JPH10189295A - Plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing device in which a plasma process can be uniformly performed to a subject body for a large surface, and in which microwave power usage efficiency can be improved compared to conventional examples. SOLUTION: A device is provided with a microwave power source 1, a rectangular waveguide 4A to introduce microwaves outputted from the microwave power source 1, and a plasma processing chamber 7 having a thin and long window part 7c in a side wall for a subject body 13 to be disposed to face the window part 7c, microwaves introduced to the rectangular waveguide 4A to be radiated through the window part 7c to generate plasma, so a specified process is performed to the subject body 13. A microwave radiator 6 having a thin and long aperture part is disposed to put the end aperture part to face the window part 7c, and a matching transformer 5 is provided between the rectangular waveguide 4A and a microwave radiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a plasma processing apparatus for performing processing such as thin film formation, surface modification and etching on a large-area workpiece uniformly and at high speed.

[0002]

2. Description of the Related Art In recent years, a plasma apparatus using microwaves has been used for etching, ashing, CVD and the like in a semiconductor and LCD manufacturing process. FIG. 12 is an overall configuration diagram of a conventional plasma processing apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 5-335095, and FIG. 13 is a cross-sectional view taken along line II of FIG. This device comprises a microwave power supply 1,
A rectangular waveguide 4A on which an isolator 2, a directional coupler 3, and an impedance matching device 4 are mounted, a rectangular plasma processing chamber 7 for performing plasma processing, and a rectangular waveguide 8 for plasma chamber coupling with the plasma processing chamber mounted on a side surface. , A termination device 9.

As shown in FIG. 13, a plasma processing chamber 7 has an elongated rectangular window 7b extending along the tube axis of the rectangular waveguide 8 on a side wall 7a on the side of the rectangular waveguide 8 for coupling. The window portion 7b is vacuum-sealed by the microwave transmitting window 11. The window portion 7b is arranged to face the E surface 8a of the rectangular waveguide 8 via the microwave transmitting window. Here, the E plane is a side surface parallel to the direction of the electric field vector in the rectangular waveguide. Further, the plasma processing chamber 7 is provided with an exhaust port 7c, which is connected to a vacuum pump (not shown). Is attached. In the plasma processing chamber 7, a roller 14 around which a sheet-like workpiece 13 is wound,
The take-up roller 15 that winds up the processed object to be processed is opposed to the winding roller 15, and the object to be processed 13 is arranged to face the window 7b.

[0004] The rectangular waveguide 8 for plasma chamber coupling is provided with a slot 8b extending in the tube axis direction on the E surface 8a. The slot 8b has a length substantially equal to the longitudinal direction of the window 7b of the plasma chamber 7, but its width is set smaller than the width of the window 7b. The coupling rectangular waveguide 8 is electrically connected with the slot 8 b facing the window 7 b of the plasma processing chamber 7.

The terminating device 9 is constituted by a microwave absorber that absorbs extra microwaves not supplied to the plasma processing chamber 7 side, and uses water as the microwave absorber. Extra microwaves that have not propagated to the plasma processing chamber 7 are absorbed by water introduced from the inlet 9a, and water heated by the microwaves is drained from the outlet 9b.

When performing the plasma processing using the above-described plasma processing apparatus, the object 13 to be processed is placed in the plasma processing chamber 7.
Is set, the inside of the plasma processing chamber 7 is brought into a high vacuum state. Thereafter, a predetermined process gas is supplied into the plasma processing chamber 7 from the process gas introduction pipe 12 until the pressure in the plasma processing chamber reaches a predetermined pressure. In this state, when microwaves are supplied from the microwave power supply 1 to one end of the rectangular waveguide 8 for plasma chamber coupling through the rectangular waveguide 4A on which the isolator 2, the directional coupler 3, and the impedance matching device 4 are mounted, the rectangular The microwaves that have entered the waveguide 8 are radiated from the slots 8b and are exposed to the windows 7b of the plasma processing chamber 7.
Through the plasma processing chamber 7, and converts the process gas in the plasma processing chamber into plasma.
A band-like plasma is generated along the window 7c. By irradiating the processing target 13 with the roller 15 while irradiating the processing target 13 with the plasma, processing over a wide area can be continuously performed.

