related donor profiles known from proton implantations are significantly enhanced by the helium irradiation. The resulting profile shape exhibits a strong resemblance to the radiation damage distribution of the co-implantation. By increasing the ultimately introduced num-ber of hydrogen related donors without varying the available amount of hydrogen, it is shown that the donor profile resulting from proton implantation and annealing is limited by the defect species and the implanted hydrogen is supplied in surplus. The maximum of the additionally induced donor distribution by the he-lium implantation shows a different dependency on the fluence compared to the donor maximum induced by mere proton irradia-tion. The diffusion of protons through the irradiated layer during annealing is impacted by the He-irradiation.
Point Defects in Silicon Melt Growth from the Experimental Results
Authors: Abe Takao , Takahashi Toru
Published: October 2010

During growth of a FZ crystal and a CZ crystal, the temperature distributions from growth interface are measured by a two color thermometer on FZ crystal surface and three thermocouples in CZ bulk crystals, respectively. Both results show that the thermal gradient is the decreasing function of growth rate which is the premise of this paper. From comparison of growth interface shape variations using three different diameter crystals of both FZ and CZ, all results do not contradict with the above premise. One of the most important facts is that the increased thermal gradient region extends not only already grown region but also further grown region by pulling stop in FZ and lowering growth rate in CZ crystal. In consideration of Stefan's condition the premise above is discussed. The growing CZ crystals are detached from a melt and cooled rapidly, so that the point defects are frozen.
(Invited) Lifetime Degradation in Boron Doped Czochralski Silicon
Authors: Voronkov Vladimir V. , Falster Robert J. , Schmidt Jan , Bothe Karsten , Batunina Anna
Published: October 2010

The electron lifetime in boron-doped and oxygen-containing silicon decreases in the presence of excess electrons, and tends to some low saturated value. At lower intensity, the time scale of this process is strongly increased. The observed degradation kinetics, in a wide range of intensity, from 1 sun to 0.001 sun, is reproduced quantitatively within a simple model based on the presence of latent boron-oxygen centre (LC). Under illumination, LC captures an electron and then reconstructs into a recombination-active configuration (SRC). The forward reaction LC → SRC as well as the backward one depend on the population of charge states of LC and SRC. To account for the saturated lifetime in dependence of the light intensity, three charge states of SRC should be invoked, implying that SRC has two energy levels: a donor and an acceptor. The latter level accounts for the recombination activity of SRC.
Getter Effects in Low Oxygen and High Oxygen Czochralski Silicon Wafers
Authors: Kissinger Gudrun , Kot Dawid , Häckl Walter
Published: October 2010

Gettering of Cu and Ni in wafers with low and high concentrations of interstitial oxygen was investigated by haze tests. The RTA induced getter effects for Cu and Ni in low-oxygen and high-oxygen wafers are based on two different getter mechanisms, internal gettering by oxide precipitates and internal gettering by nanometer sized voids (noids), respectively. Both types of internal gettering contain a defect denuded zone below the surface. While gettering by noids is active immediately after RTA, efficient gettering by oxide precipitates requires a certain annealing time in order to achieve a high enough density and size of precipitates. It was found that the getter effect of noids is destroyed by annealing at temperatures ≥ 800 °C.
Minority Carrier Lifetime in Czochralski Silicon Containing Oxide Precipitates
Authors: Murphy John D. , Bothe Karsten , Olmo Massimiliano , Voronkov Vladimir V. , Falster Robert J.
Published: October 2010

Photoconductance methods were used to measure minority carrier lifetime in p-type Czochralski silicon processed under very clean conditions to contain oxide precipitates. 24 different sample types were characterised by chemical etching and transmission electron microscopy to determine the density and morphology of the precipitates. For samples processed to contain mainly unstrained precipitates, the lifetime component associated with oxide precipitates was extremely high (up to 4.5ms at an injection level corresponding to half of the doping level). The lifetime results show that rate of recombination depends upon the strain state of the precipitates. Recombination at unstrained oxide precipitates (sometimes referred to as "ninja particles") is weak, with a capture coefficient of approximately 1 x 10-7cm3s-1. Strained oxide precipitates and defects associated with them (dislocations and stacking faults) act as much stronger recombination centres with a capture coefficient of approximately 3 x 10-6cm3s-1. Recombination at strained precipitates and associated defects was found to depend mainly on their density (as opposed to size).
Niobium Contamination in Silicon
Authors: Polignano Maria Luisa , Codegoni Davide , Borionetti Gabriella , Bonoli Francesco , Brivio Jacopo , Greco Stefano , Marino Antonio , Monge Paolo , Patoprsta Ivana , Privitera Vittorio , Riva Caterina
Published: October 2010

