Chemical mechanical polishing (CMP) serves as an indispensable process for achieving global planarization in semiconductor manufacturing, especially as integrated circuit (IC) technology advances to sub-7 nm nodes, where atomic-level surface flatness becomes crucial. Silica abrasives, which account for over 90% of the abrasive market in advanced CMP processes, operate not through simple mechanical grinding but through a key "chemical-mechanical synergistic" mechanism: chemically softening the wafer surface, then mechanically removing the softened layer to expose a new surface, which is further softened and removed, repeating this cycle to produce a smooth wafer. Despite their prevalence, conventional silica abrasives still face challenges, including relatively low material removal rate (MRR), a tendency to agglomerate, leading to poor dispersion and surface defects, and limitations in achieving ultimate surface uniformity. Significant progress has been made to address these issues. Development has progressed from simple spherical particles to complex structural designs (such as mesoporous, hollow, and raspberry-shaped structures) to enhance slurry transport and mechanical action. Surface chemical modifications (e.g., using amino or polymer groups) can improve dispersion stability and reduce scratching. Furthermore, composites with other materials (e.g., ceria, polymers) and precise control of particle size distribution are key to enhancing performance. These innovative approaches have yielded significant performance gains. State-of-the-art slurries have demonstrated the ability to achieve surface roughness below 0.1 nm RMS. The development of silica abrasives is increasingly focused on sustainability and smart manufacturing. A prominent direction is the design of biodegradable abrasives that disintegrate after use, thereby simplifying post-chemical mechanical polishing (CMP) cleanup and minimizing environmental impact—an approach fully aligned with green manufacturing principles. This review systematically summarizes the progress of silica abrasives for CMP over the past 60 years. This summary provides theoretical insights and forward-looking strategies to overcome the current limitations of abrasive technology. We believe this review will be helpful in advancing the field of CMP abrasives towards next-generation semiconductor manufacturing.
The downscaling of logic devices has posed numerous engineering and manufacturing challenges in copper (Cu) interconnections. The primary failure modes of Cu filling defects are narrow top openings and discontinuous Cu seeds on sidewalls. This study investigates the influence and mechanism of layout on Cu filling defects. Dense line wires with uneven local layouts are prone to defects, which is attributed to the altered distribution of additives in electrochemical plating (ECP), leading to differences in bottom-up filling behavior. It is demonstrated that large-sized metal conductor regions adjacent to dense line wires adsorb substantial amounts of suppressor, resulting in sparse current density in these areas. Given the fixed total local current density, the sparseness of current density in adjacent regions inevitably diverts more current lines to the dense line wire areas. The excessive current density exceeds the local redistribution capacity of additives, causing premature sealing of trench tops and the formation of void defects. A low-current plating process significantly mitigates these defects but may compromise the protective capability of the Cu seed. Additionally, the perimeter density of the layout serves as an effective evaluation index.
Currently, the global 5G network, cloud computing, and data center industries are experiencing rapid development. The continuous growth of data center traffic has driven the vigorous progress in high-speed optical transceivers for optical interconnection within data centers. The electro-absorption modulated laser (EML), which is widely used in optical fiber communications, data centers, and high-speed data transmission systems, represents a high-performance photoelectric conversion device. Compared to traditional directly modulated lasers (DMLs), EMLs demonstrate lower frequency chirp and higher modulation bandwidth, enabling support for higher data rates and longer transmission distances. This article introduces the composition, working principles, manufacturing processes, and applications of EMLs. It reviews the progress on advanced indium phosphide (InP)-based EML devices from research institutions worldwide, while summarizing and comparing data transmission rates and key technical approaches across various studies.
