JP2000173989A - Plasma treating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treating apparatus wherein even if a reactor has a large diameter, the total apparatus size can be possibly reduced, it can be installed in a space, the directivity of ions incident on a work can be improved and the reactor life can be prolonged. SOLUTION: The plasma treating apparatus comprises an annular waveguide type antenna 11a formed at a part facing an annular microwave window 4 of a block 25 and slits 15 bored in a plate 16. A counter electrode 18 is fitted into a recess formed in the bottom center of a heating block 26 and electrically grounded. On the bottom face of the counter electrode 18 a dielectric is deposited in the form of a pattern of inductors 18a equally distributed with center at the counter electrode 18, with sectorial electrodes 18b each formed between the adjacent inductors 18a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for performing processing such as etching or ashing on a semiconductor substrate, a glass substrate for a liquid crystal display, or the like by using plasma generated by using microwaves.

[0002]

2. Description of the Related Art Plasma generated by giving energy to a reaction gas from the outside is widely used in a manufacturing process of an LSI or an LCD. In particular, the use of plasma has become an indispensable basic technology in the dry etching process. As the size of a substrate processed by the plasma increases, it is required to uniformly generate the plasma over a wider area. Therefore, the applicant of the present application has disclosed Japanese Patent Application Laid-Open Nos. 62-5600 and 62-9948.
The following device is proposed in Japanese Patent Publication No. 1 and the like.

[0003] FIG. 8 is a Japanese Patent Application Laid-Open No. 62-5600 and
FIG. 9 is a side sectional view showing a plasma processing apparatus of the same type as the apparatus disclosed in JP-A-62-99481, and FIG. 9 is a plan view of the plasma processing apparatus shown in FIG. Rectangular box-shaped reactor 31
Is formed entirely of aluminum. Reactor
A microwave window 34 is arranged on the upper part of the reactor 31, and the upper part of the reactor 31 is hermetically sealed by the microwave window 34. The microwave window 34 is formed of a dielectric material such as quartz glass or alumina, which has heat resistance and microwave permeability and has a small dielectric loss.

[0004] A rectangular box-shaped cover member 40 for covering the upper part of the reactor 31 is connected to the reactor 31. A dielectric line 41 is attached to a ceiling portion in the cover member 40.
The dielectric line 41 is formed by molding a dielectric such as a fluororesin such as Teflon (registered trademark), a polyethylene resin, or a polystyrene resin into a plate shape having a protrusion at a vertex of a substantially pentagon formed by combining a rectangle and a triangle. The projection is fitted inside a waveguide 51 connected to the peripheral surface of the cover member 40. The microwave oscillator 50 is connected to the waveguide 51, and the microwave oscillated by the microwave oscillator 50 is incident on the projection of the dielectric line 41 by the waveguide 51.

As described above, the base end side of the convex portion of the dielectric line 41 is formed into a tapered portion 41a having a substantially triangular shape in plan view, and the microwave incident on the convex portion follows the tapered portion 41a. And is spread in the width direction thereof and propagates throughout the dielectric line 41. The microwave is reflected at the end face of the cover member 40 facing the waveguide 51, and the incident wave and the reflected wave are superimposed to form a standing wave on the dielectric line 41.

[0006] The interior of the reactor 31 is a processing chamber 32,
A required gas is introduced into the processing chamber 32 from a gas introduction pipe 35 fitted in a through hole penetrating the peripheral wall of the processing chamber 32. At the center of the bottom wall of the processing chamber 32, a mounting table 33 for mounting the workpiece W thereon.
An RF power supply 37 of several hundred kHz to several tens of MHz is connected to the mounting table 33 via a matching box 36. An exhaust port 38 is provided in the bottom wall of the reactor 31 so that the inside air of the processing chamber 32 is exhausted from the exhaust port 38.

