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 Specialized Manufacturing Equipment Provides Safety for Using Solvents

Semiconductor manufacturing solvent applications use specialized wet bench equipment to reduce the risk of fire and explosions from volatile solvents such as acetone. Solvents are used for operations that include stripping, cleaning and pattern transfers, and their inflammable nature means that the equipment has to meet stringent safety regulations. Safety measures focus on ensuring electrical components don’t ignite solvents or their vapors and operator safety through training. Additional safety measures include limiting access to sensitive areas and installation of fire extinguishing equipment. These safety measures provide integrated approach to solvent handling and use and ensure stainless steel solvent stations can be installed and operated safely in new fabrication lines or with existing equipment.

Special Features Satisfy Regulations and Keep Operators Safe

When working with inflammable solvents, safety regulations require specific features and additional operating measures to keep workers safe. These features can include the following:

Design to hazardous location Class 1 Division 1 or Division 2 certification.

Design electrical equipment to use low-power signals too weak to generate sparks that could set off an explosion.

Use of carboys to collect solvent waste.

Use of safety interlocks to ensure safe operation.

Process monitoring with safety alarms for dangerous conditions.

Detection of liquid spills.

Emergency power off mushroom button.

Wiring per NFPA 70 and 79.

Auto lids to seal off chemical containers.

Access controls to ensure only qualified personnel can operate the equipment.

Gaseous automatic fire suppression systems such as those using carbon dioxide.

An experienced manufacturer of wet bench equipment incorporates these features in all their solvent station designs to make sure an integrated safety concept allows for safe operation.

Modutek’s Stainless Steel Solvent Stations Meet All Safety Requirements

Modutek manufactures the SFa and the Sa series of stainless steel solvent baths for solvent applications including IPA, acetone and resist strippers. The baths meet National Electrical Code Class 1 Division 1 Group D requirements for hazardous locations and are specially designed for safe operation. Made from 304 stainless steel, the baths are inert for the solvents used. The SFa bath is a temperature controlled recirculating bath while the Sa bath is constant temperature.

The baths both include all the required safety features for safe solvent operation. With NFPA 70 and 79 wiring, fire suppression, N2 head case purge, 1-inch lip exhaust and PVC safety shields, the baths are configured to keep workers safe. Operational safety is ensured with safety interlocks, an emergency off mushroom button, a Teflon N2 gun, a de-ionized water hand spray and a continuous flow de-ionized water manifold.

While maintaining a high level of safety, the stations deliver improved yields with fast heating and accurate temperature control. With an operating temperature of 30 to 100 degrees centigrade, heaters can achieve a temperature increase of up to 2 degrees centigrade per minute. Temperature control accuracy is plus/minus 1 degree centigrade for excellent process control and reproducibility.

Modutek’s solvent stations are available in fully automated, semi-automated or manual versions. The fully automated stations further increase safety by eliminating operator error, reducing spills and ensuring that a process runs with the correct dosages and timing. Semi-automated stations give customers the benefit of robotic operation without paying the price of full automation. Manual stations retain all the safety features but don’t include automation and are less expensive. Each station can be customized to exactly meet the specific requirements of the customer.

As a wet bench manufacturer with extensive experience in semiconductor manufacturing technology, Modutek can design and build both standard and customized equipment that is safe to operate while delivering top performance. Modutek can provide free consulting to help customers clearly define needs and then propose wet bench components, standard systems or custom installations that meet the highest safety standards.

Why Custom Wafer Cassettes Are an Essential Part of Wet Bench Equipment

Custom wafer cassettes made of specified materials or with specific physical characteristics are often needed in wet bench equipment for some applications. Research labs and universities may create unique semiconductor prototypes and start-ups may need sample semiconductors for testing. In each case, off-the-shelf carriers with the required characteristics are often not available. Custom wafer cassettes ordered in low volumes can meet the requirements of research and testing facilities and allow them to carry out the specialized silicon wafer fabrication they need.

Custom Wafer Cassettes are Needed for Research Applications

Research labs may need wafer carriers with unusual characteristics because they are testing new processes or using new materials. Universities may be trying to re-create a historical process or develop a new process that requires cassettes not commercially available. These organizations often need only a few of the custom cassettes to carry out their research and testing. The availability of custom wafer cassettes without a minimum order quantity is a key factor in the ability of the labs to carry out their research and testing.

