Choosing an Acid Neutralization System to Safely Handle Chemical Disposal

Choosing an Acid Neutralization System to Safely Handle Chemical DisposalWet process semiconductor manufacturing lines use aggressive chemicals to clean and etch silicon wafers. When a cleaning or etching step is complete, the remaining chemicals have to be disposed of safely. Low pH acids such as hydrochloric acid have to be neutralized with high pH chemicals so that the pH of the mixture approaches the neutral value of seven. The acid neutralization can be carried out continuously or in batches and either process can be fully automated. Ideally an acid neutralization system acts reliably with a minimum of supervision and keeps records of chemical use and discharge to demonstrate compliance with environmental regulations.

Continuous Flow and Batch Neutralization Systems Fulfill Different Requirements

The choice of an acid neutralization system reflects the type of semiconductor manufacturing that takes place. Large scale continuous manufacturing lines produce a continuous flow of waste chemicals. The composition of the flow and its volume changes little and can be analyzed in detail. A continuous flow acid neutralization system can then be designed to automatically and reliably neutralize the out flow. Because small changes can easily be detected and the dosages of neutralizing chemicals can be automatically adjusted, the automation required for such a system is easily set up. The automated continuous flow acid neutralization system can keep records of its neutralization activity and the volume and pH of the waste flow.

The neutralization of waste chemicals used in batch manufacturing is usually more complicated. Batch manufacturing is used for prototypes, one-of-a-king components and small quantities of special parts. Each batch can be different and it makes sense to use a batch acid neutralization system for these processes.

Instead of adjusting chemical dosages of an established process as in the continuous flow systems, batch neutralization systems have to measure the pH of the waste chemicals and add specific neutralizers. Several stages of neutralization may be required before the discharge is acceptable. Once the neutralization process is finalized, the sequence can be fully automated and can run as the batch is processed.

Other Considerations When Choosing an Acid Neutralization System

Once the choice of continuous flow or batch system is made, the acid neutralization system has to fulfill a few basic requirements. The system capacity has to be sufficient for the proposed application, with capacities ranging from a few gallons to hundreds of gallons per minute. The system can be located indoors if there is space but it can also be designed for outdoor operation. If automated, the exact automatic functions have to be programmed and set up. Finally the monitoring and record-keeping functions have to be determined.

Operational characteristics have to be considered as well. If the system is fully automated, it may run without supervision but alarms will be required for situations such as low chemical supply or a pH level outside permissible limits. Recording of neutralization process parameters can be digital, with a log, or on a chart recorder. Containment of spills is important and depends on whether the installation is indoors or outdoors. Spill detection has to be incorporated into the alarm system and the whole operation has to comply with environmental regulations.

Modutek Can Supply Acid Neutralization Systems to Meet Customer Needs

Included in Modutek’s complete line of wet process equipment are compact acid neutralization systems that can be customized to meet specific needs. Systems can be designed to fit into the space available at a customer’s facility and Modutek can help select suitable automation and operating characteristics. The Modutek acid neutralization systems operate reliably to keep waste discharge parameters close to specified values and a digital chart recorder documents compliance with discharge regulations.

5 Important Things to Know Before Buying a Wet Bench Station

5 Important Things to Know Before Buying a Wet Bench StationWet bench semiconductor manufacturing has many variations and applications often have unique features. Before buying a wet bench station, there are several main things to look at before deciding what equipment is best suited for a specific manufacturing task. Options include the type of station, how it operates, how it receives its chemicals and what specialized or custom features are required. When a prospective supplier has extensive experience and the required expertise as well as offering a complete line of wet bench equipment and customization as required, the selection becomes easier. Five main things influence which of the available wet benches to buy. Knowing these five things helps determine which station satisfies the manufacturing application requirements.

1. Different Types of Wet Process Stations Have Different Advantages

Types of wet benches include a standard white polypropylene construction for acid and base process applications such as KOH and RCA clean. Solvent application wet benches for processes such as acetone, IPA and photo resist stripping have a stainless steel construction. Stations are available with a dry-to-dry process and can include a chemical fume hood. An experienced supplier can advise on the different options and the customization possibilities.