In order to perform an etching process on the surface of the processing object W using such a plasma processing apparatus, the inside of the processing chamber 32 is evacuated to a desired pressure by exhausting the gas through an exhaust port 38, and then a gas introduction pipe 35 is formed. To supply the reaction gas into the processing chamber 32. Next, a microwave is oscillated from the microwave oscillator 50 and introduced into the dielectric line 41 via the waveguide 51. At this time, the microwave is uniformly spread in the dielectric line 41 by the tapered portion 41a, and a standing wave is formed in the dielectric line 41.
Due to this standing wave, a leaked electric field is formed below the dielectric line 41, and this is transmitted through the microwave window 34 and introduced into the processing chamber 32. In this way, the microwave is applied to the processing chamber 32.
Propagate inside. As a result, plasma is generated in the processing chamber 32, and the surface of the workpiece W is etched by the plasma. Thereby, even if the diameter of the reactor 31 is increased in order to process the large-diameter workpiece W, the microwave can be uniformly introduced to the entire region of the reactor 31 and the large-diameter workpiece W can be relatively uniformly plasma-processed.

[0008]

In the conventional plasma processing apparatus, in order to spread the microwave uniformly on the dielectric line 41, the microwave is projected horizontally from the microwave window 34 and the edge of the reactor 31. A tapered portion 41a is provided, and the tapered portion 41a is set to a predetermined size in accordance with the area of the dielectric line 41, that is, the diameter of the processing chamber 32. Therefore, when installing a conventional plasma processing apparatus, an extra horizontal space for accommodating the tapered portion 41a protruding from the peripheral edge of the reactor 31 must be secured.

By the way, as the diameter of the sample W increases, a plasma processing apparatus having a larger diameter of the reactor 31 is required. At this time, it is also required that the installation place of the apparatus need not be treated, that is, it can be installed in a space as narrow as possible. However, in the conventional apparatus, since the size of the tapered portion 41a is determined according to the diameter of the reactor 31, there is a problem that both of the above requirements cannot be satisfied.

Further, in the conventional plasma processing apparatus, for example, the peripheral wall of the reactor 31 is grounded so as to serve as the counter electrode of the mounting table 33 to which a high frequency is applied. Because the ions collide and cause damage, the reactor 31
Life is short. Further, when the peripheral wall of the reactor 31 is grounded,
In some cases, the bias potential generated on the surface of the mounting table 33 is insufficient. In this case, the directivity of ions incident on the workpiece W may be deteriorated, and process characteristics such as anisotropy may be reduced. .

The present invention has been made in view of such circumstances, and an object thereof is to reduce the size of the entire apparatus as much as possible even if the diameter of the reactor is large, and to install the apparatus in a small space. It is another object of the present invention to provide a plasma processing apparatus capable of improving the directivity of ions incident on an object to be processed and extending the life of a reactor.

[0012]

According to a first aspect of the present invention, there is provided a plasma processing apparatus comprising: a container in which a mounting table on which an object to be processed is mounted is provided; a counter electrode disposed to face the mounting table; An annular microwave window externally fitted to the electrode, and an annular waveguide antenna that is disposed to face the microwave window and emits microwaves to the microwave window; An apparatus for transmitting the microwave window, introducing microwaves into a container to generate plasma, applying a high frequency to the mounting table, and processing the object by the generated plasma, wherein the counter electrode A guide portion for guiding microwaves introduced into the container is provided on a surface facing the mounting table.

[0013] A plasma processing apparatus according to a second aspect of the present invention comprises:
In the invention, the guide portion is formed of a dielectric.

[0014] A plasma processing apparatus according to a third aspect of the present invention comprises:
Alternatively, in the second invention, the guide portion is substantially uniformly arranged around a central axis of the counter electrode.

A plasma processing apparatus according to a fourth aspect of the present invention has a first
In any one of the third to third aspects, the counter electrode is formed of a silicon-based material.

According to a fifth aspect of the present invention, there is provided a plasma processing apparatus comprising:
In any one of the fourth to fourth inventions, an endless annular waveguide antenna is provided.

A plasma processing apparatus according to a sixth aspect of the present invention has a first
In any one of the fourth to fourth inventions, a terminated ring-shaped waveguide antenna is provided.

A plasma processing apparatus according to a seventh aspect of the present invention has
In the present invention, the waveguide antenna is formed in a C shape or a spiral shape.

