How Quick Dump Rinsers Improve Silicon Wet Etching Process

Quick dump rinsers provide fast and effective rinsing of silicon wafers from chemicals and particles. During semiconductor fabrication silicon wafers are etched with chemicals and particles, which have to be rinsed off to prevent continued etching.

Modutek's quick dump rinser uses de-ionized water to wash away all traces of chemicals while introducing no new particle contamination source. It uses state-of-the-art engineering techniques that allow it to reduce de-ionized water consumption while featuring a short rinsing time and particle reduction. The large trap door and the contoured rinsing vessel shorten dump times and promote laminar flow to rinse away contaminants. The machined dump door doesn't have any seals or gaskets that could entrap particles, and the smooth polypropylene construction of the tank ensures that it is not a source of new particle contamination.

Once the silicon wafers are placed in the rinser, de-ionized water jets rinse the chemicals from the wafer surfaces. The tank fills, bringing the rinsed contaminants to the surface where they leave the tank through the overflow weir. A nitrogen bubbler produces gas bubbles that rise through the water and remove additional particles and contaminants. At the final stage of the rinse cycle, the trap door at the bottom of the tank opens to drain the water.

The entire rinsing process is fast and thorough without introducing new contamination. The use of Modutek's quick dump rinsers can improve production and output quality. When quick dump rinsers work rapidly, effectively removing chemicals, particles, and contaminants leads to an increase of throughput and reduced chances of product rejection.

Rinsing is required after most of the wet process production steps, and any time saved with a quick dump rinser is multiplied by the number of times rinsing takes place in the semiconductor production process. Modutek's quick dump rinser provides these benefits by addressing overall semiconductor manufacturing requirements.

Modutek's quick dump rinsers provide additional benefits, such as reduced costs and faster production line operation. Reduced de-ionized water lowers costs, and an optional reclaim system can result in extra savings. Besides quick dump rinsers, Modutek also supports customers with full line of standard or customized silicon wet etching equipment.

For more details read the complete article, How Quick Dump Rinsers Improve Silicon Wet Etching Process. If you have questions, or would like to set up a free consultation, call 866-803-1533 or email modutek@modutek.com.

How Chemical Carts Support Chemical Disposal

 

Chemical disposal is often associated with adhering to increasing local regulatory compliance. The solution is to either remove used chemicals for off-site disposal or use dedicated equipment for disposal according to official guidelines to address these difficulties.

 

Chemical carts remove chemicals quickly and safely. They can be rolled over to process stations and can pump used chemicals to a container on the cart. The used chemicals can then be turned over to a disposal company or neutralized and treated at the onsite facility. The manufacturing process can continue with a fresh batch of chemicals while documentation and handling of the used chemicals can be carried out according to local regulations.

 

Once the chemicals for a process step has been used, they have to be drained from the process tank so that the next process batch can begin. The use of chemical handling equipment, such as pump carts, provides a flexible solution that allows operators to remove used chemicals from the process tanks for different process steps.

 

The operator can roll the chemical pump cart to the tank that holds the used chemicals and use the suction wand to pump the chemicals out of the process tank. The used chemicals are pumped into a dedicated storage tank on the chemical pump cart; after that, the chemical cart can be rolled out to a designated disposal area.

 

Whether the company has chemical neutralization and disposal in-house or not, the chemicals can be transferred to a disposal system or turned over to an external chemical specialist. Either way, the company must prepare documentation for handling chemicals according to local laws and regulations before proceeding to the final disposal.

 

Modutek's chemical pump carts are compact and easy to roll out. They are built with white polypropylene and can be moved with swivel casters (with brakes) and have individual suction and discharge tubes. Pumping is with a 3/8th-inch pneumatic pump. The five-gallon chemical tank features a double containment system and is DOT-approved. For additional safety, the cart has a high-level sensor, which is interlocked with the pump. The plumbing is all Teflon, and each cart can handle multiple applications. 

