Improving Silicon Wafer Cleaning with the Piranha Etch Process

The Piranha etch process removes organic material from silicon wafers rapidly and completely. Semiconductor manufacturing involves the repeated etching and cleaning of the silicon wafers and the Piranha mixture is a favorite method for the resist strip of wafers to prepare them for further processing. Modutek can provide high temperature re-circulating and constant temperature quartz baths and the company has developed a new “bleed and feed” control method to improve the silicon wafer cleaning process.

Modutek Quartz Baths for Piranha Etch

Modutek quartz baths are based on extensive experience and the use of the highest quality materials. The baths themselves are made of virgin boron-free fused quartz in a flame-retardant polypropylene housing. The QFa series is a high temperature re-circulating bath with a temperature range of 30 to 180 degrees centigrade while the Qa series is a constant temperature bath with the same temperature range.

Both bath series are temperature controlled to plus/minus 1 degree centigrade with a heat-up rate of 2 degrees centigrade per minute. Process control can be fully automated, semi-automatic or manual. The baths are available in a variety of sizes and Modutek will construct custom units as required. The units are ideal for Piranha etch applications because of their quick and even heating, accurate temperature control and extended vessel life.

Improving Piranha Process Control

The Piranha process uses an aggressive mixture of sulfuric acid and hydrogen peroxide to dissolve organic residue on the silicon wafers. The mixture is heated to about 130 degrees centigrade to improve the strip speed. Control of the cleaning is difficult because mixing sulfuric acid and hydrogen peroxide is exothermic and heats up the solution when the mixture is first prepared. As the mixture cools, it has to be heated to maintain its temperature and the strip rate.

The hydrogen peroxide in the mixture is unstable and decomposes to form water, diluting the mixture and slowing the strip rate. Heating the mixture increases the rate of decomposition of the hydrogen peroxide. To keep the concentration and the strip rate constant, the sulfuric acid and hydrogen peroxide mixture is periodically spiked with extra hydrogen peroxide. This addition keeps the strip rate elevated but the overall process is hard to control and the mixture has to be replaced completely about once per day. To improve the Piranha process and silicon wafer cleaning, the concentration and temperature variation issues have to be addressed.

The Modutek “Bleed and Feed” Process Control Method

Modutek has developed a method of improving control of the Piranha process by using a two tank system with a clean and a dirty tank. When the concentration of hydrogen peroxide goes down, a small amount of mixture from the dirty tank is drained and discarded. The drained amount is replaced from the clean tank. The stripping process can continue and the concentration is maintained at the desired level. The clean tank has its sulfuric acid and hydrogen peroxide replenished. All “feed and bleed” amounts are programmable to match specific process variables.

Benefits of the Process Change

The “bleed and feed” control method can be fully automated and the frequent addition of small amounts of sulfuric acid and hydrogen peroxide mixture keeps the strip rate constant and allows for continuous use of the mixture over an extended period of time. The benefits include:

  • Savings of chemicals can reach 75 percent while chemical purchase and disposal costs are correspondingly lower.
  • Process efficiency is increased due to less downtime for replacement of the chemicals.
  • Process results are improved due to a more constant strip rate.

As a leading semiconductor equipment manufacturer, Modutek provides customers with high quality equipment that offers the highest degree of process control. Modutek supports the new “bleed and feed” process change for Piranha strip in the company’s new wet bench stations. Call for a free consultation to discuss your specific process requirements.

Selecting a Wet Bench Manufacturer That Meets Your Process Requirements

Semiconductor device fabrication can be a complex process. Often, it can take as many as eight weeks to complete a manufacturing cycle. During this process it’s critical to use wet bench stations that are built with high quality components that work reliably. This is needed to ensure that every manufacturing process involved complies with important industry standards.

How do you choose the right wet bench manufacturer and station to ensure that all your process requirements are met? There are a few areas that you need to consider:

Confirm the Wet Bench Station That Directly Meets Your Needs

A wet bench needs to address all your requirements.