In the plasma processing apparatus of the present invention, since the microwave is inserted into the container by the endless annular or end annular waveguide type antenna arranged opposite to the microwave window, the dielectric line is formed. Even if there is no portion that spreads the microwave uniformly, such as a tapered portion provided in the annular configuration of the slit from which the microwave is radiated, that is, the diameter of the annular waveguide antenna, the shape and arrangement of the slit, Further, by considering the cross-sectional shape of the waveguide and the propagation mode of the microwave, the microwave can be supplied into the container so that the plasma is uniformly generated. Therefore, there is no projecting portion such as a tapered portion provided on the dielectric line, and the size of the plasma processing apparatus can be reduced as much as possible.

On the other hand, since the counter electrode disposed opposite to the mounting table for applying the high frequency can act as a ground electrode for the high frequency applied to the mounting table, ions in the plasma collide with the inner peripheral surface of the container. Damage is prevented and the life of the container can be extended. In addition, since a bias potential can be stably generated on the mounting table, ions in the plasma are substantially perpendicularly incident on the object to be processed, and process characteristics such as anisotropy can be improved.

Further, the microwave introduced through the microwave window and introduced into the container is guided immediately below the counter electrode by a guide portion provided on one or a plurality of portions of the surface of the counter electrode facing the mounting table. I do. As a result, an electric field is formed in substantially the entire region facing the annular microwave window and the counter electrode inside the container, and plasma having a substantially uniform density is generated in a plane parallel to the mounting table. Therefore, the process characteristics are further improved.

In the plasma processing apparatus according to the third aspect of the present invention, since the plurality of guide portions are disposed substantially evenly around the center axis of the counter electrode, the microwave is applied substantially directly below the counter electrode. The plasma can be guided by the intensity, and a plasma having a substantially uniform density can be generated immediately below the counter electrode.

When a silicon oxide film is etched using a fluorocarbon-based reaction gas (C _x F _y gas), the plasma dissociates the C _x F _y gas to generate fluorine molecules (F or F ₂ ). There is a possibility that the etching rate of the silicon oxide film is relatively reduced with respect to the etching rate of the resist.

However, in the plasma processing apparatus according to the fourth aspect of the invention, since the counter electrode is formed of a silicon-based material, the fluorine molecules react with the counter electrode and react with SiF _4.
As a result, the fluorine molecules are selectively removed. As a result, the etching rate of the silicon oxide film with respect to the etching rate of the resist is improved, and etching with a high selectivity can be performed. Further, the counter electrode formed of a silicon-based material also has an advantage that there is little problem of contamination.

[0025]

Embodiments of the present invention will be specifically described below with reference to the drawings. (Embodiment 1) FIG. 1 is a side sectional view showing a structure of a plasma processing apparatus according to the present invention, and FIG. 2 is a plan view of the plasma processing apparatus shown in FIG. Bottomed cylindrical reactor 1
Is formed entirely of a metal such as aluminum. At the upper end of the reactor 1, a ring member 10 having a groove on the inner peripheral surface is attached, and the outer peripheral portion of the annular microwave window 4 is fitted into the groove of the ring member 10 to form an annular microwave window. 4 is supported by the ring member 10. The annular microwave window 4 is made of a dielectric material such as quartz glass or alumina, which has heat resistance and microwave permeability and low dielectric loss, and is formed into an annular plate shape.

On the upper surface of the ring member 10, a cylindrical block member 25 having an outer diameter substantially the same as the outer diameter of the ring member 10 and an inner diameter substantially the same as the inner diameter of the above-described annular microwave window 4 is provided. The member 10 is screwed. The block member 25 is formed of a metal such as aluminum. An annular waveguide type antenna section in which a rectangular groove is formed in a cross section in a portion facing the annular microwave window 4 of the block member 25.
11a is formed, and on the peripheral surface of the block member 25, an introduction portion 11b formed with a rectangular hole communicating with the annular waveguide type antenna portion 11a is formed.

An annular plate member 16 made of aluminum is fitted to the bottom of the annular waveguide type antenna portion 11a, and a plurality of slits 15, 15,. Is established at a predetermined distance. A dielectric 14 such as a fluororesin such as Teflon (registered trademark), a polyethylene resin, or a polystyrene resin (preferably Teflon) is fitted inside the introduction portion 11b and the annular waveguide antenna portion 11a. That is, in the present embodiment, the annular waveguide antenna is constituted by including the annular waveguide antenna portion 11a and the plate member 16 in which the plurality of slits 15, 15,.

