How the Silicon Nitride Wet Etching Process is Improved by Modutek

Silicon nitride is used as a mask when etching silicon wafers during the semiconductor manufacturing process. Before the silicon wafer can be processed further, the silicon nitride has to be removed. A solution of phosphoric acid and de-ionized water etches the silicon nitride while leaving the wafer unaffected. As a result, the silicon nitride is stripped from the wafer surface and a clean wafer is left for further fabrication steps.

To optimize the silicon nitride wet etching process, the phosphoric acid solution is kept at a high temperature. This means some of the de-ionized water boils off as steam and has to be replaced. Adding water to phosphoric acid can be extremely dangerous and can result in an explosion. In addition, keeping the temperature of the solution constant is important for accurate control of the stripping process. Modutek has improved both the safety and the control of the nitride wet etching process with its Nb series silicon nitride wet etching baths.

How the Process Works

A solution of 85 percent phosphoric acid and 15 percent de-ionized water is heated to a boil at about 160 degrees centigrade. Some of the water boils off as steam and part of the steam is condensed and placed back in the solution. Some steam escapes and de-ionized water has to be added periodically. The solution is kept at the boiling point by a heater and the process temperature can be tightly controlled. With the Modutek system, nitride etch is uniform and there are no “bumps” in the chemical concentration or temperature.

How Modutek Controls the Etching Process Safely and Accurately

The two challenges faced when operating a boiling phosphoric acid bath is the safe replacement of the de-ionized water lost to steam and an accurate control of the process. If water is added to the solution too quickly, the solution may stop boiling and a film of water can accumulate on top of the viscous acid. If the water of the film then suddenly mixes with the acid, a strong reaction can occur, and an explosion is possible. Adding water in this way also makes accurate control of the process difficult.

In the Modutek system, the heater that boils the solution is always switched on. The solution is always heated up to the boiling point and further heating only increases the boiling rate but not the temperature. This control strategy results in a clearly defined temperature for the boiling solution, which will always be at its boiling point.

The boiling point of a phosphoric acid and water solution varies with the concentration, increasing as the solution loses water to steam. A thermocouple in the bath senses the increasing temperature and gives the signal to add water. De-ionized water is slowly added to the boiling solution. Because the acid is boiling rapidly, the small amounts of water are immediately mixed in and don’t form a surface film. Adding water in this way is safe and controlling the process by monitoring the concentration through the temperature rise is accurate.

Additional Safety Features

Since the silicon nitride wet etching process depends on keeping the solution at the boiling point, additional safety interlocks in Modutek’s etching baths are in place to insure no water is added if the solution is not boiling. A thermocouple above the solution senses the presence of hot steam and shuts off the water valve if steam is not present. To ensure the solution does not overheat, another thermocouple switches off the heaters when the temperature of the solution reaches 170 degrees centigrade. With its advanced control system and the additional safety interlocks, Modutek has improved the silicon nitride wet etching process with better control, accuracy and increased safety.

 

How the KOH Etching Process is Improved Using Modutek’s Teflon Tanks

Among the different approaches available to foundries that create intricate integrated circuitry on semiconductor chips, etching with potassium hydroxide (KOH) is frequently preferred for the error-free mass-production that it allows.

The improvement in precision that the KOH etching process brings to semiconductor fabrication is attributable in large part to the use of deionized water. When employed with high alkalinity in excess of pH 12, this process can be thermally adjusted for precise degrees of etching.

How does the use of potassium hydroxide improve the semiconductor etching process?

While dry semiconductor etching processes do exist, they tend to present challenges in process control. Semiconductor wafers etched in this way tend to suffer from quality control issues. Dry etching processes can be difficult to build and run, as well — toxic and explosive chemicals often seen as byproducts, after all.

Greater precision

Etching with potassium hydroxide offers greater precision, and lends itself to improved control, as well.

The fluids employed in the KOH etching process are stored in tanks built into the equipment. One of the most cost-effective and meaningful choices to make in KOH etching processes: to place Teflon tanks within the etching equipment in order to hold the fluids employed. Teflon tanks can make the KOH etching process safer than other options available.

It is possible to structure the KOH etching process in a way to easily create repeat manufacturing projects, as well. When such projects come in from different clients, fabrication units can focus their strengths on setting up the equipment, worrying as little as possible about safety or reliability.

