International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

"Extreme environments" represents an important niche market for electronics and spans the operation of electronic components in surroundings lying outside the domain of conventional commercial, or even military, specifications. Such extreme environments would include, for instance, operation to very low temperatures (e.g., to 77 K or even 4.2 K), operation at very high temperatures (e.g., to 200/spl deg/C or even 300/spl deg/C), and operation in a radiation-rich environment (e.g., space). We argue that the unique bandgap-engineered features of silicon-germanium heterojunction bipolar transistors offer great potential to simultaneously satisfy all three extreme environment applications, potentially with little or no process modification, ultimately providing compelling cost advantages at the IC and system level.

On the Potential of SiGe HBTs for Extreme Environment Electronics

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.

Impact of Temperature on the Resistive Switching Behavior of Embedded $\hbox{HfO}_{2}$ -Based RRAM Devices

Lignin from biomass can become a sustainable source of aromatic compounds. Its depolymerization can be accomplished through hydrogenolysis, although the development of catalysts based on cheap and abundant metals is lacking. Herein, a sustainable composite based on titanium nitride and nickel is synthesized and employed as catalyst for the hydrogenolysis of aryl ethers as models for lignin. The catalytic activity of the new material during hydrogenation reactions is proven to be superior to that of either component alone. In particular, different aryl ethers could be efficiently converted under relatively mild conditions into aromatic compounds and cycloalkanes within minutes.

Titanium nitride-nickel nanocomposite as heterogeneous catalyst for the hydrogenolysis of aryl ethers

Innovations in relevant micro-contact areas are highlighted, these include, design, contact resistance modeling, contact materials, performance and reliability. For each area the basic theory and relevant innovations are explored. A brief comparison of actuation methods is provided to show why electrostatic actuation is most commonly used by radio frequency microelectromechanical systems designers. An examination of the important characteristics of the contact interface such as modeling and material choice is discussed. Micro-contact resistance models based on plastic, elastic-plastic and elastic deformations are reviewed. Much of the modeling for metal contact micro-switches centers around contact area and surface roughness. Surface roughness and its effect on contact area is stressed when considering micro-contact resistance modeling. Finite element models and various approaches for describing surface roughness are compared. Different contact materials to include gold, gold alloys, carbon nanotubes, composite gold-carbon nanotubes, ruthenium, ruthenium oxide, as well as tungsten have been shown to enhance contact performance and reliability with distinct trade offs for each. Finally, a review of physical and electrical failure modes witnessed by researchers are detailed and examined.

/pdf/a-review-of-micro-contact-physics-for-microelectromechanical-4z1vzxhmv2.pdf

A review of micro-contact physics for microelectromechanical systems (MEMS) metal contact switches

We demonstrate for the first time the embedded integration of a Radio Frequency Microelectromechanical Systems (RF-MEMS) capacitive switch for mm-wave integrated circuits in a BiCMOS Back-end-of-line (BEOL). The switch shows state-of-the-art performance parameters. The “off” to “on” capacitance ratio is 1∶10 providing excellent isolation in the mm-wave frequency range. Insertion loss and isolation are found to fall below 1.65dB and to exceed 15dB, respectively, in the frequency range of 60GHz to 110GHz. Feasibility of switch integration into single chip RF designs is demonstrated for a dual-band voltage controlled oscillator (VCO). No performance degradation was observed after ten billion hot-switching cycles.

BEOL embedded RF-MEMS switch for mm-wave applications

A standard complementary metal-oxide-semiconductor (CMOS) process is successfully modified to encompass the preparation of suspended TiN membranes of only 50 nm thickness from one of the metal layer stacks of the back-end flow. The layers’ elastomechanical constants are determined with high precision by laser Doppler vibrometry. Residual stress gradients are compensated and a state of moderate tensile strain is introduced into the membranes. Test systems of TiN beams and bridges operating in a capacitive coupling scheme are optimized for the low voltage range attainable with CMOS devices. TiN actuators are particularly suited for applications in biotechnology like sensing of pressure or viscosity in microfluidic devices due to their high corrosion resistance in liquid electrolyte surroundings. The established inclusion of the process in a CMOS pilot line enables the production of cheap and monolithically integrated microelectromechanical systems (MEMS) and bio-microelectromechanical systems (BioMEMS) devices.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/adfm.201002062

Ultrathin TiN Membranes as a Technology Platform for CMOS‐Integrated MEMS and BioMEMS Devices

The use of the dominant CMOS (complementary metal–oxide–semiconductor) process technology in perspective bioelectronic applications imposes severe restrictions on the materials used with respect to their stability in aqueous solutions with high concentrations of electrolytes. We report the results of a comparative study of Al:Cu, CoSi2 and TiN metal layers that were prepared within a regular CMOS process and characterized by depth-profiling with X-ray photoelectron spectroscopy (XPS) in order to determine chemical composition and contaminants. The corrosion caused by isotonic NaCl solution was investigated and the most pronounced corrosion resistance was observed for TiN layers showing only negligible conductivity degradation when exposed to high concentration of electrolytes at elevated temperature for a time span of days. In addition, TiN layer electrodes turned out to be stable in an electrochemical cell over a large potential range and a wide pH range. No electrocatalytic activity for the conversion of hexacyanoferrate or catechol has been found. It is concluded that from the different metal layers available in CMOS processing, TiN layers are best suited for biomedical electrode applications.

/pdf/corrosion-resistant-metal-layers-from-a-cmos-process-for-3vaiq9mohv.pdf

Corrosion-resistant metal layers from a CMOS process for bioelectronic applications

We demonstrate a novel back-side processed, back to front self-aligned BiCMOS embedded RF-MEMS switch for the 90 to 140GHz frequency band. The switch integration is very simple, adding only one mask step to the underlying high-performance BiCMOS process. Moreover, it offers low cost, wafer level packaging. The insertion loss of the switch is less than 0.5dB up to 140GHz, and isolation is better than 15dB in the frequency range of 90 to 140GHz. The switch-on time is measured as 10µs. No performance degradation was observed after 5 billion cold switching cycles demonstrating the high reliability of the switch. An on-chip charge-pump (CP) circuit is realized using enhanced PMOS transistor to excite the switch with an output voltage of up to 50V and a rise time of 2µs.

BiCMOS embedded RF-MEMS switch for above 90 GHz applications using backside integration technique

We will describe the first modular integration of a SiGe:C heterojunction bipolar transistor (SiGe:C HBTs) into a conventional 025 /spl mu/m, epi-free CMOS platform The high temperature stability of base doping profiles in SiGe:C HBTs and an optimized collector linkage have allowed the modular integration of an npn device with f/sub T//f/sub max/ of 55/90 GHz into two variants of a conventional epi-free 025 /spl mu/m CMOS platform In both cases, the original CMOS steps and the electrical parameters of the CMOS devices remain essentially unchanged Yield and electrical characteristics of the integrated SiGe:C HBT are shown to be the same as those from a bipolar-only process

K.-E. Ehwald

Papers

BEOL embedded RF-MEMS switch for mm-wave applications

Ultrathin TiN Membranes as a Technology Platform for CMOS‐Integrated MEMS and BioMEMS Devices

Corrosion-resistant metal layers from a CMOS process for bioelectronic applications

BiCMOS embedded RF-MEMS switch for above 90 GHz applications using backside integration technique

Modular integration of high-performance SiGe:C HBTs in a deep submicron, epi-free CMOS process