The peripheral surface of the block member 25,
A waveguide 31 extending from the microwave oscillator 30 is connected to the periphery of the opening of b, and the microwave oscillated by the microwave oscillator 30 passes through the waveguide 31 to the introduction portion 11b of the antenna 11.
Is incident on. This incident wave is introduced from the introduction section 11b to the annular waveguide antenna section 11a. The microwaves introduced into the annular waveguide antenna section 11a are converted into traveling waves propagating through the annular waveguide antenna section 11a in opposite directions to each other in the dielectric 14 in the annular waveguide antenna section 11a. And propagate
Both traveling waves are superimposed to form an annular waveguide antenna 11a.
, A standing wave is generated. Due to this standing wave, a wall current showing a maximum value flows at a predetermined interval through the inner surface of the annular waveguide antenna section 11a.

At this time, the mode of the microwave propagating in the annular waveguide type antenna portion 11a in which Teflon (registered trademark) having a relative permittivity εr of 2.1 is inserted is defined as a rectangular shape which is a basic propagation mode. In order to make the TE10, when the microwave frequency is 2.45 GHz, the annular waveguide antenna unit 11 is used.
The dimensions of a are 27 mm high and 66.2 mm wide. The microwave in this mode propagates through the dielectric 14 in the annular waveguide antenna 11a with almost no energy loss.

The outer diameter is 380 mm and the inner diameter is 180 m
When the Teflon (registered trademark) is fitted into the annular waveguide antenna section 11a using the annular microwave window 4 having a thickness of 20 mm and a thickness of 20 mm, the annular waveguide is inserted from the center of the annular waveguide antenna section 11a. The dimension up to the center in the width direction of the
Make 141 mm. In this case, the annular waveguide antenna section
The circumferential length of a circle connecting the widthwise center of 11a (approximately 886
mm) is substantially an integral multiple of the wavelength (approximately 110 mm) of the microwave propagating in the annular waveguide antenna section 11a.
Therefore, the microwave resonates in the annular waveguide type antenna portion 11a, and the above-described standing wave becomes a high voltage / low current at the antinode position, and becomes a low voltage / high current at the node position.
The Q value of 11 improves.

Incidentally, the annular waveguide type antenna portion 11a may be hollow without inserting the dielectric material 14. However, when the dielectric 14 is inserted into the annular waveguide antenna 11a, the wavelength of the microwave incident on the annular waveguide antenna 11a is increased by 1 / √ (εr) by the dielectric 14. Only shorter. Therefore, when the annular waveguide type antenna unit 11a having the same diameter is used, the annular waveguide type antenna unit when the dielectric 14 is mounted is more than when the dielectric 14 is not mounted. There are many locations where the current flowing through the wall of 11a is maximized, so that many slits 15, 15, ... can be opened. Therefore, the microwave can be more uniformly introduced into the processing chamber 2.

FIG. 3 shows the slit 1 shown in FIG. 1 and FIG.
It is explanatory drawing explaining 5, 15, .... As shown in FIG. 3, the slits 15, 15,... Are formed in a portion of the metal plate member 16 facing the annular waveguide type antenna portion 11a in the diameter direction of the annular waveguide type antenna portion 11a. That is, it is formed in a rectangular shape so as to be orthogonal to the traveling direction of the microwave propagating in the annular waveguide type antenna portion 11a. Annular waveguide antenna
If 11a has the dimensions described above, each slit 15, 15, ...
Has a length of 50 mm, a width of 20 mm, and a distance between adjacent slits of about 55 mm. That is, two slits are provided at a position 27.5 mm from an intersection P ₁ described later, and slits are provided at an interval of 55 mm therefrom.

That is, each of the slits 15, 15,.
An intersection point P ₁ which is a side of the two points where an extension line L extending the center line of the center line 11b intersects the above-mentioned circle C and which is separated from the introduction portion 13.
To both of them following the circle C, respectively (2m-1)
-Two slits 15, 15 are opened at a position separated by λg / 4 (m is an integer, λg is the wavelength of the microwave propagating in the annular waveguide antenna), and a circle C is formed from both slits 15, 15. ., A plurality of other slits 15, 15,... Are opened in both of them at a distance of n · λg / 2 (n is an integer). That is, the slits 15, 15, ... are provided at positions where the nodes of the standing wave described above are formed. Thereby, microwaves can be efficiently radiated from each of the slits 15, 15,....

