AVS 47th International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS2-ThA

Paper PS2-ThA3
Control of Incident Fluxes and Surface Reactions in the Etching of Dielectric Materials

Thursday, October 5, 2000, 2:40 pm, Room 311

Session: Dielectrics I
Presenter: T. Tatsumi, Association of Super-Advanced Electronics Technologies (ASET), Japan
Authors: T. Tatsumi, Association of Super-Advanced Electronics Technologies (ASET), Japan
M. Matsui, Association of Super-Advanced Electronics Technologies (ASET), Japan
K. Kinoshita, Association of Super-Advanced Electronics Technologies (ASET), Japan
S. Kobayashi, Association of Super-Advanced Electronics Technologies (ASET), Japan
M. Sekine, Association of Super-Advanced Electronics Technologies (ASET), Japan
Correspondent: Click to Email
The relationship between SiO@sub 2@ etch rates and the incident flux of reactive species in dual-frequency (27/0.8 and 60/2 MHz) parallel-plate systems were evaluated by using various in-situ measurements tools, such as infrared IRLAS, QMS, and OES. The thickness of a C-F polymer layer on the etched SiO@sub 2@ surface was measured by XPS. The SiO@sub 2@ etch rate depends on both the total amount of F in the C-F reactive species and the ion energy at a reactive layer on the SiO@sub 2@ surface.@super 1@ The net energy supplied to the reactive layer depends on the total amount of ions, the acceleration energy of ions (assumed to be the peak-to-peak voltage, V@sub pp@), and the energy loss in the C-F polymer layer. The C-F polymer thickness increased when the incident flux of C-F species was relatively higher than the removal ability of C-F polymer, that mostly depends on oxygen flux. To vary the incident CF@sub x@ species, the C@sub 4@F@sub 8@ flow rate in the C@sub 4@F@sub 8@/Ar/O@sub 2@ was increased under 30mTorr of gas pressure and 1450 V of V@sub pp@. The ion flux was controlled by adjusting the RF powers. When we increased the ion flux from 3.0 x 10@super 16@ to 3.6 x 10@super 16@ cm@super -2@s@super -1@, the etch rate was increased because the energy on the reactive layer increased while the Si etch rate remained the same. Furthermore, the formation of the thick polymer (>1nm) started under higher C@sub 4@F@sub 8@ flow-rate conditions. This means the ability to remove excess C-F polymer on the etched surface was also improved. As a result the process-window of selective etching was increased. C@sub 5@F@sub 8@/Ar/O@sub 2@ gas chemistry was also evaluated in the same manner. An increase of C-concentration of the parent gas molecules induces the excess incidence of C atoms to the surface. As a result we mostly observed the C-F polymer deposition rate (not steady-state thickness) under high C@sub 5@F@sub 8@ flow-rate conditions. It is necessary to use the lower pressure or higher ion energy conditions to suppress the excess formation of the C-F polymer in the C@sub 5@F@sub 8@/Ar/O@sub 2@ process. @FootnoteText@ This work was supported by NEDO. @footnote 1@T.Tatsumi et al., J. Vac. Sci. Technol., A17 (1999) 1562.