Start-Ups Need Special Cassettes to Create Prototypes

When a start-up develops an innovative semiconductor product, off-the-shelf wafer cassettes may not be suitable because the product is not currently being produced commercially. The new product may require special processing and the wafer carriers used may have to use an innovative design or material as well. To produce different prototypes and test them in real-life situations, start-ups may need a series of custom wafer cassettes before they begin commercial production of their new product.

Up-graded Production Lines May Require Custom Cassettes

Modified production lines mean that some equipment has to be changed and other equipment adapted. Such modifications can take place as a result of changes in suppliers, updated regulatory requirements or new customer demands. Often parts of the production line are replaced or additional equipment is retrofitted. Large items such as tanks and baths may be kept but re-purposed. If wafer cassette operation is affected, new off-the-shelf cassettes may not be suitable and custom wafer cassettes, adapted to the new processing line, may be the best solution.

Modutek Can Provide Custom Wafer Cassettes

Modutek is a leading manufacturer of wet bench equipment that has in-house expertise to analyze customer requirements and deliver custom installations of the highest quality. With extensive experience in all aspects of wet bench technology, Modutek can offer equipment from its standard line of wet bench stations but can also meet special requirements because all equipment is designed and built in house. Once the details of an application are clear, Modutek can build the components so they meet any special requirements.

When custom wafer cassettes are needed, Modutek can design and build custom units as needed. The company has the capability to design and build special configurations and to use specific materials such as PFA Teflon, PFTE Teflon, PVDF and Natural Polypro. Custom carriers can hold between one and twenty-five wafers per carrier and carrier design can be optimized for a specific use. To emphasize its commitment to meeting the special needs of customers, Modutek does not require a minimum order quantity for custom wafer cassettes.

Semiconductor manufacturing is always complicated and a degree of customization is often needed to fulfill the requirements of a specific process. As the business environment of a semiconductor manufacturing facility changes, production lines have to be modified and the changed equipment has to be customized to fit the new configurations. Modutek can help identify such custom requirements and provide the corresponding custom equipment. Custom wafer cassettes are one specific case where Modutek can supply special components that are not otherwise available. Contact Modutek for a free consultation or quote on equipment needed for your specific requirements.

5 Important Things to Know When Buying Wet Bench Stations

Because semiconductor manufacturing relies on a large number of process steps and complicated sequencing, wet benches need to be tailored to meet requirements for a specific application. Before focusing on the process-specific requirements, there are general questions that should be answered. This helps narrow down the selection criteria before making the purchasing decision.

General questions include the level of automation, whether stainless steel solvent stations are required, whether a chemical delivery system is needed and whether any special options for rinsing and drying would be beneficial. Any process steps that require special etching or cleaning equipment can then be considered. Such a structured approach helps with selecting the best wet process station configuration and with integrating special equipment within the wet bench station.

1. Automated Wet Bench Stations

Modutek’s product line of wet benches can be fully automated, semi-automatic or manual. Fully automated stations can run batches without operator intervention and offer excellent repeatability if the same product is manufactured several times. Reliable processing with the use of the Modutek SolidWorks Simulation Professional and SolidWorks Flow Simulation software helps increase throughput and yield.

Semi-automatic stations provide the same increased safety and reduction of human error as fully automated stations without the higher price of full automation. Servo-controlled robots provide high precision and reduce handling. Manual stations are a low-cost option that offers all the process features of the automated stations without the robotics and the cost of automation.

2. Stainless Steel Solvent Stations

Modutek stainless steel stations are an excellent solution for solvent applications. They are available in the manual to fully automated versions and in dry-to-dry configurations. Like the acid stations, they can be used with the Modutek SolidWorks Simulation Professional and SolidWorks Flow Simulation software to calculate chemical doses and the process parameters. Solvent station design can include fume hoods and all stations satisfy fire safety standards.

3. Chemical Delivery Systems

Whether a chemical delivery system is needed depends on the volumes and types of chemicals used in the fabricating process. Chemical delivery systems help avoid spills and make tracking of chemical neutralization and disposal easier. Modutek can custom design the system to exactly meet the needs of an application and a key factor for using a chemical delivery system is when high precision is needed for the chemical dosages.

