AVS 52nd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS+MS-ThM

Paper PS+MS-ThM4
Effects of an Insulating Focus Ring on a Uniformity of Radical/Ion Distributions in a Wafer Interface in a 2f-CCP Etcher

Thursday, November 3, 2005, 9:20 am, Room 302

Session: Process Equipment Modeling
Presenter: T. Yagisawa, Keio University, Japan
Authors: T. Yagisawa, Keio University, Japan
T. Makabe, Keio University, Japan
Correspondent: Click to Email
Technological improvement in efficiency of reactive ion etching of oxide film is still a main issue in plasma etching under the circumstances that the size of the wafer has been continuously increasing from 100 mm in diameter in 1975 to 300 mm in 2003, as well as the miniaturization of ULSI. The etch rate of SiO@sub 2@ in a fluorocarbon plasma is a function of the mixture between the accumulation of radical species on the surface and the impact energy of ions incident on the wafer. Through a series of numerical studies by using VicAddress in addition to the experimental ones, we have demonstrated that a 2f-CCP (two-frequency Capacitively Coupled Plasma) driven by VHF (100 MHz) and LF (1 MHz) sources at each of electrodes has the plasma structure and characteristics appropriate for dielectric etching. That is, in a well designed 2f-CCP, VHF source is prepared to produce a high density plasma and LF source for a high energy ions incident on the wafer. We have confirmed that the radial variation of etch profile is mainly caused by the strong distortion of the surface potential at the wafer edge. In the present study, the influence of the geometry (width and height) and the dielectric constant of the focus ring in SiO@sub 2@ etching has been investigated in CF@sub 4@(5%)/Ar from the viewpoint of the ion velocity (energy and angle) distribution and the radical flux incident on the wafer as a function of radial position. The effective area of the wafer to be processed will be improved by the design of the interfacial physical structure between the surface and the bulk plasma.