JPH07211488A - Device and method for plasma processing - Google Patents

Abstract

PURPOSE:To provide a device and a method for plasma processing whereby a uniform thin film can be formed over a substrate with a large area at high speed. CONSTITUTION:A linear antenna 2 is connected to a coaxial connector 1. A pipe through which a cooling medium passes and a pipe through which a reaction gas passes are provided inside the linear antenna, and a plurality of gas ejecting holes are bored in the surface of the linear antenna 2. A pair of permanent magnets 4a, 5b held by a yoke 5 are disposed below the linear antenna 2. A tapped hole is provided in the yoke 5 and a ball screw 6 is passed through the tapped hole. The ball screw 6 is supported on a pedestal 7 at one end and connected to a motor 8 at the other end. A substrate 3 is disposed between the liner antenna 2 and each permanet magnet 4a, 4b and moved in the direction of arrow A. These component members are enclosed in a vacuum tank provided in such a way as to surround the substrate 3, and the vacuum tank is provided with an exhaust pump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to plasma CVD for forming large area thin films used in various electronic devices such as amorphous silicon solar cells, thin film semiconductors and photosensors.
The present invention relates to a plasma processing apparatus and a processing method that can be used as a (chemical vapor deposition) apparatus or an etching apparatus.

[0002]

2. Description of the Related Art In recent years, a technique of using a microwave and a magnetic field in a CVD apparatus to form a film on a large-area substrate at high speed has been used for amorphous silicon and the like. For example,
A plasma processing device of diffusion electron cyclotron resonance in which a plasma is spread using a linear antenna and a multipole magnetic field configuration has been proposed (for example, M.Pichot, A. Durandet, J. Pelletie).
Rev. Sci, Instrum. 59 (7), July of r, Y. Arnal, L. Vallier et al.
1988 `` Microwave multipolar plasmas exited by distri
buted electron cyclotron resonance: Concept and per
formance ”), deposition and etching.

However, this method has a problem that the plasma density in the film forming region is low and the film forming speed is slow because the diffusion plasma is used. Further, if the gas pressure is increased in order to increase the film formation rate, there is a problem in that the uniformity decreases.

Therefore, in order to solve such a problem, a microwave plasma processing apparatus as shown in FIGS. 5 and 6 has been proposed. FIG. 5 is a perspective view showing a conventional microwave plasma processing apparatus, and FIG. 6 is a sectional view of FIG. In FIGS. 5 and 6, reference numeral 31 is a coaxial connector, and a linear antenna 32 is connected to the coaxial connector 31. A rectangular substrate 33 is arranged below the linear antenna 32, and a permanent magnet 35 held by a yoke 34 is arranged below the rectangular substrate 33. Here, the permanent magnet 35 is composed of a rod-shaped permanent magnet 35a parallel to the linear antenna 32 and a permanent magnet 35b surrounding the permanent magnet 35a at equal intervals. The permanent magnets 35a and 35b are magnetized where they face the rectangular substrate 33, and the permanent magnet 35a has an S pole and the permanent magnet 35b has an N pole.

In the above structure, the rectangular substrate 33
For example, a non-magnetic stainless substrate with a thickness of 1 mm is used, and the distance between the permanent magnet 35 and the rectangular substrate 33 is, for example, 5 m.
When set to m, a toroidal tunnel magnetic field 36 is generated on the rectangular substrate 33 (see FIG. 6). As shown in FIG. 6, the tunnel magnetic field 36 is generated by the permanent magnets 35a and 35b.
It occurs in the middle and becomes a closed path of an ellipse. A part of the electric field 37 generated by the linear antenna 32 is orthogonal to the tunnel magnetic field 36. Therefore, the electrons generated in the discharge region can be trapped in the magnetic tunnel to cause magnetron discharge. In addition, Co-
If Sn is used, a magnetic field of 875 G is generated 4 mm above the rectangular substrate 33, and the electron cyclotron resonance (ECR) condition can be satisfied for the microwave of 2.45 GHz. Then, if argon gas of 10 ⁻⁴ Torr level is introduced there, the density is 10 ¹⁰ to 10 ¹¹ cm.
^-3 argon gas plasma can be generated.

Further, if the square substrate 33 is heated to 300 ° C. by the infrared lamp 30 and SiH ₄ gas is introduced instead of the argon gas, an amorphous silicon film can be formed on the square substrate 33. .