Opting for fewer contaminants and greater cleanliness

Customization is one of the greatest most significant improvements that Modutek brings to the KOH etching equipment business — one where generic, mass-produced Teflon tanks are the norm. Modutek’s Teflon tanks are especially capable of bringing impurity quantities to levels that are impressively low. The result is greater reliability and consistency over an extended period of time.

Greater control

Modutek’s Teflon tanks come with highly customizable temperature settings. Temperature control is achieved either through in-line heating and cooling equipment installed, or through immersion in liquid tanks. It is precisely varied anywhere between 30°C to 100°C. Temperature changes dialed up our achieved at a fast rate of 2°C a minute, on average (although tank size does affect response rates).

Modutek brings customization to the table

Modutek designs Teflon tanks for the specific needs of each client installation. Whether a fabrication plant requires temperature controlled recirculating baths for their KOH etching processes or temperature controlled static baths, Modutek’s Teflon tanks deliver both freedom from water loss and freedom from concentration deficiency.

From dual heating Teflon tanks for fast and consistent water-based etching, to the installation of drains and valves that enable rapid cleanup, high-tech remote data interfaces, controllers and timers, Modutek’s clients have their choice of every advance in KOH etching.

 

How to Improve Your Silicon Wet Etching Process

Semiconductor research labs and fabrication facilities employ high-precision silicon wet etching processes that are capable of delivering quality product in a consistent way. This is no mean feat: the microscopic structures etched on semiconductor wafers require processes that meet microscopic tolerances while reducing the minutest of impurities. Fabs are always on the lookout for improvements to make in these processes; the aim is to minimize the number of errors made during each of several processes. Results depend on constant efforts in the area of identifying the best etching processes, and utilizing the best equipment.

The Wafer Etching Process

The process of etching micro-circuitry on silicon wafers requires a complex multi-layered fabrication approach. It usually requires multiple cleaning, masking, and etching processes that involve the precise deposition of metal traces and components. At different stages along the way, these processes require the use of chemical baths of various kinds, each aimed at achieving different, specific results. At the end of one of these precisely designed processes, silicon wafers with traces, electrical connections and electronic components, all etched on a microscopic scale, emerge ready for market.

There are various requirements for an error-free process — precise control over the speed at which etching is done, and the ability to achieve extreme levels of cleanliness in the work areas in which etching is done, are two primary requirements. There are many others, as well.

Silicon nitride: Silicon nitride is applied to mask parts of wafers during the phosphoric acid etching process. Achieving greater precision in this process delivers superior results. In general, fabs do much better with the fabrication process when they possess over on-the-fly control over acid concentration and temperature.

Piranha etching: At semiconductor fabs, piranha etching is done using a mixture of piranha solution — a blend of hydrogen peroxide and sulfuric acid. Chemical baths need to be carefully controlled to supply the right chemical mix at the right time.

Potassium hydroxide: The etching process requires the use of potassium hydroxide solution in the creation of microscopic structures on semiconductor wafers. Achieving precise and error-free etches requires an ability to closely control the concentration of the solution, the temperature, the orientation of the silicon crystal and silicon purity. These variables can change during the etch process, and error-free results requires the ability to respond by speeding up or slowing down etch rate.

Buffered oxide etch: This is a process that employs hydrofluoric acid in addition to a buffering agent in order to etch fine masking films of silicon dioxide or silicon nitride. When correctly controlled, the process delivers a consistent and repeatable result that works with photoresist.

When it comes to improved silicon etching performance, the key to high-quality results is to utilize processing equipment from a vendor with proven experience and support. Modutek answers this requirement with 35 years in the field. Not only is Modutek able to supply the equipment, they are able to advise clients on the customizations needed to meet their requirements.

Choosing Equipment with the Right Features for Each Stage of the Wafer Etching Process

Modutek’s silicon wet etching equipment comes with some of the most advanced features on the market today:

Flow control and filtration control: Modutek’s precision acid filters are effective down to the 0.2 µm range and are able to work continuously to enable reuse of acid. This provides considerable savings in acid consumption.

Precision control of temperature: An ability to precisely control the temperature of an etching bath can result in lower error rates and reliable output. In any process, Modutek’s equipment comes with the ability to control temperatures to within 1 degree of required settings.

Precision tech design: Potassium hydroxide requires the use of Teflon tanks; piranha solution requires quartz. Modutek designs these tanks in a wide variety of configurations and sizes.

