bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Modeling Extended Defects in Semiconductor Devices
Authors: Moroz Victor , Wong Hiu Yung , Choi Munkang 
Published: February 2020

We perform analysis of several key aspects of the extended defect formation and their impact on silicon and GaN transistors. Heterogeneous epitaxy has been an enabling technique in transistor design since 90 nm technology node. The most widely used stress engineering technique is based on introducing crystal lattice mismatch stress by growing SiGe on Si. Depending on Ge content and on the size and shape of the selectively grown SiGe islands, the lattice mismatch stress can be high enough to introduce edge dislocations and stacking faults. Once the dislocations are created, they can move, driven by stress gradients towards more energetically favorable locations. An example of creating geometrical features to attract dislocations towards certain area has been demonstrated experimentally for epitaxial SiGe layers exceeding critical thickness on non-planar Si surfaces [1]. We reproduce such behavior by numerical minimization of elastic strain energy of an ensemble of {111} stacking faults (Fig. 1).
Whenever dislocations manage to escape such herding and encroach into sensitive transistor areas, we perform quantum transport analysis to estimate the impact of a dislocation on electron scattering, on-state and off-state currents for Si nanowires with 5nm design rules.
Another area where extended defect monitoring is essential is the GaN power switches. To achieve low buffer leakage in AlGaN/GaN HEMT for high voltage applications, it has been proposed to intentionally dope the GaN buffer with carbon [2]. This creates acceptor traps in the buffer to pin the Fermi Level at ~0.86 eV above the valence band [3]. A p-type buffer is thus formed and isolated from the Two-Dimensional Electron Gas (2DEG), which aggravates current collapse [3][4]. However, experimental results show that the magnitude of current collapse is less than suggested by modeling which can be attributed to the buffer being connected to the 2DEG through threading dislocations [3]. In this work, we perform 3D TCAD analysis of the impact of threading dislocations on the buffer trapping/de-trapping and current collapse.
[1] R. Gatti, F. Boioli, M. Grydlik, M. Brehm, H. Groiss et al., Appl. Phys. Lett., 98, 121908 (2011)
[2] E. Bahat-Treidel, F. Brunner, O. Hilt et al., IEEE Trans. Electron Devices, 57(11), 3050–3058 (2010)
[3] M. J. Uren, M. Silvestri, M. Cäsar, G. A. M. Hurkx, J. A. Croon, J. Šonský, and M. Kuball, IEEE Electron Device Lett.
35(3), 327–329 (2014)
[4] M. J. Uren, J. Möreke, and M. Kuball, IEEE Trans. Electron Devices
59 (12), 3327–3333 (2012)
Fig. 1. Dislocations in epitaxial SiGe layer move towards the bottom of a V-shaped trench in Si wafer (a). Each additional dislocation reduces the total elastic strain energy of the structure (b).

Figure 1
(Invited) Mobile Ions, Transport and Redox Processes in Memristive Devices
Authors: Valov Ilia , Luebben Michael , Wedig Anja , Waser Rainer 
Published: February 2020

Redox-based resistive switching memories (ReRAM) developed rapidly in the last decade as most promising candidates for nanolelectronic industry for new type non-volatile memory devices fulfilling the demands for green IT i.e. low power consumption, high operation speed and integration density, scalability and reliability. Recent achievements have clearly demonstrated the diversity of applications these devices can be used apart from the simple memory function – for neuromorphic applications, alternative computing and logic operations, selector elements. These developments are supported by system functionalities having their origin in the electrochemical nature of the ReRAM cells.
In this talk the newest achievements in the microscopic understandings of the processes responsible for the ReRAM functionalities will be presented. It will be shown that different ions (both cations and anions) are mobile and can undergo electrochemical transformation and thus, contribute to the resistive switching. The effects of moisture will be presented and their importance for both ECM and VCM ReRAMs will be discussed. The influence of different electrode materials in terms of electrocatalytic activity and passivation behavior will be highlighted. Finally it will be shown that the nanobattery effect is fundamental and inevitable for the neuromorphic applications.
High-Performance Thin-Film Transistors Based on Highly Crystalline CVD-Grown Multilayer MoSe2 Films
Authors: Liu Na , Jung Chulseung , Moon Hyunseong , Hong Seongin , Hong Young Ki , Omkaram Inturu , Kim Sunkook 
Published: February 2020

