Nanotechnology

Semi-conductor industry

Semi-conductor industry

Carbon nanotubes are one the many products of nanomanufacturing. These nanotubes are slowly replacing silicon transistors and are expected to entirely substituting the latter. Tiny transistors known as gate-all around transistors are now made out of silicon nanowires, with diameter close to 1 nanometer.

According to United States Environmental Protection Agenecy (US EPA), the manufacture of semi-conductors is divided into three categories: (1) crystal wafer growth and preparation; (2) semi-conductor fabrication (also referred to as wafer fabrication) and (3) final assembly. The semi-conductor fabrication processes are typically performed in a clean room and include the following steps: oxidation; lithography, etching, doping (vapor phase deposition and ion implantation), and layering (metallization).

In semi-conductor manufacturing, crystal wafer growth manufacturing usually require Class 1 to class 10 cleanroom, while the semi-conductor fabrication needs a Class 10 000 cleanroom. A Class 100 000 cleanroom usually for the final assembly.

Soft Cleanroom Capsule

Soft Capsule® Soft Wall Cleanroom

These equipment can provide a Class 100, Class 1 000 and Class 10 000 environment. This is recommended from the wafer fabrication to the final assembly.

Ceiling Laminar Airflow

Ceiling Laminar Airflow Units (CLAF)

These are more cGMP compliant unit that provides a better containment scheme compared from Soft Wall Soft Cleanroom Capsule since it can provide a unidirectional airflow. It is customizable according to the customers' preferences in terms of dimensions.

Solar Cells

The researchers in Michigan Technological University are currently developing solar cells made out of graphene coated with zinc oxide nanowires. This method is believed to allow low cost and flexible production of solar cells.

A specific method known as Aerotaxy permits the growing of semiconducting nanowires on gold nanoparticles. The gold nanoparticles are to replace the silicon substrate.

While at Princeton University, the researchers have innovated a solar cell that uses a 30 nanometer thick gold nanomesh to eliminate energy losses due to the reflection of light. Along with the gold nanomesh is an active layer of the same kind that is thinner than the wavelength of light. This combination eventually conserves light energy by trapping mechanism.

The resonance effect allows sunlight to be concentrated on nanowire while a cost-effective solar cell intended to produce hydrogen is currently being developed using iron oxide nanoparticles. A solar cell that is estimated to have 70 percent transparency to visible light is made from combining silver nanowires, titanium dioxide nanoparticles. This combination mainly absorbs infrared light.

Most western countries are considering nanoparticles as new chemical entities. The US EPA requires most nanomaterials such as but not limited to fullerenes, quantum dots, and carbon nanotubes to undergo several review processes to ensure safety.

However, no profound and concrete data in terms of the minimum and maximum exposure levels of an individual specific to nanometerials has been set. In return, manufacturing industries, research institutions, and even universities have established and suggested specific Occupational Exposure Levels (OELs). For example, a threshold value for Carbon Nanotubes has also been set in Switzerland in 2011 by the Swiss National Accident Insurance Fund at 0.01 fibres/mL.

Concern Category Characteristics of nanoparticles Examples
High Poorly soluble or insoluble (water solubility < 100 mg/L) Some carbon nanotubes
Medium-High Poorly soluble or insoluble (water solubility < 100 mg/L) or nanoparticles with specific toxicity.

Nano-silver

Gold nanoparticles

Zinc oxide nanoparticles

Medium-Low Poorly soluble or insoluble nanoparticles with no specific toxicity.

Carbon black

Titanium Dioxide

Low Soluble nanoparticles

Sodium Chloride nanoparticles

Lipid nanoparticles

Flour nanoparticles

Amorphous silica

A laboratory fume hood is a type of ventilation system that primarily functions to provide personnel protection against toxic fumes, vapors and dust. Its secondary function includes protection against chemical spills, runaway reactions and fires by acting as a physical barrier.

Frontier Fume Hood
Acela Fume Hood
Ascent Fume Hoods

Another alternative engineering controls are the use of glove boxes and other enclosed systems.

General Processing Platform Isolator

Aseptic Containment Isolator (ACTI)

Rechargeable Batteries

The primary problem for rechargeable batteries is the repeated shrinking and expanding when charging and discharging takes place. This can lead to the batteries' short life because of the frequent shedding of the skin layer that consumes lithium irreversibly.

The Massachusetts Institute of Technology (MIT) together with Tsinghua University in China have developed a battery that can shrink and expand without affecting the size of the shell. They have created an electrode made of nanoparticles with a solid shell.

The use of nanoparticles with an aluminum yolk and a titanium dioxide shell has proven to be "the high-rate champion among high-capacity anodes,"" the team reports.

The use of nanocrystalline materials and nanotubes have improved the life and the charge/discharged rates of rechargeable batteries. The graphite on the usual lithium-graphite-electrodes is now being replaced by nanotubes. Since nanotubes have a higher surface area, it can incorporate more lithium compared with graphite, resulting to an extension of battery life.

Device Displays

Device displays also make used of nanotechnology through organic light-emitting diodes (OLED). Organic materials are said to emit light when fed by an electric current. The provision of OLEDs makes it possible to develop a more lightweight, ultra bright, and power-saving device displays compared with the conventional ones.

There are three main manufacturing processes for OLEDS.

