Facing environmental challenges and enabling sustainable manufacturing

A clear focus on environmentally sustainable manufacturing is a pillar of the Linde Group philosophy, and it is Linde’s goal to enable improvements in sustainability in every industry it serves. In the solar industry, specifically in area of chamber cleaning for the very large area PECVD tools, gases like NF3 and SF6 , which are consumed in significant volumes, have some of highest Global Warming Potentials (GWPs) measured.

On-site fluorine generation (NF3 replacement)

Linde has pioneered the use of molecular fluorine (F2) as a replacement for NF3 and SF6 in PECVD chamber cleaning. While NF3 and SF6 are high GWP gases, F2 has zero global warming impact. Replacing NF3 with Fluorine in a 1GW thin film Si fab would result in elimination of NF3 consumption with an untreated global warming potential equivalent to nearly 17 million tonnes of CO2 per year.

Linde’s proven technology for generating F2 on-site and on-demand eliminates the need for large volume storage and addresses all the safety requirements for handling this reactive material. In addition to its environmental benefit, F2 reduces the time for chamber cleaning, thereby increasing plant productivity, through a more efficient etching process

SF6 Recovery

Linde has developed a packaged technology solution for capturing the high proportion of un-reacted SF6 from the cleaning process and recycling it back into the process after purification. This closed-loop technology recaptures 100 percent of the residual gas for cost-effective reuse, resulting in zero greenhouse gas emission.

Sustainable Chemical Recycling

In certain locations, for applications in mono-Si cell processing, AUECC (a Linde Group joint venture company), offers complete recycling of waste KOH via a unique reprocessing technology to yield product purity equal to original ‘fresh’ KOH quality.
Cost saving aspects of this innovative technology include reduced waste neutralization chemicals costs, reduced municipal waste effluent sewerage costs, reduced fresh purchases of potassium hydroxide , reduced freight expenses for fresh KOH deliveries and reduced operator handling expenses. Overall estimated savings are between 20-30% compared with the continued purchase of fresh KOH.
AUECC locations in Asia can also provide recycling of waste nitric acid used for multi-Si cell process and hydrochloric acid used for trace metallic contamination removal in typical c-Si processing.

For more detailed information on Linde’s enviromental approach, contact the Linde team.