4. Rinsing and Drying

Once an etching or cleaning process step is complete, the wafers have to be rinsed and dried without introducing any contaminants or particles. Rinsing and drying equipment can fulfill special requirements and improve the process. For example, the Modutek IPA dryer combines rinsing and drying in one station while the quick dump rinser improves process efficiency. Both reduce particle contamination and improve process yields.

5. Special Etching or Cleaning Equipment

Some semiconductor fabrication may require special equipment for specific etching or cleaning process steps. For example, etching of aluminum layers on wafers or the removal of submicron particles can be carried out with wet bench equipment that Modutek has specifically designed for the purpose. Modutek’s Vacuum Metal Etcher automatically etches aluminum layers with great precision and immediately removes hydrogen bubbles as they are generated. In addition Modutek can incorporate the use of Megasonic cleaning equipment to dislodge and remove the tiniest particles from wafers to be processed. This and other kinds of specialized equipment can be integrated into the process line of a wet bench.

Modutek Can Help With the Final Selection

Once customers know the things mentioned above and the requirements of their wet process application, Modutek can suggest appropriate solutions from their complete line of wet process equipment. The company designs and builds all its own equipment and meets standard industry certifications of compliance. Because the work is all done in house, Modutek can customize equipment easily and can offer outstanding customer support and service. All equipment is tested before delivery and includes a comprehensive warranty.

Ordering a Wet Bench Station for Your Specific Process Requirements

Semiconductor manufacturing requires many process steps that must be followed and controlled in a very precise manner. Process requirements can include cleaning, etching, developing and stripping. Handling the aggressive chemicals means special attention has to be given to safety and disposal. The physical characteristics required in the production line have to be considered as well. Special features such as recirculation, heating, additional process control and degree of automation can be ordered.

Not all semiconductor equipment manufacturers can offer a complete line of wet bench stations incorporating the latest technology and using their own software. The many options and differing process requirements mean that almost every installation is customized to some extent. An experienced supplier who can provide advice and deliver the best systems is needed for achieving optimal results.

Physical Requirements Affect the Ordering Process

The three types of physical factors influencing the wet bench equipment specifications are the available space, wafer size and wafer throughput. Limited space for new installations or a requirement to integrate with an existing system may mean that compact stations are required. The baths must be able to accommodate the wafer size proposed for the application. Throughput is governed by the number of cassettes that can be processed per bath, the number of stations, the estimated process duration and the estimated downtime for replacing chemicals, maintenance and other process-related factors.

Space limitations are often critical. Factors that can reduce space requirements are what functions a station can execute and whether some functions, such as rinsing and drying, can be combined or need separate spaces. Chemical delivery systems can take space or might be placed remotely or behind the productions line. Such questions can be explored with a qualified supplier.

Throughput is often a critical variable affecting profitability. Automatic transfer of wafers between stations and automatic process control may save time. How the process is controlled, for example in a piranha “feed and bleed” type of operation, may affect how long a chemical bath can be used without changing the chemicals and may also affect downtime for maintenance. Often advanced technology from a leading supplier can increase throughput.

Wet Bench Equipment, Controls and Accessories Have to Support the Process Chemistry

Wet bench processes such as RCA clean, KOH and Piranha use highly aggressive chemicals. The equipment has to resist the corrosive substances and feature safeguards to keep operators secure. Some processes, such as silicon nitride etching, have to have special controls. Processes using especially dangerous chemicals such as hydrofluoric acid require additional safety measures.

Equipment for specific wet bench processes can include the following:

  • Quartz baths for cleaning etching and stripping applications. High temperature recirculating or constant temperature baths.
  • Teflon tanks for etching applications. Heated, recirculating and ambient temperature.
  • Silicon nitride wet etching bath. Special control features for silicon nitride removal with phosphoric acid.

Semiconductor fabrication facilities, research labs and universities that require wet process equipment first have to make sure that prospective suppliers can provide equipment with the special features needed. Heating control accuracy and precise calculation of dosages is essential for high quality output and a low product failure rate. Suppliers who manufacture, assemble and program their own equipment can be relied upon for complete after sales support and service.

Modutek Can Help

Modutek has worked closely with semiconductor fabricators and has extensive experience in providing semiconductor manufacturing equipment. The company assembles its own systems in their San Jose California facility and company specialists program their own software and controls. Modutek has state of the art wet bench stations and has pioneered improvements for processes such as silicon nitride removal and Piranha etching. With its in house expertise, the company can analyze customer requirements and propose the best solutions.