  • Vacuum deposition or vacuum thermal evaporation (VTE) - In a vacuum chamber, the organic molecules are gently heated (evaporated) and allowed to condense as thin films onto cooled substrates. This process is expensive and inefficient. (Freudenrich, 2018)
  • Organic vapor phase deposition (OVPD) - In a low-pressure, hot-walled reactor chamber, a carrier gas transports evaporated organic molecules onto cooled substrates, where they condense into thin films. Using a carrier gas increases the efficiency and reduces the cost of making OLEDs. (Freudenrich, 2018)
  • Inkjet printing - With inkjet technology, OLEDs are sprayed onto substrates just like inks are sprayed onto paper during printing. Inkjet technology greatly reduces the cost of OLED manufacturing and allows OLEDs to be printed onto very large films for large displays like 80-inch TV screens or electronic billboards. (Freudenrich, 2018)

Hybrid fabrication processes which are taking place in cleanrooms include vacuum deposition, screen printing, and chemical deposition. Vacuum technology processes include vapor deposition, sputtering, and other vacuum techniques for depositing metals and dielectric materials on substrates.

Thin-film circuitry can be deposited and etched to tolerances less than 0.001 inches, while thick films are limited to about 0.005 inches as screened, and 0.002 inches if etching techniques are used after screening. Contamination as small as 1-10 m, or 0.001 inches would probably result in an open circuit in a thin film substrate.

Cleanroom Air showers

Cleanroom Air showers

Air showers are a part of most clean room designs. While they were designed to blow dust off the surface of uniforms before wearers enter the cleanroom, military studies suggest that 1 m particles may actually be driven into the fabric by the shower.

The use of ceiling filters in vertical airflow systems allows more flexibility in cleanroom design, allowing the whole room to be used for critical operations. The air either is exhausted or is recirculated through floors or sidewalls

Modular Clean Room

Modular Clean Room (MCR)

Lowering capital costs and stabilizing the process has always been a problem area when planning a Class 100 manufacturing facility. Typically, a one-to two-year construction cycle is involved during which process normally changes. Commonly, the end result is large, unexpected cost overrun necessitated by process changes. Thus, one way to keep costs under control while still providing an extremely clean manufacturing environment to critical portions of the process which require such control is to integrate MCRs and the normal factory into a single working unit.

LED Lightings

Electroluminescence (EL) is both an electrical and optical phenomenon used in the lighting industry in response to an electric current or to a strong electric field. Currently, EL is the most preferred technique for the development of LED lightings.

Light-emitting diodes (LEDs) are navigating towards the modification of emission intensities, colors, and directionalities. Hence, the introduction of metallic nanostructures are one of the most useful method which controls light emission without the requirements of secondary optical components.

The use of LED is prevalence since this technology offers higher efficiencies, longer lifetimes, fast switching, robustness and compact size. (Lozano et.al., 2016)

According to United States Environmental Protection Agenecy (US EPA), the manufacture of semi-conductors is divided into three categories: (1) crystal wafer growth and preparation; (2) semi-conductor fabrication (also referred to as wafer fabrication) and (3) final assembly. The semi-conductor fabrication processes are typically performed in a clean room and include the following steps: oxidation; lithography, etching, doping (vapor phase deposition and ion implantation), and layering (metallization).

In semi-conductor manufacturing, crystal wafer growth manufacturing usually require Class 1 to class 10 cleanroom, while the semi-conductor fabrication needs a Class 10 000 cleanroom. A Class 100 000 cleanroom usually for the final assembly.

Soft Wall Cleanroom

Soft Capsule® Soft Wall Cleanroom

These equipment can provide a Class 100, Class 1 000 and Class 10 000 environment. This is recommended from the wafer fabrication to the final assembly.

Ceiling Laminar Airflow

Ceiling Laminar Airflow Units (CLAF)

These are more cGMP compliant unit that provides a better containment scheme compared from Soft Wall Soft Cleanroom Capsule since it can provide a unidirectional airflow. It is customizable according to the customers' preferences in terms of dimensions.

Biomedical

Diagnostic techniques, drugs, and prostheses and implants are the three main applications of nanotechnology in the biomedical field. Diagnostic sensors and "lab-on-a-chip" techniques for blood analysis and other samples, and for inclusion in analytical instruments for R&D on new drugs.

It is a common misconception that nanostructured materials automatically become new drug compounds, hence, some of them only becomes drug delivery vehicles. Because of the nanometer size of these materials, it can move easily inside the body. One example is the anticancer drug, Paclitaxel that is integrated with ABI-007, a new nanoparticle that is consisted of an engineered protein-stabilized particle that can move inside the body with ease.

Aside from drugs, cosmetics based on quantum dots are already emerging. Nanocrystalline materials such as zinc oxide for sunblock becomes one of the few cosmetics that started the trend.

Methods Employers Can Use to Reduce Worker Exposure to Nanomaterials

Because the research and use of nanomaterials continues to expand and information about potential health effects and exposure limits for these nanomaterials is still being developed, employers should use a combination of the following measures and best practices to control potential exposures:

Engineering Controls

  • Work with nanomaterials in ventilated enclosures (e.g., glove box, laboratory hood, process chamber) equipped with high-efficiency particulate air (HEPA ) filters.
  • Where operations cannot be enclosed, provide local exhaust ventilation (e.g., capture hood, enclosing hood) equipped with HEPA filters and designed to capture the contaminant at the point of generation or release

Administrative Controls

  • Provide handwashing facilities and information that encourages the use of good hygiene practices.
  • Establish procedures to address cleanup of nanomaterial spills and decontamination of surfaces to minimize worker exposure. For example, prohibit dry sweeping or use of compressed air for cleanup of dusts containing nanomaterials, use wet wiping and vacuum cleaners equipped with HEPA filters.

Personal Protective Equipment (PPE)

  • Provide workers with appropriate personal protective equipment such as respirators, gloves and protective clothing.

Medical Screening and Surveillance

  • Make available medical screening and surveillance for workers exposed to nanomaterials if appropriate
  • Review medical surveillance requirements under OSHA standards (e.g., Cadmium, Respiratory Protection.)

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