Single Crystal Silicon: Surface Evolution Regularity of Chemical Etching and Effect of Nano Jet Polishing on Damage Precursor

摘要

Single crystal silicon is a chemically active semiconductor material with good processing characteristics. With thedevelopment of technology, the role of single crystal silicon components in the field of ICF is becoming more and moreimportant. Restricted by traditional processing method and MRF, damage precursors such as scratches and impuritiesstill remain on the surface after processing. That may influence the performance of the elements.In this paper, we study the effect on the surface by two chemical etching methods and the influence on the damageprecursors of nano jet polishing. We used HF solution/HNO_3 and KOH/ isopropanol to etch the surface of the element.When the etching depth comes to 0.2 μm, pits and scratches could be easily found on the surface. After the etchingprocess, the element was processed by nano jet polishing and the roughness decreased from 1.264nm to 0.986nm.Weused nano jet polishing method to process the element polished by MRF in order to research the evolution of comet-tailscratch. The In-situ tracking method was also applied in this study. After the polishing process, the W-D (width to depthratio) increased from 30.51 to 45.84. The scratch was deactivated and the PTA (photothermal absorption) decreased from1.5413nA to 1.3500nA. The Ce impurities were also removed. Its concentration decreased from 0.1162mg/L to0.0005mg/L and the PTA of the element decreased from 0.3044nA to 0.0652nA.From the research, we can easily know that the subsurface damage exposed after the etching process. That may lay thefoundation of the nondestructive processing of single crystal silicon. After nano jet polishing process, the quality of theelement became better. The roughness and concentration of Ce impurities decreased. The damage precursors weredeactivated and the PTA decreased. In a word, chemical etching could expose the surface damage of single crystal siliconand nano jet polishing can improve the laser damage resistance.