OPC Solution Research Articles

Understanding the intrinsic effect of fly ash on passivity and chloride-induced corrosion of carbon steel and stainless steel in cement extract solutions

Compared with the ordinary Portland cement extract solution (OPC solution), the passivation capability and chloride-induced corrosion behavior of carbon steel (Q235) and 316 stainless steel (316ss) in fly ash modified cement extract solution (FA solution) were intensively investigated in this study. The composition and electrochemical properties of steel passive films were studied using XPS technique and a series of electrochemical measurements including M − S, EIS and CPP. Moreover, FT-IR, AFM and SEM/EDS were employed to analyze the corrosion products and morphology on the steel surface. After 10 d of passivation, the film resistance of Q235 in OPC solution was 1.42 times that in FA solution, but an opposite result was observed for 316ss, which is consistent with the subsequent chloride-induced corrosion behavior. Steel passive films of different thicknesses and protective characteristics for Q235 and 316ss formed in alkaline solutions were confirmed to be the dominating reason for the distinct passivity and corrosion resistance to chloride attack. Accordingly, the intrinsic impact mechanisms of fly ash on passivation capability and chloride-induced corrosion of Q235 and 316ss in extract solutions were proposed.

A Review of Advances in Peat Soil Stabilisation Technology: Exploring the Potential of Palm Oil Fuel Ash Geopolymer as a Soil Stabiliser Material

This study aims to highlight the latest developments in the field of peat soil stabilisation technology via chemical stabilisation. The review examines the use of traditional stabilisers such as OPC and various non-traditional stabiliser materials, i.e., Palm Oil Fuel Ash (POFA)-OPC blends, chemical solutions, and geopolymer materials, to enhance the Unconfined Compressive Strength (UCS) characteristics of peat soils based on the ASTM D 4609 requirements. OPC, POFA-OPC blends, and alkaline solutions mostly produced stabilised soil samples that fell short of the ASTM requirements. Existing studies on the use of waste-derived geopolymers to treat peat soils are limited, while the use of POFA geopolymer materials has mostly focused on the improvement of clayey and silty soils. The results of soil stabilisation with geopolymer were very encouraging, as the strength gains were in line with the ASTM soil strength requirements. As a result of this review, it can be concluded that POFA geopolymer is a viable soil stabiliser material with the addition of Ground Granulated Blast Furnace Slag, and that the use of POFA-GGBFS geopolymer to enhance the strength properties of peat soils should be investigated. Doi: 10.28991/CEJ-2023-09-08-017 Full Text: PDF

Can optical proximity correction solution be learned? The learning limit and a general learning framework

BackgroundOptical proximity correction (OPC) is an indispensable technology that has been propelling the advancement of computational lithography technology. To tightly control edge placement error (EPE) and maintain lithography process window, the demands on OPC computational resources and OPC turnaround time are growing rapidly with alarming acceleration. To tame the trend, machine learning technologies have been explored; however, an in-depth discussion on OPC solution learning limit is still lacking.AimWe aim to present an in-depth discussion on OPC solution learning limit and propose a general machine learning OPC framework that can be extended to curvilinear mask OPC technology.ApproachIn this study, we first investigate the machine learning OPC learning limit by examining noninverse lithography technology (non-ILT) OPC solution space characteristics inherited from edge segmentation and control point setting rules and then propose a general machine learning OPC framework that can take full advantage of deep convolution neural network (DCNN) learning capability while being able to preserve mask data high resolution.ResultsWith this machine learning OPC framework, we have achieved models with average absolute model error <1 nm for 14-nm metal layer. With single GPU, the average time for machine learning OPC models to produce results of 3840 nm × 3840 nm area is 8.74 ms for single channel input model and 12.65 ms for six channels input model.ConclusionsFor non-ILT OPC solution, there is an intrinsic learning limit inherited from edge segmentation rules. Machine learning OPC models should be content with learning low order OPC solutions. This intrinsic learning limit of non-ILT OPC solution may diminish for ILT OPC solution when the constraint on degrees of freedom of OPC solution is lifted. The machine learning OPC framework we proposed is general and extendable to curvilinear OPC technology.