2. The Degree of Automation Depends on the Application

Manual stations are best suited for initial development work when the main process parameters are not yet known. Manual stations can be used to develop a process framework. Once the overall process is set, semi-automatic stations can be used to program the fixed parameters to run automatically while operators retain manual control of some variables for optimization purposes. Once the process is fully developed, fully automated stations can be used to run the productions line and increase throughput.

3. Chemical Delivery Systems Improve Process Control

Chemical delivery systems run and monitor chemical storage, delivery to the process and disposal of chemical discharge. They minimize waste and reduce spills. Chemical delivery systems are recommended for applications that rely on highly accurate dosages of specific chemicals during the manufacturing process.

4. Rinsing and Drying are Critical for Avoiding Particle Contamination

Reduced particle counts on wafers improve process yields because particles can cause product defects. Special configurations such as the combined rinsing and drying station and the quick dump rinser improve process efficiency and reduce the particle count. Depending on the wet process application, such rinsing and drying configurations may improve overall facility performance.

5. Special Custom Functionality Can Be Built Into Standard Stations

Semiconductor equipment manufacturers that build their own wet process stations in house can add custom functionality when an application requires it. For example, an application may include etching of aluminum layers on a wafer and a special vacuum metal etcher may have to be incorporated in the wet bench process. Some applications require an especially low particle count and wafers may have to be cleaned with Megasonic equipment to dislodge and remove the tiniest particles. Such specialized custom functions work best when a custom design integrates them into the rest of the wet bench process.

Once customers are aware of these five pieces of information, they can proceed to select a supplier that can satisfy them on all five points. They will then be able to specify the kind of performance they want to achieve and help make sure that they get the equipment they need.

Modutek Builds Their Own Equipment to the Highest Standards

Modutek design and build their own equipment in house and can customize wet process stations as required. Their specialized modules include the combined rinsing and drying IPA dryer, the quick dump rinser and the Megasonic cleaner. The company can help customers with all five of the listed points and ensure the purchased wet benches meet their needs.

Improving Wafer Manufacturing Processes with Automated Equipment

Improving Wafer Manufacturing Processes with Automated EquipmentAutomated wafer fabrication equipment can improve semiconductor manufacturing facility performance, but all the associated process settings must be programmed properly. Before the manufacturing process can be implemented on a fully automated wet bench station, the settings, timing and other parameters have to be fine tuned. As circuit geometries and micro-structures become smaller and more tightly packed, the chemical concentrations, temperature levels and timed intervals affecting the etch rate become more and more critical. Fully automated equipment can precisely and reliably run a semiconductor manufacturing process once the correct variables are determined and programmed.

Manual Operation Can Determine the Settings for the Process Variables

Once wafer fabrication processes such as KOH etching are chosen, the process variables can be selected. Etching can be either isotropic or anisotropic and etching speed or precision can vary. Other factors may come into play as well. Initially it makes sense to run the new process on a manual station so that the process results for rough settings of basic variables such a concentrations, temperature and timing can be determined. These variables can then be adjusted to get an initial and acceptable process result.

Semi-Automatic Operation Can Fine Tune the Process

After determining the rough settings of the basic variables in manual operation, transferring to semi-automatic operation to optimize the process steps can save time. Those variables that will no longer change can be programmed into the semi-automatic software control while the others can be adjusted manually to get the best process result. In this way, as each process step is optimized, it can be programmed so that when optimization is complete, the process is ready to run on fully automated wafer processing equipment.

Fully Automated Operation Improves Semiconductor Manufacturing Facility Performance

Fully automated wet process stations for which the process has been optimized in manual and semi-automated operation can help improve overall production facility performance in the following ways:

  • Programmed settings ensure that the process is repeatable for different batches
  • Use of wet processing simulation software during optimization helps ensure accurate process parameters
  • Full automation eliminates human error
  • Precise dosages of chemicals and accurate timing results in fewer defective products
  • Throughput and wafer yields are increased

The programmed settings can be used again to get an identical result and they can be used for similar applications with minor adjustments. Instead of relying on operators to prepare etching baths, the fully automated station mixes the required chemicals quickly, safely and reliably, always the same way and without waste or spillage. The result is precise control over the process steps, fast execution without delays and high output quality.

