How Precision Parts Cleaning is Supported with Automation

Precision cleaning of industrial parts can be time-consuming and expensive. Manual brushing and scraping are labor-intensive and can result in injuries to the workers or damage to the parts. Handling heavy parts from manufacturing equipment is often difficult, especially when they have to be placed in a chemical bath. The chemicals themselves are expensive and spills or errors in mixing can be dangerous.

When precision parts cleaning is automated, chemical use is clearly defined and waste is reduced. The automated system handles the parts so worker safety is improved. Workers can carry out other tasks while the automated system carries out the cleaning. In this way, automation can save time, reduce precision cleaning costs and improve cleaning performance.

Fully Automated Precision Cleaning Results in Consistent Cleaning Performance

The automated precision parts cleaning system is made up of the cleaning station, robotics, and automation. The cleaning station includes the cleaning tank, an enclosure, and the piping for the cleaning chemicals and solutions while the robotics handles the parts to be cleaned. The automation system runs the cleaning process and has an operator interface used to program the system and to observe the cleaning process.

Once the automation system is programmed for a cleaning application, the operator can place the parts to be cleaned in a basket. The robotics transfers the basket to the cleaning station and positions it for cleaning. The automation system goes through the programmed cleaning cycle, whether it involves di-water cleaning, megasonic cleaning, immersion, or other cleaning processes, adding chemicals and draining the baths as needed. Once the cleaning cycle is complete, the robotics removes the basket from the cleaning station and presents the clean parts to the operator.

Fully automated precision cleaning is especially valuable when the same or similar parts are cleaned repeatedly or when manufactured parts have to be cleaned before shipment. Sample parts can be cleaned and checked to see whether the cleaning performance is adequate. Once the automatic cleaning is satisfactory, the program can be run repeatedly to give consistent results. A series of parts are cleaned exactly the same way and present the same level of cleanliness.

The Modutek Automated Precision Cleaning Stations Support Customer Requirements

Modutek offers a fully automated solution for precision industrial cleaning of small, mid-sized, and large parts, usually made of metal or glass that typically weigh up to 45 pounds. A 2 X 2-foot basket can hold one or more parts and has a payload of 100 pounds. Baskets with payloads of 150 pounds or more can also be supported. The basket takes the parts to be cleaned and places them in position inside the cleaning station. Once started, the cleaning process runs without operator intervention until the cleaning cycle is complete and the basket brings out the clean parts for operator pickup.

A touch screen can show the progress of the cleaning process and the operation of the station. The touch screen can also be used for configuring the automated cycles and for operating the cleaning station. Normally, once the cleaning cycle has been programmed, the station will run until the clean parts are ready to be taken away. Modutek’s precision cleaning stations are ideal for precise cleaning of industrial parts that are not easily manipulated for manual cleaning. The automation and the robotic part handling equipment reduce the possibility of operator error and worker injury. Modutek’s industrial parts cleaning equipment can be designed and built to meet your specific application requirements.

Modutek is a leading semiconductor equipment manufacturer, that has in-house experience and expertise in designing equipment for wet processing and silicon wafer cleaning applications. The company can advise customers on the type of automated cleaning systems needed to meet manufacturing requirements. Contact Modutek for a free consultation to discuss the specific cleaning needed for your industrial parts.

Innovative Table Top Units that Support Chemical Wet Processing

Research, proof of concept, or prototyping often require the production of single silicon semiconductors or a small number of functional units. Using a semiconductor manufacturing line for this purpose is expensive and lacks flexibility. Wet process manufacturing can be scaled back to reduce equipment size without losing functionality. Modutek has developed table top units that can carry out the most important silicon wet etching functions to produce small volumes of semiconductor products quickly and efficiently.

Modutek’s Table Top Units Support the Most Common Kinds of Chemical Wet Processing

The table top chemical wet processing units that are compact, self-supporting systems made up of a Teflon tank or stainless-steel solvent tank and a control box. The tanks are available as ambient or temperature-controlled models and can be static baths or recirculating baths with a filter. They support KOH etch, buffered oxide etch (BOE), solvent resist strip and they can be fitted out for other types of wet processing.

