Hydrogen-containing plasmas are widely employed during advanced interconnect fabrication for post-etch cleaning and pre-barrier surface preparation. While the interaction of hydrogen plasma with porous organosilicate dielectrics has been extensively studied, the influence of framework architecture on plasma-induced degradation remains poorly understood. Understanding this relationship is essential for the rational design of next-generation porous low-k dielectrics, where framework architecture is increasingly used to tailor electrical and mechanical properties while maintaining plasma compatibility. In this work, the response of two representative porous low-k materials—methyl-terminated organosilicate glass (OSG) and ethylene-bridged periodic mesoporous organosilica (PMO)—to pure H2 capacitively coupled plasma was investigated using Fourier-transform infrared spectroscopy, spectroscopic ellipsometry, ellipsometric porosimetry, dielectric measurements, and DFT calculations.Hydrogen plasma exposure induces progressive removal of organic groups, transient formation of Si–H species, restructuring of the Si–O–Si network, film shrinkage, pore densification, and increased moisture uptake in both materials. DFT calculations show that VUV photons preferentially cleave Si–C bonds, whereas rupture of the Si–O–Si backbone is energetically much less favorable. The transient evolution of Si–H is consistent with a consecutive reaction model involving VUV-induced formation of silicon dangling bonds, hydrogen passivation, and subsequent reconstruction of the silica network.Despite these common transformation pathways, PMO exhibits significantly slower degradation kinetics, delayed Si–H formation, and greater resistance to structural collapse than OSG. These differences are attributed to the distinct framework architecture of PMO, where ethylene bridges incorporated into the network retard hydrogen-assisted structural modification. The increase in dielectric constant is shown to arise predominantly from moisture adsorption during post-plasma exposure to ambient air rather than from intrinsic changes in the silica network.These results demonstrate that framework architecture governs not only the kinetics of hydrogen-plasma-induced structural evolution but also the resulting moisture sensitivity and dielectric degradation of porous low-k dielectrics.
Thin conductive films deposited on the surface of the heat-sensitive element of the radiation receiver make it possible to absorb up to 50% of the incident radiation. This increases the efficacy of detectors in the terahertz (THz) frequency range. The absorbing conductive coating on the array of a multi-pixel detector is an ordered structure with dimensions comparable to the wavelength of THz radiation. Diffraction of radiation on this structure leads to a change in the wavefront of both transmitted and reflected waves, leading to image distortion in a multi-pixel detector. Based on experimental data obtained using pulsed THz and IR Fourier spectroscopy, the transmission and conductivity spectra of solid films and capacitive Al meshes of different thicknesses were analyzed. The optimal thickness of the Al coating for maximum absorption of THz radiation has been determined. The transmission spectra of capacitive grids with an Al film thickness corresponding to the maximum absorption indicate the disappearance of diffraction effects in the THz range.
The impact of the spatial arrangement of the terminal methyl group in relation to the bridging ethylene group on the properties of PMO films has been studied using pairs of BTMSE-MTMS and TESDEMSE-MTMS precursors containing C-C bridging groups. TESDEMSE features a Si-attached CH3 group within the same molecule, forming hydrophobic films independently of MTMS concentration. Pure BTMSE-based films are hydrophilic and exhibit an increased dielectric constant due to water adsorption. The addition of MTMS to BTMSE introduces CH3 into the films, rendering them hydrophobic. The spatial arrangement of CH3 relative to C-C significantly affects hydrophobicity, dielectric properties, thermal stability, and porosity. The mechanical properties of the films also depend on the location of CH3 groups. TESDEMSE demonstrates potential as a single precursor for low-k film deposition. However, annealing (curing) at 430 °C reduces the concentration of C-C bonds, and this phenomenon is more pronounced in TESDEMSE-based films. Quantum chemical analysis indicates that the ethylene bridge is generally weaker than the terminal methyl group, with the presence of an adjacent methyl group further decreasing its stability. The low thermal stability of these films poses a challenge for certain practical applications.