Improved Output Relies on Optimized Software and Fully Automated Stations

Using an optimization strategy with manual and semi-automatic operation and running the optimized process on fully automated wafer fabrication equipment can lead to continuous improvement in semiconductor manufacturing operations. As new processes are brought online and optimized, they replace older versions that may not use chemicals as efficiently, may rely on some manual input or may not have the same precise and reliable execution as the fully automated stations. Tailor-made software working with fully automated wet process equipment can result in such continuous improvements.

With 40 years of experience in wet process technology and extensive in house expertise from manufacturing its own equipment, Modutek is ideally situated to supply fully automated equipment that improves semiconductor manufacturing output. The company has a complete line of standard and custom-built wet process equipment and the SolidWorks software used to calculate process parameters is programmed in house. Working closely with its customers, Modutek designs and builds its fully automated stations and programs the corresponding software to help them meet their goals for continuous improvement. Contact Modutek for a free quote or consultation on selecting equipment that supports your specific manufacturing process requirements.

How Specialized Wet Bench Equipment Improves the RCA Clean Process

How Specialized Wet Bench Equipment Improves the RCA Clean ProcessThe RCA clean process removes contaminants from the surface of silicon wafers so that additional wet process semiconductor manufacturing steps can take place. The process consists of two steps, with the SC1 step removing organic compounds and the SC2 step dislodging any remaining metallic residues or particles. Specialized wet benches ensure that contaminant and particle removal is as complete as possible and the silicon wafers remain clean. To accomplish this, the equipment carefully rinses away contaminants and minimizes the handling of the wafers. Automation can be used to replicate process parameters reliably and consistently. Modutek can supply both standard and customized specialized equipment to carry out the RCA clean process.

RCA Clean SC1 Removes Most of the Wafer Surface Contamination

The SC1 cleaning step uses chemicals to dissolve impurities while leaving the underlying silicon surface unaffected. The wafers are placed in a solution containing equal parts of NH4OH (ammonium hydroxide) and H2O2 (hydrogen peroxide) in five parts of de-ionized water. The solution is heated to about 75 degrees centigrade and the wafers are left in the solution for ten to fifteen minutes. Organic residues are dissolved and particles are removed. A thin layer of silicon oxide forms on the wafer and there is some contamination with metallic ions and particles.

RCA Clean SC2 Removes Metallic Impurities

For SC2, the newly cleaned wafers are placed in a bath containing equal parts of hydrochloric acid and hydrogen peroxide in five parts of de-ionized water. The exact ratio may vary depending on the application. The bath is heated to about 75 degrees centigrade with the wafers soaking for about ten minutes. The solution specifically eliminates alkali residues, metal hydroxides and other metallic particles. The wafers are now completely clean and free of all types of particles.

Wafer Cleaning Equipment Has to Fulfill Specialized Functions

Specialized equipment is needed to carry out RCA clean process steps effectively. The required chemicals have to be delivered in the right quantities to the cleaning baths and then, when the chemicals are no longer needed, they have to be neutralized and disposed of safely. The concentration of the chemicals, the bath temperature and the timing are all important for being able to subsequently reproduce the desired cleaning performance. Contaminants and particles have to be rinsed away and filtered out. Key features of effective cleaning are a low particle count on the wafer surface and a resulting low rejection rate for fabricated wafers.

Modutek’s Wet Process Equipment Provides Specialized Features

Modutek’s wet benches and chemical stations support both of the RCA cleaning steps. Chemical delivery systems ensure that the right amounts of chemicals are supplied to the process safely and that waste chemicals are neutralized before disposal. The FM4910 material of construction keeps particle contamination low and is safe to use with the acid and base processes of RCA clean. All baths include a continuous flow de-ionized water chamber with chemical circulation and filtration to rinse away and remove contaminants. The SolidWorks flow simulation software lets operators calibrate dosages precisely and store settings for future use.

As well as fulfilling customer needs from its extensive line of wet process equipment, Modutek can build custom systems for specific applications. Customers who wish to incorporate drying, etching or stripping functions as well as RCA clean in their process lines can rely on Modutek to design and build exactly what they need.

With 40 years of experience in the wet process and technology sector and one of the leading semiconductor equipment manufacturers, Modutek has the expertise in house to provide specialized equipment for the RCA clean process and other semiconductor manufacturing applications. Customers can count on Modutek to help them find effective solutions and supply the corresponding equipment. Contact Modutek for a free quote or consultation to discuss your process equipment requirements.