 

Several options that can be included in the tank include chemical carts delivered in a stainless-steel design for solvent applications; a pressure interlock safety switch; a large capacity tank; a double dump design, among others. Customers can decide on any of these options to meet specific requirements.

Learn more by reading the complete article How Chemical Carts Support Chemical Disposal as well as Modutek’s complete line of chemical handling equipment. To schedule a free consultation or quote, contact Modutek at modutek@modutek.com or call 866-803-1533.

How Customized Equipment Improves Silicon Wafer Processing

Because semiconductor manufacturing consists of a large number of steps, silicon wafer processing often includes unique requirements. While standard equipment may be suitable to some extent, using custom equipment that is adapted to specific processes can usually improve production line performance.

Customization of a semiconductor manufacturing equipment can impact how well the silicon wafer processing equipment works in the following ways:

1) Physical customization of wet processing equipment

Semiconductor manufacturing equipment often has to fit into a defined space or retrofitted into an existing production line. In either case, the dimensions have to be customized to fit the available space. Modutek can build processing stations and tanks with special dimensions to fit and arrange components for less length or less depth as required.

2) Customized software for special calculations

Modutek's SolidWorks Flow Simulation and Simulation Professional software allows customers to calculate chemical dosages and track chemical usage accurately. Custom installations that support unique process requirements may require special calculations and the software can be adapted to track chemical usage. Since Modutek writes and supports their own software, any special requirements can be accommodated by adapting the program code.

3) Automation with customized characteristics

Modutek's standard wet processing equipment is available in fully automated, semi-automated, and manual versions, but customers may require some automated functions while other functions remain manual or semi-automatic. Manual controls are ideal for prototypes that need to define basic process parameters. The process is then optimized in semi-automatic operation while eventually running in fully automatic mode when in full production.

4) Customized process components and subsystems

 Process components and subsystems may include chemical delivery, baths, or tanks, wafer handling, and wafer drying. Modutek can integrate part of all of these functions into a single system or use separate units in a customized configuration. With the company’s expertise and experience as a leading wet bench manufacturer, Modutek can design customized configurations that support the required wet process functions and parameters required by a customer.

Modutek has a complete line of standard wet process stations, that are all designed and built in house. By working closely with customers Modutek ensures that any system customizations will meet the special process requirements that a customer may have.

For more details read the complete article, “How Customized Equipment Improves Silicon Wafer Processing”. Contact Modutek at 866-803-1533 or email modutek@modutek.com for a free consultation to answer any questions you have about your specific process requirements.

How High Temperature Quartz Tanks Improve Silicon Wafer Processing

The silicon wafer processing steps that include etching or cleaning of silicon wafers with aggressive chemicals require tanks that hold and control the chemical process. Quartz tanks are impervious to the acids and bases used in wet process stations, and the high-temperature tanks can include heating and re-circulating.

The two main factors that influence the etch rate are chemical concentration and temperature.

Silicon wafer processing consists of etching the wafers to produce microscopic structures and cleaning the wafers in preparation for further process steps. Hydrochloric acid, sulfuric acid, and hydrogen peroxide are the common chemicals used for etching and cleaning the wafers, and these are corrosive chemicals. Tanks made of quartz are impervious to such aggressive chemicals, and semiconductor-grade quartz that are used in the Modutek quartz tanks is exceptionally pure, reducing the possibility of contamination. Aside from high resistance to corrosion by aggressive chemicals, quartz tanks are stable at high temperatures.

Quartz tanks are highly resistant to aggressive chemicals because quartz is a crystalline material made up of silicon and oxygen atoms held tightly in the crystal lattice.

The use of high-purity flame-polished quartz in silicon wafer processing tanks ensures that there are few non-quartz substances in the crystal lattice and on the polished surface of the tanks. This leads to the significantly reduced possibility of contamination by the tanks. Contamination of the silicon wafers can affect the semiconductor products made from the wafers. When a tiny particle or other contaminant interferes with the etching of these structures, the final semiconductor productive will come out defective or of inferior quality.

