How Megasonic Cleaning Improves the Silicon Wafer Cleaning Process

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

How the Megasonic Process Cleans

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

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

Megasonic Cleaning Benefits

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

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

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

Modutek’s Megasonic Cleaning System

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

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

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

How the Advanced Ozone Cleaning Process Improves Wafer Yields and Reduces Costs

How-the-Advanced-Ozone-Cleaning-Process-Improves-Wafer-Yields-and-Reduces-CostsModutek’s advanced ozone cleaning process offers two methods that can improve silicon wafer cleaning and reduce chemical use. The main part of the process uses ozone to convert organic residue on wafers into carbon dioxide through oxidation. The wafers coming out of this process have reduced levels of particle contamination when compared to traditional cleaning methods using chemical baths. The improved cleaning performance of the patented advanced ozone cleaning process can increase facility throughput and improve semiconductor quality while reducing chemical use.

 

How Advanced Ozone Cleaning Works

With ozone cleaning in Modutek’s DryZone gradient dryer, wafers are first rinsed with deionized water to remove inorganic impurities before being exposed to ozone in an ozone chamber. The Coldstrip ozone cleaning method operates at sub ambient temperatures while Organostrip cleans at room temperature.

The ozone’s powerful oxidizing action converts the carbon of organic residue to carbon dioxide and leaves wafers clean and particle-free. The ozone is dissolved in either plain water or in a mild solvent solution and substrates receive a stable hydrophilic surface.. No harsh chemicals are required and the exhausts and waste products of the process are harmless.

 

Advantages and Benefits

The advantages of Modutek’s advanced ozone cleaning process in comparison to traditional chemical cleaning methods derive from the more compact process equipment, the absence of harsh chemicals and better cleaning performance. Benefits include lower costs, higher quality products due to lower particle counts and an environmentally-friendly cleaning process that doesn’t require compliance with onerous regulations.

Where Piranha cleaning requires as many as six processing tanks and traditional solvent cleaning five tanks, the Organostrip ozone cleaning method requires only three tanks while the Coldstrip method requires two. As a result, equipment costs and space required will be less.

One of the main issues with chemical bath cleaning is the short lifetime of the cleaning solution. The Piranha clean mixture deteriorates immediately and cleans effectively for only a few hours. Other solvents have a solution life span measured in days, after which the solution has to be replaced. Because the ozone cleaning methods do not rely on solution components that react chemically with each other, the lifetime of an ozone solution is at minimum greater than a week.

Other advantages of the ozone cleaning method are its compatibility with metal films, the absence of water stains and the low particle count. Where a typical particle count for ozone cleaning is less than 15, cleaning with Piranha solution or solvents produces particle counts in the thousands.

The resulting benefits for a semiconductor manufacturing facility can be substantial. The process costs for Coldstrip are estimated at $21,000 per year while Organostrip runs to $104,000. These amounts compare to approximately $300,000 for Piranha strip and $200,000 for other solvent methods.

In addition to saving money on process costs, the costs of chemical storage, handling and disposal must be factored in. All of these have a component for regulatory compliance that can be very costly, depending on the jurisdiction in which the facility is operating. The ozone cleaning process has no such costs.

Finally there is a key benefit to the reduced particle counts obtained with the ozone process. Subsequent diffusion and etching will result in fewer defective components and a higher quality final product. Overall, ozone cleaning allows a semiconductor manufacturing facility to improve production line performance and substantially reduce costs.

 

Modutek Can Help

Modutek offers the equipment for applying the patented ozone cleaning process to semiconductor manufacturing and can help in determining the ideal configuration for a particular application. The company also delivers equipment for traditional chemical bath cleaning methods and is therefore ideally placed to advise how the new ozone cleaning methods can improve production. Semiconductor manufacturers can take advantage of this capability to cut costs and increase productivity in their plant.

How Piranha Etch is Used in Silicon Wafer Cleaning

How Piranha Etch is Used in Silicon Wafer CleaningThe fabrication of silicon wafers is carried out with repeated etching and cleaning steps to produce the micro-structures required for the final silicon semiconductor products. Piranha or SPM (sulfuric peroxide mix) solutions can clean organic material from wafers and oxidize most metals. The powerful chemical action that makes it a favorite for resist strip and for the cleaning of wafers with organic residue also makes it difficult to use. High quality silicon wafer cleaning equipment designed to handle the corrosive chemicals safely is required for carrying out piranha etch safely and effectively.