In particular, if an electromagnet 10C is provided as a means for generating a magnetic field in the space between the window 7b of the plasma processing chamber 7 and the processing object 13, electrons and ions in the plasma receive a force due to the magnetic field. Make a spiral movement. As a result, the frequency of ionization and excitation of the reactive gas is increased, and the density of plasma applied to the object is increased. Further, by using, for example, permanent magnets 10B and 10C together so as to generate electron cyclotron resonance in the space,
The plasma density can be dramatically increased. Further, by setting the magnetic field to be a diverging magnetic field from the window 7b toward the center of the plasma processing chamber, the workpiece 13 can be efficiently irradiated with the plasma.

[0008]

In the plasma processing apparatus according to the prior art, the intensity of the microwave electric field radiated from the slot 8b having a length AB to the plasma processing chamber 7 is as shown in FIG. The distribution is non-uniform with peaks and valleys in the longitudinal direction. This is because the microwave radiated from the slot provided on the side wall of the waveguide forms a radiation pattern having strength corresponding to the free space wavelength. Therefore, although plasma with high uniformity is required, the distribution of generated plasma becomes non-uniform, and there is a problem in uniform processing over a wide area of an object to be processed.

Further, of the microwave power input to the rectangular waveguide for coupling to the plasma chamber 8, the power not radiated from the slot 8 b to the plasma processing chamber 7 passes through the rectangular waveguide 8 and terminates at the terminal device 9. Since all the power is consumed by the microwave absorber inside the device, there is a problem that the power use efficiency is low and the density of the generated plasma is low.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma processing apparatus capable of uniformly performing plasma processing on an object to be processed over a wide area and improving microwave power use efficiency as compared with the conventional example. Is to provide.

[0011]

SUMMARY OF THE INVENTION The present invention provides a microwave power supply, a rectangular waveguide for introducing microwaves output from the microwave power supply, and an elongated window on a side wall to face the window. And a plasma processing chamber in which the object to be processed is disposed, and microwaves introduced into the rectangular waveguide are radiated through the window to generate plasma, and perform predetermined processing on the object to be processed. It relates to a plasma processing apparatus.

According to the first aspect of the present invention, the microwave radiator is disposed such that the terminal radiator has an elongated terminal opening, and the terminal opening faces the window. A matching transformer is provided between them.

According to the first aspect of the present invention, there is no phenomenon that the intensity of the microwave electric field appears every half of the free space wavelength of the microwave, and a band-like plasma is generated along the window of the plasma processing chamber. be able to.

According to a second aspect of the present invention, the microwave radiator is constituted by a tapered waveguide, the H planes are formed parallel to each other, and both E planes are divergent along the traveling direction of the microwave. It has been formed.

[0015] In the invention of claim 2, by widening gradually the distance between the E-plane of the microwave emitter, it is propagated waves TE ₁₀ mode extends E plane direction to microwave radiation vessel it can.

According to a third aspect of the present invention, the microwave radiator is constituted by a multimode converter, and the power supply side rectangular waveguide portion and the load are separated by a discontinuous right angle portion formed on both E surfaces. The center axis of the power supply side rectangular waveguide section and the center axis of the load side rectangular waveguide section, and the length of the long side of the load side rectangular waveguide section. Is set to 3/2 or more of the free space wavelength λ ₀ of the microwave and the same length as the short side of the power supply side rectangular waveguide part and the short side of the load side rectangular waveguide part.

According to the third aspect of the present invention, a TE _m0 (m = 1, 3, 5,...) Mode microwave can be propagated through the load-side rectangular waveguide portion. The length of the load-side waveguide parts, for example, (λ _0/2) · 3 or more, (λ _0/2) If it is designed to be less than-5, and TE ₁₀ by microwave radiators T
At the same time it is possible to propagate into the plasma processing chamber a wave of the two modes of the E _30.

