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A hot filament plasma etching method for etching semiconductor chips or other substrate surfaces at controlled rates and with controlled etch profiles uses the apparatus shown in the drawing.
English (United States)
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Triode System For Plasma Etching
A hot filament plasma etching method for etching semiconductor chips or
other substrate surfaces at controlled rates and with controlled etch profiles uses
the apparatus shown in the drawing.
The hot filament plasma etching system includes an evacuated chamber 10
having a filament electrode 12 facing an anode plate 14 and a third electrode 16
which supports the substrate 18 to be plasma etched. The filament 12 is heated
by current from an AC or DC power supply 13 so as to emit electrons. An
electrical discharge is generated and maintained by a DC power supply 15
connected between electrodes 12 and 14. The potential of the plasma relative to
the ground may be controlled by a power supply 17. The electrode 16 supporting
the substrate 18 can be moved into or out of the plasma.
A variable magnetic field, used to confine the plasma and spatially control the
relative number of charged to uncharged particles, is produced by electrical
current flowing through suitable coils 20. The electrode 18 is powered by an RF
or DC power supply 22.
A plasma etching gas such as CF(4) or a mixture such as CF(4) and O(2) is
admitted to the chamber 10, and a glow discharge is maintained primarily by the
application of a voltage between electrodes 12 and 14. The preferred operating
range of the reaction gas is between 1 micron and 100 microns.
The hot filament plasma etching system operates entirely at low voltage since
the hot filament discharge is chara...