[0007]

However, in the conventional microwave plasma processing apparatus having the above structure,
Increasing the gas pressure to increase the film formation speed (5 mTo
However, there is a problem in that plasma is concentratedly discharged at the exit of the coaxial cable (at the base of the antenna) and cannot be discharged over a wide range. Therefore, when the amorphous silicon film is formed by introducing SiH ₄ gas, the film quality in the longitudinal direction of the antenna becomes non-uniform and it is difficult to increase the area.

In order to solve the above-mentioned problems of the prior art, it is an object of the present invention to provide a plasma processing apparatus and a processing method capable of forming a uniform thin film at a high speed on a large-area substrate.

[0009]

In order to achieve the above object, a plasma processing apparatus according to the present invention has a structure in which a vacuum chamber whose inside is held in a depressurized state and a unit which holds a processing substrate in the vacuum chamber. A means for introducing a reaction gas into the vacuum chamber, a means for exhausting the vacuum chamber, a connecting means for introducing microwave power into the vacuum chamber, and an antenna attached to the connecting means. It is provided with at least magnetic field generating means for generating a magnetic field in the electric field region radiated by the antenna, and means for changing the intensity distribution of the magnetic field.

Further, in the above-mentioned structure, the means for changing the intensity distribution of the magnetic field changes the intensity distribution of the magnetic field in the longitudinal direction of the antenna by moving the magnetic field generating means in the vicinity of the outside of the antenna. Is preferred.

Further, in the above structure, the means for changing the intensity distribution of the magnetic field changes the intensity distribution of the magnetic field in the longitudinal direction of the antenna by moving the magnetic field generating means inside the antenna. preferable.

Further, in the above structure, the magnetic field generating means is a plurality of electromagnets arranged outside the antenna, and the means for changing the intensity distribution of the magnetic field changes the current applied to the electromagnets, thereby changing the antenna. It is preferable that the intensity distribution of the magnetic field is changed in the longitudinal direction of.

Further, in the above structure, the microwave is preferably 2.45 GHz. Further, in the above structure, the magnetic field strength is 875 between the substrate and the antenna.
It is preferable that there is a point of G.

The plasma processing method according to the present invention is
A vacuum chamber whose inside is held in a reduced pressure state, a unit for holding a processing substrate in the vacuum chamber, a unit for introducing a reaction gas into the vacuum chamber, a unit for exhausting the inside of the vacuum chamber, and the vacuum chamber. At least a connection means for introducing microwave power into the tank, an antenna attached to the connection means, and a magnetic field generation means installed in the vicinity of the antenna are provided, and an electric field radiated from the antenna and the magnetic field generation means. A plasma processing method for processing the substrate by generating plasma by interaction with a magnetic field from
The substrate is processed by changing the intensity distribution of the magnetic field in the longitudinal direction of the antenna and generating the plasma in a wide range along the antenna.

[0015]

According to the structure of the present invention, the reaction gas is introduced into the vacuum chamber, and the interaction between the electric field of the microwave radiated from the antenna and the magnetic field from the magnetic field generating means causes electron cyclotron resonance (ECR). Plasma can be generated. In this case, since the place where plasma is generated moves due to the change in the intensity distribution of the magnetic field, it is possible to generate uniform plasma over a wide range. Therefore,
By moving the substrate with respect to the antenna, a uniform thin film can be formed at a high speed on a large-area substrate. Further, by setting the reaction gas to a gas suitable for etching, it is possible to uniformly perform the etching process on a large-area substrate.

Further, according to the structure of the method of the present invention, since the plasma is generated in a wide range along the antenna, by moving the substrate in the direction perpendicular to the antenna, a large-area substrate can be made uniform. Can be processed efficiently.

[0017]

EXAMPLES The present invention will be described in more detail below with reference to examples. (Embodiment 1) FIG. 1 is a perspective view showing an embodiment of the plasma processing apparatus according to the present invention. In FIG. 1, reference numeral 1 is a coaxial connector, and a linear antenna 2 is connected to the coaxial connector 1. Thereby, a microwave of, for example, 2.45 GHz can be guided from the coaxial connector 1 to the linear antenna 2. Inside the linear antenna 2, a pipe through which a cooling medium passes and a pipe through which a reaction gas passes are provided, and a plurality of gas ejection holes are formed on the surface of the linear antenna 2 (Fig. (Not shown). Linear antenna 2
A pair of permanent magnets 4a, 4a held by a yoke 5 is provided on the lower side of
b is arranged, the permanent magnet 4a is an N pole, and the permanent magnet 4 is
b is the south pole. The yoke 5 is provided with a tap hole, and a ball screw 6 is passed through the tap hole. The ball screw 6 is arranged in parallel with the linear antenna 2, one end of which is supported by the pedestal 7, and the other end of which is connected to the motor 8. Accordingly, when the motor 8 is rotated, the ball screw 6 is rotated, and the permanent magnets 4a and 4b can be linearly moved along the ball screw 6. A width 280 is provided between the linear antenna 2 and the permanent magnets 4a and 4b.
A mm substrate 3 is arranged so that it can be moved in the direction of arrow A.

