Introduction of LCA

The Aim of LCA

Life Cycle Assessment (LCA) is an evaluation method. for promoting the development of products with a low environmental burden when viewed from an overall perspective. It calculates the social and environmental effect of a product throughout its entire life cycle from the acquisition of raw materials, through manufacture and use, to final waste disposal. Implementing LCA for semiconductor products will enable us to evaluate and reduce their environmental impact not only within the scope of our own company, but is also expected to evaluate the burden entailed in the acquisition of raw materials, product use, and waste disposal.

*From "Life Cycle Assessment" issued by the Japan Environmental Management Association for Industry, August 1999.

LCA procedures and inventory analysis

Impact evaluation

The environmental impact within a company is conventionally understood in terms of the energy input (fuel, electric power) and the substances with an environmental impact that are discharged during the manufacturing process, and methods have not yet been fully established to obtain a quantitative grasp of the environmental burden imposed at the production stage for materials, chemicals, and gases procured from external sources, as well as that incurred during waste disposal. A method of evaluating the impact of semiconductors during product use, when they are incorporated into devices, is also required.

Semiconductor memory LCA methods

There are two methods of carrying out LCAs. The process method involves identifying the resources actually input during product manufacturing processes, adding them up for each process from beginning to end. The site method consists of understanding the resources input into the manufacturing site as a whole, calculating the overall environmental impact, and dividing it up between products. The former method has the advantage that it reflects the different processes used to make different products, but as the processes involved in semiconductor manufacture are complex it requires massive data collection and calculations. The calculations for the latter method are much simpler in comparison, but it is difficult to analyze the differences between products made by using different processes. As the same front-end processes are used for all Elpida Memory's semiconductor memory we have adopted the site method, calculating the average environmental impact per wafer. The inventory for back-end processes mainly consists of input materials and electrical power consumed during processing.

Method of analysis
The resources and energy consumption of the manufacturing process and the resulting environmental burden are shown in the "Manufacturing Process Inventory Data table" below, while data on the input materials for a single memory product are shown in the table titled 512 Mbit FBGA Product Input Materials. Conventionally, CO2 emissions have been calculated on the basis of energy consumed during the manufacturing process, but environmental burden is now calculated inclusive of acquiring raw materials and the waste disposal process through the introduction of LCA.

Basic inventory data
A basic LCA database related to raw materials procurement is required to calculate the environmental burden (CO₂, greenhouse gas emissions) by using these inventory data. JEITA, the industry association, is going ahead with preparing these basic data for common use, and plans to analyze the burden per product unit.