Development of a process for thin metal plates with electromagnetic pressure and surface tension

Abstract

In this study, a new method of producing silicon crystal substrates is proposed as an alternative to conventional methods. The proposed method is characterised by the continuous production of plates from molten materials by surface tension and a reduction in the plate thickness by the compression effect of electromagnetic pressure. Low-melting point alloys were used in the experiments instead of silicon. In previous studies, the inefficient application of electromagnetic pressure to the molten metal and a reduction in the width of the produced substrate have been issues. Therefore, this study improved the coil shape used to apply electromagnetic pressure and to reduce the Laplace pressure acting on the liquid surface at the side edges of the molten metal, which is considered the cause of the plate width reduction. By reducing the number of coil turns, electromagnetic pressure was effectively applied to the molten metal part, the magnetic field frequency was increased and heat generation was reduced. The increased frequency was expected to enable the effective application of larger electromagnetic pressure. In addition, there was an increase in the local thickness at the side edges of substrates by installing grooves in the exit stage of the crucible, which reduced the Laplace pressure and facilitated the production of substrates with the prescribed width. Substrate production experiments were conducted with a reshaped coil and a crucible with grooves in the exit stage section, and substrates with thicknesses of less than 100 μm in several locations were successfully produced.

Keywords

• silicon crystal substrate
• surface tension
• electromagnetic pressure
• ac magnetic field
• frequency
• laplace pressure
• heat generation