Clean Silicon Wafers Research Articles

Entegris will sell bulk electronic chemical unit to Fujifilm

The specialty chemical firm Entegris has agreed to sell its bulk high-purity acid and solvent business to Fujifilm for $700 million. Entegris says the transaction, which is scheduled to close before the end of the year, will let the firm focus on its core businesses and help pay down debt. The unit moving to Fujifilm, called Electronic Chemicals, came in Entegris’s 2021 purchase of CMC Materials for $6.5 billion. CMC had bought the unit as part of a $1.6 billion acquisition of KMG Chemicals in 2018. The business, which had sales of about $360 million last year, supplies chemicals used to clean, etch, and dry silicon wafers during the chip fabrication process. Entegris bought CMC primarily to expand in chemical-mechanical planarization , a form of precision polishing that is done several times during chip making. Since 2021, Entegris also sold pipeline materials , optics polishing , and biocide units that

Tailoring the Wettability and Substrate Adherence of Thin Polymer Films with Surface-Segregating Bottlebrush Copolymer Additives.

We developed "reactive" bottlebrush polymers based on styrene (S) and t-butyl acrylate (tBA) as additives for polystyrene (PS) coatings. The bottlebrush polymers spontaneously bloom to both the air and substrate interfaces during solution casting. While neat PS films are hydrophobic and poorly adhere to the native oxide on clean silicon wafers, the hydrophilicity and substrate adherence of bottlebrush-incorporating PS films can be tailored through the thermally activated deprotection of tBA to produce acrylic acid (AA) and acrylic anhydride (AH). A critical design parameter is the manner by which tBA is incorporated into the bottlebrush: When the bottlebrush side chains are copolymers of S and tBA, the extent of deprotection is extremely low, even after prolonged thermal annealing at elevated temperature. However, when the bottlebrush contains a mixture of poly(t-butyl acrylate) (PtBA) and PS side chains, nearly all tBA is converted to AA and AH. Consequently, using the "mixed-chain" bottlebrush design with thermal processing and appropriate conditioning, the water contact angle is reduced from over 90° on unmodified PS down to 75° on bottlebrush-incorporating PS films, and the substrate adherence is improved in proportion to the extent of tBA deprotection.

Tuning Ice Nucleation by Mussel-Adhesive Inspired Polyelectrolytes: The Role of Hydrogen Bonding

Tuning Ice Nucleation by Mussel-Adhesive Inspired Polyelectrolytes: The Role of Hydrogen Bonding

Tuning the Properties of Surface-Anchored Polymer Networks by Varying the Concentration of a Thermally Activated Cross-Linker, Annealing Time, and Temperature in a One-Pot Reaction

We investigate the properties of surface-anchored polymer networks created via one-pot synthesis using thermally active 6-azidosulfonylhexyltriethoxysilane (6-ASHTES). 6-ASHTES is a bifunctional gelator that undergoes cross-linking and surface-anchoring reactions when annealed above 100 °C. We employ a poly(vinylpyrrolidone) (PVP) with different molecular weights (10–1300 kDa) as a model system to examine the effect of 6-ASHTES concentration, annealing time, and annealing temperature on gel formation. A thin film of PVP/6-ASHTES mixture is deposited on a clean silicon wafer and annealed to form network layers. Spectroscopic ellipsometry measures the film thickness of the cross-linked layers from which the gel fraction and swelling ratio are determined. The gel fraction of PVP in the network can be “dialed in” by varying the annealing time, temperature, and concentration of 6-ASHTES in the PVP/6-ASHTES mixture. We use a simple Monte Carlo simulation model to describe cross-linking as a function of cross-linker concentration, reaction rate, reaction time, and polymer length. The trends obtained from the model simulations are in qualitative agreement with the experimental data.

Terahertz generation and detection of 1550-nm-excited LT-GaAs photoconductive antennas

Terahertz generation and detection is the key means to explore terahertz spectrum, one of which is the application of photoconductive antenna. In this study, a low-temperature gallium arsenide (LT-GaAs) epitaxial wafer antenna and an LT-GaAs thin-film antenna were fabricated. The LT-GaAs epitaxial wafer antenna was fabricated using an epitaxial wafer composed of LT-GaAs, AlAs,GaAs, and semi-insulating GaAs. An LT-GaAs thin film was obtained by etching the AlAs layer in the epitaxial wafer and then transferring it to a clean silicon wafer to fabricate the LT-GaAs thin-film antenna. The LT-GaAs epitaxial wafer and thin-film antennas were used as the generation and detection antennas, respectively. The two antennas were directly aligned at a distance of 2 mm from each other and placed into a self-made measurement system for detection. A THz spectrum of approximately 2.5 THz was obtained under 1550-nm laser excitation, thus verifying the antenna performance.