Modutek is dedicated to helping clients find ways to improve the efficiency of their silicon wet etching processes, improve productivity and output quality. To this end, Modutek’s offers extensive consultation and equipment customization needed to meet each customer’s requirements.

Etching Silicon Wafers Without Using Hydrofluoric Acid

Etching Silicon Wafers Without Hydrofluoric AcidHydrogen fluoride is an excellent etching chemical for silicon wafer fabrication, etching rapidly to remove silicon oxide, for example after an initial RCA clean. While highly effective, hydrofluoric acid is extremely dangerous. Its vapor can cause death and it is toxic enough that even a small area of skin exposed to the chemical can cause cardiac arrest. As a result, storage and handling is difficult and disposal problematic. Safety and environmental considerations have resulted in a search for alternatives. Depending on the silicon wet etching application, other chemicals may be suitable for replacing hydrofluoric acid and Modutek can help customers make the change by recommending equipment that supports alternative chemical processes.

Why Hydrofluoric Acid is Especially Dangerous

Hydrofluoric acid is extremely toxic and penetrates the skin to cause secondary effects that require medical attention. Its vapor can cause lungs to fill up with liquid and exposure to even small amounts can cause death. Neutralization and disposal is difficult and any mistakes run the risk of severe environmental contamination. Given the dangers, silicon fabrication facility owners, managers and process engineers are looking for alternative process chemicals.

While hydrofluoric acid is dangerous as a corrosive chemical, its added danger comes from its absorption into the body. It affects the nerves at sites where the skin has been exposed to the acid and victims may initially feel little pain as a result, often delaying treatment. At the same time, hydrofluoric acid can penetrate deep into the body and attack underlying tissue and bones, causing lasting damage. It also disrupts the calcium chemistry of the blood, eventually leading to cardiac arrest. Exposure of as little as 25 square inches of skin can result in deep burns that are slow to heal and in death if medical treatment is delayed.

Bare skin and the eyes are the most common areas of exposure. Treatment starts with extensive rinsing, for about 15 minutes, of the exposure site. Repeated application of calcium gluconate gel helps mitigate the effect on blood calcium. Anyone with more than four square inches of skin exposed should be admitted to hospital for monitoring of blood chemistry. Normal safety measures to avoid contact with hydrofluoric acid are to cover all skin and wear eye protection.

Hydrofluoric acid is hazardous waste and its discharge is tightly regulated. The acid must first be neutralized and then discharge limits on fluoride and metals must be observed. A complete neutralization process often starts with adding a basic solution to the acid and then precipitating out other materials until they fall within discharge limits. After discharge, the resulting sludge represents an additional waste problem. While other chemicals may be subject to similar discharge procedures, hydrofluoric acid represents an additional risk if neutralization is not carried out properly.

Possible Alternative Etching Solutions

Depending on the particular silicon wet etching application, other etchants may be substituted for hydrofluoric acid. Potassium hydroxide (KOH) is a safer chemical and can be used for etching in many applications.  Tetramethylammonium hydroxide (TMAH) and nitride etch are other possible alternatives that may be used.

Modutek can help facilitate a switch from hydrofluoric acid where possible. The company has over 35 years experience with silicon wafer fabrication equipment and has the in house expertise to advise customers about possible alternatives.

In addition to analyzing customer process needs and making recommendations, Modutek can supply the equipment required from their complete line of wet bench and chemical delivery stations. Modutek’s equipment, while able to handle hydrofluoric acid, is also designed to work with other chemical processes that don’t use it. Modutek can offer standard or customized components such as Teflon tanks or quartz baths to help customers wishing to use other chemicals where they can. Contact Modutek for a free consultation and quote on selecting the right equipment to support the silicon wet etching process for your application.

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.

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.

Selecting the Right Equipment for Your Silicon Wet Etching Application

Selecting the Right Equipment for Your Silicon Wet Etching ApplicationSemiconductor manufacturing involves many process steps that require fabrication facilities to utilize the right processing equipment. Fabrication facilities need to choose a semiconductor equipment supplier that can provide a broad range of reliable products to support their applications, and also insure that the equipment to meets all requirements. Modutek has extensive experience and expertise in providing high quality equipment and a record of supplying reliable products for all silicon wet etching applications.  Below several products are discussed along with the specific wet etching applications that they support.