  • Do you need full automation, semi automation or manual control? Fully automated stations use robotics for all the process steps and are typically used to optimize through put on well developed process. Semi automated stations use robotics for some process steps with some operator interaction. Manual wet bench stations are least expensive option and are often used when developing a new process that requires a manual interaction and does not use any robotics for automation.
  • The use of compatible materials is important. You need to consider what kind of processes engineers will use the wet bench for, and confirm the kind of fire-resistant plastics that must be used.
  • Consider the types of chemicals that will be used in the wet bench. Will corrosive chemical solvents be used? If solvents such as Acetone, NMP or Photo Resist Striping will be used a stainless steel solvent station will be need that uses corrosion-resistant material and provides fire suppression features.
  • The wet bench manufacturer should supply equipment that is in compliance with all fire safety and electrical safety codes.

If it’s difficult to find a ready-designed wet bench unit that needs all these needs, you should consider contacting the manufacturer for a custom solution.

Choose a Turnkey Solution

A wet bench manufacturer should be a one-stop outlet that has an extensive product line. They should offer complete, fully integrated systems. A complete turnkey solution is what you should choose. You should order your semiconductor wet process equipment from a vendor who not only provides you with the wet bench that you need, but also includes full installation, after sales service, technical support, and warranty support. If the unit is capable of accepting improvements and updates down the line, such improvements should be offered by the vendor, as well.

Look at Reputation and Longevity

Look for a vendor who comes with a good reputation for product quality and customer service and has been in business for awhile. Wet bench equipment is a long-term purchase. It can be beneficial to maintain a relationship with the supplier, for help with installation, repairs and updates along the way. It is also important to choose a well-established supplier. A wet bench manufacturer who has been business for decades is likely to stay in business and honor the warranty support offered.

Choose Modutek for Your Wet Bench Needs

Modutek has been the leading supplier of wet bench and wet processing equipment for over 38 years. During this time, the company has become one of the leaders and innovators in the business. Modutek does more than supply standardized wet bench equipment. The company offers clients the ability to customize and configure their equipment as they need it. Modutek’s design engineers work closely with clients to meet specific requirements.

Modutek designs all its equipment and software in-house, and, for this reason, is far more capable of offering perfectly customized solutions, when compared to other manufacturers who outsource much of their design and software.

Modutek Offers a Wide Range of Options

Semiconductor fabrication is complex process. Clients are usually not able to accept one-size-fits-all solutions. It is for this reason that Modutek offers a number of options.

Fully automated wet benches: These appliances offer wafer fabrication, using the company’s own SolidWorks Simulation Professional software. The system is known to improve production times, with high throughput for better yields.

Semi-automated wet benches: Semi-automation offers greater precision than manual control, but is more affordable than full-automation. A servo-activated robot offers three levels of automation. Just as with fully automated wet benches, the semi-automated ones come with deep software control.

Manual wet benches: These appliances offer all the features of the automated and semi-automated ranges, except that they do not use robotics. Equipment of this kind can be affordable, and it is expandable, as well.

Modutek’s wet benches offer dry-to-dry processing. They allow drying without the need to use separate appliances. It speeds up wafer processing, and allows for higher yields.

Modutek is one of the best-known names in the wet processing industry. All of Modutek’s products are designed and assembled at the company’s facilities in San Jose. With its year-long guarantee on all its products, and a name that has set high standards for quality and reliability. Modutek is a premier semiconductor wet bench manufacturer and wet process equipment supplier that you can trust. Call 866-803-1533 for a free consultation to discuss your specific process requirements.

 

Modutek at 2019 Semicon Conference in China-Hall N3 Booth 3243

Modutek Corporation, a leading supplier of wet bench stations and wet process equipment, will be at the Semicon Conference located at the Shanghai International Expo Center in China from March 20-22, 2019. At the Conference Modutek and their factory representative Laserwort Ltd., will be located in Hall N3 at booth 3243. Additional details about the Semicon Conference in China can be referenced at: http://www.semiconchina.org/

Representatives at the Modutek /Laserwort booth will be available to answer questions and provide information on using Wet Bench Stations for acid/base, solvent and or photo resist strip.  In addition Modutek will also provide information about the benefits of their new IPA vapor dryer with the HF last process. Modutek serves customers around the world and builds customized wet bench stations and wet processing equipment for customers in many industries including pharmaceutical, biochemical, solar and semiconductor manufacturing.

