How Megasonic Cleaning Improves the Silicon Wafer Cleaning Process

How Megasonic Cleaning Improves the Silicon Wafer Cleaning ProcessAs silicon microscopic circuits and structures shrink in size, the elimination of contaminants from becomes increasingly important. When silicon wafer cleaning is effective, it removes particles as small as 0.1 µm to prevent them from affecting the silicon fabrication process. Traditional wafer cleaning with chemicals may leave some of the smallest particles in place and production line output quality can suffer. The semiconductor components produced may be of inferior quality or fail completely. Megasonic cleaning with sound waves in the MHz range generated in a water cleaning solution can remove particles down to 0.1 µm in size and improve cleaning performance.

How the Megasonic Process Cleans

The Megasonic Cleaning System consists of a high-frequency generator, transducers that convert the electric signal from the generator to sound waves in the water, and a cleaning tank to hold the cleaning solution and the silicon wafers. Sound waves in the MHz frequency range travel through the cleaning liquid and generate microscopic cavitation bubbles in the low-pressure wave troughs. When the bubbles collapse in the high-pressure wave peaks, they produce tiny jets of water.

When the bubbles collapse near a wafer, the resulting jets hit the silicon and dislodge any particles adhering to the surface. The particles are carried away by the water currents and the microscopic bubbles are so numerous that all surfaces are cleaned. The bubbles and the cleaning effect are present throughout the liquid and they penetrate into holes, crevices and microscopic structures, cleaning completely.

Megasonic Cleaning Benefits

In addition to cleaning silicon wafers and removing microscopic particles more effectively than traditional cleaning methods, Megasonic Cleaning provides several other benefits over the use of chemicals. The rise in output quality is accompanied by lower costs, a safer process environment and shorter process times.

When a semiconductor fabrication facility uses fewer chemicals for cleaning wafers, costs decrease. The facility has to purchase smaller amounts of chemicals, storage costs are lower and costs for disposal are less. Depending on the process, Megasonic Cleaning may allow a facility to eliminate certain chemicals completely, resulting in even higher savings.

The Megasonic Cleaning process is safe and environmentally friendly. The megasonic waves and the cleaning solution do not present any danger to equipment or operators who can set a timer and come back when the cleaning process is finished. The water-based solution is not toxic and does not require special disposal. Compared to chemical cleaning, the storage and handling of Megasonic cleaning materials is safe and easy, power consumption is lower and less water is required.

Modutek’s Megasonic Cleaning System

The Modutek Megasonic Cleaning System was developed together with ultrasonic technology leader Kaijo Corporation to reflect the specific demands of silicon wafer cleaning. The high operating frequency in the MHz range ensures gentle but effective cleaning of delicate materials without pitting the silicon surface or damaging the silicon wafer structures.

Modutek’s partnership with Kaijo lets the company offer an integrated system that features the Quava Megasonic generator and transducer within Modutek’s cleaning baths. Megasonic’s baths are available in the indirect heating MSI series that can heat the cleaning solution up to 140 degrees centigrade while the direct heating MSD series can heat the cleaning solution up to 70 degrees centigrade. Both baths are ideal for submicron particle removal with a high power density and high efficiency.

The Megasonic System is available with 600 W, 900 W and 1200 W power ratings at the standard 950 kHz frequency. Frequencies of 200 kHz, 430 kHz, 750 kHz and 2 MHz are also available for applications that require the more robust cleaning action from the lower frequencies or for very delicate components at the higher frequency. In any case, Modutek can advise customers to make sure they select the ideal Megasonic Cleaning configuration for their specific silicon wafer cleaning applications.

Tips on Selecting an Acid Neutralization System for your Application

Tips on Selecting an Acid Neutralization System for your ApplicationAcid neutralization systems are essential for various industrial processes such as semiconductor fabrication and research facilities that produce acidic effluents. These cannot legally be discharged directly into public sewer systems; instead, they need to first be processed in legally prescribed ways. Altering the pH of acidic waste by-products to legally acceptable pH ranges of between 6 and 9 can be a major challenge, however.

