S. Beckx

Basic structures for photonic integrated circuits in Silicon-on-insulator

For the compact integration of photonic circuits, wavelength-scale structures with a high index contrast are a key requirement. We developed a fabrication process for these nanophotonic structures in Silicon-on-insulator using CMOS processing techniques based on deep UV lithography. We have fabricated both photonic wires and photonic crystal waveguides and show that, with the same fabrication technique, photonic wires have much less propagation loss than photonic crystal waveguides. Measurements show losses of 0.24dB/mm for photonic wires, and 7.5dB/mm for photonic crystal waveguides. To tackle the coupling to fiber, we studied and fabricated vertical fiber couplers with coupling efficiencies of over 21%. In addition, we demonstrate integrated compact spot-size converters with a mode-to-mode coupling efficiency of over 70%.

Compact wavelength router based on a Silicon-on-insulator arrayed waveguide grating pigtailed to a fiber array

We demonstrate a compact, fiber-pigtailed, 4-by-4 wavelength router in Silicon-on-insulator photonic wires, fabricated using CMOS processing methods. The core is an AWG with a 250GHz channel spacing and 1THz free spectral range, on a 425x155 microm(2) footprint. The insertion loss of the AWG was reduced to 3.5dB by applying a two-step processing technique. The crosstalk is -12dB. The device was pigtailed using vertical fiber couplers and an eight-fiber array connector.

Ultralow-loss 3-dB photonic crystal waveguide splitter

A photonic crystal waveguide splitter that exhibits ultralow-loss 3-dB splitting for TE-polarized light is fabricated in silicon-on-insulator material by use of deep UV lithography. The high performance is achieved by use of a Y junction, which is designed to ensure single-mode operation, and low-loss 60 degrees bends. Zero-loss 3-dB output is experimentally obtained in the range 1560-1585 nm. Results from three-dimensional finite-difference time-domain modeling with no adjustable parameters are found to be in excellent agreement with the experimental results.

Linear and Nonlinear Nanophotonic Devices Based on Silicon-on-Insulator Wire Waveguides

We review the basic linear and nonlinear properties of silicon-on-insulator photonic wire waveguides and their application to nanophotonic circuits. We give an overview of the performance and issues of basic circuit elements such as couplers and intersections and review the achievements in linear wavelength-selective elements, as well as nonlinear applications of wires and resonators for high-speed signal processing.

Evaluation of megasonic cleaning for sub-90-nm technologies

Cleaning of nanoparticles (< 50nm ) is becoming a major challenge in semiconductor manufacturing and the future use of traditional methods, such as megasonic cleaning, is questioned. In this paper the capability of megasonic cleaning to remove nanoparticles without inflicting damage to fragile structures is investigated. The role of dissolved gas in cleaning efficiency indicates that cavitation is the main cleaning mechanism. Consequently gas mass-balance analyses are needed to optimize the performance of cleaning tools. When gas is dissolved in the cleaning present tools can remove nanoparticles down to about 30 nm using dilute chemistries at low temperature. Ultimate performance is limited by cleaning uniformity, which depends on tool design and operation. However no tool reached the target of high particle removal efficiency andlow damage. Significantly lower damage could only be obtained by decreasing the power, at the cost of a lower cleaning efficiency for nanoparticles. The development of damage-free megasonic is discussed.

Gatestacks for scalable high-performance FinFETs

Excellent performance (995 muA/mum at Ioff=94 n A/mum and Vdd=lV) and short channel effect control are achieved for tall, narrow FinFETs without mobility enhancement. Near-ideal fin/gate profiles are achieved with standard 193 nm immersion lithography and dry etch. PVD TiN electrodes on Hf SiO dielectrics are shown to give improved NMOS performance over PEALD TiN whilst poorer conformality, for both dielectric and gate electrode, does not appear to impact scalability or performance. Excellent PMOS performance is achieved for both PEALD and PVD TiN. A new model for threshold voltage VT variability is shown to explain this dependence upon fin width and gate length.

Basic photonic wire components in silicon-on-insulator

We fabricated basic structures for photonic integrated circuits in silicon-on-insulator photonic wires using CMOS technology. We show low-loss bends and waveguide intersections, power splitters, MMIs and Mach-Zehnder interferometers.

CMP-less integration of fully Ni-silicided metal gates in FinFETs by simultaneous silicidation of the source, drain, and the gate using a novel dual hard mask approach

We demonstrate a novel CMP-less dual hard mask scheme for the integration of fully silicided gates in FinFETs by simultaneous silicidation of the gate, source and the drain. V/sub T/ of 0.18V and -0.2V are demonstrated for 50nm gate length NFET and PFET respectively. Competitive I/sub on/-I/sub off/ of 960uA/um-140nA/um for NFET and 620uA/um-100nA/um for PFET were obtained at V/sub D/=l .3V for an EOT of 1.8nm.

Wavelength-selective components in SOI photonic wires fabricated with deep UV lithography

We demonstrate both ring resonator drop filters and arrayed waveguide gratings in silicon-on-insulator photonic wires. The structures are fabricated in a CMOS line using deep UV lithography and dry etching processes. Waveguide losses are as low as 2.4 dB/cm for a 500 nm wide photonic wire, with excess bend losses of 0.03 dB/90/spl deg/ in a 3 /spl mu/m bend. Using grating fiber couplers for measurements, we show ring and racetrack resonators with a Q up to 12700 and an 8-channel arrayed waveguide grating with a footprint of about 0.1 mm/sup 2/, 3 nm channel spacing and -6 dB crosstalk between channels.

Silicon nanophotonic wire structures fabricated by 193nm optical lithography

We demonstrate the use of 193 nm optical lithography for fabricating nanophotonic wire structures on silicon-on-insulator (SOI) technology. We present fabrication and measurement result on wire devices. We report a propagation loss of 2.8 dB/cm for 450times220 nm photonic wire.