Dry etching is required to microfabricate 4H-SiC-based microelectromechanical system (MEMS) devices, such as pressure sensors and microwave power semiconductor devices. The processing efficiency can be boosted by improving the etching rate. However, adjusting the etching rate of 4H-SiC by manipulating etching process parameters not only changes the etched surface roughness, but also impacts the surface roughness of the etched surface. To achieve excellent pattern morphology and improve the etching mask lift-off quality while simultaneously improving the etching rate and reducing the surface roughness need of 4H-SiC, we optimized the photolithography process parameters, including exposure mode, exposure time, and development time, to meet the development need of 4H-SiC MEMS devices. We investigated the effects of etching process parameters (such as etching gas content, chamber pressure, and radio-frequency power) on etching rate and surface roughness in reactive ion etching (RIE) with SF₆ and O₂ as etching gas and Ni as an etching mask. The results show that a flat atomic surface can be achieved by optimizing etching process parameters. The etching rate of 4H-SiC is 292.3 nm/min and root-mean-square (RMS) roughness is 0.56 nm when the flow of SF₆ and O₂ is 330 and 30 mL/min, respectively, the chamber pressure is 4 Pa, and RF power is 300 W. High-quality etched surfaces with a high etching rate can be obtained using optimized etching process parameters.