AVS 51st International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS-WeA

Paper PS-WeA4
Real-time Monitoring of Charge Accumulated during SiO@sub 2@ Etching using Pulse-Time-Modulated-Plasma

Wednesday, November 17, 2004, 3:00 pm, Room 213A

Session: Plasma Diagnostics
Presenter: Y. Suzuki, Tohoku University, Japan
Authors: Y. Suzuki, Tohoku University, Japan
T. Shimmura, Tohoku University, Japan
S. Samukawa, Tohoku University, Japan
Correspondent: Click to Email
High aspect ratio SiO@sub 2@ contact hole etching is crucial for ULSI device fabrication. However, serious problems, such as charge-build-up damage, etching stops and microloading effect, mainly caused by charge accumulated in contact holes are not clearly solved. Therefore, it is very important to measure the amount of charges and to control such charge accumulated. In this paper, we monitored the amount of charge accumulated in real-time during the continuous wave (CW) and pulse-time-modulated (TM) plasma etching for a number of contact holes by using on-wafer monitoring device. This sensor consists of Poly-Si (300nm) / SiO@sub 2@ (1.7 µmm) / Poly-Si (300nm) layered structure on Si substrate. The diameter of contact holes was 300nm, the numbers of that were 6,400,000 and aspect ratio was 5.7. The potential differences between the top and bottom Poly-Si electrodes were measured during plasma discharge. In the case of TM plasma, the potential differences drastically reduced, compared to the CW plasma. The time-resolved measurement showed the potential differences were increased during a few tens of micro-seconds of pulse-on-time and was reduced during a few tens of micro-seconds of pulse-off-time. As the charge accumulated were saturated at the time constant of milli-seconds on the substrate surface, theresult suggests that a few tens micro-seconds TM plasma can drastically reduce the charge accumulated on the surface. The proposed on-wafer monitoring sensor can realize the real-time measurement of charge accumulated during the plasma etching processes.