Silicon Semiconductor China interviews Exyte Technology Expert Maheswaran Nair on the Star of Technology Innovation Award

First of all, congratulations on Exyte Ultra Pure Water (UPW) innovative solution winning the "Star of Technology Innovation" award. Can you briefly introduce this technology, the project and the highlights of the innovations?

Thank you very much! We are delighted to receive such a prestigious award. 

Ultra Pure Water, also abbreviated as UPW, is a type of water that meets the highest standards of purity. Contaminants are present in the form of particulate matter and dissolved impurities, organic and inorganic compounds, as well as various dissolved gases which may be reactive. UPW is achieved through a strict and stringent purification process that consists of a multiple number of stages. These involves the elimination of all the contaminants present in natural water. 

Boron is a trace contaminant in natural water, and it is difficult to achieve extremely low concentrations. For the semiconductor industry, small concentrations of Boron present in a UPW system can result in a significant decline in product yield during the semiconductor manufacturing process. Boron can also act as a dopant for silicon material. During the “doping” process, Boron atoms are introduced into the Silicon wafer substrate to alter its electrical properties and that also inevitably changes the conductivity of the substrate. Therefore, an extremely low Boron concentration in UPW is necessary in order to meet the consistent electrical property of the Silicon substrates and the product yield. Most Integrated Circuit (IC) manufacturers require Boron concentrations to be lower than 20 nanograms / liter or even lower than 1 nanogram / liter for some of the latest advanced technologies. However, the conventional UPW systems available in the market can only deliver Ultra Pure Water quality at levels typically around 15 – 20 nanogram / liter.

Exyte collaborated with a client from one of the most advanced silicon wafer manufacturing facilities in Shanghai in their request to reach lower B levels in UPW. Through engineering using an evolved combination of membrane filtration and ion exchange processes, Exyte developed a first of its kind UPW system that can consistently achieve a boron concentration of equal to or less than 1 nanogram /liter.

 

Why is UPW one of the most important elements in semiconductor production? What are the major effects of UPW during the semiconductor products manufacturing process?

UPW is used extensively in the production of semiconductor devices for all wet processing operations, including wafer cleaning, etching and polishing. The more advanced technologies even utilize UPW for immersion lithography as well. UPW purity is therefore critical to the manufacturing process of semiconductors since it directly contacts the Silicon wafers.  Total Organic Carbon (TOC), particles, bacteria, metals and anions are  key impurities that affect the product yield. Please allow me to outline each one of them.

  • Organic compounds containing polar (-OH) groups form strong bonds with the oxygen of the oxide layers within semiconductor processing, resulting in oxide breakdown and voltage leaks. The presence of organics on the oxide layers can also lead to poor adhesion of photoresist causing undercutting during wet etching processes after exposing wafers with a lithographic layer. 
  • Some organic contaminants such as Urea affect the pH of chemically activated photoresists (CAR) when exposed to ultraviolet light.  Therefore, UPW organic contamination at higher levels (> 1ppb) may cause lens hazing and improper pattern formation in Immersion Lithography.  Since the humidity is tightly controlled in the cleanroom, UPW is often added to the air.  Impurities in the UPW can then get airborne, and can also react with lithography patterns causing pattern problems.  
  • Any particles present in residual liquid layers on the wafers’ surface will result in residual deposits following evaporation during wafer drying processes. These particles often cause electrical shorts to occur on semiconductor devices.
  • Bacteria can also cause the same types of defects as other particles.
  • Transition metals can impact the p-n-junctions. Silicide-forming metals can cause dielectric breakdown. Metals cause Gate Oxide breakdown and changes in the substrate’s resistivity. 
  • Lastly, Anions can influence the adsorption behavior of metallic depositions, as well as cause corrosion to occur on metal layers.

 

Can you introduce the development trends of UPW technology? What are the special needs or challenges of UPW technology use in semiconductor process?

Many experts in this industry will agree that semiconductor manufacturing has reached the level of complexity requiring even tighter collaboration to address pressing technological challenges. Contamination levels in UPW have become more stringent as product complexity increases. Scarcity of fresh water in many regions have put pressure on fab operators to reach higher than ever water reclaim rates.  The most challenging area in water reclaim remains the control of TOC species in reclaim water to an acceptable level for UPW production.

