JP4188004B2 - Plasma processing apparatus and variable power distributor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus for processing an object to be processed by plasma generated by introducing a microwave into a process gas, and a variable power distributor for controlling the power of the introduced microwave.
[0002]
[Prior art]
There is a plasma processing apparatus as an apparatus for performing dry etching, ashing, or the like on an object to be processed such as a silicon wafer for manufacturing a semiconductor or a glass substrate for various displays. One such plasma processing apparatus is a microwave plasma apparatus. The processing by this microwave plasma apparatus is performed as follows. First, an object to be processed is accommodated in a processing chamber capable of maintaining a vacuum, and a low-pressure process gas of, for example, about 1 to 1000 Pa is supplied thereto. Then, the microwave from the microwave generator driven by the power source is introduced into the processing chamber. At this time, the process gas is partially ionized and decomposed by irradiation of the process gas with microwaves, and the object to be processed can be processed with ions and radicals generated thereby.
[0003]
By the way, in the microwave plasma apparatus as described above, the most frequently used method for introducing microwaves into the processing chamber is to make all or part of the walls of the processing chamber out of a dielectric, and from there the micro It is a method of introducing waves. Here, when a part of the wall of the processing chamber is made of a dielectric, the dielectric part of the wall is called a “window”. When designing the processing chamber, it is possible to realize plasma and processing speed space distribution control suitable for the object to be processed and the processing process by optimizing the number, position, shape and size of the windows.
[0004]
[Problems to be solved by the invention]
However, even if the window structure is optimized as described above, the result may vary greatly depending on process parameters such as pressure in the processing chamber and gas components. In addition, when a window structure intended for one processing process is adopted, it is not always compatible with other processing processes.
[0005]
In order to cope with this, there is also a method of changing the structure in the processing chamber according to the processing process. For example, it is conceivable that an installation table on which the object to be processed is placed is movably provided, and the distance between the object to be processed and the window is changed according to the processing process. However, it is difficult to change the structure of the processing chamber in which a vacuum is to be maintained, and the target plasma and processing speed space distribution may not be achieved only by changing the distance between the workpiece and the window.
[0006]
It is also conceivable to control the plasma and the processing speed space distribution by providing independent microwave generators and power sources in a plurality of windows and independently controlling the power of these microwave generators. However, since the microwave generator is expensive, it is difficult to commercialize a product that is installed independently according to a plurality of windows at the present stage.
[0007]
The present invention has been proposed to solve the above-described problems of the prior art, and its purpose is to realize plasma and processing speed space distribution control at low cost without changing the structure of the processing chamber. An object of the present invention is to provide a plasma processing apparatus and a variable power distributor.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is characterized in that a processing chamber capable of accommodating an object to be processed and having a window for introducing a microwave, and a microwave for plasma generation supplied from a microwave oscillator are provided. A plasma processing apparatus comprising a waveguide body that is introduced into the processing chamber through a window, wherein a plurality of the windows are provided, and a variable power distributor that distributes the microwave power from the microwave oscillator to a plurality of windows. And the waveguide communicated between the variable power distributor and the processing chamber has a plurality of microwave supply paths corresponding to the plurality of microwave powers distributed by the variable power distributor. and, wherein the plurality of windows, a central window, made near a window provided on its periphery, the waveguide comprises a microwave supply path to the central window, a microwave supply path to said peripheral windows There comprises a dual wave guide, which is divided, the variable power divider is connected to the dual waveguide coaxially and consists of a part of the dual wave guide, the variable power distribution Oite inside the vessel, characterized in that the power of the microwave distribution, at least one closing member for controlling for each of the plurality of microwave supply path is provided inside the dual waveguide And
The invention according to claim 2 is provided in communication with a plurality of microwave supply paths connected to a central window in the processing chamber of the plasma processing apparatus and peripheral windows provided around the central window. In the variable power distributor that distributes the power of the microwave to the plurality of supply paths, the plurality of supply paths include a microwave supply path to the central window and a microwave supply path to the peripheral window And the variable power distributor is connected to the double waveguide coaxially and is constituted by a part of the double waveguide to distribute the microwaveguide. At least one open / close member for controlling wave power for each of the plurality of supply paths is provided inside the double waveguide .
In the inventions according to the first and second aspects as described above, the variable power distributor can control the distribution of the microwave power supplied from the plurality of windows into the processing chamber. By changing the wave power ratio, it is possible to realize plasma and processing speed space distribution according to the object to be processed and the processing process.
[0009]
In addition, by providing a central window and surrounding peripheral windows, the microwave introduction region can be widened, so that a large area plasma treatment is possible and a uniform treatment is facilitated. .
[0010]
Further, since the supply of microwaves can be controlled separately for the central window and the peripheral window, the plasma density and the processing speed can be changed between the center and the periphery of the processing chamber.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention (hereinafter referred to as an embodiment) will be specifically described with reference to FIGS.
