bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of Copper Corrosion by Removal of H2O2 From CO2-Dissolved Water Using Palladium Catalysts
Authors: Yano Daisaku , Murayama Masami , Takahashi Masao , Kobayashi Hikaru , Yamanaka Koji
Published: October 2013

We have found that the copper dissolution rate in CO2-dissolved water (CO2 DIW) used as rinse water for wafer cleaning processes can be decreased to one-third by eliminating H2O2. DIW in semiconductor factories normally contains 10~40 μg/L H2O2, which remains also in CO2 DIW. We have developed a palladium-loaded monolithic anion exchange resin (Pd-M) as a catalyst that is able to remove H2O2 in DIW down to below 1 μg/L at extreamly high flow rate (space velocity SV = 6000 h-1), with no detectable elution of impurities.
(Invited) Wetting Behavior of Aqueous Solutions on High Aspect Ratio Nanopillars with Hydrophilic Surface Finish
Authors: Vereecke Guy , Xu XiuMei , Tsai Wei-Kang , Yang Hui , Armini Silvia , Delande Tinne , Doumen Geert , Kentie Frank , Shi Xiaoping , Simms Ihsan , Nafus Kathleen , Holsteyns Frank , Struyf Herbert , De Gendt Stefan
Published: October 2013

In semiconductor manufacturing, potential wetting issues are becoming a concern as feature dimensions are continuously scaled down and novel materials with different wetting properties are introduced in new technology nodes. The wetting behavior of silicon nanopillars with different dimensions and surface modifications has been studied using static contact angle (θ), attenuated total reflection infra-red spectroscopy (ATR-FTIR), and decoration by etching. The contact angle measurements showed a consistent deviation from the classic wetting models for patterned substrates with an hydrophilic surface termination (60°<θ < 80°). The ATR-FTIR and decoration studies gave evidence for partial wetting under these conditions, resulting from the formation of long-lasting nanobubbles. However the residual gas volumes estimated by ATR-FTIR were too small to explain the contact angle deviations. It is proposed that the apparent extension of the superhydrophobic regime to lower contact angles resulted from modifications caused by the manufacturing process to the wettability of the surface of nanopillars.
Watermark Formation Mechanism by Evaporation of Ultra-Pure Water: Study the Effect of Ambient
Authors: Tamaddon Amir-Hossein , Mertens Paul W. , Vereecke Guy , Holsteyns Frank , Doumen Geert , De Gendt Stefan , Heyns Marc
Published: October 2013

Dynamics of the evaporative drying of ultrapure water (UPW) droplets on a hydrophobic Si surface in a controlled ambient is studied. A quantitative study of the watermarks (WM) residue volume and mass is performed from low to high ambient humidity. The effects of oxygen in the gas phase and dissolved O2 concentration in UPW are investigated for different levels of ambient humidity. The shape of the drying residue on surface is studied to estimate the mechanism of residual colloids/particles deposition in presence of different ambient conditions. Our quantitative study on WM formation in different ambient humidity showed a linear increase in drying residue mass as a function of the initial UPW droplet volume.
Contamination Control in Supercritical CO2 Drying Process for Nano-Scale Memory Manufacturing
Authors: Hayashi Hidekazu , Okuchi Hisashi , Tomita Hiroshi , Ono Yoshinori , Nakamori Tadashi , Sugawara Hiroshi
Published: October 2013

The control of defects on the wafer is a critical task for nano-scale memory devices to achieve high yields. Even though supercritical CO2 drying technology has been available for more than 10 years, its application in 300mm wafer fabrication process still lacks an effective solution for the control of particles and metallic contaminant generated. To address this, the authors studied the CO2 purification process and found that most of particles on the wafer after supercritical CO2 treatment were found to be organic contaminants from the CO2 raw material. A CO2 purification system with an activated carbon absorber demonstrated superior performance for removing organic contaminants from the CO2. The metallic contaminants, coming from the supercritical chamber’s stainless steel parts, were decreased by aging of the supercritical fluid at a high temperature. A dense metal oxide film generated by aging with IPA-added supercritical CO2 at a high temperature was shown to prevent corrosion of the stainless steel surface. Knowledge and control of contaminations at the nano level will soon enable supercritical CO2 drying in 300mm nano-scale memory manufacturing.
Characterization of the Descum Process for Various Silicon Substrates Doping
Authors: Tiwari Chandra S , Lim Yong Sheng , Fulton Ralph , Srinivasan Jay , Gisinger Matt , Flynn Patrick , Mak Lai Ho
Published: October 2013

The descum process is temperature-sensitive process. It has been demonstrated that the process is very sensitive to silicon substrate doping, which impacts wafer heating. A higher doping level caused much higher resist removal when the descum process was ran in a reactor that also ran dry strip processes. The higher level of resist removal was the result of higher wafer surface temperature. The likely causes for higher wafer surface temperature are lower thermal conductivity and higher emissivity of the highly doped wafer substrate.
TiN Metal Hard Mask Removal with Selectivity to Tungsten and TiN Liner
Authors: Lippy Steven , Chen Li-Min , Peethala Brown , Rath David L , Boggs Karl , Sankarapandian Muthumanickam , Kennedy Evelyn
Published: October 2013

