Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session H28: Semiconductor Processing and Devices for Application |
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Sponsoring Units: FIAP Chair: Todd Brintlinger, Naval Research Laboratory Room: 291 |
Tuesday, March 14, 2017 2:30PM - 2:42PM |
H28.00001: Fabrication of Quench Condensed Thin Films Using an Integrated MEMS Fab on a Chip Richard Lally, Jeremy Reeves, Thomas Stark, Lawrence Barrett, David Bishop Atomic calligraphy is a microelectromechanical systems (MEMS)-based dynamic stencil nanolithography technique. Integrating MEMS devices into a bonded stacked array of three die provides a unique platform for conducting quench condensed thin film mesoscopic experiments. The atomic calligraphy Fab on a Chip process incorporates metal film sources, electrostatic comb driven stencil plate, mass sensor, temperature sensor, and target surface into one multi-die assembly. Three separate die are created using the PolyMUMPs process and are flip-chip bonded together. A die containing joule heated sources must be prepared with metal for evaporation prior to assembly. A backside etch of the middle/central die exposes the moveable stencil plate allowing the flux to pass through the stencil from the source die to the target die. The chip assembly is mounted in a cryogenic system at ultra-high vacuum for depositing extremely thin films down to single layers of atoms across targeted electrodes. Experiments such as the effect of thin film alloys or added impurities on their superconductivity can be measured in situ with this process. [Preview Abstract] |
Tuesday, March 14, 2017 2:42PM - 2:54PM |
H28.00002: A MEMS Based Stencil Lithography Approach to Nanomanufacturing Lawrence Barrett, Thomas Stark, Jeremy Reeves, Richard Lally, David Bishop We have developed a microelectromechanical systems (MEMS) based approach to nanomanufacturing called atomic calligraphy. Comb drive actuators position a stencil with sub-nanometer precision and material is deposited through the stencil on to a substrate. The MEMS device is aligned to the substrate using piezoelectric stages and capacitive and resistive measurements. Using the piezo stages in conjunction with the comb drive actuators, increases the writing range from the range of the comb drive actuators (\textasciitilde 10 $\mu $m) to the range of the piezo stages (5 cm) without sacrificing resolution. Among the advantages of this method is its scalability. Thousands of MEMS devices can be used to write structures in parallel, and if the stencil on each device contains an array of structures, 10$^{\mathrm{6}}$ to 10$^{\mathrm{8}}$ structures can be fabricated in parallel. Because there is no wet processing, this technique can be used to fabricate structures on a wide range of materials including many polymers. Arrays of optical metamaterials have been fabricated with this approach and characterized both with scanning electron microscopy (SEM) and optical techniques. [Preview Abstract] |
Tuesday, March 14, 2017 2:54PM - 3:06PM |
H28.00003: Wide actuation range cavity resonators based on MEMS Michael J. Burns, Juan M. Merlo, Luke D'Imperio, Michael J. Naughton Color filters are an important component of current imaging research. One important approximation for color filtering was recently reported by Li, \textit{et al.} [1]. Unfortunately, the principle employed does not allow the tuning of the cavity once it is fabricated. Here, we report a color filter by a different approach, using MEMS with actuation range on the order of hundreds of nanometers in spectral filtering. The fabrication process is based on photolithography, making it an easy to implement device. We show that the filtering area can be as large as 50 $\mu $m$^{\mathrm{2}}$, the actuation voltage on the order of several volts and the quality factor of about Q$=$30. Additionally, the tuning wavelength / voltage ratio is measured, in some of the samples, as 10 nm/V along the actuation range. Several applications are proposed, but we are particularly interested in the color filtering performance because of the wide range obtained. [1] Z. Li, \textit{et al.} ACS Photonics 2, 183 (2016). [Preview Abstract] |
Tuesday, March 14, 2017 3:06PM - 3:18PM |