Development of methodology for determining the isotopic composition of boron in powder and solid nuclear materials using secondary ion mass spectrometer

A method has been developed to determine the isotopic composition of boron (10B/11B) in powder and solid nuclear materials using secondary ion mass spectrometry (SIMS). Isotopic composition of boron in standard sample matrices such as H3BO3, B2O3, B4C (powder) and TiB2 (solid alloy) were measured by the method and compared with the isotopic composition determined from thermal ionization mass spectrometer. Powder samples were ultrasonicated in Milli-Q water and the solutions/slurry obtained were deposited on cleaned silicon wafers, dried under halogen lamp and analysed by SIMS whereas solid alloy sample TiB2 was directly analysed after mechanical polishing and cleaning. Detailed analyses have been carried out using both oxygen and cesium primary ion beams under different analysis conditions. Various elemental and molecular secondary ions were monitored for determining the isotopic composition of boron present in the samples. Standard of boron, NIST-SRM-951 sample was utilized for determining the instrument bias correction factor for different primary beam analysis conditions. The determined instrument bias correction factor was then utilized to measure the isotopic composition of boron in other samples. Surface distribution analysis was also carried out to determine the isotopic distribution of boron deposited on Si wafers. Determination of boron isotopic ratio in refractory nuclear materials (B4C, TiB2) using this method requires minimal sample preparation and avoids commonly used complex dissolution process.

Focused ion beam preparation of microbeams for in situ mechanical analysis of electroplated nanotwinned copper with probe type indenters

SummaryA site‐specific xenon plasma focused ion beam preparation technique for microcantilever samples (1–20 µm width and 1:10 aspect ratio) is presented. The novelty of the methodology is the use of a chunk lift‐out onto a clean silicon wafer to facilitate easy access of a low‐cost probe type indenter which provides bending force measurement. The lift‐out method allows sufficient room for the indenter and a line of sight for the electron beam to enable displacement measurement. An electroplated nanotwinned copper (NTC) was cut to a 3 × 3 × 25 µm microbeam and in situ mechanically tested using the developed technique. It demonstrated measured values of Youngs modulus of 78.7 ± 11 GPa and flow stress of 0.80 ± 0.05 GPa, which is within the ranges reported in the literature.Lay DescriptionIn this paper a site specific method is present for making particularly small mechanical tests samples, of the order of 100th the size of a human hair. These small samples can then be used to determine the mechanical properties of the bulk material. Copper with a nano twinned grain structure is used as a test medium.Ion milling was used to cut the sample to shape and a micro probe was used for mechanical testing. Ion milling can cut away very small volumes of material as it accelerates ions at the surface of the sample, atomically machining the sample. Micro probes are a cost‐effective small‐scale load measurement devices, however, they require a large area for accessing the sample. The indenter requirements are a problem when making you samples with ion milling as ion millers are best at making small cuts. Our aim was to design a cutting strategy which reduces the amount of cutting required while allowing samples to be fabricated anywhere on the sample.We used a chunk lift out technique to remove a piece of material which is then welded to a wafer of silicon this gives sufficient space around the sample for ion milling and testing. The additional space allowed easy access for the probe. A 3 × 3 × 10 µm micro cantilever beam was cut out from copper, this beam was then bent. The force from bending and distance bent was measured and converted into Youngs modulus which is a measure of flexibility. The modulus value measured was comparable to the values reported in other papers.