Low-pH titanium nitride (TiN) removal formulations utilizing oxidizers other than hydrogen peroxide (H2O2) have been developed with superior TiN selectivity toward W and the inter-level dielectric (ILD) films. One critical challenge is protecting the TiN barrier layer between the W and dielectric layer, which is often exposed during the TiN metal hard mask (MHM) removal step. This study focused on developing and optimizing formulations with TiN MHM etch rates ≥ 100 Å/min at temperatures ≤ 60oC, with compatibility toward W, ILD films, and the TiN liner. The galvanic corrosion was tailored to protect the TiN liner in the presence of W. A simple yet novel patterned wafer test vehicle was developed to facilitate this work, enabling the investigation of the chemical impact at the W/TiN liner interface.
Reliability of ALD Hf1-XZrxO2 Deposited by Intermediate Annealing or Intermediate Plasma Treatment
Authors: Bhuyian Mdnasiruddin , Misra Durga , Tapily Kandabara , Clark Robert , Consiglio Steve , Wajda Cory , Nakamura G. , Leusink Gert
Published: October 2013

The reliability of atomic layer deposited Hf1-xZrxO2 with x=0.8 on a SiON interfacial layer (IL) has been analyzed in detail for three different oxide deposition processes, (i) DADA: samples were subjected to dielectric deposition and thermal annealing in a cyclical process; (ii) DSDS: samples were subjected to similar cyclical process with dielectric deposition and exposure to Ar plasma; and (iii) As-Dep: the dielectric for the control samples was deposited without any intermediate step. Capacitance-voltage and current-voltage characteristics of the MOS capacitors (MOSCAP) with metal gate (TiN), subjected to a constant field stress of 2.75 × 107 V/cm in the gate injection mode, show that the flat-band voltage shift (∆VFB
) and stress induced leakage current (SILC) below 100 s stress is the lowest for DSDS samples whereas the worst degradation was observed for DADA samples. However, identical degradation was observed in all sample types when stress was increased to 1000 s. Intermediate plasma exposure (DSDS process) seems to supress the oxide trap formation as it provides EOT downscaling ability and good reliability performance. The reliability characteristics, when compared with pure HfO2, seem to improve with the addition of ZrO2.
Reliability of La-Silicate MOS Capacitors with Tungsten Carbide Gate Electrode for Scaled EOT
Authors: Hosoda Shuhei , Tuokedaerhan Kamale , Kakushima Kuniyuki , Kataoka Yoshinori , Nishiyama Akira , Sugii Nobuyuki , Wakabayashi Hitoshi , Tsutsui Kazuo , Natori Kenji , Iwai Hiroshi
Published: October 2013

Reliability of La-silicate gate dielectrics with tungsten carbide gate electrode have been investigated by Constant Voltage Stress (CVS) measurement. During constant voltage stress of the MOS capacitors, La-silicate MOS capacitors with tungsten carbide gate electrodes show better reliability due to the nice interface properties.
Resistivity of Ni Silicide Nanowires and Its Dependence on Ni Film Thickness Used for the Formation
Authors: Song Jinhan , Matsumoto Kazuki , Kakushima Kuniyuki , Kataoka Yoshinori , Nishiyama Akira , Sugii Nobuyuki , Wakabayashi Hitoshi , Tsutsui Kazuo , Natori Kenji , Iwai Hiroshi
Published: October 2013

Ni silicide nanowires have been formed by 2-step annealing process (2-step RTA) as SALICIDE process. All nanowires with width range from 20 to 90 nm are measured their electronic characteristic and revealed drastic increase of resistivity in less than 40 nm area. In this study, a low resistivity was obtained for a little more than 50μΩcm by controlling Ni film thickness and investigated its reason.
Advanced Spectroscopic Ellipsometry Application for Multi-Layers SiGe at 28nm Node and Beyond
Authors: Hsuan Teng-Chun , Hu Yi-Cheng , Hsu Ming Chih , Zhan Dian-Zhen , Yu Stan , Chien Chin-Cheng , Chang Shao-Ju , Chiu Sheng-Min , Huang Chien-Jen , Cheng Chao-Yu , Cheng Juli , Raphael Getin , Jiang Zhiming , Carlos Ygartua , Tan Zhengquan , Hoobler Ray
Published: October 2013

Spectroscopic Ellipsometry (SE) is a commonly used non-destructive method to perform in-line monitoring of film thicknesses and optical indexes for the semiconductor industry. SE metrology can also monitor film composition by correlating optical indexes to species concentration. Germanium concentration (Ge%) measurement after SiGe epitaxial layer is a critical application at 40/28nm nodes to evaluate strain induced in the PMOS channel;. however, for 28nm and beyond, metrology needs to monitor Ge% on more complex SiGe film processes. This paper describes accurate and stable Ge% measurement on multi-SiGe layers by using optimized optical models and multiple correlation methodologies using SE metrology and how SiGe and Si-cap thicknesses can be reported simultaneously and independently. This paper demonstrates how to create enhanced SiGe models using KLA-Tencor Off-Line Spectral Analysis software based on DoE wafers with wide range split. Five different Ge% conditions are considered and multiple correlations created to report Ge% with less than 1% absolute offset to XRD reference tool. The final measured result also shows excellent Ge% stability (STDEV ~ 0.13%) even when multi-SiGe thicknesses are changed.
(Invited) Integration of High-κ Dielectrics on Epitaxial (100), (110) and (111) Germanium for Multifunctional Devices
Authors: Hudait Mantu K , Zhu Yan , Maurya Deepam , Priya Shashank
Published: October 2013

With continued scaling of Si CMOS technology, new channel materials and device architectures are needed to address power consumption and constrained high-speed operation. With the demonstration of n-channel III-V transistors, the development of equivalent p-channel transistor is mandatory to realize energyefficient CMOS logic. The bulk transport properties of Ge make it an ideal candidate for p-channel transistor. The ultra-high hole mobility Ge can be realized through a III-V/Ge/III-V transistor configuration with different surface orientations would enable much faster switching, thus addressing dynamic power consumption, while the superior high- κ gate dielectric and larger bandgap barrier would help minimize OFF-state leakage. This paper discusses the i)
in-situ
growth of III-V/Ge/III-V heterostructure, ii) tailor-made surface orientations of Ge enable to achieve both high-hole and high-electron mobilities, and iii) band offsets of high- κ dielectrics on crystallographic oriented epitaxial (100)Ge, (110)Ge, and (111)Ge layers using solid state molecular beam epitaxy.
High Quality SiGe:B of High Ge Layer for 14nm and Beyond FINFET Processes
Authors: Liao Chin I , Chen Chun Yua , Yu Stan , Chien Chin Cheng , Yang Chan Lon , Wu J Y , Ramachandran Balasubramanian
Published: October 2013

