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Chemicals
| Recycle the most used chemicals: e.g. for sulfuric acid recycle > 30% by end 1997 and 80% by end 1999. |
Semiconductor manufacturing processes require significant amounts of chemicals. ST is working in all directions to save these hazardous substances: by substitution, process optimization, hardware modifications, on-site generation, recycling for reuse, and the installation of Total Chemical Management (TCM) in partnership with key suppliers, to name a few. This will improve the management of chemicals in terms of safety, tracking and cost.
NEW
Reduce the consumption of the six most relevant chemicals by at least 5% per year (tons per million dollars of added value) through process optimization and recycling. |
Engineers working on wet processes (cleaning processes using chemicals) are at the forefront of our efforts in chemical saving programs. In addition to the undeniable benefits to environmental health and safety, these initiatives bring significant savings in cost, as well as better process performance.
In 1999 ST formalized a Corporate Chemical Saving Roadmap based on the best practices of all sites. Particular emphasis is given to the following programs:
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use of diluted chemicals in spray tools through hardware modifications (low flow pick-up in spray tools). A saving of 90% has already been demonstrated and the program is being cascaded to all front-end operations; |
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total sulphuric acid substitution by de-ionized (DI) H2O and O3 for the resist removal processes. Two programs were developed in 1999 with two different suppliers. Both processes were qualified by ST's wet process engineers in Fab 3 and Fab 8 in Agrate, Italy and the program will be deployed to all ST operations. |
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650 tons of sulphuric acid and hydrogen peroxide were saved in Tours, France, through upgrading of equipment and process modifications. |
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A reduction of 99% in isopropyl alcohol (IPA) was demonstrated using a new dryer at the Company's M5 fab in Catania, Italy. This program will likewise be extended to other operations. |
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In Agrate, Italy, significant reduction in chemical use is being achieved through twin clean process. This process allows a substitution of sulphuric acid, hydrogen peroxide, hydrogen fluoride and ammonia and a reduction of hydrogen chloride. |
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In 1999, a new ultra pure chemical free system was constructed at ST's Rousset site, where the association of new water treatment techniques permits the production of high grade water quality based on continuous de-ionization processes without the need of chemical regenerations. Double pass reverse osmosis units followed by an electro-de-ionization system and non-regenerable mixed beds resins now produce up to 150 m3 per hour without any contaminated effluents to be treated. |
At a Corporate-wide level, the cumulated consumption of the most relevant chemicals selected by the Company (photoresists, developers, sulphuric acid, fluorhydric acid, hydrogen peroxide, solvents), have decreased from 4.9 tons per million dollars of production value in 1998 to 4.2 tons in 1999.
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