JP2003203799A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus capable of performing plasma processing with high efficiency and reproducibility by securely absorbing fluctuation of a standing wave forming condition of a micro wave in a micro wave supply system. <P>SOLUTION: A reactance element 150 is provided in the middle of a wave guide path for guiding the micro wave of the micro wave supply system for introducing the micro wave through a transmitting window in a vacuum chamber. Thereby, the micro wave resonates between the reactance element and a terminal of the micro wave supply system, so that a stable standing wave can be formed. Furthermore, a variable short circuit device provided on the terminal of the micro wave supply system provides the plasma processing apparatus capable of forming the standing wave of the micro wave stably and forming stable plasma even when a process condition or the like is fluctuated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus, for example, in a microwave-excited plasma processing apparatus using an applicator or the like, by controlling the propagation of microwaves, stable plasma can be reproduced with high reproducibility. The present invention relates to a plasma processing apparatus that can generate plasma.

[0002]

2. Description of the Related Art Plasma processing such as etching, ashing, thin film deposition or surface modification using plasma is widely used in the field of manufacturing various devices and parts including semiconductor devices and liquid crystal display devices.

As an example of a plasma processing apparatus used for these processes, a microwave excitation type plasma processing apparatus using an "applicator" will be described below as an example.

FIG. 8 is a schematic view showing the structure of a main part of a chamber of a microwave excited plasma processing apparatus using an applicator. That is, FIG. 4A is a cross-sectional view illustrating the overall structure, and FIG. 1B is a plan view of the applicator viewed from the direction of arrow A.

The plasma processing apparatus shown in FIG. 8 has a vacuum chamber 102 and a mounting table 104 provided therein. The interior of the chamber 102 is evacuated by a vacuum pump (not shown) through the exhaust port 106, as indicated by an arrow E in FIG. An object S to be processed, which is subjected to plasma processing such as etching, is installed on the mounting table 104. An applicator 110 is provided above the mounting table 104 via a transmission window 108, and the applicator 110 includes the waveguide 11
Connected to 2.

A slot 110S as a slit-shaped opening is provided near the center of the applicator 110. The microwave is guided in the direction of the arrow M in the waveguide 112, and is introduced into the internal space of the chamber 102 from the slot 110S through the transmission window 108.

On the other hand, the inside of the chamber 102 is evacuated and a predetermined gas is introduced to maintain an appropriate pressure state, and plasma P is formed by the microwave introduced through the transmission window 108. Due to the action of the plasma P thus formed, the object S to be processed is subjected to a predetermined plasma processing such as etching or surface modification.

FIG. 9 is a schematic diagram showing a microwave supply system in such a plasma processing apparatus. That is,
The microwave generated by the oscillator 120 is guided by the waveguide 112 via the isolator (separator) 130 and the matcher (matching device) 140. Isolator 130
Serves to prevent the influence of reflected microwaves returning to the oscillator 120. Also, matcher 14
0 plays a role of adjusting impedance matching between the oscillator 120 and the load side.

In the plasma processing apparatus having the microwave supply system as described above, a microwave resonator is formed from the matcher 140 to the end of the applicator 110. Therefore, the mode of the plasma P generated by the slot radiation type applicator 110 is determined by the influence of the standing wave of the microwave formed in the microwave supply system.

The standing wave is generated by the matcher 140.
To the end of the slot radiating applicator 110, and the resonance circuit including the absorption rate of microwaves absorbed by the plasma in the slot 110S.

For example, in the case of a device using microwaves having a wavelength of 2.45 GHz (gigahertz), the matcher 14
Pipe length from 0 to the end of applicator 110 is 11
When it is set to 20 mm, the standing wave forming condition of the microwave is satisfied inside the waveguide 112, and the standing wave “hara” is generated.
The calculation is that 14 are formed.

[0012]

However, in the case of an actual plasma processing apparatus, the standing wave forming condition of such a microphone wave may "shift" due to the following three reasons.