The selective Epi of high quality with the high Ge of >50% has been demonstrated. The high quality Epi morphology can be obtained by modulating the Epi temperature to < 600C. The diamond shape Epi film with dislocation free can be observed by TEM. The flat Epi surface and the full strain Epi film can be analyzed by XRD. The Boron out-diffusion behavior in SiGe of high Ge study shows the tail abruptness was from 3nm/decade to 4nm/decade after S/D imp and anneal. The Boron out-diffusion can be well controlled by the high Ge and high quality SiGe Epi.
Interaction of Germanene with (0001)ZnSe Surfaces: A Theoretical Study
Authors: Houssa Michel , Scalise Emilio , van den Broek Bas , Pourtois Geoffrey , Afanas'ev Valery V. , Stesmans Andre
Published: October 2013

The interaction of germanene, the germanium counterpart of graphene, with (0001)ZnSe surfaces is investigated theoretically, using first-principles simulations. On a non-reconstructed (0001) ZnSe surface, germanene is predicted to be metallic, due to the pinning of the Fermi level by Se surface states. On a reconstructed (0001)ZnSe surface, which should be more energetically stable for very thin layers, the germanene layer is found to be semiconducting, with an energy band gap of about 0.4 eV. Remarkably, the nature (indirect or direct) and magnitude of this energy band gap can be controlled by an out-of-plane electric field, a semiconductor to metal transition being predicted for electric fields larger than about 0.6 V/Å.
Light Wavelength Effect on Tungsten Oxide Dielectric Properties
Authors: Lin Chi-Chou , Kuo Yue
Published: October 2013

MOS capacitors composed of the WOx high-k gate dielectric were fabricated and investigated for the electrical properties under different light exposure conditions, i.e., blue, green, and red lights, separately. The sputter deposited WOx film layer was fully oxidized after the post deposition annealing step. The leakage current was increased by light exposure due to the generation and transport of electron-hole pairs. The shorter the exposure light wavelength is, the film shows less C-V hysteresis, which is due to the more pronounced above mechanism.
FTIR-ATR Study on Near-Interface Structure of Thermal Oxides on 4H-SiC Substrates
Authors: Hirai Hirohisa , Kita Koji
Published: October 2013

Thermal oxides on 4H-SiC (0001) (Si-face) and (000-1) (C-face) grown at 1100°C were characterized by Fourier transform infrared spectroscopy attenuated total reflection method. For the films thicker than 5 nm, the structure of oxide was almost the same as that of the thermal oxide on silicon irrespective of film thickness. For the films thinner than 3 nm, structural transition regions were observed near the interface on both faces, and structural difference was clearly detected between the oxides in those transition regions on (0001) and on (000-1) faces.
Schottky Barrier Height between Erbium Silicide and Various Morphology of Si(100) Surface Changed by Alkaline Etching
Authors: Tanaka Hiroaki , Teramoto Akinobu , Sugawa Shigetoshi , Ohmi Tadahiro
Published: October 2013

Electrical and physical properties of ErSix on n-type Si(100) surfaces with an alkaline solution etching are investigated. The (111) facet of Si surface affects the SBH between ErSix and n-type Si, because the SBH depends on the surface orientation of Si. A controlling the facet of orientation is a key parameter for a reducing contact resistance for high performance MISFETs. These silicidation reactions are very important to develop the high current drivability devices.
Synthesis of MoS2 Atomic Layer using PECVD
Authors: Kim HyeongU , Ahn Chisung , Arabale Girish , Lee Changgu , Kim Taesung
Published: October 2013

Graphene has become to be the most spotlighted material because it has remarkable characteristics and advantages. Despite of these advantages, Graphene is difficult to apply to semiconductor devices because of low on/off ratio respectively with zero band-gap. However, since molybdenum disulfide (MoS2) has the band gap of 1.96 eV in bulk state as well as the similar property with graphene, it can apply to semiconductor devices. Moreover single layer of MoS2 has high mobility as 200cm2/v-1s-1 and on/off ratio over 108. MoS2 is usually synthesized by Chemical Vapor Deposition (CVD) under the relatively high temperature to get high quality property. However, the CVD method has limitation to synthesis of MoS2 on flexible plastic substrate which has a melting point about 200oC. Therefore, it is very important to characterize the MoS2 synthesis methods of low temperature. In this study, MoS2 was deposited by Plasma Enhanced CVD (PECVD) under the process temperature from 150 oC to 200 oC with Mo thin film and H2S gas precursor. Mo was deposited on SiO2/Si wafer with 1 nm thickness by e-beam evaporator firstly, and then decomposed H2S gas by plasma was used for S precursors. Synthesized MoS2 thin films at 150 oC exhibited the two characteristic MoS2 raman peaks. In this experiment, synthesis of MoS2 layer by 2 conditions and we confirmed the synthesis MoS2 by raman spectroscopy. Raman spectroscopy has been widely used to determine the number of layers, as well as material property.
Spatially Resolved Optoelectronics in Lead Sulﬁde Nanowires
Authors: Yang Yiming , Peng Xingyue , Yu Dong
Published: October 2013