A novel approach for the preparation of ferroelectric composite films has been successfully developed by combining sol-gel evaporation-induced self-assembly (EISA) of porous lead zirconate titanate (PZT) films with atomic layer deposition (ALD) of titania. The EISA process, which utilizes a Brij-type surfactant, facilitates the formation of large columnar perovskite grains with narrow (similar to 20 nm) interconnected pores. ALD, employing the thermal reaction of titanium isopropoxide with water, ensures uniform titania growth within the pores throughout the film thickness, as demonstrated by transmission electron microscopy and ellipsometric porosimetry. The resulting PZT-TiOx composite films exhibit a pronounced photovoltaic current under visible light illumination, attributed to electron excitation from the valence band to Ti3+ states, followed by movement via a hopping conduction mechanism. The photocurrent value varies with the direction of polarization. This behavior presents a potential method for controlling photoconductivity through polarization, with possible applications in electronic and photonic devices.
Organosilica films, composed of a silicon oxide network with terminal methyl groups, are widely utilized in various applications, including microelectronics. Many of these applications require high hydrophobicity and good mechanical properties, which pose a significant challenge because the Si-CH3 groups disrupt the Si-O-Si network. This issue becomes particularly pronounced in porous films. Here, we investigate whether material properties can be tuned by simply altering the spatial arrangement of methyl groups. To achieve this, we prepared copolymer films with one or two methyl groups bonded to a silicon atom, while maintaining a constant total amount of methyl groups. The films were deposited using a sol-gel technique combined with template self-assembly. The precursor content was varied to compare films with different proportions of Si-CH3 and Si(-CH3)2. Film characterization included FTIR, ellipsometric porosimetry, AFM, and WCA measurements and dielectric constant evaluations. Our findings indicate that precursors containing dimethyl groups enhance the connectivity of the Si-O-Si network, resulting in a higher Young's modulus and smaller pore size compared to films with an equivalent amount of methyl groups. However, the lower thermal stability of dimethyl bonds limits the thermal budget of these films. Thus, the spatial arrangement of organic groups within the polymer structure can be employed to tune material properties. These results expand the understanding of organic-inorganic hybrid materials and offer novel approaches for their applications.
This work reviews percolation-related phenomena in porous organosilica glass (OSG) low-k dielectrics and their critical impact on mass transport, electrical conductivity, mechanical integrity, and dielectric breakdown. We discuss how leakage current arises from the formation of minimal percolating conductive paths along pores and defect chains, while dielectric breakdown requires system-spanning pore connectivity, resulting in a higher effective percolation threshold. Mechanical properties similarly degrade when pores coalesce into a connected network, exhibiting multiple percolation thresholds due to both chemical network modifications and porosity. Experimental trends demonstrate that leakage current increases sharply at low porosity, whereas breakdown voltage and mechanical stiffness collapse at higher porosity levels (~20%–30%). We highlight that distinct percolation classes govern transport, mechanical, and nonlinear phenomena, with correlation length and diffusion timescales providing a unified framework for understanding these effects. The analysis underscores the fundamental role of network connectivity in determining the performance of organosilicate glass-based ultra-low-k dielectrics and offers guidance for material design strategies aimed at simultaneously improving electrical, mechanical, and chemical robustness.
Organosilica films with a silicon oxide network and terminal methyl groups are widely used for various applications, including microelectronics. Most of them require high hydrophobicity and good mechanical properties, which is a challenge because Si–CH3 blocks some directions of the metal–oxide network. Here, we discuss an alternate way to prepare organosilica films in which the methyl group is changed to dimethyl. The films were deposited by the sol–gel technique using a non-ionic surfactant to provide porosity. The precursor content was varied to compare the films with different contents of Si–CH3 and Si(–CH3)2. The characterization of the films includes FTIR, ellipsometric porosimetry, PFQNM AFM, wetting contact angle, and dielectric constant. We found that the use of precursors containing dimethyl groups leads to an increase in Si–O–Si network connectivity and hence a higher Young's modulus value compared to films containing the same amount of methyl groups. However, the lower thermal stability of the dimethyl bonds leads to some deterioration of hydrophobic behavior and related properties. These new results extend the knowledge of organic-inorganic hybrid materials and provide new approaches for their applications.
