Investigating on Through Glass via Based RF Passives for 3-D Integration

Due to low dielectric loss and low cost, glass is developed as a promising material for advanced interposers in 2.5-D and 3-D integration. In this paper, through glass vias (TGVs) are used to implement inductors for minimal footprint and large quality factor. Based on the proposed physical structure, the impact of various process and design parameters on the electrical characteristics of TGV inductors is investigated with 3-D electromagnetic simulator HFSS. It is observed that TGV inductors have identical inductance and larger quality factor in comparison with their through silicon via counterparts. Using TGV inductors and parallel plate capacitors, a compact 3-D band-pass filter (BPF) is designed and analyzed. Compared with some reported BPFs, the proposed TGV-based circuit has an ultra-compact size and excellent filtering performance

128 × 128 silicon photonic MEMS switch package using glass interposer and pitch reducing fibre array

We design and fabricate the packaging of 128 × 128 silicon photonic MEMS switch device using through glass via (TGV) interposer and pitch reducing fibre array. The switch device contains 16384 MEMS switch cells and 272 grating couplers spaced at 63.5 μm in a compact footprint of 17.4 mm × 16 mm. The apodised grating couplers designed for 1300 nm have an insertion loss of 2.5 dB/facet at 10° coupling angle. The 0.5 mm thick glass interposer contains 512 electrical vias while the pitch reducing optical coupling array is polished to 40° for planar coupling

Doctor of Philosophy

dissertationPrecise optical neural stimulation is an essential element in the use of optogenetics to elicit predictable neural action potentials within the brain, but accessing specific neocortical layers, light scattering, columniation, and ease of tissue damage pose unique challenges to the device engineer. This dissertation presents the design, simulation, microfabrication, and characterization of the Utah Optrode Array (UOA) for precise neural tissue targeting through three main objectives: 1. Maskless wafer-level microfabrication of optical penetrating neural arrays out of soda- lime glass: Utah Optrode Array. 2. Utah Optrode Array customization using stereotactic brain atlases and 3D CAD modeling for optogenetic neocortical interrogation in small rodents and nonhuman primates. 3. Single optrode characterization of the UOA for neocortical illumination. Maskless microfabrication techniques were used to create 169 individual 9 × 9 arrays 3.85 mm × 3.85 mm with 1.1 mm long optrodes from a single two inch glass wafer. The 9 × 9 UOA was too large for precise targeting of the upper layers of the cortex in smaller animals such as mice, so an array customization method was developed using Solidworks and off-the-shelf brain atlases to create 8 × 6 arrays 3.45 mm × 2.45 mm with 400 μm long optrodes. Stereotactic atlases were imported into Solidworks, splined, and lofted together to create a single 3D CAD model of a specific region of interest in the brain. Chronic and acute brain trauma showed excellent results for the 8 × 6 arrays in C57BL/6 wild-type mice (Mus musculus) and macaque monkey (Macaca fascicularis). Simulation, characterization, and radiometric testing of a single optrode of the 9 × 9 array was necessary to prove the ability to transmit light directly to specific tissue. Zemax optical design software was used to predict the light transmission capabilities, and then these results were compared to actual bench-top results. Insertion loss was both predicted and measured to be 3.7 dB. Power budgeting showed 9% of the light was lost at the interfaces of the UOA's backplane and tip in air, and 48% was lost through back-scattering, leaving 43% transmitting through the optrode with no measurable taper loss. Scanning electron microscopy showed small amounts of devitrification of the glass, and atomic force microscopy showed average surface roughness to be 13.5 nm and a root mean square roughness of 20.6 nm. The output beam was profiled in fluorescein dye with a total divergence angle of 63◦ with a cross over distance to adjacent beams at 255 μm

Nanocrystalline diamond-glass platform for the development of three-dimensional micro- and nanodevices

Low-cost and robust platforms are key for the development of next-generation 3D micro- and nanodevices. To fabricate such platforms, nanocrystalline diamond (NCD) is a highly appealing material due to its biocompatibility, robustness, and mechanical, electrical, electrochemical, and optical properties, while glass substrates with through vias are ideal interposers for 3D integration due to the excellent properties of glass. However, developing devices that comprise NCD films and through glass vias (TGVs) has rarely been attempted due to a lack of effective process strategies. In this work, a low-cost process - free of photolithography and transfer-printing - for fabricating arrays of TGVs that are sealed with suspended portions of an ultra-thin NCD film on one side is presented. These highly transparent structures may serve as a platform for the development of microwells for single-cell culture and analysis, 3D integrated devices such as microelectrodes, and quantum technologies. The process is demonstrated by fabricating TGVs that are sealed with an NCD film of thickness 175 nm and diameter 60 mu m. The technology described can be extended by replacing NCD with silicon nitride or silicon carbide, allowing for the development of complex heterogeneous structures on the small scale

Determination of the Young's modulus of pulsed laser deposited epitaxial PZT thin films

