The advanced fin-shaped field-effect transistor (FinFET) technology offers higher integration density and stronger channel control capabilities, however, more complex process effects are also introduced which have significant influence on device performance. To address these issues, we complete a design-technology co-optimization (DTCO) focused on FinFET, including both process-induced effect during gate formation and corresponding digital unit optimization design. The 14 nm FinFET complementary metal oxide semiconductor (CMOS) technology is used to illustrate the sensitivity of transistor performance to process-induced effect, specifically the poly pitch effect (PPE) and cut poly effect (CPE). Predictive technology computer aided design (TCAD) simulations have been carried out to evaluate the transistor performance in advance. Based on the results, optimizations in digital unit design is proposed. Fall delay of the digital unit inverter is decreased by 0.7%, and the rise delay is decreased by 2.1%. For multiple selector (MUX2NV), the delay decreases by 4.64% for rise and 3.56% for drop, respectively.
In this paper, the ESD discharge capability of GGNMOS (gate grounded NMOS) device in the radiation-hardened 0.18 μm bulk silicon CMOS process (Rad-Hard by Process: RHBP) is optimized by layout and ion implantation design. The effects of gate length, DCGS and ESD ion implantation of GGNMOS on discharge current density and lattice temperature are studied by TCAD and device simulation. The size of DCGS, multi finger number and single finger width of ESD verification structures are designed, and the discharge capacity and efficiency of GGNMOS devices in ESD are characterized by TLP test technology. Finally, the optimized GGNMOS is verified on the DSP circuit, and its ESD performance is over 3500 V in HBM mode.
Magnetic tunnel junction (MTJ) based spin transfer torque magnetic random access memory (STT-MRAM) has been gaining tremendous momentum in high performance microcontroller (MCU) applications. As eFlash-replacement type MRAM approaches mass production, there is an increasing demand for non-volatile RAM (nvRAM) technologies that offer fast write speed and high endurance. In this work, we demonstrate highly reliable 4 Mb nvRAM type MRAM suitable for industry and auto grade-1 applications. This nvRAM features retention over 10 years at 125 °C, endurance of 1 × 1012 cycles with 20 ns write speed, making it ideal for applications requiring both high speed and broad temperature ranges. By employing innovative MTJ materials, process engineering, and a co-optimization of process and design, reliable read and write performance across the full temperature range between −40 to 125 °C, and array yield that meets sub-1 ppm error rate was significantly improved from 0 to above 95%, a concrete step toward applications.
Semiconductor quantum dots are leading candidates for the on-demand generation of single photons and entangled photon pairs. High photon quality and indistinguishability of photons from different sources are critical for quantum information applications. The inability to grow perfectly identical quantum dots with ideal optical properties necessitates the application of post-growth tuning techniques via e.g. temperature, electric, magnetic or strain fields. In this review, we summarize the state-of-the-art and highlight the advantages of strain tunable non-classical photon sources based on epitaxial quantum dots. Using piezoelectric crystals like PMN-PT, the wavelength of single photons and entangled photon pairs emitted by InGaAs/GaAs quantum dots can be tuned reversibly. Combining with quantum light-emitting diodes simultaneously allows for electrical triggering and the tuning of wavelength or exciton fine structure. Emission from light hole exciton can be tuned, and quantum dot containing nanostructure such as nanowires have been piezo-integrated. To ensure the indistinguishability of photons from distant emitters, the wavelength drift caused by piezo creep can be compensated by frequency feedback, which is verified by two-photon interference with photons from two stabilized sources. Therefore, strain tuning proves to be a flexible and reliable tool for the development of scalable quantum dots-based non-classical photon sources.
Due to the remarkable growth rate compared to another growth methods for gallium nitride (GaN) growth, hydride vapor phase epitaxy (HVPE) is now the only method for mass product GaN substrates. In this review, commercial HVPE systems and the GaN crystals grown by them are demonstrated. This article also illustrates some innovative attempts to develop homebuilt HVPE systems. Finally, the prospects for the further development of HVPE for GaN crystal growth in the future are also discussed.
Two-dimensional materials have shown great application potential in high-performance electronic devices because they are ultrathin, have an ultra-large specific surface area, high carrier mobility, efficient channel current regulation, and extraordinary integration. In addition to graphene, other types of 2D nanomaterials have also been studied and applied in photodetectors, solar cells, energy storage devices, and so on. Bi2O2Se is an emerging 2D semiconductor material with very high electron mobility, modest bandgap, near-ideal subthreshold swing, and excellent thermal and chemical stability. Even in a monolayer structure, Bi2O2Se has still exhibited efficient light absorption. In this mini review, the latest main research progresses on the preparation methods, electric structure, and the optical, mechanical, and thermoelectric properties of Bi2O2Se are summarized. The wide rang of applications in electronics and photoelectronic devices are then reviewed. This review concludes with a discussion of the existing open questions/challenges and future prospects for Bi2O2Se.
The effects of cure temperature history on the stability of hinged structure poly (4, 4-oxydiphenylene pyromellitimide) (PMDA-ODA) polyimide were studied by dynamic mechanical analysis. The polyimide films were cured under different curing conditions and peeled off by substrate etching. It was found that a proper cure time and temperature ramp rate improves the stability in terms of higher glass transition temperature. Ninety minutes at 375℃ or 200℃ is a beneficial high glass transition temperature. The temperature ramp rate should be between 2℃/min and 10℃/min, which is neither too high nor too low.
β-Ga2O3 is an ultra-wide band-gap semiconductor with promising applications in UV optical detectors, Schottky barrier diodes, field-effect transistors and substrates for light-emitting diodes. However, the preparation of large β-Ga2O3 crystals is undeveloped and many properties of this material have not been discovered yet. In this work, 2-inch β-Ga2O3 single crystals were grown by using an edge-defined film-fed growth method. The high quality of the crystal has been proved by high-resolution X-ray diffraction with 19.06 arcsec of the full width at half maximum. The electrical properties and optical properties of both the unintentionally doped and Si-doped β-Ga2O3 crystals were investigated systematically.
For the non-stop demands for a better and smarter society, the number of electronic devices keeps increasing exponentially; and the computation power, communication data rate, smart sensing capability and intelligence are always not enough. Hardware supports software, while the integrated circuit (IC) is the core of hardware. In this long review paper, we summarize and discuss recent trending IC design directions and challenges, and try to give the readers big/cool pictures on each selected small/hot topics. We divide the trends into the following six categories, namely, 1) machine learning and artificial intelligence (AI) chips, 2) communication ICs, 3) data converters, 4) power converters, 5) imagers and range sensors, 6) emerging directions. Hope you find this paper useful for your future research and works.
