High Alignment Accuracy Research Articles

Multichip-to-Wafer Three-Dimensional Integration Technology Using Chip Self-Assembly With Excimer Lamp Irradiation

Self-assembly of multichips with metal microbump electrodes is demonstrated by using water surface tension to increase the stacking throughput/yield and chip alignment accuracy of conventional chip-to-wafer 3-D integration. Three-dimensional microbump interconnects are formed by self-assembly with thermal compression at 200 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}\hbox{C}$</tex></formula> . Chips with In–Au microbumps with pitches of 10 and 20 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu\hbox{m}$</tex></formula> are tightly bonded to Si wafers after the flip-chip self-assembly process, resulting in high alignment accuracies of 0.8 and 0.2 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu\hbox{m}$</tex></formula> in the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$x$</tex> </formula> - and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$y$</tex></formula> -directions, respectively. Selective hydrophilization by 172-nm excimer lamp irradiation gives a high wettability contrast between hydrophilic chip bonding areas and hydrophobic surrounding areas on the wafers. This assists high-precision multichip self-assembly. A 2500-In–Au-microbump daisy chain is formed with a yield of 100% by flip-chip self-assembly, and it exhibits ohmic contact. The resistance is sufficiently low for 3-D large-scale integration application, being comparable to that obtained by conventional mechanical chip alignment.

Hall effect measurements on InAs nanowires

We have processed Hall contacts on InAs nanowires grown by molecular beam epitaxy using an electron beam lithography process with an extremely high alignment accuracy. The carrier concentrations determined from the Hall effect measurements on these nanowires are lower by a factor of about 4 in comparison with those measured by the common field-effect technique. The results are used to evaluate quantitatively the charging effect of the interface and surface states.

Fabrication of In-Doped ZnO Scintillator Mounted on a Vacuum Flange

High quality In-doped ZnO single crystal was grown using the hydrothermal method. The growth rate for both ; and ; directions is about 80 μm/day. The X-ray rocking curve (XRC) full width at half maximum (FWHM) of the (0002) reflection is 24.2 arcsec. In order to make it possible to use this material as a scintillator for in situ imaging of soft X-ray laser with high spatial resolution, we prepared an In-doped ZnO wafer (9.0 mm x 9.0 mm x 0.75 mm) and mounted it on a vacuum flange. The decay time constant is evaluated to be 120 ps, therefore making it an ideal scintillator for in situ imaging device of soft X-ray laser with high spatial resolution. Furthermore, In-doped ZnO scintillator with such short decay time constant is suitable for high accuracy alignment and synchronization of ultrafast, short wavelength laser sources for pump-and-probe experiments.

High accuracy alignment facility for the receiver and transmitter of the BepiColombo Laser Altimeter

The accurate co-alignment of the transmitter to the receiver of the BepiColombo Laser Altimeter is a challenging task for which an original alignment concept had to be developed. We present here the design, construction and testing of a large collimator facility built to fulfill the tight alignment requirements. We describe in detail the solution found to attenuate the high energy of the instrument laser transmitter by an original beam splitting pentaprism group. We list the different steps of the calibration of the alignment facility and estimate the errors made at each of these steps. We finally prove that the current facility is ready for the alignment of the flight instrument. Its angular accuracy is 23 μrad.

SINA: Accurate high-throughput multiple sequence alignment of ribosomal RNA genes