In this embodiment, the slits 15, 1
5, ... are opened so as to be orthogonal to the traveling direction of the microwave propagating in the annular waveguide type antenna portion 11a.
The present invention is not limited to this, and a slit may be opened so as to obliquely intersect the traveling direction of the microwave, or may be opened in the traveling direction of the microwave. Due to the plasma generated in the reactor 1, the wavelength of the microwave propagating in the antenna 11 changes, and the annular waveguide antenna 11
The position where the maximum value of the current flowing through the peripheral wall of a may change, but in the slit opened in the direction of microwave propagation or the slit opened in the direction of microwave propagation, the current The change in the position showing the maximum value can be captured in the area of the slit.

As described above, each of the slits 15, 15,.
Since the plate member 16 is provided substantially radially, the microwave is uniformly introduced into the entire region in the reactor 1. On the other hand, as shown in FIG. 1, the antenna 11 is provided on the block member 25 having the same diameter as the diameter of the reactor 1 without protruding from the periphery of the block member 25. Even if it is large, the size of the plasma processing apparatus is as small as possible, so that it can be installed in a small space.

The above-mentioned block member 25 is provided with a heating block 26 formed by molding aluminum into a columnar shape so that the lower surface of the heating block 26 is slightly higher than the lower surface of the annular microwave window 4. The heating block 26 has a heater 28 embedded therein as a heating source.

A cylindrical concave portion is provided at the center of the lower surface of the heating block 26. The concave portion is closed by a counter electrode 18 formed by molding a conductor or semiconductor material into a disk, and a gas diffusion chamber 20 is provided. It is. The counter electrode 18 is detachably screwed to the heating block 26, and the counter electrode 18 is electrically grounded. When the annular waveguide antenna section 11a has the dimensions described above, the diameter of the counter electrode 18 is approximately 150 mm. The thickness of the counter electrode 18 is approximately 10 mm. On the other hand, materials used for the counter electrode 18 include Si, SiC, and Si.
A silicon-based material such as Si doped with an impurity such as N or P or B is preferable.

The screw for fixing the counter electrode 18 and the lower surface of the above-mentioned annular microwave window 4 are protected by an annular protective plate (not shown) made of quartz. Also, reactor 1,
At the part where the ring member 10, the annular microwave window 4, the block member 25 and the heating block 26 are joined to each other, heat-resistant O-rings 17, 17,... Each is interposed.

The inside of the gas diffusion chamber 20 is a partition wall.
The upper and lower chambers are divided by 19, and a plurality of through holes are opened in the partition wall 19 and the counter electrode 18 at different positions in the vertical direction. The gas diffusion chamber 20 is connected to a gas introduction pipe 5 that passes through the heating block 26. The gas supplied from the gas introduction pipe 5 to the gas diffusion chamber 20 diffuses into the upper chamber of the gas diffusion chamber 20 and is supplied to the lower chamber of the gas diffusion chamber 20 through a through hole formed in the partition wall 19, where the gas is uniformly diffused. After being converted, it is introduced into the processing chamber 2 through a through hole formed in the counter electrode 18.

FIG. 4 is a bottom view of the counter electrode 18 shown in FIG. As shown in FIG. 4, the bottom surface of the counter electrode 18, ie, FIG.
The surface opposite to the processing chamber 2 shown in FIG.
N) and the like, a pattern in which a dielectric material is evenly provided around the center axis of the counter electrode 18, in the case shown in FIG. 4, a plurality of fan-shaped regions each having the same area are formed around the center axis of the counter electrode 18. A plurality of guiding portions 18a, 18a,... Are formed by depositing them in an evenly distributed pattern, and a plurality of fan-shaped electrode portions are provided between adjacent guiding portions 18a, 18a,.
18b, 18b,... Are formed. The counter electrode 18 is provided with a plurality of through holes 22, 22 penetrating through the guide portions 18a, 18a,... And the electrode portions 18b, 18b,.