JSR plans big facility in US

The US semiconductor industry may be mature, but don’t tell that to Japan’s JSR and several other foreign chemical companies that are investing in new US facilities to produce key raw materials for the electronics industry. JSR says it will spend about $100 million to build a facility in Hillsboro, Oregon, that produces advanced formulated cleaning products used to clean circuit-covered silicon wafers between production steps such as lithography and etching. Set to open in 2020, the facility will mark JSR’s entry into the “advanced cleans” market, says Mark Slezak, president of JSR Micro. Today, JSR Micro mainly produces materials for photolithography, but Slezak says the firm’s US semiconductor industry customers asked it to bring its quality-management and technical skills to the advanced cleans market as well. Doing that locally will allow the company to have more control over logistics and raw material supply. Hillsboro is home to Intel’s largest

Calibrating lateral displacement sensitivity of AFM by stick-slip on stiff, amorphous surfaces

We calibrate the lateral mode AFM (LFM) by determining the position-sensitive photodetector (PSPD) signal dependency on the lateral tip displacement, which is analogous to the constant-compliance region in normal-force calibration. By stick-slip on stiff, amorphous surfaces (silica or glass), the lateral tip displacement is determined accurately using the feedback loop control of AFM system. The sufficiently high contact stiffness between the Si AFM tip and stiff, amorphous surfaces substantially reduces the error of PSPD signal dependency on the lateral tip displacement. No damage or modification of the AFM probe is involved and only a clean silicon or glass wafer is needed.

Effect of pyramidal texturization on the optical surface reflectance of monocrystalline photovoltaic silicon wafers

In this study, monocrystalline p-type Czochralski silicon wafers having dimension 127 × 127 mm2, thickness 200 μm, and plane (100) were textured to optimize the surface reflection for the fabrication of efficient solar cell. Properly cleaned silicon wafers were textured with the systematic variation of the etching time and chemical concentration (KOH and IPA) at 70 °C temperature. According to field emission scanning electron microscope (FESEM) images and surface reflection measurement (SRM) data, the wafer textured with 10 min etching time and the wafer textured with 1 g of KOH concentration, both showed the similar minimum optical reflectance of 15.08%. This lower reflectance was due to the formation of uniform pyramidal structure on the wafer surface. Moreover, the wafer surface textured with 7 ml isopropyl alcohol (IPA) showed the lowest surface reflectance of 13.59% because of the formation of more uniform pyramidal structure. The most effective pyramidal structure for fabricating efficient solar cell was found for 10 min etching with optimum chemical recipe of KOH: IPA: H2O = 1 g: 7 ml: 125 ml.

(Invited) Drying Patterns from Nanofluid Droplet Evaporation

Droplet evaporation has received more attention for the applications including concentrating chemicals, coating, printing, spraying, drying, painting, biomedical sampling, etc. Deposition pattern form the evaporative colloidal droplet has many applications in the industrial applications. The process to form the configuration in the drying droplet has been investigated with simulation and experiments. Experimentally, the suspensions of colloidal droplet with the particle size at nano- and micro-scale nanoparticles in the deionized water were prepared. The suspensions are carried out by well stirring first and then putting in an ultrasonication bath to ensure the even initial dispersion of the particles in the water. The clean silicon wafer was used as a substrate for the colloidal sessile droplet drying. Right after the suspensions were prepared, we placed a tiny sessile droplet to dry in the open conditions. The drying patterns were directly recorded with the optical microscope. The formation of branched particle aggregation structures was observed during the droplet evaporation. The experiments demonstrated the dried patterns such as finger, coffee ring, uniform coverage and the combined structures. We have applied the kinetic Monte Carlo model and the diffusion-limited aggregation simulation to explain the self-assemble processes. A lattice-gas Kinetic Monte Carlo (KMC) is developed to explain the of the finger structure while the diffusion-limited aggregation simulation is development to explain the transition from the coffee ring to uniform coverage. The mathematical models control the variables which indicate the presence of liquid, particle or substrate in cells of the cubical lattice. The simulation domain mimics the shape of a sessile nanofluid droplet. The particle, liquid, vapor interaction, and the other factors are considered. The experiments can be reflected by the simulations.