Additional details on some of Modutek’s products are listed below:

Single Chamber HF Last IPA Vapor Dryer

Benefits include:

  • Very low consumption of IPA
  • Most drying cycles completed within 10 to 15 minutes
  • Eliminates watermarks
  • No moving parts inside drying chamber eliminating wafer breakage
  • Drying technology can be integrated into wet bench eliminating one transfer step

Features include:

  • Single drying chamber for DI water rinsing and IPA vapor drying
  • Easy to change IPA bottles
  • Filter bypass for contamination control with no cassette contact points
  • On board HF metering for precision mix ratios
  • Uses an in situ HF etch process with a rinse step before the IPA drying cycle
  • Handles all process sizes (standard wafer carriers to glass substrates)

Fully-automated Wet Bench Equipment

Benefits include:

  • In house customization to meet customer process requirements
  • Precise automated process execution and reliable repeatability
  • Full automation control with touch screen
  • Improved yield and reduced errors
  • SolidWorks Simulation software for accurate calculation of process parameters
  • All robotics and software design designed in house
  • Complete design, assembly and test at one location to meet your specifications

Semi-automated Wet Bench Equipment:

Benefits Include:

  • Automation control with touch screen
  • Servo motor automation
  • SolidWorks Flow Simulation software
  • SolidWorks Simulation Professional software
  • All robotics and software designed and developed in house
  • Complete design, assembly and test at one location to meet your specifications

Manual Wet Bench Equipment:

Benefits Include:

  • High end manual equipment at competitive pricing
  • Meets or exceeds all current safety standards
  • Low cost of ownership
  • Designed to meet any process requirements
  • Can accommodate custom designs and processes
  • Equipment designed for future expansion

All wet bench equipment supports the following applications:

  • KOH Etching
  • Quartz cleaning
  • Ozone Strip
  • Ozone Cleaning
  • SC1 & SC2 (RCA Clean)
  • Megasonic Cleaning
  • BOE (Buffered Oxide Etching)
  • MEMs processing
  • All solvent applications
  • Hot phosphoric (Nitride Etching)
  • SPM Cleaning
  • Precision Part Cleaning

Modutek has over 38 years of industry experience and expertise in designing and building wet bench stations and wet process equipment that provides highly reliable and consistent results for precision processes. They also provide world-class service, and customer support. Contact Modutek for a free consultation or quote at 866-803-1533 or email [email protected].

Why Pre-Diffusion Cleans Are Important for Silicon Wafer Cleaning

Why Pre-Diffusion Cleans Are Important for Silicon Wafer CleaningPre-diffusion cleans are carried out several times during the semiconductor manufacturing process, and each time the chemical residues and particles on the wafers have to be removed as completely as possible. If silicon wafers still have surface contamination when they are placed in the diffusion oven, diffusion may be uneven and the resulting semiconductor products may be defective.

The several methods available for wafer cleaning either use chemical baths or Megasonic cleaners to remove surface contaminants from the silicon wafers. Modutek offers a complete line of wet bench stations that support pre-diffusion wafer cleaning as well as other semiconductor fabrication processes.

The Importance of the Pre-Diffusion Wafer Cleaning Process

The contamination with particles on silicon wafer surfaces prior to diffusion is a key factor in reducing the yield of electronic components in semiconductor fabrication plants and research facilities. Particles may be diffused into the silicon and create electric defects or they may block diffusion behind the particle. After diffusion, particles may affect etching and interfere with microscopic conductors. The resulting electronic components may have to be scrapped.

As microscopic structures in silicon become smaller and more detailed, large particles become more disruptive on both an electrical and the physical scale. Even tiny particles that were previously considered unimportant can affect the smallest silicon structures. When electronic products are defective, it affects facility productivity and reduces throughput. Performance is lower and profitability is reduced. In some cases, the products are not defective but their life expectancy may be reduced and the manufacturer’s reputation is affected. An effective pre-diffusion wafer cleaning process results in fewer defects and a higher quality output.

How Pre-Diffusion Cleaning is Carried Out

Before being placed in the diffusion oven, silicon wafers are immersed in chemical or Megasonic baths. Surface impurities are dislodged, dissolved or chemically neutralized. Complete cleaning may take more than one process and the following methods are commonly used.

RCA cleaning is a popular method consisting of two components, SC1 and SC2, where the SC stands for standard clean. For SC1, the wafers are immersed in a solution of ammonium hydroxide and hydrogen peroxide. The aggressive chemicals remove all organic compounds from the wafer surfaces but may leave traces of metallic contamination. As a result, during SC2, the wafers are placed in a mixture of hydrochloric acid and hydrogen peroxide that removes any remaining metal ions.

