Example 3-5 Reduction of the amount of chemicals handled through reuse in semiconductor photolithography
Yokkaichi Operations, Toshiba Corp.
Toshiba had been outsourcing the collection of waste chemicals used in semiconductor photolithography to collectors and had been using newly purchased liquids in all processes. In order to reduce the amount of chemicals used, we reviewed the levels of purity required for different processes and identified those processes in which recycled chemicals having lower purity than new liquids could be used. Also, by adjusting the mixing ratio of waste liquids collected from manufacturing processes, which contain
different elements, we reduced the workload required for distillation and purification, thereby facilitating delivery of recycled products that meet purity specifications. Toshiba outsources distillation and purification of waste liquids to outside contractors. These measures made it possible to reduce purchases of new liquids by 10%. We are evaluating the possibility of using recycled chemicals in a wider range of processes.