AVS 58th Annual International Symposium and Exhibition
    Plasma Science and Technology Division Tuesday Sessions
       Session PS2-TuA

Paper PS2-TuA1
Prediction of Ion Sheath Shape and Ion Trajectory during Plasma Etching Processing using On-Wafer Monitoring Technique

Tuesday, November 1, 2011, 2:00 pm, Room 201

Session: Plasma Diagnostics, Sensors and Control I
Presenter: Ryosuke Araki, Tohoku University, Japan
Authors: R. Araki, Tohoku University, Japan
K. Miwa, Tohoku University, Japan
T. Kubota, Tohoku University, Japan
T. Iwasaki, Mizuho Information & Research Institute, Inc., Japan
K. Ono, Mizuho Information & Research Institute, Inc., Japan
S. Samukawa, Tohoku University, Japan
Correspondent: Click to Email
Precise plasma processes are indispensable for the fabrication of ULSI and MEMS devices. Some MEMS devices have larger scaled 3D structures comparable to the ion sheath thickness on the surface in plasma processing. In such cases, because of distortion of sheath shape due to the MEMS structure, ions trajectory are distorted to the surface and it causes etched shape anomaly. In order to solve these problems, we are developing a system to measure sheath thickness and to predict sheath shape, ion trajectory, and etched shape by fusion of a new on-wafer monitoring data and computer simulation. Our newly developed on-wafer sheath shape sensor can measure the surface potential and ion saturation current at wafer surface. Based on these results, the sheath thickness, shape, and ion trajectory were calculated by using our developed simulation. In this study, we could measure the sheath thickness, and then calculate the sheath shape deformation around a structure having large step in the case of using SF6 inductively coupled plasma. We found that the sheath thickness was about 1 mm and ion trajectory was bent near the large steps on the wafer surface. This result was completely corresponding to the actual etching pattern profile near a structure having large step. It is suggested that our proposed fusion system of on-wafer monitoring data and computer simulation is very effective to predict real etched shape during plasma etching processes.