JP2000012290A - Plasma treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize plasma generating in a treating chamber with an electromagnetic field rotating with a circularly polarized wave by supplying the circularly polarized wave in a wave guide for supplying a high frequency power to a treating chamber through the circularly polarized wave. SOLUTION: A microwave generated with a microwave power source 101 is transmitted to a mode converter 104 with a square wave guide tube 105 through an isolator 102 and a matching device 103. A microwave is introduced into a cylindrical cavity part 107 through a circular wave guide tube 106. A plasma treating chamber 109 separated with a microwave introducing window is installed in the lower part of the cylindrical cavity part 107. In the mode converting device 104, an input side wave guide tube is a square guide wave tube, and an output side wave guide tube is a circular wave guide tube. A circular, rectangular conversion corner and a circularly polarized wave generator are connected to between them. By using the circularly polarized wave generator, since a microwave electromagnetic field is rotated in poin of time, plasma generated is made uniform in the angle direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION In the manufacture of semiconductor integrated circuits and the like, a plasma processing apparatus is used for forming and processing a film. The present invention provides a plasma processing apparatus that enables high-quality plasma processing by uniformly generating more stable plasma.

2. Description of the Related Art In an ordinary plasma processing apparatus, a gas suitable for processing is supplied into a processing chamber at a predetermined flow rate, and the pressure in the processing chamber is controlled to a pressure suitable for processing by adjusting the exhaust speed of the gas. Is done. Further, an electromagnetic wave is supplied into the processing chamber to generate plasma, and plasma processing is performed. This plasma is generated in a distribution corresponding to the electromagnetic field distribution in the processing chamber. The distribution of the electromagnetic field in the plasma is determined by the method of supplying the electromagnetic waves, plasma characteristics such as the density and pressure of the plasma, and the shape of the processing chamber.

In the above-mentioned conventional plasma processing apparatus, there is a problem that the electromagnetic field distribution in the plasma is not sufficiently considered, and the control of the plasma distribution is not always properly performed. . An object of the present invention is to provide a plasma processing apparatus that can make the power distribution of an electromagnetic wave supplied to a processing chamber more uniform.

The above objects can be attained by adjusting the power distribution of electromagnetic waves in plasma. That is, a feature of the present invention is that a high-frequency power is supplied to a processing chamber via a waveguide, a plasma is generated in the processing chamber by the high-frequency power, and a sample in the processing apparatus is plasma-processed. In a processing apparatus, a circularly polarized wave generator is interposed in the waveguide that supplies high-frequency power to the processing chamber, and a circularly polarized wave is supplied into the processing chamber.
With the above configuration, the high-frequency power supplied to the processing chamber can be circularly polarized. Therefore, the plasma generated in the processing chamber can be made more uniform by using an electromagnetic field rotated by circularly polarized waves.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a plasma processing apparatus using the present invention. For example, a microwave having a frequency of, for example, 2.45 GHz generated by a microwave source 101 such as a magnetron or the like is supplied to the isolator 10 by a rectangular waveguide 105.
2. The signal is transmitted to the mode converter 104 via the matching unit 103. The microwave is further introduced into the cylindrical cavity 107 via the circular waveguide 106. A plasma processing chamber 10 separated by a microwave introduction window 108 is provided below the cylindrical cavity.
There are nine. A gas introduction system and a vacuum exhaust system (not shown) are connected to the plasma processing chamber 109, and the inside of the processing chamber 109 is maintained at a gas atmosphere and pressure suitable for plasma processing. In the plasma processing chamber 109, a substrate electrode 110 for setting the substrate 111 to be processed is provided. Mode converter 1
2 is shown in FIG. The input waveguide 201 is a rectangular waveguide, and the output waveguide 202 is a circular waveguide.
Between them, the circular / rectangular conversion corner 204 and the circular polarization generator 20
3 are connected. Although the mode converter shown in FIG. 2 uses a circular-rectangle conversion corner, a simple circular-rectangle converter may be used. Here, circular polarization will be briefly described.
In electromagnetic waves such as microwaves, a plane formed by an electric field vector and a vector in the traveling direction of the electromagnetic wave is called a plane of polarization. Circularly polarized waves refer to electromagnetic waves whose polarization plane rotates at the frequency of the waves.
FIG. 3 shows a TE11 mode electric field distribution which is a fundamental mode of the circular waveguide. The electric field vector 302 is perpendicular to the inner wall of the circular waveguide 301. Assume that a coordinate system having an origin at the center of the circular waveguide as shown in FIG. When the electromagnetic field of the TE11 mode is circularly polarized, the electromagnetic field is rotated with time. Various configurations for generating circularly polarized waves have been proposed, for example, as described in “Electronic Information and Communication Handbook (Ohm, edited by the Institute of Electronics, Information and Communication Engineers, 1990)”. Can be used. FIG. 4 shows the electric field distribution at the connection between the circular waveguide 106 and the cylindrical cavity 107 shown in FIG. It is assumed that the circular TE11 mode shown in FIG. 3 is incident on the mode converter microwave electromagnetic field without using the circular polarization generator 203, and a cross section corresponding to the yz plane in FIG. 3 will be described first. At the connection between the circular waveguide 106 and the cylindrical cavity 107, the diameter of the cylinder expands stepwise, so that a plurality of modes other than the incident TE11 mode are generated. Cylindrical cavity 107,
Although depending on the size of the circular waveguide 106 and the like, the electric field concentrates on the edge of the connection portion, and the electric field vector 4 shown in FIG.
01 tends to be distributed. FIG. 5 schematically shows an example of the distribution in the xy plane of the plasma generated when the electric field distribution shown in FIG. A so-called "saddle-shaped" distribution tends to have a convex distribution in the x-axis direction and a concave distribution in the y-axis direction. Therefore, the uniformity of the plasma processing performed on the substrate to be processed also tends to have a “saddle” distribution.
However, the use of the circularly polarized wave generator 203 causes the microwave electromagnetic field to rotate with time, so that the generated plasma is more uniform in the angular direction. Therefore,
The uniformity of the plasma processing can be greatly improved.
Even if a static magnetic field is applied to the plasma processing chamber 109, the uniformity of the plasma can be significantly improved in the same manner. In this case, since the propagation characteristics of the electromagnetic wave in the plasma to which the static magnetic field is applied are different depending on the relationship between the direction of the static magnetic field and the rotational direction of the circularly polarized wave, the effect may be different depending on the rotational direction of the circularly polarized wave. When a static magnetic field that causes an electron cyclotron resonance phenomenon is applied to the plasma processing chamber 109, circularly polarized waves that rotate clockwise in the direction of the static magnetic field are strongly absorbed by plasma by electron cyclotron resonance. On the other hand, circularly polarized waves rotating counterclockwise are not strongly absorbed in the plasma. In either case, there is an effect of plasma uniformization by circular polarization, but since the plasma distribution is different between the two,
In order to perform uniform plasma processing, it is necessary to optimize the positional relationship between the plasma generation position and the substrate to be processed.
When a static magnetic field is not applied to the plasma processing chamber, it is not necessary to consider the direction of rotation of the circularly polarized wave.