What is Piranha Etch and How is it Used

A piranha solution is made up of a mixture of sulfuric acid and hydrogen peroxide. The most common ratio is approximately three parts acid to one part peroxide but solutions of up to seven parts acid to one part peroxide are sometimes used. The solution is highly exothermic and is prepared by slowly adding the peroxide to the acid. The mixture heats up rapidly and is often used at temperatures of around 130 degrees C. Once operating temperature and the desired concentration are reached, the wet bench equipment has to heat the solution to maintain the temperature and keep the etch rate constant.

When a facility wants to re-use a piranha solution for an extended period of time, the solution must be spiked with extra hydrogen peroxide. Hydrogen peroxide is unstable in the solution and decomposes, reducing the etching power of the bath. Spiking with additional hydrogen peroxide lets a facility use a piranha solution for up to eight hours rather than having to replace it every two hours. Spiking saves money by conserving sulfuric acid but it requires wet bench equipment that can handle the process and the spiking.

Semiconductor fabrication facilities and research labs use piranha etching to clean residue from silicon wafers and glass. The solution removes trace organic contaminants and strip residue while oxidizing metals. The underlying surfaces are hydroxilated making them hydrophilic or attractive to water, a characteristic that can be used in subsequent silicon semiconductor manufacturing process steps.

Modutek’s Silicon Wafer Cleaning Solutions

Modutek specializes in semiconductor manufacturing equipment and wet bench technology that includes solutions for wafer cleaning. The company can supply standard equipment or can customize wet bench solutions to fit specific customer requirements. Priorities are high quality materials, excellent designs, low cost of ownership and high quality results. Piranha wafer cleaning is supported by Modutek’s QFa quartz recirculating tanks and the QA constant temperature baths. Both can be installed in a wet bench station and the process can be controlled automatically, semi-automatically or manually.

The QFa series high temperature re-circulating baths provide fast even heating over a temperature range of 30 to 180 degrees C. The heat up rate can be up to 2 degrees C. per minute and the temperature control is up to plus/minus 1 degree C. The quartz bath is made of flame-polished semiconductor-grade quartz insulated with silica fiber rated up to 1260 degrees C.

The QA series constant temperature quartz baths are made from the same materials with the same control characteristics as the QFa series but they feature a magnetic stirrer, an aspirator valve system, gravity drain and a quartz bubbler. Both baths are available in standard sizes or can be custom made to fit customer requirements.

Modutek can provide a complete range of wet bench and silicon wafer cleaning equipment that includes baths suitable for piranha cleaning applications. The equipment is designed with safe and reliable operation in mind and the cleaning equipment eliminates contaminants and impurities to the greatest extent possible. Modutek wet bench equipment allows operators to use piranha cleaning methods safely to increase facility throughput while maintaining or improving output quality. Call or email Modutek for a free quote or recommendations on using the right equipment for your wafer cleaning application.

Silicon Wafer Strip Solutions for Wet Processing Equipment Applications

Silicon Wafer Strip Solutions for Wet Processing Equipment ApplicationsModutek’s extensive experience in delivering wet processing equipment allows the company to meet the particular needs of each customer. Its equipment can support a wide variety of wet bench processes and its extensive range of products can be customized to solve specialized problems for particular applications. For silicon wafer strip solutions, the company can deliver equipment to support the following applications:

Silicon Nitride Strip

The silicon nitride strip process removes silicon nitride from silicon wafers containing integrated circuits in a hot acid bath. Key factors for a high quality result are the selectivity of the bath strip solution and the repeatability of the process variables. The selectivity of removing silicon nitride while leaving silicon oxide intact must be high and the process must always deliver the same results for the same inputs.

The Modutek Nb series silicon nitride etch bath monitors bath temperature while adding DI water to maintain the acid to water ratio. The process can be tightly controlled to give excellent consistency resulting in the desired selectivity and the required repeatability.

Resist Strip

Modutek offers an advanced ozone cleaning process for photoresist strip without the use of harsh, expensive chemicals. The ozone cleaning process can strip, etch or clean silicon wafers at a lower cost than conventional technology while using an environmentally friendly and safe process.