[Configuration of Embodiment]
〔overall structure〕
As shown in FIG. 1, the plasma processing apparatus of this embodiment includes a processing chamber 1, a double waveguide 2, a microwave generator 3, a variable power distributor 4, an automatic impedance tuner 5, and the like. The processing chamber 1 is a container capable of maintaining a vacuum, and is configured such that an exhaust pump (not shown) and a gas supply source are connected to maintain a gas atmosphere having a predetermined composition and pressure. In the processing chamber 1, an installation table 6 for placing the workpiece A is provided.
[0012]
A central window 7 and a peripheral window 8 for introducing microwaves are provided in the upper part of the processing chamber 1. For example, as shown in FIG. 2, the central window 7 and the peripheral window 8 have a circular central window 7 provided on the axis of the processing chamber 1 and a plurality of circular peripheral windows 8 a around the central window 7. As shown in FIG. 3, a ring-shaped peripheral window 8b is provided coaxially with the central window 7, and a plurality of arc-shaped peripheral windows 8c are arranged around the central window 7 as shown in FIG. Although things can be considered, it is not limited to these.
[0013]
Moreover, as a dielectric material for forming the central window 7 and the peripheral windows 8, 8a to 8b, for example, quartz, alumina, sapphire, aluminum nitride, or the like can be used. It is not limited.
[0014]
The double waveguide 2 is a tube for supplying microwaves to the processing chamber 1 through the central window 7 and the peripheral window 8 of the processing chamber 1, and an inner tube 2 a serving as a supply path to the central window 7. And the outer tube 2b serving as a supply path to the peripheral window 8. The microwave generator 3 is a device that is driven by a power source (not shown) to generate and supply a microwave. The variable power distributor 4 controls the supply of microwaves to the central window 7 and the peripheral window 8 with a configuration described later. The automatic impedance tuner 5 is a matching unit that is connected between the microwave generator 3 and the variable power distributor 4 via a waveguide, and automatically matches the impedance changed by the operation of the variable power distributor 4. is there.
[0015]
[Configuration of variable power distributor]
Here, a specific configuration example of the variable power distributor 4 will be described. That is, as shown in FIG. 5, the variable power distributor 4 is provided with an introduction part 4a into which microwaves from the microwave generator 3 and the automatic impedance tuner 5 are introduced inside the waveguide. A path branched from 4a into a central path 4b communicating with the inner pipe 2a of the double waveguide 2 and a peripheral path 4c communicating with the outer pipe 2b is formed.
[0016]
A metal first opening / closing member 4d for controlling the opening / closing amount of the central path 4b is provided in the introduction portion 4a so as to be movable by a driving mechanism (not shown). Further, in the peripheral path 4c, a metal ring-shaped second opening / closing member 4e for controlling the opening / closing amount of the path is movably provided by a drive mechanism (not shown) at a portion where the inner diameter is enlarged.
[0017]
[Effects of the embodiment]
The operation of the present embodiment as described above is as follows. That is, as shown in FIG. 1, the workpiece A is placed on the installation table 6, and a low-pressure process gas is introduced into the processing chamber 1 from the gas supply source. Then, the microwave from the microwave generator 3 is processed from the central window 7 and the peripheral window 8 through the automatic impedance tuner 5, the variable power distributor 4 and the double waveguide 2 as shown in FIG. It is introduced into the chamber 1. As described above, in the present embodiment, the microwave power is separated and supplied to the central window 7 side and the peripheral window 8 side by the inner tube 2 a and the outer tube 2 b in the double waveguide 2. As a result, plasma P is generated in the processing chamber 1 and the object A is processed.
[0018]
At this time, the first opening / closing member 4d and the second opening / closing member 4e in the variable power distributor 4 are moved, pass through the central path 4b and the inner tube 2a, and supplied to the processing chamber 1 from the central window 7. By controlling the ratio of the wave power and the microwave power supplied from the peripheral window 8 into the processing chamber 1 through the peripheral path 4c and the outer tube 2b, the plasma and processing velocity space distribution in the processing chamber 1 is controlled. Control.
[0019]
For example, when the power of the microwave supplied to the central window 7 is increased, the plasma density and the processing speed at the center of the processing chamber 1 are increased, and when the power of the microwave supplied to the peripheral window 8 is increased, the processing chamber 1 is increased. The peripheral plasma density and the processing speed increase. As described above, when the microwave power is changed by the variable power distributor 4, the impedance changes. However, the impedance matching is performed by the automatic impedance tuner 5 provided between the microwave generator 3 and the variable power distributor 4. Is retained.
[0020]
[Effect of the embodiment]
According to the present embodiment as described above, the power ratio of the microwaves supplied from the single microwave generator 3 into the processing chamber 1 through the central window 7 and the peripheral window 8 is changed to the variable power distributor 4. Therefore, without changing the structure in the processing chamber 1, plasma and processing speed space distribution suitable for the workpiece A and the processing process can be realized at low cost.
[0021]
In addition, the combination of the central window 7 and the peripheral window 8 makes it possible to widen the microwave introduction region, so that a large-area plasma process can be performed and the process can be made uniform or localized. Is also easier.