As is apparent from the above description, according to the present invention, the high-frequency power supplied to the processing chamber can be circularly polarized, and the plasma generated in the processing chamber is rotated by the circularly polarized wave. More uniformity can be achieved by using an electromagnetic field. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a mode converter.

FIG. 3 is a diagram showing a TE11 mode electric field distribution in a circular waveguide.

FIG. 4 is a diagram showing a distribution of an electric field near a connection between a circular waveguide and a cylindrical cavity.

FIG. 5 is a diagram illustrating an example of a plasma distribution when circular polarization is not used.

[Explanation of symbols]

101: microwave source, 102: isolator, 103
... matching device, 104 ... mode converter, 105 ... rectangular waveguide, 106 ... circular waveguide, 107 ... cylindrical cavity, 108
... microwave introduction window, 109 ... plasma processing chamber, 110
... substrate electrode, 111 ... substrate to be processed, 201 ... input side waveguide, 202 ... output side waveguide, 203 ... circular polarization generator, 2
04: circular rectangular conversion corner, 301: circular waveguide, 302
... electric field vector, 401 ... electric field vector.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Masahiro Tsunoya 794, Higashi-Toyoi, Kazamatsu-shi, Yamaguchi Prefecture F-term in the Kasado Plant of Hitachi, Ltd.

Claims (4)

[Claims] 1. A plasma processing apparatus for supplying high-frequency power to a processing chamber via a waveguide, generating plasma in the processing chamber with the high-frequency power, and performing plasma processing on a sample in the processing apparatus. A plasma processing apparatus, wherein a circularly polarized wave generator is interposed in the waveguide that supplies high-frequency power to a chamber, and circularly polarized waves are supplied into the processing chamber. 2. The plasma processing apparatus according to claim 1, wherein the waveguide is formed of a waveguide having an axially symmetric structure for transmitting high-frequency power, and the processing chamber has a substantially columnar structure connected to the waveguide. A plasma generating chamber connected to the cavity and having a structure for holding a substrate to be processed therein, wherein the processing chamber includes a gas supply device for supplying a processing gas to the plasma generating chamber. A plasma processing apparatus comprising an exhaust device for maintaining the plasma generation chamber at a predetermined pressure suitable for processing. 3. The plasma processing apparatus according to claim 2, further comprising a magnetic field generator for applying a static magnetic field to the plasma generation chamber. 4. The plasma processing apparatus according to claim 2, wherein a magnetic field is effectively absent near the substrate to be processed.