The components described above are housed inside a vacuum chamber (not shown) provided so as to surround the substrate 3, and the vacuum chamber is provided with an exhaust pump (not shown). In FIG. 1, 9 is an infrared heater for heating the substrate 3.

In the plasma processing apparatus having the above structure, first, the coaxial connector 1 is set to 2.45 GHz.
Of the microwave of 300 W is introduced and radiated from the linear antenna 2, and SiH is supplied to the linear antenna 2 as a reaction gas.
Introduce ₄ gas at 50 mTorr level. In this case, if Co-Sm is used for the permanent magnets 4a and 4b and a magnetic force is generated between the substrate 3 and the linear antenna 2 so as to generate a region having a magnetic field strength of 875 G, a micro wave of 2.45 GHz is generated. A magnetic field that satisfies the electron cyclotron resonance (ECR) condition is generated for the wave, and due to the interaction between the microwave radiated electric field and the magnetic field, a high density SiH of 10 ¹¹ cm ^-3 is generated.
₄ Plasma is generated. In addition, the length of the linear antenna 2 is 300 mm and the length of the ball screw 6 is 400 mm,
The motor 8 is rotated at 1000 rpm, the permanent magnet 4a,
If the rotation direction of the motor 8 is switched so that one round trip of 4b is 0.4 sec, SiH ₄ plasma spreads in the longitudinal direction of the linear antenna 2 as the permanent magnets 4a, 4b move, and is uniform over a large area. Plasma can be generated.

If the distance between the permanent magnets 4a and 4b and the linear antenna 2 is set to 20 mm and the substrate 3 heated to about 300 ° C. by the infrared heater 9 is inserted between them, the amorphous silicon is placed on the substrate 3. The film can be deposited. In this case, if the substrate 3 is moved in the direction of arrow A at a speed of 1 mm / s, the film quality uniformity is ± 7%.
In the following, an amorphous silicon film having a thickness of about 0.5 μm can be deposited on the entire surface of the substrate 3.

(Embodiment 2) FIG. 2 is a perspective view showing another embodiment of the plasma processing apparatus according to the present invention. In FIG. 2, 10 is a coaxial waveguide, and this coaxial waveguide 10 is connected to a rectangular waveguide 13. Reference numeral 11 denotes a linear antenna. One end of the linear antenna 11 penetrates the rectangular waveguide 13 and projects to the outside, and the other end crosses the inside of the vacuum chamber 17 and projects to the outside. Thereby, for example, microwave power of 2.45 GHz can be introduced from the arrow B side of the rectangular waveguide 13 and guided to the linear antenna 11. The coaxial waveguide 10 is vacuum-sealed with ceramics. The linear antenna 11 has a hollow structure, and a plurality of bar magnets 18 are housed therein in a freely movable state. An air inlet 12 is connected to both ends of the linear antenna 11, and the air inlet 1
The compressed air can be sent into the inside of the linear antenna 11 from 2. As a result, the flow of air into and out of both air inlets 12, 12 is switched, and the bar magnet 1
8 can be reciprocated inside the linear antenna 11. The bar magnet 18 is formed in a cylindrical shape, and both ends thereof are magnetized. For example, when the bar magnets 18 are arranged so as to repel each other as shown in FIG. 2, as many magnetic fields as the bar magnets 18 can be generated. Reference numeral 19 is a stopper that restricts the movement of the bar magnet, and two stoppers are provided in accordance with the position of the end of the vacuum chamber 17. The vacuum chamber 17 is provided with an exhaust pump (not shown) and has a width of 400
A long and thin hole is formed in the front and back so that the mm substrate 14 can pass through from the outside. Substrate 14 is infrared heater 1
After being heated by 5, it can pass through the vacuum chamber 17 and move in the direction of arrow C. A gas introducing pipe 16 is arranged inside the vacuum chamber 17 in parallel with the linear antenna 11, and a plurality of gas ejection holes are formed on the surface of the gas introducing pipe 16.