Layered semiconductors based on transition metal dichalcogenides (TMDs) (MX2, M = Mo, W; X = S, Se, Te) exhibit many distinctive characteristics, including wide band gap (Eg > 1 eV), high carrier mobility (>100 cm2/VS), large photoresponsivity (~500 A/W), and an outstanding mechanical flexibility. Thus, the TMD materials can serve as high-performance flexible/stretchable multifunctional electronics such as field-effect transistors (FETs), photodetectors, sensors and integrated circuitries. For realizing such electronic devices, reproducible large-area production of two-dimensional TMD materials becomes a key issue.
It has been reported that MoSe2 shows a higher photoresponsivity compared to MoS2 because of the quantum confinement effect during the bad gap transition. On the other hand, multilayer TMDs provide a wider spectral response and higher photoresponsivity than monolayer TMDs. Additionally, FETs based on multilayer TMDs offer a relatively high performance, which are expected to be more suitable for commercial fabrication process than monolayer TMDs. Several groups have successfully synthesized monolayer MoSe2. However, there is hardly to find any research in chemical vapor deposition (CVD)-grown multilayer MoSe2 and its applications.
In this study, a highly crystalline multilayer MoSe2 film was grown by CVD method directly onto SiO2 substrates. Firstly, we used a relatively high pressure (>760 Torr) to form multiple nuclei during the CVD growth, resulting in multilayer MoSe2 film. The fabricated multilayer MoSe2 thin-film transistors (TFTs) exhibit ambipolar behaviors with reasonably large field-effect mobility (~10 cm2/Vs) and high photoresponsivity (93.7 A/W). Secondly, large-grain multilayer MoSe2 was synthesized using a modified CVD method. Polycrystalline compounds of MoSe2 as precursor were directly vaporized onto Mo-coated SiO2 substrates. The multilayer MoSe2 has a relatively large grain size of several hundred micrometers. Transistors based on such MoSe2 single grains show n-type characteristics with field-effect mobility up to 121 cm2/Vs and on/off current ratio higher than 104 on Si wafers or plastic polyimide films. The MoSe2 transistor on polyimide substrate even shows good mechanical flexibility while bending down to a radius of curvature as small as 5 mm. The overall results of CVD-grown multilayer MoSe2 offers high speed, highly photoresponsive transistor for high-performance flexible/stretchable electronics.
Multiple Magnetic Resonance of Nuclei in a Two-Dimensional Electron System
Authors: Qian Xuan , Ji Yang , Umansky Vladimir 
Published: February 2020

Nuclear magnetic resonance (NMR) with high sensitivity is a powerful tool to study nuclear spin physics in semiconductors. Recent progress in quantum information processing requires deep understanding of nuclear spins, which are almost ideal qubits for the manipulation and storage of the quantum information [1].Optical pumping can increase the polarization of nuclear spins in semiconductors such as GaAs by many orders of magnitude, improving the sensitivity in conventionally detected nuclear magnetic resonance experiments. Optical detection of these NMR transitions may further increase the sensitivity, allowing an all-optical NMR which is free of radio frequency fields.
Here we report all-optical NMR experiments in a GaAs/AlGaAs two-dimensional electron system. When the modulation frequency hits the frequency of a transition between nuclear levels of the different isotopes, a resonance appears in the Kerr rotation signal. Besides the fundamental resonance for frequency matching also resonances at frequencies at fractions of the fundamental frequency occur, in good accord with a simple model. Such multiple NMRs arise from interaction between modulated spins of polarized electrons and nuclear spins[2].
References
[1] D. D. Awschalom, D. Loss, and N. Samarth, Semiconductor Spintronics and Quantum Computation (Springer-Verlag, Berlin, 2002)
[2] X. Qian, et al., Phys. Rev B 93, 035302 (2016).
(Invited) Ferroelectric (Hf,Zr)O2 Films
Authors: Hwang C. S. 
Published: February 2020

