Role of Slurry Additives on Chemical Mechanical Planarization of Silicon Dioxide Film in Colloidal Silica Based Slurry

Chemical mechanical planarization (CMP) is a critical process for smoothing and polishing the surfaces of various material layers in semiconductor device fabrication. The applications of silicon dioxide films are shallow trench isolation, an inter-layer dielectric, and emerging technologies such as CMOS Image Sensor. In this study, the effect of various chemical additives on the removal rate of silicon dioxide film using colloidal silica abrasive during CMP was investigated. The polishing results show that the removal rate of silicon dioxide film first increased and then decreased with an increasing concentration of K+, pH, and abrasive size. The removal rate of silicon dioxide film increased linearly as the abrasive concentration increased. The influence mechanisms of various additives on the removal rate of silicon dioxide film were investigated by constructing simple models and scanning electron microscopy. Further, the stable performance of the slurry was achieved due to the COO- chains generated by poly(acrylamide) hydrolysis weaken the attraction between abrasives. High-quality wafer surfaces with low surface roughness were also thus achieved. The desirable and simple ingredient slurry investigated in this study can effectively enhance the planarization performance, for example, material removal rates and wafer surface roughness.

Capacitive Measurements of SiO2 Films of Different Thicknesses Using a MOSFET-Based SPM Probe

We utilized scanning probe microscopy (SPM) based on a metal-oxide-silicon field-effect transistor (MOSFET) to image interdigitated electrodes covered with oxide films that were several hundred nanometers in thickness. The signal varied depending on the thickness of the silicon dioxide film covering the electrodes. We deposited a 400- or 500-nm-thick silicon dioxide film on each sample electrode. Thick oxide films are difficult to analyze using conventional probes because of their low capacitance. In addition, we evaluated linearity and performed frequency response measurements; the measured frequency response reflected the electrical characteristics of the system, including the MOSFET, conductive tip, and local sample area. Our technique facilitated analysis of the passivation layers of integrated circuits, especially those of the back-end-of-line (BEOL) process, and can be used for subsurface imaging of various dielectric layers.

Surface Analysis of Amorphous Carbon Thin Film for Etch Hard Mask

When the aspect ratio of a high aspect ratio (HAR) etching process is greatly increased, an amorphous carbon layer (ACL) hard mask is required for dynamic random-access memory (DRAM). To improve the durability of an etch hard mask, an understanding of the plasma deposition mechanisms and the deposited film properties associated with the plasma conditions and atomic structure, respectively, is required. We performed a series of plasma depositions, material characterizations and dry-etching to investigate the effect of the deposition process condition on the surface characteristics of an ACL film to be used as a dry etch hard mask in an HAR etch process. We found that a lower chamber pressure at a higher temperature for the plasma deposition process yielded higher film hardness, and this infers that higher plasma ion energy in lower pressure regions helps to remove hydrogen atoms from the surface by increased ion bombardment. It was postulated that a higher substrate temperature gears the bake-out of hydrogen or hydroxide contaminants. From the results of inductively coupled plasma-reactive ion etching of the deposited ACL film, we observed that the etch selectivity over the silicon dioxide film was improved as C═C sp2 and C–C sp3 bonds increased.

СОСТАВ, СТРУКТУРА И ЭЛЕКТРОХИМИЧЕСКАЯ АКТИВНОСТЬ СИЛИЦИДА ТИТАНА В РЕАКЦИИ ВЫДЕЛЕНИЯ ВОДОРОДА

The phase composition and structure of titanium silicide have been investigated by X-ray diffraction and X-ray spectral microanalysis methods. It has been found that the investigated silicide is a singlephase system consisting of a high-temperature TiSi2 modification with a rhombic face-centered lattice. The cathodic behavior of the TiSi2 electrode has been studied by the methods of polarization and capacitance measurements. It has been found that the cathodic potentiostatic curves of silicide in solutions of 0,5 M H2SO4; 0,5 M H2SO4 + 0,005 M NaF and1,0 M NaOHhave Tafel sections with slopes of 0,120; 0,097 and 0,109 V and they are characterized by the values of the hydrogen evolution overvoltage 0,90; 0,64 and 0,74 V (at i = 1 A/cm2), respectively. Titanium disilicide in sulfuric acid solution belongs to materials with a high overvoltage of hydrogen evolution, but in a fluoride-containing sulfuric acid solution and in an alkaline solution - to materials with a low overvoltage of hydrogen evolution. Based on measurements of the differential capacitance of the TiSi2 electrode (at f = 10 kHz), it has been concluded that a thin silicon dioxide film (Si + 2H2O → SiO2 + 4H+ + 4e–)is present on the surface of the silicide in the acidic fluoride-free electrolyte.

Влияние кислородных вакансий на формирование и структуру филамента в мемристорах на основе диоксида кремния

The improvement of the parameters of the SiO2-based memristor is found when creating displacement cascades in the near-surface layer of a silicon dioxide film by irradiation with Xe+ ions. Molecular dynamic modeling of the structure of amorphous SiO2 enriched with oxygen vacancies has shown the possibility of nucleation of silicon nanoclusters, which can play a significant role in the formation and evolution of current conducting paths (filaments) and thereby affect the parameters of the memristor.