Oxide Strip (Buffered Oxide Etch – BOE) 

The F series filtered sub-ambient circulation bath for BOE applications can cut down on acid consumption while reducing particles and improving yields. Specifically designed for BOE applications, the Modutek F series bath delivers excellent performance with a large number of options available to meet specific process requirements.

Solvent Based Resist Strip 

Modutek’s SFa series temperature controlled stainless steel recirculating baths can handle a wide variety of solvents. The baths all meet Class 1 Div 1 Group D requirements and can handle solvents such as IPA, acetone and resist strip solutions. The vessels are 316L electropolished stainless steel designed for long vessel life and operate at a temperature of up to 100 degrees Celsius. Available in a range of sizes as well as with custom dimensions, the baths are designed to handle all solvent applications.

SPM Photo Resist Strip

For photo resist strip using the sulphuric acid / hydrogen peroxide mixture SPM process, the Modutek QFa high temperature recirculation quartz baths are an ideal solution. They feature fast, even heating in a seamless, sloped flange design. Operating temperature range is 30 to 180 degrees Celsius with an approximate heat up rate of 2 degrees per minute. Process temperature control can provide an accuracy of up to plus/minus 1 degree Celsius. The quartz bath vessel is made of boron-free internally flame polished virgin fused quartz and Modutek can supply a wide range of standard and custom sizes.

Wet Processing Strip Solutions

Processing engineers considering various silicon wafer strip solutions can be confident that Modutek can supply the appropriate wet processing equipment for their application. The company has been in operation for over 35 years and provides an extensive product line of semiconductor manufacturing equipment. Their experience and expertise allows them to offer both standard equipment for common applications as well as customized solutions for applications outside the norm.

With Modutek, engineers can choose the wafer strip process they want to use, from conventional SPM, solvent or silicon nitride wet processes to the new advanced ozone technology. They can decide which is the most appropriate for their particular application. Modutek can provide recommendations on the wet processing equipment needed and also offer different options when applicable. For a free consultation or quote on selecting equipment for specific wafer strip applications call Modutek at 866-803-1533 or email [email protected].

How the Ozone Cleaning Process Improves Silicon Manufacturing Yields

How the Ozone Cleaning Process Improves Silicon Manufacturing YieldsA process that uses ozone with water or with a mild acid can clean, strip and etch wafers more rapidly and at lower cost than traditional processes. Modutek’s proprietary Advanced Ozone Cleaning Process eliminates the use of expensive chemicals while improving process performance and reducing environmentally harmful waste.

Modutek provides custom designed equipment to meet the specific requirements of customers and offers an ozone cleaning process as a solution for better silicon wafer manufacturing yields. The patented technology can replace traditional methods that use expensive chemicals and high temperatures with a room-temperature process that is environmentally friendly.

How the Ozone Cleaning Process Works

Modutek’s ozone cleaning process provides cleaner silicon wafers with reduced particle counts. For example, in Modutek’s DryZone solvent gradient dryer, the patented process rinses substrates with deionized water to remove water-miscible inorganic impurities and then exposes them to ozone in an ozone chamber. All traces of organic materials are converted to carbon dioxide. The resulting substrate surfaces are free from particles, moisture and trace organic materials and are stable hydrophilic surfaces.

For silicon wafers, the surfaces are Si-O terminated. If hydrophobic, Si-H terminated surfaces are required, a ten second post-ozone process can complete a conversion. Because the dryer uses reactive chemistries, it is particle-reducing rather than just particle-neutral.

In Modutek’s Organostrip process, wafers are exposed to an ozonated organic solvent at room temperature. The company’s technology produces very high ozone solubility in the liquid. The process results in a fast resist removal and it is compatible with all metals tested, including aluminum, copper, gold, tantalum, titanium and tungsten.

In all the Modutek ozone cleaning processes, the exact chemistry is delivered to the point of use in compact equipment that requires fewer steps and a smaller number of tanks than conventional wet benches. In contrast to traditional solvent processes, the ozone process solution has a longer useful lifespan and results in a more benign discharge. Available ozone processes include resist removal, surface preparation and final clean.