FIGS. 5 and 6 show the guide portions 18a, 18a described above.
,... Are explanatory diagrams for explaining other patterns. In the pattern shown in FIG. 5, a plurality of annular guiding portions having different diameters are provided.
Are provided concentrically with the center axis of the counter electrode 18. As a result, a circular electrode portion 18a is formed at the center of the counter electrode 18, and the adjacent guide portions 18a, 18a,
The annular electrode portions 18b, 18b,... Are formed between. Further, in the pattern shown in FIG.
, And the electrode portions 18b, 18b, ... are arranged in a checkered pattern. In FIGS. 5 and 6, a through hole for supplying gas is omitted.

In the pattern shown in FIG. 5, the circular electrode portion 18b is disposed at the center of the counter electrode 18, but the present invention is not limited to this, and the circular guide portion 18a is disposed at the center of the counter electrode 18.
Needless to say, it may be arranged. Further, in the pattern shown in FIG. 6, square guiding portions 18a, 18a,... Are provided, but the present invention is not limited to this. Needless to say, the portion may be an electrode portion. In this case, the position of the guide portion and the position of the electrode portion may be switched, a plurality of circular electrode portions may be provided on the counter electrode, and another portion of the counter electrode may be used as the guide portion.

In such a counter electrode 18, as will be described later, the microwave guided around the counter electrode 18 is guided directly below the counter electrode 18 by the guide portions 18a, 18a,. The portions 18b, 18b, ... function as ground electrodes.

At the center of the bottom wall of the processing chamber 2, a mounting table 3 for mounting the workpiece W is provided so as to be able to move up and down. A high frequency power source 7 is connected to the mounting table 3 via a matching box 6. I have. Further, an exhaust port 8 is provided in a peripheral wall of the processing chamber 2, and the inside air of the processing chamber 2 is exhausted from the exhaust port 8. The high frequency applied to the mounting table 3 is mainly for controlling ions in the plasma, and the frequency is 200 kHz to 2 MHz. However, a voltage up to several tens of MHz may be applied in some cases.

In order to perform an etching process on the surface of the workpiece W using such a plasma processing apparatus, the heating block 26 and the counter electrode 18 are heated to a required temperature by the heater 28 and exhausted from the exhaust port 8. To reduce the pressure inside the processing chamber 2 to a desired pressure.
The reaction gas is supplied to the inside, and the reaction gas diffused and made uniform inside is introduced into the processing chamber 2 from the counter electrode 18.

Next, a microwave is oscillated from the microwave oscillator 30 and is introduced into the antenna 11 through the waveguide 31 to form a standing wave in the annular waveguide type antenna section 11a. Due to this standing wave, the slits 15, 1
The electric field radiated from 5,... Passes through the annular microwave window 4 and is introduced into the processing chamber 2, and plasma is generated in the processing chamber 2.

The electric field introduced into the processing chamber 2 is a counter electrode.
Are propagated through the guiding portions 18a, 18a,... Provided on the bottom surface of the 18, and are also guided directly below the counter electrode 18, whereby an electric field is formed in substantially the entire region below the annular microwave window 4 and the counter electrode 18. Therefore, plasma having a substantially uniform density is generated in a plane parallel to the mounting table 3.

A high frequency is applied to the mounting table 3 from the high frequency power source 7 via the matching box 6 simultaneously with the oscillation by the microwave oscillator 30. Due to the electric field formed between the mounting table 3 and the counter electrode 18, the ions in the generated plasma are guided onto the workpiece W, and the surface of the workpiece W is etched.

As described above, the ions in the plasma are introduced onto the workpiece W by the electric field formed between the electrode portions 18b, 18b,... Of the opposing electrodes 18 arranged opposite to the mounting table 3 and the mounting table 3. In addition, the ions in the plasma are prevented from colliding with and damaging the inner peripheral surface of the reactor 1, and the life of the reactor 1 is extended. Further, since the electric field is formed in a direction orthogonal to the surface of the processing object W, a stable bias potential is generated on the surface of the mounting table 3, and the directivity of ions incident on the processing object W is high, Process characteristics are improved.

Further, the microwave transmitted through the microwave window and introduced into the container is guided immediately below the counter electrode 18 by a plurality of guide portions 18a, 18a,. An electric field is formed in substantially the entire region inside the processing chamber 2 facing the annular microwave window 4 and the counter electrode 18, and plasma having a substantially uniform density is generated in a plane parallel to the mounting table 3. Therefore, the process characteristics are further improved.