H28.00004: Si nanostructures induced by ion-beam impact on SiO$_{\mathrm{2}}$ Camilla Ferreira de Sa Codeco, Sergio L.A. Mello, Germano M. Penello, Antonio C. F. Santos, Marcelo M. Sant'Anna, Krishynan S. F. M. Araujo Silicon oxide films are used in many fields due to its optical and electrical properties. One of its main applications includes the microelectronics industry, where the silicon suboxide (SiOx) can be used as a precursor for synthesis of silicon nanocrystals. Here we explore a synthesis route for these nanocrystals based on the impact of low energy ions in thin films of silicon dioxide. As the development of techniques for synthesis of nanostructures is continuous, it also becomes necessary to develop, in parallel, nanoscale characterization techniques compatible with nanometric spatial resolution. The combination of synchrotron radiation and Atomic Force Microscopy allows topographic imaging combined with nanometric infrared imaging and the measurement of IR spectra on chosen points on the images, which provide information about the vibrational modes of the solid. Our sample is a 50 nm thick silicon dioxide layer grown on top of a Si bulk. In this case we irradiate the thin film with a beam of Cs$+$ ions. It is possible to study the introduction of defects and disorder in the film by analyzing the changes in the normal modes of vibration of Si-O-Si in the film and to observe the nanostructure synthesis of Si nanocrystals with heights of the order of 70 nm. [Preview Abstract] |
Tuesday, March 14, 2017 3:18PM - 3:30PM |
H28.00005: Nonlinear Laser Lithography implementation for both ``normal'' and ``anomalous'' laser induced periodic structuring. Ihor Pavlov, Onur Tokel, Ozgun Yavuz, Ghaith Makey, Omer Ilday Laser Induced Periodic Surface Structuring (LIPSS) is one of the most prominent directions in laser-material interaction due to both practical and theoretical importance, especially after the discovery of Nonlinear Laser Lithography (NLL) [1], which opens new area for industrial application of LIPSS as an effective tool for controllable, highly ordered large area nanostructuring. LIPSS appear on the surface under laser beam in the form of periodical lines. The LIPSS, that appear perpendicular to laser polarization are called ``normal'', in contrast to ``anomalous'' LIPSS appearing parallel to the polarization. Although, NLL technique was already demonstrated for ``normal'' and ``anomalous'' LIPSS separately, up to now, there is no clear understanding of switching mechanism between these two modes. In presented paper we have shown that the mechanism relies on interplay between two feedbacks: long range, low intensity dipole-like scattering of light along the surface, and short range, high intensity plasmon-polariton wave. For the first time, we are able to create both types of LIPSS on the same surface by controlling these two feedbacks, obtaining highly-ordered large-area structured patterns in both modes. [1] Oktem et al. Nature Photonics 7, 897, (2013) [Preview Abstract] |
Tuesday, March 14, 2017 3:30PM - 3:42PM |
H28.00006: Monolithically integrated microfluidic channels in silicon for chip cooling Ahmet Turnali, Onur Tokel, Tahir Colakoglu, Mona Zolfaghari, Ihor Pavlov, Alpan Bek, Rasit Turan, Fatih Omer Ilday The challenge in scaling chips and increasing clock rates is mainly due to limitations in removing excess heat. In order to overcome the stubborn heat removal problem, air and liquid based cooling with fans and metallic plates is used. However, these methods have low heat-removal efficiency and undesired thermal resistance. To solve these problems, microfluidic cooling approaches are emerging, which exploit microchannels positioned on wafer surfaces. Here, we report a laser-based method, which enables carving fully embedded microfluidic channels deep inside Si without damaging wafer surfaces. The method relies on our recent results[1], which enables creation of structural modifications inside Si. Modified subsurface volumes are then chemically etched away with a custom etchant to create the microchannels inside the chip. The microchannels carrying liquid coolant are then experimentally shown to cool Si chips, which is the first demonstration of monolithically-cooled chips with in-chip microchannels. This constitutes a disruptive method that can facilitate multi-level integration of chips, and increased clock rates, and may also lead to in-chip bio-applications. [1] Turnali et.al. Laser-driven self-organised functional 3D superstructures deep inside silicon, Nature (under review) [Preview Abstract] |
Tuesday, March 14, 2017 3:42PM - 3:54PM |
H28.00007: Laser slicing of silicon wafers Onur Tokel, Ahmet Turnali, Tahir Colakoglu, Ihor Pavlov, Mona Zolfaghari Borra, Ghaith Makey, Alpan Bek, Raşit Turan, Fatih Omer Ilday Functional electrical, MEMS and solar-cell devices are fabricated on silicon through the highly successful and established lithography techniques. However, these methods are geared towards processing from surface, are expensive, require masks, and in many cases involve multi-step procedures. Here, we present a new laser-slicing method for creating thin-sliced (30 um) Si chips, which constitutes the first time Si wafers are sliced with lasers. We first exploit nonlinear interactions of a focused laser in creating 1um-wide, wall-like structures fabricated in Si. These subsurface structures are then selectively etched to demonstrate a plethora of functional elements and 3D architectures inside Si [1]. In particular, we demonstrate the first laser-carved through-Si vias for intra-chip interconnects, laser-sculpted high-aspect-ratio micropillar arrays and thin-wafers for solar-cell applications, and micro-cantilevers for MEMS and biomedicine. This new method complements available techniques by taking advantage of the bulk of Si in 3D, and can pave the way towards entirely new multilevel and multifunctional solar-cell and MEMS devices. [1] Tokel et. al. Laser-driven self-organised functional 3D superstructures deep inside silicon, Nature (under review). [Preview Abstract] |
