AVS 45th International Symposium
    Plasma Science and Technology Division Thursday Sessions
       Session PS-ThA

Paper PS-ThA5
Characterization of 100 MHz Inductively Coupled Plasma (ICP) by Comparison with 13.56 MHz ICP

Thursday, November 5, 1998, 3:20 pm, Room 318/319/320

Session: Diagnostics II
Presenter: H. Nakagawa, Association of Super-Advanced Electronics Technologies (ASET), Japan
Authors: H. Nakagawa, Association of Super-Advanced Electronics Technologies (ASET), Japan
S. Morishita, Association of Super-Advanced Electronics Technologies (ASET), Japan
S. Noda, Association of Super-Advanced Electronics Technologies (ASET), Japan
M. Okigawa, Association of Super-Advanced Electronics Technologies (ASET), Japan
M. Inoue, Association of Super-Advanced Electronics Technologies (ASET), Japan
M. Sekine, Association of Super-Advanced Electronics Technologies (ASET), Japan
Correspondent: Click to Email
The effect of the excitation frequency on gas dissociation was investigated using a multi-spiral coil in inductively coupled plasma (ICP). The same apparatus except for wave generators and matching circuits was used in the 100 MHz@footnote 1@ and 13.56 MHz excitation wavelength experiments. The electron density (Ne) and electron temperature (Te) in the Ar plasma were measured using a Langmuir probe. In both cases, the value of the Ne was around 2 e+11 cm@super -3@ at the excitation power of 2 kW in 3 Pa (Ar = 400 sccm). Although the Ne in 13.56 MHz plasma is a little higher than that in the 100 MHz plasma, Te (~3) in the 13.56 MHz plasma is higher than that (~2) in the 100 MHz plasma. From the dependence of the radial distribution of the Ne on the ICP source power, it was found that the 13.56 MHz-ICP was produced in a space under the coil area, and that the 100 MHz-ICP was generated throughout the reactor. This is because of the strong capacitive coupling in the 13.56 MHz-ICP, and because the inductive coupling in the 100 MHz-ICP is stronger than that in the 13.56 MHz-ICP. In the C@sub 4@F@sub 8@ / Ar plasma, CF@sub X@ (x=1, 2, 3) radical densities in the reactor wall were measured by appearance mass spectrometry (AMS),@footnote 2@ and the F radical density was evaluated using actinometry through optical emission spectroscopy of Ar (750.4 nm) and F (703.7 nm).@footnote 3@ The degree of dissociation of C@sub 4@F@sub 8@ in the 100 MHz-ICP was higher than that in the 13.56 MHz-ICP, but the CF@sub 2@ / F density ratio in the 100 MHz-ICP was 3 ~ 5 times as large as that in the 13.56 MHz-ICP. This result indicates that the dissociation of a high order (ex. CF@sub 2@ + e --> CF + F + e) in the 13.56 MHz-ICP is larger than that in the 100 MHz-ICP. Thus, it was demonstrated that the 100 MHz-ICP has a greater ability to suppress F radical generation than the 13.56 MHz-ICP. @FootnoteText@ This work was supported by NEDO. @footnote 1@H. Nakagawa et al.: Proc. 14th Symp. on Plasma Processing,136 (Hamamatsu, 1998). @footnote 2@M. Goto et al.: Jpn. J. Appl. Phys. 33 (1994) 3602. @footnote 3@J. S. Jenq et al.: Plasma Source Sci. Technol. 3 (1994) 154.