First, the first reason is "deviation" in the total length of the resonator. That is, there are cases where the total length of the resonator is "shifted" from a predetermined value due to "machine differences" from the design dimensions of the individual components that make up the microwave supply system. In addition, the total length of the resonator may be “shifted” due to temperature rise, aging, or the like. Due to such "deviation" of the total cavity length, the microwave standing wave forming condition also "devits". In an extreme case, the microwave standing wave "hara" that is formed in the microwave The number of may change.

The second reason is a change in the initial operation of the matcher 140. That is, the matcher 140 has a role of adjusting the impedance matching between the oscillator 120 and the load side, but its response may fluctuate due to various factors. Then, the balance of the reflected waves from the load side fluctuates, so that the standing wave forming condition may fluctuate.

The third reason is a change in the absorption rate of microwaves on the load side. That is, the microwave introduced into the chamber 102 through the slot 110S is absorbed by the plasma P, but the state of the plasma P is changed according to the gas species, pressure, flow rate distribution, surface state of the inner wall, etc. in the chamber 102. May fluctuate, and as a result, the microwave absorption rate may also change. When the microwave absorptance changes in this way, the standing wave forming conditions also change.

Of the first to third reasons explained above, with respect to the second reason, that is, the variation of the initial operation of the matcher 140, the initial operation position is fixed, the operation range is limited, or the matcher is changed. It is possible to suppress the fluctuation by a method such as making the response sensitivity of (3) slower.

However, regarding the first and third reasons,
There is no effective countermeasure, and the standing wave forming condition of the microwave deviates from the design value, so that the mode of the plasma P may deviate from the design value.

If the plasma mode changes during the process treatment (hereinafter referred to as "mode jump"), the input power during that period will be lost. Therefore, there is a problem that the process performance decreases as the number of mode jumps increases. That is, there is a problem in that the efficiency is lowered and the reproducibility of the plasma treatment is deteriorated.

The present invention has been made on the basis of the recognition of such a problem, and an object of the present invention is to reproduce efficiently by reliably absorbing the fluctuation of the standing wave forming condition of the microwave in the microwave supply system. An object of the present invention is to provide a plasma processing apparatus capable of highly efficient plasma processing.

[0020]

To achieve the above object, the first plasma processing apparatus of the present invention is a vacuum chamber capable of maintaining an atmosphere depressurized to the atmosphere, and a part of the wall surface of the vacuum chamber. And a microwave supply system that guides microwaves outside the vacuum chamber and introduces the microwaves into the vacuum chamber via the transmission window. A plasma processing apparatus capable of generating plasma by the microwave introduced into the vacuum chamber, wherein a variable short circuiter is provided at the end of the microwave supply system.

According to the above structure, a standing wave of microwave can be stably formed and stable plasma can be formed even if the process conditions are changed.

Further, the second plasma processing apparatus of the present invention is such that a vacuum chamber capable of maintaining an atmosphere decompressed with respect to the atmosphere, a transmission window occupying a part of the wall surface of the vacuum chamber, and an outside of the vacuum chamber. And a microwave supply system for guiding the microwave into the vacuum chamber through the transmission window, and the microwave introduced into the vacuum chamber through the transmission window. A plasma processing apparatus capable of generating plasma by means of a reactance element provided on the way of a waveguide path through which microwaves are guided in the microwave supply system, whereby the reactance element and the microwave supply system It is characterized in that the microwave resonates with the terminal to form a standing wave.

According to the above structure, it is possible to suppress the "difference" in the resonance condition due to the "machine difference" of each part of the plasma supply system, the temperature change, the secular change, etc., and to form a stable microwave standing wave. it can.

In this plasma processing apparatus, the distance from the reactance element to the terminal end is approximately equal to a real multiple of λg / 2, where λg is the guide wavelength of the guided microwave. Therefore, the standing wave of the microwave can be reliably formed.