How Are Isotropic and Anisotropic Processes Used to Improve Silicon Wet Etching?

How Are Isotropic and Anisotropic Processes Used to Improve Silicon Wet EtchingThe microscopic structures produced by silicon wet etching can be created with a high degree of precision by using both isotropic and anisotropic processes. Isotropic etching is faster but may etch under masks to create rounded shapes. Anisotropic etching can be controlled more precisely and can produce straight sides with exact dimensions. In each case, controlling the etch bath temperature and the etchant concentration is critical for successful micro-structure creation and for repeatability for subsequent batches.

How Isotropic and Anisotropic Etching Differ

Silicon wafers have a mono-crystalline lattice structure that repeats in all directions but is not equally dense in all directions. Vertical planes contain a different number of silicon atoms than diagonal planes. This means that etching with certain etchants is slower in the directions with more atoms while it progresses faster in the directions with fewer atoms.

Etchants used for isotropic etching, such as hydrofluoric acid, etch at the same speed in all directions, independently of silicon atom density. For etchants used for anisotropic etching, such as potassium hydroxide (KOH), the etching speed depends on the number of silicon atoms in a crystal lattice plane and therefore depends on the direction of the different planes.

The difference in anisotropic etching speeds allows a better control of shapes etched into the silicon wafers. With a corresponding orientation of the silicon wafer, etching can be timed to produce straight or angled sides and sharp corners. Etching under masks can be reduced.

How Isotropic and Anisotropic Etching Are Used in Semiconductor Manufacturing

Isotropic etching is harder to control than anisotropic etching but it is faster. In the initial stages of silicon wafer fabrication, large features are etched into the silicon. At this stage of manufacturing, etching speed is important for facility throughput. Isotropic etching is used to quickly create these large shapes with rounded sides and corners. Although process engineers and operators have less control over the shape of the feature being etched, accurate temperature and concentration control are still important to ensure that the rounded shapes being created are the same on wafers processed in different batches.

After the large shapes are etched with an isotropic process, the micro-structures and metal paths require better control of the details. Anisotropic etching provides this control as long as the lattice structure of the silicon wafer is oriented correctly. Anisotropic KOH etching is reliable and easily controlled. It can be used to create the precise, straight-sided shapes that are required in the final semiconductor product. Accurate control of the temperature and etchant concentration is even more important for anisotropic etching because these process parameters strongly influence the etching speeds in the various directions and therefore influence the final shapes that are etched.

Modutek Teflon Tanks Support Both Isotropic and Anisotropic Etching

For silicon wet etching processes in which the etch speed is temperature dependent, Modutek’s heated Teflon tanks provide rapid heating and tight temperature control. The tanks are either recirculating or static and they can be built into any new wet bench configuration. The tanks feature 360-degree overflow filtration and uniform heating throughout the bath. The heat-up rate is 2 to 3 degrees centigrade per minute and the temperature control accuracy is plus/minus 0.5 degree centigrade. The temperature controls of these tanks are ideally suited for both isotropic and anisotropic etching.

In terms of control of etchant concentration, Modutek can provide for the injection of de-ionized water into the tanks. Because etchant concentration affects the etch speed, accurate concentration control is important for final product quality and repeatability. Modutek can analyze customer requirements, find and build custom solutions and ensure that process control is precise enough to deliver the required results, both for isotropic and for anisotropic etching.

How Megasonic Cleaning Reduces Costs and Improves Silicon Wafer Yields

How Megasonic Cleaning Reduces Costs and Improves Silicon Wafer YieldsBetween process steps that etch silicon wafers and deposit circuit paths, semiconductor manufacturing relies on wafer cleaning to remove material from previous process steps and microscopic contaminating particles. As structures and circuits on wafers decrease in size, even the tiniest particles can interfere with etching and the creation of circuits and micro-structures.

Such interference can cause defects in the final semiconductor product, lower product performance or cause a reduced product lifespan. The use of Megasonic Cleaning results in a gentle cleaning action that dislodges particles from wafer surfaces while leaving the wafer, its circuits and structures undamaged. Megasonic Cleaning reduces chemical use and final product rejection rates using a process that is completely safe and environmentally friendly.

