Effect of 13X Zeolite Modified with CuCl2 and ZnCl2 for Removing Phosphine from Circular Hydrogen of a Polysilicon Chemical Vapor Deposition Stove

Abstract

Silicon materials used in semiconductor and photovoltaic products have strict purity requirements. The quality of materials will be affected severely if even trace amounts of PH3 are contained in the hydrogen of the chemical vapor deposition (CVD) stove. Thus, it is critical that the content of PH3 be controlled under a certain level. In contrast to series of metal oxide adsorbents reported in other research, 13X zeolite modified with ZnCl2 (Zn-13X) and CuCl2 (Cu-13X) was prepared to adsorb trace PH3 in this study. Breakthrough curves and adsorption capacities at different temperatures from −15 to 50 °C were investigated to determine the performance of the adsorbents. X-ray diffraction and surface analysis were carried out to characterize the adsorbents and the adsorption mechanism. The results showed that CuCl2 was dispersed on 13X in monolayer or submonolayer form, and ZnCl2 would change the structure of 13X under the experimental condition. New diffraction peaks at 35.6° and 38.8° appeared after loading CuCl2 in the X-ray diffraction pattern of Cu-13X, and the peak of Zn-13X at 10° almost disappeared. The half-pore width after modification was mainly centralized at 0.5 nm for each of them, and the specific surface areas of Cu-13X and Zn-13X were 245.2 and 19.2 m2/g, respectively. The breakthrough time for Cu-13X was always more than 600 min, whereas it sharply decreased from 350 to 20 min for Zn-13X when the temperature increased to 50 °C from −15 °C. The static adsorption capacity decreased from 106.5 mg to 67.2 mg and from 88.3 mg to 36.1 mg of PH3, respectively, for per-gram Cu-13X and Zn-13X as the adsorption temperature changed in the chosen range. The working life of Cu-13X could be prolonged by N2 purging at room temperature according to experimental results because the rate of chemical reaction coupled with the adsorption between PH3 and the active components was much slower than that of its physical adsorption, but a higher temperature was needed for Zn-13X.