Advantages Compared to the Piranha Process

A commonly used conventional acid process is the sulfuric acid and hydrogen peroxide based Piranha process. Key advantages of the ozone cleaning process over the Piranha process include:

  • More rapid processing: Batches of 100 wafers and a rate of 6 batches per hour per process tank allow silicon manufacturing facilities to achieve a higher throughput.
  • Better compatibility: The Piranha process is not compatible with most metals while the Modutek ozone cleaning process has broad compatibility.
  • Fewer particles: The number of particles left on wafers processed with the Modutek ozone cleaning systems is extremely low while Piranha leaves particles on the surfaces.
  • Better safety: The Piranha process operates with highly corrosive chemicals heated to 130 degrees C. The Modutek ozone cleaning systems work at room temperature without harsh chemicals.
  • Lower equipment cost: With fewer tanks and process steps, the Modutek ozone cleaning systems can cost substantially less than a Piranha installation
  • Lower operating costs: Piranha process chemicals are up to twice as expensive as Modutek ozone cleaning chemicals. The total cost of ownership of a Piranha installation is much more than that of an ozone station.

Modutek can evaluate the needs of a silicon manufacturing facility and offer appropriate solutions. The new ozone technology increases manufacturing yields by reducing contaminants and can reduce overall costs. If you want a free consultation or quote on using Modutek’s ozone cleaning process to improve your manufacturing yields, call 866-803-1533 or email [email protected].

Silicon Wafer Cleaning Solutions for Wet Processing Applications

Silicon Wafer Cleaning Solutions for Wet Processing ApplicationsModutek designs and delivers standard and customized silicon wafer cleaning equipment for semiconductor manufacturing facilities and research labs. Supported cleaning processes include RCA clean, Standard Clean 1 and 2, Piranha etch clean, and pre-diffusion clean. The company has specialized in silicon wafer cleaning equipment for over 30 years and emphasizes effective and efficient contaminant and particle removal to ensure high yields, improved throughput and high quality output.

RCA Clean

The RCA clean process is based on a cleaning method developed at RCA Corporation to remove organic residue from silicon wafers. The cleaning solution is made up of 5 parts water, 1 part 27% ammonium hydroxide and 1 part 30% hydrogen peroxide. It removes organic contaminants and leaves a thin layer of oxidized silicon on the surface of the wafer.

Standard Clean 1 and 2

The RCA cleaning process is often carried out in two steps called SC1 and SC2. The SC1 step uses the APM (ammonia/peroxide mixture) solution of the RCA cleaning method to remove organic matter and particles. The SC2 cleaning method uses a solution of hydrochloric acid and hydrogen peroxide or HPM (hydrochloric/peroxide mixture) to remove metallic ions. The two steps prepare the silicon wafer for further processing.

Piranha Etch Clean

The Piranha etch clean removes large amounts of organic material. It is used when there are visible organic contaminants such as photoresist or other hard to remove organic materials. It uses the Piranha solution, made up of a mixture of hydrogen peroxide and sulphuric acid, to clean silicon wafers and hydroxylate surfaces making them hydrophilic. Typical mixture ratios are 3 parts of sulphuric acid and 1 part of 30 percent hydrogen peroxide or higher sulphuric acid ratios of up to 7 to 1. The mixture is highly corrosive and has to be handled with special care.

Pre-Diffusion Clean

The pre-diffusion clean is the final step before the silicon wafer goes into the diffusion furnace. The wafer surfaces must be free from particles and from metallic and organic contaminants. Native oxides or chemical oxide films may have to be removed.

Depending on the nature of the contaminant, a variety of aggressive chemicals, including those from the above cleaning methods, may be used to achieve clean surfaces. Pre-diffusion cleaning is critical because particles or contaminants on the wafer surface may affect the diffusion process and result in defective or low-quality semiconductor output.

Modutek’s Silicon Wafer Cleaning Equipment

Modutek’s dual tank rotary wafer etching system provides a convenient silicon wafer cleaning solution in a compact design. Once the operator loads the wafers and closes the fume door, the wafers are moved to a chemical process tank. After a pre-programmed agitation cycle, the wafers are transferred to the quenching tank where they undergo a set series of rinse cycles. When the set number of cycles is reached, an alarm sounds and the operator can remove the wafers.

Cleaning stations can be manually operated, semi-automatic or fully automated. Modutek’s SolidWorks Simulation Professional and Flow Simulation software allows customers to optimize their operation, reliably reproduce cleaning procedures and precisely control cleaning.

