Surface defects incorporated diamond machining of silicon

Abstract

This paper reports the performance enhancement benefits in diamond turning of the silicon wafer by incorporation of the surface defect machining (SDM) method. The hybrid micromachining methods usually require additional hardware to leverage the added advantage of hybrid technologies such as laser heating, cryogenic cooling, electric pulse or ultrasonic elliptical vibration. The SDM method tested in this paper does not require any such additional baggage and is easy to implement in a sequential micro-machining mode. This paper made use of Raman spectroscopy data, average surface roughness data and imaging data of the cutting chips of silicon for drawing a comparison between conventional single-point diamond turning (SPDT) and SDM while incorporating surface defects in the (i) circumferential and (ii) radial directions. Complementary 3D finite element analysis (FEA) was performed to analyse the cutting forces and the evolution of residual stress on the machined wafer. It was found that the surface defects generated in the circumferential direction with an interspacing of 1 mm revealed the lowest average surface roughness (Ra) of 3.2 nm as opposed to 8 nm Ra obtained through conventional SPDT using the same cutting parameters. The observation of the Raman spectroscopy performed on the cutting chips showed remnants of phase transformation during the micromachining process in all cases. FEA was used to extract quantifiable information about the residual stress as well as the sub-surface integrity and it was discovered that the grooves made in the circumferential direction gave the best machining performance. The information being reported here is expected to provide an avalanche of opportunities in the SPDT area for low-cost machining solution for a range of other nominal hard, brittle materials such as SiC, ZnSe and GaAs as well as hard steels.

Effect of Grain Size on Nanometric Cutting of Polycrystalline Silicon via Molecular Dynamics Simulation

“…In nanometric cutting of Si, the high-pressure phase transition (HPPT) to amorphous and metastable phases is thought to be a critical mechanism of ductile deformation. It significantly affects the generation of subsurface damage during machining as well as the brittle-to-ductile transition [ 43 , 44 ]. Figure 10 shows the crystal structure of the subsurface workpiece as the cutting distance reaches 70 nm, where the Si atoms are colored by CNA.…”

Industry 4.0 and Digitalisation in Healthcare

“…FEA enables modelling of stresses within a material under different thermodynamic conditions [ 124 ]. In an FEA model, the part is simulated and analyzed using representative physical behavior [ 122 , 125 , 126 , 127 ]. Such an approach demonstrates weak areas of the part, and it allows enhancement of the design.…”

Nanometric cutting: Mechanisms, practices and future perspectives

“…In this method, predefined surface defects, such as a series of holes or grooves, are introduced on the workpiece surface prior to the machining process [229]. These defects reduce the workpiece strength and ease the material removal, which was validated via SPDT of Si wafer [230].…”