The temperature-controlled tanks feature fast temperature rise, uniform heating, and accurate temperature maintenance. Tanks have an all-Teflon fluid path, level, and temperature alarms, and a drain interlock. Their size makes them ideal for small batches, test units, or multiple versions of a basic design.

KOH Etch Using Modutek Table Top Units

KOH etching is widely used because it is relatively safe and easy to control. The concentration of the potassium hydroxide and the temperature of the bath are the key variables for determining the etch rate. Once the concentration is set, the table top units can control the temperature to get the desired etch rate. The rapid temperature rise speeds up the overall process and improves efficiency. The precision of the temperature control ensures that the etched cavities in the silicon wafer are exactly as required and provide for excellent repeatability.

The table top units are designed to minimize impurities and deliver high-quality output. Design changes in semiconductor structure are reliably carried out while the basic structures of the original design remain identical from one process run to the next.

The Table Top Units Can Handle Solvent Resist Strip

Solvents used in semiconductor manufacturing can remove resist, 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. Modutek’s table top system supplies all of this in an easy-to-install design package.

Sub Ambient Buffered Oxide Etch (BOE) with Table Top Units

The BOE process is used to etch thin layers of silicon dioxide or silicon nitride with hydrofluoric acid and a buffer. For sub ambient BOE, the table top units are fitted with a chiller/heater that permits an operation in the 10-to-60-degree centigrade range. The sub ambient filtered etch bath reduces acid consumption and delivers highly efficient filtration. The table top units feature a safe and reliable operation at a comparatively low cost.

Modutek Can Design Custom Units for Special Applications

As a leading manufacturer of silicon wet etching equipment, Modutek designs builds and tests their own products in-house. Modutek works closely with customers to develop innovative approaches that solve industry problems. Contact Modutek for a free quote or consultation for specialized equipment that meets your wet processing requirements.

Why Chemical Collection Carts are Needed for Chemical Handling

When high-volume chemical delivery systems are not needed because of small production volumes, chemical collection carts can provide safe chemical handling. Also known as chemical delivery carts or chemical pump carts depending on their role, these chemical carts can safely deliver chemicals to the process and remove them for disposal.

Safe handling of aggressive chemicals is especially important for small facilities that can benefit from the use of chemical collection carts. Labs, research centers and universities often have limited space and lack chemical treatment capability. Using chemical collection carts for the removal of used chemicals and safely delivering them to a specialized chemical treatment provider means small production sites don’t have to worry about adhering to disposal regulations.

Modutek’s Chemical Cart Characteristics and Features

Modutek’s chemical carts are designed for safety, ease of use, and flexibility. The incorporated on-cart holding tank can vary from 5 to 25 gallons and the carts can hold a 55-gallon drum in an optional configuration. The tanks are mounted on swivel casters with brakes and measure 18 inches wide, 36 inches long, and approximately 42 inches high.

With a three-eighths inch pneumatic pump and all-pneumatic operation, no electrical connection is required. Construction is white polypropylene with an all-Teflon fluid path and a stainless-steel option is available for solvent applications. The carts feature independent suction and discharge tubes and there is a high-level sensor with a pump interlock in the holding tank.

Operation of the carts for the dispensing of solvents, acids, or bases and the removal of waste chemicals is straightforward. The suction tube transfers chemicals from an external tank to the holding tank while the discharge tube drains holding tank chemicals and transfers them to an external container. A single pump cart can be used for multiple applications.

Chemical Collection Carts Are a Safe Way of Handling Chemicals

While still requiring manual operation, chemical pump carts can reduce the possibility of spills and accidents. With the use of carts, the transfer of chemicals between containers takes place in a controlled and structured fashion. Aggressive chemicals can be kept at a distance from the operators and workplace safety increases.

In normal use, the pump cart can be rolled up to the chemical processing station and can transfer the required chemicals. For chemical removal and disposal, for example, the suction tube of the cart can transfer the waste chemicals from the process tank to the cart holding tank. The cart can then be rolled out for chemical disposal.