The effect of vacuum ultraviolet (VUV) radiation during ionized physical vapor deposition (IPVD) of tantalum barriers on various porous organosilicate glass low-k SiCOH films is studied using advanced diagnostics and quantum chemical calculations. VUV photons break the Si-C bonds, releasing hydrocarbon radicals from the pore surfaces. These radicals, trapped in pores that are partially sealed by tantalum deposition, can either react with tantalum to form carbide-like compounds, TaCx, or be redeposited in the pores as CHx polymers. This is evidenced by a decrease in CH3 groups that correlates with an increase in TaCx. The formation of TaCx poses a significant challenge in the back end of line (BEOL) technology when reducing the barrier thickness.
The influence of annealing temperature on the chemical, structural, and electrophysical properties of porous OSG low-k films containing terminal methyl groups was investigated. The films were deposited via spin coating, followed by drying at 200 °C and annealing at temperatures ranging from 350 °C to 900 °C. In the temperature range of 350–450 °C, thermal degradation of surfactants occurs along with the formation of a silicon-oxygen framework, which is accompanied by an increase in pore radius from 1.2 nm to 1.5 nm. At 600–700 °C, complete destruction of methyl groups occurs, leading to the development of micropores. FTIR spectroscopy reveals that after annealing at 700 °C, the concentration of silanol groups and water reaches its maximum. By 900 °C, open porosity is no longer observed, and the film resembles dense SiO2. JV measurements show that the film annealed at 450 °C exhibits minimal leakage currents, approximately 5 × 10−11 A/cm2 at 700 kV/cm. This can be attributed to the near-complete removal of surfactant residues and non-condensed silanols, along with non-critical thermal degradation of methyl groups. Leakage current models obtained at various annealing temperatures suggest that the predominant charge carrier transfer mechanism is Poole–Frenkel emission.
In this work, the effects of solvent type and surfactant (porogen) on the properties of porous methyl-modified spin-on films were investigated. A qualitative assessment of the defectivity of the formed films was carried out. The refractive index, dielectric permittivity, and porosimetric properties of the films were analyzed using the method of spectral ellipsometry, frequency dependence of capacitance analysis, and porosimetry. It was found that the film properties depend more strongly on the surfactant type than on the solvent type. The highest porosity value is obtained with the use of nonionic surfactant Brij® 76, which has a higher molecular weight. At the same time, at lower molecular weight, the ionic surfactant CTAB provides comparable porosity. Despite the high porosity, samples from film-forming solutions containing CTAB do not exhibit a lower dielectric constant, which is presumably due to their hydrophilicity or porogen residue. The lowest value of the dielectric constant k ≈ 2.1 is typical for films made from film-forming solutions containing Brij® 76. The application of other porogens allows us to obtain a k value 2.3–2.4.
Thin porous sol-gel organosilicate glass (OSG) films containing methylene (Me-OSG), ethylene (Et-OSG), or phenylene (Ph-OSG) bridges between Si atoms, along with terminal methyl groups, were spin-coated onto Si wafers. Porosity was generated using the Brij (R) L4 template. The investigation focused on examining the effects of annealing (200-1000 degrees C, 30 min) on the properties of the micro/mesoporous films. The changes in the properties of the films during the annealing process at different temperatures are impacted by the evaporation of solvents, condensation reactions, and destruction of the porogen (200-400 degrees C). Additionally, the degradation of terminal and bridging organic groups has been observed to occur within the temperature range of 200-600 degrees C. Finally, the films undergo densification through subsequent condensation and viscous sintering within a temperature range of 700-1000 degrees C. Ph-OSG films demonstrate remarkable resistance to temperatures of similar to 400 degrees C. Additionally, these films exhibit the highest Young's Modulus (YM) and the smallest pore radius (YM approximate to 6.7 GPa and R approximate to 1 nm after 400 degrees C annealing). It is important to acknowledge that these materials exhibit a relatively hydrophilic nature, significant shrinkage, and higher refractive index (RI) and dielectric constant (k) compared to the MeOSG and Et-OSG films. Me-OSG films demonstrate the highest hydrophobicity and porosity, along with minimal shrinkage, RI, and k. However, they also possess the largest pore radius (R = 1.7-2.2 nm after undergoing annealing at 400-550 degrees C). Modeling the concentrations of different species reveals that the predicted changes in concentrations are strongly dependent on the number of hydroxyl groups present on the surface of the pore walls. The decrease in the number and/or polarizability of OH groups leads to an increased impact of other species on the dielectric constant, resulting in higher computed values.
