Effects of methyl terminal and carbon bridging groups ratio on critical properties of porous organosilicate-glass films

Organosilicate glass-based porous low dielectic constant films with different ratios of terminal methyl to bridging organic (methylene, ethylene and 1,4-phenylene) groups are spin-on deposited by using a mixture of alkylenesiloxane with organic bridges and methyltrimethoxysilane, followed by soft baking at 120–200◦ C and curing at 430◦ C. The films’ porosity was controlled by using sacrificial template Brij® L4. Changes of the films’ refractive indices, mechanical properties, k-values, porosity and pore structure versus chemical composition of the film’s matrix are evaluated and compared with methyl-terminated low-k materials. The chemical resistance of the films to annealing in oxygen-containing atmosphere is evaluated by using density functional theory (DFT). It is found that the introduction of bridging groups changes their porosity and pore structure, increases Young’s modulus, but the improvement of mechanical properties happens simultaneously with the increase in the refractive index and k-value. The 1,4-phenylene bridging groups have the strongest impact on the films’ properties. Mechanisms of oxidative degradation of carbon bridges are studied and it is shown that 1,4-phenylene-bridged films have the highest stability. Methylene-and ethylene-bridged films are less stable but methylene-bridged films show slightly higher stability than ethylene-bridged films. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Uterine leiomyosarcoma and disseminated peritoneal leiomyomatosis in the surgical treatment of uterine myoma: a retrospective analysis

Aim. To analyze the incidence and types of adverse outcomes and complications of laparoscopic myomectomies. Materials and methods. This work is a retrospective study based on data from the Kulakov National Medical Research Center for Obstetrics, Gynecology, and Perinatology. We analyzed 711 case histories of patients diagnosed with uterine myoma who received surgical treatment in the Department of Innovative Oncology and Gynecology from 2015 to 2019. The frequency of malignant neoplasms, verified by pathomorphological examination, and the characteristics of surgical interventions performed in these patients were comparatively evaluated. Results. Surgical interventions for uterine myoma are leading in gynecology due to the high prevalence of such disorders. Conservative myomectomy remains the "gold standard" in organ-sparing surgery. However, during surgeries for suspected benign neoplasms, there is a risk of morcellation of the malignant tumor, significantly worsening patient survival outcomes. In our study, the incidence of uterine leiomyosarcoma in suspected benign neoplasms was 0.98%. The probability of parasitic myomas or disseminated perineal leiomyomatosis after myomatous nodule morcellation is 0.19%. Conclusion. No reliable information about the malignant potential of the tumor and its proliferative activity can be obtained until a definitive pathomorphological examination. The above considerations warrant the routine use of prophylactic measures to prevent tumor cell dissemination

Control of Columnar Grain Microstructure in CSD LaNiO₃ Films

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

Data publication: Modification of Porous Ultralow‑k Film by Vacuum Ultraviolet Emission

Modification of spin-on-deposited porous PMO (periodic mesoporous organosilica) ultralow-k (ULK) SiCOH films (k = 2.33) containing both methyl terminal and methylene bridging groups by vacuum ultraviolet (VUV) emission from Xe plasma is studied. The temporal evolution of chemical composition, internal defects, and morphological properties (pore structure transformation) is studied by using Fourier transform infrared spectroscopy, in situ laser ellipsometry, spectroscopic ellipsometry, ellipsometric porosimetry (EP), positron-annihilation lifetime spectroscopy (PALS), and Doppler broadening positron-annihilation spectroscopy. Application of the different advanced diagnostics allows making conclusions on the dynamics of the chemical composition and pore structure. The time frame of the VUV exposure in the current investigation can be divided into two phases. During the first short phase, film loses almost all of its surface methyl and matrix bridging groups. An increase of material porosity due to removal of methyl groups with simultaneous matrix shrinkage is found by in situ ellipsometry. The removal of bridging bonds leads to an increase of matrix intrinsic porosity. Nevertheless, when the treated material is exposed to the ambient air, the sizes of micro- and mesopores and pores interconnectivity decrease with the VUV exposure time according to PAS and EP data. The last is the result of the additional film shrinkage caused by atmosphere exposure. During the second phase the increase of mesopore size is detected by both EP and PAS. The increase of mesopore size goes all the time as it is expected from in situ ellipsometry, but it is masked by the air exposure