Development of plasma-based atom selective etching: a novel polishing technique for single-crystal materials

Zhang, Yi (2021) Development of plasma-based atom selective etching: a novel polishing technique for single-crystal materials. Doctoral thesis, University of East Anglia.

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Abstract

To address the problem of polishing difficult-to-machine singly-crystal materials, especially SiC, and provide a potential solution to the fabrication of truly-atomically flat surface, a novel polishing technique called plasma-based atom selective etching (PASE) is proposed in this thesis. PASE featuring ultrahigh polishing precision could outpace the state-of-the-art polishing method: chemical mechanical polishing (CMP). In this research, the material removal rate of PASE is thousands of times higher than that of CMP. The fast polishing of single-crystal material can be realized by selectively removal atoms which form the roughness and leave behind the integral perfect single-crystal basement. The underlying mechanism of PASE is based on the difference of chemical activity of atoms at different sites and aims at the maximization of the difference using proper reaction conditions. Ab initio molecular dynamics (AIMD) simulations have been performed to explore the mechanism. Several prototype machines with the optimal plasma nozzle and torch have been developed throughout the experimental tests. Also, experiments and characterizations have been conducted to optimize the parameters of PASE and verify the speculated mechanism. To demonstrate the advantages of PASE, many difficult-to-machine materials, including SiC, GaN, Si, Al2O3, and AlN, have been examined; in particular, discussions on SiC have been mainly conducted. It is noted that a sliced SiC with a roughness over 100 nm has been successfully reduced to the atomic level (Ra ~ 0.05 nm) within 5 minutes by an ultrahigh material removal rate of ~ 30 μm/min. Furthermore, broader applications of PASE, including dislocation detection and subsurface damage measurement, have been provided to demonstrate its technological advance.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Engineering
Depositing User:	Chris White
Date Deposited:	23 Mar 2022 10:57
Last Modified:	20 Jun 2023 11:05
URI:	https://ueaeprints.uea.ac.uk/id/eprint/84214
DOI:

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