Change of surface impurity elements in the process of acid etching on fused silica

In order to explore the elements of trace impurities in fused silica and the change of them during HF acid etching process, the static etching experiments of 24 h, 48 h, 72 h, 96 h were performed by the mass fraction of 1% HF acid solution. The results of TOF-SIMS and XPS show that, the fused silica surface mainly contains eight trace impurity elements, including B, F, K, Ca, Na, Al, Zn, Ca, and Cr; most of these elements are in the Beiby layer, and K and Ca impurity elements are detected in the subsurface defect layer; fluosilicate salts of K, Na are generated. By analysis, during the process of HF acid etching, a part of the impurity elements will be removed, and a portion of the impurity elements and the fluosilicate salts will diffuse gradually from the surface of the fused silica to the depth with the etching liquid while some will be absorbed by fused silica surface and deposit, and the contents of them reduce gradually with the increase of the depth.