As process engineer or semiconductor facility manager, what do you look for in an acid neutralization system? The best solution is a system that is easy to use, has a low operating cost and complies with all laws and regulations. Managers tend to see waste treatment as an operation that is difficult to administer and control costs in. The use of an effective system that provides automation would be the best option.

Automation frees up resources and lowers costs for businesses. When equipment is properly maintained to manufacturer-recommended specifications, a business can easily manage the process to meet specific criteria.

Acid neutralization systems treat acidic effluents using either continuous-flow processing or batch processing.

Considering a Continuous-flow Neutralization System

Continuous flow neutralization — where a stream of influent is treated while in flow through a pipeline system, prior to discharge — tends to work well in applications where there is a high rate discharge of mild acid or alkali. Continuous flow systems tend to be practical as long as the pH of influents remain stable from one moment to another.

Most systems offer a two-stage handling process; these can be effective for processes that produce moderately acidic effluent. Three-stage processes work well for processes that produce especially polluted effluents.

An automated, continuous-flow neutralization system is designed to provide acid neutralization within the confines of a compact unit, and can process streams as high as 500 gallons per minute.

With microcomputer-controlled monitoring at every stage, there is a high level of reliability to ensure compliance.

Considering a Batch Neutralization System

Acid neutralization systems that handle influent waste acid in batches can be effective in certain applications. Unlike continuous flow systems, batch systems are able to effectively deal with complex, highly acidic influents. Batch systems are suitable in the treatment of processes that cannot be relied upon to produce effluents of stable character. When acidic content tends to change, batches of waste need to be collected and treated separately. Batch neutralization systems also excel in the treatment of influents that are complex in nature — ones that contain heavy metal and fluorides.

These systems come with excellent automation benefits that include:

  • The automation of chlorination and pH adjustment for removal of bacteria.
  • The programming of operational sequences where different reagents and polymer flocculants are fed in.

The Benefits of Choosing an Automated Solution

With an automated acid neutralization system in place, manufacturers are able to get by with a minimal amount oversight to this side of operations. Fully automated from end to end, these systems offer intelligent, sensor-based checks at every point to alert staff of any need for attention, should it arise. Operators can be assured that problems will not go unnoticed.

Modutek Can Help You Choose the Right System for Your Requirements

Modutek, a leading provider of equipment solutions for semiconductor manufacturers, offers a full range of neutralization technologies with different configurations. These are highly cost-effective systems both to install and operate. Modutek can assist process engineers and managers at manufacturing facilities to select the right equipment to meet their specific requirements.

How Teflon Tanks Are Used in Wet Processing Applications

How Teflon Tanks Are Used in Wet Processing ApplicationsModutek’s Teflon tanks are custom designed for use in new and existing wet processing stations. Their modular configuration allows easy integration in customer clean room facilities. Advanced PFA Teflon welding techniques reduce impurities and unwanted by-products in the process, and Modutek can supply heated models for use in processes that require temperature control. Standard carrier sizes are available for single or double capacity, and Modutek can design and build custom tanks for specific customer requirements. Additional options and features make Modutek’s Teflon tanks suitable for a variety of wet process applications.

Teflon Tank Configurations

Modutek offers three types of Teflon tanks:

  • The TT series are ambient temperature baths
  • The TI series are temperature controlled static baths
  • The TFa series are temperature controlled overflow recirculating baths

Modutek can work with customers to analyze their process requirements and recommend the best tank configuration. All tanks are manufactured from the highest quality material and come with first-class support from in house technicians at Modutek.

Temperature-Controlled Teflon Tanks

Modutek offers static and recirculating temperature-controlled Teflon tanks for KOH (potassium hydroxide) and TMAH (tetramethyl ammonium hydroxide) anisotropic etching of silicon. The heat sources can be in line and an immersion heater in the overflow weir. The tanks feature all-Teflon fluid paths and low level, high limit and high-temperature signaling. A drain interlock is standard.

The temperature control delivers fast heating of two to three degrees centigrade per minute within a range of 30 to 100 degrees centigrade. Process temperature control is accurate to within plus/minus 0.5 degrees and the tanks feature an optional Teflon refluxor with Teflon cooling coils. The fast and accurate temperature control system lets operators achieve excellent consistency and repeatability for temperature-sensitive processes such as TMAH and KOH etching.