Facilities that use chemicals for their production lines may have their own neutralization and disposal systems, but smaller facilities including universities and research labs often outsource chemical neutralization and disposal to specialized service providers. If the manufacturing facility neutralizes its own waste chemicals, the pump cart can transfer the collected waste from the holding tank into the neutralizing and disposal system. If an external service provider is used for chemical disposal, Modutek’s carts make it easy to ship the containers holding the waste.

The holding tanks on Modutek’s carts feature double containment for extra safety. If the waste chemicals are not neutralized on site, they are stored in a Department of Transport (DOT) approved container for pickup by the specialized chemical processing company. In this case, no in-house chemical neutralization processing is required.

Modutek designs and builds its own systems and equipment in-house. This means that the company can easily customize chemical collection carts to meet special customer requirements. Modutek works closely with customers to identify what they need and works and develops systems and equipment to meet their specific requirements. Contact Modutek for a free consultation and quote on equipment needed to support your chemical processing and disposal needs.

Improving Silicon Wafer Processing with High Temperature Quartz Tanks

Because silicon wafer processing uses acids and bases, the process requires tanks that are impervious to aggressive chemicals. Quartz tanks are stable and do not take part in wet process chemical reactions, even at the high temperatures reached during some of the process steps. Modutek’s quartz tanks use pure flame-polished quartz to reduce impurities that might contaminate the chemical reactions. To keep the temperature at the setpoint, Modutek has added precise temperature controls. As a result, Modutek’s quartz tanks represent an ideal way to implement wet process wafer fabrication steps.

Quartz Tanks Improve Output by Reducing Contamination

The output quality of wet process semiconductor manufacturing is directly affected by contamination during silicon wafer processing. When microscopic particles adhere to wafer surfaces, wafer etching can be disrupted and the semiconductors produced by the manufacturer can be defective or of poor quality. A major concern during silicon wafer processing is the reduction of the particle count on the surface of each wafer.

The high-purity semiconductor grade quartz used in Modutek’s tanks is made up of a crystal lattice containing tightly-held atoms of silicon and oxygen. These elements remain locked in the lattice while the wet process chemical reactions of wafer cleaning, stripping, and etching take place. This ensures that the quartz tanks act as neutral containers and don’t add contaminants or particles to the wafers.

After processing a wafer through one of the many steps of semiconductor manufacturing, a wafer has to be clean and almost completely free of particles. When Modutek’s quartz tanks are used for processing, potential particle contamination from the tanks is significantly reduced. The tanks are based on over 30+ years of bath design and feature a seamless, sloped flange construction. This is especially important for semiconductor manufacturing as industry trends have been moving toward tighter packing and reduced structure sizes. This means even a single small particle can block an etched path or result in a defective structure. By reducing particle counts, Modutek’s quartz tanks improve manufacturing results.

Quartz Tanks with Tight Temperature Control for Improved Etching Precision

The exact shape and location of etched structures in the silicon are critical for the correct functioning of the final semiconductor device. Etching speed determines the shapes of the etched structures in the silicon and the speed is controlled by the chemical concentration and the reaction temperature. The chemical concentration is set at the beginning of the process steps for most of the processes, but the temperature can be used to control the etching speed.

Modutek’s quartz tanks are designed to keep the temperature at exactly the setpoints required for the process and to deliver the anticipated etch speed. The bath temperature can be controlled precisely up to 180 degrees centigrade and the tanks feature a quick temperature rise of up to 2 degrees centigrade per minute with an accuracy of plus/minus 1-degree centigrade.

Heating is even and the fast rate of temperature increase improves throughput. The high accuracy allows precise prediction of etching distances and reliable repeatability of the process when different batches are manufactured. Tank design provides high reliability and safety with a view to a low total cost of ownership.

Using the Right Quartz Tanks Improves Processing and Overall Output Quality

As a leading semiconductor equipment manufacturer, Modutek works with customers to design processing equipment that will help them meet manufacturing requirements. Modutek’s recirculating and constant temperature quartz tanks improve silicon wafer processing by reducing contaminating particle counts and ensuring precise control of etching. The reduced particle counts and the reliable production of required etched shapes reduce defects and rejects in manufactured devices. Contact Modutek for a free consultation and quote on selecting the right equipment to support your manufacturing requirements.

