Improving Process Control with Fully Automated Wafer Fabrication Equipment

Improving Process Control with Fully Automated Wafer Fabrication EquipmentAn increasing number of silicon wafer fabrication applications, such as those with large size substrates or densely packed components, require tight process control. Accurate chemical dosage and precise process timing become critical for a high-quality output. Manual and semi-automatic controls depend on operator training and reliable operator execution of instructions, leaving open the possibility of human error and a variation in how process steps are carried out. Fully automated wet benches and chemical stations can improve process control accuracy and help with consistent execution. Software can help calculate process variables and ensure correct dosages. Full automation of the wafer fabrication process with the use of software for process control and robotics for wafer handling can result in better repeatability, reduced waste and improve production line performance.

Advantages of Modutek’s Fully Automated Wafer Fabrication Equipment

Modutek designs, develops and manufactures its wafer fabrication equipment in house to the highest quality standards. The SolidWorks Simulation Professional and SolidWorks Flow Simulation software are developed and supported in house by Modutek’s technical personnel. As a result, Modutek has the expertise to determine what is needed to meet the requirements of a specific customer’s application. It can supply standard wet bench chemical stations or customized equipment to exactly meet the needs of its customers, tailoring its equipment and software to fit any special process control requirements.

To satisfy customer requirements, Modutek can draw upon its complete line of wafer fabrication equipment. Its wet benches and chemical stations can handle both solvent and acid applications, and the equipment can process sizes up to 30 inches by 60 inches. Its software can run simulations, calculate chemical dosage and track chemical use. With its in-house expertise, Modutek can offer unparalleled customer support and comprehensive after sales service.

Benefits of Fully Automated Wafer Processing Equipment

Full automation means that the process is set up and can then run repeatedly in exactly the same way without requiring any operator input. Key factors for improved process control are accurate chemical dosage, precise timing of process steps, exact replication of the process sequence and full neutralization of chemical waste. Because operation of the automated program is transparent and recorded, technical personnel can optimize the individual steps to minimize chemical use and reduce waste. Process times can be adjusted to take into account special features of the application and results can be monitored for potential problems.

When the process automation is fully optimized, consumption of chemicals is reduced. Process output stays constant, the number of defective products is lower and the products are of consistently high quality. There are fewer spills and dosage errors while employee safety is higher. Compliance with environmental regulations in terms of chemical use and discharge is easier because chemical consumption is tracked at all times and the neutralization of discharges is ensured. The process environment is consistent and the optimized process can be repeated reliably.

As a result, wafer fabrication facilities that implement full automation experience lower costs due to reduced chemical use. Yield and throughput increase while output quality remains consistent and high. Production line performance and productivity improve and facility profitability can rise.

How Modutek Can Help

With over 35 years experience in wet bench process and wafer fabrication equipment, Modutek can evaluate a customer’s process needs and offer standard equipment or customized solutions as appropriate. Their engineers can work closely with each customer to identify what is required and ensure that the equipment works as expected. Modutek’s fully automated stations are an excellent choice for reliable and technologically advanced solutions to challenging wafer fabrication requirements. If you need highly reliable wafer fabrication equipment to support your semiconductor manufacturing process call Modutek for a free consultation at 866-803-1533 or email [email protected].

Modutek Provides Solvent Delivery Pump Station for Large Pharmaceutical Company

Modutek Provides Solvent Delivery Pump Station for Large Pharmaceutical CompanyWith over 35 years of experience in the semiconductor manufacturing industry, Modutek has the expertise to handle large projects and challenging applications. The most recent example is a solvent delivery pump supply for a large pharmaceutical company. Nine solvent pump cabinets are required to transfer solvents to centrally located distribution stations. The custom-built cabinets are subject to tight specifications and rigorous compliance with applicable standards.

Project Details

Modutek will supply nine solvent pumping cabinets, each containing two pneumatically operated pumps. The pumps will have pulse dampers and will be fitted with air-actuated ball valves on the inlets and discharge outlets of each pump. Pilot valves will control the supply of clean, dry air (CDA). A series of valves and monitoring systems controls and supervises the transfer of solvents to distribution points close to the process.

