Optimization of Gas Composition Used in Plasma Chemical Vaporization Machining for Figuring of Reaction-Sintered Silicon Carbide with Low Surface Roughness

Abstract

In recent years, reaction-sintered silicon carbide (RS-SiC) has been of interest in many engineering fields because of its excellent properties, such as its light weight, high rigidity, high heat conductance and low coefficient of thermal expansion. However, RS-SiC is difficult to machine owing to its high hardness and chemical inertness and because it contains multiple components. To overcome the problem of the poor machinability of RS-SiC in conventional machining, the application of atmospheric-pressure plasma chemical vaporization machining (AP-PCVM) to RS-SiC was proposed. As a highly efficient and damage-free figuring technique, AP-PCVM has been widely applied for the figuring of single-component materials, such as Si, SiC, quartz crystal wafers, and so forth. However, it has not been applied to RS-SiC since it is composed of multiple components. In this study, we investigated the AP-PCVM etching characteristics for RS-SiC by optimizing the gas composition. It was found that the different etching rates of the different components led to a large surface roughness. A smooth surface was obtained by applying the optimum gas composition, for which the etching rate of the Si component was equal to that of the SiC component.

Investigation of oxidation mechanism of SiC single crystal for plasma electrochemical oxidation

“…The oxide layer structure is well-ordered due to the chemical effect. Since the bond dissociation energy of Si–Si (310 kJ mol −1 ) is lower than that of Si–C (447 kJ mol −1 ), 29 during the oxidation process, O atoms preferentially interact with Si atoms and accept electrons from Si, 30 Si–Si bond is preferentially dissociated. As the reaction continues, a thick SiO 2 oxidation modified layer is formed on the top of SiC.…”

The Satisloh plasma polisher: plasma surface figuring ultra precision optics

“…Rapid fabrication of these ultraprecision optics requires an innovative manufacturing chain: fixed abrasive grinding, computer-controlled polishing and plasma figuring [6]. Plasma figuring is a non-contact material removal process that operates at atmospheric pressure and is based on low-cost consumables [7][8][9][10][11]. Plasma figuring of silicon based optical surfaces has been previously demonstrated using Inductively Coupled Plasma (ICP) technology on ULE® and fused silica using reactive plasma jets [12,13].…”

Systematic Characterization of Plasma-Etched Trenches on 4H-SiC Wafers

“…The etching requires the breaking of Si–C bonds, followed by the chemical interaction of reactive species with silicon and carbon to produce volatile compounds. Plasma chemistries based on highly reactive fluorine radicals generate volatile SiF x and CF x products . Accordingly, CF 4 , SF 6 , NF 3 , CBrF 3 , and CHF 3 are the typical reactant gases, even though some gas mixtures were also used. , In addition, the relative anisotropy of plasma etching, obtained by biasing the substrate, allows precise control of the line width at the subnanometer scale.…”