According to a fourth aspect of the present invention, a part of the microwave is reflected and the remaining microwave is absorbed so as to correspond to the portion where the electric field strength of the microwave is strong in the longitudinal direction of the terminal opening. A dielectric that allows transmission without transmission is arranged on the side of the terminal opening in the microwave radiator.

According to the fourth aspect of the present invention, the microwave propagating in the microwave radiator reflects a part of the microwave by the dielectric and propagates between the dielectric and the side wall of the microwave radiator. In addition, since the remaining microwaves propagate in the dielectric, the region where the electric field strength is originally strong is weakened, and the region where the electric field strength is weak near the E-plane of the microwave radiator is strengthened.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

<First Embodiment> FIG. 1 is an overall configuration diagram of a plasma processing apparatus showing a first embodiment according to the present invention. As shown in the figure, a matching transformer 5 and a microwave radiator 6 are provided between a rectangular waveguide 4A on which the impedance matching device 4 is mounted and the plasma processing chamber 7, and the matching transformer 5 is provided. Is located on the side of the rectangular waveguide 4A, and the microwave radiator 6 is located on the side of the plasma processing chamber 7. The same components as those in FIG. 12 are denoted by the same reference numerals.

FIG. 2 is a diagram showing a connection state between the matching transformer 5 and the microwave radiator 6. The matching transformer 5 includes, between two waveguides having different characteristic impedances, one or a plurality of waveguides having a predetermined characteristic impedance and having a length of a quarter of the waveguide wavelength λg of the microwave. This is a matching circuit for inserting and matching. In the present embodiment, a one-stage λg / 4 transformer is used as a matching circuit, and the power supply side connection rectangular waveguide 5A and the matching rectangular waveguide 5A are used.
B and a load-side connection rectangular waveguide 5C.

The characteristic impedance Z2 of the matching rectangular waveguide 5B is given by equation (1) as the geometric mean of the characteristic impedances Z1 and Z3 of the front and rear waveguides 5A and 5C.

Z 2 = (Z 1 · Z 3) ^1/2 (1)

As shown in FIG. 2, each waveguide 5
Assuming that the lengths of the short sides (heights between the H planes) of the inner walls of A, 5B, and 5C are b1, b2, and b3, the characteristic impedance of each waveguide can be defined by equation (2).

[0025]

(Equation 1)

[0026] Here, a is a common term in the case of the waveguide 5A, 5B, the long side length of the inner wall of 5C, Z _TE only microwave TE ₁₀ mode within the waveguide propagates.

From equations (1) and (2), the length b2 of the short side of the matching rectangular waveguide 5B is determined by equation (3).

B 2 = (b 1 · b 3) ^1/2 (3)

The microwave radiator 6 is formed of a tapered waveguide, is connected to the load-side connection rectangular waveguide 5C of the matching transformer 5, has its H faces formed in parallel, and Both E surfaces are formed so as to spread out in the direction in which the microwave travels, and furthermore, an elongated terminal opening 6a is formed. The length AB in the longitudinal direction of the terminal opening 6a is set in accordance with the processing width of the workpiece 13, and the height of the terminal opening 6a is set such that abnormal discharge does not occur in this portion.
In addition, it is set so that the maximum electric field strength is obtained.

In the plasma processing apparatus configured as described above, the microwave generated by the microwave power supply 1 is used for matching with the rectangular waveguide 4A on which the isolator 2, the directional coupler 3, and the impedance matching unit 4 are mounted. The microwave propagates through the microwave radiator 6 through the transformer 5, and is radiated from the terminal opening 6 a of the microwave radiator 6 and passes through the microwave transmission window 11 and the window 7 c to the plasma processing chamber 7. Propagate to

In this embodiment, the TE ₁₀ mode wave extending in the E-plane direction can be propagated in the microwave radiator 6 by gradually increasing the interval between the E-planes of the microwave radiator 6. it can.

The distribution of the microwave electric field strength between AB of the terminating opening 6a by the waves of the above TE ₁₀ mode is as shown in FIG. 3, due to the free space wavelength of the microwave shown in Figure 14 No valleys occur. Moreover, since microwave power is supplied to the plasma processing chamber 7 from the end of the waveguide, the microwave power is used with high efficiency and high-density plasma is generated.

