Numerical Study For Acoustic Micro-Imaging Of Three Dimensional Microelectronic Packages

Complex structures and multiple interfaces of modern microelectronic packages complicate the interpretation of acoustic data. This study has four novel contributions. 1) Contributions to the finite element method. 2) Novel approaches to reduce computational cost. 3) New post processing technologies to interpret the simulation data. 4) Formation of theoretical guidance for acoustic image interpretation. The impact of simulation resolution on the numerical dispersion error and the exploration of quadrilateral infinite boundaries make up the first part of this thesis's contributions. The former focuses on establishing the convergence score of varying resolution densities in the time and spatial domain against a very high fidelity numerical solution. The latter evaluates the configuration of quadrilateral infinite boundaries in comparison against traditional circular infinite boundaries and quadrilateral Perfectly Matched Layers. The second part of this study features the modelling of a flip chip with a 140µm solder bump assembly, which is implemented with a 230MHz virtual raster scanning transducer with a spot size of 17µm. The Virtual Transducer was designed to reduce the total numerical elements from hundreds of millions to hundreds of thousands. Thirdly, two techniques are invented to analyze and evaluate simulated acoustic data: 1) The C-Line plot is a 2D max plot of specific gate interfaces that allows quantitative characterization of acoustic phenomena. 2) The Acoustic Propagation Map, contour maps an overall summary of intra sample wave propagation across the time domain in one image. Lastly, combining all the developments. The physical mechanics of edge effects was studied and verified against experimental data. A direct relationship between transducer spot size and edge effect severity was established. At regions with edge effect, the acoustic pulse interfacing with the solder bump edge is scattered mainly along the horizontal axis. The edge effect did not manifest in solder bump models without Under Bump Metallization (UBM). Measurements found acoustic penetration improvements of up to 44% with the removal of (UBM). Other acoustic mechanisms were also discovered and explored. Defect detection mechanism was investigated by modelling crack propagation in the solder bump assembly. Gradual progression of the crack was found have a predictable influence on the edge effect profile. By exploiting this feature, the progress of crack propagation from experimental data can be interpreted by evaluating the C-Scan image

Cutting Edge Nanotechnology

The main purpose of this book is to describe important issues in various types of devices ranging from conventional transistors (opening chapters of the book) to molecular electronic devices whose fabrication and operation is discussed in the last few chapters of the book. As such, this book can serve as a guide for identifications of important areas of research in micro, nano and molecular electronics. We deeply acknowledge valuable contributions that each of the authors made in writing these excellent chapters

Low-temperature electroluminescence excitation mapping of excitons and trions in short channel monochiral carbon nanotube device

Single walled carbon nanotubes as emerging quantum-light sources may fill a technological gap in silicon photonics due to their potential use as near infrared, electrically driven, classical or non-classical emitters. Unlike in photoluminescence, where nanotubes are excited with light, electrical excitation of single tubes is challenging and heavily influenced by device fabrication, architecture and biasing conditions. Here we present electroluminescence spectroscopy data of ultra short channel devices made from (9,8) carbon nanotubes emitting in the telecom band. Emissions are stable under current biasing and no quenching is observed down to 10 nm gap size. Low-temperature electroluminescence spectroscopy data also reported exhibits cold emission and linewidths down to 2 meV at 4 K. Electroluminescence excitation maps give evidence that carrier recombination is the mechanism for light generation in short channels. Excitonic and trionic emissions can be switched on and off by gate voltage and corresponding emission efficiency maps were compiled. Insights are gained into the influence of acoustic phonons on the linewidth, absence of intensity saturation and exciton exciton annihilation, environmental effects like dielectric screening and strain on the emission wavelength, and conditions to suppress hysteresis and establish optimum operation conditions