ToF‐SIMS characterization of glyoxal surface oxidation products by hydrogen peroxide: A comparison between dry and liquid samples

As one of the simplest volatile organic compounds, glyoxal and its oxidation products were considered to be important precursors to aqueous secondary organic aerosol formation. Herein, we analyzed products from glyoxal oxidation by hydrogen peroxide in dry and liquid samples using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). ToF‐SIMS spectra and spectral principal component analysis (PCA) were used to investigate surface oxidation products. Dry samples were prepared on clean silicon wafers. Liquid samples consisting of glyoxal and hydrogen peroxide (H2O2) were introduced to a vacuum compatible microfluidic reactor prior to UV illumination or dark aging followed by in situ liquid SIMS analysis. A number of reaction products were observed in both dry and liquid samples; different oligomers and carboxylic acids could be formed depending on reaction conditions. In addition, hydrolyzed products were observed in the liquid samples, but not in the dry samples. Although dry samples reveal some products of the aqueous process, they are not fully representative as results from those of the aqueous samples. Our findings suggest that the ability to characterize the liquid surface reaction products provides more realistic information of the reaction products associated with aqueous secondary organic aerosol formation in the atmosphere. Meanwhile, the high mass resolution spectra from the dry sample SIMS measurement are helpful to identify oxidation products in the liquid samples.

An X-ray spectroscopy study of CdS nanoparticles formed by the Langmuir–Blodgett technique on the surface of carbon nanotube arrays

The composition and electronic structure of cadmium sulfide (CdS) nanoparticles formed by the Langmuir–Blodgett (LB) technique on clean silicon wafers and the surface of vertically aligned carbon nanotube (CNT) arrays are studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The samples were annealed in a vacuum at 175 °C and 225 °C to remove the organic matrix of the LB film. From the analysis of the XPS data the increased concentration of sulfate groups on the surface of CdS nanoparticles formed on CNTs and the electron density transfer from CdS to CNTs are determined. An increase in the LB film annealing temperature causes an increase in the degree of crystallinity and the CdS crystallite size and a decrease in the photoluminescence intensity of a CdS–CNT hybrid.

High quality factor superconducting coplanar waveguide fabricated with TiN**Project supported by the the NKRDP of China (Grant No. 2016YFA0301802) and the National Natural Science Foundation of China (Grant Nos. 91321310, 11274156, 11504165, 11474152, and 61521001).

We fabricated TiN coplanar waveguides using standard lithography techniques followed by ICP etch. In order to achieve high quality factor, we investigated the film growth by choosing different deposition conditions for various substrates. Quality factors of waveguide resonators were measured at 20 mK in both high and low microwave power limits. An inner quality factor of several million was achieved at high power limit for a predominantly (200)-oriented TiN film which was grown on HF cleaned silicon wafer. A quality factor of larger than one million was achieved at high power limit for TiN film grown on sapphire.

Tribological influence of a liquid meniscus in human sebum cleaning

Abstract The interaction of surfactants in solution with hydrophobic materials is at the root of the process of detergency. Lipid containing micelles are formed in solution, and through water rinsing, these structures are washed out from the surface. The presence of air in the solution and the formation of foam add complexity to the system due to the increased proportion of water interfaces in contact with the surface. The latter situation is more difficult to understand. In this work, we propose, as a first step, to explore the role of the interfaces in cleaning silicon wafers previously coated with a model lipid mixture representing human sebum has been investigated. It turns out that the presence of interfaces enhances the cleaning efficiency. The effect of altering the surface properties of the silicon wafer was also investigated and it was found that changing the contact angle of the wafer brought a very strong effect on the cleaning efficiency.

Automated and inexpensive method to manufacture solid- state nanopores and micropores in robust silicon wafers

In this work an easy, reproducible and inexpensive technique for the production of solid state nanopores and micropores using silicon wafer substrate is proposed. The technique is based on control of pore formation, by neutralization etchant (KOH) with a strong acid (HCl). Thus, a local neutralization is produced around the nanopore, which stops the silicon etching. The etching process was performed with 7M KOH at 80°C, where 1.23µm/min etching speed was obtained, similar to those published in literature. The control of the pore formation with the braking acid method was done using 12M HCl and different extreme conditions: i) at 25°C, ii) at 80°C and iii) at 80°C applying an electric potential. In these studies, it was found that nanopores and micropores can be obtained automatically and at a low cost. Additionally, the process was optimized to obtain clean silicon wafers after the pore fabrication process. This method opens the possibility for an efficient scale-up from laboratory production.

