High aspect ratio grooving of Si using a wet etching assisted by wire-friction (A feasibility study for the applicaiotn for slicing Si ingots)

Abstract

Silicon (Si) wafers for electronic or photovoltaic devices are fabricated by slicing a Si ingot using mechanical slicing with a diamond wire. Recently, the slicing method without generating damage on Si surface has been strongly required because of the increasing demand of ultra-thin Si wafers. In this study, we have developed a novel machining method for Si grooving based on a wet chemical etching. In this method, Si was processed by the chemical etching in HNO3 and HF mixture combined with an abrasion effect of metallic wires that contains no abrasives. The extremely low kerf loss with approx. 100 μm was achieved by optimizing the composition of etchant. SEM observation showed that Si surfaces processed by the proposed method had no crack and tool mark contrary to the mechanical slicing. Furthermore, Raman microscopy exhibited that the proposed method generated no disordered layer on Si surfaces, whereas the mechanical slicing caused amorphous layers. Surface roughness was improved by adding CH3COOH to the etchant.

Keywords

• silicon
• etching
• slicing
• mixed acid
• kerf loss