Megasonic Cleaning Delivers Quick Results with Safe, Gentle Cleaning Action

Megasonic cleaning systems generate microscopic cavitation bubbles in the cleaning solution. When a bubble bursts, it produces a tiny jet that dislodges contaminants from the surfaces of the parts to be cleaned. Lower ultrasonic frequencies generate comparatively large bubbles and powerful jets while high frequencies clean with smaller bubbles and less energetic jets.

The tiny structures etched into the silicon and the microscopic metal filaments deposited on the wafers are easily damaged. Products such as microprocessors, micro electro mechanical systems (MEMS), and controllers may not work properly if precise cleaning procedures are not followed. Using frequencies above 950 kHz in the megahertz range for cleaning the wafers ensures that the Megasonic Cleaning action takes place with the tiniest bubbles and the least energetic jets. As a result, Megasonic Cleaning is gentle enough to remove contaminating particles while leaving silicon surfaces, micro-structures and metallic deposits intact.

Reduced Use of Chemicals Saves Money

The traditional wafer cleaning process uses strong chemicals to strip contaminants and particles from wafer surfaces. In addition to the cost of purchasing the chemicals, there are costs for storage, handling and disposal. As environmental regulations become more strict, hazardous chemicals have to be stored in special containment facilities. Chemical delivery systems have to include special measures that guard against spills. Once the chemicals are used, they have to be neutralized and disposed of in a way that doesn’t harm the environment. All these measures are expensive and will become more costly as regulations tighten.

Workplace safety is another costly aspect of the use of hazardous chemicals. Operators have to be protected against inadvertent contact with corrosive materials and many of the chemicals emit dangerous vapors that require expensive ventilation equipment. Operators that work with hazardous chemicals need protective clothing that reduces productivity and work accidents can lead to serious injury.

Megasonic Cleaning removes contaminants from wafers and dislodges particles more effectively than chemical methods. The reduced use of chemicals saves money and leads to a safer, more productive workplace environment.

Modutek’s Megasonic Cleaning Improves Sub-Micron Particle Removal

Modutek has partnered with Kaijo Corporation, a world leader in megasonic and ultrasonic cleaning technology, bringing Megasonic Cleaning to wet bench semiconductor manufacturing. Modutek has integrated Megasonic Cleaners into the company’s wet bench equipment to produce unparalleled low particle counts. The bubbles of the Megasonic Cleaning system agitate the cleaning bath to disrupt boundary layers, allowing effective cleaning action around complex microscopic structures and inside holes. The tiny jets produced by the bursting bubbles break the bonds between the wafer surfaces and surface particles and allow the particles to be removed by cleaning solution currents.

The low particle counts achieved by Modutek’s wet bench stations incorporating Megasonic Cleaning reduce defects and improve yields for semiconductor manufacturing lines. Product quality rises while costs go down. Using the latest Modutek Megasonic Cleaning equipment improves overall facility performance for semiconductor manufacturing plants and research labs. Contact Modutek for a free consultation on selecting the right equipment to meet your manufacturing requirements.

How Process Controls Improve Silicon Nitride Wet Etching Results

 How Process Controls Improve Silicon Nitride Wet Etching ResultsThe silicon nitride wet etching process uses a phosphoric acid solution in water to etch mask material quickly and reliably but the process is hard to control. Etching speed depends on the concentration of the solution and the bath temperature. Adding water to the solution to control the concentration is dangerous and, at the same time, it can change the temperature. Controlling such an unstable solution with two interdependent variables is difficult, but in the absence of reliable controls, the etching rate is not accurately maintained and the removal of silicon nitride is not precise.

How Silicon Nitride Etching With Phosphoric Acid Works

In the silicon nitride wet etching process, the silicon wafer is masked with a silicon nitride coating that has to be selectively etched. A solution of about 85 percent phosphoric acid and 15 percent de-ionized water is used to etch the silicon nitride at an optimized temperature of 165 degrees centigrade. To speed up etching, the phosphoric acid solution is heated to its boiling point. As the solution boils, water from the solution is lost as steam and the concentration of the solution rises. The boiling point of the solution rises as the concentration rises and the etch rate increases as both the temperature and the concentration increase.

