bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms for Interstitial-Mediated Transient Enhanced Diffusion of N-type Dopants
Authors: Harrison Scott Anthony , Edgar Thomas F. , Hwang Gyeong S. 
Published: April 2011

AbstractAs silicon transistor dimensions scale down, transient enhanced diffusion of n-type dopants has become a major barrier toward achieving required junction depths for transistors. In this paper, we use density functional calculations to identify a pathway by which silicon interstitials can mediate As and P diffusion. We show that As-silicon interstitial and P-silicon interstitial pairs in the neutral and negative charge states diffuse via a mechanism in which the dopant is bond-centered at energy minima and threefold coordinated at the high energy saddle point during dopant migration. For both As-silicon interstitial and P-silicon interstitial pairs, we conclude that the neutral pairs will dominate under intrinsic conditions while the neutral and negatively charged pairs will both contribute under heavily doped extrinsic conditions.
Ab-Initio Study of Boron Diffusion Retardation in Si1-xGex
Authors: Kim Yonghyun , Kirichenko Taras A. , Banerjee Sanjay K. , Hwang Gyeong S. 
Published: April 2011

AbstractWe study B diffusion in the presence of Ge by using a first principles density functional theory calculation. We investigate the relative stability and migration barriers of Si and Ge interstitials as well as binding energy and diffusion pathway of Boron-Interstitial (BI) pair comprised of Boron and Si or Ge interstitials. We find that Ge interstitials are more stable but less mobile compared to Si interstitials, leading to higher population of interstitials in the implanted Si1-xGex. However, BI pair comprised of Ge interstitial and Boron is less stable compared to Si interstitial –Boron pair and migration barrier of BI pair in presence of Ge is increased, leading to less TED.
Thermally Induced Deformation and Stresses During Millisecond Flash Lamp Annealing
Authors: Smith Mark , Seffen Keith A. , McMahon Richard A. , Anwand Wolfgang , Skorupa Wolgang 
Published: April 2011

AbstractA flash lamp has been proposed for annealing wafers with diameters approaching 100 mm. The equipment applies a pulse, with duration 0.5 ms to 20 ms, resulting in large transient thermal gradients in the wafer. In this paper, we present a model for the thermal reaction of this process and its effect upon the mechanical behaviour, in order to predict stresses, shape changes and to capture practical phenomenon, such as bifurcation of deformation modes. We then use the model to follow changes in the expected response consequent on altering process conditions, as well as exploring important issues associated with scaling to large wafer sizes. The model is further used to predict material yielding leading to permanent deformations. This work presents the first description of the thermo-mechanical response of wafers to flash lamp annealing in the millisecond time regime and is therefore fundamental to the use of this technique in the fabrication of semiconductor devices.
Analysis and Optimisation of New Implantation and Activation Mechanisms in Ultra Shallow Junction Implants using Scanning Spreading Resistance Microscopy (SSRM)
Authors: Eyben Pierre , Severi Simone , Duffy Ray , Pawlak Bartek , Augendre Emmanuel , Vandervorst Wilfried 
Published: April 2011

AbstractWithin this paper we have demonstrated the unique capability of scanning spreading resistance microscopy (SSRM) in order to evaluate and optimize the recent approaches towards the formation of advanced p-MOS devices. As shown in this paper, such an optimization requires a detailed 2D-analysis on completely processed devices as two-dimensional interactions may cause (unexpected) lateral diffusion and (de) activation of underlying profiles. Emphasis will be on junction formation using Ge- pre-amorphization and carbon based cocktail implantation coupled with activation based on solid phase epitaxial regrowth and/or millisecond laser anneal. In the case of a Ge-pre-amorphization implant followed by solid phase epitaxial regrowth, SSRM shows an obvious relationship between the presence of defects in the end of range region and halo implant de-activation. Based on the quantified 2D-profiles we can extract the lateral and vertical junction depths as well as the lateral and vertical abruptness of the extension region. A drastic reduction of the lateral diffusion for the cocktail implant versus the standard reference devices with classical spike annealing is eminent. At the same an important reduction of the lateral diffusion of the source/drain implants (HDD) under the spacer can be seen. The SSRM results also highlight the impact of different activation mechanisms on the channel implants (in particular on the shape of the halo pockets).
Systematic Characterization of Pseudomorphic (110) Intrinsic SiGe Epitaxial Films for Hybrid Orientation Technology with Embedded SiGe Source/Drain
Authors: Ouyang Christine , Madan Anita , Klymko Nancy , Li Jinghong , Murphy Richard , Wildman Horatio , Davis Robert , Murray Conal , Holt Judson , Panda Siddhartha , Ieong Meikei , Sung Chun-Yung 
Published: April 2011