Quartz Baths
Quartz baths support a variety of etching, cleaning and stripping processes including SC1 cleaning, RCA clean and SPM clean. The Modutek bath designs have evolved over 30 years to become the quality standard in the industry. They are made of semiconductor grade, flame polished quartz and come in a range of sizes from inner lengths of 7.75 inches to 21.5 inches and heater power from 2 to 6 kW. The designs emphasize safety, reliability and cost of ownership.

Sub-ambient Systems
Modutek’s sub-ambient filtered etch baths are specifically designed for BOE (buffered oxide etch) and positive resist develop applications. They feature continuous filtration in the 10 to 0.2 micron range, reduced acid consumption and a low cost of ownership. They are made of natural polypropylene and polyvinyldilene fluoride (P.V.D.F), offer a 10 to 60 degree centigrade range of operation and plus/minus 1 degree temperature control. A range of options lets customers match the system to their requirements.

Temperature Controlled Circulators
The Modutek RCe Series of Temperature Controlled Recirculators are suitable for etching, plating and developing applications and constant temperature baths. The units feature a compact design and stainless steel fluid paths for a high level of safety and reliability. The standard heating capacity is 1500 W while cooling capacity is one quarter horse power. Other heating and cooling sizes are available.

Teflon Tanks
Teflon tanks by Modutek feature a modular design that is easy to integrate into new silicon wet etching stations or incorporate into existing stations. Available configurations are temperature controlled recirculating baths, temperature controlled static baths and Teflon ambient baths. Heat sources can be Teflon inline heating or immersion heating in the overflow weir. The tanks are available in standard carrier sizes for single or double capacity and they support KOH Etching and TMAH applications.

Nitride Etch Baths
Modutek nitride etch baths are designed for unparalleled process control with an emphasis on safe operation. Modutek has designed a two-tier control system that monitors the temperature while maintaining the acid to water ratio by adding de-ionized water as required. The resulting chemical boiling achieves tight temperature control and avoids bumping. A remote metering system facilitates installation in new or existing stations.

Quick Dump Rinsers
The quick dump rinsers offered by Modutek provide efficient process rinsing without particle entrapment and reduced use of de-ionized water. They provide consistent rinsing with bottom filling, well-located D.I water spray nozzles and N2 agitation. A bottom filling option that creates a vortex agitation in the rinse tank is optional.

Solvent Baths
Modutek solvent baths are electropolished stainless steel tanks suitable for all solvent applications including IPA, acetone and resist strippers. The baths meet Class 1 Div 1 Group D requirements over an operating range of 30 to 100 degrees centigrade and the heat up rate is up to 2 degrees centigrade per minute, depending on the system size. Bath design is flexible and Modutek can help customers ensure the bath selected fits into their new or existing installation.

Modutek has over 35 years of continuous operating experience in developing and supplying silicon wet etching equipment. This experience results in a flexible approach and an unmatched range of semiconductor manufacturing equipment options. Modutek can supply the right equipment for a customer’s particular application and can help ensure that the selected equipment meets the customer’s needs. Call for a free quote and recommendations on using the right equipment for your silicon wet etching application.

How Quartz Baths Are Used in a Manufacturing Process

How Quartz Baths Are Used in a Manufacturing ProcessThe manufacture of semiconductor components requires the cleaning, stripping and etching of semiconductor wafers using corrosive chemicals in a tightly controlled environment. Two important factors for achieving improved yields of functional components are keeping the bath free from contaminants and accurately controlling the temperature. High quality quartz baths fulfill these requirements with a tank material that is impervious to the chemicals used in the baths and that facilitates fast even heating by conducting heat efficiently. A well-designed quartz bath is the most effective solution for processing semiconductor wafers in chemicals such as sulfuric or hydrochloric acids, even at elevated temperatures.

Important Characteristics of Quartz Baths

To process semiconductor wafers effectively, quartz baths must be well designed and be made of quality materials. To avoid introducing unwanted impurities into the process the bath must be made of quartz of the highest purity. It must be available in a variety of sizes and heat up rapidly, featuring tight temperature control. Operation must be safe and reliable, ideally based on extensive experience in the design and supply of these products.

Modutek Recirculating Quartz Baths

The Modutek Series QFa quartz baths are high temperature recirculating units manufactured to the highest quality standards. Modutek has over thirty years experience in designing quartz baths and the company uses the expertise acquired with this evolution to offer the best in the industry. Key qualities resulting from this evolutionary process are safety, reliability and low cost of ownership.

