Query: supercritical Co2 clean semiconductor narrow pattern

Candidate papers:

abstract: Supercritical fluids (SCFs) process can be considered as an emerging "clean" technology for the production of small size particles (e.g. micron size) Microsphere is a material in micron scale which has been widely used as adsorbent, catalyst support, and drug delivery system. For advanced application, those materials are formulated in the form of porous microspheres. There are several methods that can be used using SCFs. One of them is Solution Enhanced Dispersion by Supercritical Fluids (SEDS) This method is considered to be suitable in obtaining the porous microsphere polystyrene. In this study, polystyrene was first dissolved into toluene (polystyrene solution) at different concentrations (i.e. 3, 5, 7, 9, 11, 13, 15 wt% and then blown/sprayed together with supercritical carbon dioxide (CO2) through co axial nozzle with two differents annulus diameter (i.e. 3.6 mm and 4.6 mm) Co axial nozzle consists of two concentric pipes, inner pipe and annulus. Inner pipe for polystyrene solution flow and annulus for supercritical carbon dioxide flow. The expansion of these two of fluid was done both in atmospheric condition and in pressurized precipitator (40 bar) The resulted microsphere was analyzed by using SEM (Scanning Electron Microscope) to determine morphology and average diameter of the microsphere. The SEM analysis results showe that the smaller the initial concentration of solution used, the resulted microspheres tend to be smaller and less fibrils formed. Additionally, in the pressurized precipitator, the formed microspheres size was smaller and size distribution more narrow than that of atmospheric condition. Moreover, the use of smaller annulus diameter in co axial nozzle produced smaller microsphere size and the size distribution was more uniform.
author_names: Achmad Chafidz

Umi Rofiqah

Mujtahid Kaavessina

Thonthowy Jauhary
title: Production of Microsphere Polystyrene Using Solution Enhanced Dispersion by CO2 Supercritical Fluids (SEDS)
venue: Key Engineering Materials
year: 2019

abstract: Microcellular foams are well known polymeric materials since they present excellent properties: high impact strength, high toughness, high stiffness to weight ratio, high fatigue life as well as low dielectric constant and low thermal conductivity. Environment friendly techniques are being proposed to prepare polymeric foams. In particular, supercritical CO2 (scCO2) has received great attention instead of traditional blowing agents (chlorofluorocarbon hydrochlorofluorocarbons or hydrocarbons) due to its low cost and mild impact on the environment. In the foaming process proposed in this work, mild working conditions (90 bar and 30 degC) were required thanks to the presence of CO2 and p cymene, which benefits the nucleation and cell growth. The influence of inorganic particles (silica and montmorillonite) on the cell morphology was studied experimentally and theoretically in order to promote the simultaneous formation of the embryos, thereby reducing the average cell size and narrowing the cell size distribution. A great enhancement of the polystyrene foam homogeneity was observed, independent of the nucleating agent employed and under low temperature conditions.Graphical Abstract
author_names: Cristina Gutierrez

M Teresa Garcia

R Mencia

Ignacio Garrido

J F Rodriguez
title: Clean preparation of tailored microcellular foams of polystyrene using nucleating agents and supercritical CO2
venue: Journal of Materials Science
year: 2016

abstract: Facile synthesis and application of nano sized semiconductor metal oxides for optoelectronic devices have always affected fabrication challenges since it involves multi step synthesis processes. In this regard, semiconductor oxides derived directly from metal organic frameworks (MOFs) routes have gained a great deal of scientific interest owing to their high specific surface area, regular and tunable pore structures. Exploring the application potential of these MOF derived semiconductor oxides systems for clean energy conversion and storage devices is currently a hot topic of research. In this study, titanium based MIL 125(Ti) MOFs were used as a precursor to synthesize cobalt doped TiO2 based dye sensitized solar cells (DSSCs) for the first time. The thermal decomposition of the MOF precursor under an air atmosphere at 400 degC resulted in mesoporous anatase type TiO2 nanoparticles (NPs) of uniform morphology, large surface area with narrow pore distribution. The Co2+ doping in TiO2 leads to enhanced light absorption in the visible region. When used as photoanode in DSSCs, a good power conversion efficiency (PCE) of 6.86% with good photocurrent density (Jsc) of 13.96 mA cm 2 was obtained with the lowest recombination resistance and the longest electron lifetime, which is better than the performance of the pristine TiO2 based photoanode.
author_names: R Krishnapriya