In this paper niobium is characterized as a silicon contaminant. It is shown that niobium is a relatively slow diffuser, with an intermediate diffusivity between very slow diffusers such as molybdenum and fast diffusers such as iron. Niobium is found to be very effective as a recombination center, and in addition prone to surface segregation. In addition, niobium shows optical activation, but no thermal activation. Three deep levels are revealed in niobium contaminated silicon, plus an additional level observed in high contamination dose samples only. One of these levels is located very close to midgap, and consistently niobium was also found very effective in degrading the generation lifetime.
A DLTS Study of SiO2 and SiO2/SiNx Bi-Layer Surface Passivation of Silicon
Authors: Simoen Eddy , Gong Chun , Posthuma Niels , Van Kerschaver Emmanuel , Poortmans Jozef , Mertens Robert
Published: October 2010

Deep Level Transient Spectroscopy (DLTS) has been applied to Metal-Oxide-Semiconductor (MOS) capacitors fabricated on crystalline silicon n- and p-type substrates, with a SiO2 or a SiO2/SiNx bi-layer passivation stack, covered by an Al gate. It is shown that similar interface state distributions are obtained in both cases, from which it is concluded that the SiNx deposition does not degrade the interface. It is also shown that a rather large density of dangling bond defects is present at the Si/SiO2 interface, which is related to the absence of a post metallization forming gas annealing.
Modeling of Hydrogen Diffusion And Segregation in Amorphous Silicon During Solid Phase Epitaxy
Authors: Johnson Brett C. , Mastromatteo Massimo , De Salvador Davide , Napolitani Enrico , Carnera Alberto , McCallum Jeffrey
Published: October 2010

The diffusion and segregation of hydrogen in surface amorphous silicon layers during solid phase epitaxy (SPE) is modeled. The SPE and H concentration profiles from J. Roth et al., Mat. Res. Soc. Symp. Proc. 205, 45 (1992) are used to test H segregation and diffusion models. Excellent agreement is obtained with a trap limited diffusion model. This model has previously been found to describe the diffusion of fluorine well. The H segregation coefficient at the crystalline-amorphous interface is determined at a temperature of 606oC to be 0.064. The possible temperature dependence of the segregation coefficient and its effect on SPE are also discussed.
(Invited) Recent Insights in the Diffusion of Boron in Silicon and Germanium
Authors: Mirabella Salvo , De Salvador Davide , Bruno Elena , Napolitani Enrico , Scapellato Giorgia , Mastromatteo Massimo , Impellizzeri Giuliana , Bisognin Gabriele , Boninelli Simona , Terrasi Antonio , Carnera Alberto , Priolo Francesco
Published: October 2010

Experimental evidences and microscopic modelling of the mechanism of B diffusion in Si and Ge are given. In both the lattices B migrates by the mediation of self-interstitials (Is). In Si, B diffusion occurs mainly through the formation of a BI0 complex, after interactions of BS- with I0 or with I++ in intrinsic condition or high hole densities, respectively, followed by a proper charge exchange. A small contribution of the BI- complex is visible only under n-type doping, when BS- and I0 bind nonetheless the pairing of B with the n-dopants. Also in Ge, the B diffusion mechanism has been fixed, even if to a lower extent, revealing the need of self-interstitials to start the B motion. We evidenced the occurrence of the proton radiation enhanced diffusion (RED) and of the transient enhanced diffusion (TED) of B, modeling both the cases with the central role of Is.
Single Ion Implantation into Si-Based Devices
Authors: Johnson Brett C. , Tettamanzi Giuseppe , Yang Changyi , Alves Andew , Van Donkelaar Jessica , Thompson Samuel , Verduijn Arjan , Mol Jan A. , Wacquez Romain , Vinet Maud , Dzurak Andrew , Sanquer M. , Rogge Sven , Jamieson David
Published: October 2010

Deterministic doping is crucial for overcoming dopant number variability in present nano-scale devices and for exploiting single atom degrees of freedom. The development of determinisitic doping schemes is required. Here, two approaches to the detection of single ion impact events in Si-based devices are reviewed. The first is via specialized PiN structures where ions are directed onto a target area around which a field effect transistor can be formed. The second approach involves monitoring the drain current modulation during ion irradiation. We investigate the detection of both high energy He+ and 14 keV P+ dopants. The stopping of these ions is dominated by ionization and nuclear collisions, respectively. The optimization of the implant energy for a particular device and post-implantation processing are also briefly considered.
Combined IV and CV Analysis of Laser Annealed Carbon and Boron Implanted SiGe Epitaxial Layers
Authors: Kobayashi Daisuke , Bargallo-Gonzalez Mireia , Rosseel Erik , Hikavyy Andriy , Hirose Kazuyuki , Simoen Eddy , Claeys C.
Published: October 2010

SiGe epitaxial layers receiving sub-melt laser annealing after Carbon and Boron co-implantations are investigated. Their electrical properties have been evaluated in the reverse bias region of the IV and CV characteristics of SiGe/Si diode structures. Large dc leakage currents and frequency-dependent capacitance dispersions are observed. They are indicating the presence of electrically active defects in the studied devices. Combined IV and CV analysis suggests that the defectivity of the B-induced end-of-range defects can be enhanced by the laser treatment. This laser-driven enhancement can be suppressed by the C co-implantations. Experimental results also indicate that this C treatment is strongly affected by the laser annealing conditions.
(Invited) Impact of Stress and Defects on Advanced Junction Leakage
Authors: Moroz Victor , Choi Munkang
Published: October 2010