Spatially resolved optoelectronic investigation can reveal important information on charge transport and recombination in field-effect transistors (FETs) incorporating single nanowires (NWs). Scanning photocurrent microscopy (SPCM) was performed on single PbS NW FETs to extract diffusion length and lifetime of minority carriers as a function of gate voltage and excitation intensity. Interestingly, we observed a reverse of the photocurrent direction in gate-depleted PbS NW FETs under high intensity illumination. We attribute this effect to the back-gate induced carrier concentration gradient.
In Situ Growth of Si Nanowires Using Transmission Electron Microscopy
Authors: Chou Yi-Chia , Wen Cheng-Yen , Reuter Mark C , Su D. , Stach Eric A. , Ross Frances M
Published: October 2013

We discuss the use of the alloy catalyst AgAu to grow silicon nanowires and Si/Ge heterojunctions. Nanoscale particles of the catalyst with compositions Ag:Au varying from 2:1 to 1:2 can be fabricated and used to form Si nanowires with high crystal quality, and SiGe interfaces that are close to atomically abrupt. In situ experiments in the TEM are essential for investigating the mechanisms of growth with these alloy catalysts. We describe the relationship between growth kinetics and catalyst state, as well as the environmental stability of the alloy catalysts.
Optimization of Cu Damascene Electrodeposition Process in ULSI for Yield and Reliability Improvement
Authors: Shao Ingrid , Cheng Tien , Findeis Paul , Kelly James , Ahmed Shafaat , Angyal Matthew , Xu Yiheng , Li B. , Tinkler J. , Lustig Naftali , Engbrecht Edward , Truong C. , Chudzik M. , Grunow S.
Published: October 2013

Cu damascene electrodeposition is widely used in the microelectronics industry. A void-free fill electrodeposition process becomes increasingly crucial with the miniaturization of feature dimensions. By optimizing plating process parameters, we demonstrated substantial yield improvement and reliability improvement by reducing voiding defects and improving plated Cu/Cu seed interface during plating. First step pulse is found to be critical for liner/seed/plated Cu interface, and filling current is found to be critical for superfilling rate. In addition, we report here that by using a partial fill partitioning method, we can detect timezero plating defects more effectively than PLY, electrical testing, or cross-section SEM after the completion of Cu plating or after CMP. It plays a critical role in optimizing the process for different technologies and different levels.
Fabrication of Metal-Nitride/Si Contacts with Low Electron Barrier Height
Authors: Yamamoto Keisuke , Asakawa Kojiro , Wang Dong , Nakashima Hiroshi
Published: October 2013

We have successfully fabricated a TiN/Si contact with low electron barrier height (ΦBN) in our previous study. In this study, we fabricated Ti, Zr, Hf, TiN, ZrN, and HfN/Si contacts using rf sputtering method and evaluated their electrical characteristics. The results of metal/Si contacts well-consisted with reported results. On the other hand, the ΦBNs of metal nitride/Si contacts were remarkably low compared with those of the metal/Si contacts, which deviate largely from the empirical relation of ΦBN versus metal work function. This is considered to be attributable to an interlayer with nitrogen atoms between the metal nitride and Si. The back-gate MOSFETs with TiN, ZrN, and HfN as source/drain were fabricated, showing the normal device operation. From the device characteristics, the off-state current and parasitic resistance were associated with ΦBN of metal nitride. We believe that these fundamental data are useful for applying metal nitride to metal/Si contacts.
(Invited) Single Electron and Single Atom CMOS Perspectives
Authors: Jehl Xavier , Sanquer Marc , Vinet Maud , Wacquez Romain
Published: October 2013

Nanowire silicon-on-insulator field effect transistors provide an ideal platform to study single electron and single atom transistors. We showed that electrons can be controlled one-by-one – up to room temperature in the smallest structures. We showed also how to control and manipulate electrons on single and coupled shallow donor atoms in these structures and reported the first coupled atom transistor ever made.
(Invited) High-Speed Operation of Si Single-Electron Transistor
Authors: Takahashi Yasuo , Takenaka Hiroto , Uchida Takafumi , Arita Masashi , Fujiwara Akira , Inokawa Hiroshi
Published: October 2013

Single-electron transistors (SETs) are expected as extremely low power devices. One of the critical issues for their application is that the operation speed is thought to be limited to be very slow due to their high tunnel resistance. We investigated the high-frequency limit of Si SET operation. The SETs were fabricated by the use of pattern-dependent oxidation method, and achieved the SETs with low tunnel resistance closed to quantum limit. And then, we employed a special rectifying effect, which occurs due to the asymmetry of Coulomb diamond, when alternating current voltage was applied to the drain terminal. By the use of the effect, rectifying characteristics of Si SETs were evaluated and revealed that there is no cutoff frequency in the rectifying effect set by the capacitance and tunneling resistance. These results indicate that the rectifying effect of AC voltage is usable beyond the THz regime.
(Invited) Dopant-Atom-Based Tunnel SOI-MOSFETs
Authors: Tabe Michiharu , Moraru Daniel , Hamid Earfan , Samanta Arup , Anh Le The , Mizuno Takeshi , Mizuta Hiroshi
Published: October 2013

Recently, the role of dopants in Si devices has been changing after a long and successful history in Si integrated circuit technology. The change can be seen as a transition from “bulk-type” dopants, with averaged potential, to “atom-type” dopants, with individual atomistic potential. Furthermore, dopant energy levels are modified by the effect of dielectric misfit with surrounding Si and the outside structure, which leads to the transformation of conventional dopants into artificial deep dopants. This effect may be significantly important for the purpose of the extension of operation temperature range of dopant-atom devices from low temperatures (<50 K) to room temperature.
(Invited) Status and Future of IC Analog Technologies
Authors: Bergemont Albert
Published: October 2013

