Combination of Plasma Electrolytic Processing and Mechanical Polishing for Single-Crystal 4H-SiC

Abstract

Single-crystal 4H-SiC is a typical third-generation semiconductor power-device material because of its excellent electronic and thermal properties. A novel polishing technique that combines plasma electrolytic processing and mechanical polishing (PEP-MP) was proposed in order to polish single-crystal 4H-SiC surfaces effectively. In the PEP-MP process, the single-crystal 4H-SiC surface is modified into a soft oxide layer, which is mainly made of SiO2 and a small amount of silicon oxycarbide by plasma electrolytic processing. Then, the modified oxide layer is easily removed by soft abrasives such as CeO2, whose hardness is much lower than that of single-crystal 4H-SiC. Finally a scratch-free and damage-free surface can be obtained. The hardness of the single-crystal 4H-SiC surface is greatly decreased from 2891.03 to 72.61 HV after plasma electrolytic processing. By scanning electron microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS) observation, the plasma electrolytic processing behaviors of single-crystal 4H-SiC are investigated. The scanning white light interferometer (SWLI) images of 4H-SiC surface processed by PEP-MP for 30 s shows that an ultra-smooth surface is obtained and the surface roughness decreased from Sz 607 nm, Ra 64.5 nm to Sz 60.1 nm, Ra 8.1 nm and the material removal rate (MRR) of PEP-MP is about 21.8 μm/h.

A Review on Precision Polishing Technology of Single-Crystal SiC

“…Electrolyte plasma was successfully applied to the precision polishing of single-crystal SiC in our previous research. Experimental results showed that the MRR can be greatly improved with low surface roughness by a combination of plasma electrolytic processing and mechanical polishing for single-crystal 4H-SiC [89,90]. Ultrasonic-assisted polishing could improve the polishing efficiency and quality.…”

Modern scientific and practical approaches to the production of substrates from semiconductor compounds А3В5. Review

“…Также есть исследования методик ХМП GaAs с использованием абразивного ледяного диска [81], с абразивом TiO 2 при ультрафиолетовом (УФ) облучении [82]. На примере 4Н-SiC исследуется методика планаризации поверхности, где кремний переводят в окисленное состояние путем плазменно-электролитического оксидирования с последующим удалением оксида абразивным составом [83]. Такой метод окисления предполагает перенос обрабатываемой пластины из электролитической ячейки на полировальник, что обуславливает трудность масштабирования технологии.…”

Recent Advances in Chemical Mechanical Polishing Technologies of Silicon Carbide

“…The analysis results of the oxide surface composition and Si 2p spectra indicated that the formation of SiO x C y and SiO 2 took place during the oxidation process. 50 Similarly, in 2021, Ma et al 51 combined Plasma-Electrolytic Processing and Mechanical Polishing (PEP-MP). It can be observed that the hardness of the single-crystal 4H-SiC surface underwent a significant reduction from 2,891.03 to 72.61 HV after PEP.…”