Teflon Tank Features

Modutek designs their Teflon tanks for ease of use, convenient installation, quick repair and excellent compatibility with new or existing customer facilities. Specific features include:

  • 360-degree serration overflow
  • Manual cover with overlapping seal
  • Modular design
  • Minimal water loss
  • Consistent chemical concentration over time
  • One year warranty

The design of Modutek’s Teflon tanks results in fewer defects in output and a higher product quality overall.

Teflon Tank Options

Modutek tanks can be ordered with the following options:

  • A pneumatically operated automatic cover
  • Teflon gravity drain system
  • Aspirator valve system
  • An RS232 Interface
  • Remote operation timer switches
  • Temperature process controller/timer
  • Teflon refluxor with Teflon cooling coils
  • Magnetic stirrer for agitation
  • DI water or IPA spiking system

Benefits of the Modutek Teflon Tanks

Modutek’s design and configuration results in the following specific benefits:

  • Uniform heating throughout the bath
  • Accurate and rapid temperature control
  • Process etch variability wafer to wafer less than 2 percent
  • Modutek in house maintenance and repair support
  • Extensive customization to meet specific requirements

Based on the standard Teflon tank design, Modutek can use its design expertise to supply Teflon tanks of the highest quality, sized to customer specifications and with the features and options required for the customer’s application.

Modutek Support

With over 35 years experience in wet bench stations, Modutek can offer effective support for customer wet process applications. The company manufactures a full line of semiconductor fabrication equipment and can help customers analyze their needs. With its wet process expertise and its experienced technical personnel, Modutek can offer help with selecting the best possible wet bench equipment configuration. The company offers free consulting to ensure that customers select the right equipment. Whether it is Teflon tanks or a complete wet process semiconductor manufacturing line, Modutek can help determine what the requirements will be, suggest optimal solutions and deliver the appropriate equipment.

Tips on Improving Your Silicon Wafer Etching Process

Tips on Improving Your Silicon Wafer Etching ProcessSemiconductor manufacturing facilities and research labs need silicon wafer etching equipment that delivers accurate and repeatable results in a safe and reliable environment. The structures on semiconductor wafers and for micro-electromechanical systems (MEMS) have to be produced to meet tight tolerances and with no contamination by impurities or stray particles. An improved silicon wafer etching process depends on selecting the right etching process and using high-quality equipment, which are key factors for consistent output with a low rate of defects.

Silicon Wafer Etching Processes

Wafer etching is a multi-stage fabrication process and different chemical baths are used to achieve specific purposes. Process steps include cleaning, masking and etching of the wafers themselves or deposited metal. These steps result in the production of microscopic structures in the silicon wafer and in electrical connections where required. Key factors for improved etching performance are control of etching speed and the cleanliness of the fabrication environment.

Silicon nitride is used as a masking material and is etched with hot phosphoric acid. Key factors for improved results are the accurate control of the acid concentration and temperature through the addition of de-ionized water.

Piranha etching is carried out with a mixture of sulfuric acid and hydrogen peroxide. The etching solution cleans organic residue from silicon wafers and is often used to remove photoresist. Cleaning with piranha etching can be appropriate at various stages of the semiconductor fabrication process, and its effective application depends on the correct mixture and accurate control of the process.

The KOH etching process creates microscopic structures in the silicon using a solution of potassium hydroxide. Variables controlling the etch rate include bath temperature, KOH concentration, silicon crystal orientation and impurities in the silicon. Improved etching performance means tightly controlling the etch rate to get the precise structures needed.

Buffered oxide etch (BOE) uses hydrofluoric acid and a buffering agent to etch thin masking films of silicon nitride or silicon dioxide. If properly controlled, it results in a highly consistent and repeatable process that is compatible with photoresist.

The key to improving silicon etch performance is to use wet process equipment from a supplier that has the required experience and who can deliver high-quality equipment designed for excellent etching performance. Modutek has over 35 years experience in the field, and can advise customers on which equipment best supports their particular wet processing requirements and can offer standard or customized equipment as needed.