How Megasonic Cleaning Improves Silicon Wafer Manufacturing

When silicon wafers are cleaned between manufacturing steps, it is critical to remove all contamination from the wafer surfaces. The remaining traces of process chemicals or microscopic particles can disrupt the etching process and result in defective or low-quality semiconductor devices.

Megasonic cleaning uses high-frequency sound waves in the cleaning tank to remove contaminants and particles from the silicon wafers. The technology can save time and money because it works quickly and does not require expensive chemicals. Silicon wafers cleaned with Megasonic cleaning are completely clean with a reduced particle count. As a result, the technology can improve the operation of semiconductor manufacturing lines for semiconductor fabricators and research labs.

Megasonic Cleaning Reduces the Use of Toxic Chemicals

The cleaning of silicon wafers after the completion of each semiconductor manufacturing step is accomplished by soaking the wafers in mixtures of chemicals including hydrochloric acid or sulfuric acid. In addition to the cost of the chemicals themselves, there are ongoing costs related to the storage, delivery, and disposal of these chemicals. The possibility of leaks and the disposal of the waste chemicals represent environmental hazards that are continuously being mitigated with tighter regulations. Reducing the use of aggressive chemicals can save money beyond their direct cost and can improve the environmental footprint of the semiconductor manufacturing facility.

With Megasonic cleaning, a frequency generator produces an electric signal in the MHz range that is transmitted to a transducer. The transducer that is immersed in the cleaning solution converts the signal to sound waves in the cleaning tank. The sound waves create microscopic cavitation bubbles that deliver a gentle scrubbing action against the surface of the silicon wafer. The cleaning intensity is strong enough to dislodge impurities and contaminants but will not damage the wafer surface or the microscopic structures that have been etched into it.

When Megasonic cleaning is used to replace some of the traditional cleaning steps, the use of chemicals is reduced. Megasonic cleaning uses plain water or water with the addition of mild detergents. The cost benefits and reduced environmental impact can be substantial, and the areas where Megasonic cleaning is used will have increased worker safety and reduced chemical exposure.

Megasonic Cleaning Can Deliver Improved Cleaning Performance

While acid baths work well for cleaning general contaminants from silicon wafer surfaces, ensuring low particle counts can be challenging. Contaminating particles can block etching and cause defects in the final semiconductor devices. As functions become more and more closely packed on the wafer and microscopic structures become smaller, a single particle can affect the etched shapes and current paths. A key factor for improving output quality and reducing defects is reducing particle counts to a minimum.

Microscopic particles can be difficult to remove from the surface of silicon wafers because they often develop a static charge that allows them to cling to the wafer. Chemicals can dissolve the substances that make the particle adhere to the wafer surface but the static charge often remains as an additional bond. With Megasonic cleaning, very small cavitation bubbles form and collapse in tune with the sound wave frequency in the MHz range. When a bubble collapses near the wafer surface, it emits a powerful jet that dislodges any particle still clinging to the surface. Wafers that have been cleaned with Megasonic cleaning systems have a lower particle count as well as a high degree of cleanliness.

Modutek Can Help with Megasonic Cleaning Integration

As a leading manufacturer of wet process semiconductor manufacturing equipment, Modutek can help customers integrate Megasonic cleaning into their wafer cleaning process. Modutek offers free consultation and can show customers how to realize the benefits of lower costs, better output quality, and improved yields.

How Specialized Equipment Improves Wafer Cleaning Results

When equipment is specially designed for a specific cleaning process, residue and particle removal from wafers can be improved. A better wafer cleaning process reduces semiconductor defects and can result in improved output quality. Specialized equipment can clean more quickly, allowing higher facility throughput. Specialized and customized equipment can be adapted for batch processing, continuous manufacturing or prototyping, improving production line performance, and reducing costs.

Specialized Equipment Delivers Specific Advantages

Modutek has developed specialized equipment that addresses issues with specific semiconductor manufacturing processes. Resulting advantages include better control of process variables, more efficient cleaning, reduced space requirements, and more flexible automation. While standard solutions are also available and are sometimes sufficient, the specialized equipment will deliver superior results in specific cases.