Comparison of relative strengths of different leakage mechanisms in stress-free vs stressed, defect-free vs full-of-defects, planar MOSFET vs FinFET is performed. First, all major junction leakage mechanisms are analyzed using numerical models in a stress-free and defect-free 30 nm planar bulk NMOSFET. Then, the impact of stress on silicon bandgap is described along with the appropriate modeling guidelines. The magnitude and the current flow patterns for different leakage mechanisms affected by mechanical stress and by crystal defects are systematically analyzed. Junction leakage increase of 30 times under 2 GPa compressive stress is expected according to both the models and the available measurements. Junction leakage increase ranges from 10 pA to 100 pA per trap depending on the particular trap location relative to the drain junction. Based on results of this analysis, suggestions are given for finding the best trade-offs in designing transistors with stress engineering and occasional defects.
(Invited) Past, Present and Future: SiGe and CMOS Transistor Scaling
Authors: Kuhn Kelin J. , Murthy Anand , Kotlyar Roza , Kuhn Markus
Published: October 2010

This paper discusses the historical role that SiGe has played in driving the CMOS scaling roadmap, including discussion of NMOS biaxial strain and PMOS uniaxial strain. The paper also discusses the potential future role that Ge or SiGe may play in CMOS scaling as a high mobility replacement for the Si channel. Challenges such as poor quality germanium oxide and the small Ge bandgap are reviewed in light of recent developments (high-k metal gate, and ultra-thin body devices) in MOSFET scaling.
(Invited) Feasibility of Ge CMOS for Beyond Si-CMOS
Authors: Toriumi Akira , Lee Choong Hyun , Nishimura Tomonori , Kita Koji , Wang Shengkai , Yoshida Mahoro , Nagashio Kosuke
Published: October 2010

To make Ge CMOS devices feasible, we need to know what determines the quality of Ge/dielectrics interface, and understand why electron mobility has so far been severely degraded in the inversion layer. In Si CMOS technology, the Si/SiO2 interface has been long investigated, and it is a strong basis even for high-k gate stack technology. In that sense, Ge/GeO2 interface should be intensively studied to make Ge gate stack possible. So, this paper mainly discusses Ge n-MOSFETs with GeO2 dielectric film.
(Invited) Beyond CMOS Devices as Enablers of Future Energy Efficient Integrated Circuits and Systems
Authors: Ionescu Adrian M. , Salvatore Giovanni A. , Lattanzio Livio
Published: October 2010

This paper presents an overview of most recent advances in energy efficient beyond CMOS devices, with particular emphasis on tunneling FETs, ferroelectric FETs and some novel hybrid devices that use combined internal mechanisms for steep switching between off and on states. Their physical mechanisms and practical limits are discussed. Such novel devices categories hold promise for future logic circuit operating at sub-0.5V voltage supply and for reducing by orders of magnitude the subthreshold power consumption. The co-integration of the steep swing switches with high performance CMOS platforms is foreseen as an enabler of novel hybrid circuit and system co-design, featuring both high performance and energy efficient modules.
(Invited) Strain Engineering and Junction Design for Tunnel Field-Effect Transistor
Authors: Yeo Yee-Chia , Han Genquan , Yang Yue , Guo Pengfei
Published: October 2010

We examine technologies aimed at performance enhancement for silicon- or germanium based TFETs, including strain engineering, source/drain junction profile engineering, and use of heterojunction materials. Device and circuit simulation results will also be discussed.
(Invited) Growth of MnGe Nanostructures for Spintronics Applications
Authors: Wang Kang , Xiu Faxian
Published: October 2010

Mainstream CMOS technology in today's electronics continues to scale down in the feature size. However, power dissipation per unit area and variability are among two major issues and challenges for the continuing scaling. Spintronics, as an emerging technology that exploits the intrinsic spin of the carriers, could potentially offer power savings, low variability and improved scalability. Using nanoscale materials makes possible heterogeneous integration of dissimilar materials by accommodation of strain and minimizing defects. In this paper, we present work on MnxGe1-x nanostructures. We discuss our nanoscale deposition and nano-epi approach in preparing single-crystalline dilute magnetic Mn0.05Ge0.95 QDs. By the use of MOS capacitor with the Mn0.05Ge0.95 QDs as the channel material and by controlling the electrical field at the gate, we demonstrate the ferromagnetism of the QDs by modulating the hole concentration in the channel. A theoretical understanding of high-Curie temperature nature of Mn0.05Ge0.95 is also provided via DOS simulations.
(Invited) Novel Electronic and Optoelectronic Devices in Germanium Integrated on Silicon
Authors: Saraswat Krishna C.
Published: October 2010

In this paper we will review recent results on heterogeneous integration of novel electronic and optoelectronic Ge grown heteroepitaxial on Si. In the past work Ge has shown much promise for high performance MOSFETs and optical detectors. In this work we will discuss several other novel devices: tunnel FET (TFET), capacitorless quantum well single transistor DRAM (1T-QW DRAM), optical modulators and light emitters for on- and off-chip optical interconnects.