<Second Embodiment> FIG. 4 shows a second embodiment according to the present invention and is a diagram showing a connection state between a matching transformer and a microwave radiator. As shown in the figure, the microwave radiator 16 is configured by a multi-mode converter, and is connected to the load-side connection rectangular waveguide 5C of the matching transformer 5. The matching transformer 5 has the same configuration as that of the first embodiment.

The microwave radiator 16 has an H surface (long side)
A discontinuous rectangular waveguide which is parallel to each other and has a right-angled portion on both E surfaces (short-side sides). It comprises a power-supply-side rectangular waveguide section 16A having a length b, and a load-side rectangular waveguide section 16B having a long side length a 'and a short side length b' of the inner wall. The long side of the load-side rectangular waveguide 16A is connected to the power-side rectangular waveguide 16B.
Is formed to be larger than the long side, and an elongated terminal opening 16a is formed. The length AB of the terminal opening 16a in the longitudinal direction is set in accordance with the processing width of the workpiece 13, and the height of the terminal opening 16a is set so that abnormal discharge does not occur in this portion and the maximum electric field intensity is obtained. Is set to obtain.

In this embodiment, the length b of the short side of the power supply side rectangular waveguide portion 16A and the length b 'of the short side of the load side rectangular waveguide portion 16B are set to be equal, and of the long sides of the waveguide portion 16B of the length a ', a microwave free-space wavelength lambda ₀ of the (λ _0/2) · 3 or more, yet the central axis and the load side of the power supply side conductor waveguide parts By matching the central axis of the rectangular waveguide section, the load-side rectangular waveguide section 16 can be formed.
A microwave in the TE _m0 (m = 1, 3, 5,...) Mode can be propagated to B. The load side waveguide parts 16B the length a ', for example (λ _0/2) · 3 or more, (λ _0/2) ·
If it is designed to be less than 5, T
It is possible to simultaneously propagated to the plasma processing chamber 7 waves of two modes of E ₁₀ and TE _30.

The distribution of the microwave electric field between the A and B of the terminal opening 6a by the wave obtained by combining the above two modes is as shown by the solid line in FIG. 5, and the distribution of the microwave electric field intensity is shown in FIG. becomes as shown by the 6 solid line, it is higher uniformity than the microwave field intensity by waves only TE ₁₀ mode which is a fundamental mode in the first embodiment. The dotted line shown in FIG. 5 shows the distribution of the microwave electric field due to the wave of TE ₁₀ and TE ₃₀ modes. Here, in the TE _m0 mode, a wave of even order m does not occur because the structure of the microwave radiator 16 is bilaterally symmetric.

<Third Embodiment> FIG. 7 shows a third embodiment according to the present invention, and shows a connection state between a matching transformer and a microwave radiator when applied to the first embodiment. FIG. As shown in the drawing, a solid dielectric 17 is disposed on the side of the terminal opening 6a in the microwave radiator 6.

The dielectric 17 is a substance that reflects a part of microwaves and transmits the remaining microwaves without absorbing them. The dielectric 17 is made of ceramic such as alumina or synthetic resin such as Teflon. Is formed.

In the present embodiment, the first microwave emitter 6 is the dielectric 17 will be described in the absence, by the wave of TE ₁₀ mode propagates, A of microwave emitter 6 illustrated in FIG. 8 The distribution of the microwave electric field intensity between "B", A'B 'and AB is shown in FIG.
As indicated by the dotted line.

