Improving machinability of single-crystal silicon by cold plasma jet

Abstract

Single-crystal silicon has been widely applied in the semiconductor industry due to its excellent properties. However, the material is highly susceptible to surface damage during processing because of its high hardness and brittleness, thus restraining manufacturing quality and practical applications. Although methods like ion implantation have been proposed to reduce hardness and improve machinability, the efficiency is relatively low, and cannot achieve real-time adjustment of material properties during machining. In this paper, we propose a high-efficient and environmentally-friendly method to adjust mechanical properties and improve machinability of the single-crystal silicon by atmospheric-pressure cold plasma. According to nanoindentation and single-point diamond scratching experiments, the cold plasma can effectively reduce microhardness and promote deformation of single-crystal silicon. We then investigate the influence mechanism by surface characterizations using transmission electron microscope, X-ray photoelectron spectrometer, and Raman spectrometer, and discover that the cold plasma forms an amorphous silicon oxides layer on the single-crystal silicon surface. Finally, we perform micro-milling experiments with real-time plasma treatment on the single-crystal silicon surfaces to study the effect of the cold plasma on material machinability. The results demonstrate that the cold plasma can significantly improve surface quality, alleviate chip adhesion and prolong tool life. The proposed real-time cold plasma treatment method may have promising application prospects in precision manufacturing of the single-crystal silicon.