To correct the etch rate, water has to be added to the bath to bring the concentration and the temperature back down. Adding water to boiling phosphoric acid is dangerous because it can reduce the temperature of the solution to below boiling. When the phosphoric acid solution is no longer boiling, the added water can form a thin film on top of the acid instead of mixing in continuously. Eventually the film will mix with the acid all at once and a “bump” can result from the exothermic reaction.

To make sure small amounts of water mix into the solution continuously, the solution has to be kept at its boiling point. Because the boiling point is variable, standard controls with a fixed temperature set point don’t work. Modutek has developed an innovative silicon nitride wet etching process control solution that features precise control of the temperature, concentration and etch rate while ensuring safe operation.

The Modutek Control Strategy Improves Etching Results

Modutek’s control concept uses an always-on heater to keep the 85 percent phosphoric acid solution at its boiling point. As water is lost to steam, the concentration of the solution starts to increase and the temperature starts to rise above the original value. A thermocouple senses the temperature rise and signals the system to add water. A small amount of water is added and is immediately mixed into the solution by the boiling action. The concentration is maintained at the original 85 percent phosphoric acid and 15 percent water and the temperature stays at the boiling point of 165 degrees centigrade with this concentration. The etch rate remains constant and the operation is safe.

Because the safety of the Modutek control strategy relies on the constant boiling of the phosphoric acid solution, an additional thermocouple is located above the hot acid to sense the presence of hot steam. Another thermocouple senses the temperature of the acid. If no steam is present or if the acid becomes too hot, the process is shut down. These emergency shut-downs don’t take effect during normal operation, but are an additional safety feature in case of equipment malfunction or operator error.

Modutek’s Control Strategy Delivers Improved Etching Performance

Modutek has tested and fine tuned their control strategy with their Nb Series silicon nitride wet etching baths for customers using manual, semi automated and fully automated wet bench stations. Customers that have been using the new equipment have achieved an average etch rate of 65 angstroms per minute while limiting oxide etch as the controls ensure safe operation at a consistent and optimum operating point.

A reliably-controlled and constant etch rate yields predictable etching and silicon nitride removal within product tolerances. When etching is not the same from batch to batch, product quality suffers and product lifespan can be reduced. Modutek manufactures a complete range of silicon wet etching equipment and with the company’s innovative control system, rejection rates are reduced and facility output is improved.

 

How Wet Bench Stations Are Designed for Ergonomics and Safety

How Wet Bench Stations Are Designed for Ergonomics and SafetyTo etch and clean silicon wafers, wet bench stations use aggressive and toxic chemicals that have to be handled carefully. Ergonomic design ensures that employees don’t have to perform risky or strenuous maneuvers in normal operation of the facility. To load trays, control processes and dispose of waste, employees should not have to lift especially heavy weights, stretch to the limits of their reach or perform repeated strenuous actions. The Semiconductor Equipment and Materials International (SEMI) S8-0712 – Safety Guidelines for Ergonomics Engineering of Semiconductor Manufacturing Equipment can help manufacturers design equipment for comfortable and safe operation.

Key safety aspects of semiconductor equipment manufacturing include safe chemical handling and fire prevention. The FM 4910 specification and the Cleanroom Materials Flammability Test Protocol help manufacturers avoid using flammable materials in their equipment. Wet bench stations that adhere to these guidelines provide a better and safer working environment.

How Modutek Design Wet Bench Stations for Ergonomic and Safe Operation

Modutek designs its wet bench chemical stations according to the SEMI S8 guidelines and minimizes the use of flammable materials in its designs. Examples of safe and ergonomic

design measures applied by Modutek include the following:

  • Wafer holding trays are easy to load
  • Operator interface is on a swing arm
  • All stations are built around your ergonomic requirements

Ergonomic and safe design means that operators must be able to load equipment without strain. The wafer holding trays on Modutek’s wet benches can move to the front on robot arms that position the trays for optimal loading and unloading. Operators don’t have to stretch and can perform this often repeated action with a minimum of effort.

Operators have to be able to see the operator interface while monitoring the process. The interface monitor is usually off to the side of the wet bench station. The interface monitor is mounted on a swing arm that allows operators to adjust the position where they can view it while monitoring the process. The interface mounting arm can rotate and tilt to an ideal position and then can be locked with one hand. The operator can continue working while adjusting the interface monitor and doesn’t have to assume any unnatural positions.

