AVS 61st International Symposium & Exhibition
    Plasma Science and Technology Friday Sessions
       Session PS1-FrM

Paper PS1-FrM4
Mechanisms for Plasma Density Distribution Control using a Large Diameter Radial Line Slot Antenna Microwave Plasma Source

Friday, November 14, 2014, 9:20 am, Room 305

Session: Plasma Sources
Presenter: Toshihiko Iwao, Tokyo Electron Limited, Japan
Authors: T. Iwao, Tokyo Electron Limited, Japan
T. Hirano, Tokyo Electron Limited, Japan
A. Suzuki, Tokyo Electron Limited, Japan
P. Ventzek, Tokyo Electron America
K. Ishibashi, Tokyo Electron Limited, Japan
Correspondent: Click to Email
Microwave plasmas are frequently employed for etch, thin film deposition and surface activation for semiconductor or flat panel manufacturing. A major advantage of microwave driven plasma sources operating in the overdense regime or surface wave regime is that the plasmas in the high density source and lower density substrate contacting region may be well separated. This separation is useful for damage free or highly selective plasma process applications. The radial line slot antenna is an efficient microwave applicator for these process applications. Microwaves are radiated from a metal plate with a slot pattern adjacent to the dielectric top window. The electromagnetic field distribution and plasma density are controlled by optimizing the pattern. [1] Uniform plasma processes with the radial line slot antenna source have been demonstrated; however, it is challenging to overcome the tendency of the substrate-contacting plasma to become center-dense in large volume reactors under the action of ambipolar diffusion at low pressure. In this presentation, we present the results of an investigation of the effect of antenna size on the plasma density distribution for a wide gap reactor. A concurrent experimental and simulation study reveal the importance of controlling the transport parameters in the downstream wafer-contacting region to overcome ambipolar diffusion. [2] In particular, we show how the source region plasma generation impacts the electron energy distribution function in the downstream region. Anisotropic features in the electron energy distribution function plays a critical roll in controlling the plasma uniformity which we demonstrate through plasma absorption probe measurements and simulations of plasma structure.

[1] Y.Yasaka, et al., Phys.Plasmas 9, 1029(2002)

[2] J.Yoshikawa, et al., J. Vac. Sci. Technol. A 31, 031306(2013)