C Nizamudeen

Bhagirath Saini

Mohammad Sayem Mozumder

Abdel Hamid I Mourad
title: MOF derived Co2+ doped TiO2 nanoparticles as photoanodes for dye sensitized solar cells
venue: Scientific reports
year: 2021

abstract: Introduction As semiconductor devices continue to shrink and become faster, new materials and processes will be required to enable the continuation of this progress. Supercritical CO2 (SCCO2) based technology has been proposed for various steps in device fabrication, such as cleaning and deposition. SCCO2 diffuses rapidly, has low viscosity, near zero surface tension like a gas, and thus, can penetrate easily into deep trenches and vias. It also enables cleaning without pattern collapse or stiction. SCCO2 has the solvating properties of a liquid and thus can dissolve chemicals, such as alcohols and fluorinated hydrocarbons, forming a homogenous supercritical fluid solution. SCCO2 based processing has been investigated because of its potential to strip photoresist residues (thanks to its compatibility with low k materials) [1] and because it can restore the k values of low k materials for Cu/low k integration in the back end of the line (BEOL) [2] The application of SCCO2 to ultra low k material processing is a promising future technique. In this paper, we first review various applications of SCCO2 in BEOL and then we demonstrate several applications of supercritical CO2 addressed to the front end of the line (FEOL) in semiconductor and nanoelectoronic device fabrication.
author_names: Koichiro Saga

Takeshi Hattori
title: Wafer Cleaning Using Supercritical CO2 in Semiconductor and Nanoelectronic Device Fabrication
year: 2007

abstract: Introduction The design rule of the recent memory device is rapidly shrinking. In particular, preventing the pattern collapse in drying process is the most critical task for controlling defects because high aspect ratio nano scale structures can be large enough to cause pattern collapse. The drying technology using supercritical CO2 fluid has been investigated in order to apply it to a semiconductor manufacturing process for years because of its excellent properties such as zero surface tension, inert gas and easy to handle it [1, 2, 3] However, there are many technical problems to apply supercritical CO2 drying process with controlling nanoscale defects to a 300mm wafer manufacturing. In our study, a large number of particles were detected on a 300mm wafer by supercritical CO2 drying processing. The process control of particles and defects on nano scale is necessary to achieve high yield of the memory device manufacturing. The authors aimed at supercritical CO2 drying process enabling particle control of less than 40nm size in order to apply it to 300mm wafer memory manufacturing.
author_names: Hidekazu Hayashi

Hisashi Ookuchi

Hiroshi Tomita

Yoshinori Ono

Tadashi Nakamori

Hiroshi Sugawara
title: Control Contaminations of Supercritical CO2 Drying Process for Nano scale Memory Manufacturing
year: 2013

abstract: Abstract We present a "one pot" supercritical approach for creating organized metal nanoparticle arrays. For this an improved method of deposition of micelles formed by semifluorinated poly(methyl methacrylate) block poly(perfluoroalkyl methacrylate) diblock copolymers in supercritical CO2 solution is applied. The presented approach provides metal clusters with a controlled inter particle spacing and relatively narrow size distributions in a single step "one pot" process during which the micelle formation proceeds simultaneously with organometallic Pt precursor dissolution and reduction inside the high pressure vessel containing a proper substrate. Subsequent decompression of the vessel results in patterned clusters of reduced metallic nanoparticles on the substrate. Presented approach of producing such raspberry like Pt clusters is relatively simple as compared to other time consuming multi step processes, and the resulting structures seem to be promising for electro catalytical applications.
author_names: Dmitry O Kolomytkin

Igor V Elmanovich

Sergey S Abramchuk

Larisa A Tsarkova

Doris Pospiech

Martin Moller

Marat O Gallyamov

Alexei R Khokhlov
title: Raspberry like Pt clusters with controlled spacing produced by deposition of loaded block copolymer micelles from supercritical CO2
year: 2015

