Abstract: High-purity β-SiC powders are used as raw materials for semiconductor wafers, semiconductor kiln furniture and ceramic devices used in semiconductor chip equipment. A subcritical hydrothermal method was used to remove metal impurities in β-SiC powders synthesized by high-temperature and high-pressure, which promotes the hydrothermal reaction. The removal effect of common metal impurities in β-SiC powders under different acid systems was studied. The content of trace elements was detected by inductively coupled plasma optical emission spectrometry spectrometry (ICP-OES), and the phase composition and microstructure of β-SiC powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results are as follows: the HCl system is better for Cr and Zr removal than the other two; the HCl+HF+HNO₃ system is better for Ca, Fe, Mg and Ti, and H₂SO₄+(NH₄)₂SO₄ system is better for Al and K. The best reaction temperature for treatment with HCl system is 200 ℃, the best reaction temperature for treatment with HCl+HF+HNO₃ system is 220 ℃, and the best reaction temperature for treatment with H₂SO₄+(NH₄)₂SO₄ system is 200 ℃. Among them, H₂SO₄+(NH₄)₂SO₄ system reduces the content of common metal impurities in β-SiC powders to the minimum, and the total content of impurities is 920.31 mg/L. Therefore, H₂SO₄+(NH₄)₂SO₄ system is the optimal scheme for β-SiC powders impurity removal.

Key words: β-SiC powder, hydrothermal method, metal impurity, inductively coupled plasma, purification