High-Performance Al–Sn–Zn–In–O Thin-Film Transistors: Impact of Passivation Layer on Device Stability

We fabricated high-performance thin-film transistors (TFTs) with an amorphous-Al–Sn–Zn–In–O (a-AT-ZIO) channel deposited by cosputtering using a dual Al–Zn–O and In–Sn–O target. The fabricated AT-ZIO TFTs, which feature a bottom-gate and bottom-contact configuration, exhibited a high field-effect mobility of 31.9 $ hbox{cm}^{2}/hbox{V}cdothbox{s}$, an excellent subthreshold gate swing of 0.07 V/decade, and a high $I_{{rm on}/{rm off}}$ ratio of $≫hbox{10}^{9}$, even below the process temperature of 250 $^{circ}hbox{C}$. In addition, we demonstrated that the temperature and bias-induced stability of the bottom-gate TFT structure can significantly be improved by adopting a suitable passivation layer of atomic-layer-deposition-derived $hbox{Al}_{2} hbox{O}_{3}$ thin film.      

半导体混合加工制程的虚拟量测方法

为提高经济效应,半导体加工制程变得越来越复杂,生产线上同时有不同规格的产品在混合加工,能够同时预测这些规格晶圆的最终品质对提高晶圆的生产良率有着重要的意义。本文针对这种混合制程,提出一种虚拟量测算法,在统计回归的基础上,找出影响制程的关键变量,考虑不同规格晶圆的产品效应,利用共变异数分析算法辨识出虚拟量测模型,线上测试结果表明,本文算法不仅可以精确的预测待加工晶圆的线宽,而且可以用于半导体加工制程晶圆的故障侦测。     

Characterization of Fluxing and Hybrid Underfills with Micro‐encapsulated Catalyst for Long Pot Life

For the fine‐pitch application of flip‐chip bonding with semiconductor packaging, fluxing and hybrid underfills were developed. A micro‐encapsulated catalyst was adopted to control the chemical reaction at room and processing temperatures. From the experiments with a differential scanning calorimetry and viscometer, the chemical reaction and viscosity changes were quantitatively characterized, and the optimum type and amount of micro‐encapsulated catalyst were determined to obtain the best pot life from a commercial viewpoint. It is expected that fluxing and hybrid underfills will be applied to fine‐pitch flip‐chip bonding processes and be highly reliable.     

New two-inductor boost converter with auxiliary transformer

A new, two-inductor, two-switch boost converter topology and its variations suitable for applications with a large difference between the input and output voltage are described. The output voltage regulation of the proposed converters is achieved in a wide load and input-voltage range with constant-frequency control by employing an auxiliary transformer that couples the current paths of the two boost inductors.     

Transmission of block turbo coded digital audio over FM-SCA

In this paper, an efficient coded scheme for transmitting digital audio over the existing FM channel, by multiplexing it with the baseband FM signal, is described. Transmission of multiplexed signals in the FM baseband called FM-SCA (subsidiary communications authorization) has been previously used for low quality analog content and some low rate digital content. The investigated scheme opens up the possibility of achieving CD quality audio over FM-SCA by enabling high bitrate transmission using MPEG-I layer 3 and MPEG-AAC audio coding for the digital audio. These schemes provide CD quality audio at or below 128 kbps, MPEG-AAC being able to do so at rates as low as 96 kbps. Block turbo codes (BTC), which offer near Shannon's limit performance with relatively low hardware complexity requirements, provide the error protection. Block turbo codes have been shown to be particularly effective for high coding rates. The system uses OFDM in conjunction with 8PSK/16PSK to modulate the digital bitstream and fit it in the 44 kHz (54 to 98 kHz) band available in the FM baseband. Simulation results show an optimal system configuration for digital audio transmission in FM-SCA.     