Further, the microwave supply system has a slot for emitting the guided microwave to the transmission window, and the reactance element sandwiches the slot between the reactance element and the end. In addition, if it is provided in the vicinity of the end of the slot, the resonator length can be minimized to minimize fluctuation due to temperature and improve stability.

Further, if a variable short circuiter is provided at the end of the microwave supply system, fine adjustment can be performed and stable microwave standing can be achieved even if the process conditions change. A wave can be formed and a stable plasma can be formed.

Further, if the reactance element is movable along the direction of wave guide of the microwave, it is possible to further flexibly adjust a wide range of microwave standing wave forming conditions.

The apparatus further comprises monitor means for monitoring the state of the plasma generated in the vacuum chamber, and control means for adjusting the variable short-circuiter based on a signal from the monitor means. By doing so, it becomes possible to make dynamic and quick adjustments according to changes in process conditions.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram showing a microwave supply system of a plasma processing apparatus according to an embodiment of the present invention.
That is, the microwave generated by the oscillator 120 is transmitted to the isolator (separator) 130 and the matcher (matcher) 14
It is guided by the waveguide 112 through 0. The isolator 130 serves to prevent the reflected microwaves from returning to the oscillator 120 and being influenced thereby. Further, the matcher 140 plays a role of adjusting impedance matching between the oscillator 120 and the load side.

The microwave guided through the waveguide 112 is
Propagated to the applicator 110. Applicator 110
Near the center of the slot 1 as a slit-shaped opening
10S is provided. The microwave M is applied to the waveguide 11
2 is guided in the direction of arrow A in FIG.

The inside of the chamber 102 has, for example, a structure as shown in FIG. 8, is evacuated and a predetermined gas is introduced to maintain an appropriate pressure state, and is introduced through a transmission window. Plasma P is formed by the microwave. Due to the action of the plasma P thus formed, the object to be processed is subjected to predetermined plasma processing such as etching and surface modification.

The space for forming the plasma P and the space for placing the object to be processed may be separated. That is, a plasma forming chamber and a plasma processing chamber are provided,
A microwave may be introduced into the plasma forming chamber to form the plasma P, and the plasma P may be introduced into the plasma processing chamber to perform plasma processing on the object to be processed.

Now, in the present invention, as shown in FIG. 1, a reactance element (resonance window) is provided in the microwave supply system.
150 is provided. The reactance element 150 has a role of adjusting the phase of the guided microwave, and specifically, for example, an element having a function similar to that of a directional coupler can be used. That is, it is possible to use, as the reactance element 150, an element in which the transmittance of the microwave guided from the matcher 140 and the transmittance of the microwave reflected from the load side are different. With this configuration, the microwave guided from the oscillator 120 can be supplied to the load side and the microwave returning from the load side can be reflected.

2 and 3 are schematic views showing a concrete example of the reactance element. That is, FIG. 7A is a view seen from the axial direction of the waveguide, and FIG. 7B is a view seen from a direction perpendicular to the waveguide axis.

The reactance element of these specific examples has a plate-like form provided inside the waveguide 112, and has an opening OP smaller than the inner diameter of the waveguide shown by the broken line in the figure. Further, a threaded hole H for mounting is appropriately provided on the outer peripheral flange portion of the waveguide.

As described above, the plate-shaped member having the opening OP smaller than the inner diameter of the waveguide 112 functions as the reactance element in the present invention. In the case of the specific examples shown in FIGS. 2 and 3, the plate thickness of the reactance element is, for example, about 1 millimeter, and the material thereof can be formed of aluminum, brass, or the like similar to the waveguide 112.

By providing such reactance element 150, a microwave resonance circuit can be formed between the end of the applicator 110 and the reactance element 150. That is, the microwave can resonate between the applicator 110 and the reactance element 150 to form a standing wave. As a result, it is possible to suppress the influence of fluctuations in the total length of the resonator due to "machine difference" in the microwave supply system, temperature rise, or secular change, and to suppress "deviation" in the standing wave formation conditions for microwaves. it can.