AbstractPFET devices fabricated using embedded SiGe source/drain on (110) silicon substrates have shown significant performance improvement compared to PFETs with embedded SiGe on (100) SOI substrates. In this paper, we report a systematic material characterization on the epitaxial SiGe films, both on blanket and patterned substrates, and corresponding PFET performance data. The SiGe films were deposited in an RTCVD system. The epitaxial growth rate on (110) substrates was 30% lower than on (100), and 30% higher on patterned device wafers compared to blanket wafers. Films were characterized using an array of methods such as High Resolution XRD (for Ge composition, strain and thickness), Auger (for Ge composition), UV Raman microprobe (for strain), AFM (for surface morphology), and TEM (for epi quality). The Ge compositions determined by XRD and Auger are in excellent agreement (15~16%). The amount of strain extracted from the Raman measurements is also consistent with the amount determined by XRD, which is 0.60%, corresponding to a fully strained Si0.85Ge0.15 film. AFM showed much higher RMS and Rmax for the SiGe films on (110) substrates compared to those on (100) substrates. XTEM showed high crystalline quality with very low defect count in the SiGe source/drain and Si channel regions. PFETs with an embedded Si0.85Ge0.15 source/drain on hybrid orientation (HOT) substrates provided a 30% advantage in drive current and a 23% enhancement in ring oscillator speed compared to control devices on (100) SOI wafer.
Impact of Heavy Boron Doping and Nickel Germanosilicide Contacts on Biaxial Compressive Strain in Pseudomorphic Silicon-Germanium Alloys on Silicon
Authors: Chopra Saurabh , Ozturk Mehmet C , Misra Veena , McGuire Kris , McNeil Laurie 
Published: April 2011

AbstractIn recent years, the semiconductor industry has increasingly relied on strain as a performance enhancer for both n and p-MOSFETs. For p-MOSFETs, selectively grown SiGe alloys in recessed source/ drain regions are used to induce uniaxial compressive strain in the channel. In order to induce compressive strain effectively using this technology, a number of parameters including recess depth, SiGe thickness (junction thickness), sidewall thickness, dopant density, dislocation density, and contact materials have to be optimized. In this work, we have studied the effects of heavy boron doping and self-aligned germanosilicide formation on local strain. Raman spectroscopy has been used to study the impact of heavy boron doping on compressive stress in SiGe films. Strain energy calculations have been performed based on Vegard's law for ternary alloys and the effect of boron on strain in SiGeB alloys modeled quantitatively. It will be shown that, owing to the smaller size of a boron atom, one substitutional boron atom compensates the strain due to 6.9 germanium atoms in the SiGeB film grown pseudomorphically on silicon. The critical thickness of SiGeB has been calculated for the first time based on kinetically limited critical thickness calculations for metastable SiGe films. It will be shown that the critical thickness of the alloy increases as the boron content in the alloy is increased, making boron concentration an additional parameter for optimizing strain in the MOSFET. Based on these conclusions, boron concentration can be used to preserve the strain for thicker SiGeB films (compared to SiGe films) while keeping the dislocation density low. Furthermore, we show that NiSiGe contacts can have a profound impact on the SiGe strain. Our results indicate that NiSiGe introduces additional stress in the underlying SiGe, which further affects the strain induced in the channel
Using Quantitative TEM Analysis of Implant Damage to Study Surface Recombination Velocity in Silicon
Authors: Gasky Jennifer Lee , Morghem Sophya , Jones Kevin 
Published: April 2011

AbstractSilicon wafers with shallow trench isolation structures 3700Å deep were self-implanted with silicon at 40keV, and a dose of 1E15/cm2. This produced an amorphous layer 1000Å deep. The samples were subsequently annealed at temperatures ranging from 750°C to 900°C. The excess interstitials can recombine at the “surface” created by the proximity to the trench sidewall. Plan-view TEM was used to quantify the dislocation distribution as a function of distance from the trench sidewall. It was found that there was no measurable change in defect density as a function of distance from the trench. This was true for both the 20 minute isochronal anneal, and the isothermal study 750°C. This suggests there is a relatively weak recombination of interstitials at the surface. This is surprising given most of the TCAD models assume a very fast surface recombination velocity.
Predictive Model for B Diffusion in Strained SiGe Based on Atomistic Calculations
Authors: Ahn Chihak , Song Jakyoung , Dunham Scott T 
Published: April 2011