Etching Equipment Design Features

Choosing the right wafer etching process for each stage of semiconductor fabrication is important, but it is the design characteristics of the equipment that ensure improve etching results. Critical design features of Modutek’s etching equipment include the following:

  • Filtration and flow control. Filtered etch baths feature continuous filtration in the 10- to 0.2-micron range and reduced acid consumption.
  • Temperature control. Temperature controlled circulators can heat or cool an etching bath and keep the temperature at the required levels. Operating range is 10 to 60 degrees centigrade with an accuracy of plus/minus 1 degree.
  • Tank design. Teflon tanks for KOH etching are available in many configurations and in standard carrier sizes for single or double capacity. Quartz baths for a variety of etching applications including piranha clean are available in a range of sizes.

Modutek helps customers improve their silicon etching performance by advising them on the right equipment for their specific etching applications and by ensuring the equipment delivers accurate performance in a consistent way. When silicon etching processes are carried out reliably with repeatable results, facility productivity increases and output quality improves.

Designing Semiconductor Manufacturing Equipment for Ergonomics and Safety

Designing Semiconductor Manufacturing Equipment for Ergonomics and SafetySemiconductor manufacturing processes routinely use chemicals and procedures that could result in accidents if the manufacturer did not have a serious commitment to safety. Safety guidelines such as SEMI S2, published by the global industry association for microelectronics manufacturers, help manufacturers implement safe operating protocols. Ergonomic designs for semiconductor manufacturing equipment as described in SEMI S8 help ensure a safe operating environment by reducing operator strain and fatigue.

In semiconductor facilities, fire is one of the most damaging threats and burning plastic releases toxic fumes while contaminating clean areas. The Cleanroom Materials Flammability Test Protocol (Class 4910) or the FM 4910 specification allows manufacturers to specify the use of non-flammable materials for their equipment. A comprehensive approach to safety, including ergonomic design and the reduction of fire hazards is the most effective strategy for reducing accidents in a semiconductor manufacturing environment.

Prioritizing Safety When Purchasing Semiconductor Manufacturing Equipment

Installations that have been in operation for a number of years may no longer satisfy current safety standards or may not meet the safety goals of the owner. The purchase of new equipment is an ideal opportunity to upgrade existing safety features and to ensure that the new equipment is as safe as possible.

Modutek follows the SEMI safety and ergonomics guidelines to design equipment that is easy to use and doesn’t require excessive reach or strength to operate. Typical examples include the Modutek wafer holding tray and a swing-arm operator interface mount. The wafer holding tray on the Modutek wet benches includes a robot arm that moves the tray to the front of the station for optimal loading with a minimum of effort.

The Modutek operator interface is normally out of the way along the side of the station, but that position is hard to see when an operator is monitoring the process. The ergonomic design allows the operator to swing the interface out and angle it for optimal viewing. The swing arm can rotate along three axes so the operator can place it in whatever position is the most convenient. Once in position, the operator can lock it into place securely, so it doesn’t move inadvertently.

Both of these examples demonstrate how Modutek implements ergonomic designs to help operators and technicians carry out their work safely and with a minimum of effort. The result is often higher productivity, more satisfied employees and fewer accidents.

Reducing Fire Hazards on New Equipment

Traditionally clean rooms are fitted with sprinkler systems or other specialized fire protection. An array of sensors detects flames, smoke, chemical vapors or heat and triggers the fire extinguishing system. By this time contamination of the facility is severe and re-establishing clean room manufacturing capability is time-consuming and expensive.

Semiconductor manufacturers and research centers with clean room facilities can reduce the threat of a fire that could disable their production by minimizing the use of flammable materials. Many wet bench processes use corrosive chemicals in tanks and piping made of plastic or other normally flammable synthetic material. Modutek can support efforts to minimize the use of flammable materials by supplying equipment that meets the FM 4910 flammability specifications and reduces the threat of fire.

