Effects of plasma chamber pressure on the etching of micro structures in SiO2 with the charging effects

Many problems in ion-enhanced etching are caused by the charge-up effect as the aspect ratio increases with the decrease of a semiconductor device size. The energy and angle distribution of particles are important factors in the etching process which can be controlled by the pressure of a plasma chamber. In the present paper, we varied the pressure of plasma and studied the charge-up phenomenon for the aspect ratios 5 and 10. In the low pressure RF-capacitively coupled plasma (CCP) chamber, ions with higher energy and small angle distribution have been detected. On the other hand, in the high-pressure RF-CCP chamber, ions with low-energy and high-angle distribution are observed. At a high-aspect ratio, the charge-up potential is reduced when the pressure of a plasma chamber is high. At a high pressure, more vertical etching feature is expected.