Why Particle Removal is Essential in Silicon Wafer Cleaning

During silicon wafer processing, impurities and particles are deposited on wafer surfaces or are left over from previous process steps. Such particles can cause defects in the final semiconductor product. With the reduced size of today’s silicon wafer microstructures, even the tiniest particles can block etching and affect the diffusion processes. The result appears in the final semiconductor circuit as either as a defect or reduce quality and life expectancy of the product. As a result, the focus of many wafer cleaning operations is to leave the silicon wafer surface intact but free of contaminating particles.

How Particles are Removed from Silicon Wafer Surfaces

The removal of particles can be difficult because they often have a chemical or electrostatic affinity for the silicon surface. They are attracted to the silicon wafer because of electrostatic charges and specific mechanisms have to be used to dislodge and remove them. The smaller the particle, the more such attraction may play a role and the harder it is to remove every particle from the wafer.

Mechanisms to remove particles include silicon wafer cleaning with a chemical that reacts with the particles, cleaning with a solution that dissolves the particles or washing the particles from the wafer surface. In each case, a specific type of equipment is required and traditional standard processes can be used together with new technologies aimed at removing even the smallest particles.

Cleaning Processes

Many chemical processes used to clean silicon wafers have remained unchanged since they were first used 30 years ago. These methods use aggressive chemicals to remove contamination from the wafers, which are then rinsed with de-ionized water and dried. These methods remove most of the contaminants but are less effective in removing the smallest particles. Refined older methods and new technologies such as megasonic cleaning are now often used to complete the cleaning process.

Cleaning methods used at different stages of the silicon wafer fabrication process include the following:

  • The RCA clean process, often carried out in two steps called SC1 and SC2, prepares a wafer for further processing. SC1 cleans wafers with a mixture of ammonium hydroxide and hydrogen peroxide to remove organic residue. SC2 uses hydrochloric acid and hydrogen peroxide to remove metallic residues and particles.
  • The Piranha cleaning process removes large amounts of organic residue such as photoresist. It uses sulfuric acid and hydrogen peroxide in a particularly corrosive mixture that acts quickly but must be handled with care.
  • Megasonic cleaning dislodges particles and other contaminants using microscopic cavitation bubbles generated by a megasonic cleaning system. The bubbles form and collapse in time with the MHz sound waves, delivering a scrubbing action that overcomes particle attraction to the silicon wafer surface.
  • The Ozone cleaning process uses ozone to convert organic particles and contaminants to carbon dioxide. All organic traces on a wafer surface are completely removed, leaving the silicon wafer free from particles.

One of the most critical processes for silicon wafer cleaning is the pre-diffusion clean process that takes place just before the wafers are placed in the diffusion oven. Any of the above methods or a combination of cleaning methods can be used to ensure that wafers are free of particles and the diffusion will be even and consistent.

Equipment Used for Wafer Cleaning

Modutek’s wet bench technology supports all the above cleaning methods and can be provided within their manual, semi-automated or fully automatic systems. The company can offer equipment for traditional cleaning and for the new megasonic and ozone methods as well. All cleaning equipment is available in standard configurations but Modutek can also design custom products to meet the needs of any of their customers’ silicon wafer cleaning requirements. If you need highly reliable equipment to support your semiconductor manufacturing processes call Modutek for a free consultation or quote at 866-803-1533 or email [email protected].

 

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 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].

Modutek At Semicon Conference in China

Modutek At Semicon Conference in ChinaModutek, a leading provider of leading-edge wet benches and wet process equipment, will have a factory representative at the Semicon Conference in Shanghai China from March 15-17, 2016. Modutek will be with their China Rep Laserwort located in Hall N3 at booth 3401. Information about the Semicon Conference can be referenced at http://www.semiconchina.org/ and details on Modutek’s attendance at the conference can be referenced at: Modutek at Semicon Conference in China

Stop by the Modutek /Laserwort booth to get information and answer any questions you have about Automated, Semi-Automated and Manual Wet Process Stations used for acid/base, solvent and ozone cleaning or photo resist strip. Modutek also provides IPA vapor drying and Megasonic cleaning equipment to support your manufacturing applications. In addition environmentally friendly acid neutralization systems and air scrubbers are available with all their equipment.

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

  • Fully-automated Wet Bench Equipment
    • Benefits include:
      • Full automation control with touch screen
      • SolidWorks Simulation Professional software
      • SolidWorks Flow Simulation software
      • Servo motor automation
      • All robotics and software designed in house
      • Complete design, assembly and test done according to your specifications
  • Semi-automated Wet Bench Equipment:
    • Benefits include:
      • Automation control with touch screen
      • SolidWorks Simulation Professional software
      • SolidWorks Flow Simulation software
      • Servo motor automation
      • All robotics and software designed in house
      • Complete design, assembly and test done according to your specifications
  • Manual Wet Bench Equipment:
    • Benefits include:
      • High end manual equipment at competitive pricing
      • Meets or exceeds all current safety standards
      • Designed to meet any process requirements
      • Can accommodate custom designs and processes
      • Low cost of ownership
      • Equipment designed for future expansion

Our fully-automated, semi-automated and manual wet bench equipment supports the following applications:

  • KOH Etching
  • Quartz cleaning
  • Ozone Etching
  • Ozone Cleaning
  • SC1 & SC2 featuring Megasonic Cleaning
  • BOE (Buffered Oxide Etching)
  • MEMs processing
  • Plating
  • All solvent applications
  • Hot phosphoric (Nitride Etching)
  • SPM Cleaning
  • Precision Part Cleaning
  • IPA Vapor Dryer
    • Benefits include:
      • Very low IPA consumption
      • No moving parts inside drying chamber which eliminates wafer breakage
      • Most drying cycles completed within 10-15 minutes
      • No watermarks
      • Drying technology can be easily designed into your wet bench eliminating one transfer step
    • The IPA Vapor Dryer supports the following applications:
      • Ozone Cleaning
      • Wafer Drying

Modutek has over 35 years of experience developing and building wet bench stations and wet process equipment that provides highly reliable results for precision processes. They also provide world-class service, and customer support. Call 866-803-1533 or email [email protected] for a free quote or consultation to discuss your requirements.