An alternative to the RCA standard clean methods is the Piranha clean, especially useful for applications with heavy wafer contamination. It consists of a sulfuric and hydrogen peroxide mixture that rapidly removes material such as photo resist. A further feature of Piranha clean is the hydroxylation of the silicon wafer surface, making it hydrophilic or attractive to water, a characteristic useful for some subsequent process steps.

Megasonic cleaning uses high-frequency sound waves in a cleaning solution to dislodge contaminants from the surface of the silicon wafer. This cleaning method does not use harsh chemicals, and a generator is used to produce a signal in the MHz range at a specified power level. A transducer in the cleaning tank converts the signal to sound waves in water. The sound waves create microscopic cavitation bubbles with a strong scrubbing action that removes particles. Depending on the manufacturing process, semiconductor manufacturing facilities use one of these methods for pre-diffusion cleaning.

Modutek Pre-Diffusion Cleaning Equipment

Modutek’s wet bench chemical stations provide a complete range of pre-diffusion cleaning solutions. The company can offer equipment that supports each of the above cleaning methods as well as other semiconductor fabrication processes. All of Modutek’s pre-diffusion cleaning baths produce silicon wafers with extremely low particle counts while all of the company’s equipment is designed for high quality output, fast processing and efficient operation resulting in superior manufacturing facility performance. Contact Modutek for a free consultation or quote on equipment designed to meet specific manufacturing requirements.

Advantages of Using the KOH Etching Process

Advantages of Using the KOH Etching Process for Silicon EtchingThe KOH etching process uses a potassium hydroxide solution to etch silicon wafers and produce microscopic structures in the silicon. In subsequent semiconductor fabrication steps, the micro structures are used in the manufacture of integrated circuits, processors and other electronic devices.

Compared to other etching processes KOH etching is comparatively safe, etches silicon rapidly and can be tightly controlled. These characteristics are especially important for batch processing when a process step has to be reproduced precisely many times. While other chemical processes are required for specific semiconductor cleaning and etching steps, industrial plants and research facilities prefer the KOH process for general silicon etching.

How the KOH Etching Process Works

The KOH solution is prepared by adding KOH to water in an etching tank made of material impervious to aggressive chemicals. Silicon wafers are masked with silicon nitride or silicon dioxide, substances that the KOH solution does not etch. When the wafers are immersed in the KOH solution, silicon is removed from the areas that are not masked by the chemical action of the KOH etching solution.

The etch rate can be controlled by changing the concentration of the solution and by changing the temperature. The concentration is fixed once the process is established and is usually around a 30% solution by weight, but may be as low as 10% and as high as 50%. Typically the solution temperature is about 60 to 80 degrees centigrade and the etch rate increase is very sensitive to an increase in temperature.

Other factors influencing the etch rate are the crystal lattice planes of the silicon and the presence of boron doping. Different crystal lattice orientations are etched at different rates so that the crystal lattice planes influence the design of the masks and their placement. Boron doping can be used to stop the etching in a specific direction. Taken together, all the ways the etch rate can be controlled allow the creation of complex shapes in the silicon.

Controlling KOH Etching

Obtaining the desired etching results from the KOH process can be divided into two groups of control measures. The concentration, doping and lattice orientation are determined initially before the process starts and establishes itself. At that point, temperature control can still change the etching rate. The initial control measures can be put in place with the required precision, concentration and other characteristics but the temperature of the etching solution must be controlled accurately on a continuing basis.

Because the KOH etching process is very temperature sensitive, maintaining the temperature at the exact set point is important. The temperature controller must be accurate during the process and also from one batch to the next. Tight control during the etching process ensures that the etch rate remains constant while precisely keeping the same temperature for a given set point from one batch to the next ensures accurate reproducibility of process conditions and identical output across different batches.

Modutek’s Teflon Silicon Etch Tanks

Using Modutek’s Teflon tanks allows operators to fully benefit from the advantages of KOH etching. The tanks are designed with KOH etching in mind and feature a wide temperature range, tight temperature control and rapid heating. Custom sizes are available and custom installations can be designed to fit any new or existing wet bench application.

