Silicon-on-quartz Research Articles

Silicon-on-quartz bonding based SPR chip

In this paper, an Otto coupling configuration based SPR chip is designed, simulated and fabricated using a silicon-on-quartz (SoQ) bonding process. The simulation of the SPR effect is conducted using COMSOL Multiphysics simulator (Altsoft Co.) using the designed chip dimensions, the optical constants are interpolated from data available in the literature. The size of the fabricated SPR chip is $$30\; \times \;30\; \times \;1 {\text{mm}}^{3}$$30×30×1mm3. Resonance angle and reflectance are measured to be 42.19° and 0.411°, respectively, using an automated reflectometer. Discrepancy between measurement and simulation results is discussed by optical constant of the gold layer used as a thin metal film. The SoQ bonding process is a feasible approach for implementation of Otto coupling configuration based SPR chips.

Enhanced Thermoelectric Efficiency of Si-Ni Nanocomposite Films Grown on SOI and SOQ Substrates

To improve the poor thermoelectric performance of Si, reduction of the high thermal conductivity k (~142 Wm–1K–1) is essential, and one of the effective methods to reduce the k is making Si nanostructures such as Si nanocrystals (NCs) [1, 2] and nanowires[3], where the k is dramatically reduced by enhancement of phonon scattering at the interfaces of the nanostructures. Recently, we developed semiconducting composite films of Si and Ni silicide NCs (Si-Ni nanocomposite film) deposited on SiO2 substrates [2]with the power factor of 1.9×10-3 W/mK2 , the thermal conductivity k of 4.4 W/mK, and the dimensionless figure of merit ZT of 0.13 for the B-doped (p-type ) nanocomposite film [2], which is much higher than that of bulk Si (ZT<0.01).In this paper, we demonstrate the further improvement of the thermoelectric performance of B doped Si-Ni nanocomposite films by growing them on silicon-on-insulator (SOI) or silicon-on-quartz (SOQ) substrates. The B doped Si-Ni nanocomposite films were synthesized from amorphous Si-Ni-B films deposited on the SOI or SOQ substrates at room temperature (RT) with Ar sputtering of the B doped Ni-Si target (Ni:Si=1:20, 2mol% B). The amorphous films were annealed at 800°C in N2gas ambient, leading to crystallization and the phase separation of the films. After this annealing , rapid annealing of 10 sec at 1200°C was carried out to activate the B atoms.In Fig.1, the ZT values are plotted against the k valuesof Si-Ni nanocomposite films on SOI, SOQ, SiO2 substrates [ 2], and Si nanocomposite by Bux et al. [1] at RT. We observed low k values (< 4 W/mK) of Si-Ni nanocomposite films on SOI and SOQ, which were similar k with Si-Ni nanocomposite film on SiO2, due to phonon scattering at interfaces on NCs. As seen, the ZTs (0.23-0.36) of the Si-Ni nanocomposite films on SOI and SOQ substrates were much higher than those of the Si-Ni nanocomposite films on SiO2 and the Si nanocomposite. We observed with cross-sectional transmission electron microscopy that Si NCs in Si-Ni composite films were epitaxially grown from thin Si crystal layers of SOI /SOQ substrates, leading to improvement of the crystal quality of Si NCs in the nanocomposite films and increase of the carrier conductivities, the Seebeck coefficients and the ZTs.This work was partly supported by ALCA-JST.[1] S. K. Bux, et al., Adv. Funct. Mater. 19, 2445 (2009). [2] N. Uchida et al., J. Appl. Phys. 114, 134311 (2013). [3] A. I. Hochbaum, et al., Nature 451,163 (2008).

Crystal direction dependence of quantum confinement effects of two-dimensional Si layers fabricated on silicon-on-quartz substrates: modulation of phonon spectra and energy band structures

We experimentally studied the crystal direction dependence of phonon confinement effects (PCEs) and bandgap (EG) modulation of a two-dimensional (2D) Si layer fabricated on (100) silicon-on-quartz (SOQ) wafers without a handle Si substrate. For the first time, by polarization Raman spectroscopy, in the case of Raman intensity spectra in the asymmetrical broadening region owing to the PCEs in the 2D Si layer, we demonstrated that the incident laser polarization direction dependence of the Raman intensity deviates from the Raman selection rule. However, a photoluminescence (PL) method shows that the EG expansion is isotropic in the 2D Si layer. On the other hand, the reflectivity of the 2D Si layer in UV region is also modulated. The reflectivity property modulation is possibly attributable to the energy band modulation in the 2D Si layer.