Increased Safety with New Equipment from Modutek

Modutek has over 35 years experience in designing and manufacturing wet bench stations. The company has a broad range of standard equipment and can customize all aspects of semiconductor manufacturing to meet specific specialized needs.

While Modutek wet benches have a high degree of safety and ergonomic design built in, special customer requests can always be accommodated. Specific safety features or special ergonomic requirements can be added if not already present, and additional precautions against fire and other hazards can be incorporated as needed. Modutek equipment already includes many safety features, but the company has the experience and expertise to meet any additional customer requirements.

Commercial Market Opportunities for MEMS Technology

Using KOH Etching for Batch ProcessingMicro-electro-mechanical systems (MEMS) is a technology that incorporates the use of microscopic devices ranging in size from several millimeters to less than one micron. They usually have both electrical and mechanical functions and often include parts that can move in response to process conditions, commands from outside the structure or commands from integrated electronics. Typical miniaturized MEMS devices include sensors, actuators and other microscopic structures manufactured on silicon wafers using similar techniques as for semiconductors. They are popular because they are inexpensive to fabricate and are easily integrated into systems containing electronic controls, often on the same silicon wafer.

MEMS Applications

MEMS were first used in the automotive industry and then found increased application in the medical and optical fields. Typical macroscopic functions that were taken over by MEMS counterparts were pressure sensors, inertial sensors and chemical sensors. The MEMS sensors were less expensive to manufacture and performed better than the corresponding large sensors. In addition, different sensors could be placed on one silicon wafer along with signal processing electronics. For example, one unit could measure chemical pressure, detect impurities and generate alarm signals.

As MEMS fabrication methods became more sophisticated, the systems were able to take on additional functions and include different structures. For example, today’s MEMS can include mirrors, gears, pumps, nozzles and valves. Associated electronics can evaluate the signals, perform complex analysis and send results to external receivers via radio frequency elements. Such devices are found in the automotive industry in car airbags, tires and fuel systems. Technical products such as ink jet printers, digital projectors, bar code readers and display screens use MEMS to reduce costs and miniaturize components. Medical systems and devices use the miniature MEMS for diabetic evaluation, insulin delivery, blood analysis and needle less injectors. As the number of applications increases, the market for MEMS continues to grow as does the interest in inexpensive, reliable and rapid fabrication methods.

How MEMS are Produced

To create the microscopic structures that make up MEMS, manufacturers use technology similar to that used to produce microelectronics. For silicon wafer based MEMS, the wafers are masked, etched and cleaned in multiple steps. Silicon wet etching is one method that offers a number of advantages.

Wet etching with potassium hydroxide, or KOH etching, is inexpensive and reliable. KOH is safe and etches quickly. Repeatability is good and the process can be controlled by changing the temperature, the concentration of KOH, the crystal plane orientation of the silicon and the doping concentration. The KOH process allows for very precise etching and it can be automated. Other methods of creating microscopic structures on silicon wafers are more expensive, more risky or not as reliable.

Modutek’s Support for the KOH Etching Process

Modutek offers a variety of wet bench processing options including KOH etching. The company’s KOH silicon etching tank is designed and manufactured in house and can be built to customer specifications to satisfy specific wet process requirements. Its design emphasizes cleanliness with an all-PFA construction and consistency in the process to deliver accurate etching results.

The tanks are manufactured to reduce impurities and contaminants to a minimum with the PFA sheet material welded together using advanced welding techniques. The resulting process tanks deliver excellent performance and high quality output. Custom installations to work with existing wet bench equipment are available. Modutek uses its experience in the wet bench process to ensure that customer needs are met and the equipment functions as expected. If you have challenging wet processing applications contact Modutek for a free quote or consultation on solutions that will address your requirements.

Choosing the Right Chemical Delivery System for Your Application

Choosing the Right Chemical Delivery System for Your ApplicationSemiconductor manufacturers and research labs have extensive chemical handling requirements and need a safe way to supply chemicals to the points where they are used. Key factors for choosing chemical delivery systems are the storage options that are available, the system performance in terms of precision and reliability and the software that can be used to ensure safe and accurate operation.