All of Modutek’s wet bench stations are built and designed around your ergonomic and process requirements. Modutek does not sell stations which customers order from a catalog. Wet bench stations are built based on a customer’s specifications and incorporate features for ergonomic safety and repeatability. Besides ease of use Modutek also designs each station around your facility requirements. When the station is delivered all facility connections are pre-approved so your system will be up and running in a very short time. All of these added features save customers time and money.

In addition to these specific examples, Modutek applies ergonomic design principles and safety features across its full product line of wet process equipment. All its wet bench chemical stations satisfy safety regulations and are designed to keep employee physical effort to a minimum.

Equipment That Meets Ergonomic and Safety Guidelines

Modutek’s extensive line of wet process equipment and wet bench chemical stations are all designed according to the latest applicable ergonomic and safety guidelines. When customers need special equipment, Modutek can design customized systems to satisfy specific requirements. In that case, ergonomic and safety features are customized as well to make sure the special equipment meets or exceeds the guidelines.

Older equipment is often not compliant with new regulations. When that is the case, it’s a good time to purchase new or upgraded equipment. Whether new or an upgrade, the equipment comes with improved ergonomics and safety features. When employees work with reduced physical stress and feel safe in the workplace, employee morale and job satisfaction increases. If you need help selecting a wet bench station for your process requirements and also all ergonomic and safety regulations, contact Modutek for a free quote or consultation at 866-803-1533 or email [email protected].

Improving Piranha Etch Process Results in Silicon Wafer Cleaning

Improving Piranha Etch Process Results in Silicon Wafer CleaningPiranha etch is a popular process for silicon wafer cleaning, but it has to be tightly controlled to be effective. The mixture of about one part hydrogen peroxide and three parts sulfuric acid rapidly removes organic matter from silicon wafers. The etch process takes place in heated quartz tanks where both temperature and chemical concentration affect the etch rate.

Precise control is difficult because mixing the original solution is exothermic, and the hot mixture is then maintained at between 130 and 180 degrees centigrade. The hydrogen peroxide decays to form water, diluting the mixture. The rate of decay depends on the temperature, but adding extra hydrogen peroxide to keep the concentration steady increases the temperature.

With several key variables interdependent, accurate control with traditional control systems is not easy and results can be varied. The mixture, with periodic addition or spiking with hydrogen peroxide, has a useful life of only about one day. Modutek has developed a control strategy that improves process results while reducing chemical use.

The Modutek “Bleed and Feed” Process Control Strategy Delivers Improved Results

Modutek’s “Bleed and Feed” process control strategy keeps the concentration of the Piranha mixture at the desired level while increasing the lifespan of the mixture. The company uses a two-tank “clean” and “dirty” tank design. When the concentration of hydrogen peroxide in the dirty tank goes down, a small amount of mixture is drained from the tank and is replaced by an equal amount from the clean tank. The clean tank then receives a fresh amount of mixture. The clean tank and dirty tank mixtures and the amounts of the bleed and the feed are all programmable so that the desired concentrations can be maintained for an extended period. Using the “Bleed and Feed” method, the Piranha mixture has a much longer life span.

“Bleed and Feed” Control Strategy Advantages

The control strategy of frequently adding small amounts of a programmable hydrogen peroxide/sulfuric acid mixture to the main “dirty” tank mixture to maintain its concentration provides several advantages to the silicon wafer cleaning process. Instead of spiking the mixture with hydrogen peroxide, the Modutek method adds an already mixed dosage to the main mixture, reducing temperature instability and allowing better control of the process. When the main mixture is relatively stable, it lasts longer and doesn’t have to be replaced as often. The temperatures and concentrations are more stable and the control of the etch or strip rate is more precise.

