Hong Dong

Diamond is an ideal semiconductor for high‐temperature, high‐voltage applications due to its wide band gap, high carrier mobility, and high thermal conductivity. Diamond Schottky barrier diodes (SBDs) have been intensively developed; however, their thermal stability has not been explored comprehensively. Considering that the diamond/metal interface is one key factor affecting the thermal stability, in this work, we employed tantalum (Ta)/oxygen‐terminated (O‐) diamond system and investigated the impact of annealing temperature (300°C, 600°C, 900°C, and 1200°C) on chemical and structural evolution of the Ta/O‐diamond interface under low‐oxygen ambient. Angle‐resolved X‐ray photoelectron spectroscopy (ARXPS) and atomic force microscopy (AFM) were performed to examine the interface reactions and surface morphologies. Furthermore, the possible mechanism of the interface evolution under low‐oxygen ambient was discussed. This work provides insights into understanding the interface evolution and thus the thermal stability Ta/O‐diamond.

Post-Moore nanoscale devices are driving the next wave of semiconductor advancement through three-dimensional architectures and material innovation. However, the shrinking source/drain contact area has made metal–semiconductor contact resistivity (ρc) a critical performance bottleneck. Conventional heavy doping techniques can no longer meet the stringent ρc requirement (<10−9 Ω cm2) for advanced technology nodes. Various strategies have been adopted to reduce it such as inserted silicide. However, ρc is typically limited to the range of 10−4–10−6 Ω cm2. Up until now, the mechanism behind these strategies is highly controversial. In this review, we comprehensively explain the underlying physical mechanisms governing ρc from the perspectives of Schottky barrier height and Fermi level pinning. Then, an analysis of state-of-the-art approaches for ρc reduction is reviewed, involving interface modification and oxide interlayer integration toward conventional semiconductor and advanced two-dimensional-based semiconductor. Finally, we discuss remaining challenges and proposing synergistic strategies on future research directions for achieving low contact resistivity in post-Moore nanoscale devices.

The electrochemical co-reduction of carbon dioxide (CO₂) and nitrate (NO₃ ⁻) to urea presents a sustainable strategy to alleviate the ecological and food crisis. However, the current urea electrosynthesis faces low selectivity issues due to the high energy barrier of C–N coupling, as well as the unbalanced supply of key intermediates. Herein, we report that a Au-doped Cu bimetallic catalyst effectively balances the supply of C-containing and N-containing intermediates, thereby enhancing urea selectivity. In situ Raman spectroscopy and density functional theory calculations demonstrate that doping Au into Cu enhances the surface coverage of the *CO intermediate and optimizes the adsorption energy of *NO, thereby lowering the energy barrier of C–N coupling from 0.44 eV on the Cu surface to 0.15 eV on the Cu–Au surface. Meanwhile, this doping engineering also suppresses the reactions competing with urea electrosynthesis. As a result, the Cu–Au catalyst achieves a urea faradaic efficiency of 67.81% and a yield rate of 49.34 μmol cm⁻² h⁻¹ at −0.4 V versus the reversible hydrogen electrode.

The metal–semiconductor contact resistivity has become a severe challenge for three-dimensional (3D) integration. In this work, starting from the physical origin, we propose that the charge redistribution is an effective strategy for decreasing Schottky barrier height (SBH), subsequently leading to a reduction in contact resistivity. Guided by this perspective, first-principles calculations are utilized to investigate the effect of a series of metal dopants on the SBH in the NiSi/Si system. The ΦBe values of NiSi/Si can be reduced to 0.27, 0.28, and 0.22 eV in Sc, Ti, and Zr doped systems, respectively. Especially for the Zr dopant, it can achieve ultra-low contact resistivity of 2.30 × 10−9 Ω cm2, which can be ascribed to the dominant charge redistribution effect. In contrast, high electronegativity dopants like Au and Ir increase ΦBe. Dopant diffusion and concentration effects are also examined, demonstrating the feasibility of this approach. This work provides a useful theoretical guidance in reducing contact resistivity for 3D integration.

Complementary field-effect transistor technology enhances integration density and reduces power consumption by vertically stacking n-MOS and p-MOS transistors. However, the three-dimensional (3D) architecture poses challenges in threshold voltage control when depositing metal with distinct work function (WF) for the gates. Using first-principles calculations, we explore wide-range WF modulation (3.20–5.25 eV) of defective TiN widely used in industry for 3D integration, enabling its application for both n- and p-MOS gates. Compared with bulk defects, WF is strongly affected by the surface defect types and their concentrations. Surface N adsorption can increase TiN WF from 4.73 to 5.25 eV when the concentration is within 12.5%–62.5%. In contrast, surface Ti vacancies can reduce the WF to 3.20 eV at a concentration of 62.5%. In addition, the stress effect indicates that WF increases under compressive stress and conversely for tensile stress. The above phenomenon can be attributed to the charge transfer and charge redistribution by different defects. This WF modulation technique in this work has the potential to meet the requirements of next-generation 3D architecture.

A dielectric material with a higher permittivity and a lower leakage is required to meet the demands of three-dimensional (3D) dynamic random access memory (DRAM). Current morphotropic phase boundary (MPB) behavior exhibits a higher permittivity but relatively high leakage. In this work, we propose a feasible approach to achieve MPB and low leakage by the charge balance effect in the doped HfO2-ZrO2 superlattice system. Our first-principles calculations reveal that the synergy effect of doping and oxygen vacancies can achieve lower phase transition barriers between polar and nonpolar phases, suggesting the formation of more MPB regions. Especially for Y dopant, it is more preferred due to the smallest transition barrier. Additionally, defect states arising from oxygen vacancies can be passivized at the charge balance state to enable large bandgap, suppressing leakage currents. This work provides a potential solution for a dielectric material with a higher permittivity and a lower leakage, paving the way for future 3D DRAM capacitors.

In the realm of advanced integrated circuits, the demand for novel resist materials becomes paramount as we progress toward smaller process nodes. Inorganic photoresists have received widespread attention due to their higher absorption of extreme ultraviolet (EUV) light and higher etch resistance. In our study, we employed trimethylaluminum (TMA) and 2-butene-1,4-diol (BED) via molecular layer deposition (MLD) to deposit an Al-based hybrid film coined “TMA–BED,” serving as an electron-beam photoresist. Through inductively coupled plasma (ICP) etching for resistance testing, the TMA–BED film exhibited exceptional selectivity with Si etching, reaching a minimum of ∼86, surpassing traditional photoresists by 14 times. Sensitivity and resolution were assessed using electron-beam lithography with 10 wt% ammonia as the developer, revealing a sensitivity of 450 μC cm⁻² at 2 keV and the capacity to resolve 10 nm line widths at 50 keV. Our results underscore the tremendous potential of TMA–BED hybrid films, deposited through MLD, for advanced lithographic techniques.