Modutek can evaluate the cleaning requirements of semiconductor manufacturing facilities and research labs and provide custom solutions for their specific requirements. The company’s equipment combines the latest technology with the highest quality and reliability. Modutek can provide their expertise and experience and work directly with clients to improve the silicon wafer cleaning processes for their specific application. For a free quote or consultation on call 866-803-1533 or email [email protected].

Silicon Wafer Cleaning: Effectively Removing Contaminants to Improve Yields

Silicon Wafer Cleaning: Effectively Removing Contaminants to Improve YieldsSuccessful semiconductor manufacturing relies on the effective cleaning of silicon wafers at several stages of the manufacturing process. Impurities, contaminants and residues from process steps have to be completely removed to ensure that the manufactured components have the required functionality and the desired quality. Silicon wafer cleaning equipment such as those offered by Modutek helps increase yields and improves the cleaning process to deliver high quality results.

RCA Cleaning

Standard RCA cleaning, named after the RCA Corporation where it was developed, involves immersion of the silicon wafers in hot acidic and alkaline solutions. The first bath usually contains hydrogen peroxide and ammonium hydroxide while the second bath has hydrogen peroxide with hydrochloric acid. The first solution removes organic contaminants from the surface of the silicon wafers by dissolving the bonds binding the contaminant particles to the silicon and by the oxidizing action of the chemicals. The second solution dissolves and removes alkaline residues and metallic particles.

RCA cleaning is the most common cleaning method used in the semiconductor manufacturing industry. It is especially effective in removing particles responsible for defects in semiconductors. When detected, such defects reduce the semiconductor yields of the manufacturing process and, if not detected, they reduce the quality of the resulting components.

Megasonic Cleaning

Cavitation bubbles created by the use of megasonic cleaning systems complement the chemical cleaning action of RCA cleaning. As semiconductor geometries become smaller and smaller in size, microscopic particles become more important in the creation of defects. Particles that might be too small to impact the function of large components become critical defect-producing factors for the smallest semiconductor structures.

The bubbles of megasonic cleaning systems add a mechanical component to the overall cleaning action. When the cavitation bubbles burst, they release energy that helps dislodge contaminant particles from the silicon substrate. This mechanical cleaning action can speed up the overall cleaning process and make it more effective in removing even the smallest particles.

SPM Clean – Piranha Etch

When silicon wafers are heavily contaminated, for example when contaminants are clearly visible or for the removal of photo resist after wafer processing, piranha etches provide a powerful cleaning method. The cleaning solution is made up of a mixture of hydrogen peroxide and sulphuric acid. The solution is highly corrosive and yields aggressive cleaning to remove large amounts of material. Sometimes wafers can be run through a piranha etch treatment before further cleaning with the RCA method.

FEOL and BEOL Processing

Front End of Line (FEOL) processing is the part of semiconductor manufacturing in which the components, such as transistors, are created in the semiconductor wafer, while Back End of Line (BEOL) processing involves depositing the metallic interconnections. Cleaning may be required after etching, after ion implantation or after metal deposition to remove process residue.

Water-based cleaning removes some of the impurities and RCA cleaning or piranha cleaning may be used to remove masks, photo resist or chemical residue. Ultrasonic cleaning is effective in helping remove particulate contaminants and ozonated deionized water may be used as well. At the end of each cleaning process, the wafers may be dried with isopropyl alcohol (IPA) in preparation for further processing steps.

Silicon Wafer Cleaning Equipment

Modutek has specialized in silicon wafer cleaning equipment for the semiconductor manufacturing industry and can deliver a complete spectrum of semiconductor cleaning solutions. In addition to chemical cleaning stations, Modutek incorporates the use of Megasonic cleaning equipment and IPA dryers.

Modutek silicon wafer cleaning solutions are based on the company’s thirty years of experience in providing semiconductor manufacturing equipment to the semiconductor industry. Modutek’s team of engineers can advise customers on the choice of equipment and design custom cleaning solutions for a wide variety of applications. If you need reliable and effective silicon wafer cleaning equipment in your manufacturing process, contact Modutek at 866-803-1533 or email [email protected].

How the Ozone Cleaning Process Supports Green Technology

How the Ozone Cleaning Process Supports Green TechnologyAs many people become more environmentally conscious, it is important to understand the manufacturing process behind semiconductors. The majority of companies use chemical solvents during the process, which requires special handling and is not environmentally friendly. In contrast Modutek provides equipment that uses a method that is not only more cost effective but is also environmentally friendly. This method is the Ozone cleaning (stripping) process.