On the other hand, since the opposite electrode 18 is detachably screwed to the heating block 26, if the opposite electrode 18 is damaged, it can be easily replaced. Further, when the counter electrode 18 is heated to a required temperature, the process characteristics are further improved.

By the way, from the bottom of the counter electrode 18, the processing chamber 2
Since the reaction gas is introduced into the reaction chamber, the reaction gas has a flat cross-sectional area having a diameter substantially equal to the diameter of the processing object W on the processing object W in the processing chamber 2 and is substantially uniform. The workpiece W is supplied as a stream, and the surface of the workpiece W is processed substantially uniformly. Further, the reaction gas supplied into the processing chamber 2 stays in the plasma for a long time, so that the utilization efficiency of the reaction gas is improved.

Further, when the counter electrode 18 is formed of a silicon-based material, for example, when etching a silicon oxide film using a fluorocarbon-based reaction gas (C _x F _y gas), fluorine molecules are removed from the electrode portion of the counter electrode 18. 18b, 18b
,... React with each other and vaporize as SiF ₄ , so that fluorine molecules can be selectively removed. As a result, the etching rate of the silicon oxide film with respect to the etching rate of the resist is improved, and etching with a high selectivity can be performed. In addition, since the reaction product (SiF ₄ ) is a volatile substance, contamination of the article to be processed W by the reaction product is avoided.

In the present embodiment, the counter electrode 18 is electrically grounded. However, the present invention is not limited to this, and a configuration in which a high frequency is applied to the counter electrode 18 may be employed. For example,
A high frequency of 200 kHz to 2 MHz is applied to the mounting table 3,
When a high frequency of 13.56 MHz or 27 MHz is applied to the counter electrode 18, by adding a mechanism for electrically grounding each electrode through a filter that passes a frequency range of the high frequency applied to the other electrode, Although it is configured to apply a high frequency, it can function as a ground electrode for other electrodes.

(Embodiment 2) FIG. 7 is a schematic partial inner view showing Embodiment 2 in which the shape of the antenna is changed. In the figure, portions corresponding to the portions shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. One end of the antenna 12 is connected to a waveguide 31 (both shown in FIG. 1) connected to the microwave oscillator 30, and the other end of the antenna 12 is closed. One end of the antenna 12 is linear, and the other end is a curved portion 12a formed to have an appropriate curvature, such as a C shape (arc shape) or a single spiral shape (C shape in FIG. 7). It has been done. A plate member is fitted to the bottom of the antenna 12, and a plurality of slits are formed in a portion of the plate member corresponding to the curved portion 12a.
15, 15, ... are established.

The slits 15, 15,...
a is formed at a position opposite to the center axis of the bent portion 12a so as to be orthogonal to the central axis of the bent portion 12a. Stipulated in That is, each of the slits 15, 15,... Is opened at a position indicating the maximum value of the current flowing through the bottom surface in the antenna, and each of the slits 15, 15,. An electric field is radiated from..., And the electric field passes through the annular microwave window 4 and is introduced into the reactor 1 (both shown in FIG. 1).

A circular counter electrode 18 is fitted in the center of the bent portion 12a. On the bottom surface of the counter electrode 18, a plurality of guiding portions each formed by depositing a dielectric in a pattern as described above are provided, and a plurality of electrode portions formed between each guiding portion and adjacent guiding portions are provided. A plurality of through holes (all not shown) are formed.

In such a plasma processing apparatus,
As before, the antenna 12 is provided on the block member 25 having the same diameter as the diameter of the reactor without protruding from the peripheral edge of the block member 25. Therefore, even if the diameter of the reactor is large, the size of the plasma processing apparatus can be reduced. Is as small as possible and can therefore be installed in small spaces.

In order to guide ions in the plasma to an object to be processed on the mounting table by an electric field formed between the mounting section and the electrode portions 18b, 18b,... Of the counter electrode 18 opposed to the mounting table. The ion in the plasma is prevented from colliding with and damaging the inner peripheral surface of the reactor, and the life of the reactor is extended. In addition, since the electric field is formed in a direction orthogonal to the surface of the processing object, a stable bias potential is generated on the surface of the mounting table, the directivity of ions incident on the processing object is high, and the process characteristics are low. improves.

