Exploring the evolution of asymmetric pattern of mask hole during plasma etching process by particle simulation method

• Main Author: Peng Zhang
• Format: Article
• Language: English
• Published: Elsevier 2019-03-01
• Series: Results in Physics
• Online Access: http://www.sciencedirect.com/science/article/pii/S2211379718334569

Damage on the mask surface caused by charging effect during plasma etching process continues to attract much attention currently. It has been observed that the round shape of holes in a mask can also be etched into the asymmetric shape due to factors, such as non-uniform plasma source and incline or vibration of sample platform, etc. This work further aims to explore the charging effect when the round shaped holes in a mask has been changed as asymmetric shaped ones by particle simulation method. The distribution of electric field (E-field) produced by electrons was calculated for two systems (an isolated hole in asymmetric shape and seven asymmetric holes aligned in a hexagonal array) as well as various heights from the mask surface. It was found that the field strength reaches its maximum around the edge of a hole and presents non-uniform distribution for the asymmetric shaped hole. The non-uniform E-field distribution can affect the trajectories of ions falling on the mask surface. A string algorithm was adopted to obtain the evolution rule of these two systems during the etching process. The simulated results conclude that the final etched shaped will become the round for an isolated hole system. However, it was also found that because of the alignment of holes, the evolution rule is quite different for the case for seven asymmetric holes system. This work will be very meaningful in the study of such kinds of mask pattern for improving the physical and chemical properties of mask or for optimizing the etching process. Keywords: Plasma etching, Particle simulation, Asymmetric shape hole