AbstractUsing an extensive series of first principles calculations, we have developed general models for the change in energy of boron migration state via interstitial mechanism as a function of local alloy configuration. The model is based on consideration of both global strain compensation as well as local effects due to nearby arrangement of Ge atoms. We have performed KLMC (Kinetic Lattice Monte Carlo) simulations based on change in migration energy to explain the reduced B diffusion in strained SiGe and compared our results to experimental observations. These models include significant effects due to both global stress and local chemical effects, and accurately predict the B diffusivity measured experimentally in strained SiGe on Si as a function of Ge content.
TCAD Modeling and Simulation of Sub-100nm Gate Length Silicon and GaN based SOI MOSFETs
Authors: Ma Lei , Jin Yawei , Zeng Chang , Dandu Krishnanshu , Johnson Mark , Barlage Doug William 
Published: April 2011

AbstractSub-100nm gate length silicon and GaN based SOI n-type MOSFET are modeled and simulated using ISE-TCAD (now synopsys_sentaurus). Several silicon SOI structures such as planar fully depleted SOI, FinFET, Tri-Gate MOSFET, cylindrical channel (OMFET) and triangular channel MOSFETs have been studied to compare the structure dependence of the device performance. Silicon and GaN as channel materials are also compared for these different SOI structures for projecting the device performance for very short channel SOI MOSFETs. Our study shows that for sub-100nm gate length, GaN based transistors have better Ion/Ioff ratio and higher small signal transconductance than silicon based transistors. And GaN and Si based devices have comparable performance such as sub-threshold slope and threshold roll off, etc. However for sub 20nm gate length, simulation shows that while it is not satisfying for silicon based device for digital applications, GaN based transistors with lower off state leakage current, less short channel effect than Silicon based transistors are still good candidates for digital applications . The TCAD study shows that GaN could be a promising candidate for making very short channel device as the GaN processing technology is advancing.
Film Characterization of Ultra Low-k Dielectrics Modified by UV Curing with Different Wavelength Bands
Authors: Matsuura Masazumi , Goto Kinya , Miura Noriko , Hashii Shinobu , Asai Koyu 
Published: April 2011

AbstractThis paper describes film characterization of Ultra Low-k (ULK) dielectrics modified by UV curing with different wavelength bands. We have demonstrated UV hardening of ULK-SiOC (k=2.65) with two types of UV bulbs (UV-X and UV-Y) and the UV modifications of ULK-SiOC film properties are characterized by using FT-IR spectroscopy, 29Si Solid-state NMR spectroscopy and Raman spectroscopy. FT-IR and NMR analyses reveal that UV-Y curing is preferable for UV curing modification of ULK-SiOC. UV-Y curing increases Q mode peak in NMR, resulting in the enhanced Si-O crosslinking, while UV-X curing increases TH mode and TOR mode peaks. Spin lattice relaxation time T1 for 29Si is decreased with UV curing. This result indicates that UV curing enhances molecular motion in Si-O network. Raman analysis shows that UV curing increases amorphous carbon groups, which corresponds to the enhanced molecular motion in Si-O network.
Critical and Sub-critical Debonding in Nano-clustering Porous Low-k Films
Authors: Smith Ryan Scott , Uchibori C. J. , Ho P. S. , Nakamura T. 
Published: April 2011

AbstractVery few porous low-k dielectric materials meet the basic requirements for integration into the back end of the line (BEOL) metallization. According to the International Technology Roadmap for Semiconductors, 2005, candidates for the 45 nm node need a k<2.2 and a minimum adhesion strength of 5 J/m2. Recently, a low-k dielectric material was developed, called nano-clustered silica (NCS). It is a spin-on glass with k<2.3. NCS is constitutively porous, with a micro- and mesopore size of ~2.8 nm. The first reported adhesion strength of this material was 10+ J/m2. We investigated the nature of the adhesive strength of NCS by critical and sub-critical fracture and Fourier Transform IR Spectroscopy (FTIR). The four-point bend technique and a mixed-mode double cantilever beam technique were employed. The sub-critical crack growth studies were performed in humid environments and ambient temperatures. Different post-treatments were used on NCS to achieve different molecular structure, as measured with FTIR. A correlation between molecular structure and critical adhesion energy was found. Atomistic parameters were calculated from the sub-critical crack growth data. A dependency of fracture behavior on post-treatment and, therefore, structure was observed.
Thermal and Dielectric Stability of Parylene X
Authors: Senkevich Jay J. , Carrow Brad , Wang Pei-I 
Published: April 2011