Piranha Etch Clean is often used for post-etch clean and for the removal of organic matter. Modutek has implemented a specialized control strategy that gives more reliable cleaning results while cutting chemical costs. The “bleed and feed” method provides tight control of temperature and chemical concentration to deliver superior cleaning performance.

A wafer cleaning process used in semiconductor manufacturing such as Piranha Clean has to take place in special tanks that are impervious to the process chemicals. Modutek’s heated quartz tanks minimize particle contamination while delivering precise temperature control. They are available in recirculating and constant temperature models are made from boron-free virgin fused quartz.

For many process steps, wafers must be carefully rinsed after cleaning. Modutek’s specialized quick dump rinsers minimize rinsing time while reducing the consumption of deionized water. Modutek’s specialized design has eliminated particle entrapment by reducing particle contamination at the rinsing stage.

After rinsing, wafers have to be dried while limiting additional particle contamination. Modutek offers IPA vapor drying stations but has developed a specialized single-chamber unit that rinses and dries the wafers without moving them to a new station. Moving the wafers exposes them to additional particle contamination and the single chamber IPA vapor dryer features extremely low particle counts.

As microscopic structures on silicon wafers become smaller and more tightly packed, a reduced particle count becomes critical for some wafer processes. Modutek’s use of Megasonic cleaning uses high-frequency sound waves in a cleaning solution to remove almost all remaining particles on wafer surfaces. The cavitation bubbles created by the sound waves can dislodge even the smallest particles, delivering an almost completely particle-free wafer.

Specialized Software Control for Automation

To control the wafer cleaning process, specialized software and automation can help deliver exactly the cleaning chemicals required while eliminating human error. Modutek uses its own SolidWorks Simulation Professional and Flow Simulation software and can adapt the programs to any process. Modutek’s wet bench stations are available in manual, semi-automatic, and fully automated versions with the automation designed to support the latest wet process technology. The specialized automation can be customized for specific applications to satisfy customer process requirements.

How Modutek’s Specialized Equipment Improves Performance

Specialized equipment can reduce particle counts, improve cleaning, reduce costs and increase production capacity. Modutek works closely with customers in a variety of industries and develops specialized wafer cleaning equipment to meet their unique needs. When additional customization is needed, Modutek can adapt equipment and software as required. Because the company designs and builds its products in-house, it can make the changes needed itself without relying on third parties.

With Modutek’s specialized equipment, customers ranging from large semiconductor manufacturers to small research labs can achieve excellent production results, especially after the additional customization that Modutek can provide. Superior wafer cleaning performance impacts all aspects of semiconductor manufacturing, from initial prototyping to full production line fabrication. Modutek can help with the choice of specialized equipment, suggest customizations, and ensure that the delivered equipment meets expectations.

Important Things to Know Before Buying a Wet Bench Station

There are a number of process and production requirements that need to be considered before buying a wet bench station. In addition to knowing which process chemicals are needed, you also need to decide on the degree of automation and whether any customization is needed for your station. If your application requires the use of aggressive chemicals, you also need to consider chemical delivery, handling, and disposal systems. Once silicon wafers have been cleaned or etched on the wet bench station, you have to know how the rinsing and drying process will be performed while keeping contamination to a minimum. The kind of semiconductor manufacturing you’ll be carrying out determines the type of wet bench station, and how you plan to run your facility impacts many of the other decisions you’ll have to make.

The Process Determines the Type of Station

Depending on the details of the semiconductor manufacturing process you’ll be using, you may be etching or cleaning wafers with acids and bases or you may be using solvents. Chemicals such as hydrochloric acid or hydrogen peroxide are extremely corrosive and require stations made of polypropylene and tanks made of inert materials such as quartz. Stations that use solvents such as acetone or IPA are made from stainless steel and the chemicals are not as aggressive.

Chemical Handling Systems Increase Safety

When you install chemical handling systems with your wet benches, you avoid spills and eliminate human error in dosages and mixing. Chemical handling includes delivery to the process, neutralization of the chemicals after use, and safe disposal of the waste. Chemical handling systems come in many sizes and can handle a variety of tasks. An experienced manufacturer of wet process equipment can advise you regarding the best systems for your application.