Tuesday, March 14, 2017 3:54PM - 4:06PM |
H28.00008: Strategies for alignment and e-beam contact to buried atomic-precision devices in Si Jonathan Wyrick, Pradeep Namboodiri, Xiqiao Wang, Roy Murray, Joseph Hagmann, Kai Li, Michael Stewart, Curt Richter, Richard Silver STM based hydrogen lithography has proven to be a viable route to fabrication of atomic-precision electronic devices. The strength of this technique is the ability to control the lateral placement of phosphorus atoms in a single atomic layer of Si with sub-nanometer resolution. However, because of limitations in the rate at which a scanning probe can pattern a device, as well as the ultimate size of contacts that can be fabricated (on the order of a micron in length), making electrical contact to STM fabricated devices encased in Si is nontrivial. One commonly implemented solution to this challenge is to choose the exact location on a Si surface where a device is to be patterned by STM and to design fiducials to aid in navigating the probe to that predetermined location. We present results from an alternate strategy for contacting buried devices based on performing the STM lithography fabrication first, and determination of the buried structure location after the fact using topographically identifiable STM fabricated fiducials. AFM, scanning capacitance, and peak force Kelvin microscopy as well as optical microscopy techniques are evaluated as a means for device relocation and to quantify the comparative accuracy of these techniques. [Preview Abstract] |
Tuesday, March 14, 2017 4:06PM - 4:18PM |
H28.00009: Characterization of reactive magnetron sputtering plasma during thin film deposition. Rylan Gordon, Hasitha Mahabaduge Reactive magnetron sputtering is used extensively as a thin film deposition technique. During sputtering, a plasma is generated. The evolution of the plasma dictates the thin film composition and structure. The residence time of a reactive gas molecule, the mean time it remains in the process chamber before being pumped away also plays an important role in reactive sputtering. We simulated the residence time and partial pressure of the respective reactive gasses in magnetron sputtering environment using Matlab. Using Optical Emission Spectroscopy we confirmed the trend in mean residence time of the reactive gasses. The thin film properties of reactively sputtered aluminum-doped zinc oxide will be presented along with the correlation to the plasma properties during the deposition. [Preview Abstract] |
Tuesday, March 14, 2017 4:18PM - 4:30PM |
H28.00010: Domain-confined growth of hollow semiconductor nanocrystals indcued by an electron beam Luping Tang, Longbing He, Litao Sun Design and synthesis of hollow nanocrystals (NCs) have been rapidly developed due to their large surface area, low density and high loading capacity. In this paper, we report a domain-confined growth of hollow CdSeS NCs through both thermal treatments and electron beam irradiation on the templating CdSe/CdS NCs. We demonstrate that sublimation and regrowth of the NCs can be well controlled by the heating temperature and beam irradiation. With a preformed thin carbon shell on the templating NCs, transformation of the partically sublimated CdSe/CdS NCs into hollow CdSeS can also be restricted inside the shell's inter space. Furthermore, the regrowth of hollow CdSeS NCs is found to be sensitive to the volume ratio of the remained CdSe/CdS core to the carbon sphere. Only a certain portion of the CdSe/CdS cores can be successfully converted into hollow NC structures. These physical manipulations of NCs indicate that the electron beam has unique superiority over other techniques on farbication of nanostructures. Especially for individual NCs, such an ability of electron beams enables discrepant tailoring of their structures, and thereby to some extent shed light on in-situ design and construction of NC based nanodevices. [Preview Abstract] |
Tuesday, March 14, 2017 4:30PM - 4:42PM |