Kupari-tina mikroliitosten karakterisointimenetelmät

The microelectronics industry constantly aspires to shrink the device features. At the package level, this implies a decrease in the interconnect size leading to small volume interconnections that are commonly called micro-connects. Smaller material volumes may give rise to new reliability challenges, such as open circuits, due to Kirkendall voiding. The root cause(s) for Kirkendall voiding is not yet clear and the methods for characterization are still varied. This thesis reviews techniques to characterize the microstructure and impurities in Cu-Sn micro-connects. The evaluated techniques are Auger Electron Spectroscopy (AES), Electron Energy Loss Spectroscopy (EELS), Energy-Dispersive X-Ray Spectroscopy (EDX), X-Ray Spectroscopy (XPS), Secondary Ion Mass Spectrometry (SIMS), Rutherford Backscattering Spectrometry (RBS), Elastic Recoil Detection Analysis (EELS), Transmission Electron Microscopy (TEM), Focused Ion Beam (FIB), and Scanning Acoustic Microscopy (SAM). From the reviewed techniques, EDX, FIB, SAM, and TEM are used in the experimental section. For the first time, impurities are measured directly inside Kirkendall voids. It was discovered that the Kirkendall voids in annealed Cu-Sn samples contained a significant amount of chlorine and oxygen. The ASTM grain size counting method was applied to FIB-polished samples. It was observed that the grain size did not increase by annealing at 150 ◦C. Furthermore, for the first time, GHz-SAM was used to characterize Kirkendall voids. The technique is promising but it is still affected by the low lateral resolution.Mikroelektroniikkateollisuus pyrkii jatkuvasti pienentämään laitekokoa. Paketointitasolla tämä tarkoittaa sitä, että sirujen välisten liitosten kokoluokka on siirtymässä kohti mikroliitoksia, jotka saattavat aiheuttaa uusia luotettavuusongelmia. Kirkendall-aukot ovat yksi syy kyseisiin luotettavuusongelmiin ja aukkojen alkuperä on vielä tuntematon. Sen lisäksi, mikroliitosten ja Kirkendall aukkojen karakterisointiin käytetään toisistaan poikkeavia menetelmiä eikä sopivista metodeista ole vielä yhteisymmärrystä. Tämä diplomityö tarkastelee kupari-tina mikroliitoksien mikrorakenteen ja epäpuhtauksien analysointiin käytettyjä menetelmiä. Tarkasteltavat menetelmät ovat Auger elektronispektroskopia (AES), epäelastinen elektronisironta (EELS), energiadispersiivinen röntgenspektroskopia (EDX), röntgenfotoelektronispektroskopia (XPS), sekundääri ionimassaspektroskopia (SIMS), Rutherford-takaisinsirontaspektroskopia (RBS), rekyylispektrometria (ERDA), läpäisyelektronimikroskopia (TEM), keskitetty ionisuihku (FIB) ja akustinen mikroskopia (SAM). Esitellyistä menetelmistä kokeellisessa osiossa käytettiin EDX:ää, FIB:ä, SAM:a ja (S)TEM:ä. Tässä diplomityössä on mitattu ensimmäistä kertaa epäpuhtauksia Kirkendall-aukkojen sisältä. Mittauksista saatiin selville, että hehkutettujen kupari-tina -näytteiden Kirkendall-aukot sisälsivät huomattavan määrän happea ja klooria. Raekokoa tarkasteltiin kiillottamalla näytteet FIB:llä ja soveltamalla ASTM:n raekoko -standardia. Työssä huomattiin, että raekoko ei kasvanut, jos näytteitä hehkutettiin 150 ◦C lämpötilassa. Tämä on myös ensimmäinen kerta, kun GHzSAM:a on käytetty Kirkendall-aukkojen tutkimiseen. Tulokset olivat lupaavia, mutta menetelmän alhainen sivuttaissuuntainen resoluutio on vielä rajoittava tekijä

Institute of Ion Beam Physics and Materials Research; Annual Report 1999

Summary of the Scientific Activities of the Institute in 1999: Highlight Reports / Short Contributions / Statistic

CMOS integration of inkjet-printed graphene for humidity sensing.

We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things.S.S. acknowledges Department of Science and Technology (DST), India for Ramanujan Fellowship to support the work (project no. SR/S2/RJN-104/2011). This work was (partly) supported through the EU FP7 project MSP (611887). T.H. acknowledges support from the Royal Academy of Engineering through a fellowship (Graphlex).This is the final version of the article. It was first available from NPG via http://dx.doi.org/10.1038/srep1737