Low‐loss silicon‐on‐quartz (SoQ)‐based aperture‐coupled antenna on RF MEMS packaging platform

AbstractThis letter presents a micromachined aperture‐coupled antenna which improves antenna performances as well as simplifies a fabrication process. The SoQ (silicon‐on‐quartz) bonding and BCB (benzocyclobutene) adhesive bonding are employed for a radio frequency microelectro‐mechanical system (RF‐MEMS) packaging platform. The SoQ/BCB packaging platform makes the air cavity and the quartz substrate where the aperture‐coupled antenna is stacked. Therefore, radiation performances can be enhanced from low‐loss air/quartz substrates while a silicon substrate has almost no effects on radiation. Furthermore, the proposed method enables simultaneous integration of the antenna with the RF MEMS devices through a single packaging process. In this letter, the antenna is manufactured based on the proposed method and the fabrication process is carefully described. The s‐parameters and shear strength are measured to evaluate both of antenna and packaging performances. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 125–128, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24874

Effects of Eddy Current on Characteristics of Spiral Inductors on Silicon

We describe the effect of eddy currents flowing through a silicon substrate and a grounded metal plate on the characteristics of spiral inductors fabricated using complementary metal–oxide–semiconductor technology. The S-parameters of the spiral inductors on silicon-on-metal (SoM) and silicon-on-quartz (SoQ) are measured. The quality factor and inductance of the spiral inductor on SoM decrease as silicon substrate thickness decreases, because of an increase in the eddy current flowing through the metal plate. In the case of SoQ, the quality factor and inductance of the spiral inductor decrease as silicon substrate thickness decreases, because of a rapid increase in the eddy current flowing through the metal plate, if the distance between the inductor and the metal plate is shorter than the radius of the spiral inductor. Otherwise, the quality factor and inductance are almost constant for various substrate thicknesses, because of the small eddy current flowing through the metal plate.

Drive Current Enhancement in Silicon-on-Quartz MOSFETs

We proposed the advantages of MOSFETs fabricated on silicon-on-quartz (SOQ) wafers over MOSFETs on silicon-on-insulator (SOI) wafers. We demonstrated by device simulation that ionized acceptors under a buried oxide (BOX) layer are eliminated in an SOI MOSFET with a BOX layer that is thick enough in an SOQ MOSFET, and carriers in the channel are induced more effectively by the gate electric field in SOQ MOSFETs than in SOI MOSFETs. Additionally, we confirmed experimentally the enhancement of induced carriers and its resultant improvement of the subthreshold characteristics and transconductance characteristics in SOQ MOSFETs.

Characteristics of Transmission Lines on Silicon-on-Metal and Silicon-on-Quartz

In this paper, we describe the effect of silicon substrate thickness on the characteristics of transmission lines fabricated using complementary metal–oxide–semiconductor (CMOS) technology. The S-parameters of the transmission lines on silicon-on-metal (SoM) and silicon-on-quartz (SoQ) are measured. The inductance of a microstrip line on SoM decreases as silicon substrate thickness is reduced, while that on SoQ is nearly constant for various substrate thicknesses. This fact is explained by the magnetic energy of the electromagnetic wave stored in the microstrip lines. Moreover, the loss of the microstrip line on SoM decreases as substrate thickness is reduced owing to a decrease in dielectric loss. In contrast, the characteristics of coplanar waveguides on both SoM and SoQ are constant for various substrate thicknesses.

Surface Activation Using Remote Plasma for a New Wafer Bonding Route to Strained-Si

A pre-bonding remote plasma treatment is being used here to enable differential thermal (dT) bonding and heterogeneous wafer bonding of Si to Si and quartz at room temperature and at elevated temperature. The results presented here are part of an ongoing research, which if successful will yield Ge free strained-Si substrates. Various pre-bonding plasma treatments of wafers prior to room temperature and elevated temperature silicon on quartz (SOQ) and silicon on insulator (SOI) bonding are presented. Comparison of standard RCA surface activation versus remote plasma surface activation has been reported. Attention is focused on the results obtained by varying different plasma parameters - time, gas species, flow rate etc and their effect on the surface energy of the bonded pair. Defects introduced during bonding and annealing were detected using an in-situ IR camera and capture system and surface micro roughness measurements were made using AFM.

Smart-Cut ® technology: from 300 mm ultrathin SOI production to advanced engineered substrates

The Smart-Cut ® process, based on hydrogen implantation and wafer bonding, is a generic thin layer process transfer. Unibond ® SOI wafers are today in volume production, showing that splitting and bonding steps can be controlled, with high yields. Taking advantage of standard equipments flexibility, the process has been successfully scaled up to 300 mm. Most advanced 200 mm processes were successfully transferred to 300 mm, with wafers showing uniformity and defectivity results compatible with industry requirements for fully depleted device applications. The number of wafer solutions offered by the Smart-Cut ® technology is already much greater than just SOI. Strained silicon on insulator, silicon on quartz (SOQ), single crystal silicon layer on plastic supports, silicon carbide on insulator, germanium on insulator, multilayer SOI structures are just few examples of the potential of Smart Cut ® to engineer and design new substrates to answer the demands of the industry. A review of the progress achieved is given.