When the slot type applicator illustrated in FIG. 1 is used, it is desirable that the reactance element 150 be provided between the matcher 140 and the slot 110S, and as close as possible to the slot 110S. desirable. This is because the resonator length can be shortened and the fluctuation can be suppressed to the minimum.

In order to satisfy the microwave resonance condition, the reactance element 150 is changed to the applicator 110.
Is arranged so that the pipe length up to the terminal end (strictly, up to the plunger 160) is a real multiple of half (1/2) of the in-tube wavelength of the microwave. By doing so, a microwave standing wave can be stably formed in the waveguide space from the reactance element 150 to the end of the applicator 110. Then, microwaves are introduced into the chamber 102 according to the distribution of the standing waves, and the plasma P can be stably formed.

Furthermore, in the present invention, as shown in FIG. 1, a plunger (variable short circuit) 160 is provided at the end of the applicator 110. Plunger 160
It is an element that adjusts the pipeline length by changing the end position and short-circuits the end. Such a plunger 16
By setting 0, the total length of the resonator can be adjusted, and it is possible to flexibly deal with fluctuations in the absorption rate of microwaves on the load side. That is, the chamber 102
In some cases, the state of the plasma P formed varies depending on process conditions such as gas species, pressure, and flow rate distribution inside the chamber, the surface state of the chamber inner wall, and the like, and as a result, the microwave absorptivity changes. is there. When the microwave absorptance changes in this way, the standing wave forming conditions also change.

On the other hand, by providing the plunger 160, the resonator length from the reactance element 150 can be adjusted. As a result, even if the process condition or the like fluctuates, the resonance condition corresponding thereto can be satisfied, and a stable microwave standing wave is formed between the reactance element 150 and the plunger 160 to stabilize. Plasma P can be formed.

In the case where the microwave standing wavelength can be changed in this way, a slot 110S provided in the applicator 110 in order to deal with this in a wide range.
It is desirable to form the opening width of the.

FIG. 4 is a schematic diagram showing a concrete configuration example of the plunger 160. That is, as shown in FIG. 3A, the mover 1 is brought into contact with the inner wall of the applicator 110.
A plunger 160 in which the position of 60A can be adjusted by the drive mechanism 160B can be used. However, in this case, the contact state or “gap” between the inner wall of the applicator 110 and the mover 160A may be a problem.

On the other hand, the plunger illustrated in FIGS. 4 (b) and 4 (c) has a so-called "choke-type" structure that can create a narrow gap while creating an electrically short-circuited state. Have. Each of these choke-type plungers has two waveguide portions having a tube length of λg / 4 for the in-tube wavelength λg of the microwave. The impedances of these two waveguide parts are Z1 and Z1, respectively.
It is Z2.

FIG. 4D is an equivalent circuit diagram of the choke type plunger illustrated in FIGS. 4B and 4C. Since the impedance relationship of the waveguide is Z1 << Z2, it can be easily understood from this circuit diagram that Zin˜0. That is, it is possible to more reliably short-circuit the terminal.

As described above, according to the present invention, by providing the reactance element 150 in the microwave supply system of the plasma processing apparatus, the "deviation" of the resonance condition due to "machine difference", temperature change, or secular change. Can be suppressed and a stable microwave standing wave can be formed.

Furthermore, according to the present invention, by providing the plunger 160, a microwave standing wave can be stably formed between the reactance element 150 and the plunger 160 even if the process condition or the like changes. Therefore, stable plasma P can be formed.

As a result, it is possible to realize a plasma processing apparatus which forms stable plasma and is capable of highly reproducible plasma processing.

Next, a modified example of the present invention will be described.

FIG. 5 is a schematic diagram showing a microwave supply system of a plasma processing apparatus as a first modified example of the present invention. In this figure, elements similar to those described above with reference to FIGS. 1 to 4 are marked with the same reference numerals and not described in detail.