Since the first report on the ferroelectricity in ultra-thin Si-doped HfO2 film [1], the unexpected ferroelectricity in doped HfO2 and (Hf,Zr)O2 solid solution films are attracting a great deal of attention from the ferroelectric community.[2] Compared to the conventional ferroelectrics based on perovskite structure, HfO2-based ferroelectrics can be extremely thin with mature deposition process such as atomic layer deposition, environmentally benign with lead-free nature, and Si-compatible.[2] Especially, the ferroelectricity and antiferroelectricity in (Hf,Zr)O2 solid solution are considered highly promising for various electronic and energy applications.[2] The ferroelectric Hf0.5Zr0.5O2 film could have remanent polarization value higher than 20 mC/cm2, and could endure more than 109 times of electric field cycling, meaning that it is a promising candidate for the future memory applications.[2] The high coercive field of ~1 MV/cm enables even 10 nm-thick films can have sufficiently large memory window.[2] The antiferroelectric Hf0.2Zr0.8O2 film could harvest 11.5 J/cm3 cycle from its pyroelectricity, and could show adiabatic temperature change of 13.4 K for solid state cooling.[3] As a electrostatic capacitor, Hf0.3Zr0.7O2 film could store 46 J/cm3 of electric energy.[4] On the other hand, the academic researches to understand this unexpected ferroelectricity is also under rapid progress. The two step polarization switching based on the involvement of intermediate nonpolar phase in Hf0.4Zr0.6O2 film was also reported, which could be understood based on the classical first order phase transition theory.[5] The so-called “wake-up” effect, which generally means the depinching of the pinched ferroelectric hysteresis in pristine state in (Hf,Zr)O2 film, is another interesting topic in this field. The wake-up effect is now ascribed to the involvement of the complicated polymorphisms in (Hf,Zr)O2 films being related with the motion of charged defects such as oxygen vacancies.[6] In this talk, the recent progresses in the ferroelectric performance of (Hf,Zr)O2 thin films will be comprehensively reviewed based on both theoretical and experimental studies.
[1] T. S. Boescke et al., Appl. Phys. Lett. 99, 102903 (2011).
[2] M. H. Park et al., Adv. Mater. 27, 1811 (2015).
[3] M. H. Park et al., Nano Energy 12, 131 (2015).
[4] M. H. Park et al., Adv. Energy Mater. 4, 1400610 (2014).
[5] M. H. Park and H. J. Kim et al., Nanoscale, DOI: 10.1039/c5nr08346j
[6] H. J. Kim et al., Nanoscale 8, 1383 (2016).
(Invited) Advanced ALD Reactor Designs
Authors: Marcus Steven Darrell , Mack Jerry , Vats Vinayak , Okuyama Yoshi , Nie Ben , Yang Lin , Song Kay , Kim Gi , Nag Somnath , Kim Eungsoo , Karim Zia 
Published: February 2020

There are many different ALD reactor designs and configurations supporting the semiconductor industry. These designs include temporal and spatial pulse/purge separation, thermal versus plasma enhanced, and single wafer versus batch reactor designs. Gas and precursor delivery designs are varied as well including cross flow versus showerhead, solid source versus liquid source, vapor draw/bubbling versus injector/vaporizer. These designs were developed based on meeting a particular film or application or process and film metric requirement (step coverage, throughput, particle performance, etc.).

The intent of this paper is to review, compare and contrast these designs and applications relative to different design combinations. The data presented will be from our AIXTRON high performance mini-batch QXP-8300. This tool is configured with a showerhead integrated with a vaporizer delivery system specifically designed for low vapor pressure precursors. A typical temporal design, QXP-8300 is a multi-wafer ALD system with a small volume confined process space. We will also be citing examples in the literature on spatial and other temporal thermal and plasma ALD configurations. An analysis of film performance and CoO comparison will also be presented.
(Invited) Using Inherent Substrate-Dependent Nucleation to Promote Metal and Metal Oxide Selective-Area Atomic Layer Deposition
Authors: Parsons Gregory N. , Kalanyan Berç , Atanasov Sarah E. , Lemaire Paul , Oldham Chris 
Published: February 2020