We determined the Young’s modulus of pulsed laser deposited epitaxially grown PbZr0.52Ti0.48O3 (PZT) thin films on microcantilevers by measuring the difference in cantilever resonance frequency before and after deposition. By carefully optimizing the accuracy of this technique, we were able to show that the Young’s modulus of PZT thin films deposited on silicon is dependent on the in-plane orientation, by using cantilevers oriented along the 1 1 0 and 1 0 0 silicon directions. Deposition of thin films on cantilevers affects their flexural rigidity and increases their mass, which results in a change in the resonance frequency. An analytical relation was developed to determine the effective Young’s modulus of the PZT thin films from the shift in the resonance frequency of the cantilevers, measured both before and after the deposition. In addition, the appropriate effective Young’s modulus valid for our cantilevers’ dimensions was used in the calculations that were determined by a combined analytical and finite-element (FE) simulations approach. We took extra care to eliminate the errors in the determination of the effective Young’s modulus of the PZT thin film, by accurately determining the dimensions of the cantilevers and by measuring many cantilevers of different lengths. Over-etching during the release of cantilevers from the handle wafer caused an undercut. Since this undercut cannot be avoided, the effective length was determined and used in the calculations. The Young’s modulus of PZT, deposited by pulsed laser deposition, was determined to be 103.0 GPa with a standard error of ± 1.4 GPa for the 1 1 0 crystal direction of silicon. For the 1 0 0 silicon direction, we measured 95.2 GPa with a standard error of ± 2.0 GPa

Study on Preparation and Reflow Process of Nano Glass Powder for MEMS Encapsulations

封装一直是MEMS器件的重难点，封装的好坏直接决定器件的成败。受成本、方便性、封装性能、工艺复杂程度、器件大小等诸多因素的影响，使用盖帽的圆片级封装成为一种明智、新颖和备受欢迎的方法，是MEMS器件封装的趋势。玻璃盖帽具有寄生电容小、和硅键合容易、绝热性能好等优点，是常用的封装盖帽。特别是高频RF传感器，玻璃盖帽因其良好的电学隔离作用，成为盖帽的最佳选择。然而玻璃盖帽的制作却非常困难。传统玻璃回流工艺是如今较好的一种玻璃盖帽制作方式，但仍然有很多不足，如抛光容易碎片、回流时间长、有最小线宽的限制、需要高真空阳极键合等。 本文以玻璃盖帽为出发点，研究了玻璃粉回流工艺的若干问题。为了获得纳米玻璃...Packaging which directly determines the success or failure of the device has always been the major difficulty in MEMS devices. Effected by many factors such as cost, convenience, package performance, process complexity, device size, wafer level packaging using a cap becomes a wise, novel and popular way, and it is the inevitable trend of MEMS package. Due to the advantages of small parasitic capac...学位：工学硕士院系专业：航空航天学院_机械制造及其自动化学号：1992014115287

Integrated silicon photonic packaging

Silicon photonics has garnered plenty of interests from both the academia and industry due to its high-speed transmission potential as well as sensing capability to complement silicon electronics. This has led to significant growth on the former, valuing at US$626.8M in 2017 and is expected to grow 3-fold to US$ 1,988.2M by 2023, based on data from MarketsandMarkets™. Silicon photonics’ huge potential has led to worldwide attention on fundamental research, photonic circuit designs and device fabrication technologies. However, as with silicon electronics in its early years, the silicon photonics industry today is extremely fragmented with various chip designs and layouts. Most silicon photonic devices fabricated are not able to reach the hand of consumers, due to a lack of information related to packaging design rules, components and processes. The importance of packaging technologies, which play a crucial role in turning photonic circuits and devices into the final product that end users can used in their daily lives, has been overlooked and understudied. This thesis aims to – 1. fill the missing gap by adapting existing electronics packaging techniques, 2. assess its scalability, 3. assess supply chain integration and finally 4. develop unique packaging approaches specifically for silicon photonics. The first section focused on high density packaging components and processes using University of California, Berkeley’s state-of-the-art silicon photonic MEMS optical switches as test devices. Three test vehicles were developed using (1) via-less ceramic and (2) spring-contacted electrical interposers for 2D integration and (3) through-glass-via electrical interposers for 2.5D heterogeneous integration. A high density (1) lidless fibre array and (2) a 2D optical interposer, which allows pitch-reduction of optical waveguides were also developed in this thesis. Together, these components demonstrated the world’s first silicon 2 photonic MEMS optical switch package and subsequently the highest density silicon photonic packaging components with 512 electrical I/Os and 272 optical I/Os. The second section then moved away from active optical coupling that was used in the former, investigating instead passive optical packaging concepts for the future. Two approaches were investigated - (1) grating-to-grating and (2) evanescent couplings. The former allows the development of pluggable packages, separating fibre coupling away from the device while the latter allows simultaneous optical and electrical packaging on a glass wafer in a single process. Lastly, the knowhow and concepts developed in this thesis were compiled into packaging design rules and subsequently introduced into H2020-MORPHIC, PIXAPP packaging training courses (as a trainer) and other packaging projects within the group