In this modified example, the plunger is not provided, and instead, the reactance element (resonance window) 15 is used.
0 is movable by the drive mechanism 170. In this case, the reactance element 150 and the applicator 110
Microwave resonance occurs with the end of the drive mechanism. However, the fine adjustment of the resonator length due to fluctuations in process conditions causes the drive mechanism 1
This can be done by adjusting the position of the reactance element 150 by 70.

As a result, a stable plasma can be formed similar to that described above with reference to FIGS.

FIG. 6 is a schematic diagram showing a microwave supply system of a plasma processing apparatus as a second modified example of the present invention. In this figure, elements similar to those described above with reference to FIGS. 1 to 5 are marked with the same reference numerals and not described in detail.

In this modification, the plunger 160 is provided and the reactance element (resonance window) 150 is also movable by the drive mechanism 170. In this way, the microwave resonator length can be adjusted more flexibly and over a wide range, and a wide range of process conditions and device designs can be accommodated.

FIG. 7 is a schematic diagram showing a microwave supply system of a plasma processing apparatus as a third modified example of the present invention. In this figure, elements similar to those described above with reference to FIGS. 1 to 6 are marked with like reference numerals and not described in detail.

In this modification, the chamber 102 is
A process monitor 180 is provided so that the state of the plasma P can be monitored. The process monitor 180 may measure, for example, the density of the plasma P at a predetermined position inside the chamber 102. Alternatively,
The process monitor 180 may measure the density distribution of the plasma P continuously or discretely. As the process monitor 180, for example, one that measures the emission intensity from the plasma P or its spectrum can be used.

The plasma measurement result by the process monitor 180 is supplied to the controller 190, and the controller 190 adjusts the plunger 160 based on the measurement result. That is, the plunger 160 can be automatically adjusted according to the state of the plasma P so as to optimize the resonance condition of the microwave.

By doing so, even if the state of the plasma P changes due to changes in the process conditions and various other factors, it is possible to quickly adjust the standing wave forming conditions of the microwave and cope with the situation. As a result, it is possible to realize a plasma processing apparatus that can always perform stable and highly reproducible plasma processing.

In FIG. 7, the controller 19
However, the present invention is not limited to this, and for example, the drive mechanism 170 in the configuration shown in FIG. 5 may be automatically adjusted by the controller 190, and FIG. One or both of the plunger 160 and the drive mechanism 170 in the configuration shown in FIG. 2 may be automatically adjusted by the controller 190.

The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

For example, in the present invention, the shape of the slot for radiating the microwave is not limited to the rectangular shape as shown in the drawing, and for example, as disclosed in Japanese Patent No. 2857090, the microwave It may have an opening shape such that the front side is wide with respect to the waveguide direction and the side close to the terminal reflection surface of the waveguide is narrow.

The length of the slot is also nλ / 2 to nλ / 2 + λ with respect to the wavelength λ of the microwave.
It can be within the range of / 8.

Furthermore, the center in the lengthwise direction of such a slot can be located at a distance of the wavelength λ of the microwave from the terminal reflecting surface of the waveguide.

Further, the present invention is not limited to the plasma processing apparatus which introduces the microwave into the chamber through the slot, but the plasma which introduces the microwave into the chamber through the opening of various shapes or other introducing means. The same effects can be obtained by applying the same to a processing apparatus, and these various microwave-excited plasma processing apparatuses are also included in the scope of the present invention.

[0066]

As described in detail above, according to the present invention,
By providing a reactance element in the microwave supply system of the plasma processing device, it is possible to suppress the "difference" in the resonance condition due to "machine difference", temperature change, or secular change, and to form a stable microwave standing wave. You can

Further, according to the present invention, by providing the plunger, even if the process condition or the like changes,
A standing wave of microwaves can be stably formed between the reactance element and the plunger, and stable plasma can be formed.