Substrate-dependent nucleation during CVD has been heavily studied, and several strategies for selective growth are known. Compared to CVD, atomic layer deposition generally allows more precise control over surface reactions, but to date, the most successful selective-area deposition processes are based on CVD and not ALD mechanisms.
Most ALD processes have an inherent substrate bias during nucleation, leading to problems in process development. Better understanding of this native substrate bias can be used to promote and enhance selective-area ALD. We have studied nucleation of ALD metals and dielectrics to promote native substrate bias and improve selectivity. Tungsten ALD using WF6/SiH4 onto SiO2 proceeds when surface Si-H (from SiH4) begins to form, allowing WF6 reduction to W and elimination of SiF4. We hypothesized that the introduction of a H2 or H-plasma exposure into the ALD sequence may help remove Si from the SiO2, which could extend the nucleation delay on SiO2, while not affecting W growth on Si. Using ellipsometry, XPS, high resolution SEM and in-situ quadrupole mass spectrometry we find that a H2 exposure during W ALD on ex-situ prepared SiO2 decreased the rate of W nucleation compared to growth without the H2 step, effectively increasing the selectivity window.
Also, using XPS in-situ FTIR, we explored how various oxide ALD precursors react with different surfaces. For example, doing TiO2 ALD using TiCl4 with titanium isopropoxide as the oxygen source (instead of water), we find that eliminating water slows the substrate oxidation in areas where TiO2 deposition is not desired, thereby promoting the nucleation delay to as much as 200 ALD cycles at 170°C, resulting in a maximum selectivity thickness, ts,max
≈ 2–3 nm. We will discuss other details of initial reactions obtained from in–situ infrared spectroscopy, quartz crystal microbalance, TEM, SEM, ellipsometry and other tools to better understand and improve “inherent” substrate selective ALD of metals and metal oxides.
Fabrication of p-Type La: Fe2O3 as Photocathode Via Atomic Layer Deposition
Authors: Peng Qi , Du Chun , Wen Yanwei , Shan Bin , Chen Rong 
Published: February 2020

Solar water splitting is a promising approach to develop the renewable energy. [1] Due to the excellent solution stability, earth abundance and suitable band gap, hematite is one of the most promising photoanode with n-type characteristics. [2] Nevertheless the high carrier recombination, [3] slow reaction kinetics [4] and mismatch of the band edge with the water splitting potentials [5] suppress the further promotion of its photolelectrochemical (PEC) performance. Combining with p-type material is an efficient way to tune the band structure and improve the charge carrier separation of hematite. Mg doped-hematite film with p-type characteristics was fabricated by atomic layer deposition (ALD) and significantly reduced the onset potential for photocurrent. [6] Recently, the perovskite LaFeO3 with band gap of 2.07eV are fabricated with intrinsic p-type characteristics and exhibit a high hydrogen evolution rate under visible light. [7, 8]
Here we report the fabrication of p-type La: Fe2O3 and the n-p junction of Fe2O3/La: Fe2O3 by ALD technique for its excellent conformability and controllable film growth with low defect densities. We will demonstrate the La: Fe2O3 film with p-type characteristics with Mott−Schottky plots and Hall Effect. The cathodic photocurrent as well as the PEC performance will also be discussed. By preparing the n-p junction of Fe2O3/La: Fe2O3, we design to reduce the onset potential for the photocurrent more than 100 mV comparing to the pure Fe2O3 photoanode. The incident photon-to-current conversion efficiency (IPCE) of Fe2O3/La: Fe2O3
n-p junction can be increased more than 10% at 400 nm. The PEC performance, and its mechanism will also be discussed.
References:

F. E. Osterloh, Chem. Soc. Rev., 42, 2294 (2013).

K. Sivula, F. L. Formal, M. Grätzel, Chem. Sus. Chem, 4, 432. (2011)

M. P. Dareedwards, J. Chem. Soc.
Faraday Trans. 1, 79, 2027 (1983).

K. J McDonald, K. S. Choi, Chem. Mater., 23, 1686 (2011).

J. Brillet, M. Cornuz, F. L. Formal, J. H Yum, M. Grätzel, K. Sivula, J. Mater. Res., 25, 17 (2010).

Y. Lin, Y. Xu, M. T. Mayer, Z. I. Simpson, G. McMahon, S. Zhou , D. Wang, J. Am. Chem. Soc., 134, 5508 (2012).

Q. Yu, X. G. Meng, T. Wang, P. Li, L. Q. Liu, K. Chang, G. G. Liu and J. Ye, Chem. Commun., 2015, 51, 3630.

Q. Peng, J. Wang, Y. W. Wen, B. Shan, R. Chen, RSC Adv., 6, 26192 (2016).
(Invited) Atomic Layer Deposition of Multiferroic Materials
Authors: Chang Jeffery , Pham Calvin D , Chang Jane P. 
Published: February 2020

