Investigation on residual scratch depth and material removal rate of scratching machining single crystal silicon with Berkovich indenter

Abstract

Single crystal silicon is the basic material for the fabrication of micro-devices and micro-structures. It exhibits plastic behavior in micro/nano-machining. The key to obtain high-quality machined surfaces in ultra-precision machining of brittle materials is the material removal in ductile region. This paper focuses on single crystal silicon scratching machining in ductile region. The contact area and contact force of Berkovich indenter along two typical scratching machining directions (Φ=0° and Φ=60°) are analyzed. The residual scratch depth of typical scratching direction of Berkovich indenter is calculated theoretically. The experiments of scratching machining on (001) crystal plane of single crystal silicon using nanoindenter and Berkovich indenter are conducted. Based on experiments of nanoindenter scratching machining, the effects of normal load and scratching direction on the residual scratch depth and material removal rate in ductile region machining are investigated. Between the theoretical calculation results and the experimental results, the maximum deviation of residual scratch depth and material removal rate of Berkovich indenter scratching machining single crystal silicon is less than 3.5%. The residual scratch depth and material removal rate of Berkovich indenter scratching machining single crystal silicon along directions Φ=0° and Φ=60° are quite different. When the normal load is 10 mN and 20 mN, the material removal rate of single crystal silicon scratching machining along direction Φ=60° is more than 2 times that of along direction Φ=0°. The residual scratch depth of scratching machining single crystal silicon with Berkovich indenter varies nonlinearly with normal load, and the material removal rate is obviously affected by the direction of the scratching machining. The results in this paper are useful for the determination of process parameters for ultra-precision machining of single crystal silicon.