JPH0463275A - Microwave plasma device - Google Patents

Abstract

PURPOSE:To efficiently produce plasma in a plasma chamber by providing a main body coil around the plasma producing chamber, a sample chamber coil around a sample chamber and an expanded coil close to the connection between the plasma producing chamber and sample chamber and generating a magnetic field with the polarity opposite to those of the expanded coil and main body coil in the expanded coil. CONSTITUTION:A main body coil 30 is arranged almost concentrically with a plasma producing chamber 11 around the plasma producing chamber 11 and a waveguide 14, and the main body coil 30 is formed with three coils 30a, 30b and 30c through which a current is separately passed. An expanded coil 31 is arranged almost concentrically with a sample chamber 17 in the sample chamber 17 close to the connection between the plasma producing chamber 11 at the lower part of the main body coil 30 and the sample chamber 17, and a magnetic field with the polarity opposite to those of the main body coil 30 and sample chamber coil 32 is generated in the expanded coil 31. The sample chamber coil 32 is arranged almost concentrically with the sample chamber 17 around the sample chamber 17 below the expanded coil 31, and a mirror field generating coil 33 is furnished below a sample holder 19.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave plasma device, and more specifically, mainly to a semiconductor manufacturing process.
chemical vapor deposition
The present invention relates to a microwave plasma device used as an etching device, etching device, etc.

The method of generating plasma by excitation of electron cyclotron resonance (hereinafter referred to as ECR) can generate plasma with a high degree of ionization at low gas pressure, allows a wide selection of ion energies, and can generate large ions. It has advantages such as being able to carry a current and having excellent directionality and uniformity of ion flow. For this reason, active research and development is progressing on it as an indispensable device for processes such as thin film formation and etching in the manufacture of high-frequency semiconductor devices and the like.

FIG. 3 is a cross-sectional view schematically showing an etching device as an example of a conventional microwave plasma device.
1 indicates a plasma generation chamber. Plasma generation chamber 11
is partitioned by a peripheral wall 11b having a cylindrical shape in which a cooling water channel 11a is formed, an upper wall 11c, and a lower wall 11d, and a microwave inlet 12 is provided approximately at the center of the upper wall 11c. is formed. The microwave introduction port 12 has a microwave introduction window 1 disposed above it.
3, and the lower end of a waveguide 14 is connected to the microwave introduction port 12 via this microwave introduction window 13. The upper end of the waveguide 14 is connected to a microwave oscillator (not shown), and the microwave generated by the microwave oscillator is transmitted to the waveguide 14 and the microwave introduction window 13.
It is designed to be guided into the plasma generation chamber 11 through. Further, a gas supply pipe 15 is connected to the upper wall 11c, and an excitation coil 18 is arranged around the lower end of the plasma generation chamber 11 and the waveguide 14, approximately concentrically with the plasma generation chamber 11. has been done.

On the other hand, a plasma extraction window 16 is formed in the lower wall lid of the plasma generation chamber 11, and a sample chamber 17 is arranged below the plasma extraction window 16 and communicates with the plasma generation chamber 11 through the plasma extraction window 16. ing.

A sample stage 19 that holds the sample 8 with an electrostatic chuck or the like is provided at a location facing the plasma draw-out window 16 of the sample chamber 17.
An exhaust port 20 connected to an exhaust device (not shown) is formed in the lower wall of the sample chamber 17.

When etching the sample S using the microwave plasma apparatus configured as described above, first set the plasma generation chamber 11 and the sample chamber 17 to the required degree of vacuum, and then After a required gas is supplied through the gas supply pipe 15, microwaves are introduced into the plasma generation chamber 11 through the waveguide 14 while forming a magnetic field with the excitation coil 18. Then, the gas is resonantly excited using the plasma generation chamber 11 as a cavity resonator, and plasma is generated within the plasma generation chamber 11. The generated plasma is projected around the sample S in the sample chamber 17 by a divergent magnetic field formed by the excitation coil 15 and whose magnetic flux density decreases toward the sample chamber 17, thereby etching the surface of the sample S. will be applied.

Furthermore, in addition to the above-mentioned apparatus, a plasma processing apparatus shown in FIG.
4-81213). That is, in FIG. 4, the excitation coil 28 is composed of two coils 28a and 28b that can be individually energized, and the outer circumferential surface, upper surface, and upper inner circumferential surface of the excitation coil 28 are each covered with a magnetic material 29a.
, 29b and 29c. The lower end of the magnetic body 29c is bent inward near the lower end of the waveguide 14 to form an edge 29d, and the coil 28a and 2
A magnetic body 29e is also interposed between the magnetic body 8b and the magnetic body 29e.