The chemical delivery systems have to be able to receive the chemicals in bulk, store them safely and conveniently, supply them to the point of use in the required quantities, neutralize them as needed and dispose of them appropriately. Custom configurations, fast chemical change and control options may also be important. Suppliers have to be able to evaluate customer needs and make recommendations based on their experience with chemical delivery systems.

Chemical Delivery System Features

An ideal chemical delivery system improves facility or manufacturing line performance by increasing throughput and producing better quality output. It accomplishes this by reducing manual interventions that can slow down the process and introduce errors. When chemicals are supplied to the point of use exactly as they are needed and with the exact composition required by the process, the facility can operate at optimal efficiency.

A key component of a chemical delivery system is chemical storage. Storage space near the process is often limited but adequate storage to avoid frequent container changes is needed. Ideally the chemical delivery system can continue to operate with integrated storage while a main storage container is being changed.

The mixing and delivery of chemicals to the point of use has to be safe, precise and reliable. Software can calculate the precise amounts needed while monitoring sensors can show chemical paths, levels and other process variables. Extensive and flexible control configurations let customers choose exactly how the chemical delivery system will operate. High quality materials ensure reliable operation and long-term safety. Facility managers and engineers choosing a chemical delivery system have to evaluate such features and check which suppliers have the expertise to recommend a good fit for their needs.

Modutek’s Chemical Delivery Systems
Modutek’s advanced chemical delivery systems provide all the required features and functionality mentioned above. Large tote chemical containers with load cell interfaces can eliminate the need for frequent drum changes when large volumes of chemicals are used. For smaller quantities, a 55-gallon drum system is available and both storage systems are designed for quick chemical changes. Systems have all-Teflon fluid paths with leak detection and sensing of up to four levels. The automated chemical deliveries are displayed on a touch screen that also shows the status of key components such as valves, pumps and alarms. Modutek’s SolidWorks Flow Simulation and SolidWorks Simulation Professional provide accurate chemical delivery calculations and the Modutek systems can be integrated with the company’s own wet processing equipment or adapted for each customer.

Modutek’s chemical delivery systems use software and components that are designed and manufactured at the company’s San Jose, California facility. As a result, Modutek can offer unparalleled service for all its equipment and can prepare custom designs for specialized requests. In addition to providing chemical delivery systems for wet process stations, Modutek systems are suitable for tech benches, plating stations, fume hoods, cleaning stations and acid exhaust hoods. By eliminating manual operator interfaces and ensuring accurate chemical concentrations and mixtures, the Modutek chemical delivery systems can help with increasing facility efficiency and reducing failure rates. If you need a reliable chemical delivery system for your application, contact Modutek for a free quote or consultation.

Using KOH Etching for Batch Processing

Using KOH Etching for Batch ProcessingEtching baths with varying concentrations of potassium hydroxide (KOH) and controlled temperatures are used in creating microscopic structures on silicon wafers. Modutek can supply equipment such as PFA Teflon tanks, circulation and filtering systems and cassette handling equipment that supports KOH etching. The company designs and builds individualized systems for customers who want to use KOH etching and the resulting systems deliver accurate control, high repeatability, consistent performance and superior output quality.

The KOH Etching Process
The KOH etching process is well understood and is a preferred method for creating silicon wafer nano structures for semiconductor manufacturing and in research facilities. The process delivers controlled and uniform results with high precision and it is relatively safe.

The silicon surface is masked to allow etching and cavity creation in specific areas according to the layout of the final semiconductor product. The etch rate can be controlled by varying the concentration of KOH and the bath temperature. KOH etching is also impacted by the following:

  • The lattice planes of the crystalline silicon
  • Boron doping of the silicon
  • The presence of atomic defects in the silicon crystal
  • Natural impurities

Orienting the lattice planes in a particular direction can influence and control the direction of the etching and the shape of the cavities created in the silicon. Similarly, boron doping can be used to stop etching in a particular direction. Together with the mask, these factors permit the creation of cavities of the required shapes and orientations. Defects in the silicon crystal or natural impurities may reduce the quality of the final product and can result in defective items.

