| AVS 62nd International Symposium & Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS-MoA |
| Session: | Plasma Diagnostics, Sensors and Control I |
| Presenter: | Vladimir Nagorny, Mattson Technology |
| Authors: | V. Nagorny, Mattson Technology V. Godyak, RF Plasma Consulting |
| Correspondent: | Click to Email |
It is always desirable to have more than one antenna in ICP plasma source for etch for better both radial uniformity control and process window. So, configurations with two antennas are being used in ICP for quite a while. However, there is always a question about their interference.
Recently Mattson Technology introduced an etch tool with a dual frequency ICP plasma source [1]. The logic behind complementing a standard 13.56MHz antenna with a 2MHz antenna with ferrite core was quite simple - no interference between antennas, high efficiency 2MHz design [1–3] of the second antenna and respectively low additional cost. This source demonstrated large operating window, high plasma stability in both electro-positive and electro-negative gases, good process control. With this source design it is possible to tune process uniformity (Max-Min) down to 1% and better on a blanket wafer.
Energizing plasma with different frequencies put a reasonable question, if the two essentially different frequencies create similar processing plasmas comparing to a 13.56MHz drive or not. To answer this question, a comprehensive study of the electron energy probability functions, EEPF have been measured in Ar and in real processing plasmas, including gas mixtures that generate depositing plasma. The measurements performed in a wide range of processing condition with different power ratio at 13.56 and 2 MHz have demonstrated independence of the measured EEDFs on frequency, but only on the total absorbed power, gas composition and its pressure. These results are in agreement with earlier observation in different reactors [4 ] and with analysis of ionization and electron energy balances in gas discharge plasma [ 5 ].
[1] V. Nagorny, D. Lee and A. Kadavanich, US PTO Publication US20140197136, patent pending
[2] V.A. Godyak, US Patent 8920600.
[3] V.A. Godyak, C. Crapuchette, V. Nagorny, US PTO Publication patent pending.
[4] N. Hershkowitz, J. Ding, R.A. Breun, R.T.S. Chen, J. Mayer, and A.K. Quick 1996 Phys.Plasmas 3 2197
[5] V.A. Godyak 2006 IEEE Trans. Plasma Sci. 34 755