[0022]
Furthermore, since the microwave is supplied through the double waveguide 2, the power of the microwave supplied to the inner tube 2a side and the outer tube 2b side is changed, and the center and the periphery of the processing chamber 1 are Plasma density and processing speed can be changed.
[0023]
[Other Embodiments]
The present invention is not limited to the embodiment as described above, and the shape, number, arrangement, material, size, and the like of each member can be appropriately changed. For example, in the above embodiment, the drive mechanisms of the first opening / closing member 4d and the second opening / closing member 4e may be driven independently or integrally. Further, for example, as shown in FIG. 6, it is possible to configure only the first opening / closing member 4d or as shown in FIG. 7 only the second opening / closing member 4e (4d is fixed). It is.
[0024]
In addition, the inner tube 2a of the double waveguide 2 in the above-described embodiment requires a certain diameter (about 0.6 times or more of the wavelength) of the inner tube 2a in relation to the wavelength of the microwave. Since the inner tube 2a is a coaxial cable, the diameter can be reduced while ensuring the supply of microwaves.
[0025]
The shape of the processing chamber of the present invention, the shape, number and position of the windows provided in the processing chamber, the waveguide for supplying microwaves, the shape, number and type of the waveguide are also exemplified in the above embodiment. It is not limited to things. Further, the plasma source may be an apparatus without an installation table. Further, the structure and material of the variable power distributor are not limited to those exemplified in the above embodiment. For example, the waveguide and the double waveguide constituting the variable power distributor may be integrally formed continuously. In addition, for example, by providing a waveguide for each individual window, or using a variable power distributor that can open and close a valve for each individual window, the microwave supply can be controlled for each individual window. Also good. Further, in the double waveguide, the inner diameter and the outer diameter may be different materials.
[0026]
Further, a plurality of plasma generators may be provided so as not to increase the cost. Furthermore, the process gas used in the present invention, the object to be processed, etc. are not limited to specific ones, and ions, radicals, etc. in the plasma responsible for processing are optimized according to the object to be processed. .
[0027]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a plasma processing apparatus and a variable power distributor capable of realizing plasma and processing speed space distribution control at low cost without changing the structure of the processing chamber.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of a plasma processing apparatus of the present invention.
FIG. 2 is a longitudinal sectional view showing an example of a window shape of a processing chamber in the embodiment of FIG.
3 is a longitudinal sectional view showing an example in which the peripheral window of the processing chamber in the embodiment of FIG. 1 is ring-shaped.
4 is a longitudinal sectional view showing an example in which the peripheral window of the processing chamber in the embodiment of FIG. 1 is formed in an arc shape.
FIG. 5 is a longitudinal sectional view showing an example of a variable power distributor in the embodiment of FIG.
FIG. 6 is a longitudinal sectional view showing another example of the variable power distributor in the embodiment of the present invention.
FIG. 7 is a longitudinal sectional view showing another example of the variable power distributor in the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Processing chamber 2 ... Double waveguide 2a ... Inner tube 2b ... Outer tube 3 ... Microwave generator 4 ... Variable power distributor 4a ... Introduction part 4b ... Center path 4c ... Peripheral path 4d ... First opening / closing member 4e ... second opening / closing member 5 ... automatic impedance tuner 6 ... installation base 7 ... central windows 8, 8a to 8c ... peripheral window A ... workpiece P ... plasma

Claims (2)

A processing chamber capable of accommodating an object to be processed and having a window for introducing a microwave, and a waveguide for introducing a microwave for plasma generation supplied from a microwave oscillator into the processing chamber through the window. In the plasma processing apparatus provided,
A plurality of the windows are provided,
A variable power distributor that distributes the microwave power from the microwave oscillator to a plurality of parts,
The waveguide communicated between the variable power distributor and the processing chamber has a plurality of microwave supply paths corresponding to a plurality of microwave powers distributed by the variable power distributor,
The plurality of windows are composed of a center window and peripheral windows provided around the center window.
The waveguide includes a double waveguide in which a microwave supply path to the central window and a microwave supply path to the peripheral window are divided.
The variable power distributor is coaxially connected to the double waveguide, and is configured by a part of the double waveguide.
Oite inside of the variable power divider, the power of the microwave distribution, at least one closing member for controlling for each of the plurality of microwave supply path, provided inside the dual waveguide A plasma processing apparatus. Provided in communication with a plurality of microwave supply paths that communicate with a central window in the processing chamber of the plasma processing apparatus and peripheral windows provided around the central window, and the microwave power from the microwave oscillator In the variable power distributor that distributes to the supply path,
The plurality of supply paths include a double waveguide in which a microwave supply path to the central window and a microwave supply path to the peripheral window are divided.
The variable power distributor is coaxially connected to the double waveguide, and is configured by a part of the double waveguide.
The variable power distributor, wherein at least one open / close member that controls the power of the microwave to be distributed for each of the plurality of supply paths is provided inside the double waveguide .

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