There are three distinct advantages to the Ozone cleaning process:

  • Is cleaner than using a chemical cleaning processes.
  • Is more cost effective.
  • Is safer.

How the Ozone Cleaning Process Works

Most semiconductor manufacturers use chemicals in their process. While these chemicals serve their purpose, it also means that the solvents introduce another element to the process that makes it both more complex and less environmentally friendly. The chemicals must be processed in a way so that they are disposed of properly according to environmental regulations.

Modutek designed the ozone cleaning (stripping) process to both reduce the contamination inherent with the process as well as the cost. Without using chemicals, there is considerably less to cleanup during the manufacturing process. The equipment is specifically designed to reduce or eliminate the need for solvents.

One of the reasons it is more efficient and cleaner than the chemical process is that it works at ambient (room temperature) or below. By eliminating the need for chemicals like solvent base strippers or sulfuric acid and hydrogen peroxide, the Ozone cleaning process or stripping process gets the same results without needing to change the temperature of the components.

Of course, every company has its own process, and some of them require the use of at least a few solvents. In these cases, Modutek’s equipment can eliminate the use of solvents required.

Why It’s Safer

The more chemicals a process requires, the more solvent there is at the end, and the more potentially hazardous that solvent is. They must be contained and properly handled based on environmental regulations, and special training is required for those who have to handle it. There is an increased risk of spills and other risks as well.

Also, the more chemicals a company uses, the more exposure employees and customers have to those chemicals because they cannot be completely removed from the final product. There are inherent risks with any chemical a person is exposed to, no matter how small. The Ozone cleaning process (stripping process) completely eliminates the use solvents.

It’s Cost Effective

One of the biggest benefits of the process is that it is considerably more cost effective than the traditional methods. Companies do not need to invest in nearly as many chemicals to complete the process, which also means that the process will not be delayed if the supplies do not arrive when they are expected. That also means less inventory cost.

At the other end of the process, there is less to cleanup once the process is complete. Special containers for handling the solvents will not be required, and there is less hazardous waste that would need to be disposed.

While the process does require its own training, it does not have nearly as many safety risks that will require mandatory annual training to ensure safety guidelines are followed. With less personal protective gear, the Ozone cleaning process is simply more cost effective in nearly every way.

Conclusion

Traditional cleaning processes require chemical solvents, which increases the risks and the costs. It takes longer to process and dispose the required solvents, and the final product is not as clean as a product that has been through the Ozone cleaning process. In addition this alternative cleaning process is more cost effective and environmentally friendly. If you’re interested in using Modutek’s Ozone cleaning (stripping) process at your manufacturing facility contact them at 866-803-1533 for a free quote or email [email protected].

How Standard Clean Particle Removal (SC1 Clean) is Supported in a Wet Bench Process

How Standard Clean Particle Removal (SC1 Clean) is Supported in a Wet Bench ProcessSC1 Clean is the first step in the RCA clean, the procedure required before the high-temperature processing of silicon wafers. Organic impurities attached to silicon, oxide and quartz surfaces by the solvating and oxidizing actions of NH4OH and H2O2 respectively are eliminated by the particle removing solution, SC1 Clean. This solution starts a slow regeneration process whereby the silicon wafer’s original surface layer of oxide is broken down and replaced with a new layer. This regeneration process is a highly significant part of particle removal.

SC1 solution is used at 75 or 80°C for approximately 10 minutes. It is composed of:

  • 5 parts deionized water
  • 1 part NH4OH
  • 1 part H2O2

The cleaning procedure begins by heating a mixture of the deionized water and NH4OH up to 75°C. Then, add H2O2 and allow the mixture to bubble violently before using. The silicon wafer will then be soaked in the solution for 15 minutes. After, rinse the silicon wafer in a container of deionized water in order to clean off the solution. You should change the water several times in order to prevent any removed residue from clinging back on to the surface of the silicon wafer. Remember, with the new oxide layer on the surface comes ionic contamination that should be cleaned off in the following steps of the RCA clean.

Modutek Megasonic Cleaning Equipment and Features

The particular demands of the semiconductor, FPD, hard disk, solar and crystal industries are met by Modutek’s precision megasonic cleaning system. In addition, partnering with Kaijo Corporation allows Modutek to supply engineers with cutting-edge high precision cleaning technology.