A dry-patterned Cu(Mg) alloy film as a gate electrode in a thin-film transistor liquid crystal display

The annealing of a Cu(4.5at.%Mg)/SiO₂/Si structure in ambient O₂ at 10 mtorr and 300–500°C allows for the out-diffusion of the Mg to the Cu surface, forming a thin MgO (15 nm) layer on the surface. The surface MgO layer was patterned and successfully served as a hard mask for the subsequent dry etching of the underlying Mg-depleted Cu films using an O₂ plasma and hexafluoroacetylacetone (H(hfac)) chemistry. The resultant MgO/Cu structure, with a taper slope of about 30°, shows the feasibility of dry etching of Cu(Mg) alloy films using a surface MgO mask scheme. A dry-etched Cu(4.5at.%Mg) gate a-Si:H thin-film transistor (TFT) has a field-effect mobility of 0.86 cm²/Vs, a subthreshold swing of 1.08 V/dec, and a threshold voltage of 5.7 V. A novel process for the dry etching of Cu(Mg) alloy films that eliminates the use of a hard mask, such as Ti, and results in a reduction in the process steps is reported for the first time in this work.     

Enhanced Optical Properties and Stability of CsPbBr3 Nanocrystals Through Nickel Doping

To improve the quantum efficiency and stability of perovskite quantum dots, the structural and optical properties are optimized by varying the concentration of Ni doping in CsPbBr₃ perovskite nanocrystals (PNCs). As Ni doping is gradually added, a blue shift is observed at the photoluminescence (PL) spectra. Ni-doped PNCs exhibit stronger light emission, higher quantum efficiency, and longer lifetimes than undoped PNCs. The doped divalent element acts as a defect in the perovskite structure, reducing the recombination rate of electrons and holes. A stability test is used to assess the susceptibility of the perovskite to light and moisture. For ultra-violet light irradiation, the PL intensity of undoped PNCs decreases by 70%, whereas that of Ni-doped PNCs decreases by 18%. In the water addition experiment, the PL intensity of Ni-doped PNCs is three times that of undoped PNCs. For CsPbBr₃ and Ni:CsPbBr₃ PNCs, a light emitting diode is fabricated by spin-coating. The efficiency of Ni:CsPbBr₃ exceeds that of CsPbBr₃ PNCs, and the results significantly differ based on the ratio. A maximum luminance of 833 cd m^–2 is obtained at optimum efficiency (0.3 cd A^–1). Therefore, Ni-doped PNCs are expected to contribute to future performance improvements in display devices.     

Retina-Inspired Structurally Tunable Synaptic Perovskite Nanocones

Artificial photonic synapses with morphologically controlled photoreception, allowing for area-dependent tunable light reception as well as information storage and learning, have potential for application in emerging photo-interactive neuro-computing technologies. Herein, an artificially intelligent (AI) photonic synapse with area-density-tunable perovskite nano-cone arrays templated in a self-assembled block copolymer (BCP) is presented, which is based on a field effect transistor with a floating gate of photoreceptive perovskite crystal arrays preferentially synthesized in a micro-phase-segregated BCP film. These arrays are capable of electric charge (de)trapping and photo-excited charge generation, and they exhibit versatile synaptic functions of the nervous system, including paired-pulse facilitation and long-term potentiation, with excellent reliability. The area-density variable perovskite floating gate developed by off-centered spin coating process allows for emulating the human retina with a position-dependent spatial distribution of cones. 60 × 12 arrays of the developed synapse devices exhibit position-dependent dual functions of receptor and synapse. They are AI and exhibit a pattern recognition accuracy up to ≈90% when examined using the Modified National Institute of Standards and Technology handwritten digit pattern recognition test.     

Submicron-meter tunneling field-effect poly-Si thin-film transistors with a thinned channel layer

Submicron-meter poly-Si tunneling-effect thin-film transistor (TFT) devices with a thinned channel layer have been investigated. With reducing the gate length to be shorter than 1 μm, the poly-Si TFT device with conventional MOSFET structure is considerably degraded. The tunneling field-effect transistor (TFET) structure can be employed to alleviate the short channel effect, thus largely suppressing the off-state leakage. However, for a poly-Si channel layer of 100 nm thickness, the TFET structure causes a small on-state current, which may not provide well sufficient driving current. By reducing the channel layer thickness to be 20 nm, the on-state current for the TFET structure can be largely increased, due to the enhanced bending of energy band for a thinned channel layer. As a result, for the TFET poly-Si TFTs at a gate bias of 5 V and a drain bias of 3 V, a 20-nm channel layer leads to an on-state current of about 1 order larger than that by a 100-nm channel layer, while still keeping an off-state leakage smaller than 0.1 pA/μm. Accordingly, the submicron-meter TFET poly-Si TFT devices with a thinned channel layer would show good feasibility for implementing high packing density of poly-Si TFT devices.