Heating efficiency and energy saving potential of Czochralski crystal growth furnaces

Environmental concerns and rising energy costs have increased attention to energy efficiency in growing semiconductor crystals from melt, traditionally a highly energy-intensive process. The energy conservation measures have so far generally been limited to the ventilation and air-conditioning of production facilities, with far less attention paid to the process equipment. In the present work, a thermodynamic limit is established as the baseline for evaluating the energy efficiency of industrial crystal growth processes. It is then shown that the typical industrial furnace has energy demands far above this strictly necessary limit. Measurements on a research-scale furnace with induction and resistance heating along with numerical simulation with validated models are used to identify the sources of energy loss in the furnace and possible ways of improving energy efficiency. Measurement results show that switching to induction heating can lead to energy savings of roughly 35%. Simulations demonstrate the utility of numerical modes in gaining a detailed understanding of the thermal performance of the furnace and identifying the improvement and optimization measures.