Abstract
Silicon carbide (SiC), especially 4H-SiC, is an ideal semiconductor in power electronics due to its outstanding electrical and thermal properties. It has high hardness and brittleness, which makes it difficult to machine. To understand the nanomachining characteristics of off-axis 4H-SiC and provide suggestions on 4H-SiC substrate thinning, the nanocutting process of 4 ∘ off-axis 4H-SiC was simulated by molecular dynamics. The results showed that the stacking fault induced by cutting propagates in the basal plane, and propagates deep into the SiC workpiece when the angle between the cutting direction and the c-axis is smaller than 90 ∘ . Bond reconstruction is found near the slip plane. The cutting depth is also a key parameter in nanocutting. With smaller cutting depth, machining is more like scratching than cutting. With larger cutting depth, more atoms are involved in the cutting, cutting force and workpiece temperature are higher, and more defects exist.
Highlights
Silicon carbide (SiC) is a semiconductor with high hardness and a wide bandgap
The nanomachining characteristics of off-axis 4H-SiC have been investigated by molecular dynamics
A defect was induced by cutting propagates in the basal plane, and it was identified as a stacking fault
Summary
Silicon carbide (SiC) is a semiconductor with high hardness and a wide bandgap. It has many crystalline forms that are classified into different polytypes. The major polytypes used in electronics are 3C-SiC, 4H-SiC, and 6H-SiC [1]. The 4H-SiC is the most common for electronic devices because of its overall superior material properties [2]. To obtain single crystal SiC, the Lely method was proposed in 1954, and several modified versions were put forward. Bulk SiC crystals grown by this method often bring micropipes along the [0001] direction and other defects. The step-controlled epitaxy method was proposed by the Matsunami’s research group to overcome this problem [3]
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