abstract: Chemists and industrialists are continuously attempting to develop greener and more environmentally benign chemical processes to extract essential oils and bioactive metabolites of high purity, finding various applications in cosmetics, detergents, nutraceuticals and pharmaceuticals. An increase preference for natural products over synthetic ones has made supercritical fluid technology a primary alternative for the generation of high value bioactive ingredients. This effective technique requires only moderate temperatures, eliminates clean up steps, and avoids the use of harmful organic solvents. In this context, our study was focused on the chemical analysis of Calamintha nepeta subsp. nepeta aromatic extracts obtained with supercritical Carbon Dioxide (CO2 The effect of different operating conditions on the capacity of the lipophilic solvent to extract the targeted volatile components was also studied. The process was carried out at fairly low constant temperature of 40 degC, and with varying the pressure from 90 to 300 bar. The chemical composition of the extracts was analyzed by gas chromatography mass spectroscopy (GC MS) The results showed that the composition pattern, the concentrations of individual components and the quality of the extractable analytes, are affected by pressure increase. The extraction yields varied from 0.73 to 1.21 (wt. at 90 bar and 300 bar, respectively.
author_names: Haifa Debbabi

Ridha El Mokni

Siwar Majdoub

A G Aliev

Saoussen Hammami
title: The Effect of Pressure on the Characteristics of Supercritical Carbon Dioxide Extracts from Calamintha nepeta subsp. nepeta.
venue: Biomedical chromatography BMC
year: 2020

abstract: Abstract Supercritical carbon dioxide (SCCO2) is an established precision cleaning technique with applications in many different industries. The gas like viscosity and the liquid like density of CO2 are the key characteristics that allow the process to be tuned to the application. In addition, the very low surface tension of SCCO2 ensures high wettability and makes it very attractive for precision cleaning applications. The cleaning process is operated at near ambient temperatures. Applications range from cleaning and drying of micro and nanostructures such as carbon nanotubes; terminal sterilization of microbial organisms and food pasteurization; cleaning of metal surfaces, glass, optical elements, silicon wafers, and polymers; cleaning of soiled banknotes and other secure documents; precision cleaning and drying of narrow tubes and parts with complex geometries and tight spaces; sterilization of medical equipment; pesticide mitigation in museum collections; and decontamination of hazardous materials.
author_names: Rajiv Kohli
title: Applications of Supercritical Carbon Dioxide for Removal of Surface Contaminants
year: 2019

abstract: Abstract Photoreduction of CO2 into valuable fuels is a clean and sustainable way to mitigate the energy crisis and environmental problems. Factors limiting the efficiency of CO2 photoreduction include narrow band light absorption, poor charge carrier separation and transport, and sluggish activation/reaction of CO2 on the surface of photocatalyst. In recent years, defect engineering of photocatalysts emerges as an effective method to improve their efficiency in the photocatalytic conversion of CO2 into useful fuels. This review is focused on discussing how structural defects can be used to modulate the electronic structure of the photocatalysts and activate the inert CO2 molecules. Special emphasis is placed on the important impact of defects on the charge carrier dynamics of the photocatalysts. Our discussions cover a variety of defective semiconductors, including metal oxides, metal sulfides, and two dimensional materials. In addition, the challenges and prospects of defect engineering in photoreduction of CO2 are also analyzed. This review aims to provide useful information about the fundamental principles of photoreduction of CO2 and guidance on the design and preparation of defective photocatalysts.
author_names: Yiqiang He

Qiong Lei

Chunguang Li

Shouhua Feng
title: Defect engineering of photocatalysts for solar driven conversion of CO2 into valuable fuels
year: 2021

abstract: The invention discloses a supercritical CO2 cleaning device for semiconductor refrigeration; wherein, the device comprises a supercritical cleaning chamber which is used for cleaning silicon wafers and consists of a high pressure reaction chamber 4 and a temperature control chamber 5; wherein, the high pressure reaction chamber 4, used for storing silicon wafers and providing CO2 gasification cleaning, is arranged above the temperature control chamber 5 the temperature control chamber 5 is connected with the high pressure reaction chamber 4 by an evaporator coil, thus realizing the refrigerating and heating of the high pressure reaction chamber 4; the supercritical CO2 cleaning device also comprises a separation decompression chamber 6; the separation decompression chamber 6 is connected with the high pressure reaction chamber 4 by pipelines, is used for separating alcohols from CO2 after decompression and circularly uses the CO2; the supercritical cleaning chamber is fixedly connected with the separation decompression chamber 6 by a bearing platform 2. The supercritical CO2 cleaning device solves the problem of cleaning semiconductor in micro electrons technic, reduces the damage on the substrate, and achieves the object of saving energy by circularly utilizing the CO2.
title: Supercritical CO2 cleaning device for semiconductor refrigeration
year: 2007