As a result, it is possible to realize a plasma processing apparatus capable of forming stable plasma and performing plasma processing with high reproducibility, which is a great industrial advantage.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a microwave supply system of a plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a specific example of a reactance element.

FIG. 3 is a schematic diagram showing a specific example of a reactance element.

FIG. 4 is a schematic diagram showing a specific configuration example of a plunger 160.

FIG. 5 is a schematic diagram showing a microwave supply system of a plasma processing apparatus as a first modified example of the present invention.

FIG. 6 is a schematic diagram showing a microwave supply system of a plasma processing apparatus as a second modified example of the present invention.

FIG. 7 is a schematic diagram showing a microwave supply system of a plasma processing apparatus as a third modified example of the present invention.

8A and 8B are schematic views showing a structure of a main part of a chamber of a microwave excitation type plasma processing apparatus using an applicator, FIG. 8A being a cross-sectional view illustrating the entire structure, and FIG. 3 is a plan view of the applicator viewed from the direction of arrow A. FIG.

FIG. 9 is a schematic diagram showing a microwave supply system in a conventional plasma processing apparatus.

[Explanation of symbols]

102 vacuum chamber 104 mounting table 106 exhaust port 108 transparent window 110 Applicator 110S slot 112 Waveguide 120 oscillator 130 Isolator 140 matcher 150 reactance element (resonance window) 160 Plunger (variable short circuit) 160A mover 160B drive mechanism 170 Drive mechanism 180 Process Monitor 190 controller M microwave P plasma S Processing object

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[Procedure amendment]

[Submission date] January 9, 2002 (2002.1.9)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

[Figure 7]

[Figure 8]

[Figure 9]

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/3065 H01L 21/302 BF term (reference) 4G075 AA24 AA30 AA61 AA62 BC04 BC06 BC10 BD14 CA26 CA47 EB44 4K030 FA01 KA30 KA45 5F004 BA20 BB14 BD01 BD04 CA03 CB02

Claims (7)

[Claims] 1. A vacuum chamber capable of maintaining an atmosphere decompressed with respect to the atmosphere, a transmission window occupying a part of a wall surface of the vacuum chamber, and a microwave guided outside the vacuum chamber,
A microwave supply system for introducing the microwave into the vacuum chamber through the transmission window; and plasma capable of generating plasma by the microwave introduced into the vacuum chamber through the transmission window. A plasma processing apparatus, comprising a variable short circuiter provided at a terminal of the microwave supply system. 2. A vacuum chamber capable of maintaining an atmosphere decompressed with respect to the atmosphere, a transmission window occupying a part of a wall surface of the vacuum chamber, and a microwave guided outside the vacuum chamber,
A microwave supply system for introducing the microwave into the vacuum chamber through the transmission window; and plasma capable of generating plasma by the microwave introduced into the vacuum chamber through the transmission window. In the processing device, by providing a reactance element on the way of a waveguide path along which the microwave is guided in the microwave supply system, the microwave is provided between the reactance element and the end of the microwave supply system. The plasma processing apparatus is characterized in that a standing wave is formed by resonance. 3. The distance from the reactance element to the terminal end is substantially equal to a real multiple of λg / 2, where λg is a guide wavelength of a guided microwave. Plasma processing equipment. 4. The microwave supply system has a slot for emitting the guided microwave to the transmission window, and the reactance element sandwiches the slot between the reactance element and the end. The plasma processing apparatus according to claim 2 or 3, wherein the plasma processing apparatus is provided close to an end of the slot. 5. The plasma processing apparatus according to claim 2, wherein a variable short circuiter is provided at the end of the microwave supply system. 6. The plasma processing apparatus according to claim 2, wherein the reactance element is movable along a waveguide direction of the microwave. 7. A monitor means for monitoring the state of plasma generated in the vacuum chamber, and a control means for adjusting the variable shunt circuit based on a signal from the monitor means. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is a plasma processing apparatus.