JP3092383B2 - Microwave plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma processing apparatus, and more particularly to a microwave plasma processing apparatus used as, for example, an etching apparatus for semiconductor element substrates, an ashing apparatus, a thin film forming processing apparatus, and the like.

[0002]

2. Description of the Related Art In an LSI manufacturing process, various processes are often performed using plasma generated when energy is externally applied to a reaction gas. In particular, dry etching technology using plasma
It has become an indispensable basic technology in the SI manufacturing process.

[0003] Generally, as excitation means for generating plasma, a microwave is used and an RF (Radio F) is used.
requency). When microwaves are used, plasma is obtained at a lower temperature and higher density than when RF is used, and there are advantages such as a simpler configuration and operation of the apparatus. However, in a conventional plasma apparatus using microwaves, it is difficult to uniformly process a large-diameter semiconductor substrate because the plasma generation region is small and it is difficult to generate plasma uniformly.

As an apparatus capable of generating microwave plasma uniformly with a wide plasma generation area,
A method using a dielectric line is known (Japanese Patent Application Laid-Open Nos. Sho 62-5600 and 62-99481).

FIG. 4 is a cross-sectional view schematically showing a microwave plasma processing apparatus of this type. In the figure, reference numeral 10 denotes a hollow rectangular parallelepiped reactor. The reactor 10 is formed using a metal such as Al, and a cooling water passage 11 through which cooling water flows is formed therein. A reaction chamber surrounded by a reaction chamber side wall 12 a is formed inside the cooling water passage 11. 12 are formed. The upper part of the reactor 10 is hermetically sealed by a microwave introduction window 13. The microwave introduction window 13 has heat resistance and microwave transparency, and has a small dielectric loss, such as quartz glass and Al ₂ O _3. And the like. In the reaction chamber 12, a sample stage 14 for mounting the sample S is provided at a position facing the microwave introduction window 13, and a lower wall of the reactor 10 is connected to an exhaust device (not shown). A gas supply pipe 16 for supplying a required reaction gas to the reaction chamber 12 is connected to one side wall of the reactor 10.

On the other hand, a dielectric line 20 made of fluororesin or the like having a small dielectric loss is disposed above the reactor 10, and a cover 21 is provided outside the dielectric line 20 so as to cover the dielectric line 20. Is provided, and the lid 21 is formed using Al or the like. A waveguide 22 is provided on the dielectric line 20.
Is connected to the waveguide 22, and a microwave oscillator 23 is connected to the waveguide 22. The microwave oscillated from the microwave oscillator 23 is introduced into the dielectric line 20.

When etching is performed on the surface of the sample S placed on the sample stage 14 by using the plasma apparatus configured as described above, first, cooling water is circulated through the cooling water passage 11, and then the exhaust port is exhausted. Exhaust gas from the reaction chamber 12
Is set to a required degree of vacuum, and then a reaction gas is supplied from the gas supply pipe 16. Next, a microwave is oscillated using the microwave oscillator 23 and is introduced into the dielectric line 20 via the waveguide 22. Then, an electric field is formed below the dielectric line 20, and the formed electric field passes through the microwave introduction window 13 and is supplied to the reaction chamber 12 to generate plasma.
This plasma is guided to the surface of the sample S, and etches the surface of the sample S.

[0008]

The microwave plasma processing apparatus described above has a problem that it is difficult to generate plasma at a low pressure of 10 mTorr or less, and processing such as etching becomes difficult. Further, in order to generate plasma under a low pressure, a microwave having a large power is supplied, and there is a problem that the energy efficiency regarding the generation of plasma is not very good.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and enables stable and high-density plasma generation without lowering energy efficiency even under low pressure. It is an object of the present invention to provide a microwave plasma processing apparatus capable of performing high-speed processing at a low temperature.

[0010]

In order to achieve the above object, a microwave plasma processing apparatus according to the present invention comprises a microwave oscillator, a waveguide for transmitting microwaves, and a waveguide connected to the waveguide. In a microwave plasma processing apparatus comprising: a dielectric line, a reactor having a microwave introduction window disposed opposite to the dielectric line, and a sample table independently provided in the reactor, At a position facing the microwave introduction window around the table, a reflection plate for confining the microwave electric field between the microwave introduction window and an exhaust hole having a diameter not larger than the hole diameter forming a non-propagating mode is provided. It is characterized by being arranged.

[0011]

According to the microwave plasma processing apparatus of the present invention, an exhaust hole having a diameter equal to or smaller than a hole diameter for forming a non-propagating mode is provided at a position around the sample stage facing the microwave introduction window,
Since the reflector for confining the microwave electric field between the microwave introduction window and the microwave introduction window is provided, gas is exhausted through the exhaust holes, and the microwave electric field is reduced by the microwave introduction window and the microwave introduction window. Since the plasma is securely trapped between the reflector and the electric field in the reactor, the plasma can be generated uniformly and stably even under a low pressure, and the plasma density can be increased.
In addition, since the sample stage is included in the plasma generation region, the high-density plasma enables high-speed and uniform processing of the sample without lowering the energy efficiency even under low pressure.