Precise temperature control is crucial because it gives improved process results. Depending on the chemical used, a higher temperature may increase the etch rate and reduce processing times. While a high etch rate is desirable, the amount of etching that occurs has to be tightly monitored because the amount of etching determines the size and shape of the microscopic structures in the silicon.

Modutek's process controls ensure that the right chemical concentration and quartz tank temperature are maintained at the correct levels, which results in precise etching control and excellent repeatability from one batch to the next. With Modutek's high-temperature quartz tanks, contamination during etching and cleaning of silicon wafers is significantly reduced. The temperature controls of the tanks provide precise settings during the process and for the subsequent batches.

Read the complete article, “How High Temperature Quartz Tanks Improve Silicon Wafer Processing,” for more details. Contact Modutek at 866-803-1533 or by email modutek@modutek.com if you have questions or would like to discuss your specific needs. 

Choosing an Acid Neutralization System to Safely Handle Chemical Disposal

Wet process semiconductor manufacturing lines use aggressive chemicals to clean and etch silicon wafers. Once the cleaning or etching step has been completed, disposing of the remaining chemicals safely is necessary.

Before being discarded, the remaining chemicals have to be neutralized first. For instance, low pH acids (like hydrochloric acid) have to be neutralized with high pH chemicals, so that it can reach the neutral value of seven. An acid neutralization system can be used continuously or in batches, and either process can be fully automated.

An acid neutralization system can be used with little supervision and will record chemical use and discharge to demonstrate compliance with environmental regulations.

The choice of acid neutralization reflects on the type of semiconductor manufacturing that takes place. For example, a continuous flow of waste chemicals is usually the result of large-scale continuous manufacturing. Therefore, a continuous acid neutralization system is ideal for this situation, as it can be designed to neutralize the outflow automatically and reliably.

The neutralization of waste chemicals in batch manufacturing is usually more complicated because each batch is different. Batch manufacturing usually takes place in developing prototypes, unique components, or small quantities of special parts. Therefore, batch neutralization is used, where the pH of the waste chemicals is measured and added with specific neutralizers (instead of adjusting chemical dosages of an established process like as in the continuous flow systems).

Once the choice of continuous flow or batch system is made, the acid neutralization system must fulfill a few basic requirements. The system capacity must be sufficient for the proposed application, with capacities ranging from a few gallons to a hundred gallons per minute. If automated, the exact automatic functions have to be programmed and set up. Finally, the monitoring and record-keeping functions have to be determined.

Another thing to be considered is the operational characteristics. If the system is automated, it may operate without supervision, but alarms will be required for situations such as low chemical supply or a pH level going beyond allowable limits. Recording of neutralization process parameters can be done digitally, with a log or on a chart recorder. Spill detection has to be incorporated into the alarm system as well, and the whole operation has to comply with environmental regulations.

For more details, read the complete article, “Choosing an Acid Neutralization System to Safely Handle Chemical Disposal”. The article discusses Modutek’s acid neutralization systems and how they can be customized to meet specific needs.  Contact Modutek at 866-803-1533 or email Modutek@Modutek.com if you have questions or would like to set up a free consultation.

5 Important Things to Know Before Buying a Wet Bench Station

Wet benches used in semiconductor manufacturing have many variations and include unique features based on the application requirements. There are several main things to consider before deciding what equipment is best suited for a specific manufacturing task. These include the type of station, how it operates, how it receives its chemicals, and what specialized or custom features are required. Five main things influence which type of wet bench to buy. 

1)     Different types of wet bench process stations have different advantages – White polypropylene construction is used for acid and base process applications such as KOH and RCA clean. Solvent application wet benches for processes using acetone, IPA, and photo resist stripping have a stainless-steel construction. Stations come with a dry-to-dry process and can include a chemical fume hood.

