Tag Archives: Solvent processing

Why Stainless-Steel Stations Are Needed for Solvent Processing

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During silicon wafer fabrication, BEOL (Back End of Line) processes may require solvent-based stations to ensure compatibility with semiconductor manufacturing steps. FEOL (Front End of Line) acid-based chemistry may not be suitable for BEOL finishing. Instead, stainless-steel stations with solvents such as acetone, IPA (Isopropyl Alcohol) or EDP (Ethylenediamine Pyrocatechol) complete wafer etching, stripping, and cleaning. Stainless steel is used for these stations because it is impervious to solvents and because it reduces the risk of fire when solvents are highly inflammable.

Why BEOL Wafer Fabrication Steps May Require Solvent-Based Stations

A wet bench FEOL fabrication starts by repeatedly cleaning, etching, and stripping wafers to build microscopic structures in the silicon. The common acid-based processes used include RCA clean, with chemicals such as hydrogen peroxide and hydrochloric acid; KOH etch, with potassium hydroxide; and Piranha clean, with sulfuric acid. As well as etching the silicon wafers, these chemicals remove both organic and metallic impurities from the surfaces of the wafers, leaving them completely clean and pure for the next process steps. The structures etched during these FEOL steps form the physical parts of the semiconductor components such as transistors.

In the BEOL process steps, the transistors and other components are interconnected and connected to plugs or sockets that interface with outside signals. The connecting paths are metallic, usually made of copper or aluminum, so that they can conduct electrical charges efficiently. Once the metallic paths are deposited on the silicon wafers, acid-based processes can no longer be used because the acidic chemicals damage the metallic paths. Instead, a solvent manufacturing process is used with solvents that are compatible with metals but can complete the silicon wafer processing and produce the final semiconductor components.

Solvent-Based Wet Benches Need Special Safeguards and Protection

The solvents used in wet bench stations are highly inflammable and operators have to be protected against being exposed to fumes or contact. Stainless steel stations using inflammable solvents have to be explosion-proof and satisfy the Class 1, Division 2, Group D explosion-proof standards. They should be designed with fire suppression and wired to the NFPA 70 and 79 standards. An emergency power off mushroom button with safety interlocks helps protect operators if something goes wrong and PVC safety shields help prevent accidental contact with the chemicals. An experienced wet bench manufacturer can ensure that these safety regulations are followed and that operating the solvent stations is as safe as possible.

Modutek’s Stainless Steel Solvent Stations Operate Safely and Meet Customer Requirements

With over 30 years of experience in wet process technology, Modutek designs and builds stainless steel solvent stations to operate safely and meet customer requirements. These stations are made of 304 stainless steel and are wired to the NFPA 70& 79 standards. Fire suppression is included and extensive customization is available.

Stations can be fully automated, semi-automatic, or manual. Fully automated stations reduce operator error and feature excellent repeatability, both for batch processing and for keeping variables constant over an extended period of continuous operation. Semi-automatic stations provide many of the benefits of fully automated operation but at a lower cost. Manual operation is ideal for testing or for prototypes. Once the process has been optimized with manual adjustments, automatic operation can reduce defects and improve facility performance. SolidWorks Simulation software is available to analyze the process and calculate chemical flows. The software can improve etching performance, improve yields and increase throughput.

On the performance side, Modutek stainless steel stations can operate with temperatures from thirty to one hundred degrees centigrade, heat up the bath at a rate of 2 degrees centigrade per minute, and maintain the temperature with an accuracy of plus/minus 1 degree centigrade. Heating elements are four-sided and a process temperature controller is available as an option.

Modutek’s Expertise in Wet Process Equipment

 Modutek designs and builds their own wet process equipment in-house using their own expertise and experience. Their wet bench equipment is designed to meet high quality standards, and are customized to meet specific customer requirements. Solvent-based stainless-steel stations deliver top performance for BEOL processing and Modutek can ensure the equipment meets specific customer needs. Contact Modutek for a free consultation to discuss your specific process requirements.

How Stainless-Steel Stations Provide Safe Solvent Processing

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How Stainless Steel Stations Provide Safe Solvent ProcessingSolvents used in semiconductor manufacturing can remove oils and organic contaminants from silicon wafers in preparation for further processing steps. Acetone, isopropyl alcohol (IPA) and ethylene diproxitol (EDP) are solvents commonly used to clean wafers, remove photoresists, and in pattern transfers for the creation of microscopic structures on the wafer. The solvents are inflammable and require special safety measures to reduce the risk of fire and explosion, and they have to be disposed of safely. Stainless steel wet benches incorporating stainless steel processing tanks are an ideal solution for safe processing with solvents.

Safety Requirements for Stainless Steel Wet Bench Stations

The safe operation of stainless-steel solvent stations has to include the following safety features:

  • fire suppression
  • fire fighting
  • protection against exposure
  • protection against leaks
  • safe disposal

Fire is one of the principal safety hazards because solvents or their vapors can catch fire and explode. Fire suppression measures can include electrical design limiting the potential energy of sparks so they can’t ignite solvents and designing equipment to Class 1, Division 2 specifications.

Firefighting equipment has to be able to extinguish fires, should they occur. For inflammable liquids such as solvents, gas-type fire systems such as those using carbon dioxide are needed. It’s critical to have corresponding safety protocols and procedures to ensure workers are evacuated before triggering the extinguishing gases because the firefighting gas displaces oxygen and could cause suffocation.

