Bernd Tillack

High-Performance BiCMOS Technologies without Epitaxially-Buried Subcollectors and Deep Trenches

This paper describes the architecture of the BiCMOS processes highlighting the modular scheme for the integration of the bipolar modules into a common CMOS platform. HBT design issues associated with the implanted collector wells and the key set of electrical HBT parameters are presented as well

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A 0.13 µm SiGe BiCMOS technology for millimeter wave applications is presented. This technology features high-speed HBTs (f<inf>T</inf>=240 GHz, f<inf>max</inf>=330 GHz, BV<inf>CEO</inf>=1.7 V) along with high-voltage HBTs (f<inf>T</inf>=50 GHz, f<inf>max</inf>=130 GHz, BV<inf>CEO</inf>=3.7 V) integrated in a dual-gate, triple-well RF-CMOS process. Ring oscillator gate delays of 2.9 ps, low-noise amplifiers for 122 GHz, and LC oscillators for frequencies above 200 GHz are demonstrated.

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Back-end-of-line integrated 1 × μm2 TiN/HfO2/Ti/TiN MIM memory devices in a 0.25- μm complementary metal-oxide-semiconductor technology were built to investigate the conduction mechanism and the resistive switching behavior as a function of temperature. The temperature-dependent I- V characteristics in fresh devices are attributed to the Poole-Frenkel mechanism with an extracted trap energy level at φ ≈ 0.2 eV below the HfO2 conduction band. The trap level is associated with positively charged oxygen vacancies. The electroformed memory cells show a stable bipolar switching behavior in the temperature range from 213-413 K. The off -state current increases with temperature, whereas the on-state current can be described by a weak metallic behavior. Furthermore, the results suggest that the I-V cycling not only induces significant changes in the electrical properties of the MIM memory devices, i.e., the increase in the off-state current, but also stronger temperature dependence. The temperature effect on the on-state and off-state characteristics is modeled within the framework of the quantum point-contact model for dielectric breakdown using an effective temperature-dependent confinement potential.

SiGe BiCMOS Technology Featuring f

One of the main requirements for Si-based ultrasmall devices is atomic-order control of process technology. Here we show the concept of atomically controlled processing for group IV semiconductors based on atomic-order surface reaction control. By ultraclean low-pressure chemical vapor deposition using SiH4 and GeH4 gases, high-quality low-temperature epitaxial growth of Si, Ge, and Si1-xGex with atomically flat surfaces and interfaces on Si(100) is achieved, and atomic-order surface reaction processes on group IV semiconductor surface are formulated based on a Langmuir-type surface adsorption and reaction scheme. In in-situ doped Si1-xGex epitaxial growth on the (100) surface in a SiH4?GeH4?dopant (PH3, or B2H6 or SiH3CH3)?H2 gas mixture, the deposition rate, the Ge fraction and the dopant concentration are explained quantitatively assuming that the reactant gas adsorption/reaction depends on the surface site material and that the dopant incorporation in the grown film is determined by Henrys law. Self-limiting formation of 1?3 atomic layers of group IV or related atoms in the thermal adsorption and reaction of hydride gases on Si(100) and Ge(100) is generalized based on the Langmuir-type model. Si or SiGe epitaxial growth over N, P or B layer already-formed on Si(100) or SiGe(100) surface is achieved. Furthermore, the capability of atomically controlled processing for advanced devices is demonstrated. These results open the way to atomically controlled technology for ultralarge-scale integrations.

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The conduction process as well as the unipolar resistive switching behavior of Au∕HfO2∕TiN metal-insulator-metal structures were investigated for future nonvolatile memory applications. With current-voltage measurements performed at different temperatures (200–400K), the Poole–Frenkel effect as conduction process was identified. In particular, we extracted a trap energy level at ϕt=0.35±0.05eV below the HfO2 conduction band to which a microscopic origin is tentatively assigned. From current-voltage measurements of Au∕HfO2∕TiN structures, low-power (as low as 120μW) resistive switching was observed. The required forming process is shown to be an energy-induced phenomenon. The characteristics include electric pulse-induced resistive switching by applying pulses up to 100μs and a retention time upon continuous nondestructive readout of more than 104s.