Motivation: In the analysis of homologous sequences, computation of multiple sequence alignments (MSAs) has become a bottleneck. This is especially troublesome for marker genes like the ribosomal RNA (rRNA) where already millions of sequences are publicly available and individual studies can easily produce hundreds of thousands of new sequences. Methods have been developed to cope with such numbers, but further improvements are needed to meet accuracy requirements.Results: In this study, we present the SILVA Incremental Aligner (SINA) used to align the rRNA gene databases provided by the SILVA ribosomal RNA project. SINA uses a combination of k-mer searching and partial order alignment (POA) to maintain very high alignment accuracy while satisfying high throughput performance demands.SINA was evaluated in comparison with the commonly used high throughput MSA programs PyNAST and mothur. The three BRAliBase III benchmark MSAs could be reproduced with 99.3, 97.6 and 96.1 accuracy. A larger benchmark MSA comprising 38 772 sequences could be reproduced with 98.9 and 99.3% accuracy using reference MSAs comprising 1000 and 5000 sequences. SINA was able to achieve higher accuracy than PyNAST and mothur in all performed benchmarks.Availability: Alignment of up to 500 sequences using the latest SILVA SSU/LSU Ref datasets as reference MSA is offered at http://www.arb-silva.de/aligner. This page also links to Linux binaries, user manual and tutorial. SINA is made available under a personal use license.Contact: epruesse@mpi-bremen.deSupplementary information: Supplementary data are available at Bioinformatics online.

Beam Characteristics of Positively and Negatively Charged Droplets Generated by Vacuum Electrospray of an Ionic Liquid

To develop a vacuum-electrospray beam source for secondary ion mass spectrometry (SIMS), beam characteristics of charged droplets electrosprayed in vacuum were investigated in the negative-ion mode as well as the positive-ion mode. A quaternary ammonium ionic liquid was tested. Experimental results showed that there are differences as well as similarities between the positive-ion mode and the negative-ion mode. Beam current changed greatly with capillary voltage and the flow rate of the ionic liquid. Transient response analysis showed that the vacuum electrospray generated a mixed beam consisting of charged particles of smaller m/z values (m/z∼103) and charged droplets of larger m/z values (m/z∼105 to 106). It turned out that the m/z values of the charged droplets diminished with increasing capillary voltage. Using a three-dimensional positioning stage, the capillary position dependence on the beam characteristics was measured. It proved to be of great importance to align the central axis of a capillary with those of apertures in order to maximize the current component of the charged droplets of the larger m/z values and minimize the ratio of the current component of the smaller m/z values. A high alignment accuracy proved to be required at small gap lengths between a capillary tip and a counter electrode.

Multichip Self-Assembly Technology for Advanced Die-to-Wafer 3-D Integration to Precisely Align Known Good Dies in Batch Processing

An advanced die-to-wafer 3-D integration using a surface-tension–driven multichip self-assembly technology was proposed to 3-D stack a large number of known good dies (KGDs) in batch processing. The parallel self-assembly with a unique multichip pick-up tool was newly applied to die-to-wafer 3-D integration to overcome throughput and yield problems in conventional 3-D integration approaches. In addition, novel batch transfer of chips self-assembled on a carrier wafer to the corresponding target wafer was demonstrated. By using the multichip self-assembly, many KGDs can be precisely aligned and temporarily placed on a carrier wafer all at once, and then, the self-assembled KGDs can be simultaneously transferred to another target wafer in a face-to-face bonding manner at the wafer level. Average alignment accuracy was found to be approximately 400 nm when a hundred 3-mm-square chips were self-assembled on carrier wafers with small droplets of an aqueous solution. The alignment accuracy was experimentally proven to be fairly dependent on liquid surface tension as a self-assembly parameter. The liquid wettability contrast between the chip assembly areas and the surrounding areas formed on carrier wafers was another key parameter for alignment accuracy. The former and the latter areas were rendered high hydrophilic and hydrophobic. These areas, respectively, showed water contact angles less than 5 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$^{\circ}$</tex></formula> and 115 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex></formula> . Therefore, various sizes of chips (3 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\,\times\,$</tex></formula> 3 mm, 5 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\,\times\,$</tex></formula> 5 mm, 4 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\,\times\,$</tex></formula> 9 mm, and 10 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\,\times\,$</tex></formula> 10 mm) were self-assembled on a carrier wafer with high alignment accuracy, and further, the self-assembled chips were successfully transferred to the other faced target wafer in a batch.