Each cabinet will have an ultrasonic leak detector housed in a one-inch pipe “T” at the lowest point in the cabinet. A drain On/Off selector switch will be mounted near the drain port on the outside of the cabinet, and a 4-20 ma pressure transmitter will be mounted on the outside of each cabinet so the local display can be read easily.

Pump Cabinet Operation

The pumps will be controlled by a Programmable Logic Controller (PLC) and will deliver up to four gallons per minute. Solvents handled include acetone, methanol, ethyl acetate, heptane, isopropyl acetate and methyl tert-butyl ether. The system is rated up to 200 degrees Fahrenheit, and the passivation of the stainless steel parts is per ASTM standards. The pressure drop can be controlled through the PLC and the installation must be FDA compliant.

When a request for a pump is received, the drain valve On function is disabled and the pilot valve supplying CDA to the pump opens. The pump inlet and discharge ball valves open allowing solvent to flow past the pressure transmitter to the process. If a leak is detected in the pipe “T,” the pilot valve and the corresponding ball valves close, stopping transfer of the solvent.

When the drain function is switched On, the pilot valves and pump inlet and discharge ball valves are disabled. The pneumatically operated drain valve opens and the solvent drains into a collection container outside the cabinets. Once draining is completed, the operator can close the drain valve and resume normal operation of the pumps.

During normal operation of one of the pumps, the 24 V DC 4-20 ma pressure transmitter displays pressure in the line from the pump to the process. The pressure range is 1 to 150 psi. The pressure reading is displayed on a local LCD display and is available for remote indication and for HMI or SCADA systems.

Partnering With Modutek

Modutek can help customers that have complex or wide-ranging chemical delivery system requirements. The company offers standard solutions from its complete chemical delivery system equipment line or it can design and manufacture custom solutions to meet the needs of specific applications. All of Modutek’s chemical delivery system equipment is engineered and manufactured in-house at the company’s San Jose facility. As a result, the company can rely on in-house expertise to build and service the required equipment.

Modutek’s chemical handling systems are built using the latest technology and the highest quality materials to achieve un-paralleled output quality at reduced overall cost. When chemical handling/delivery systems are precisely designed to match application requirements, waste is reduced, and the use of water and chemicals are minimized. There are fewer operator errors, and systems become safer and more productive. Choosing Modutek as a supplier can help improve production facility performance and increase profitability.

Why Quartz Baths Are Used in the Wafer Cleaning Process

Why Qartz Baths are Used in the Wafer Cleaning ProcessThe cleaning of silicon wafers during semiconductor manufacturing uses strong, corrosive chemicals to remove deposits from the surface of the silicon. Critical factors for effective cleaning are an absence of contamination in the chemical bath, the impervious nature of the container and a tight control of the bath temperature. Baths made from high purity quartz don’t react with chemicals used in semiconductor manufacturing and are inert as a source of contamination. Quartz conducts heat well so fast temperature rise and accurate control are possible. A high-quality quartz bath is an ideal container for the semiconductor wafer cleaning process.

How Quartz Baths Are Used

The semiconductor manufacturing process involves multiple steps, each of which may require cleaning of the silicon wafer before or after the production process segment. Highly corrosive chemicals such as sulfuric acid, hydrogen chloride or hydrogen peroxide are used to remove materials such as organic residue from the surface of the wafers in preparation for manufacturing steps such as etching or diffusion. Effective cleaning is a critical factor in the success of semiconductor manufacturing because impurities or contaminating particles left on a wafer can lead to defective products or products of inferior quality.

During the cleaning process, the silicon wafers are immersed in chemicals within the quartz bath. Depending on the cleaning process, the baths may be heated, kept at a given temperature for a defined time period and chemicals may be re-circulated. For example, in RCA clean, wafers are first immersed in a mixture of ammonium hydroxide and hydrogen peroxide. These chemicals remove organic contaminants and particles from the surface of the silicon wafers. After rinsing and drying, the wafers are immersed in a mixture of hydrochloric acid and hydrogen peroxide. In this step metallic contaminants and particles are removed. The wafers are then cleaned for subsequent processing steps.

