Conelike Defect in Deep Quartz Etching Employing Neutral Loop Discharge

Abstract

Deep plasma etching technology of quartz has been applied to the fabrication of a microcapillary with a depth of over 20 µm. In this deep etching, defects of abnormal shape were observed on the etched surface. The shape of the defect was conelike and the defects were randomly distributed. The diameters of the defects were the same and linearly increased with etching time. Simulations were carried out using micromasks and the same defects with the same shape and expansion rate of diameter were generated on the etched surface. This implied that the micromask was the origin of the conelike defects. These defects were eliminated with the newly proposed high-bias cleaning process of only 2 min duration performed in an early period before the deep etching. This result indicated that the origin of the conelike defects were particles that fell to the surface of the quartz before deep etching.