Development and Experimental Validation of a 3-D Solder Self-Alignment Model for Alignment Accuracy Prediction of Flip-Chip Assembly

We describe a 3-D model for predicting the self-alignment accuracy of solder flip-chip assemblies. The model was developed using a force optimization method based on an explicit regression model, and validated experimentally using flip-chip test vehicles. The experimental results correlate with the model prediction to within 3% for the lateral alignment and 2% for the standoff height. The effects of important manufacturing parameters such as solder volume variations and distributions, chip mass, and die tilt, on the post-assembly alignment accuracies were investigated and characterized with the model. This model can be used to aid in the design of flip-chip assemblies requiring high alignment accuracies, such as those found in optoelectronics packaging.

Demonstration and Electrical Performance Investigation of Wafer-Level Cu Oxide Hybrid Bonding Schemes

Wafer-level Cu oxide hybrid bonding owns a number of merits, including simultaneous formations of electrical and mechanical bonds, underfill free, high alignment accuracy, increasing bond strength, and excellent reliability performance in 3-D integration. This letter demonstrates the fabrication of wafer-level Cu oxide hybrid bonding. Investigations of experimental and electrical simulation data of Cu oxide hybrid bonding structures are reported. Their alignment accuracy, frequency responses, and passive elements are compared for 3-D integration applications.

62.2: Development of Polymer Light‐Emitting Diode (PLED) Displays using The Relief Printing Method

AbstractWe have developed high resolution organic light emitting diode(OLED) displays by using a relief printing method. [1] With this method, high resolution OLED fabrication could be realized with high efficiency material usage. We have already reported development of a 5inch full color display.[2] In this paper we report about our prototype 7.4‐inch full color OLED display with ORTUS Technology Co. Ltd. A higher alignment accuracy is needed because we use a new TFT backplane which has a narrower pitch between each pixel than previously to make the pixel apertures larger and achieve a larger pixel size. In general, printing methods have an issue with brightness uniformity. We made the panels, without the unintentional color mixing between neighboring pixels by improving the alignment accuracy of the relief printing method.

A simple and scalable graphene patterning method and its application in CdSe nanobelt/graphene Schottky junction solar cells

We have developed a simple and scalable graphene patterning method using electron-beam or ultraviolet lithography followed by a lift-off process. This method, with the merits of: high pattern resolution and high alignment accuracy, being free from additional etching or harsh processes, being universal to arbitrary substrates, and being compatible to Si microelectronic technology, can easily be applied to diverse graphene-based devices, especially in array-based applications, where large-scale graphene patterns are desired. We have applied this method to fabricate CdSe nanobelt (NB)/graphene Schottky junction solar cells, which have potential applications in integrated nano-optoelectronic systems. A typical as-fabricated solar cell shows excellent photovoltaic behavior, with an open-circuit voltage of ∼0.51 V, a short-circuit current density of ∼5.75 mA cm(-2), and an energy conversion efficiency of ∼1.25%. We attribute the high performance of the cell to the as-patterned high-performance graphene, which can form an ideal Schottky contact with CdSe NB. Our results suggest that both the developed graphene patterning method and the as-fabricated CdSe NB/graphene Schottky junction solar cells have reachable application prospects.

From 2D Lithography to 3D Patterning

Lithography as developed for IC device fabrication is a high volume high accuracy patterning technology with strong 2 dimensional (2D) characteristics. This 2D nature makes it a challenge to integrate this technology in a 3 dimensional (3D) manufacturing environment. This article addresses the performance of a waferstepper (ASML PAS5000) in several 3D processes ranging form waferbonding and thinning to dual side processing with through silicon vias (TSV). Four different generic expose/etch strategies are discussed to fabricate vertical micro sieves, vertical through wafer silicon plate springs, dual side interconnect with TSV and vertical electrodes in deep silicon channels. It is concluded, that despite the 2D nature of advanced waferstepper lithography a wide range of 3D structures can be fabricated. The multi point alignment capabilities of a waferstepper can improve the overlay in several 3D manufacturing processes and the high accuracy alignment system can be used as a metrology tool for further development of 3D integration processes.