In the plasma processing apparatus having the above structure, first, a microwave of 2.45 GHz, 500 W, is introduced into the rectangular waveguide 13 and radiated from the linear antenna 11 through the coaxial waveguide 10. On the other hand, SiH ₄ gas is introduced as a reaction gas from the gas introduction pipe 16 and the inside of the vacuum chamber 17 is maintained at 40 mTorr. in this case,
If Co-Sm is used for the permanent magnet 18 and a magnetic force is generated between the substrate 14 and the linear antenna 11 so as to generate a region having a magnetic field strength of 875 G, ECR with respect to a microwave of 2.45 GHz is obtained. A magnetic field satisfying the conditions is generated, and the interaction between the radiated electric field of the microwave and the magnetic field causes a high density Si of 10 ¹¹ cm ^{−3 in} the vicinity of the permanent magnet 18.
H ₄ plasma is generated. In addition, the air inlets 12 and 12 connected to both ends of the linear antenna 11 from 6 kg /
Alternately send compressed air of cm ² and set permanent magnet 18 to 1
If you move 450 mm in a cycle of 0.2 msec round trip,
With the movement of the permanent magnet 18, the SiH ₄ plasma spreads in the longitudinal direction of the linear antenna 11, and a large area and uniform plasma can be generated.

The substrate 14 has a thickness of 1 mm, for example.
The amorphous silicon film can be deposited on the substrate 14 by heating the substrate 14 to about 300 ° C. by the infrared heater 15 using the non-magnetic stainless steel plate.
In addition, the substrate 14 is vacuum chamber 17 at a speed of 2 mm / s, for example.
By passing through the inside, an amorphous silicon film having a thickness of about 0.6 μm can be deposited on the entire surface of the substrate 14 within a film quality uniformity of ± 5%.

(Embodiment 3) FIG. 3 is a schematic view showing still another embodiment of the plasma processing apparatus according to the present invention. Figure 3
In the figure, 23 is a coaxial connector, and a linear antenna 24 is connected to the coaxial connector 23.
Outside the linear antenna 24, ring-shaped electromagnets 20a, 20b, 20c are arranged as magnetic field generating means. Since the other configurations are similar to those of the first embodiment, the description thereof will be omitted.

In the plasma processing apparatus having the above structure, the coaxial connector 23 has an outer diameter of 20 mm, the linear antenna 24 has an outer diameter of 5 mm, and a length of 450 mm.
The inner diameter of the electromagnets 20a, 20b, 20c is 200 mm, the number of turns is 1000, and the electromagnets 20a, 20b, 20c are 2
It is arranged at intervals of 00 mm. Then, the electromagnets 20a, 2
If a direct current of 10 A is applied to 0b and 20c, a magnetic field of about 1000 G can be generated in the vicinity of the linear antenna 24 in the direction of the arrow in FIG.

Further, in accordance with the timing chart shown in FIG. 4, the electromagnets 20a, 20b and 20c each have 10 ms.
If a current is passed with a time width of ec, 20 msec, 40 msec, a magnetic field that sequentially moves in the longitudinal direction of the linear antenna 24 can be generated and controlled.

At this time, the coaxial connector 23 receives 2.45.
If microwave of 200 GHz and 200 W are introduced and radiated from the linear antenna 24 and SiH ₄ gas of 50 mTorr is introduced into the linear antenna 24 as a reactive gas, 10 ¹¹ cm ⁻³ SiH of SiH ₄ gas is provided in the vicinity of the antenna 24. ₄ Plasma is generated. Further, if an electric current is applied according to the timing chart of FIG. 4, the SiH ₄ plasma spreads in the longitudinal direction of the linear antenna 24 with the movement of the magnetic field, and a large area and uniform plasma can be generated. Then, if a substrate heated to about 300 ° C. is installed near the linear antenna 24, an amorphous silicon film can be uniformly deposited on the substrate as in the first and second embodiments.

In the third embodiment, a pulse-shaped control signal is used to change the time width of the electric current applied to each of the electromagnets 20a, 20b, 20c so that the linear antenna 24 can be moved sequentially in the longitudinal direction. The magnetic field is generated, but the magnetic field is not necessarily limited to this configuration, and the linear antenna 24 is sequentially moved in the longitudinal direction by performing phase difference control using a three-phase alternating current, for example. A magnetic field can be generated.