Automation Can Help Improve Performance

Wet process automation can range from stations that perform a few tasks independently to fully automated stations that run the whole process by themselves. For large production runs, full automation can save time and ensure consistency. For batch processing or the development of prototypes, semi-automated stations run standardized tasks while operators take over manual control where needed. You have to decide how you are going to run your facility and whether a high degree of automation is appropriate.

Specialized Sub-Systems Can Meet Your Unique Process Needs

The complexity of semiconductor manufacturing means that each facility has unique features and special requirements. Often specialized subsystems can improve facility performance. For example, a quick dump rinser speeds up rinsing while a unit that combines rinsing and IPA vapor drying can reduce particle contamination. If particle count reduction is critical for your process, Megasonic cleaning using high-frequency sound waves can reduce particle counts to a minimum. Look at specialized sub-systems to see if you can use any of them for your process.

Customization Can Help You Get Exactly What You Need

When standard wet benches don’t quite do what you want, it’s time to work with a wet bench manufacturer that designs and builds their own equipment. When design and assembly are carried out in-house, the manufacturer has the capability to adapt standard equipment to exactly meet your requirements. It could be something simple such as a custom tank size and shape or more complex features such as special automation programming for extra process steps. Experienced manufacturers can customize your equipment and can advise you on what equipment is best suited for your application before building it to your requirements.

Modutek Has the In House Expertise and Experience

Modutek has been designing and building wet bench stations and equipment for over 40 years and can advise customers to make sure they get the equipment they need. As one of the leading semiconductor equipment manufacturers, Modutek’s in-house expertise allows them to develop the specialized sub-systems needed by customers. When considering the purchase of a wet bench station, Modutek can help you choose the equipment and make sure it operates the way you want.

How Stainless-Steel Stations Provide Safe Solvent Processing

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.

How Teflon Tanks Improve the KOH Etching Process

How Teflon Tanks Improve the KOH Ethcing ProcessEtching silicon wafers with potassium hydroxide (KOH) is a popular process for semiconductor manufacturing because it is relatively safe compared to other etching methods and because it features good control of the etch rate. When carried out in Teflon tanks, contamination is reduced and the etch rate can be controlled.

A key factor for successful etching is to determine the required etch rate. If the rate is too fast, the KOH may etch too far into the silicon, while if the rate is too slow, the etched holes might be too shallow. Improving the KOH etching process means applying several control methods to the etch rate to ensure the resulting etched shapes are exactly correct.

Process Factors that Affect the KOH Etch Rate

The KOH etch rate in silicon wafers is influenced by the following factors:

  • Process temperature. The higher the temperature of the KOH solution, the faster KOH will etch the silicon.
  • Solution concentration. A higher concentration increases the etch rate. Normally the concentration of the KOH solution is about 30 percent, but it can vary from 10 to 50 percent, with a corresponding effect on the etch rate.
  • Doping. Doping means adding impurities to the silicon crystal. When boron is placed into the silicon crystal lattice at a specific location, etching stops in that direction. Boron doping can influence the shapes to be etched in this way.
  • Crystal lattice orientation. The silicon crystal atoms are arranged in a cubic lattice that has a greater atom density in some directions than in others. Etching is slower in directions with a higher atom density.

All four factors have to be taken into account when designing the mask to obtain the microscopic structures in the silicon. The silicon wafer has to be oriented correctly to give the different etch rates along with the different lattice directions. Doping has to be in a place where etching is required to stop and the correct KOH solution concentration has to be mixed. These are initial conditions that are established before the process starts. A target temperature can be set as well but the temperature can be varied to adjust the etch rate during processing. The ability to vary the etch rate by changing the temperature results in excellent control of the KOH etching process.

Modutek Teflon Tanks Feature Rapid Heating and Precise Temperature Control

Modutek’s Teflon tanks for KOH processing are available in a circulating or a static design. The heat source is either inline or immersed in the overflow weir. An all-Teflon liquid path reduces the possibility of contamination. The heated tanks can improve the KOH etching process with short heat-up times and precise temperature control. As a result, Modutek Teflon tanks can keep the etch rate steady by maintaining an accurate temperature set point or can allow the etch rate to be adjusted with fast and reliable controlled temperature changes.