Advantages of KOH Etching
KOH etching provides excellent results and is used extensively because of the following advantages:

  • Safe and easy to handle
  • Rapid etching
  • Excellent reproducibility
  • Low cost
  • High precision when process variables are tightly controlled

Modutek can supply equipment that builds on the listed advantages to deliver corresponding benefits to the customer.

Modutek’s KOH Etching Process Equipment
Modutek’s wet bench technology supports KOH processing, and Modutek examines each request in detail before building the equipment for a particular application. This includes the KOH processing tank, the recirculating system and the silicon wafer handling. Sizes, capacities and control characteristics are adjusted for the customer’s requirements.

The systems supplied by Modutek use the latest technology to provide high accuracy and excellent output quality. Etch rates can be controlled precisely and etch uniformity is guaranteed. Even long etch times, such as up to 3 days, can be handled reliably and safely.

Modutek’s KOH processing tanks are PFA Teflon with all-Teflon fluid paths. The tanks are manufactured onsite using advanced PFA sheet welding techniques designed to minimize impurities and unwanted by-products. The tanks are available as static or as recirculating baths.

The static baths can be ambient temperature baths or temperature controlled from 30 to 100 degrees centigrade. The recirculating temperature controlled baths feature heat-up rates of 2 to 3 degrees centigrade per minute and a temperature control accuracy of plus/minus 0.5 degrees centigrade. The available semi automatic cassette handling reduces costs and increases reliability.

In each case Modutek makes sure that the equipment supplied fits into the existing or a new installation and is compatible with any other wet processing systems. Modutek’s specialists work to ensure the supplied equipment satisfies the customer’s requirements and meets or exceeds performance expectations.

Wet Processing Systems for Solar Cell Manufacturing

Wet Processing Systems for Solar Cell ManufacturingSolar cell manufacturing facilities and research labs use wet processing equipment to etch and clean solar cell silicon wafers. Efficient removal of wafer saw damage, adding of texture, chemical polishing and cleaning of the wafers with reliable, safe wet processing systems is a key factor for increased facility productivity and high quality output. Modutek offers the latest wet bench and ozone cleaning technology to meet customer requirements either with standard systems or customized solutions.

Silicon Wafer Saw Damage Removal

Solar cell silicon wafers are cut from silicon bricks with wire saws, leaving a damaged surface with irregular crystal structure and a damaged crystal lattice. The wafers are placed in an etching bath that removes a thin layer of damaged crystal and leaves a smooth and uniform surface. Modutek wet processing equipment delivers high throughput with accurate controls and consistent results for this process.

Silicon Wafer Texturing

Silicon wafers used for solar cells absorb more light and convert light to electricity more efficiently when their front surface is etched with a microscopic texture. The texture reduces reflection of light from the solar cell surface and promotes internal reflection. For monocrystaline silicon, an etching bath removes small pyramid shapes from the surface of the silicon, leaving an even, consistent texture. For multi crystal silicon, the surface can be etched the same way, but the result is uneven and less effective due to the different orientations of the crystals. Alternative solutions with ion-etching and masks are available.

Chemical Polishing

After the front of the wafer is textured, the rear side remains comparatively rough. Such roughness can reduce the life span of the solar cell and impacts performance. By polishing the rear side of the cell and the edges in an etching bath, internal light reflection is improved and a higher efficiency cell can be manufactured.

Ozone Pre-Cleaning

The cutting of silicon wafers with a wire saw uses a slurry applied to the wires. The cut wafers are contaminated with the slurry and have to be cleaned before they can be etched, textured and polished. The Modutek Ozone Cleaning Process uses ozone dissolved in a mild acid bath to deliver high-performance cleaning at low cost.

The Modutek Ozone Cleaning Process reduces the use of expensive and environmentally harmful chemicals while improving throughput and producing wafer output with fewer defects. The equipment itself is less expensive than other cleaning solutions and there are lower costs due to reduced use of water and for disposal of waste.

Modutek Wet Processing Systems for the Solar Industry

Modutek has been providing wet processing equipment for semiconductor manufacturing for over 35 years and has the experience to examine customer applications and recommend the best solutions. For solar cell manufacturers, Modutek can offer the right equipment for cleaning, etching, polishing and texturing the silicon wafers and can make recommendations on the processes to be used.