Heating in the Modutek Teflon tanks is either in line or through an immersion heater in the overflow weir. Temperatures can be controlled to plus/minus 0.5 degrees centigrade and the temperature range is 30 to 100 degrees centigrade. The heating rate is 2 to 3 degrees per minute, depending on the size of the system, and heating is even throughout the bath. Since temperature control is a key requirement for successful KOH etching, these system characteristics allow for excellent reproducibility between batches and for the precise control needed for high quality output.

Apart from excellent temperature controls, the Modutek Teflon tanks feature all TFA Teflon with advanced manufacturing techniques designed to minimize contamination. Options such as an auto lid feature or a condensing refluxor are available if needed. Modutek Teflon tanks are an ideal solution for KOH etching applications and the company can help select the model and options that best satisfy specific customer needs. Contact Modutek for a free consultation on selecting the right equipment for specific process requirements.

Why Chemical Lift Station Pumps Are Needed for Wet Bench Stations

why-chemical-lift-station-pumps-are-needed-for-wet-bench-stations2Once a wet bench process step is completed, the remaining chemicals and waste water have to be drained and transferred to an area for neutralization and disposal. Depending on the physical layout of the semiconductor manufacturing facility, gravity draining may either not be possible at all or may be insufficient in terms of flow and speed. Chemical lift station pumps take over the transfer of chemical solvent in a controlled and optimized way. The removal of chemical solvents and waste liquids is accomplished rapidly and completely, leaving the wet bench station ready for a new process step.

Lift Station Pumps for New Installations

While it may be possible to design new installations without lift station pumps and relying only on gravity drains, changes in the facility, expansions or upgrades may require the retrofitting of pumps. In that case, lift station pumps have to be included in separate stations that are often located behind the wet bench stations. These separate stations take up valuable floor space that could otherwise be dedicated to productive process elements. As a result, incorporating lift station pumps in new wet benches is more desirable.

Modutek can add lift station pumps to their wet bench stations and use them to pump acids, solvents and related chemicals and solutions in their semiconductor manufacturing equipment. The lift stations automatically monitor the lift station tanks. When fluids are detected in the tank via the installed level sensors, the corresponding pump is activated to transfer the liquid from the processing station to the facility’s neutralization area. Incorporating the lift pumps in the processing stations is an efficient and compact solution for new installations.

Adding Lift Stations to Existing Processing Lines

When wet bench processing lines are used with a new process or are upgraded, the gravity drains that were previously adequate may no longer deliver the required flow. Lift stations have to be added to deliver the anticipated performance. Often extensive customization of the lift stations is required to accommodate them in the existing facility.

Modutek can help find solutions to adding chemical lift stations to wet processing lines. The company has a complete line of chemical lift stations for installation outside existing wet processing stations. Modutek engineers evaluate process requirements and plant layout to propose equipment that works best for a particular application.

Modutek’s chemical lift stations have all-plastic fluid paths for resistance to corrosion and feature an automatic constant ON with level sensing governing operation. Standard pumps are vertical centrifugal polypro with other pump options and a double containment option available. The polypro holding tank can be built to the size required and the designs are customized to meet flow requirements. Level sensing is via four float-type level sensors signaling low/low, low, high and high/high. Remote control is available.

Modutek Delivers Customization and Support

Modutek can analyze the requirements of a wet bench installation and propose ideal solutions because the company designs and builds their wet bench equipment in house at their facility in San Jose. With almost 40 years experience in wet bench technology, Modutek has the expertise to find optimum solutions and implement them using their own equipment. Chemical lift stations for existing installations and lift station pumps incorporated into new wet bench stations often require extensive customization. Such customization can include different geometry, size, materials, and control logic to meet unique customer requirements. Modutek can rely on in house experience to adapt its equipment for a specific application. Once delivered and installed, Modutek can provide unparalleled customer support because the company doesn’t use third party suppliers. The Modutek specialists carrying out wet bench and lift station service are backed up by the Modutek personnel who designed and built the equipment.

Why Preventative Maintenance of Wet Bench Equipment is Important

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

Scheduling Preventive Maintenance

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

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

Carrying Out Preventive Maintenance

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

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

Coordinating with a Competent Supplier

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

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

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

How the IPA Vapor Dryer Improves Wafer Processing Results

how-the-ipa-vapor-dryer-improves-wafer-processing-results

Not every advancement in semiconductor fabrication produces results that are usable in industry. To be of value, advancements need to be consistently repeatable when used on an industrial scale. Modutek’s IPA vapor dryer falls into this category, helping semiconductor fabricators improve both yields and processing times.