In this device, magnetic bodies 29a, 29b, 29c,
29d and 29e constitute a magnetic path, and the coil 28a
, 28b, a magnetic field distribution as shown in FIG. 5 is formed. Due to this magnetic field configuration, a large region (formed) that satisfies the ECR conditions is formed in the plasma generation chamber 11, so that plasma generation is performed efficiently, and the plasma flow toward the microwave introduction port 12 is suppressed, so that the microwave can be introduced. Thermal load on the window 13 is suppressed.

However, in any of the above-mentioned microwave plasma devices, the magnetic field formed by the excitation coil 18, 28 is a divergent magnetic field whose magnetic flux density decreases as it moves toward the sample chamber 17 side. Magnetic field lines are obliquely incident on the surface of sample S. Since the charged particles move along the magnetic field lines, ions in the plasma that contribute to etching and film formation are obliquely incident on sample S, resulting in an oblique etched shape. However, there was a problem that the film was not formed uniformly.

Furthermore, in the monotonically divergent magnetic field formed in the plasma processing apparatus shown in FIG. 3, the ratio of the magnetic flux tube diameter in the plasma generation chamber 11 along the same magnetic field line to the magnetic flux tube diameter near the sample S is large; Therefore, only plasma from a narrow area within the plasma generation chamber 11 is drawn out and used, resulting in a problem of poor efficiency. Furthermore, in a magnetic field that monotonically changes within the plasma generation chamber 11, the magnetic field strength region suitable for generating plasma by ECR excitation, for example, is only distributed in a planar manner, resulting in poor plasma generation efficiency.

The present invention was made in view of the above-mentioned problems, and it is possible to efficiently generate plasma, make the generated plasma have a large diameter, and obtain an ion flow with improved directionality. The object of the present invention is to provide a microwave plasma apparatus that can perform etching or film formation of an excellent shape.

In order to achieve the above-mentioned object, a microwave plasma device according to the present invention is provided with a plasma generation chamber that generates plasma by electron cyclotron resonance excitation, and a sample stage on which a sample is placed. A microwave plasma apparatus comprising a sample chamber into which plasma generated by the sample is introduced to process the sample, a main body coil at least at the outer circumference of the plasma generation chamber, a sample chamber coil at the outer circumference of the sample chamber,
Enlargement coils are disposed near the connecting portions of the plasma generation chamber and the sample chamber, and the enlargement coils are configured to form a magnetic field of opposite polarity to the main body coil and the sample chamber coil. Further, in any of the above devices, a mirror magnetic field forming coil is disposed below the sample stage, and further in any of the above devices, a mirror magnetic field is formed near the microwave introduction window. It is characterized by being configured as follows.

Furthermore, the above three devices are characterized in that a magnetic material is disposed on the outer periphery of the main body coil, expansion coil, and sample chamber coil, except in the direction facing the plasma generation chamber and the sample chamber.

In many cases, the plasma generation efficiency and distribution are determined by the magnetic field distribution, and in plasma generation methods using ECR, the ECR
When lit, a strong plasma is generated.

According to the above-described apparatus, a main body coil is provided at least on the outer periphery of the plasma generation chamber, a sample chamber coil is provided on the outer periphery of the sample chamber, and an enlargement coil is provided near the connection between the plasma generation chamber and the sample chamber. The expansion coil is configured to form a magnetic field of opposite polarity to the main body coil and the sample chamber coil, so that direct current is passed through each of the main body coil, the expansion coil, and the sample chamber coil. When flowing, a downward magnetic field is uniformly formed by the main body coil over almost the entire area of the plasma generation chamber, and this magnetic field is expanded around the plasma extraction window by the upward magnetic field formed by the expansion coil. The magnetic field from the enlarged plasma extraction window to the sample position expands in the shape of a via dal at its center, but is pushed in the direction of the central axis of the sample chamber by the sample chamber coil and corrected. A group of magnetic lines of force are formed that are perpendicularly incident on the magnetic field.