In some cases it may make sense to combine saw damage removal with texturing or with polishing and different chemical baths may be appropriate for different customer needs. Modutek can advise customers which wet processing systems they need and can customize equipment if required. Modutek supplies wet processing systems and related equipment to solar cell manufacturers in the United States as well as around the world. Contact Modutek for a free quote or consultation to discuss which equipment to use for your application requirements.

Upgrading Used Semiconductor Manufacturing Equipment and Wet Benches

Upgrading Used Semiconductor Manufacturing Equipment and Wet BenchesSometimes it makes more sense to upgrade existing equipment than to buy complete new systems. Equipment may not be near the end of its useful life and new technology can often increase yield and output quality. Customers can address ongoing safety issues and reduce frequent unscheduled downtime. Upgrades can provide higher levels of automation and improved robotics can be installed.

When equipment breaks down, it may be an opportunity to replace key components while whole subsystems can be upgraded during scheduled maintenance to avoid additional downtime. By addressing known weaknesses in a production line, the overall reliability of operations can be increased. Upgrading wet bench stations and other semiconductor manufacturing equipment in this way can be a cost-effective means of improving productivity.

Specific Reasons for Upgrading Equipment

Retrofitting new components, upgrading existing equipment and repairing defective parts can often extend the life of your semiconductor manufacturing systems. Reasons for upgrading include the following:

  • Install improved technology to increase throughput
  • Upgrade components to obtain higher yield
  • Refurbish or replace equipment that is no longer supported
  • Save money by extending equipment life span
  • Accommodate larger wafers
  • Update the automatic and robotic systems and controls
  • Improve ventilation and safety
  • Upgrade electrical systems to the latest standards
  • Improve ergonomics and ease of operation
  • Improve chemical delivery system performance

Such upgrades depend on a supplier’s ability to evaluate a system’s specific requirements and implement a customized approach to install and repair components. Extensive experience with development and assembly of semiconductor fabrication equipment is a prerequisite for carrying out upgrades effectively.

Types of Upgrades Carried Out by Modutek

Modutek relies on their experience with in house development and manufacturing of wet bench and related equipment to carry out all types of upgrades, both on their own equipment and that of other manufacturers. Such upgrades can include:

  • Identifying and replacing failing parts
  • Replacing defective parts with new or retro-fitted components
  • Replacing obsolete components
  • Updating robotics, baths and wet etching components
  • Upgrading motion controls and software
  • Re-designing and improving systems within an existing footprint
  • Reconditioning existing systems to improve performance

Modutek can visit a customer’s site and perform system evaluations to develop possible upgrade, repair and retrofit scenarios. Customers can then decide how they want to proceed and Modutek can carry out the selected work.

Specific Benefits of Upgrading

Many upgrades have specific benefits associated with them and customers can rely on Modutek to carry out the work so that the expected advantages are realized. For example, upgrading controls is an effective way of improving performance. Customers can upgrade from manual or semi-automatic operation to semi-automatic or fully automatic systems to improve consistency and reduce operator errors. Upgraded controls can also reduce waste and ensure that chemical formulas are followed accurately.

Safety upgrades are often required and always reduce operator risk. Adding robotics can result in more accurate control and improved safety. When electrical systems are brought up to code, reliability often improves as well as making the systems safer. Adding ventilation, fire suppression, tank lids and fume control can improve operator comfort as well as increase safety.

Adding heaters, chillers and temperature controls can reduce process times and result in better performance. Level sensors give more accurate system feedback and adding pumps, valves and switches can result in better overall process control.

Modutek can determine whether such upgrades and retrofits make sense and then carry out the appropriate work. The company can evaluate the performance of its own older systems as well as semiconductor fabrication equipment from other manufacturers on a case by case basis that includes MEI, Amerimade, Micro Tech Process, JST Manufacturing and others. With its in house expertise, Modutek can reliably upgrade semiconductor manufacturing equipment to provide optimal performance and guarantee the results.