For its recirculating quartz baths, Modutek uses semiconductor grade flame polished quartz to keep potential contamination to a minimum. The baths feature fast, even heating and a seamless, sloped flanged design that helps ensure safe operation. Temperatures in the range of 30 to 180 degrees C. can be controlled to plus/minus 1 degree C. and the heat-up rate can be up to 2 degrees C. per minute. Bath sizes range from 7.75 x 7.75 x 9 inches to 21.50 x 11.50 x 10.50 and 17.87 x 10.75 x 14.50 inches while custom sizes are available as well.

Modutek Constant Temperature Quartz Baths

With many of the same quality and operating features as the QFa models, the quartz baths of Modutek Qa series meet the same goals of high safety and reliability combined with a low cost. The process vessel is made of internally flame polished virgin fused quartz, boron-free, and the baths have the same accurate temperature control of 1 degree C. with a heat-up rate of 2 degrees C. per minute. Options include a magnetic stirrer, a quartz bubbler and remote operation timer switches and available sizes are similar to those for the recirculating baths. Modutek quartz baths can be used with confidence to improve semiconductor processing performance.

If you need help selecting quartz baths to use with your manufacturing process, contact Modutek at 866-803-1533 or email [email protected].

How Technology Manufacturers Use Chemical Delivery Systems

How-Chemical-Delivery-Systems-are-Used-by-Technology-Manufacturers

Technology manufacturing requires the safe handling of chemicals as well as their delivery in accurate amounts. Corrosive chemicals are used for etching, cleaning and plating materials such as silicon chips, metal parts, solar system components and printed circuit boards. The chemicals have to be stored securely, delivered to the process in precise amounts, and neutralized before disposal. Automated chemical delivery systems reduce waste and operator error while allowing the supply of defined amounts of each chemical with a high degree of precision.

Technology manufacturers use these systems to supply chemicals to wet processing equipment. Acids are used to etch away layers of material on wafers of silicon, printed circuit boards or other substrates. Sections of the layers to be etched are covered in protective material and are not removed by the etching. In this way microscopic structures and conducting paths can be created. The requirements for chemical delivery systems depend on the application of the wet processing equipment and on the chemicals to be used.

The key to supplying effective chemical delivery systems is a flexible approach combined with the ability to develop systems customized to meet the needs of the manufacturer. Companies that manufacture silicon wafers have different requirements from those that manufacture micro-electro-mechanical systems, hard disk drives or solar cells. The cleaning and etching processes of different technology manufacturers use various chemicals and widely varying amounts and process control strategies. Their chemical delivery systems must be resistant to corrosion, be safe to operate, allow the storage of large amounts of chemicals and include flexible software to control distribution. An equipment supplier has to have a good understanding of the processes involved so that they can standardize the parts of the system that can remain the same while developing custom solutions to match the needs of each technology manufacturer.

Modutek specializes in designing and manufacturing systems that provide outstanding performance and reliability with the ability to be highly customizable. The systems incorporate user-friendly features that promote safe and cost-effective operation. In a typical custom application, water use, and the number of defective parts produced is reduced while consistency of results increases.

Modutek’s chemical delivery systems feature all Teflon fluid paths, double containment cabinet construction, leak detection and chemical level sensing. Double wall plumbing and system data logging are available. Chemical storage can be in large tote chemical containers or 55-gallon drums close to the wet process station. Manufacturers that use different chemicals can improve throughput because the Modutek’s systems are designed for quick chemical change.

The software that automates a chemical delivery system is a key factor in the system’s flexibility and Modutek can customize the software to meet the needs of the technology manufacturer. Typically a touch screen shows error messages on start-up and then displays a flow diagram showing the status of key components such as metering pumps, valves and level switches. Since these may be different for particular customized applications, the software must be easily adaptable. All the software for Modutek’s chemical delivery systems is written in house. This means that Modutek has the in house expertise and capability to make changes in the software as needed and can provide excellent technical support without having to rely on exterior sources.

The Modutek chemical delivery systems are suitable for any technology manufacturer application. They are specifically designed for easy customization and provide reliable, cost-effective operation. For additional information about Modutek’s Chemical Delivery Systems or related products call 866-803-1533 or email [email protected]