If particles remain on the wafers or if impurities are introduced during the cleaning process, manufacturing steps such as diffusion will be affected. With microscopic semiconductor structures, even tiny particles can obstruct an electrical connection or affect electrical characteristics. The semiconductor product may then fail prematurely or not work properly. When the quartz container is eliminated as a source of contamination, the focus is on the wafer cleaning process itself and its effectiveness in removing contaminants and particles.

How Quartz Baths Facilitate Reliable Cleaning

Quartz baths can meet all the criteria for effective cleaning of silicon wafers but they have to be designed well and constructed with top quality materials. Modutek series QFa re-circulating baths are made with semiconductor grade flame polished quartz to reduce the possibility of contamination. They feature quick, even heating and are available in a variety of standard as well as custom sizes. Operation is reliable and safe with excellent wafer cleaning performance and high quality output.

Operating characteristics include a temperature range of 30 to 180 degrees centigrade and the tanks can heat the bath at a rate of 2 degrees centigrade per minute. Temperature control is accurate within plus/minus 1 degree centigrade and heating is even through the bath. Standard tank sizes range from 7.75 inches to 21.5 inches a side with a depth of up to 14.5 inches. Custom sizes are available.

Modutek uses its experience of over 30 years designing quartz baths to deliver the highest quality baths with excellent cleaning performance. Modutek baths feature safe operation, reliable output and a low cost of ownership. The company can advise customers how best to meet their semiconductor wafer cleaning needs and can make specific proposals for solutions based on the company’s complete range of wet bench processing equipment.

Why Quartz Baths Are Used in the Wafer Cleaning Process

Why Quartz Baths Are Used in the Wafer Cleaning ProcessThe cleaning of silicon wafers during semiconductor manufacturing uses strong, corrosive chemicals to remove deposits from the surface of the silicon. Critical factors for effective cleaning are an absence of contamination in the chemical bath, the impervious nature of the container and a tight control of the bath temperature. Baths made from high purity quartz don’t react with chemicals used in semiconductor manufacturing and are inert as a source of contamination. Quartz conducts heat well so fast temperature rise and accurate control are possible. A high-quality quartz bath is an ideal container for the semiconductor wafer cleaning process.

How Quartz Baths Are Used

The semiconductor manufacturing process involves multiple steps, each of which may require cleaning of the silicon wafer before or after the production process segment. Highly corrosive chemicals such as sulfuric acid, hydrogen chloride or hydrogen peroxide are used to remove materials such as organic residue from the surface of the wafers in preparation for manufacturing steps such as etching or diffusion. Effective cleaning is a critical factor in the success of semiconductor manufacturing because impurities or contaminating particles left on a wafer can lead to defective products or products of inferior quality.

During the cleaning process, the silicon wafers are immersed in chemicals within the quartz bath. Depending on the cleaning process, the baths may be heated, kept at a given temperature for a defined time period and chemicals may be re-circulated. For example, in RCA clean, wafers are first immersed in a mixture of ammonium hydroxide and hydrogen peroxide. These chemicals remove organic contaminants and particles from the surface of the silicon wafers. After rinsing and drying, the wafers are immersed in a mixture of hydrochloric acid and hydrogen peroxide. In this step metallic contaminants and particles are removed. The wafers are then cleaned for subsequent processing steps.

If particles remain on the wafers or if impurities are introduced during the cleaning process, manufacturing steps such as diffusion will be affected. With microscopic semiconductor structures, even tiny particles can obstruct an electrical connection or affect electrical characteristics. The semiconductor product may then fail prematurely or not work properly. When the quartz container is eliminated as a source of contamination, the focus is on the wafer cleaning process itself and its effectiveness in removing contaminants and particles.

How Quartz Baths Facilitate Reliable Cleaning

Quartz baths can meet all the criteria for effective cleaning of silicon wafers but they have to be designed well and constructed with top quality materials. Modutek series QFa re-circulating baths are made with semiconductor grade flame polished quartz to reduce the possibility of contamination. They feature quick, even heating and are available in a variety of standard as well as custom sizes. Operation is reliable and safe with excellent wafer cleaning performance and high quality output.