The Modutek “Bleed and Feed” Process Control Delivers Substantial Benefits

With more precise control of the process and a more stable Piranha mixture, Modutek’s “Bleed and Feed” process control improves Piranha etching results. Specific benefits include the following:

• Better control of the process increases reliability of strip results

• Precise temperature and concentration levels result in a constant strip rate

• Programmable dosage levels add control flexibility for predictable results

• Reproducing process parameters creates excellent repeatability

• Longer mixture life reduces chemical use

• Replacing the mixture less often reduces down time

• Chemical purchase and disposal costs are lower

• Risk of an accident from adding too much hydrogen peroxide is eliminated

Overall process results and wet etching performance are improved with the better outcomes and reduced costs of a Piranha etch process using Modutek’s “Bleed and Feed” process control. Customers incorporating Modutek’s new control strategy can expect reduced product failure rates, better output quality and overall improved wet process station performance.

Modutek continues to improve their silicon wafer cleaning equipment to provide customers with better process results using the “Bleed and Feed” process control in new wet bench stations. The company offers free consulting and can help customers choose an appropriate wet bench configuration or custom-build one to meet specific customer needs.

Modutek’s History of Innovation, Customer Support and Satisfaction

Modutek's History of Innovation, Customer Support and SatisfactionWith 40 years of success as a manufacturer of wet bench stations and semiconductor equipment, Modutek Corporation continues working with customers to improve process results and meet customer needs. The company emphasizes the following three aspects of its operations.

1. Constant innovation, looking for aspects of wet bench technology that could be improved and finding solutions that produce excellent results.

2. Customer support. Because Modutek manufactures all its own equipment, it has the expertise to provide unparalleled support for everything the company delivers.

3. Customer satisfaction. Modutek uses raw materials and parts of the highest quality to deliver equipment that meets or surpasses customer expectations.

By building its operations around innovation and customer needs, Modutek has become a leading semiconductor equipment manufacturer.

Manufactures Reliable Equipment of the Highest Quality

The key to producing reliable equipment is to use high-quality inputs for proven manufacturing processes. When manufacturing wet bench components with materials such as quartz, Teflon and stainless steel Modutek specifies the highest quality and produces equipment with an excellent track record. The high equipment reliability results in low down times and high-quality output for customers.

Innovation that Provides Customers with Solutions

Modutek’s customer-centered approach directs innovation towards addressing customer problems. The company works closely with customers to learn about their needs and then develops solutions that incorporate the latest technology to improve process results.

Wet Bench Equipment that is Designed, Built and Programmed In House

Customers ordering wet bench equipment from Modutek receive one-stop solutions with no third parties. During concept, configuration and design customers work with Modutek specialists to translate their needs into wet process systems that can carry out the functions they want. Manufacturing is done at the company’s plant in San Jose and the software used in process automation is written and programmed by Modutek’s own engineers. With no third parties to call in and a seamless knowledge of the delivered systems, Modutek can provide exceptional service and support.

Delivering a Comprehensive Suite of Wet Process Equipment

Modutek is a wet bench manufacturer with a complete line of wet process equipment including complete systems, individual stations and process components. Stations can be manual, semi-automated and fully automated and they can incorporate auxiliary functions such as an IPA vapor dryer or chemical handling station.

Components making up wet process systems include Quartz tanks/baths, Teflon tanks, Solvent baths, Megasonic cleaning, Air Scrubbers, waste water treatment systems and Quick Dump Rinsers. Modutek can offer such components to be added to an existing facility or can assemble standard components to meet specific customer needs. In each case, Modutek can help establish what is required for a wet process application and recommend equipment from its own comprehensive line, ensuring that the equipment performs as expected.

Modutek Can Design a Custom Solution for all Wet Process Applications

Semiconductor manufacturing has many steps and an application often has unique requirements. Prototypes, models, research projects or proof of concept products can each require custom solutions. While Modutek has standard components in its product line, the company can modify its standard designs to meet specific customer needs.

Because Modutek builds all its products in house, it has the capability to change dimensions, use special materials, and integrate additional functions into a system or program how specific processes run. Tanks and baths can be built to fit existing spaces or match existing facilities. Wet bench stations can be programmed with exactly the right amount of automation, adding operator interventions at critical points. With its in house expertise, Modutek can examine customer requirements and build the corresponding equipment.

Combining 40 years of experience with its comprehensive wet process equipment product line and its extensive customization capabilities lets Modutek satisfy customers with effective results. Modutek also backs up its equipment with superior customer service and support. That record together with its innovative products makes Modutek one of the leading semiconductor equipment manufacturers.