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Chemicals
Reduce the consumption of the six most relevant chemicals by at least 5% per year (tonnes per M$), through process optimization and recycling (baseline 1998)
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Semiconductor manufacturing processes need significant amounts of chemicals. We make strenuous efforts to minimize their use, for example, 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. This improves the management of chemicals, increases safety and reduces cost.
CHEMICALS SAVING PRIORITIES
In 1999 we formalized a Corporate Chemical Saving Roadmap based on best practise. In 2000 all our sites established a local chemical saving roadmap which adapted corporate guidelines to local conditions. Particular emphasis is given to the following programs:
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Hardware modifications to enable the use of diluted chemicals in spray processors. This system operates with much lower chemical flow rates and leads to chemical savings of about 90%, achieved with limited investment and producing a payback in less than a year. The program is being adopted by our sites where appropriate, which could save about 150 tonnes of chemicals a year
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Total substitution of sulfuric acid with deionized water and ozone in a wafer manufacturing process. Agrate in Italy was the first to use the new recipe and produced savings of 46,000 liters of H2SO4, 10,000 liters of H2O2 and 3,000 liters of ammonia during 2000. The return on investment is estimated at under four years, with cost savings of $0.07 per wafer in one pass.
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Our cumulated consumption of the most important chemicals selected for reduction (photoresists, developers, sulfuric acid, hydrofluoric acid, hydrogen peroxide, solvents) has decreased from 2.7 tonnes/M$ of added value in 1999 to 2.3 tonnes in 2000. That means less chemicals are needed to produce a wafer and consequently to generate a one dollar of added value, improving the global eco-efficiency of our chemical use.
CHEMICALS CONSUMPTION
Examples
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New equipment at our site in Tours, France, has reduced sulfuric acid consumption by 67% in a year. In 2000, 400 tonnes of sulfuric acid and 133 tonnes of hydrogen peroxide were saved. Return on investment is under two years.
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Our site in Phoenix, USA, has evaluated an aqueous substitute for a hazardous solvent used for etching. Its use will also help reduce the use of isopropyl alcohol. This solution is being implemented and the technique will be shared with other sites.
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Development work continues at our site in Agrate, Italy, on a cleaning sequence that does not need sulfuric acid and reduces the use of hydrogen peroxide and hydrochloric acid by 75%. Our researchers are hoping the process can be further developed to eradicate the use of hydrogen peroxide and ammonia.
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A new dryer in Catania, Italy, reduced isopropyl alcohol use by 108 kilograms per day (saving $392 a day). New pumps and an improvement to a manufacturing process produced chemical savings of 4,000 kilograms a year, and saved $1million a year.
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Modifications at our Singapore site saved 1,500 liters of hydrofluoric acid a year (payback of under one year). Consumption of hydrogen peroxide in 2000 was reduced by 13% per wafer.
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Our Muar plant in Malaysia has eradicated the use of sulfuric acid in some lines by simplifying the existing process, saving 81,200 liters annually, worth $15,000 per year. Improvements to the deionised water system produced savings of $21,000 a year. |
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