Organosilicate glass (OSG) films are a critical component in modern electronic devices, with their electrical properties playing a crucial role in device performance. This comprehensive review systematically examines the influence of chemical composition, vacuum ultraviolet (VUV) irradiation, and plasma treatment on the electrical properties of these films. Through an extensive survey of literature and experimental findings, we elucidate the intricate interplay between these factors and the resulting alterations in electrical conductivity, dielectric constant, and breakdown strength of OSG films. Key focus areas include the impact of diverse organic moieties incorporated into the silica matrix, the effects of VUV irradiation on film properties, and the modifications induced by various plasma treatment techniques. Furthermore, the underlying mechanisms governing these phenomena are discussed, shedding light on the complex molecular interactions and structural rearrangements occurring within OSG films under different environmental conditions. It is shown that phonon-assisted electron tunneling between adjacent neutral traps provides a more accurate description of charge transport in OSG low-k materials compared to the previously reported Fowler–Nordheim mechanism. Additionally, the quality of low-k materials significantly influences the behavior of leakage currents. Materials retaining residual porogens or adsorbed water on pore walls show electrical conductivity directly correlated with pore surface area and porosity. Conversely, porogen-free materials, developed by Urbanowicz, exhibit leakage currents that are independent of porosity. This underscores the critical importance of considering internal defects such as oxygen-deficient centers (ODC) or similar entities in understanding the electrical properties of these materials.
UV-induced photoluminescence of organosilica films with ethylene and benzene bridging groups in their matrix and terminal methyl groups on the pore wall surface was studied to reveal optically active defects and understand their origin and nature. The careful selection of the film's precursors and conditions of deposition and curing and analysis of chemical and structural properties led to the conclusion that luminescence sources are not associated with the presence of oxygen-deficient centers, as in the case of pure SiO2. It is shown that the sources of luminescence are the carbon-containing components that are part of the low-k-matrix, as well as the carbon residues formed upon removal of the template and UV-induced destruction of organosilica samples. A good correlation between the energy of the photoluminescence peaks and the chemical composition is observed. This correlation is confirmed by the results obtained by the Density Functional theory. The photoluminescence intensity increases with porosity and internal surface area. The spectra become more complicated after annealing at 400 °C, although Fourier transform infrared spectroscopy does not show these changes. The appearance of additional bands is associated with the compaction of the low-k matrix and the segregation of template residues on the surface of the pore wall.
The degradation of a porous organosilicate glass low-k dielectric during the ionized physical vapor deposition of tantalum coating is studied. The main contribution to the damage is made by vacuum UV flux (10(14)-10(15) s(-1) cm(-2)) from the argon inductively coupled plasma of the ionizer, and the effect of the direct current magnetron sputter plasma is small. The damage by vacuum ultraviolet photons with an energy exceeding the band gap of the SiO2 matrix is associated not only with the removal of carbon-containing groups (terminal CH3 and bridging CH2) but also with the breaking of Si-O bonds in the Si-O-Si matrix followed by the formation of hydrophilic Si-OH and Si-H groups. Consequently, the degree of damage can be much higher than would be expected from the depth of CH3 group depletion.