In recent years, the continued development of membrane technology has helped to achieve the best possible reclaim rate in wafer fabs. The increased risk of contamination is a key consideration for fab operators when reclaiming wastewater streams back to the UPW system. Therefore, a more recent trend has been the development of city infrastructure to reuse the reclaimed water outside the Fab for other purposes or industries.

 

What are the specific innovations of Exyte's UPW innovative technology? What breakthroughs have been made in specific technical indicators? What are the impacts on this technology field and on the industry?

With advanced manufacturing that drives technology requirements, Exyte addresses all aspects of today and tomorrow’s challenges of our clients through innovation and collaboration with industry expertise and technology providers.

We continuously work closely and collaborate with other leading technology and equipment providers to create an edge for Exyte and cost-effective valued solutions for our clients. This also requires an innovative and upgraded process design, combined with a wealth of experience and high-level project management capabilities in the design, procurement, construction, and commissioning stages to reach the final goal.

 

Can Exyte's UPW innovation technology be applied to more Fabs or other high-tech fields?

Yes, our innovations are designed and developed around the focus of ultra-pure environmental control concepts based on leading-edge cleanroom technologies. We focus on complete client support based on each client’s specific requirements throughout all the phases from planning to commissioning and continuous improvement programs during their operations. In our UPW systems, product water quality, improved water reclaim, cost efficiency and waste reduction are the key areas of focus. 

 

As the EPC contractor of high-tech facility projects, what are Exyte's special achievements, experiences and suggestions in the construction of semiconductor projects in China, especially in the process design and project management of UPW?

Exyte is a global leader in the design, engineering, and delivery of facilities for high-tech industries. With a history of more than 100 years, the company has developed a unique expertise in controlled and regulated environments. We understand the specific challenges and demands of Advanced Technology Facilities and support our clients to achieve their next technology nodes and roadmap milestones. In China, Exyte has engineered and constructed various high-tech facilities and has completed over 300 projects since 1995.

Being the only global company serving the Semiconductor and Life Sciences markets to hold both a Grade A Building Project General Contractor License as well as a Grade A Mechanical & Electrical Project General Contractor License in China, the company is enabled to design and build facilities of all scale and sophistication.

Safety has been our topmost priority and it is about creating a safety culture and active engagement of safety amongst our colleagues, suppliers, subcontractors and clients, so that the workplace is safe, and everyone goes home safely every day. This is demonstrated in the numerous safety awards that Exyte receives in China and globally. Our commitment to safety and quality are unmatched and we have always delivered the project ahead of the schedule. 

 

Anything else you want to mention in this article.  (How Exyte helps the semiconductor industry to meet their waste reduction goals)

Globally, the Semiconductor Wafer Fabrication capacity had surpassed 100 million 300mm-equivalent wafers in 2019. Typically, each 300 mm silicon wafer processed can consume up to 5,000 liters of water, 30 kilograms of pre-mixed chemicals and 5 liters of organic solvents. That totals approximately over 500 million tons of wastewater and over 3 million tons of concentrated chemical waste annually. Semiconductor manufacturers use hundreds of complexes, high-purity organic and inorganic chemicals during wafer processing, many of which can have a severe impact on the environment if incorrectly handled or discharged, even at low concentrations. 

Growing volumes of water and chemical consumption drive the need to enhance wastewater reclaim rates. Therefore, a tailored waste management strategy is crucial for achieving Fab’s sustainability goals. Exyte collaborates with each client throughout all phases, from planning and commissioning, tool installation, process implementation and ramp-up to ongoing facility management and continuous improvement programs during operation. Our team of subject matter experts are present in every region to develop efficient waste management strategies that helps each of our clients improve the final UPW quality, costs and meet their sustainability goals.

 

Read the full article (Chinese) here.

About Maheswaran Nair

Maheswaran Nair, Manager Engineering - Process Systems at Exyte China, is a chemical engineer with over 30 years of experience in water and wastewater treatment in the Advanced Technology Facilities (ATF) market segment. He has been a key member of the technical team for several projects involving advanced high purity water and wastewater systems in Singapore, Malaysia, the United Statesand China.