Simple and high-accuracy integration for parallel optical subassembly with 120-Gbits/s data transmission

Abstract. We integrate transmitting and receiving parallel optical sub-assemblies POSAs that are suitable for high-speed and parallel opticalmodules between optical components by using a simple and high-accuracy alignment technique. Characteristics of the proposed POSAsinclude a low coupling loss of 0.75 dB, a wide bandwidth for 10 Gbits/stransmission per channel, and low optical and electrical crosstalk of lessthan 30 dB. As a result, a data transmission rate of 10 Gbits/s 12channels is well demonstrated with clean eye diagrams. © 2010 Society ofPhoto-Optical Instrumentation Engineers. DOI: 10.1117/1.3486205 Subject terms: parallel optical subassembly; microlens; silicon optical bench;passive alignment technique . Paper 100082R received Jan. 30, 2010; revised manuscript received Jul. 16,2010; accepted for publication Jul. 23, 2010; published online Sep. 2, 2010. 1 Introduction With the increasing construction of servers in office build-ings and data centers, the networks of these centers must beable to provide high-capacity data transmissions.Also, highdata transmissions are required for various multimedia ser-vices such as real-time data communications. Thus, thedriving force for these requirements has stimulated the re-cent development of parallel optical interconnections.

Adaptive Lost Motion Compensation Using Disturbance Observer

Lost motion is a major disturbance that affects the contouring accuracy of NC machine tools. Although NC machine tools with plain bearing guideways are capable of high alignment accuracy, their lost motion sometimes varies according to motion conditions such as position, velocity and moving length. Conventional backlash compensation with a constant parameter applied to the lost motion causes contouring error due to inadequate compensation. This paper presents a model of a two-body system with a position-dependent spring and motion-condition-dependent friction that exhibits varying lost motion, and an adaptive compensation method for the lost motion is derived from the model. A tuning method for the compensation parameters is also proposed. Stiffness of the position-dependent spring is calculated from the specifications of mechanical parts, such as a ball screw, bearings and a coupling. The varying friction is estimated by a disturbance observer. Contouring accuracy in a circular test of NC machine tools demonstrates the improved performance enabled by the proposed method.

Electrostatic attraction and surface-tension-driven forces for accurate self-assembly of microparts

Self-assembly is not widely used in industrial micro-fabrication, although it can potentially involve assembly processes that are considerably less complex. A variety of procedures for self-alignment of parts have been introduced and investigated lately. These procedures mainly utilise capillary, gravitational or electrostatic forces in the micro-scale. This paper investigates two different concepts for accurate self-assembly of parts. One is well described in the literature by third parties and involves the alignment of parts by utilising the surface tensions of micro-scaled adhesive films, which are selectively coated on hydrophobic alignment structures. In the present publication the influence of the dimensions of such structured alignment sites on the process flow is discussed. The second concept is a novel approach to accomplish self-alignment of micro-structures with electrostatic attraction. Several complementary and electrically conductive micro-structured patterns serve as binding sites for the alignment of parts in this approach. In order to obtain knowledge of how these two approaches operate, they have been modelled and simulated. Additionally, in order to analyse the feasibility of these procedures and to verify simulation results experiments have been performed on micro-structured parts and substrates. In particular, the layout of the alignment structures and the size of the parts were identical for both described concepts in the experimental work; therefore, these two methods were compared. With the self-assembly procedure that utilises electrostatic attraction, high alignment accuracies and forces, affecting the part over large distances, were observed. Finally, parts with micro-structured binding sites, which were as small as [email protected]^2, could accurately be self-aligned with electrostatic attraction.