2)     The degree of automation depends on the application – Manual stations are ideal for initial development work when the main process parameters are yet to be determined. Once the overall process has been set, semi-automatic stations can program the fixed parameters to run automatically. At the same time, some variables can be controlled manually for optimization processes. Once the process is fully developed, fully automated stations can be used to run the production line and increase throughput.

3)     Chemical delivery systems improve process control – Chemical delivery systems run and monitor chemical storage, delivery to the process, and disposal of chemical discharges.

4)     Rinsing and drying are critical for avoiding particle contamination – Particles on wafers cause product defects. Rinsing and drying are crucial step processes as they help reduce particles on wafers, which leads to improved process yields. Special configurations such as the combined rinsing and drying station and the quick dump rinser improve process efficiency and reduce the particle count.

5)     Special custom functionality can be built into standard stations – Semiconductor equipment manufacturers that produce their own wet bench process stations in-house can add custom functionality depending on the application. For instance, the application may require etching of aluminum layers on a wafer, and a special vacuum metal etcher may have to be incorporated in the wet bench process.

Read the complete article “5 Important Things to Know Before Buying a Wet Bench Station” to learn more about Modutek’s wet benches. If you have questions, or would like to schedule a free consultation to discuss your process requirements, contact Modutek at 866-803-1533.

Improving Wafer Manufacturing Processes with Automated Equipment

Automated wafer fabrication equipment can improve semiconductor manufacturing facility performance, but all the associated process settings must be programmed properly. The settings, timing, and other parameters have to be fine-tuned before starting the manufacturing processes on a fully automated wet bench station.

As the circuit geometries and micro-structures become smaller and more tightly packed, the chemical concentrations, temperature levels and timed intervals become more critical.

Once fabrication processes (like KOH etching) are chosen in a manual operation, the process variables can be selected. Etching can be isotropic or anisotropic, and the etching precision or speed can vary. Initially, running a new process on a manual wet bench station makes sense. It allows the operator to determine the process results by rough settings of basic variables, such as concentrations, temperature, and timing, which then can be adjusted to achieve acceptable results.

A semi-automatic operation can help save time in optimizing the process steps after determining the rough settings for basic variables in manual operation. The now-fixed variables can be programmed into the semi-automatic software control, while others can be manually adjusted to get the best process results. After the variables are programmed, the process can run on the fully automated wafer processing equipment.

Fully automated wet process stations for which the process has been optimized in manual and semi-automated operations can improve overall production facility performance in several ways. Programmed settings ensure that the process can be repeated for the next batches. The use of software can help achieve accurate process parameters. It also allows precise dosages of chemicals needed in the process, while correct timing results in fewer inferior or defective products. Not to mention that full automation reduces human error and throughput and wafer yields are significantly increased.

The complete article, “Improving Wafer Manufacturing Processes with Automated Equipment” explains the process of the fully automated wafer fabrication equipment. With 40 years of experience, including in house expertise, Modutek can supply all of your automated equipment needs. Contact Modutek for a free consultation at 866-803-1533.

How Specialized Wet Bench Equipment Improves the RCA Clean Process

The RCA clean process removes contaminants from silicon wafer surfaces with so that additional wet process semiconductor manufacturing steps can occur. Specialized equipment incorporated in wet benches ensures that contaminant and particle removal is complete and silicon surfaces are clean for the next process steps.

The RCA process consists of two steps:

1) RCA Clean SC1 Step Removes Most Wafer Surface Contamination

This cleaning step uses chemicals to dissolve impurities while leaving the underlying silicon surface unaffected. The wafers are placed in a solution containing equal parts of ammonium hydroxide and hydrogen peroxide in five parts of de-ionized (DI) water. The solution is brought to 75 degrees Centigrade, and the wafers are placed in the solution for 10 to 15 minutes. Organic impurities are dissolved, and particles are removed, but a thin layer of silicon oxide forms on the wafer, and there is some contamination with metallic ions and particles.