AbstractIntegrating pore sealing and barrier dielectric materials into back-end-of-the-line (BEOL) structures is challenging due to the requirements of high thermal stability, electrical stability (high breakdown, low leakage, and low dielectric constant), and barrier-like properties of the films. With Al etch-back metallization the dielectric needed to be stable to 450 °C due to Al reflow but now the thermal budget is shrinking with Cu metallization. Now the limiting factors are solder and ultra-low k (ULK) dielectric cure temperatures. These temperatures may still require thermal anneals exceeding 400 °C, which is very demanding on organic-based systems. Parylene X, a pore sealing chemical vapor depositable polymer, is deposited a room temperature via a precursor that allows the polymer to be self-initiated and without any by-products. The deposition platform allows controlled penetration of the organic polymer that allows significant fracture toughness improvement for the ULK dielectric. The polymer starts to cross-link at 175 °C with full conversion by 380 °C as measured by FT-IR spectroscopy. The polymer is shown to be stable to 420 °C with a dielectric constant of 2.7 and a leakage current of 0.5 × 10-9 A/cm2 at 0.67 MV/cm using MIMCAP structures. Parylene × was shown to have barrier-like properties in contact with both Ta and Cu metallization using bias-temperature stress (BTS) measurements at 0.5 MV/cm and 150 °C. In a Cu/Ta/parylene X/ULK dielectric stack, Ta a carbide former, can be used as an adhesive layer linking Cu to parylene × or the organic-based surface since parylene × has barrier-like properties.
PECVD Versus Spin-on to Perform Porous ULK for Advanced Interconnects: Chemical Composition, Porosity and Mechanical Behavior
Authors: Jousseaume Vincent , Le Cornec Charles , Ciaramella Frederic , Favennec Laurent , Zenasni Aziz , Simon Gurvan , Simon Jean Paul , Gerbaud Guillaume , Passemard Gerard 
Published: April 2011

AbstractPorosity introduction in a-SiOCH matrix is a main research field in microelectronic. Two techniques are used to deposit these dielectric thin films: spin-on or Plasma Enhanced Chemical Vapor Deposition (PECVD). In this work, different porous a-SiOCH thin films (k close to 2.2 – 2.3) are studied. Several synthesis ways are used to deposit these a-SiOCH layers: by porogen approach, self assembling or nanoclustering techniques for spin-on, and using a porogen approach for PECVD. Impact of deposition process and curing on material crosslinking are investigated. The skeleton structure is correlated to the elastic properties whatever the deposition technique used. Finally, porosity and pore interconnectivity are studied and the results show that barrier diffusion is less pronounced in case of small pores size such as those obtained by PECVD.
Real Time Study of Cu Diffusion through a Ru Thin Film by Photoemission Electron Microscopy (PEEM)
Authors: Hess Wayne P. , Xiong Gang , Sun Y.-M. , Joly Alan G. , Beck Kenneth M. , White J. M. , Hess Wayne P. 
Published: April 2011

AbstractWe demonstrate the efficacy of Photoemission Electron Microscopy (PEEM) as a tool to detect metal diffusion processes at nanoscale spatial resolution in real time. For a sample comprising a nominally 1 nm physical vapor-deposited (PVD) Ru thin film covering a thick Cu substrate, we have observed the appearance of bright features on a dark background as the temperature is monotonically increased and irradiated with photons from a Hg arc lamp. These bright features are the result of a lower work function due to Cu diffusion through the Ru film.
Electromigration-Induced Plastic Deformation in Cu Damascene Interconnect Lines as Revealed by Synchrotron X-Ray Microdiffraction
Authors: Budiman Arief , Tamura N. , Valek B. C. , Gadre K. , Maiz J. , Spolenak R. , Patel J. R. , Nix W. D. 
Published: April 2011