A novel method for fabricating sub-16 nm footprint T-gate nanoimprint molds

A novel method for fabricating nanoimprint lithography (NIL) molds for T-shaped gates(T-gates) for high speed transistors is proposed and demonstrated. This method uses NIL,low pressure chemical vapor deposition and reactive ion etching processes, and avoids costlyelectron beam lithography and high accuracy alignment technology. Using the T-gatenanoimprint molds fabricated by this novel method, T-gates with a footprint as small assub-16 nm were achieved. This method can be extended to fabricate a broad range of 3Dnanostructures.

Ultra-Small Laser Scanning Module with High Accuracy Alignment

We report that an ultra-small laser scanning module of millimeter size was realized. This laser scanning module consists of silicon substrate, a laser diode array with multi-emitter, and microprisms. The microprism measures 180μm wide, 100μm high, and 80μm thick. The smaller the optical elements used, the more precise the alignment accuracy required. The microprisms and alignment pins for laser diode array are fabricated on the same silicon substrate using MEMS technology. Then the laser diode array is attached to the silicon substrate by setting with the alignment pins. The alignment accuracy was ±2.8μm for the interval between the laser diode array and microprisms. The rotational angle accuracy of each axis was within ±0.3 degrees. This high alignment accuracy has been achieved without camera.

Kalign2: high-performance multiple alignment of protein and nucleotide sequences allowing external features

In the growing field of genomics, multiple alignment programs are confronted with ever increasing amounts of data. To address this growing issue we have dramatically improved the running time and memory requirement of Kalign, while maintaining its high alignment accuracy. Kalign version 2 also supports nucleotide alignment, and a newly introduced extension allows for external sequence annotation to be included into the alignment procedure. We demonstrate that Kalign2 is exceptionally fast and memory-efficient, permitting accurate alignment of very large numbers of sequences. The accuracy of Kalign2 compares well to the best methods in the case of protein alignments while its accuracy on nucleotide alignments is generally superior. In addition, we demonstrate the potential of using known or predicted sequence annotation to improve the alignment accuracy. Kalign2 is freely available for download from the Kalign web site (http://msa.sbc.su.se/).

Alignment measurement method for imprint lithography using moiré fringe pattern

A simple and high-accuracy alignment measurement method based on a moire fringe pattern is proposed. It involves relative rotation positioning and relative linear displacement measurement. Taking full advantage of the magnification effect of moire fringe in angular and linear displacement, the relative rotation between the template and the wafer is determined first by measuring the inclination of the moire fringe, and then the relative linear displacement between them is acquired by evaluating the spatial phase shift of two matched moire fringes. The frequency components in the orthogonal directions of the fringe image obtained by a fast Fourier transform (FFT) and zooming process are used to measure the inclination of the moire fringe. By selecting different orthogonal directions, a moire fringe with any inclination can be measured accurately. When gratings are adjusted to parallel, a frequency-domain analysis is also used to extract the spatial phase of fringes at a given frequency. According to the relationship between spatial phase and linear displacement, the misalignment is detected. In experiments, the repeatability for the misalignment measurement has reached 4.8 nm (3).

Slider—maximum use of probability information for alignment of short sequence reads and SNP detection

Motivation: A plethora of alignment tools have been created that are designed to best fit different types of alignment conditions. While some of these are made for aligning Illumina Sequence Analyzer reads, none of these are fully utilizing its probability (prb) output. In this article, we will introduce a new alignment approach (Slider) that reduces the alignment problem space by utilizing each read base's probabilities given in the prb files.Results: Compared with other aligners, Slider has higher alignment accuracy and efficiency. In addition, given that Slider matches bases with probabilities other than the most probable, it significantly reduces the percentage of base mismatches. The result is that its SNP predictions are more accurate than other SNP prediction approaches used today that start from the most probable sequence, including those using base quality.Contact: nmalhis@bcgsc.caSupplementary information and availability: http://www.bcgsc.ca/platform/bioinfo/software/slider