Environmental Impact and Material and Energy Balance of the Integrated Circuit Production Cycle

This paper analyzes the material and energy flow of the wafer processing production chain, which from silicon, leads to integrated circuits. These devices are used in the manufacturing of a wide variety of commodities and in the management of productive processes. It is observed that in order to obtain a wafer the following are necessary: between 0.8-1.1 kg of quartzite, 1.3-2.2 kg of carbonic materials (coke, woodchip etc.) more than 6.5 kg chemical products (acids and solvents), 40-60 kg of gases (mainly nitrogen), 3.5-6 m3 of water and an energy consumption of approximately 250-500 kWh (equal to 2-4.5 GJ of primary energy). The resulting wafer most widely used today is 200 millimetres in diameter, 50 grams in weight, from which it is possible to obtain 170-230 chips. The planning and production of the wafer (silicon semiconductor) has centred on the possibility of placing an ever-increasing number of transistors onto a chip. Once assembled, forming various integrated circuits, this chip allows the manufacture of increasingly smaller commodities with rapidly growing capabilities in performing function. The production cycle has remained constant during the last fifty years. However, with regards to energy and material flow, some technical innovations can be observed, which have allowed the reduction of particular inputs, such as the amount of MG-Si (Metallurgical Grade Silicon), electricity, water, or chemical substances, of which some are toxic and have a strong environmental impact.