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In this work we study, using experiments and theoretical modeling, the mechanical and optical properties of tensile strained Ge microstructures directly fabricated in a state-of-the art complementary metal-oxide-semiconductor fabrication line, using fully qualified materials and methods. We show that these microstructures can be used as active lasing materials in mm-long Fabry-Perot cavities, taking advantage of strain-enhanced direct band gap recombination. The results of our study can be realistically applied to the fabrication of a prototype platform for monolithic integration of near infrared laser sources for silicon photonics.

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We have analyzed the strain distribution and the photoluminescence in Ge microstructures fabricated by means of a Si-CMOS compatible method. The tensile strain in the Ge microstructures is obtained by using a SiN stressor layer. Different shapes of microstructure, allowing the Ge layers to freely expand into one, two, or three dimensions, resulted in different strain distribution profiles. Maximal equivalent biaxial tensile strain values up to ∼0.8% have been measured. Room temperature photoluminescence emission has been observed and attributed to direct-band gap recombination spectrally shifted by tensile strain.

of 240/330 GHz and Gate Delays Below 3 ps

Phase regeneration of differential phase-shift keying (DPSK) signals is demonstrated using a silicon waveguide as nonlinear medium for the first time. A p-i-n junction across the waveguide enables decreasing the nonlinear losses introduced by free-carrier absorption (FCA), thus allowing phase-sensitive extinction ratios as high as 20 dB to be reached under continuous-wave (CW) pumping operation. Furthermore the regeneration properties are investigated under dynamic operation for a 10-Gb/s DPSK signal degraded by phase noise, showing receiver sensitivity improvements above 14 dB. Different phase noise frequencies and amplitudes are examined, resulting in an improvement of the performance of the regenerated signal in all the considered cases.

Impact of Temperature on the Resistive Switching Behavior of Embedded

In this paper we present four-wave mixing (FWM) based parametric conversion experiments in p-i-n diode assisted silicon-on-insulator (SOI) nano-rib waveguides using continuous-wave (CW) light around 1550 nm wavelength. Using a reverse biased p-i-n waveguide diode we observe an increase of the wavelength conversion efficiency of more than 4.5 dB compared to low loss nano-rib waveguides without p-i-n junction, achieving a peak efficiency of -1 dB. Conversion efficiency improves also by more than 7 dB compared to previously reported experiments deploying 1.5 µm SOI waveguides with p-i-n structure. To the best of our knowledge, the observed peak conversion efficiency of -1dB is the highest CW efficiency in SOI reported so far.

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One of the main requirements for ultra-large-scale integrations (ULSIs) is atomic-order control of process technology. Our concept of atomically controlled processing is based on atomic-order surface reaction control by CVD. By ultraclean low-pressure CVD using SiH4 and GeH4 gases, high-quality low-temperature epitaxial growth of Si1−xGex (100) (x=0–1) with atomically flat surfaces and interfaces on Si(100) is achieved. Self-limiting formation of 1–3 atomic layers of group IV or related atoms in the thermal adsorption and reaction of hydride gases on Si1-xGex (100) are generalized based on the Langmuir-type model. By the Si epitaxial growth on top of the material already-formed on Si(100), N, B and C atoms are confined within about a 1 nm thick layer. In Si cap layer growth on the P atomic layer formed on Si1−xGex (100), segregation of P atoms is suppressed by using Si2H6 instead of SiH4 at a low temperature of 450 °C. Heavy C atomic-layer doping suppresses strain relaxation as well as intermixing between Si and Ge at the Si1−xGex/Si heterointerface. It is confirmed that higher carrier concentration and higher carrier mobility are achieved by atomic-layer doping. These results open the way to atomically controlled technology for ULSIs.