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Sustainability through Materials Recovery

By Paul Stockman, Linde Electronics

Increased costs of development and manufacturing are challenging the continuation of Moore’s Law. Manufacturing processes are dependent on critical materials supplied by complex, global supply chains. Additionally, regulations are increasing and there is more of a demand for and focus on green manufacturing. To stay competitive and lay the foundation for sustainable manufacturing processes, electronics manufacturers need supply chain security, flexible logistical solutions, and a lower carbon footprint.

Because manufacturing plants are often located far from the source of materials, some materials are rare and/or difficult to procure, and being good environmental stewards is imperative to companies, recovering and reusing materials is becoming an increasingly essential consideration in order to ensure consistent quality, a stable supply of materials, and lower costs.

Linde offers three main types of material recovery solutions:

  1. On-site, closed-loop recovery – Materials are recovered on site, purified, and are available for re-use in the manufacturing process.
  2. On-site, open-loop recovery – Materials are recovered on site and are available for use in other applications.
  3. Off-site recovery – High-cost materials are recovered, shipped off site, and purified at an external facility for re-use.

Helium, argon, sulfuric acid, and xenon are vital to electronics manufacturing and are among the materials that offer real value when recovered.

On-site, closed-loop recovery

Helium, fairly rare on earth and a finite resource, is the second lightest element and the coldest liquid, making it useful in electronics manufacturing for cooling, plasma processing, and leak detection.

Several core technologies can be combined in a hybridized plant to separate, purify, and optionally liquefy helium and extend helium recovery to electronics applications, where the waste streams are often more diluted and contaminated. Groups of large fabs clustered in one major site can realize the greatest cost advantages of a helium recovery system.

The benefits of an on-site helium, closed-loop recovery system are steady access to a finite resource at lower costs.

Linde helium recovery and liquefaction plant in Skikda, Algeria

Argon: There are sufficient supplies of argon, a gas that makes up 1% of the air, to meet global demand, but users are often located far from the sources of this heavily-used material, making it challenging to get materials on time and on budget. Argon has applications in the electronics industry in the deep UV lithography lasers used to pattern the smallest features in semiconductor chips and in plasma deposition and etching processes.

Two applications use so much argon that they alone make on-site recovery worthwhile. Large amounts of argon are used daily in the manufacture of silicon wafers to protect the silicon crystal from reactions with oxygen and nitrogen while it is being grown at temperatures > 1400 o C. In addition, small drops of liquid argon are used with tools to clean debris from minute, fragile chip structures.

Argon can be recovered most economically through on-site Air Separation Units (ASUs). The process recovers 80% of the original argon, takes only minutes, and is nearly identical to the process used in the original production of argon.

The benefits of an on-site, closed-loop argon recovery system are reduced transportation costs and logistics challenges and a steady supply of argon.

On-site, open-loop recovery

Sulfuric acid: Due to its strong oxidizing properties, sulfuric acid is highly corrosive to metals, making it ideal for removing extraneous particles and cleaning semiconductors. Stringent regulations surround the disposal of sulfuric acid due to its capacity to destroy other materials and cause severe burns in humans. At very large semiconductor sites, traffic congestion can occur with the constant delivery of fresh sulfuric acid and removal of the waste.

One option is to dispose of the sulfuric acid waste by neutralizing and diluting it until it reaches acceptable, regulated levels for discharge to general waste water. Another option is to cleanse the waste for re-use, which can be done at an on-site system. This allows recovery of a high percentage of the sulfuric acid from the waste material, which is purified for re-use in electronics manufacturing¾or other¾processes.

The benefits of an on-site, open-loop recovery system are reduced disposal costs and associated demands for fresh water and waste water volumes, lower environmental impact, and decreased logistics complications and traffic.

Off-site recovery

Xenon, a very rare gas in the air, is obtained as a byproduct of the liquefaction and separation of air. It is used in electronics manufacturing in small amounts in lithography lasers and in higher amounts and concentrations in etch applications. Xenon can be used alone or as the fluorinated compound xenon difluoride in plasma etching.

Because of the low availability and high cost of xenon¾only about 10 million liters are made each year due to the low starting concentration¾it is prudent to capture the after-use, residual xenon and ship it to a rare gas manufacturing center for re-purification and packaging. The submitting fab then receives a credit for the xenon recovered at their site toward future purchases of xenon.

The benefits of recovering xenon are that it facilitates the increase in supply of the rare gas and stabilizes the cost of xenon for larger users.

Materials recovery innovations and sustainability in manufacturing processes

To meet the high demands of today and to build a sustainable future, electronics manufacturers must not only be cutting-edge in their technology, but also in their manufacturing processes. One way to do this is through implementing one or more of these materials recovery systems, which are offered by Linde. By doing so, not only will electronics manufacturers lessen the strain on natural resources, but they will also reduce their own costs, secure a steady supply of materials, and mitigate complex logistics problems.

For more information, contact Francesca Brava: francesca.brava@linde.com

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