2) RCA Clean SC2 Removes Impurities

This cleaning step removes metallic impurities. The newly cleaned wafers are placed in a bath containing equal parts of hydrochloric acid and hydrogen peroxide in five parts of DI water. The exact ration may vary depending on the application. The bath is heated to around 75 degrees Centigrade with the wafers soaking for about 10 minutes. Alkali residues, metal hydroxides, and other metallic particles are now removed, leaving the wafers completely clean and free from all kinds of particles.

Wafer cleaning equipment has to meet specialized functions. Specialized equipment is required to carry the RCA process steps effectively. The chemicals required have to be in the right quantities, and then when they're no longer needed, they need to be neutralized and disposed of safely. The concentration of chemicals is also critical, as well as the bath temperature and the timing to achieve the desired cleaning results. Contaminants and particles have to be rinsed off and filtered out. Key characteristics of effective cleaning include a low particle count on the wafer's surface and a resulting low rejection rate for fabricated wafers.

With 40 years of experience as a semiconductor equipment manufacturer Modutek has the experience, to provide the equipment you need for the RCA clean process as well as other semiconductor manufacturing applications.

For more details read the complete article “How Specialized Wet Bench Equipment Improves the RCA Clean Process”. If you would like to discuss your specific needs contact Modutek by calling 866-803-1533 or email Modutek@Modutek.com.

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

The microscopic structures produced by silicon wet etching can be created with a high degree of precision using both isotropic and anisotropic processes.

Hydrofluoric acid is one of the etchants used in isotropic etching. It etches at the same speed in all directions, independently of silicon atom density. For etchants used for anisotropic etching, such as potassium hydrochloride (KOH), the etching speed depends on the number of silicon atoms in a crystal lattice plane. It, therefore, depends on the direction of the different planes.

While isotropic etching is faster, it may etch under masks to create rounded shapes and is also harder to control. On the other hand, anisotropic KOH etching can be controlled more precisely and produce straight sides with precise dimensions.

In silicon wet etching, the etch speed also depends on the temperature. For precise control of etching processes Modutek's Teflon tanks provide rapid heating and tight temperature control. The tanks are either static or recirculating, and they can be built into any new wet bench configuration. The tanks have 360-degree overflow filtration and even heating throughout the bath. The heat-up rate is two to three degrees centigrade per minute. The temperature control accuracy is plus/minus 0.5 degrees centigrade, making these tanks ideal for both isotropic and anisotropic etching.

As for controlling etchant concentration, Modutek can provide for the injection of de-ionized water into the tanks. Because the etch speed depends on the etchant concentration, accurate concentration is essential for the final product quality and repeatability.

For more details read the recent article, “How are Isotropic and Anisotropic Processes Used to Improve Silicon Wet Etching?” . If you would like to set up a consultation, or would like to receive a free estimate, contact Modutek at 866-803-1533 or email Modutek@modutek.com.

 

 

 

How Megasonic Cleaning Reduces Cost and Improves Silicon Wafer Yields

Semiconductor manufacturing relies on wafer cleaning to remove material from previous process steps and microscopic contaminating particles. As the size of structures and circuits on wafers decreases, the tiniest particles can interfere with etching and the creation of circuits and micro-structures. Such interference can cause defects in the final semiconductor product, lower product performance, or cause reduced product lifespan.

Therefore, megasonic cleaning is the ideal cleaning process because it removes particles thoroughly but gently, leaving the wafer and its circuits and structure undamaged.

Megasonic cleaning systems generate microscopic cavitation bubbles in the cleaning solution. When the bubble bursts, it produces a tiny but powerful jet that dislodges particles from the parts' surfaces to be cleaned. Lower frequencies generate comparative larger bubbles and more powerful jets, while high frequencies produce smaller bubbles and less powerful jets.