Both models of Teflon tanks feature uniform heating throughout the baths, level and temperature limit settings, and a drain interlock. Heat up rates are 2 to 3 degrees centigrade per minute and the temperature is controlled with a precision of plus/minus 0.5 degrees centigrade. The operating temperature is from 30 to 100 degrees centigrade and a cooling refluxor with Teflon cooling coils is included.

Modutek’s Teflon tanks are available in standard sizes but can work with customers to design and build systems with custom sizes and special requirements. With their high-quality materials, precise temperature controls, and customization capabilities, Modutek’s Teflon tanks can improve the KOH etching process to deliver better semiconductor manufacturing results. Contact Modutek for a free consultation to discuss your specific process requirements.

How On-Site Acid Neutralization Systems Provide Safe Chemical Disposal

When the right acid neutralization system is chosen, it can automatically add the required neutralizing chemicals to acid waste left over after a semiconductor manufacturing process step. Ideally such a system should use the least amount of chemicals while ensuring adequate neutralization of waste to comply with environmental standards. The system has to have enough capacity to handle the waste chemical flow and it must operate reliably, protecting against spills and documenting chemical use and discharge. With overall environmental standards tightening and local regulations becoming more stringent, semiconductor manufacturers need acid neutralization systems that provide safe and reliable disposal of chemical waste.

How to Choose Continuous Flow or Batch Acid Neutralization Systems

Acid neutralization systems can operate on a continuous basis or can neutralize individual batches of waste chemicals. For mass production of semiconductor parts, fabrication lines operate over extended periods, using fixed amounts of chemicals and producing uniform quantities of waste.

For these large-scale operations, a continuous flow acid neutralization system is the best choice. Because the nature of the waste chemicals is known and remains consistent over time, the neutralization process can add fixed amounts of low-pH chemicals to continuously neutralize the waste flow. Neutralization can be fine-tuned because the overall process doesn’t change.

Batch neutralization systems are better suited for the production of small quantities of semiconductor products. Typical applications are prototype production, production of small quantities for testing or the manufacture of special components. For these operations, the waste chemicals have to be neutralized in small volumes and each process is different. The batch acid neutralization system has to measure the pH of the waste chemicals, and determine what low-pH additions are appropriate. The neutralization is different for each batch as is each outflow.

Automation Can Play a Key Role in Effective Acid Neutralization Systems

Automated acid neutralization systems can help reduce chemical use, ensure regulatory compliance and reduce spills. The system automatically adds the required chemicals to the waste solution, tracks chemical use, measures outflow pH and records the results. Workplace safety is increased and human error is reduced. The records of chemical use and outflow pH can demonstrate that environmental standards are met.

Automating continuous flow systems is comparatively easy because the process parameters are known and they don’t change. The complete automation of batch neutralization systems can be challenging because key variables as well as the chemicals involved can vary from batch to batch.

For a continuous flow chemical acid neutralization system, the acid to be neutralized and the low-pH chemical to be used are known. The automation only has to add the required amount of neutralizing chemical on a continuous basis and record the resultant pH. For slight variations, a control loop can adjust the amount of neutralizing chemical to achieve the required output pH.

A fully automated batch neutralization system first has to measure the batch pH and add an amount of low-pH neutralizer. Depending on the chemicals involved, the automated system may have to add different neutralizing chemicals in several stages to achieve the required output. The automated system is complicated to program and difficult to set up. For batch neutralization systems, operator involvement to select the type of neutralization required can simplify the operation of the automated system and make it more effective.

Modutek Can Help Select the Right Acid Neutralization System

Modutek has a full line of chemical handling equipment, including acid neutralization systems. The company works closely with customers to determine their needs and can customize systems to meet special requirements. Once delivered, Modutek makes sure that the acid neutralization systems operate as specified and customers are completely satisfied. Contact Modutek for a free consultation to discuss the chemical disposal requirements needed at your facility.