| AVS 61st International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | Weiyi Li, University of Wisconsin-Madison |
| Authors: | W. Li, University of Wisconsin-Madison S-H. Kim, University of Wisconsin-Madison J. Blatz, University of Wisconsin-Madison B.H. Moon, Kyungsung University (Korea) Y.M. Sung, Kyungsung University (Korea) S. Banna, AMAT Y. Nishi, Stanford University J.L. Shohet, University of Wisconsin-Madison |
| Correspondent: | Click to Email |
The magnetic neutral-loop discharge (NLD) plasma was proposed by Uchida in 1994. We developed an NLD plasma reactor using a stainless-steel chamber, instead of commonly used quartz chamber in previous work. In order to examine the usefulness of this NLD reactor, low-k dielectric films are exposed to the NLD plasma under various conditions.
The structure of the NLD plasma reactor is described as follows. A cylindrical chamber lies in the middle of three sets of magnetic coils. With DC currents flowing in opposite direction in the middle set against side sets of coils, a circle on which magnetic field is zero, i.e. neutral loop(NL), can be produced in the middle of the chamber. In order to generate plasma, 13.56 MHz RF is inductively coupled into the chamber with a spiral antenna, through a quartz window on one end of the chamber. The reactor can be operated at two modes, NLD mode when there are opposite direction DC currents in the magnetic coils, or ICP mode when there are no DC currents or same direction DC currents in the magnetic coils. In NLD mode, the plasma was observed to be brighter near the NL than in the center. This difference was further confirmed with a measurement of optical spectrum using an OceanOptics spectrometer, which shows the relative plasma glow brightness at the NL is as twice high as near the center of the chamber, and about 10% higher than a non-NLD ICP plasma.
By adjusting the ratio of the DC currents running in the magnetic coils, the position of the NL can be changed. Both experiment and simulation show that the glow follows the change of NL, especially at low pressure (<1 mTorr), due to much less collision.
Low-k dielectrics are widely used in modern back-end processing, in order to reduce the R-C delay in interconnection. During processing, low-k dielectrics are often subjected to plasma exposure. The consequent damage to low-k dielectric films is presented and compared with other types of plasma reactors.
This work has been supported by Semiconductor Research Corporation under Contract No. 2008-KJ-1781 and by the National Science Foundation under Grant CBET-1066231.