Analog technologies play a critical role in today’s digital world, translating real-world signals like sounds, images and movements , temperature and pressure into the ones and zeros of digital processing. Without analog technology, access to the digital applications that we enjoy today would not exist. The most advanced BCD Analog processes exhibit 90-130nm features sizes but it seems to halt. Are we at the end of scaling for Analog technologies? This paper will review the state of the art analog BCD processes and highlight what are the major components (process, devices & design) required to pursue scaling. It will also cover the need (and its difficult implementation) for various embedded NVMs (costly floating gate versus new emerging universal memories) as well as the importance of emerging packaging technologies such as (e)WLP, embedded SIP and TSVs. And finally it will address the emergence of smart systems in the consumer domain that will force IC makers to gradually change their IC culture as the acquisition and merging of different skills (BCD design, Packaging, Nano/bio technologies, Sensors & Software) is coming on the horizon.
(Invited) MEMS and Photonics Module Integration into SiGe BiCMOS Technology for More than Moore Functional Diversification
Authors: Tillack Bernd , Heinemann Bernd , Kaynak Mehmet , Knoll Dieter , Lischke Stefan , Mai Andreas , Rücker Holger , Yamamoto Yuji , Zimmermann Lars
Published: October 2013

The “More Than Moore” approach is targeting on diversification by combining different technologies based on a reasonable scaling level. Here, SiGe BiCMOS technology acts as the baseline process for the integration of modules increasing the functionality and by this way enlarging the spectrum for embedded system applications. In this paper we focus on the monolithic integration approach of MEMS (micro-electro-mechanical systems) into the back-end-of-line (BEOL) of the Si process, and of optical components to combine electronics and photonics (Si Photonics).
High-Quality Hybrid-GeSn/Ge Stacked-Structures by Low-Temperature Sn Induced-Melting Growth
Authors: Kinoshita Yuki , Matsumura Ryo , Sadoh Taizoh , Nishimura Tomoaki , Miyao Masanobu
Published: October 2013

GeSn alloys are attractive materials, with a potentially major impact on next-generation device applications due to the superior electrical properties and transition to direct band gap. We investigate growth of GeSn by annealing of a-Ge/Sn/c-Ge stacked structures. This achieves liquid-phase epitaxial growth of defect-free GeSn with non-equilibrium Sn concentration (~2%) on Ge substrates by a low-temperature annealing (~600oC). The non-equilibrium Sn concentration in this GeSn layers is guaranteed thermal stability for post-annealing at 600oC for 30 min.
Atomically Flat Germanium (111) Surface by Hydrogen Annealing
Authors: Nishimura Tomonori , Kabuyanagi Shoichi , Lee Choonghyun , Yajima Takeaki , Nagashio Kosuke , Toriumi Akira
Published: October 2013

In germanium (Ge) MOSFET technology, surface planarization is a serious concern for mobility enhancement at high carrier density, reliability improvement of gate dielectrics and morphology control for non-planar FETs. In this work, (111)-oriented Ge substrates were annealed at 350-750oC in pure H2 atmosphere, and the surface structure and morphology were analyzed with atomic force microscopy. A step and terrace structure was observed on the surface after the H2 annealing above 500oC. The terrace width is controllable by the off-angle of the initial surface within 0.3o at least. The roughness root mean square (RMS) at 100 x 100 nm on single terrace is ~0.05 nm which is almost our detection limit, which implies that the single terrace on H2 annealed Ge (111) is atomically flat. Furthermore, even though the initial surface roughness RMS is intentionally increased up to 0.6 nm, atomically flat terrace structure could be obtained by the H2 annealing.
Epitaxial Growth of Heavily B-Doped Si and Ge Films on Si(100) by Low-Energy ECR Ar Plasma CVD without Substrate Heating
Authors: Abe Yusuke , Kubota Shuji , Sakuraba Masao , Murota Junichi , Sato Shigeo
Published: October 2013

By using low-energy electron-cyclotron-resonance (ECR) Ar plasma chemical vapor deposition (CVD), heavily B-doped Si and Ge films can be grown epitaxially on Si(100) even without substrate heating. It was also clarified that high carrier concentration above 1018 cm-3 in Si can be obtained by low-temperature heat treatment at as low as 200-300oC. In the case of B-doped Ge on Si(100), by introducing an 1 nm-thick undoped epitaxial Ge buffer layer, crystallinity and electrical resistivity can be improved.
Fin Doping by Hot Implant for 14nm FinFET Technology and Beyond
Authors: Wood Bingxi Sun , Khaja Fareen Adeni , Colombeau Benjamin P , Sun Shiyu , Waite Andrew , Jin Miao , Chen Hao , Chan Osbert , Thanigaivelan Thirumal , Pradhan Nilay , Gossmann Hans-Joachim L , Sharma Shashank , Chavva Venkataramana R , Cai Man-Ping , Okazaki Motoya , Munnangi Samuel Swaroop , Ni Chi-Nung , Suen Wesley , Chang Chorng-Ping , Mayur Abhilash , Variam Naushad , Brand Adam D
Published: October 2013

The transition from a planar to a FinFET device structure has changed device doping requirements. The fin sidewall doping and activation, crystallinity control of the fin, junction profile and leakage control on the fin are new challenges. With continuous scaling of FinFET technology, the narrower fins become more prone to crystallinity damage by ion implant, and lead to increases in junction leakage and fin parasitic resistance. We have introduced hot implant as a superior doping technique to room-temperature implant for arsenic source drain extension (SDE) and halo implants on vertical narrow fins. We have demonstrated for the first time that hot SDE implant on 6nm CD vertical fins produced single crystalline fins and enabled 5x improvement in fin line resistance and more than 10x reduction in junction leakage compared with a room-temperature SDE implant.
Resistive Switching Properties of SiOx/TiO2 Multi-Stack in Ti-Electrode MIM Diodes
Authors: Ohta Akio , Makihara Katsunori , Fukusima Motoki , Murakami Hideki , Higashi Seiichiro , Miyazaki Seiichi
Published: October 2013