[0012]

Embodiment and Comparative Example FIG. 1A is a schematic sectional view showing a reference example of a microwave plasma processing apparatus according to the present invention. The configuration of the device shown in FIG.
Since this is the same as the conventional microwave plasma processing apparatus shown in FIG. 1, its detailed description is omitted here, and only the configuration different from that of the conventional apparatus is described. Note that components having the same functions as those of the conventional example are denoted by the same reference numerals.

The reaction chamber 12 is provided with a sample stage 14 on which a sample S is placed at a position opposed to the microwave introduction window 13, and a reflection plate 31 made of Al is provided around the sample stage 14.
Is provided, and the upper surface of the sample stage 14 and the upper surface of the reflector 31 are set at substantially the same level. As shown in FIG. 1B, the reflection plate 31 is formed in a substantially rectangular shape, and a hole 14a into which the sample table 14 can be inserted is provided substantially in the center of the reflection plate 31.
Are formed. The reflection plate 31 is fixed to a predetermined height of the reaction chamber side wall 12a such that an exhaust port 31a is formed at one end thereof.

When an etching process is performed on the sample S placed on the sample stage 14 by using the apparatus configured as described above, first, cooling water is circulated through the cooling water passage 11, and exhaust gas is exhausted from the exhaust port 15. Then, the reaction chamber 12 is set to a required degree of vacuum. Next, the reaction chamber 12 is set at a predetermined pressure while supplying gas from the gas supply pipe 16 and exhausting the gas through the exhaust port 31 a of the reflection plate 31. Next, a microwave is oscillated using the microwave oscillator 23, and the microwave is
The electric field formed below the dielectric line 20 is introduced into the reaction chamber 12 through the microwave introduction window 13. Then, the microwave electric field is reflected by the reflector 31 and is confined between the microwave introduction window 13 and the reflector 31 to form a high electric field. This electric field stably generates plasma and increases the plasma density, and this plasma is guided to the surface of the sample S to etch the surface of the sample S.

Hereinafter, a description will be given of the results of measurement of the plasma generation state and the ion current density distribution above the sample table 14 using the apparatus according to the reference example . The reflection plate 31 used had a size of 250 mm × 300 mm so that an exhaust port 31 a of 50 mm × 300 mm was formed at one end. As a comparative example, a conventional device in which the reflection plate 31 was not provided was used.

The detailed setting conditions and measuring conditions of the apparatus are shown below. (1) The dielectric line 20 is 20 mm thick and 500 m long
m, a fluororesin having a width of 300 mm was used. (2) Ar is used as the gas, and the gas flow rate is 100 sc
cm. (3) The microwave power was set to 1300W. (4) The ion current density was measured by setting the measuring probe 50 mm below the microwave introduction window 13 and moving the sample stage 14 in the Z direction shown in FIG. (5) The pressure at the time of measuring the plasma generation state is 1,
It was set to 2, 5, and 10 mTorr. (6) The pressure when measuring the ion current density is 10 mT
orr.

The state of plasma generation is shown in Table 1 below.
FIG. 3 shows the measurement results of the ion current density distribution.

[0018]

[Table 1] As is clear from Table 1, in the case of the comparative example, when the pressure is increased to 10 mTorr, the plasma is stably generated. However, in the case of the reference example , even if the pressure is reduced to 2 mTorr, plasma can be stably generated. Further, as apparent from FIG. 3, the average ion current density in the case of those of Comparative Example, but was 14 mA / cm ^2, reference
In the case of the example , it could be increased to 18 mA / cm ² and plasma could be generated uniformly.

As described above, in the microwave plasma processing apparatus according to the reference example , the exhaust port 31 is provided at the end of the periphery of the sample table 14 facing the microwave introduction window 13.
Since the reflection plate 31 is provided so as to form a, the gas can be exhausted through the exhaust port 31a, and the microwave electric field is confined between the microwave introduction window 13 and the reflection plate 31. Since the plasma generation region can be narrowed, the electric field strength can be increased, plasma can be stably generated even under a low pressure, and the plasma density can be increased. In addition, since the sample stage 14 can be included in the plasma generation region, the high-density plasma can increase the energy efficiency even under low pressure, and can process the sample S uniformly at high speed.

Next, in the apparatus shown in FIG. 1, will be described microwave plasma processing apparatus according to the actual 施例 using a reflective plate 32 instead of the reflector 31. A reflector 32 made of Al is provided on the outer periphery of the sample table 14, and the upper surface of the sample table 14 and the upper surface of the reflector 32 are set at substantially the same level.
As shown in FIG. 2, the reflection plate 32 is formed in a substantially rectangular shape, and the reflection plate 32 is formed with a plurality of exhaust holes 32a.
The diameter of the exhaust hole 32a is set to be equal to or less than the hole diameter that forms the non-propagating mode according to the frequency and mode of the microwave. Further, a hole 14a is opened substantially in the center of the reflector 32 so that the sample table 14 can be inserted.
2 is fixed to a predetermined height of the reaction chamber side wall 12a.