Reviewed and Approved by Douglas Wagner
President & CEO, Modutek Corporation

Why Preventative Maintenance of Wet Bench Equipment is Important

Why Preventative Maintenance of Wet Bench Equipment is ImportantTimely preventive maintenance of wet bench equipment allows semiconductor manufacturers to avoid costly unexpected downtime due to equipment failure and quality issues. Wet bench equipment is complex and is typically used in a demanding manufacturing environment. Calibration, cleaning and replacement of parts that wear out has to be performed regularly to maintain facility performance and output quality. Once scheduled, preventive maintenance has to be carried out quickly and professionally, completing the required tasks on time and using personnel with the required expertise. If the necessary preventive maintenance is not completed or is not done correctly, poor quality products, equipment damage and compromised worker safety can result.

Scheduling Preventive Maintenance

Wet bench stations operate with corrosive chemicals while at the same time relying on the highest standards of cleanliness and control of contamination. Chemical dosages and control of variables such as temperature are critical for a successful production line. Some components have to be changed, cleaned or serviced regularly while others have to be inspected to see if any action is required.

The semiconductor manufacturing equipment supplier will often specify what preventive maintenance measures are required and which ones are recommended. Some tasks can be carried out by the semiconductor manufacturer’s personnel, but others will often require specialists from the supplier. Developing an overall schedule that limits downtime for the production line to a minimum while ensuring that all preventive maintenance tasks are scheduled and carried out can be challenging.

Carrying Out Preventive Maintenance

Depending on the details of the semiconductor manufacturing operation, some preventive maintenance tasks can be performed while the line is in operation. For some lines, production steps are sequential so that a particular piece of equipment may be at rest for a given period. Preventive maintenance can then be carried out on that equipment.

Other parts of the production line may be in more or less continuous use for periods exceeding the recommended preventive maintenance interval. In such cases the required downtime has to be factored into the production schedule with reduced throughput. When all these factors are taken into account, it becomes clear that preventive maintenance for wet bench equipment may have to be flexible and reactive to manufacturing requirements rather than based on a fixed schedule.

Coordinating with a Competent Supplier

Developing an ongoing wet bench preventive maintenance program is easiest when partnering with a supplier who is familiar with the installation and who can handle all preventive maintenance tasks, even if the stations are highly customized. Such a supplier can help the semiconductor manufacturer develop and adapt a suitable schedule and help complete the work. The supplier can offer to carry out those tasks that specialists can perform quickly and competently while giving instructions for on-site semiconductor manufacturing personnel to complete simple tasks and inspections. Such an approach is ideal from the facility owner’s point of view.

Modutek can offer this type of field service and customer support because it has in house expertise based on almost 40 years of experience in the wet processing technology field. Scheduling and carrying out preventive maintenance on wet bench stations while keeping disruptions to production at a minimum requires such experienced personnel.

In addition to highly qualified specialists, Modutek designs and builds all its own wet bench stations at its manufacturing facility in San Jose. As a result, it can offer first-hand service, repair, and upgrade support without having to call on third parties. Working with a competent partner such as Modutek helps customers carry out the necessary preventive maintenance that keeps their equipment functioning at an optimum level while reducing downtime and avoiding compromised product quality.

Reviewed and Approved by Douglas Wagner
President & CEO, Modutek Corporation

 

How to Safely Use Solvents for Wafer Processing

how-to-safely-use-solvents-for-wafer-processingAt semiconductor research centers and foundries, solvent wet bench stations provide a critical role in the semiconductor fabrication process. These stations are designed for operations that include substrate cleaning, photoresist stripping and liftoff pattern transfers. Since the solvents are often highly inflammable, wet bench equipment needs to be designed with stringent compliance to safety codes.

Equipping for safety

Precautions related to fire safety and electrical safety is among the most basic requirements in wet bench station design. Fire suppression can involve the application of spark-resistant electrical design all around, and the provision of extinguisher equipment. Solvent wet bench stations must be designed to meet Class 1 Div 2 certifications, and incorporate a carbon dioxide (CO2) fire system.

Safety alarms: Exhaust, CTA and N2 safety interlocks should monitor for use within acceptable ranges. Safety doors on the head case and elsewhere should be monitored during use and should be able to shut down operation if they are opened during use. Float switches should detect liquid spills on the floor of the bench. Differences in pressure between the exhaust on the bench and the rest of the room should be monitored through the use of photohelic gauges (low readings indicating incorrect operation should sound an alarm).