Modutek’s IPA vapor dryers are custom-engineered with in-house experts working in partnership with a client’s technical staff. From a thorough understanding of a client’s manufacturing process, Modutek works to make sure their equipment is designed and tested to meet the requirements.

The Marangoni IPA Vapor Dryer Design

Silicon wafers require cleaning, rinsing and drying at certain stages of the fabrication process. The results need to be as close to perfection as possible, with no watermarks, and minimal particle contamination. In the past, these results were obtained through rapid spinning and heat drying. These simple methods no longer work with the latest high-density wafers, however. Not only is water hard to remove from complex shapes, drying without leaving watermarks is impossible.

Contamination from incorrect cleaning and drying can cause serious product malfunction and high failure rates. This is where drying by isopropyl alcohol comes into play. IPA drying by the vapor method, delivers wafers that are completely free of watermarks and with minimal contamination. Modutek’s IPA vapor drying system is both cost-effective, and ready for seamless integration into the standard wet bench process or free-standing design.

How the IPA Vapor Dryer Design Works

Modutek’s IPA vapor dryer design is unique in a number of ways. This design delivers high-quality results through serving IPA vapor at the upper reaches of the drying tank. This makes sure that vapor distribution is even. Since the surface tension of isopropyl alcohol is lower than that of water, such vapor serving introduces a gradient of surface tension where isopropyl alcohol meets with a layer of water on the wafer surface. With this type of drying effect, water quickly leaves the wafer surface, and leaves it completely dry and clean. Since the water does not actually evaporate, it leaves the watermarks behind. The drying process takes no longer than 15 minutes.

The Advantages of Modutek’s IPA Vapor Dryer

Modutek’s in house experts in IPA vapor dryer design work together with a clients’ technical team to design and create IPA dryers that specifically meet their application requirements. Clients are able to come to Modutek’s facility for testing to make sure that their equipment works as expected.

With extensive experience in the wafer processing industry, Modutek is fully able to provide top-notch equipment and customer support at every stage of the design process, during delivery and after the sale. With expertise in semiconductor processing equipment, Modutek is able to address every specific client need for this industry. Contact Modutek for free consultation on the equipment needed for your specific wafer manufacturing process.

 

 

 

How to Qualify Which Semiconductor Equipment Manufacturers Meet Your Requirements

how-to-qualify-which-semiconductor-equipment-manufacturers-meet-your-requirementsThere are a number of things to keep in mind when you review which supplier to use from a list of semiconductor equipment manufacturers. From the ability of a manufacturer to customize solutions to meet specific client needs, to company reputation, the quality of the equipment sold, and after-sales support, there is a lot to consider. Only after you create a shortlist of potential companies to work with should you consider pricing and other minor details.

The Customization Question

Whether the need is to upgrade lines or replace old equipment with new machines, every semiconductor foundry or research facility is different, and comes with very specific requirements. Often, equipment newly purchased needs to be able to interface with systems already in place, and at other times, space or system size concerns override all other areas of consideration.

Equipment may also need to be internally customized with specific feature additions in order to be able to deliver on client requirements. Equipment manufacturers need to provide extensive experience and expertise with such customizations. Before a specific semiconductor equipment manufacturer can be chosen, they need to be able to demonstrate that they are able to work with clients, and to supply systems that are customized to their needs.

Reliability of Equipment

Once equipment has been purchased and set up, it needs to stay online for long stretches of time with minimal downtime. The best way to determine if a manufacturer is able to supply equipment of such description, is to contact references and study reliability statistics. Suppliers should be asked to furnish detailed information on scheduled downtime requirements, and logbooks obtained from actual installations.

After-Sales Support

Equipment warranties and support capabilities are the last item on the list to look at before a contract is signed with a selected supplier. Warranty policies should be simple and straightforward, and yet be comprehensive in describing what’s covered. All new equipment should typically come with at least a one year warranty.