The AC-electronic and dielectric properties of different phthalocyanine films (ZnPc, CuPc, FePc, and H2Pc) were investigated over a wide range of temperature. Both real and imaginary parts of the dielectric constant (ε=ε1-iε2) were found to be influenced by temperature and frequency. Qualitatively the behavior was the same for those compounds; however, the central atom, film thickness, and the electrode type play an important role in the variation of their values.The relaxation time, τ, was strongly frequency-dependent at all temperatures and low frequencies, while a weak dependency is observed at higher frequencies. The relaxation activation energy was derived from the slopes of the fitted lines of ln τ and the reciprocal of the temperature (1/T). The values of the activation energy were accounted for the hopping process at low temperatures, while a thermally activated conduction process was dominant at higher temperatures.The maximum barrier height, Wm, was found to be temperature and frequency dependent for all phthalocyanine compounds. The value Wm depends greatly on the nature of the central atom and electrode material type. The correlated barrier hopping model was found to be the appropriate mechanism to describe the charge carrier's transport in phthalocyanine films.
Although perovskite solar cells containing methylamine cation can show high power conversion efficiency, stability is a concern. Here, methylamine-free perovskite material CsxFA1–xPbI3 was synthesized by a one-step method. In addition, we incorporated smaller cadmium ions into mixed perovskite lattice to partially replace Pb ions to address the excessive internal strain in perovskite structure. We have found that the introduction of Cd can improve the crystallinity and the charge carrier lifetime of perovskite films. Consequently, a power conversion efficiency as high as 20.59% was achieved. More importantly, the devices retained 94% of their initial efficiency under 1200 h of continuous illumination.
The optical properties of polypyrrole (Ppy) thin films upon 2 MeV electron beam irradiation changes with different doses. The induced changes in the optical properties for Ppy thin films were studied in the visible range 300 to 800 nm at room temperature. The optical band gap of the pristine Ppy was found to be 2.19 eV and it decreases up to 1.97 eV for a 50 kGy dose of 2 MeV electron beam. The refractive index dispersion of the samples obeys the single oscillator model. The obtained results suggest that electron beam irradiation changes the optical parameters of Ppy thin films.
The continuous progress in thin film materials and devices has greatly promoted the development in the field of flexible electronics. As one of the most common thin film devices, thin film transistors (TFTs) are significant building blocks for flexible platforms. Flexible oxide-based TFTs are well compatible with flexible electronic systems due to low process temperature, high carrier mobility, and good uniformity. The present article is a review of the recent progress and major trends in the field of flexible oxide-based thin film transistors. First, an introduction of flexible electronics and flexible oxide-based thin film transistors is given. Next, we introduce oxide semiconductor materials and various flexible oxide-based TFTs classified by substrate materials including polymer plastics, paper sheets, metal foils, and flexible thin glass. Afterwards, applications of flexible oxide-based TFTs including bendable sensors, memories, circuits, and displays are presented. Finally, we give conclusions and a prospect for possible development trends.
Flexible and wearable optoelectronic devices have been developing to a new stage due to their unique capacity for the possibility of a variety of wearable intelligent electronics, including bendable smartphones, foldable touch screens and antennas, paper-like displays, and curved and flexible solid-state lighting devices. Before extensive commercial applications, some issues still have to be solved for flexible and wearable optoelectronic devices. In this regard, this review concludes the newly emerging flexible substrate materials, transparent conductive electrodes, device architectures and light manipulation methods. Examples of these components applied for various kinds of devices are also summarized. Finally, perspectives about the bright future of flexible and wearable electronic devices are proposed.
In a recent article, Chen et al. [Electrochimica Acta, 2014, 130: 279] presented their fabrication and characterization results on a graphene/n-Si solar cell where the Au nanoparticles were inserted in graphene to increase its optical and electrical properties. The higher efficiency of the device was attributed to increased conductivity of graphene after doping with Au nanoparticles. However, the knowledge in the field of Schottky diode solar cells relates this to increased band bending at the junction. Also, to explain the instability behaviour, they concluded that the growth of silicon oxide on the Si surface or oxygen adsorption on the window layer resulted in the device performance increasing initially and decreasing in the end. However, this instability seems to be due to variation in series resistance reduced at the beginning because of slightly lowered Fermi level and increased at the end by the self-compensation by deep in-diffusion of Au nanoparticles into n-Si layer. We also propose that inserting a very thin p-type layer at the junction will enhance the carrier collection and performance of this device.
