AVS 50th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS1-WeA

Paper PS1-WeA9
Study of SiO@sub 2@ Plasma Etching with Off-normal Mass-analyzed CF@sub x@@super +@ Ion Beam Irradiation

Wednesday, November 5, 2003, 4:40 pm, Room 314

Session: Mechanisms in Plasma-Surface Interactions
Presenter: K. Yanai, Association of Super-Advanced Electronics Technologies, Japan
Authors: K. Yanai, Association of Super-Advanced Electronics Technologies, Japan
K. Karahashi, Association of Super-Advanced Electronics Technologies, Japan
K. Ishikawa, Association of Super-Advanced Electronics Technologies, Japan
M. Nakamura, Association of Super-Advanced Electronics Technologies, Japan
Correspondent: Click to Email
To clarify the elementary surface reactions in the fluorocarbon plasma etching, the mass-analyzed CF@sub x@@super +@ (x = 1-3) ion beam was irradiated on the SiO@sub 2@ surface at various incident angles. The noble gas ions, such as Ne@super +@, Ar@super +@, Kr@super +@, and Xe@super +@, were also irradiated to compare chemically active CF@sub x@@super +@ ions. The angular dependence of the etch yield depends on the kind of CF@sub x@@super +@ ion. In the case of CF@sub 3@@super +@ ion irradiated at 1 keV, the etch yield increases little with the incident angle below 60°, and decrease rapidly due to the reflection of the ion at the surface over 60°. The ratio of the etch yield at 60° to that of 0° is about 1.2. On the other hand, in the case of CF@sub 1@@super +@ ion at 1 keV, the etch yield increases rapidly with the incident angle below 60°. The ratio of the etch yield at 60° to that of 0° is about 2.3. In the case of the noble gas ions, the angular dependence of the etch yield does not depend on the species, indicating cos@super -2@@theta@ below 60°. The etch yields of CF@sub x@@super +@ ions were analyzed on the basis of an etching model, involving two components originated from different removal mechanisms. The chemical component, due to the thermally desorbed molecules generated through the chemical reactions between incident species and substrate materials, is constant with the incident angles. The physical component, due to the atoms sputtered away from the substrate by the momentum transfer through collision cascade, depends on the incident angle like cos@super -2@@theta@. This model can explain the angular dependence of the etch yields of CF@sub x@@super +@ ions at 1 keV very well. The chemical component of each CF@sub x@@super +@ ion is proportional to the number of the fluorine atoms in the ion with the coefficient of 1/2, consistent with the observation that SiF@sub 2@ is the main desorbed product. This work was funded by NEDO.