Ti-electrode MIM diodes with SiOx/TiO2 stack structure have been fabricated on SiO2/Si substrate by RF sputtering. Chemical bonding features in MIM diodes and an influence of the SiOx/TiO2 stack structure on the resistive-switching properties have been studied by the hard X-ray photo-emission spectroscopy (XAXPES) and the current-voltage (I-V) characteristics. HAXPES analyses show a reduction reaction of SiOx with the Ti top electrode and a suppression of this reaction by a formation of a TiO2 layer at the interface between Ti electrode and SiOx layer. For SiOx/TiO2 stacked MIM diodes, a distinct bi-polar type resistive-switching of counter-clockwise rotation appears after an electro-forming process. Impacts of SiOx thickness and SiOx/TiO2 multi-stack on the switching behaviors have also been investigated. The SiOx/TiO2 double-stacked sample shows better switching behavior such as the ON/OFF ratio of 2 order and the lower operation voltages.
Reduction of Interface States Density Due to Post Oxidation with Formation of AlGeO Layer at Al2O3/Ge Interface
Authors: Shibayama Shigehisa , Kato Kimihiko , Sakashita Mitsuo , Takeuchi Wakana , Taoka Noriyuki , Nakatsuka Osamu , Zaima Shigeaki
Published: October 2013

We have investigated the correlation between interface state density (D
it) and interface structure of Al2O3/Ge with post thermal oxidation. D
it around the midgap of Ge decreases with increment of oxidation temperature and saturates at more than 500°C. It is clarified that the AlGeO formation near the Al2O3/Ge interface occurs with increase in oxidation temperature. At more than 500°C, a stable Al6Ge2O13 is formed. On the other hand, GeO2 formation which is limited by the oxygen diffusion in the Al2O3 layer mainly occurred on the Al2O3 surface. Considering that Al2O3 layer prevents the oxygen diffusion compared to GeO2 layer, decomposition of GeO2 is dominant at Al2O3/Ge interface and GeO2 should be hardly formed at Al2O3/Ge interface. Therefore, AlGeO dominantly exists near the Al2O3/Ge interface and it surely lead to reduction of D
it.
High Electron Mobility in Germanium Junctionless n-MOSFETs
Authors: Kabuyanagi Shoichi , Nishimura Tomonori , Nagashio Kosuke , Toriumi Akira
Published: October 2013

We have demonstrated the high electron mobility in Ge n-channel junction-less FETs on high-doped GeOI substrate for the first time, and have discussed its electrical properties. The on/off ratio ~105 was achieved by thinning Ge thickness down to 15 nm. Then, we considered the method to estimate the mobility in junction-less FETs by focusing on the operation principle of the device. Then, the field effect mobility in the channel was estimated to be ~800 cm2/Vsec for 32-nm-thick Ge. This is thanks to the intrinsic properties of Ge.
(Invited) In Situ Characterization of Plasma-Assisted Pt ALD on W ALD Adhesion Layers with Spectroscopic Ellipsometry
Authors: Cavanagh Andrew S. , Baker Layton , Clancey Joel W. , Yin Jun , Kongkanand Anusorn , Wagner Fredrick T. , George Steven M.
Published: October 2013

In situ spectroscopic ellipsometry (SE) was used to characterize Pt ALD nucleation on W ALD adhesion layers. In situ measurements of nucleation during plasma-assisted ALD provided rapid feedback on the effect of process variables including plasma power, plasma exposure time and the process gas mixture. Ex situ characterization with X-ray photoelectron spectroscopy and X-ray reflectivity was used to verify the SE models employed during in
situ monitoring of the nucleation of plasma-assisted Pt ALD.
Ultra Dielectrophoresis Using Atomic Layer Deposited Films: Electrothermal Analysis
Authors: Emaminejad Sam , Javanmard Mehdi , Dutton Robert W. , Davis Ronald W.
Published: October 2013

By increasing the ability to apply high ac voltages at interdigitated electrodes, and thus significantly improving the strength of negative dielectrophoresis (nDEP) force, we demonstrate a significantly enhanced electrokinetic actuation microsystem. A pinhole-free, nanometer-scale, SiO2 film was deposited on electrodes, using atomic layer deposition, as a protective layer to protect the electrodes from corrosion, when applying high ac voltages (>10 V). The electrodes were capacitively coupled to the electrolyte buffer by the application of a high frequency ac voltage signal, thus avoiding electric field degradation and the consequent reduction in DEP force due to the presence of the insulating oxide layer. Additionally, temperature profile of this high voltage system was simulated to ensure that our system is not disturbed by electrothermal effects. To illustrate an application, we used this ultra-DEP (uDEP) device to demonstrate 100% detachment of anti- IgG and IgG bound beads from the surface.
ALD-TiO2 Preparation and Characterization for Metal-Insulator-Silicon Photoelectrochemical Applications
Authors: Scheuermann Andrew G. , Lawrence John P. , Gunji Marika , Chidsey Christopher E.D. , McIntyre Paul C.
Published: October 2013