Comparison of different activators for alkaline activation of construction and demolition wastes

Currently, construction and demolition waste (CDW) is the most generated waste worldwide. In Colombia, ~ 22 million tons of CDW are generated per year, of which 1.0 million tons are generated in Santiago de Cali; therefore, the mitigation and reuse of CDW are important for reducing the environmental impact of the construction sector. This article presents a study on the application of CDW alkaline activation technology for the manufacture of pastes and mortars using alkaline activators with lower environmental impact, such as sodium sulfate and sodium hydroxide. Geopolymeric pastes were produced using a mixture of 80%CDW-20%OPC and activator solutions with concentrations of Na2O between 0.44% and 1.31%. The pastes were manufactured with fine aggregate obtained from the same CDW. The materials developed were characterized microstructurally, physically and mechanically. The scanning electron microscopy (SEM-EDX) and XRD results, the reaction products were C-(A)-S-H, C-S-H gels and minority (N),C-(A)-S-H gel. Additionally, in the sodium-sulfate-activated pastes, ettringite was identified as an additional hydration product through SEM and X-ray diffraction (XRD). Binders activated with sodium sulfate 0.8% Na2O (solid-state activator) yielded compressive strengths up to 18 MPa for pastes. These results provide an opportunity for the potential reuse of CDW in new eco-friendly binders.

Optimization of M1 to Contact Connection in Sub-40nm Node

This paper presents integration challenges associated with M1 to CT connection in Ultra low-k (ULK) Back-End-Of-Line (BEOL) interconnects for 40nm node and beyond. In advance IC fabrication, porous dielectric materials, such as BDII (related dielectric constant k about 2.5), are commonly used as insulator in copper interconnects for RC delay reduction. But the material of inter-dielectric layer is still high density SiO2-based. Hence, the difference in materials of PMD and IMD would potentially induce mismatch of physical properties of the two types of dielectric and cause deterioration of M1 to Contact connection, which would further impact product yield by contact open or other issues. Cross section pictures of failing M1 to CT connection were exhibited with a special spacer profile and investigated to illustrate the phenomenon. Solutions were proposed, through optimization of Etch, Wet clean and CMP to improve process window. Layout optimization is also suggested as OPC and DFM solution for related layers. Some of the solutions were examined by experiments with 40nm BEOL test masks. Results of physical and electric characterization were presented and discussed.

Lithography Process Transfer from ArF to High-NA KrF Tool

In this paper, we present the capabilities of lithographic process transfer by use of high NA KrF tool (TWINSCAN XT:1000H, Maximal NA 0.93). The Metal 1 (100 nm half-pitch)and Via (110 nm half-pitch) layers of 65 nm technology have been chosen for this research. The layers belong to customer product that is currently manufactured on ArF tool (TWINSCAN XT:1400). By optimizing illumination setting and applying advanced OPC solution, we have obtained the overlapping process window of critical features for the KrF process that is comparable with parameters of the initial ArF process. A good performance of Metal layer with respect to MEEF (Mask Error Enhancement Factor) also allows for stable process characteristics within wide line through pitch range. However, to ensure CD uniformity for Via layer an aggressive illumination solution such as soft-QUASAR or customized illumination may be required.

Modeling of pH Elevation Due to the Reaction of Saline Groundwater with Hydrated Ordinary Portland Cement Phases

AbstractThermodynamic calculations of the reaction between hydrated OPC phases and saline groundwater indicate an elevated pH &gt; 13, which is not associated with the well known initial release of the alkalis. Instead, the pH elevation is attributed to the generation of OH− accompanied with the precipitation of Friedel's salt (Ca3Al2O6·CaCl2·10H2O; AFm-Cl2) from the reaction of portlandite (Ca(OH)2;CH) and hydrogarnet (Ca3Al2O6·6H2O; C3AH6) with chloride ions from the saline groundwater. If such a reaction mechanism were to occur in the context of the geological disposal of radioactive wastes, the impact of a hyper alkaline plume on other barrier components, such as a bentonite buffer, could be significant. Experimental investigations were therefore conducted using only portlandite and hydrogarnet to represent hydrated OPC and NaCl solution to represent a saline groundwater. The pH elevation was confirmed and showed good agreement with the thermodynamic calculations. The experiments were repeated using hardened OPC paste to confirm this reaction mechanism in the presence of other hydrated OPC phases. In this case, however, the pH elevation was not as high as expected. This deviation can be explained by the residual aluminum, after being partially consumed by AFt and/or AFm, not being wholly assigned to hydrogarnet and a better agreement between the thermodynamic calculations and the experimentally measured results can be made assuming a fraction of aluminum is incorporated into the C-S-H gel phase.