H28.00011: Magnetometry with Quartz Tuning Fork Lu Chen, Fan Yu, Ziji Xiang, Colin Tinsman, Tomo Asaba, Benjamin Lawson, Weida Wu, Lu Li Quartz tuning forks are the driving force for the recent progress of atomic force microscopy. As a high Q oscillator, it is potentially a frequency modulated cantilever for magnetometry. In our study, we developed a new method for mounting tuning forks. With a bismuth single crystal attached to a free prong, the tuning fork device is driven by AC voltage and the responding current is measured at the same time. We observed sharp resonance in both the magnitude and phase of current at temperature down to 0.35K. In magnetic field up to 10 T, the phase of current shows quantum oscillations which are periodic with respect to $\frac{1}{B}$. The extracted Fermi surfaces are consistent with those of bismuth crystals. [Preview Abstract] |
Tuesday, March 14, 2017 4:42PM - 4:54PM |
H28.00012: Influence of self-ordered Au nanoparticles on chemically textured Si surfaces with improved antireflection and hydrophobicity. Chetan Saini, Arabinda Barman, Mohit Kumar, B. Satpati, T. Som, Aloke Kanjilal A facile approach to improve hydrophobicity of chemically etched Si pyramids is presented by introducing Au nanoparticles (NPs). Initially, a clear transformation of pristine Si from hydrophilic to hydrophobic is established by chemical texturing, and manifested by observing an increase in contact angle (CA) from 58$^{\mathrm{0\thinspace }}$to 98$^{\mathrm{0}}$. X-ray diffraction studies reveal the evolution of a tensile strain in microscale Si pyramids followed by the formation of conformal Au layers without showing any significant change in CA (96$^{\mathrm{0}})$. However, the development of Au NPs with additional self-ordered structures at the pyramid edges at 400 $^{\mathrm{0}}$C gives a sharp rise in CA up to 118$^{\mathrm{0}}$, while the underlying phenomenon has been discussed in the light of a decrease in solid fractional surface area according to the Wenzel model. Detailed transmission electron microscopy investigations, however, suggest that Au and Si are immiscible at the Au/Si interfaces. Moreover, a sharp reduction of specular reflectance, especially in the ultraviolet region up to 0.4 {\%} has been manifested from ultraviolet-visible spectroscopy and discussed in details. [Preview Abstract] |
Tuesday, March 14, 2017 4:54PM - 5:06PM |
H28.00013: Film-Wafer Bonding for Thermal Studies of a Twist Si Grain Boundar Dongchao Xu, Bo Xiao, Hongbo Zhao, Qing Hao At the nanoscale, interfaces play an important role in suppressing the phonon transport. A good example of such interfaces can be grain boundaries within a polycrystal [1]. In molecular dynamics simulations, the interfacial thermal resistance of a grain boundary has a strong dependence on the misorientation between two grains [2,3]. Such dependence has been found on bonded identical Al2O3 wafers with relative rotation, representing a twist grain boundary [4]. However, the measurements on similar twist Si grain boundaries are still lacking. In this work, a 70-nm-thick Si thin film was hot pressed onto a Si wafer to represent a grain boundary. Such film-wafer bonding allowed better contact compared with bonding between two rigid wafers. The obtained film-wafer interfacial thermal resistance was measured as a function of the rotation angle between the film and the wafer. The results were further compared with the predictions in previous studies. References: [1] Cahill et al., J. Appl. Phys. 93, 793 (2003). [2] Cao et al., J. Appl. Phys. 111, 053529 (2012). [3] Kimmer et al., Phys. Rev. B 75, 144105 (2007). [4] Tai et al., Appl. Phys. Lett. 102, 034101 (2013). [Preview Abstract] |
Tuesday, March 14, 2017 5:06PM - 5:18PM |
H28.00014: Study of Damage and Recovery of Electron Irradiated Polyimide using EPR and NMR Spectroscopy Sunita Humagain, Jessica Jhonson, Phillip Stallworth, Daniel Engelhart, Elena Plis, Dale Ferguson, Russell Cooper, Ryan Hoffmann, Steve Greenbaum The main objective of this research is to probe radical concentrations in electron irradiated polyimide (PI, Kapton\textregistered ) and to examine the impact on the electrical properties using EPR and NMR spectroscopy. PI is an electrical insulator used in space missions as a thermal management blanketing material, it is therefore critical for spacecraft designers to understand the nature of electron transport (electrical conductivity) within the bulk of the material. The recovery mechanism (radical evolution) of PI in vacuum, argon and air after having been subjected to 90 KeV electron irradiation, was studied. The formation and subsequent exponential decay of the radical concentrations was recorded using EPR. This signal decay agrees well with the recovery mechanism being probed by electrical conductivity measurements and implies a strong relation between the two. To investigate the distribution of radicals in the polymer, $^{\mathrm{1}}$H NMR relaxation time (T$_{\mathrm{1}})$ were measured at 300MHz. Additional NMR experiments, in particular $^{\mathrm{13}}$C, were performed to search for direct evidence of structural defects. [Preview Abstract] |
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