Operating characteristics include a temperature range of 30 to 180 degrees centigrade and the tanks can heat the bath at a rate of 2 degrees centigrade per minute. Temperature control is accurate within plus/minus 1 degree centigrade and heating is even through the bath. Standard tank sizes range from 7.75 inches to 21.5 inches a side with a depth of up to 14.5 inches. Custom sizes are available.

Modutek uses its experience of over 30 years designing quartz baths to deliver the highest quality baths with excellent cleaning performance. Modutek baths feature safe operation, reliable output and a low cost of ownership. The company can advise customers how best to meet their semiconductor wafer cleaning needs and can make specific proposals for solutions based on the company’s complete range of wet bench processing equipment.

Selecting Equipment for the KOH Wafer Etching Process

Selecting Equipment for the KOH Wafer Etching ProcessKOH etching is increasingly used for creating microscopic structures in silicon. The wafer etching process uses a 20 to 30 percent solution of potassium hydroxide to create cavities in the unmasked parts of a silicon wafer. KOH etching is comparatively safe and etching can be tightly controlled through regulation of the bath temperature and doping of the silicon. Semiconductor fabrication facilities favor this etching method because of its high precision, good repeatability and cost effectiveness.

How It Works

The silicon wafer is masked with a material impervious to KOH, usually silicon dioxide or silicon nitride. The mask is based on the layout of the structures and circuits of the final semiconductor product and determines where cavities will be etched. The silicon wafers are immersed in the KOH solution and the temperature is controlled to give the desired etch rate.

KOH etching is extremely sensitive to temperature variations at temperatures above 60 degrees centigrade, with the etch rate in microns per hour approximately doubling for every ten degree rise in temperature. A typical rate is 1 micron per minute for a bath at 80 degrees centigrade. Accurate control of the temperature is a key factor in precise etching results.

While varying the temperature can control the etch rate, the orientation of the crystal planes in the silicon and doping of the silicon with boron also influence the rate and direction of the etch. The anisotropic nature of the silicon crystal can be used to create slopes and shapes along the crystal planes and the etch can be stopped in specific locations with boron doping. This way KOH etching can create complex shapes and circuit paths for semiconductor products.

Modutek KOH Bath Equipment

Modutek supports KOH etching as one of its wafer etching process options in the company’s line of wet bench process equipment. The TFa and TT series Teflon heated tanks are ideal for the requirements of KOH etching. The tanks are available for standard carrier sizes for single or double capacity and Modutek can also build custom sizes if needed. The modular nature of the tanks means they can easily be integrated in any new or existing wet etching station.

The TFa series high temperature overflow tanks and the TT series static tanks are both PFA Teflon tanks with an all-Teflon fluid path. Heating can be inline or immersion heating in the overflow weir. The operating temperature range is from 30 to 100 degrees centigrade and the tanks can heat up at the rate of 2 to 3 degrees centigrade per minute. Temperature control accuracy is plus/minus 0.5 degrees centigrade and liquid levels and high temperatures are monitored. The high precision temperature control and the rapid heating rate ensure that heating is uniform throughout the bath.

Additional features and specifications of the Modutek KOH etching tanks include 360 degree overflow filtration through serration overflow, an optional condensing Teflon refluxor with Teflon cooling coils, a pneumatically actuated auto cover, an aspirator valve system and a Teflon gravity drain. An RS232 interface, temperature controllers and remote operation timer switches complete the remote operation capabilities.

Modutek can help customers considering KOH etching in their selection of the appropriate systems. The company has a complete range of wet bench process equipment, chemical handling systems and equipment repair capabilities. In addition to their standard lines, Modutek can customize components to meet the specific needs of their customers. Experienced company personnel can work with customers to design optimal configurations and layouts for their clean room facilities. The KOH etching tanks are the ideal solution for semiconductor fabricators that need to etch microstructures in silicon wafers.

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.