Atomic layer deposition of ultrathin TiO2 films for metal-insulator-silicon photoelectrochemical applications is accomplished in a custom built ALD chamber using the precursor tetrakis(dimethylamido)titanium (TDMAT) and water vapor co-reactant. This paper discusses the procedures used to achieve high quality, repeatable depositions for this particular application. Characterization of the ALD-TiO2 films can be performed by metal-insulator-semiconductor (MIS) structure capacitance-voltage methods. Electrochemical characterization methods are also used to determine the approximate film resistivity, photovoltage, differential resistances, and stability of an MIS device performing water splitting. This set of electrochemical measurements allows for the rapid characterization of ultrathin ALD films for MIS photoelectrochemical applications.
(Invited) Characteristics of SnSx by Atomic Layer Deposition for CIGS Solar Cells
Authors: Ham Giyul , Shin Seokyoon , Park Joohyun , Jeon Hyeongtag
Published: October 2013

Tin sulfide (SnSx=1,2) films were deposited by atomic layer deposition (ALD) using Tetrakis(dimethylamino)tin (TDMASn) and hydrogen sulfide (H2S) with different temperatures (120 to 180 °C). The crystal structure of SnSx at 140 °C is SnS2 hexagonal and that of SnSx above 160 °C is observed to have an SnS orthorhombic structure. In addition, the band gap of SnSx ALD films above 160 °C displayed ~ 1.66 eV changing sharply in comparison with ~ 2.50 eV of SnSx deposited below 140°C. This data indicates that process temperatures play an important role in the effect of SnSx deposition. Therefore, SnS2 and SnS films can be widely used as alternative materials for thin film solar.
ALD Growth of PbTe and PbSe Superlattices for Thermoelectric Applications
Authors: Zhang Kai , Ramalingom Pillai Arun Deepak , Nminibapiel David , Tangirala Madhavi , Chakravadhanula Venkata S , Kübel Christian , Baumgart Helmut , Kochergin Vladimir
Published: October 2013

For this study PbTe and PbSe thin films have been prepared on silicon substrates with native oxide by Atomic Layer Deposition (ALD) using lead (II)bis(2,2,6,6-tetramethyl-3,5-heptanedionato) (Pb(C11H19O2)2), (trimethylsilyl) telluride ((Me3Si)2Te) and bis-(triethyl silyl) selane ((Et3Si)2Se) as ALD precursors for lead, tellurium and selenium . Instead of classic layer by layer ALD growth the initial ALD nucleation of lead telluride was found to follow the Vollmer-Weber island growth model. We found a strong dependence of the nucleation process on the temperature. In this project, we present the optimized conditions for growing PbTe and PbSe thin films within the ALD process window range of 170 °C to 210 °C and discuss early nanolaminate structures. Results of various physical characterizations techniques and analysis are reported.
X-ray Characterization of PEALD versus PVD Tantalum Nitride Barrier Deposition and the Impact on Via Contact Resistance
Authors: Zhang Xunyuan , van der Straten O. , Bolom Tibor , He Ming , Maniscalco J. , Edelstein Daniel
Published: October 2013

Plasma enhanced atomic layer deposition (PEALD) of TaN demonstrated the significant benefit of lowering via resistance in back-end-of-line (BEOL) dual damascene copper interconnects with a line width of 32 nm, although PEALD TaN possessed a much higher intrinsic resistivity, approximately 2000 μΩcm, compared to physical vapor deposition (PVD) of Ta-rich TaN with a value around 250 μΩcm. The mechanism of lowering via resistance was studied by X-ray characterization techniques such as X-ray fluorescence (XRF) and X-ray reflectivity (XRR). XRF analysis indicated the nucleation rate of PEALD TaN is higher on a metal surface compared to a dielectric surface. XRR analysis revealed a smoother and damage free surface between PEALD TaN and silicon oxide, while a rougher interface was formed between PVD TaN and silicon oxide. Via resistance reduction with PEALD TaN is suggested to be related to reduced physical damage at the via bottom.
Physical, Electrical, and Reliability Characteristics of Multi-Step Deposition-Annealed HfO2 Film
Authors: Cheng Yi-Lung , Hsieh Cheng-Yang , Bo Tian-Cih , Wu Chang-Sian , Lin Jian-Run
Published: October 2013

This study compares the physical, electrical, and reliability characteristics of the high-k HfO2 film that was fabricated by a single-step and a multiple-step deposition-annealed method. After annealing at 750oC, the single-step annealed HfO2 has transformed into the polycrystalline phase, whereas the multi-step annealed HfO2 is found to remain in a nanocrystalline phase, revealing that a multi-step deposition-annealing method could greatly improve the thermal stability of the HfO2 film with respect to the grain formation process. Additionally, the density and composition of the HfO2 film are enhanced by multi-step deposition-annealing process. These changes lead to an improvement in the electrical characteristics, breakdown voltage, and reliability for the multi-step deposition-annealed HfO2 film, revealing that the multi-step deposition-annealing method is a promising means for improving the thermal stability and reliability of HfO2 gate stacks.
Nano-Ordering of Donor-Acceptor Interactions Using Metal-Organic Frameworks as Scaffolds
Authors: Leong Kirsty , Foster Michael E. , Wong Bryan M. , Spoerke Erik D. , Gough Dara , Deaton Joseph C. , Allendorf Mark D
Published: October 2013

Metal-Organic Frameworks (MOFs) are nanoporous materials with tunable pore sizes that can accommodate and stabilize small molecules. Because of their long-range order and well-understood pore environment, the nano-confinement of donor-acceptor materials within MOFs offers a new methodology for creating uniform phase-segregated donor-acceptor interfaces. Phase segregation and the photo-physical effects of confining α,ω-Dihexylsexithiophene (DH-6T) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in several MOFs and the potential role of the MOF in creating a nano-heterojunction for organic photovoltaics are discussed. We demonstrate infiltration of both molecules into MOF pores and use luminescence and absorption spectroscopies to characterize the MOF-guest energy transfer processes. Comparison with density functional theory allows us to determine the energetics and band alignment within the MOF. The results demonstrate the utility of MOFs as scaffolds for sub-nanoscale ordering of donor and acceptor species within a highly uniform environment, allowing both the interaction and separation distance to be much more controlled than in the classical bulk heterojunction.
Highly Conductive PEDOT: PSS Electrode Treated with Polyethylene Glycol for ITO-Free Polymer Solar Cells
Authors: Mengistie Desalegn Alemu , Wang Pen-Cheng , Chu Chih-Wei
Published: October 2013