Next, as shown in FIG. 8, the top of the mountain-shaped dielectric 17 is placed on the side of the microwave power source 1 at a position corresponding to the portion of the microwave radiator 6 where the microwave electric field strength is high between AB. , The microwave W1 reflected on the side wall of the microwave radiator 6 is partially reflected on the surface of the dielectric 17 to become a microwave W2,
The remaining microwaves pass through the dielectric 17 and pass through the microwave W
As 2 ', it reaches the terminal opening 6a of the microwave radiator 6. The microwave W2 reflected on the surface of the dielectric 17 is
Reflected on the side wall of the microwave radiator 6, the dielectric 17
Incident on. At this time, the microwave W2 is partially reflected on the surface of the dielectric 17 to become a microwave W3, and the remaining microwave is transmitted and reaches the terminal opening 6a of the microwave radiator 6 as a microwave W3 '. On the other hand, the reflected microwave W3 passes through the side wall of the microwave radiator 6 and finally reaches the terminal opening 6a of the microwave radiator 6. Therefore, the portion of the microwave electric field strength originally high becomes low, and conversely, the microwave reflected on the surface of the dielectric 17 is propagated to the portion of the microwave electric field strength originally low, thereby increasing the electric field strength. .

The microwave electric field strength between the TE ₁₀ mode microwave emitter 6 of A'B 'and between AB by wave distribution is as shown by the solid line in FIG. 9, respectively, in the second embodiment The uniformity is further improved as compared with the microwave electric field intensity, and the distribution becomes more uniform in the longitudinal direction.

<Fourth Embodiment> FIG. 10 shows a fourth embodiment according to the present invention, and is a view showing the inside of a microwave radiator when applied to the second embodiment. As shown in the figure, solid dielectrics 27A and 27B are arranged on the side of the terminal opening 16a in the microwave radiator 16.

The dielectrics 27A and 27B are materials that reflect a part of microwaves and transmit the remaining microwaves without absorbing them. The dielectrics 27A and 27B are made of ceramic such as alumina or synthetic resin such as Teflon. It is formed in a mountain shape.

[0044] In this embodiment, first microwave emitter 16 in the dielectric 27A, the case is described in which 27B is not present, by the waves of TE ₁₀ mode propagates, microwave emitter 16 shown in FIG. 10 The distribution of the microwave electric field intensity between A′B ′ and AB is as shown by the dotted line in FIG.

Next, as shown in FIG. 10, a mountain-shaped dielectric material 27 is provided at a position corresponding to the two strong portions of the microwave electric field strength between the AB of the microwave radiator 16.
The microwaves propagating in the microwave radiator 16 are partially reflected by the dielectrics 27A and 27B by inserting the A and 27B with the tops facing the microwave power supply 1 side. Since the microwaves propagate between the bodies 27A and 27B and the side walls of the microwave radiator 16 and the remaining microwaves pass through the dielectrics 27A and 27B, the region where the electric field intensity is originally high is weakened, and the microwave radiator is weakened. 16
The region near the E-plane where the electric field strength is weak is strengthened.

The distribution of the microwave electric field strength between A'B 'and between AB of the microwave emitter 16 according to waves of TE ₁₀ mode is as shown by the solid line in FIG. 11, respectively, third
As compared with the microwave electric field intensity in the embodiment, the uniformity is further enhanced, and the distribution becomes substantially uniform in the longitudinal direction.

In each of the above embodiments, the electromagnet 10 A and the permanent magnet 1
When 0B and 10C are provided, the frequency of ionization and excitation of the reactive gas is increased, and the density of plasma applied to the object to be processed is increased. Further, by setting the magnetic field so as to be a divergent magnetic field from the window 7b toward the center of the plasma processing chamber, the workpiece 13 can be efficiently irradiated with the plasma.

The shape of the dielectric used in the above embodiment is not limited to a mountain shape, but may be, for example, a trapezoid, a triangle, or a rectangle, and the shape may be appropriately changed according to processing conditions. I just need.

[0049]

As described above, according to the first and second aspects of the present invention, the end portion of the waveguide is a microwave radiator, and the microwave radiator is provided with an elongated terminal opening. Therefore, there is no phenomenon in which the strength of the microwave electric field appears every half of the free space wavelength of the microwave caused by providing the slot in the side wall of the waveguide, and a long and narrow microwave electric field strength distribution can be obtained. it can. Further, since the efficiency of using microwave power is improved, the density of generated plasma is increased. Therefore, by moving the processing object while irradiating the linear plasma, plasma processing can be performed on a large area at high speed.