The subtractive process of forming a metallization system for integrated circuits has been studied. Structures with aluminum and copper conductors with different pitches were used as models. The gaps between the conductors were filled using the chemical solution deposition technique. The formed organosilicate layers provided complete or partial planarization of the relief. Electrical measurements indicated a decrease in capacitance and leakage currents in structures with nanoporous dielectric layers.
UV induced photoluminescence of organosilica films with ethylene and benzene bridging groups in their matrix and terminal methyl groups on the pore wall surface is studied to reveal optically active defects and understand their origin and nature. Careful selection of the film’s precursors and conditions of deposition and curing, analysis of chemical and structural properties led to the conclusion that luminescence sources are not associated with the presence of oxygen-deficient centers, as in the case in pure SiO2. It is shown that the sources of luminescence are the carbon-containing components that are part of the low-k-matrix, as well as the carbon residues formed upon removal of the template and UV induced destruction of organosilica samples. A good correlation between the energy of the photoluminescence peaks and the chemical composition is observed. This correlation is confirmed by the results obtained by the Density Functional theory. The photoluminescence intensity increases with porosity and internal surface area. The spectra become more complicated after annealing at 400 °C, although Fourier transform infrared spectroscopy does not show these changes. The appearance of additional bands is associated with compaction of low-k matrix and segregation of template residues on the surface of the pore wall.
Conductive LaNiO3 (LNO) films with an ABO3 perovskite structure deposited on silicon wafers are a promising material for various electronics applications. The creation of a well-defined columnar grain structure in CSD (Chemical Solution Deposition) LNO films is challenging to achieve on an amorphous substrate. Here, we report the formation of columnar grain structure in LNO films deposited on the Si-SiO2 substrate via layer-by-layer deposition with the control of soft-baking temperature and high temperature annealing time of each deposited layer. The columnar structure is controlled not by typical heterogeneous nucleation on the film/substrate interface, but by the crystallites' coalescence during the successive layers' deposition and annealing. The columnar structure of LNO film provides the low resistivity value ρ~700 µOhm·cm and is well suited to lead zirconate-titanate (PZT) film growth with perfect crystalline structure and ferroelectric performance. These results extend the understanding of columnar grain growth via CSD techniques and may enable the development of new materials and devices for distinct applications.
Porous ferroelectric lead zirconate titanate (PZT) films are a promising material for various electronic applications. This study focuses on understanding how the structure-directing agent, polyvinylpyrrolidone, can alter the structure and electrical properties of porous PZT films prepared through chemical solution deposition. Films with various porosities of up to ~40 vol.% and pore connectivities from 3-0 to 3-3 were prepared and studied by capacitance–voltage, dielectric hysteresis, transient current, photocurrent, and local current techniques. We have found that a linear decrease in material volume in a porous film is not the only factor that determines film properties. The creation of new internal grain boundaries plays a key role in changing electrical properties. This research expands the understanding of physical phenomena in porous ferroelectric films and may facilitate the development of new materials and devices.
Исследован субтрактивный процесс создания системы металлизации интегральных схем. В качестве модельных использованы структуры с алюминиевыми и медными проводниками, имеющие различный шаг. Заполнение зазоров между проводниками проводилось методом химического осаждения из раствора. Сформированные органосиликатные слои обеспечивали полную или частичную планаризацию рельефа. Электрические измерения свидетельствовали о снижении ёмкости и токов утечек в структурах с нанопористыми диэлектрическими слоями.
This article studies various methods for the formation of dielectric diffusion barriers between open areas of copper and an organosilicate low- k dielectric in the subtractive method of forming a metallization system, in which metal lines are first formed, and then a low- k dielectric is deposited. Films of dense and porous organosilicate glass deposited by chemical deposition from solutions are used as a low- k dielectric. A comparison is made between AlN barrier layers formed by atomic layer deposition and SiCN barriers deposited by plasma-assisted chemical vapor deposition. The successful formation of a model structure of copper metallization using AlN barriers is demonstrated.