Further, in the above-mentioned first, second and third embodiments,
Although the case where the plasma processing apparatus is used as a film forming apparatus has been described as an example, the plasma processing apparatus is not necessarily limited to this application, and for example, by introducing a gas having the same configuration and suitable for etching, a large area can be obtained. It can also be used when the substrate is uniformly etched, and can be widely applied as a plasma processing apparatus.

[0030]

As described above, according to the plasma processing apparatus of the present invention, the reaction gas is introduced into the vacuum chamber and the electric field of the microwave radiated from the antenna and the magnetic field from the magnetic field generating means are generated. The interaction can generate an electron cyclotron resonance (ECR) plasma. In this case, because the intensity distribution of the magnetic field changes,
Since the plasma generation location moves, uniform plasma can be generated in a wide range. Therefore, if the substrate is moved with respect to the antenna, a uniform thin film can be formed at a high speed on a large-area substrate, and productivity can be improved. Further, by setting the reaction gas to a gas suitable for etching, it is possible to uniformly perform the etching process on a large-area substrate. Further, since the structure is simple, the maintenance cost, the production cost, and the like can be reduced, which is an excellent effect.

Further, according to the structure of the method of the present invention, since the plasma is generated in a wide range along the antenna, the substrate having a large area can be made uniform by moving the substrate in the direction perpendicular to the antenna. Can be processed efficiently.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing another embodiment of the plasma processing apparatus according to the present invention.

FIG. 3 is a schematic view showing still another embodiment of the plasma processing apparatus according to the present invention.

FIG. 4 is a diagram showing a magnetic field control timing chart of one embodiment of the plasma processing apparatus according to the present invention.

FIG. 5 is a perspective view showing a conventional plasma processing apparatus.

6 is a cross-sectional view of FIG.

[Explanation of symbols]

 1, 10, 23 Coaxial waveguide 2, 11, 24 Linear antenna 3, 14 Substrate 4a, 4b, 18 Permanent magnet 5 Yoke 6 Ball screw 7 Pedestal 8 Motor 9, 15 Infrared heater 13 Square waveguide 16 Gas introduction pipe 17 Vacuum tank 20a, 20b, 20c Electromagnet

Front page continuation (72) Inventor Shinichi Mizuguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A vacuum chamber whose inside is maintained in a depressurized state,
Means for holding the processing substrate in the vacuum chamber, means for introducing a reaction gas into the vacuum chamber, means for exhausting the vacuum chamber, and connecting means for introducing microwave power into the vacuum chamber. An antenna attached to the connecting means,
A plasma processing apparatus comprising at least magnetic field generating means for generating a magnetic field in an electric field region radiated by the antenna, and means for changing the intensity distribution of the magnetic field. 2. The means for changing the intensity distribution of the magnetic field is to change the intensity distribution of the magnetic field in the longitudinal direction of the antenna by moving the magnetic field generating means near the outside of the antenna. Plasma processing equipment. 3. The plasma according to claim 1, wherein the means for changing the intensity distribution of the magnetic field changes the intensity distribution of the magnetic field in the longitudinal direction of the antenna by moving the magnetic field generating means inside the antenna. Processing equipment. 4. The magnetic field generating means is a plurality of electromagnets arranged outside the antenna, and the means for changing the intensity distribution of the magnetic field changes the current applied to the electromagnets to thereby generate a magnetic field in the longitudinal direction of the antenna. 2. The plasma processing apparatus according to claim 1, wherein the intensity distribution is changed. 5. The plasma processing apparatus according to claim 1, wherein the microwave is 2.45 GHz. 6. The magnetic field strength is 8 between the substrate and the antenna.
The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus has a size of 75G. 7. A vacuum chamber whose inside is maintained in a reduced pressure state,
Means for holding the processing substrate in the vacuum chamber, means for introducing a reaction gas into the vacuum chamber, means for exhausting the vacuum chamber, and connecting means for introducing microwave power into the vacuum chamber. An antenna attached to the connecting means,
A plasma processing method, comprising: at least a magnetic field generating means installed in the vicinity of the antenna, wherein the substrate is processed by generating a plasma by an interaction between an electric field emitted from the antenna and a magnetic field from the magnetic field generating means. The plasma processing method is characterized in that the substrate is processed by changing the intensity distribution of the magnetic field in the longitudinal direction of the antenna to generate the plasma in a wide range along the antenna.