We used polyethylene glycol (PEG) and enhanced the conductivity of PEDOT:PSS from 0.3 S cm-1 to 805 S cm-1 with only 2% PEG additive. The conductivity was further enhanced to 1100 S cm-1 by combining PEG and methanol treatment. PEG treated PEDOT:PSS films showed better phase separation between PEDOT and PSS with fiber like 3D PEDOT networks. The carrier concentration increased by three orders of magnitude after PEG treatment. ITO-free polymer solar cells with PEG treated PEDOT:PSS anodes were fabricated and optimized. Double layer PEDOT:PSS treated with 2% PEG200 anodes showed power conversion efficiency of 3.71% while and the ITO counterpart showed 3.73%.
Semi Transparent Electrode of Au Nano Mesh on Flexible Substrates Fabricated by Transfer Printing Using Self-Organized Porous Polymer Mold
Authors: Yanagi Yuichiro , Saito Hirofumi , Fujii Shunjiro , Okukawa Takanori , Yoshida Akira , Yanagidate Tatsuki , Ohzeki Masaya , Arai Yuki , Ohori Yurina , Kaneto Daichi , Nagata Ryo , Kataura Hiromichi , Nishioka Yasushiro
Published: October 2013

In this paper, novel fabrication processes for flexible, semi-transparent, and nano-meshed Au electrodes on polyethylene terephthalate (PET) substrate utilizing transfer printing from self-organized polymer mold are described. A polycarbonate mold with honeycomb meshed structures was fabricated by a solvent casting method to form self-organized arrays of water bubbles and by drying the water bubbles. It was succeeded to transfer Au electrodes on PEDOT:PSS coated PET substrates using the Au-coated mold under the pressure of 1 MPa at 100 oC for 10 min. The transferred Au mesh has a line-width of 350 nm, a period of 1.5 μm, and a depth of 1.75 μm. The measured transmittance of Au mesh electrode was 34%, and it was less than half of that of an ITO electrode on PET substrate (75%) at photon wave length of 500 nm. However, the measured sheet resistance of the Au mesh electrode is 3 Ω/□, and it was 11 times lower than that of the ITO (33 Ω/□).
Electrodeposition and Characterization of Hematite Films Obtained from DMSO Solution
Authors: Riveros Gonzalo , Ramírez Daniel Luis , Dalchiele Enrique A. , Marotti Ricardo , Peter Laurie M. , Grez Paula , Martín Francisco , Ramos-Barrado José-Ramón
Published: October 2013

The present study shows the results obtained in the electrodeposition of hematite thin films from DMSO solution employing FeCl3 and molecular oxygen as precursors. The films were obtained through a potential cycling program at different cathodic limits and at different electrolytic bath temperatures. In all cases, as-grown films were amorphous and photoelectrochemically inactive. An annealing procedure is necessary to completely transform the electrodeposited iron oxide to a-Fe2O3 phase. XRD analyses confirm the presence of diffraction peaks corresponding to hematite after annealing, showing a strong preferential orientation of the [110] axis vertical to the substrate. Different techniques (XRD techniques, XPS analyses, SEM images, UV-Vis spectroscopy, Mott-Schottky plots and photocurrent – potential curves) have been employed in order to characterize the films and determinate their properties according with the conditions of electrodeposition and the annealing temperature.
High Efficient Inverted Polymer Solar Cells by Surface Treatment of Zinc Oxide
Authors: Woo Sungho , Kim Wookhyun , Lyu Hong-Kun
Published: October 2013

In this work, we report on the enhanced power conversion efficiency (PCE) of inverted polymer solar cells (I-PSCs) that use a surface treatment of ZnO electron transporting layer by benzoic acid derivatives. A thin SAM layers of 4-methoxybenzoic acid (mBA) or 4'-methoxybiphenyl-4-carboxylic acid (mBPCA), prepared by spin-coating, on top of ZnO, was used to induce a surface dipole at the ZnO resulted in decrease of series resistance and finally simultaneous enhancements of the short-circuit current density and fill factor. The PCE of I-PSCs based on mBA and mBPCA treated ZnO reaches 6.74 and 7.11%, respectively, while the PCE of the device based on untreated ZnO is 6.52% for PTB7:PC71BM based bulk-heterojunction active layer systems. Our results provide a promising approach to improve the performance of highly efficient inverted polymer solar cells.
Physical Biology in Cancer. 2. The physical biology of circulating tumor cells
Authors: Phillips Kevin G. , Kuhn Peter , McCarty Owen J. T.
Published: October 2013

The identification, isolation, and characterization of circulating tumor cells (CTCs) promises to enhance our understanding of the evolution of cancer in humans. CTCs provide a window into the hematogenous, or “fluid phase,” of cancer, underlying the metastatic transition in which a locally contained tumor spreads to other locations in the body through the bloodstream. With the development of sensitive and specific CTC identification and isolation methodologies, the role of CTCs in clinical diagnostics, disease surveillance, and the physical basis of metastasis continues to be established. This review focuses on the quantification of the basic biophysical properties of CTCs and the use of these metrics to understand the hematogenous dissemination of these enigmatic cells.