Carboy collection: Since solvent waste should never be sent down the drain, carboys help collect waste for containment. Multiple containment volume sizes are available.  All come with current safety interface.

Heated solvent baths: Temperature control is achieved in many ways, and heated baths are one of them. They should be used to control the temperature of the solvents being used. Temperature controllers should be used both to raise and lower temperatures and to monitor temperatures.

Process timers: These vital pieces of equipment should be mounted to the head case to ensure that personnel are able to keep track of how long each process is to run.

Restrictions on use: A login system should ensure that only authorized individuals are able to access the bench.

In many cases, safety comes from simpler approaches — the use of auto lids made of Teflon or stainless steel to help seal off chemical containers.

Modutek’s Solvent Wet Bench Equipment

Available in manual, dry-to-dry, semi-and fully-automated designs, Modutek’s stainless steel solvent stations are constructed all through using 304 stainless steel. Solvent applications require the use of this material. From photoresist to IPA, and acetone, these stations are suitable for critical operations in the wafer processing activities. From solid works simulation to professional flow simulation, many critical flow characteristics are available. Improvements to productivity are achieved through the use of Modutek’s advanced software.

Modutek’s safety design for solvent processing involves every required feature. With wiring specified to NFPA 70 & 79 codes, emergency power off design for every safety interlock, lip exhausts on all solvent tanks, N2 head case purge design, photohelic EPO interlocks, safety shields, Teflon N2 guns, and continuous flow of the water manifolds, Modutek’s designs are among the safest of all wet stations.

With a chemical management interface, a PCL with touchscreen GUI, a rear access design, Teflon plumbing throughout, certification to the CE Mark, and seismic certification, Modutek’s equipment incorporates features beyond legally required safety measures.

Modutek’s Wet Bench Design and Build Process

Wet bench construction is a complicated process, and Modutek provides systems that are designed to meet the requirements of specific applications of individual customers. With 35 years in the business, Modutek understands that acid and solvent processing for micro fabrication requires customized solutions. Modutek’s designs and builds all their wet bench stations in house to ensure every part of the system provides reliable performance. If you need a solvent wet bench station designed and built to meet your requirement s contact Modutek for a free consultation or quote.

 

How Wet Bench Stations Are Tailored for Specific Manufacturing Process Requirements

The fabrication of semiconductor wafers requires that an elaborate set of chemical etching, stripping and cleaning steps be followed in a precise procedure that can be consistently repeated. The semiconductor manufacturing process requires that the use of hydrofluoric acid and other chemicals which must precisely controlled and monitored. These high-tech processes are critically important to industries that fabricate semiconductors, medical equipment and photovoltaic cells. They require the use of custom-made wet benches designed to assist in the safe and precise control of corrosive chemicals at high temperatures.

Wet bench equipment

Modutek provides a full range of wet bench equipment to address the specialized needs of semiconductor manufacturing facilities and research centers. Wet bench stations can be tailor made according to the specific manufacturing process requirements of a customer.

Citric-nitric passivation wet benches are critical to the passivation of titanium and stainless-steel parts in various industries. Electro-polishing wet bench equipment is deployed in the medical device industry in the manufacture of precision steel, cobalt chrome and titanium components.

Multistage wet process fume hoods with circulation pumps are used in aerospace component manufacture, printed circuit board fabrication, and the semiconductor manufacturing industry. Modutek’s wet bench equipment for the semiconductor industry meets UL2360/FM4910 standards for fire and contamination safety. This enables fabricators to remain compliant with applicable environmental laws.

Titanium anodizing equipment, agitated immersion washers, in-line conveyor washers, spray cabinet washers and other precision equipment are an integral part of the semiconductor industry, as well. Modutek is an industry leader in the design, development and deployment of these and many other kinds of wet bench equipment.

The precision needed in manufacturing equipment

Sulfuric acid-peroxide is a powerful chemical that is critical to the cleaning processes applied to semiconductor wafers. Effective application of this chemical mixture is inherently unstable and requires constant rebalancing. The rebalancing and control is needed to maintain efficiency. The mixture needs to be constantly replenished with hydrogen peroxide at high temperatures, something that can be costly even in simple material costs. Modutek’s high-tech systems not only ensure the correct concentration levels, they also help fabricators contain material costs through the use of an exclusive chemical re-use system to contain material costs. Every part of the process is maintained and monitored by equipment that is software controlled.