シリコンウエハへの電解硫酸の利用

シリコンウエハへの電解硫酸の利用

Vertical orientation of solvent cast nanofilled PS-b-PEO block copolymer thin films at high nanoparticle loading

We demonstrate selective dispersion of photosensitive electron acceptor phenyl-C61-butyric acid methyl ester (PCBM) in cylinder forming polystyrene-b-poly (ethylene oxide) (PS-b-PEO) block copolymer (BCP). Neat PS-b-PEO is structurally robust to forming vertically oriented nanoscale morphology of PEO cylinders in the PS matrix directly after solvent casting. Varying amounts of PCBM nanoparticles were mixed with PS-b-PEO BCP in solvent mixtures and films were spin cast on UV/ozone treated clean silicon wafers. We studied in detail the BCP morphology orientation effect of different solvents and solvent mixtures for varying PCBM loading (ϕPCBM) in the films, range from 0 to 50 weight percent relative to the BCP. The key accomplishments of this work include vertical orientation control even at large concentration of PCBM ∼30% (w/w) particles relative to polymer mass and preferential segregation of PCBM in PS block via mixed solvent strategy which otherwise is difficult to realize due to segregation of PCBM on polar substrate. We explain the preferential dispersion of particles in films by demarcating limits in terms of critical Hansen solubility parameter. This value is close to the percolation threshold of PCBM, so a conducting polymer matrix can be expected, especially when it is partitioned preferentially in the matrix PS domain. We report changes in PEO cylinder diameter, cylinder center-to-center distance with PCBM incorporation into PS matrix, change of film thickness with overall PCBM incorporation and root mean square roughness of the film surface, for a range of casting solvents, solvent mixture compositions and ϕPCBM. Notably, the film thickness increased as the PCBM content in film was increased for same processing condition, so that domain swelling by nanoparticles was self-adjusting with film thickness increment.

Fabrication of Nanostructure-Based Copper Oxide Biosensor

The purpose of this paper is to give a review of the fabrication of nanostructure-based copper oxide biosensor. This paper briefly covers processes from silicon wafer cleaning, oxidation process, silicon nitride deposition, aluminum metal deposition, pattern transfer, copper oxide sol-gel preparation and coating and lastly IV testing with the results expected from the completed device.Keywords: Nanostruture, copper oxide, biosensor, sol-gel, current-voltage testing.

Surface morphology of F8BT films and interface structures and reactions of Al on F8BT films

The surface morphology and molecular orientation of -conjugated polymers, along with the chemical interaction and electronic structure at the interface between metals and these polymers, strongly affect the performance of the polymer-based organic electronic and optoelectronic devices. In this study, atomic force microscopy (AFM), synchrotron radiation photoemission spectroscopy (SRPES), and near edge X-ray absorption fine structure (NEXAFS) have been used to in situ investigate the morphology, structure, and molecular orientation of spin-coated poly(9,9-dioctylfluorene-co-benzothiodiazole) (F8BT) films and their interaction with the vapor-deposited Al metal. F8BT films were prepared by spin-coating the F8BT chloroform solution onto clean gold-coated silicon wafer surfaces. The room temperature spin-coated F8BT film is rather flat, while mild annealing treatments (120 ℃) below the glass transition temperature (Tg=130 ℃) lead to an apparent increase of surface roughness of F8BT film, which is helpful to effectively increase the contact areas between metals and F8BT. After 70 ℃ annealing in vacuum, the aromatic rings of F8BT preferentially stand more edge-on, making an average tilt angle of approximately 49 with the substrate, while the 9,9-dioctylfluorene unit (F8) and the benzothiodiazole unit (BT) nearly lie in the same plane. Upon vapor-depositing Al metal onto F8BT at room temperature, strong chemical interactions occur between Al and F8BT, as evidenced by the distinct changes of the S 2p, N 1s and C 1s spectra. Al reacts with S atoms more strongly than with N and C atoms in F8BT. In addition, obvious structural changes in valence band of F8BT are also observed during the Al deposition. Furthermore, Al dopes electrons into F8BT, leading to downward band bending, formation of interfacial dipole at the Al/F8BT interface, and partial occupation of lowest unoccupied molecular orbits (LUMO). However, no doping-induced gap states can be observed during the formation of Al/F8BT interface. Through the investigation of the core-level and valence band spectra evolution of F8BT together with the shifts of secondary electron cutoff during Al deposition, an energy level alignment diagram at the Al/F8BT interface is derived. The information gained through this study will help better understand the correlation between the interface structures of metal electrodes on semiconducting, -conjugated polymer materials and the performances of real polymer-based electronic and optoelectronic devices, which will in turn help develop the more efficient polymer-based organic devices.