You can clear 0.1 µm particles while working up to 140°C with Modutek’s Indirect (MSI Series) bath design. Or, Modutek’s Direct (MSD Series) can give you identical results with the Teflon coated Megasonic transducer. Placed in the tank, the transducer plate is ideal for using SC1 Clean and is easily accessible for installation and upgrades. With the help of Modutek’s engineers, your manufacturing equipment will be designed to work according to the requirements of your application.

Modutek’s Megasonic cleaning features include:

  • Automatic frequency tracking system
  • High efficiency generator
  • Upper and lower limit controls
  • Available frequencies: 950kHz, 2MHz, 750kHz, 430kHz and 200kHz

Modutek’s Experience

Modutek has been in the business of supplying semiconductor manufacturing equipment for 30+ years. This history is sustained by associates who will work with you from design to final installation. For a free quote call 866-803-1533.

How the Silicon Nitride Etch Process Is Supported By Modutek

The silicon nitride etch process is used in the manufacture of integrated circuits to selectively remove silicon nitride with respect to silicon oxide. Engineers and process specialists in the industry who work with semiconductor equipment manufacturers owe a great deal of their expertise to the quality of the etching equipment at their disposal today.

Background

Integrated circuit fabrication processes include selectively removing silicon nitride using wet or dry etching. Selectivity between materials removed and not removed should be high. However, selectivity is not the only consideration, in a manufacturing environment a process engineer needs consistent and repeatable results from high quality and reliable equipment.

Field Oxides Provide Mask Layer

Field oxides deposit a dielectric mask layer over silicon using a patterning mask layer exposing the silicon or oxide, and growing the thick oxide called field oxide. The preferred choice of dielectric for the mask layer is silicon nitride. This process is LOCOS, Localized Oxidation of Silicon. A poly silicon layer is frequently present beneath the nitride. This is a Poly Buffered LOCOS stack. Thus, both silicon nitride and poly silicon must be removed without affecting the silicon oxide.

Aging Effects and High Particle Count

Wet etching techniques are used for stripping nitride and silicon when oxides are present. Silicon nitride is etched in phosphoric acid that is boiling. Amounts of nitric acid may be in the bath. These baths are susceptible to aging and having higher particle counts because the silicate concentration in the bath increases. Others use separate baths for nitride and poly silicon. This increases the number of baths required and can lead to pitting of the pad oxide, which engineers overcome by using a bath with phosphoric, hydrofluoric, and nitric acids. Bath life is extended by hydrofluoric and nitric acids. Nitric acid is required to oxidize silicon. The initial etching selectivity of nitride to oxide may be undesirably low, selectivities of 9:1 observed, and depends on fluorine concentration. Higher initial etch selectivities are preferred.
Before etching silicon nitride or poly silicon to silicon oxide, you should add silicon to the etch process bath. The silicon enhances initial etch selectivity. Fluorosilicates also can be used. These compounds dissolve readily in phosphoric acid without particles. The compounds increase the etch selectivities to 40:1 and 33:1 for silicon nitride and poly silicon. The additional silicon stabilizes may be in the bath from initial use until its use is terminated. Variations of this procedure are tested and reviewed by engineers and researchers.

Equipment Innovations

IC equipment suppliers provide manufacturers and researchers with leading edge products required for producing smaller geometry semiconductors, thin-film heads, and MEMS, and also need to offer service, support, and retrofitted systems. These products are usually designed to meet specific requirements of manufacturers.

Silicon Nitride Etch Baths that Provide Safety, Control and Flexibility

The Nb Series Operation Process used with Modutek’s silicon nitride etch bath guarantees process control, safety and flexibility with a two-level diagnostic system monitoring temperature while maintaining acid to water ratio through D.I. water supplementation. By using a new remote metering system, the Nb Series is easy to install and service in new or existing stations. Process engineers know that this kind of equipment needs to be manufactured and supported by a company that:

  • Has extensive experience and expertise;
  • Uses the latest technology;
  • Meets specific customer requirements;
  • Provides high quality and reliable equipment;
  • Offers excellent technical support and onsite repairs

Modutek has over 30years of experience providing high quality and reliable equipment to support the silicon nitride etch process and is a leader among semiconductor equipment manufacturers. If you need to discuss your process requirements or would like a free quote, call Modutek at 866-803-1533 or visit www.modutek.com.