LAUSR

Abstract Micro-structures have numerous applications for improving the surface functionability in various fields, such as surface mechanics, optics, and biology. However, machining micro-structures on brittle materials is difficult owing to the serious fractures that occur on the machined surface. To solve this problem, a method using ion implantation to modify the workpiece surface layer has been developed over the last seven years, but how to fabricate the modified layer efficiently is still unsolved and becomes a critical issue which blocks the application of this method in production. A modified layer that is thick enough for the machining is always preferred. This is difficult for the single-implantation approach studied before, owing to the large consumption in cost and time. In this study, diamond cutting assisted by multi-implantation is proposed to fabricate micro-structure array on silicon, a typical hard and brittle material. The novel method in this study shows distinct flexibility in the design of process parameters, as well as obvious improvement in efficiency. The result of surface modification is evaluated from aspects of crystal lattice and nanomechanics. The influence of channel effect is also discussed. Furthermore, chips with shear bands are discovered and analyzed in the cutting of modified silicon, which is extraordinary in the machining of brittle materials. And the brittle–ductile transition depth is significantly enhanced. Therefore, not only is multi-implantation capable of preparing thick modified layer, it also realizes further modification on material properties which is fundamental for improving the machinability. Finally, a micro-pillar array formed by 270 orthogonal cylindrical grooves (17956 micro-pillar units) is achieved in ductile mode by fly-cutting. It indicates that multi-implantation is a promising method for the micro-machining of brittle materials.