Many solvents are harmful when workers are exposed to them over extended periods, either through direct contact or through breathing the vapors. A complete enclosure of the solvent processing tanks along with effective exhausts and leak detection limits the amount of solvent to which workers can be exposed.

Disposal of used solvents has to be carried out safely and according to environmental regulations. The disposal can be on-site if the facility has the corresponding capability, or the waste can be stored in a carboy for pick-up by a specialized disposal company.

Modutek Stainless Steel Wet Bench Stations are Safe and Customizable

Modutek stainless steel stations are made from 304 stainless steel and are available in fully automatic, semi-automatic, or manual versions. Dry to dry and fume hood designs are possible, and the stations feature casters and leg levelers. SolidWorks simulation software calculates the process flow characteristics and all design, assembly, and testing are carried out in-house. The stations can be built to the size and length required and extensive customization is available to exactly match customer requirements.

On the safety side, all stations are wired to the NFPA 70 & 79 standards and designed with fire suppression. Safety interlocks with emergency power off buttons are included. The station tanks have a one-inch lip exhaust and a continuous flow deionized water manifold. PVC safety shields are included and the stations have a nitrogen head case purge with Photohelic pressure interlocks. A Teflon nitrogen gun and deionized water hand spray are also included.

As a leading wet bench manufacturer, Modutek works closely with customers to determine how best to help them meet their objectives. Careful wet bench design can increase productivity and output while reducing costs. Modutek is focused on delivering wet bench equipment such as stainless-steel solvent stations using the best available materials and safe, high-quality designs.

With over 40 years of experience in the manufacture of wet benches and with the ability to carry out all design, assembly, and testing work in the company’s San Jose facility, Modutek is the ideal partner for semiconductor fabrication facilities and research labs. Modutek’s in-house experience allows for easy customization and safe execution of wet process semiconductor manufacturing projects of all kinds. Contact Modutek for a free consultation to discuss your specific solvent processing requirements.

Solvent Processing Using Stainless Steel Stations

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Solvent Processing Using Stainless Steel StationsManufacturing processes using volatile solvents have to be specially designed to minimize the risk of explosions or fire. Solvents such as acetone or alcohol are used to clean parts, dissolve materials and extract substances. Modutek’s stainless steel stations meet strict safety regulations that reduce the risk of ignition of the solvents or their vapors and they have additional features and interlocks in an integrated approach to operator safety. As a result, the stainless steel stations can be installed safely in both new and existing facilities for solvent processing.

Special Design Measures Ensure Safe Solvent Station Operation

Safe stainless steel solvent station operation depends on specific design measures that reduce the risk of fire or explosion. Modutek’s stations satisfy safety regulations and include design features that improve safety based on extensive experience in wet bench processing. Special safety design measures can include the following:

  • Electrical equipment runs on low voltages and weak currents to reduce the risk from sparks.
  • Electric wiring satisfies fire protection standards NFPA 70 and 79.
  • Overall station design satisfies hazardous location standards and is certified for Class 1, Division 2 environments.
  • The manufacturing process is monitored to detect dangerous conditions such as high temperature.
  • Liquid solvent waste is collected in carboys for controlled disposal.
  • Safety interlocks eliminate unsafe operation and shut down the process for unsafe conditions.
  • Automatic lid operation can seal off chemical containers.
  • Operators are trained for safe operation.
  • Access controls limit equipment operation to trained personnel.

How Stainless Steel Solvent Processing Stations Operate Safely and Reliably

Modutek’s Series SFa and Sa Stainless Steel Stations for solvent processes meet all the safety requirements of the applicable regulations. Made of electropolished stainless steel, the stations satisfy the National Electrical Code Class 1 Division 2 Group D standard for hazardous locations. The baths feature PVC safety shields, N2 head case purge and an auto lid option. They are designed for operator safety and prioritize safe containment and disposal of volatile solvents.

The SFa series station uses a temperature controlled re-circulating bath while the Sa series is constant temperature. The baths have a temperature control precision of plus/minus 1 degree centigrade, a heat-up rate of 2 degrees centigrade per minute and an operating temperature range of 30 to 100 degrees centigrade. Bath heaters are rated from 2 to 6 kW depending on the tank size. With precise temperature control and a fast heating rate, the baths can improve yield and produce high-quality process output.

In addition to the safety features and temperature control characteristics, the baths have multi-sided heating elements, a 360 degree overflow weir, operating interlocks, process control thermocouples and liquid level sensors. The tanks are available in standard sizes from about 8 inches to 24 inches a side. Custom sizes are also available.

Modutek’s Can Provide Solvent Processing Stations to Satisfy Customer Requirements

With 40 years experience in designing wet benches for semiconductor manufacturing, Modutek supplies stations made with high-quality materials designed for safety, ease of use and reliable operation. As a leading wet bench manufacturer, Modutek is constantly innovating to incorporate the latest advancements in its wet process equipment including its solvent processing stations.

Modutek can examine solvent processing needs and recommend stations for specific applications. A complete line of standard baths and the ability to customize as required means the company can build solvent processing stations to meet special customer needs. Modutek builds all its own equipment and designs and writes its own software in-house. As a result, Modutek can give expert guidance on what is required and follow up with complete customer support and service for all its products. For a free quote or consultation to discuss your specific requirements contact Modutek at 866-803-1533 or email [email protected].