It’s also important to check on the strength of every company’s service department. The most generous warranty policy would not be of much use if there were few personnel able to deliver on it. If there are third-party service providers that are on call, rather than an in-house department, it might be a warning sign that the manufacturer is not well-equipped to deliver a quality after-sales experience. Since third-party service providers usually deal with products from multiple companies, they are not likely to be as expert in their fields as in-house personnel. The best way in which to check on a company’s service ability is to simply call with a question prior to purchase.

Use a Supplier with a Proven Track Record

Finding the right equipment supplier is a vital step in the set-up of a semiconductor manufacturing facility or research center. The equipment from a supplier will affect future productivity, and quality of output. Since many suppliers have come and gone over the years look for one that has a proven track record that has been around for awhile. In addition the systems and equipment they sell should be continually improved to keep up with the latest technology and allow for easy upgrades.

Modutek’s Experience, Expertise and Longevity

Modutek has over 35 years of experience as a semiconductor equipment manufacturer, and has continually operated during that time to improve their equipment and address the needs of many clients. Not only does Modutek design and assemble their own equipment, all their software is designed in-house as well. They provide expert support through its own employees, rather than though agreements with third parties. In addition Modutek is committed to complete customer satisfaction, and has a record that shows it. Contact Modutek for a free quote or consultation to discuss your specific semiconductor manufacturing equipment requirements.

 

How New Equipment Has Improved the Silicon Nitride Wet Etching Process

how-new-equipment-has-improved-the-silicon-nitride-wet-etching-processThe silicon nitride wet etching process is difficult to control safely but is a key component of semiconductor wafer manufacturing. The process uses phosphoric acid to remove silicon nitride masks from silicon wafers to allow the clean wafers to undergo further fabrication steps. The hot phosphoric acid and water mixture is unstable and requires periodic addition of small quantities of water, but adding water to phosphoric acid may produce a bump. Modutek has developed a new approach to control the nitride etching process safely and accurately while achieving high etching rates.

How the Silicon Nitride Wet Etching Process Works

The etching of silicon nitride masks with phosphoric acid is optimized at a temperature of 160 degrees centigrade for a mixture of 85 percent acid and 15 percent deionized water. At this temperature, the mixture boils and some water is lost as steam. The lost water has to periodically be replaced, but adding water to phosphoric acid can be dangerous. The water may not immediately mix with the acid, instead forming a film on top of the mixture. If the film suddenly mixes with the acid, introducing a large amount of water into the mixture at once, a bump can result.

In order to optimize etching performance small amounts of water are added periodically which immediately mix with the acid to maintain the temperature at the ideal 160 degrees centigrade. If too much water is added, the temperature of the mixture may drop and the mixture may stop boiling, allowing the water film to form and create a dangerous situation. If too little water is added, the temperature of the mixture will increase and even more water will be lost. Modutek has new equipment provides an innovative control strategy that addresses these issues and delivers excellent etching performance.

Modutek’s Nb Series Silicon Nitride Wet Etching Bath

Modutek’s new Nb series bath provides tight control of the bath temperature while ensuring a safe operation and superior etching of the silicon nitride masks. In addition to the new control strategy, the series Nb baths offer additional safety features that make sure the dangerous condition in which large amounts of water are mixed with hot phosphoric acid is avoided.

In their new silicon nitride wet etching equipment, Modutek uses the acid mixture concentration as a reference value for adding small amounts of deionized water. At normal operation, the bath heater is on and the mixture is always boiling at the normal mixture boiling point of 160 degrees centigrade.

The boiling point of the mixture varies with the concentration. As water is lost and the mixture concentration rises, the boiling point increases as well and the mixture temperature starts to rise above 160 degrees centigrade. This rise triggers the addition of a small amount of deionized water. Since the mixture is always boiling because the heater is always on, the deionized water is immediately mixed in with the boiling acid, the concentration of the acid is reduced and the mixture boiling point decreases back down to 160 degrees centigrade.

To guard against the addition of water when the mixture is not boiling, a thermocouple sensor above the boiling mixture detects the presence of steam and closes the water valve when no steam is present. This additional safety feature ensures that a dangerous water film cannot form even under abnormal conditions such as heather failure.

Modutek has been testing and fine tuning the new system with Nb silicon nitride wet etching baths to customers in manual, semi automated and fully automated wet bench stations. Semiconductor fabrication facilities and research centers using the new equipment have achieved an average etch rate of 65 angstroms per minute while limiting oxide etch as the controls ensure safe operation at a consistent and optimum operating point.