Electric heating – Metal heating – By arc
Reexamination Certificate
1999-09-28
2001-02-27
Paschall, Mark (Department: 3742)
Electric heating
Metal heating
By arc
C156S345420, C204S298370, C204S298310, C118S7230MW
Reexamination Certificate
active
06194680
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a microwave plasma processing method and, more particularly, to a microwave plasma processing method suitable for processing using an ECR discharge.
A prior art microwave plasma processing method, such as a microwave plasma processing method disclosed in Japanese Patent Laid-open (Kokai) No. 60-154620, creates a magnetic field within a discharge tube with a solenoid, introduces a microwave into the discharge tube to produce a plasma within the discharge tube by the interactions of the magnetic field and the microwave and processes a workpiece with the plasma. When processing a workpiece with a plasma, this prior art microwave processing method varies the amplitude of the current flowing through the splenoid to vary the magnetic flux density of the magnetic field in order that a maximum plasma density region in the plasma density distribution oscillates between the central region and the peripheral region of the object surface of a workpiece to apply the plasma of a substantially uniform plasma density distribution to the object surface of the workpiece to improve the uniformity of processing.
This prior art is devised for nothing about the etch selectivity between the mask of the workpiece and an underlying layer, etch residue, a laminated film for the enhancement of the reliability of metal wiring lines and such. In this prior art, the density distribution of a plasma moves to the central portion or the peripheral portion of the object surface according to the gradient of the magnetic field and this prior art is not devised for the optimization of the plasma when the workpiece is changed. Therefore, it is difficult to determine process conditions capable of improving etch selectivity between the mask and the underlying layer and enabling processing without producing etch residue, when the prior art is applied to processing a workpiece having a minute configuration or to processing a laminated workpiece.
BRIEF SUMMARY OF THE INVENTION
Accordingly it is an object of the present invention to provide a microwave plasma processing method capable of etching a workpiece having a minute configuration or a laminated workpiece at a high etch selectivity between a mask and an underlying layer.
The object is achieved by a microwave plasma processing method that produces a plasma by exerting the actions of an electric field created by a microwave and a magnetic field created by a solenoid on a processing gas and processes a workpiece provided with a plurality of films of different materials with the plasma, comprising: controlling the magnetic field created by the solenoid so as to vary the distance between the surface to be processed of the workpiece and a resonance region according to the types of the films of the workpiece so that the position of the plasma produced by the actions of the electric field created by the microwave and the magnetic field created by the solenoid varies accordingly.
The etch selectivity between the film to be processed and the mask can be increased by creating a magnetic field created by the solenoid is controlled to form a resonance region in which the magnetic field and an electric field created by the microwave resonate with each other and varying the distance between the flat resonance region and the surface of the workpiece according to the type of the film to be processed so that the position of a plasma produced by the actions of the electric field created by the microwave and the magnetic field created by the solenoid is varied according to the type of the film to be processed. When etching the workpiece, the distance between the surface to be processed of the workpiece and the plasma is increased to prevent producing etch residue which is liable to be produced when the workpiece is etched, and the distance between the surface to be processed of the workpiece and the plasma is reduced when overetching the surface to be processed of the workpiece to enable etching the surface to be processed of the workpiece, suppressing the etching rate at which the underlying layer is etched.
REFERENCES:
patent: 5188717 (1993-02-01), Broadbent
patent: 5208512 (1993-05-01), Forster
patent: 5213658 (1993-05-01), Ishida
patent: 5245157 (1993-09-01), Ohiwa
patent: 5266154 (1993-11-01), Tatsumi
patent: 5354443 (1994-10-01), Moslehi
patent: 5478403 (1995-12-01), Shinagawa et al.
patent: 4107753 (1991-09-01), None
patent: 2244371 (1991-11-01), None
patent: 60-165620 (1985-08-01), None
patent: 9402959 (1994-02-01), None
Haikatak Eri
Sato Takashi
Watanabe Katsuya
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Paschall Mark
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