AbstractThe Scanning X-Ray Submicron Diffraction (μ-SXRD) technique using focused synchrotron radiation white beam developed in the Beamline 7.3.3 at the ALS Berkeley Lab has been used to study the microstructural evolution at granular level of Cu polycrystalline lines during electromigration. Plastic deformation was observed in damascene Cu interconnect test structures during this in situ electromigration experiment and before the onset of visible microstructural damage (voiding, hillock formation). We show here that the extent of this electromigration-induced plasticity is dependent on the line width. In wide lines, plastic deformation manifests itself as grain bending and the formation of subgrain structures, while only grain rotation is observed in the narrower lines. The analysis of the Laue reflections allow for the determination of the geometrically necessary dislocation density in individual grains as well as for the misorientation angles between small angle boundaries generated by polygonization. The deformation geometry leads us to conclude that dislocations introduced by plastic flow lie predominantly in the direction of electron flow and may provide additional easy paths for the transport of point defects. Furthermore, we observe that the rotation axis of this plastic deformation coincides with one of the <112> line directions of the known slip systems for FCC crystal, and that it is always very close (within a few degrees) to the direction of the electron flow. This finding suggests a correlation of the proximity of certain <112> line directions to the direction of electron flow with the occurrence of plastic behavior. One important practical implication of this particular finding is that the grain texture of the line might thus play an important role in giving higher resistance towards early plastic response of the Cu line upon the electromigration loading.
Effect of Cu Migration in a Field Induced Dielectric Failure
Authors: Hwang Sang-Soo , Jung Sung-Yup , Joo Young-Chang 
Published: April 2011

AbstractFor the study of dielectric failures by Cu migration, TDDB (time dependent dielectric breakdown) and 1-D FDM simulation was carried out. We tested TDDB using a simple MIS structure with no barrier Cu electrode. From our TDDB results, the TTF's in the acceleration condition and the characteristic parameter of TDDB were obtained. In the simulation parts, 1-D FDM simulation was accomplished considering space charge effect due to Cu ions.The objective of TDDB is to predict of TTF (time to failure) in the service condition form the results of an accelerating condition. The characteristic of TTF's follows E model in the accelerating condition, in the service condition, the deviation from E model was observed. This different characteristic of TTF can be explained by the mechanism of Cu migration enhanced by an applied E field. Our simulation and TDDB results reveal that the deviation from E model does not mean the change of failure mechanism, but it shows the characteristics of Cu migration.
Electrical Resistance Anomalies During Electromigration Testing of Cu Conductor Lines: Examples of Local Melting?
Authors: Zhang Hongqing , Wang Gan , Cargill III G. S. 
Published: April 2011

AbstractWe have observed abrupt, reversible resistance changes during electromigration (EM) testing of 0.16μm thick, 100μm long damascene Cu conductor lines with TaN liners and W vias. Lines of 0.2μm, 0.8μm and 2μm widths were tested and compared. The tests were conducted at temperatures of 300C – 350C and with current densities of 0.6 × 106 A/cm2 to 1.6 × 106A/cm2. In most cases an incubation period with negligible resistance increase is followed by a period of continuous, gradual resistance increase, attributed to formation and growth of voids in the conductor line. With further EM, the resistance curves show spike like features, with a sudden resistance increase, followed by a resistance decrease, often to values close to those before the start of EM. In other cases, no resistance decrease occurs, and the line fails. We present resistance data, microstructural observations and thermal calculations that suggest that the resistance decrease results from sudden, local Joule heating melting of conductor line segments and voids being partially filled by the back-flowing liquid Cu, which then solidifies. In some cases line failure results from liquid Cu erupting through the top surface passivation layer, rather than flowing back to fill voids in the line.
Design an Electroplated Frame Freestanding Specimen for Microtensile Testing of Submicron thin TaN and Cu Film
Authors: Lin Ming-Tzer , Tong Chi-Jia , Chiang Chung-Hsun 
Published: April 2011

AbstractA novel design electroplating spring frame structure specimen is demonstrated here. The specimen can be fit into a specially designed microtensile apparatus which is capable of carrying out a series of tests on submicron scale freestanding thin films.Certain thin films applicable in CMOS interconnect and low K materials were tested including sputtered Copper, Tantalum Nitride thin films. Metal specimens were fabricated by sputtering. For Tantalum Nitride film samples, Nitrogen gas was introduced into the chamber during sputtering Tantalum films on the silicon wafer.We found the modulus of Copper and Tantalum Nitride thin films thin films with thickness of 200 to 800nm at room temperature.