When an etching process is performed on the sample S placed on the sample stage 14 by using the apparatus configured as described above, first, cooling water is circulated through the cooling water passage 11, and exhaust gas is exhausted from the exhaust port 15. Then, the reaction chamber 12 is set to a required degree of vacuum. Next, the reaction chamber 12 is set to a predetermined pressure while supplying gas from the gas supply pipe 16 and exhausting the gas through the exhaust hole 32 a of the reflection plate 32. Next, a microwave is oscillated using the microwave oscillator 23, and the microwave is
The electric field formed below the dielectric line 20 is introduced into the reaction chamber 12 through the microwave introduction window 13. Then, the microwave electric field is confined between the microwave introduction window 13 and the reflection plate 32 by the reflection plate 32, and a high electric field is formed. This electric field stably generates plasma and increases the plasma density, and this plasma is guided to the surface of the sample S to etch the surface of the sample S.

Hereinafter, a description will be given of the results of measurement of the plasma generation state and the ion current density distribution above the sample table 14 using the apparatus according to the embodiment . Reflector 32 is 300m
Exhaust hole 3 formed to m × 300 mm and having a diameter of about 5 mm
What used about 94 2a was used. As a comparative example, a conventional device in which the reflection plate 32 was not provided was used. Other measurement conditions are the same as those of the reference example .

The state of plasma generation is shown in Table 1 above, and the measurement results of the ion current density distribution are shown in FIG.

As is clear from Table 1, in the case of the embodiment , even if the pressure was reduced to 2 mTorr, plasma could be generated stably. As is clear from FIG. 3, in the case of the embodiment , the average ion current density was 18 m.
A / cm ² and plasma could be more uniformly generated.

[0025] As described above, in the microwave plasma processing apparatus according to the embodiment, the locations facing the microwave introduction window 13 of the sample stage 14 periphery, holes diameter or under which form non-propagating mode (approximately 5mm ), The reflector 32 for confining the microwave electric field between the microwave introduction window 13 and the microwave electric field is disposed, so that the gas can be exhausted through the exhaust hole 32a, The microwave electric field can be reliably confined between the microwave introduction window 13 and the reflector 32, and the plasma generation region can be narrowed, so that the electric field intensity can be increased and the plasma can be generated even under a low pressure. Can be generated uniformly and stably, and the plasma density can be increased. In addition, since the sample stage 14 can be included in the plasma generation region, high-density plasma
Even under a low pressure, the energy efficiency can be increased, and the sample S can be processed at high speed and uniformly.

In the above embodiment, the case where the microwave plasma processing apparatus is applied to the etching processing has been described. However, the microwave plasma processing apparatus can be used as an ashing apparatus or a thin film forming processing apparatus.

[0027]

As described above in detail, in the microwave plasma processing apparatus according to the present invention, a gas outlet having a diameter smaller than a hole diameter for forming a non-propagating mode is provided at a position facing the microwave introduction window around the sample stage. Since there is a hole and a reflector for confining the microwave electric field between the microwave introduction window and the microwave introduction window is provided, gas can be discharged through the exhaust hole, and the microwave electric field is reduced. Since it is possible to reliably confine the space between the microwave introduction window and the reflector and narrow the plasma generation region, the electric field intensity can be increased, and the plasma can be made uniform and stable even under a low pressure. And the plasma density can be increased. In addition, since the sample stage can be included in the plasma generation region, the high-density plasma can increase the energy efficiency even under low pressure, and can process the sample at high speed and uniformly.

[Brief description of the drawings]

1 (a) is a schematic sectional view showing a reference example of a microwave plasma processing apparatus according to the present invention, (b) the ginseng
It is the top view which showed the reflection plate concerning the example typically.

FIG. 2 is a plan view schematically showing a reflection plate according to an example .

FIG. 3 is a curve diagram showing an ion current density distribution in a reference example , an example, and a comparative example.

FIG. 4 is a cross-sectional view schematically showing a conventional microwave plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Reactor 13 Microwave introduction window 14 Sample stand 20 Dielectric line 22 Waveguide 23 Microwave oscillator 31 Reflector 31a Exhaust port

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shuta Kanayama 4-33, Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd.

Claims (1)

(57) [Claims] 1. A reactor having a microwave oscillator, a waveguide for transmitting microwaves, a dielectric line connected to the waveguide, and a microwave introduction window disposed opposite to the dielectric line. And a sample table provided independently in the reactor, wherein a hole diameter for forming a non-propagating mode is formed at a position facing the microwave introduction window around the sample table. A microwave plasma processing apparatus having the following exhaust holes, and further including a reflector for confining a microwave electric field between the microwave introduction window and the microwave introduction window.