The silicon nitride wet etching process is another semiconductor fabrication stage that requires a high level of precision and control. Silicon nitride is used to mask chemical etchings on silicon wafers. Once an etching successfully completes, the masking material requires removal. Typically, a mixture of phosphoric acid and the ionized water is applied. Precise control over the chemical mixture is needed, however, if only to prevent the risk of dangerous heat levels and explosions. Modutek’s wet bench station design addresses this challenge through the use of high-tech safety features and the use of precision software.

Modutek’s in-house design process

From manual to semi-automated and fully automated wet bench stations, Modutek’s products are designed and developed in-house right down to the software. From servo-controlled robots and automated equipment to low-cost manual stations, Modutek’s equipment covers the needs of the industries they serve. With their in house expertise and 35+ years of operation, the company is well equipped to meet and support the requirements of semiconductor manufacturers and research centers. Developing equipment that provides thorough and precise control of the manufacturing process is what sets Modutek apart from other semiconductor equipment manufacturers. Contact Modutek today at 866-803-1533 for a free consultation or quote on wet bench equipment that can be tailor made to support your specific manufacturing requirements.

 

Changes to the SPM Process Improves Efficiency and Results

The sulfuric acid hydrogen peroxide mixture (SPM) process effectively strips and cleans wafers but suffers from instability due to the decomposition of the hydrogen peroxide. A heated bath improves performance but increases the rate at which hydrogen peroxide changes into water. Periodically spiking the mixture with extra hydrogen peroxide can restore the required concentration but affects the strip rate. As a result, the SPM mixture has to be changed frequently, leading to high costs for chemicals and frequent downtime on wet bench stations. Working closely with a local semiconductor manufacturer, Modutek has developed a “bleed and feed” process upgrade that addresses these problems and results in substantially longer mixture life and improved process results.

The SPM Process

A typical mixture for the SPM strip and clean process is one part hydrogen peroxide to three parts sulfuric acid. The sulfuric acid parts can go as high as 7 parts but once the process has started, if the concentration changes, the strip rate can change as well. The mixture is heated to 130 to 140 degrees centigrade to increase the strip rate. The higher the temperature, the faster the hydrogen peroxide decomposes to water, diluting the mixture.

To keep hydrogen peroxide in the mixture, more of the chemical is periodically added to the process, spiking the concentration back to its original level. Despite this, the mixture is normally usable for only a few hours at a time and typically has to be replaced several times a day. Replacing the mixture is costly and requires repeated downtime when processing has to wait for a new pour. In addition to the costs of the chemicals, there are treatment and disposal costs that are required to comply with environmental regulations.

Modutek’s “Bleed and Feed” Process Change

Modutek has developed a hydrogen peroxide spiking method that keeps the chemical mixture at a predictable concentration and avoids the requirement for frequent replacement. The method reduces consumption of the chemicals and lets the system run for extended periods without down- time.

Using a two-tank dirty and clean tank process, the “bleed and feed” method involves draining a programmable amount of mixture from the dirty tank prior to each process step. Another programmable amount is fed from the clean tank to the dirty tank. Then programmable amount of sulfuric acid is added to the clean tank and both tanks receive programmable amount of hydrogen peroxide.

When the entire mixture has to be replaced, normally about once every week, the system has a quick drain feature that reduces down time and gets the process up and running again quickly. The whole “bleed and feed” spiking method is PLC controlled and the periodic adding and spiking of chemicals allows the mixture to be used continuously for days at a time.

Benefits of the Modutek Process Change

In addition to savings related to the reduced use of chemicals, the new update improves overall efficiency and achieves better results. Instead of having to shut down the wet bench station every shift to pour new acid, the process can run for days and only requires a complete chemical change once per week. In addition, the process is cleaner and can deliver better cleaning and stripping performance.

Modutek is offering the SPM process upgrade on their new wet bench stations and can provide details regarding chemical use and performance. The company has the experience and expertise to help customers more effectively use the SPM and other processes to ensure they obtain the results they need. Call Modutek at 866-803-1533 for any questions you have with using either the updated SPM process or other wet processes needed for your application.