AVS 46th International Symposium
    Plasma Science and Technology Division Thursday Sessions
       Session PS2-ThA

Paper PS2-ThA4
Modulation Frequency Effects on Metal Etching Processes Using Pulsed-Power Plasma of Cl@sub 2@/BCl@sub 3@ Admixture

Thursday, October 28, 1999, 3:00 pm, Room 609

Session: Pulsed Plasmas
Presenter: C.J. Choi, Hyundai Electronics Industries Co., Ltd., Korea
Authors: C.J. Choi, Hyundai Electronics Industries Co., Ltd., Korea
O.S. Kwon, Hyundai Electronics Industries Co., Ltd., Korea
Y.S. Seol, Hyundai Electronics Industries Co., Ltd., Korea
I.H. Choi, Hyundai Electronics Industries Co., Ltd., Korea
Correspondent: Click to Email
Using a langmuir probe and mass spectrometry, characteristics of pulsed-power plasmas of Cl@sub 2@/BCl@sub 3@ admixtures have been investigated for Al and TiN etching. From the measurements of ion energy distributions, kinetics of positive and negative ions were studied as a function of modulation frequency. Time-modulation was carried out in the range of modulation frequency from 1 kHz to 500 kHz for a 13.56 MHz radio frequency source. As the modulation frequency decreases, densities of the positive ions such as Cl@sub 2@@super +@ and BCl@sub 2@@super +@ and neutrals were not changed significantly. However, the negative ions of Cl@super -@ and Cl@sub 2@@super -@ increase greatly due to enhancement of electron attachment reactions since high-energy electrons larger than 5 eV were cooled effectively at low modulation frequencies, especially lower than 50 kHz. Etching characteristics for the metal films were also investigated as a function of modulation frequency. Etch rates of both Al and TiN films increased with decrease of the modulation frequency in the range of 1 kHz to 100 kHz. In particular, the Al etch rate at the lowest modulation frequency, 1 kHz, dominates over that in the continuous wave plasma at a fixed average power mode. By correlating the etching characteristics with the results from the plasma diagnostics, we determined the role of negative ions, generated predominantly during the plasma-off period, in metal etching with the pulsed-power plasma. Finally, the plasma charge-up on ferroelectric capacitor was examined after the metal etching with the pulsed-power plasma.