Further, the microwaves transmitted through the microwave window and introduced into the container are guided immediately below the counter electrode 18 by a plurality of guide portions provided on the counter electrode 18, so that the microwaves are generated inside the processing chamber. The annular microwave window and the counter electrode 18
An electric field is formed in substantially the entire region facing the substrate, and plasma having a substantially uniform density is generated in a plane parallel to the mounting table.
Process characteristics are further improved.

[0061]

As described above in detail, in the plasma processing apparatus according to the present invention, the horizontal dimension of the plasma processing apparatus can be made as small as possible. In addition, since the counter electrode acts as a ground electrode with respect to the mounting table to which a high frequency is applied, ions in the plasma are prevented from colliding with the inner peripheral surface of the container and causing damage, and the life of the container is long.
In addition, since ions in the plasma are guided by an electric field formed between the mounting table and the counter electrode, the ions are substantially vertically incident on the object to be processed, and process characteristics such as anisotropy are improved.

Further, the microwave introduced through the microwave window and introduced into the container is guided immediately below the counter electrode by a guide portion provided on one or a plurality of portions of the surface of the counter electrode facing the mounting table. Therefore, an electric field is formed in substantially the entire region facing the annular microwave window and the counter electrode inside the container, and plasma having a substantially uniform density is generated in a plane parallel to the mounting table. Thereby, the process characteristics are further improved.

In the plasma processing apparatus according to the third aspect of the invention, the microwave can be guided with a substantially uniform intensity directly below the opposing electrode, and a plasma having a substantially uniform density can be generated immediately below the opposing electrode. it can.

In the plasma processing apparatus according to the fourth aspect of the present invention, since the counter electrode is formed of a silicon-based material, for example, in etching a silicon oxide film, the etching rate of the silicon oxide film is improved with respect to the etching rate of the resist. However, the present invention has excellent effects, such as etching with a high selectivity.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a structure of a plasma processing apparatus according to the present invention.

FIG. 2 is a plan view of the plasma processing apparatus shown in FIG.

FIG. 3 is an explanatory diagram illustrating a slit shown in FIGS. 1 and 2.

FIG. 4 is a bottom view of the counter electrode shown in FIG. 1;

FIG. 5 is an explanatory diagram for explaining another pattern of the guiding unit.

FIG. 6 is an explanatory diagram for explaining another pattern of the guiding unit.

FIG. 7 is a schematic partial inner view showing the second embodiment.

FIG. 8 is a side sectional view showing a plasma processing apparatus of the same type as a conventional apparatus.

FIG. 9 is a plan view of the plasma processing apparatus shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor 2 Processing chamber 3 Mounting table 4 Annular microwave window 10 Ring member 11 Antenna 11a Annular waveguide type antenna part 11b Introduction part 15 Slit 16 Plate member 18 Counter electrode 18a Induction part 18b Electrode W

Claims (7)

[Claims] A container in which a mounting table on which an object to be processed is mounted is provided; a counter electrode facing the mounting table;
An annular microwave window externally fitted to the counter electrode; and an annular waveguide antenna disposed to face the microwave window and emitting microwaves to the microwave window. An apparatus that transmits the microwave window from an antenna to introduce microwaves into a container to generate plasma and apply high frequency to the mounting table, and that the processing target is processed by the generated plasma. A plasma processing apparatus, wherein a guide portion for guiding microwaves introduced into a container is provided on a surface of a counter electrode facing a mounting table. 2. The plasma processing apparatus according to claim 1, wherein the guiding section is formed of a dielectric. 3. The plasma processing apparatus according to claim 1, wherein the guide portion is disposed substantially evenly around a center axis of the counter electrode. 4. The plasma processing apparatus according to claim 1, wherein said counter electrode is formed of a silicon-based material. 5. The plasma processing apparatus according to claim 1, further comprising an endless annular waveguide antenna. 6. The plasma processing apparatus according to claim 1, further comprising a terminated annular waveguide antenna. 7. The plasma processing apparatus according to claim 6, wherein the waveguide type antenna is formed in a C shape or a spiral shape.