Further, according to the third aspect of the present invention, TE ₁₀
Uniformity can be improved as compared with the microwave electric field intensity due to the mode-only wave.

According to the fourth aspect of the present invention, the distribution of the microwave electric field over the longitudinal direction of the terminal opening of the microwave radiator can be made substantially uniform. A part of the microwave is reflected inside the microwave radiating part, a part of the microwave is transmitted, and a dielectric that does not absorb the microwave is placed in the part where the microwave electric field strength is strong, so that the strong part is weakened. On the contrary, the weak part is compensated by the power reflected from the dielectric, and the power of the microwave radiated to the plasma chamber can be made uniform along the longitudinal direction of the window of the plasma chamber. The plasma density can be made uniform.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a plasma processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a connection state between the matching transformer of FIG. 1 and a microwave radiator.

FIG. 3 is a diagram showing a distribution of a microwave electric field strength in a longitudinal direction of a terminal opening of the microwave radiator according to the first embodiment of the present invention.

FIG. 4 is a view showing a second embodiment according to the present invention, and showing a connection state between a matching transformer and a microwave radiator.

FIG. 5 is a diagram showing a distribution of a microwave electric field in a longitudinal direction of a terminal opening of a microwave radiator according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a distribution of a microwave electric field intensity in a longitudinal direction of a terminal opening of a microwave radiator according to a second embodiment of the present invention.

FIG. 7 shows a third embodiment according to the present invention, and is a diagram showing a connection state between a matching transformer and a microwave radiator when applied to the first embodiment.

FIG. 8 is a diagram showing the inside of the microwave radiator of FIG. 7;

FIG. 9 is a diagram showing the microwave radiator shown in FIG.
It is a figure which shows the distribution of the microwave electric field intensity between B 'and between AB.

FIG. 10 shows a fourth embodiment according to the present invention, and is a view showing the inside of a microwave radiator when applied to the second embodiment.

11 is a diagram showing distributions of microwave electric field intensity between A'B 'and between AB of the microwave radiator shown in FIG. 10;

FIG. 12 is an overall configuration diagram of a conventional plasma processing apparatus.

FIG. 13 is a sectional view taken along the line II of FIG. 12;

14 is a diagram showing a distribution of microwave electric field strength in a longitudinal direction of the slot in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microwave power supply 5 Matching transformer 6, 16 Microwave radiator 6a, 16a Termination opening 17, 27A, 27B Dielectric

Claims (4)

[Claims] 1. A microwave power supply, a rectangular waveguide for introducing microwaves output from the microwave power supply, and an elongated window provided on a side wall, and an object to be processed is disposed so as to face the window. A plasma processing chamber, wherein the microwave introduced into the rectangular waveguide is radiated through the window to generate plasma, and performs predetermined processing on the object to be processed. A microwave radiator having an elongated terminal opening, wherein the terminal opening faces the window, and a matching transformer is provided between the rectangular waveguide and the microwave radiator; Plasma processing equipment. 2. The microwave radiator is constituted by a tapered waveguide, H planes are formed in parallel, and both E planes are formed.
2. The plasma processing apparatus according to claim 1, wherein the surface is formed in a divergent shape along the traveling direction of the microwave. 3. The microwave radiator is constituted by a multi-mode converter, and a power supply side rectangular waveguide part and a load side rectangular waveguide part are bordered by discontinuous right-angled portions formed on both E surfaces. The central axis of the power-side rectangular waveguide portion and the central axis of the load-side rectangular waveguide portion coincide with each other, and the length of the long side of the load-side rectangular waveguide portion is set to 2. The plasma processing according to claim 1, wherein the length is equal to or more than 3/2 of the free space wavelength λ ₀ , and the length of the short side of the power supply side rectangular waveguide is equal to the length of the short side of the load side rectangular waveguide. apparatus. 4. A dielectric which reflects a part of the microwave and transmits the remaining microwave without absorbing it so as to correspond to a portion where the electric field strength of the microwave is strong in the longitudinal direction of the terminal opening. The plasma processing apparatus according to claim 2, wherein the plasma processing apparatus is disposed on a terminal opening side in the microwave radiator.