The introduction of novel and functionally improved materials into silicon based integrated circuits is a major driver to enable the continued down-scaling of circuit density and performance enhancement in analog, logic, memory and sensing devices. Many novel materials, such as multiferroics, magnetic materials and phase change materials, are introducing new and unique functionalities that can enable continued technological advancement. The demand of engineering and precision control of these multi-functional materials such as multiferroics and their interfaces at an atomic level has grown immensely due to their versatile applications. Leveraging the self-limiting surface reactions in atomic layer deposition process, complex materials can be synthesized not only with elemental precision to achieve the desired functionality but also with outstanding conformality to ensure superior interface coupling. The latter enables the integration of ferroelectrics with ferromagnetics to realize multiferroism and magnetoelectric effect. In this talk, I will discuss current research advances in atomic layer deposition for synthesizing multifunction and complex metal oxides with tailored electronic, chemical, interfacial, thermal properties and microstructures. Specifically, I will highlight our most recent research on the engineering of multi-ferroic materials for applications in memory, antenna and motors.
Using a Peg with a Small Molecule Weight to Enhance Copper Bottom-up Filling Performance of through Silicon Via with a Deep and Wide Dimensions
Authors: Chen Po Ting , Dow Wei-Ping , Yang Ping-Feng 
Published: February 2020

Three-dimensional (3D) chip stacking has been proposed for a long time, because “More than Moore” concept has been a possible solution to overcome the limitation of gate line width of a MOS. A deep and wide TSV could be superfilled with copper electroplating within 3 houses, by adding polyethylene glycol (PEG) with a small molecular weight, mainly due to its wetting capability. The dimensions of the TSV used in this work were 50 μm diameter and 245 μm depth.
The TSVs used in this work had two types of seed layer. One was a traditional copper seed layer and the other was reduced graphene oxide (rGO) layer. Both TSVs were plated in a copper plating bath containing chloride and acidic copper sulfate as well as a suppressor, leveler and an accelerator. In addition, we added PEG with a small molecular weight. The filled TSVs were examined by cross-sectional analysis using an optical microscope (OM) and a scanning electron microscope (SEM).

Keywords

Through Silicon Via, Copper Electroplating, Reduced Graphene Oxide, 3D IC

References

[1] Wei-Ping Dow, Chih-Chan Li, Meng-Wen Lin, Ging-Wen Su, and Chen-Chia Huang “Copper Fill of Microvia Using a Thiol-Modified Cu Seed Layer and Various Levelers” Journal of The Electrochemical Society. 156(8) D314-D320 (2009).
[2] Kondo, K, Akolkar, R.N, Barkey, D.P, Yokoi, M "Copper Electrodeposition for Nanofabrication of Electronics Devices, Chapter 2 Supression Effect and Additive Chemistry" Springer, Chemistry, Electrochemistry, Nanostructure Science and Technology (2014).

Figure 1
(Invited) All-Wet TSV Fabrication Using Electroless Plated Barrier and Cu Seed Layers with Pd Nanoparticle Catalyst
Authors: Inoue Fumihiro , Shingubara Shoso 
Published: February 2020

Fabrication of TSV is one of key technologies for 3D-ICs. Filling of Cu electrode materials in a small dimension of TSV is essential for realizing fine-pitch TSVs, which reduce the lisk of thermal stress concentration issues. Cost reduction is also required to be feasible TSVs for a variety of devices. All-wet fabrication of TSVs using electroless plating of barrier and seed is one of solutions to fullfill these requirements. For realizing conformal thin barrier metal layers of Co-alloy or Ni-alloy electroless barriers in a high aspect TSV, Pd nanoparticles as catalyst are very effective because their adsorption is uniform throughout top to bottom of TSV. Furthermore they shows improvements of adhesion between dielectric and metal [1,2]. Adhesion issue is a serious obstacle for electroless plated films in general, however, we found displacement plating of Cu on electroless plated barrier layer has an excellent adhesion property. Finally, we succeeded in formation of a high aspect ratio TSV with superfilled Cu on electroless barrier/seed layers. Reliability aspects relating interdiffusion of Cu against the barrier layers will be discussed further.
[1] F.Inoue, T.Shimizu, T. Yokoyama, H. Miyake, T.Ito, H. Seki, Y.Shinozaki, T.Yamamoto,and S.Shingubara, Electrochimica Acta, 82, 372-377 (2012).

[2] F. Inoue, T. Shimizu, H. Miyake, R. Arima, T. Ito, H. Seki, Y. Shinozaki, T. Yamamoto,S.shingubara, Microelectronic Engineering, 106, 164-167 (2013).