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].

Modutek’s Chemical Fume Hoods: Ordering Made Easy

Modutek-Chemical-Fume-HoodsWhen it comes ordering chemical fume hoods for your lab, Modutek gives you a wide variety of options to meet your requirements. With our wet processing capabilities, we can add the features you require that give you flexibility and overall design advantage. Whether you require a table top exhaust hood or a freestanding hood supported with a HEPA filter filtration system, Modutek can customize our equipment to meet your specifications and requirements.

There are no catalog numbers to limit your choices. All lab and research projects have their own unique equipment requirements. We are your one-stop shop that can provide all your lab equipment needs for all types of wet processing, wet bench and related manufacturing. Below are the features and benefits of Modutek’s chemical fume hoods and how we make ordering easy:

  • Modutek’s chemical fume hoods are made from high-quality materials. This includes stainless steel construction to handle solvent applications and white polypropylene to handle acid and base processes.
  • Each unit is manufactured having electrical outlets at deck level. The units can be manufactured using standard, ground-fault circuit interrupter (GFI) or explosion proof electrical outlets. GFI outlets are required in most states since they provide the best protection from electric shock. Explosion proof electrical outlets are used in hazardous and corrosive environments. Choose the outlet that best suits your manufacturing needs.
  • If you need a chemical fume hood built with a utility sink with a gooseneck faucet, we offer that option. This type of faucet is an option many of our customers choose as part of their requirements.
  • Temperature controlled chemical baths are also available with our chemical fume hoods or exhaust stations for your laboratory.
  • Modutek’s chemical fume hoods can also be designed with overhead fan filter units (FFU) if they are part of your requirements.
  • A carboy chemical containment system is included with our chemical fume hoods. This system captures waste solvents produced during wet processing, and other related chemical processing applications.
  • Counter balanced safety shields are also provided with the chemical fume hoods manufactured by Modutek.
  • Overhead LED lighting is also included on-deck.
  • Custom designed chemical fume hoods built per your specifications. What does your specific application require? What size and length chemical fume hoods do you need? We can create any size and length to meet your requirements.

Other options you can get on your Modutek chemical fume hood include dedicated drains to carboy with DOT containment, lift stations designed into the benches, fan filter units (HEPA), Teflon N2 gun and DI water hand spray, and extended warranty. If you need additional information on Modutek’s chemical fume hoods you can contact us at 866-803-1533.

Chemical Fume Hoods – Using Technology to Keep Workers Safe

Chemical Fume Hoods are necessary for businesses that use caustic chemicals or cleaners that are hazardous for those working around them. Modutek Corporation, which has been in business since 1980, manufactures some of the best Chemical Fume Hoods available today.

Properly designed and installed Chemical Fume Hoods are necessary to reduce a lab worker’s exposure to hazardous fumes, vapors, gases and dust created during lab tests. They are also used for Research and Development (R&D) analysis and in University laboratories. A Chemical Fume Hood works by confining any hazardous airborne material as well as diluting it with large amounts of air. This is drawn through an exhaust and filter system which is then expelled through the roof of a building or, if a company chooses a ductless system, the air is filtered and re-circulated.

Chemical Fume Hoods designed and manufactured by Modutek are used in a variety of applications in a number of different industries. They can remove and filter smells, fumes, gases, airborne chemicals, dust and other related airborne contaminants. Modutek’s Chemical Fume Hoods provide quick and low-cost hazardous chemical exhausting to keep your work area safe for your employees.

Some of the benefits of using the Modutek’s Chemical Fume Hood system include:

  • Low-cost of ownership that comes with a one-year warranty on all parts; however an extended warranty is available.
  • Meets or exceeds all current industry safety standards.
  • Our Chemical Fume Hoods are easy to install and set up.
  • Chemical Fume Hoods can be designed to meet your current testing needs.
  • We work closely with each client to setup a specific custom design or configuration.
  • The equipment is designed to allow for future expansion.

There are a number of options available for Modutek’s Chemical Fume Hoods including a ductless fume hood design that collects fumes directly from the source and re-circulates the filtered air. The ductless application comes with carbon filter, dust filter or can be used with fume/air scrubbers. Ductless Chemical Fume Hoods can be used with a fume/air scrubber or other similar filters and do not evacuate air to the outside.

Other options for the Chemical Fume Hoods designed and manufactured by Modutek include, but are not limited to:

  • FM4910 (PVC-C) material of construction
  • Utility sink with gooseneck faucet
  • Easily accessible electrical outlets at deck level
  • Fan Filter Units (HEPA)
  • A lift station designed into the bench
  • Drains dedicated to carboy with DOT containment
  • Overhead deck lighting
  • Teflon N2 gun and DI water hand spray
  • Counter balance safety shields

If you would like more information about the Modutek Corporation Chemical Fume Hoods, or any of our other products, please contact us today at 866-803-1533.