Megasonic cleaning produces a quick and thorough cleaning of silicon wafers and does not require cleaning chemicals. As a result, it reduces the need to purchase, store, handle, and dispose of hazardous chemicals, therefore reducing costs. As megasonic cleaning reduces the need for cleaning chemicals, it results in a safer working environment for the operators who do not need to wear protective clothing when handling chemicals, which can otherwise reduce their productivity.

The effective use of megasonic cleaning that Modutek provides is through the partnership the company has with Kaijo Corporation. Kaijo is world leader in megasonic and ultrasonic cleaning technology, which provides megasonic cleaning to semiconductor manufacturing. Modutek has integrated Megasonic Cleaners into the company's wet bench equipment to produce exceptional low particle counts.

For further details read the blog article titled “How Megasonic Cleaning Reduces Cost and Improves Silicon Wafer Yields”. If you questions, or would like to set up a consultation, please call 866-803-1533 or email Modutek@modutek.com.

How Process Controls Improve Silicon Nitride Wet Etching Result

The silicon nitride wet etching process uses a phosphoric acid solution in water to quickly and effective etch mask material. However, this process is usually hard to control. The etch rate depends on the concentration of the solution and the bath temperature. Ideally, the solution has to be about 85% phosphoric acid and 15% de-ionized water at an optimized temperature of 165 degrees Centigrade. Adding water to the solution to control the concentration will change the temperature, and can be dangerous. Managing such an unstable solution with two interdependent variables is difficult, but using standard controls cannot accurately maintain the etching rate and remove the silicon nitride.

 

To maintain proper control, small amounts of water are added to the solution continuously, and the solution is maintained at its boiling point. To optimize the process Modutek introduced the silicon nitride wet etching process control solution that improves etch control and results. It features precise control of the temperature, concentration of the solution, and etch rate while ensuring the operation is safely maintained.

 

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

 

An additional thermocouple is located above the hot acid senses the presence of hot steam. Another thermocouple detects the temperature of the acid. If there's no steam or the acid becomes too hot, the process shuts down. The emergency shutdowns don't take effect during regular operation, but they are additional safety features in case of equipment malfunction or operator error.

 

For additional details on how Modutek’s control strategy improves etching rates, read the complete article, “How Process Controls Improve Silicon Nitride Wet Etching Result.” If you have any questions, or would like to set up a free consultation, contact Modutek 866-803-1533 or email Modutek@modutek.com.

 

How Wet Bench Stations Are Designed for Ergonomics and Safety

The etching and cleaning silicon wafers involves the use of aggressive and toxic chemicals that needs to be handled carefully. Ergonomic design of wet bench stations ensures safe and comfortable working conditions so employees don’t perform risky or strenuous maneuvers in the normal operation of a facility. The Semiconductor Equipment and Materials International (SEMI) S8-0712 provides safety guidelines for ergonomics engineering of Semiconductor Manufacturing Equipment to help manufacturers design equipment for safe and comfortable operation.

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

Modutek designs its wet bench chemical stations according to the SEMI S8 guidelines and minimizes the use of flammable materials in its designs and construction. Here are the examples of Modutek's safety and ergonomic design measures:

• The easy-to-hold wafer holding trays.
• All Wet Bench Stations are built around your ergonomic requirements.
• The operator interface is on a swing arm.

Modutek’s wet bench stations are built on a customer's specifications and incorporate ergonomic safety and repeatability features. Apart from ease of use, Modutek also designs each station around the customer's facility requirements.

Besides ease of use, Modutek also applies ergonomic design principles and safety features across its full product line of wet process equipment. All of the company's wet bench stations satisfy safety regulations and are designed to keep an employee's physical effort to a minimum. 

For more details, read the complete article, “How Wet Bench Stations Are Designed for Ergonomics and Safety.” If you would like a free consultation, or have questions, contact Modutek at 866-803-1533 or email Modutek@modutek.com.