Safe Waste Gas Abatement in High-Tech Industries
The manufacture of powerful high-tech products like microchips, photovoltaic modules, flat screens, and Light Emitting Diodes (LEDs) requires highly complex, multistage manufacturing processes. Each production sub-step creates waste gases that have to be abated directly at their point of origin (Point-of-Use).
Reliable Waste Gas Abatement at the Point-of-Use
At DAS Environmental Expert our systems are as flexible and unique as our clients. Currently we offer waste gas abatement technology in four process groups: The combination of burner and scrubber in one system is DAS Environmental Expert’s specialty. The ESCAPE and STYRAX systems are part of this product group. The LARCH product family is used for process waste gases with high hydrogen content. The gas scrubbers of the AQUABATE product group and SALIX gas scrubbers wash harmful water-soluble substances from process waste gases. The electrostatic dust collectors of the EDC product line utilize an electrical field to remove fine particles (micro and nanoparticle) from waste gases.
The electrostatic condensate separators of the JUNIPER series use the same principle to intercept and remove Volatile Organic Compounds (VOCs) from exhaust streams. DAS Environmental Expert cultivates a close collaboration with its clients. We provide cost-effective processes for reliable and safe waste gas abatement, and we develop and enhance our systems. When a client’s technologies change, we adapt and adjust our waste gas technology according to the client’s needs.
Chemical Vapor Deposition (CVD) is used to deposit thin films onto the surface of a substrate. The films develop through a chemical reaction that takes place between film components that exist in the gas. When the source substance is a metal organic compound, the process is called Metal-Organic Chemical Vapor Deposition (MOCVD).
CVD processes are used in the semiconductor industry to manufacture defined thin films from diverse metals, silicon nitride, silica and polysilicon. Among the gases typically employed are silane, ammonia, TEOS (tetraethyl orthosilicate), and nitrogen trifluoride. The DAS Environmental Expert systems UPTIMUM, and STYRAX product lines have been specifically designed to treat waste gases from CVD processes.
MOCVD processes are used in the semiconductor industry and to manufacture Light Emitting Diodes (LED). Typically, hydrogen-and ammonia-containing waste gases require treatment. DAS Environmental Expert has developed the Point-of-Use system LARCH that specifically abates large amounts of these process gases.
In recent years Transparent Conductive Oxides (TCO) have gained large economic significance. These translucent thin films are important components of flat screens and thin film solar modules; the thin films are manufactured through thermic evaporation or specific CVD processes. Large amounts of the waste gases resulting from these processes can be abated directly at Point-of-Use through the burner-scrubber technology featured in the UPTIMUM system.
Etching ablates material from a surface by means of corrosive substances. Because it is characterized by high precision, the process is used particularly in the semiconductor industry and for the manufacturing of Micro Electrical Mechanical Systems (MEMS). Non-ablated structures are protected from the chemical etching through a specific photoresist. The chip manufacturing industry uses both wet chemical and dry etching processes, such as plasma etching and reactive ion etching. The waste gases resulting from these processes typically contain diverse fluorine compounds. The burner-scrubber technology of DAS Environmental Expert ESCAPE and STYRAX product lines efficiently treat these process waste gases.
The semiconductor industry uses epitaxy to deposit crystalline films or overlayers onto a carrier substrate. The layers are characterized by their high purity and can be doped with a better precision than common doping methods. The films are manufactured either through specific chemical and physical vapor deposition processes, their hybrid forms, or with liquid-phase epitaxy. The waste gases from these processes can contain hydrogen, dichlorosilane, and germane. The DAS Environmental Expert scrubbers of the AQUABATE product line and the burner-scrubbers of the ESCAPE and STYRAX line provide safe and reliable abatement options, according to waste gas contents.
Following certain production steps, the manufacturing of semiconductor chips requires the wafers to be cleaned. To accomplish this, chip manufacturers, particularly those of 300 mm wafers, use single wafer cleaning. This process puts single wafers into a fast rotating motion and subsequently wets them with cleaning liquids.
According to the wafer’s impurities, diverse cleaning processes are used, utilizing either acidic or alkaline chemicals or solvents like acetone, ethanol and isopropyl alcohol. After each cleaning step, the disks are rinsed in ultrapure water. Subsequently, the wafers are dried residue-free.
The cleaning agents used in the process create an exhaust that contains residue, either in gaseous form or as droplets. With the gas scrubber SALIX, DAS Environmental Expert provides a reliable system that vacuums and purifies these contaminated exhausts.
Carbonaceous compounds that easily evaporate are called Volatile Organic Compounds (VOC), with some compounds that evaporate to a gaseous state at room temperature. Both the semiconductor and solar industries use such substances as auxiliary materials. VOC often have an unpleasant odor and can be toxic and harmful to the environment.
VOC emissions can also cause substantial damage to the manufacturing plant. When VOC condensate in exhaust systems, the condensate can escape through leaks and pose a health risk to employees, or flow back into the manufacturing systems and cause fires. DAS Environmental Expert designed the system JUNIPER to avoid such risks, and safely remove these hydrocarbons from the exhausts of manufacturing plants.
Many waste gas abatement processes require the extraction of dusts. Dusts from waste gases are very fine solid particles that, stirred up, can remain suspended in the air over extended periods of time. Particles with a diameter of more than ten micrometers are considered coarse dust and are caught by the nasal hairs or mucous membranes of the nasopharyngeal cavity. Dusts of particles smaller than ten micrometers (PM10) are called particulate matter, and if inhaled, can reach deeply into the lungs by way of the trachea and bronchial tubes.
Particles sized smaller than 2.5 micrometers are called fine particles (PM2.5) and sizes smaller than 0.1 micrometers are called ultrafine particles. Particulate matter comprised of PM10, PM2.5 and ultra fine particles are difficult to treat because the micro particles pass with the exhaust through the gas scrubber and separator without getting caught in the scrubbing liquid.
DAS Environmental Expert developed the electrostatic dust collector EDC product line specifically to collect such particulate matter. Our EDC systems are used in the semiconductor, solar and flat screen industries, and meet environmental regulations in LED-manufacturing; particularly in regards to arsenic, where the system guarantees meeting the legally prescribed and extremely low emission limit values.
Consulting and Technology Selection
The selection of the appropriate technology is carried out by our application specialists after analyzing the situation on site. Information about the process tool, vacuum pump, gas types and flows as well as the available operating materials are decisive.
In order to ensure a long-term runtime and tool availability, our service and technical support are available on demand or on-site as soon as the system is commissioned.
Dr. Christian Kuhne
Director Sales Global