Electric heating – Metal heating – By arc
Patent
1998-10-29
2000-07-11
Walberg, Teresa
Electric heating
Metal heating
By arc
219723MR, B23K 900
Patent
active
06087614&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a plasma processing system for processing a object to be treated, such as a semiconductor wafer, with a plasma.
BACKGROUND ART
Most wiring patterns of integrated circuits are formed of aluminum wiring lines, and there is a tendency for methods of forming a layer insulating film, such as a SiO.sub.2 film (silicon dioxide film) or a SiOF film (silicon oxide film containing fluorine), for insulating the aluminum wiring lines to employ an ECR (electron cyclotron resonance) plasma process because of the ability of the ECR plasma process to form films in a satisfactory quality.
Referring to FIG. 12 showing, by way of example, a conventional plasma processing system for carrying out the ECR plasma process, a 2.45 GHz microwave is propagated through a waveguide 11 into a plasma producing chamber 1A, a magnetic field of a predetermined magnetic field intensity, such as 875 G, is applied to the plasma producing chamber 1A by a solenoid 12 to produce a high-density plasma from a plasma producing gas 15, such as Ar gas and O.sub.2 gas, by the interaction (resonance) of the microwave and the magnetic field, a reactive gas 16, such as SiH.sub.4 gas or SiF.sub.4 gas, supplied to a film forming chamber 1B is activated and ionized by the plasma, and a thin film is deposited on the surface of a semiconductor wafer W placed on a wafer stage 13.
As shown by way of example in FIG. 13, the waveguide 11 is formed by connecting a conical waveguide section 11b to the lower end of a rectangular waveguide section 11a having a bend therein for transmitting a transverse electric wave in a TE.sub.11 mode (hereinafter referred to simply as "TE mode"). The lower end of the conical waveguide section 11b is joined to the upper end of a vessel defining the plasma producing chamber 1A. When a microwave is generated by a microwave generator 14 connected to the other end of the rectangular waveguide section 11a, the microwave is propagated in a TE mode in the waveguide 11 to the plasma producing chamber 1A. When the rectangular end of the bent rectangular waveguide section 11a is connected to the circular upper end of the conical waveguide section 11b, the microwave propagated in a TE mode in the rectangular waveguide section 11a is propagated also in a TE mode in the conical waveguide section 11b.
The propagation of the microwave in a TE mode in a cylindrical waveguide of an inside diameter 2a will be described with reference to FIGS. 14A and 14B. FIG. 14A is a cross-sectional view, and FIG. 14B is a sectional view taken on line A--A in FIG. 14A. In FIG. 14A, solid lines represent an electric field, and broken lines represent a magnetic field. In FIG. 14B, blank circles .smallcircle. indicate a direction of an electric field into the paper, and solid circles .circle-solid. indicate a direction of an electric field out of the paper. In a TE mode, the electric field is parallel to the diameter of the conical waveguide, and .lambda.=3.41a, where .lambda. is the wavelength of the microwave, and a is the radius of the cylindrical waveguide.
As is obvious from FIG. 14A, the density of lines of electric force is high in a central region and decreases toward a peripheral region if the microwave is guided in a TE mode into the plasma producing chamber 1A by the foregoing waveguide. Therefore the field intensity in the peripheral region is lower than that of the central region and hence the distribution of field intensity of the electric field is not uniform. Consequently, the density of a plasma produced by the agency of the microwave is low in the peripheral region and hence it is difficult to deposit a film on the surface of the wafer in a highly uniform thickness. Incidentally, the importance of the high uniformity of a film formed on the surface of a wafer has increased because pattern miniaturization has a tendency to advance in recent years.
A plasma processing system disclosed in U.S. Pat. No. 5,234,526 uses a TM.sub.01 mode. This plasma processing system employs a waveguide formed by connect
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Aoki Takeshi
Ishizuka Shuichi
Nakase Risa
Tokyo Electron Limited
Van Quang
Walberg Teresa
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