Therefore, when microwaves are introduced into the plasma generation chamber, plasma is efficiently generated in a wide area within the plasma generation chamber, and most of the generated plasma is drawn out to the sample chamber side by the magnetic field formed by the main body coil. Then, the plasma diameter is expanded along the group of magnetic lines of force expanded by the expansion coil. Thereafter, the plasma is again projected onto the sample along parallel lines of magnetic force, and the ions in the plasma are incident approximately perpendicularly onto the sample.

Furthermore, in the above-described apparatus, when a mirror magnetic field forming coil is disposed below the sample stand, the magnetic field expanded by the magnifying coil is reduced by the mirror magnetic field formed below the sample stand. . Therefore, it becomes easy to form a group of lines of magnetic force that are parallel to the sample and incident perpendicularly to the sample.

Furthermore, in any of the above devices, if a mirror magnetic field is formed near the microwave introduction window, the mirror magnetic field suppresses charged particles in the plasma from moving toward the micro introduction window. This reduces the heat load on the microwave introduction window.

In these three devices, if a magnetic material is disposed on the outer periphery of the main body coil, expansion coil, and sample chamber coil except in the direction facing the plasma generation chamber and sample chamber, the magnetic field will be concentrated and the magnetic path can be used effectively, so a magnetic field can be effectively created with less power.

! Embodiments of the microwave plasma apparatus according to the present invention will be described below with reference to the drawings. Note that components having the same functions as those of the conventional example are given the same reference numerals.

FIG. 1 is a cross-sectional view schematically showing an embodiment of a plasma processing apparatus according to the present invention, and reference numeral 11 in the figure indicates a plasma generation chamber formed in a substantially cylindrical shape. At approximately the center of the upper part of the plasma generation chamber 11, there is a microwave inlet 12.
is formed, and the microwave introduction port 12 is sealed by a microwave introduction window 13 disposed above the microwave introduction port 12.

The microwave introduction port 12 has this microwave introduction window 13.
The lower end of the waveguide 14 is connected via the waveguide 14, and the upper end of the waveguide 14 is connected to a microwave oscillator (not shown).

Microwaves generated by the microwave oscillator are guided into the plasma generation chamber 11 via the waveguide 14 and the microwave introduction window 13.

At the bottom of the plasma generation chamber 11, there is a plasma extraction window 1.
A sample chamber 17 is provided below the plasma extraction window 16 and communicates with the plasma generation chamber 11 through the plasma extraction window 16.

Further, a sample stage 19 for holding the sample S using an electrostatic chuck or the like is provided at a location facing the plasma extraction window 16 of the sample chamber 17.

On the other hand, a main body coil 30 is arranged around the lower end of the plasma generation chamber 11 and the waveguide 14 so as to be substantially concentric with the plasma generation chamber 11.
It is composed of three coils 30a, 30b, and 30c through which current can be passed individually. In the sample chamber 17 near the connecting part between the plasma generation chamber 11 and the sample chamber 17 below this main body coil 30, an enlarged coil 3 is provided approximately concentrically with the sample chamber 17.
1 is arranged, and the enlarged coil 31 is connected to the main body coil 30.
It is also configured to form a magnetic field of opposite polarity to that of the sample chamber coil 32, which will be described later. Further, a sample chamber coil 32 is disposed approximately concentrically with the sample chamber 17 on the outer periphery of the sample chamber 17 below the magnifying coil 31, and a mirror magnetic field forming coil 33 is disposed below the sample stage 19. .

In the microwave plasma apparatus configured in this way, after placing the sample S on the sample stage 19, the inside of the plasma generation chamber 11 and the sample chamber 17 are set to the required degree of vacuum, and then the inside of the plasma generation chamber 11 is The required gas is supplied through a gas supply pipe (not shown). Then, the ampere turns to each coil 30a, 30b, 30c of the main body coil 30 are adjusted to pass a direct current through each coil 30a, 30b, 30c, and the expansion coil 31, sample chamber coil 32, and mirror magnetic field forming coil A direct current is also passed through each of 33. Then, as shown in the first section, a downward magnetic field is uniformly formed by the main body coil 30 over almost the entire area of the plasma generation chamber 11, and this magnetic field is caused by the upward magnetic field formed by the expansion coil 31 to extend through the plasma extraction window. It is expanded around 16. The expanded magnetic field is then reduced by the mirror magnetic field formed by the mirror magnetic field forming coil 33. At this time, the magnetic field from the plasma extraction window 16 to the sample S position expands in the shape of a via dal at its center, but the sample chamber coil 32
In this space, a group of magnetic lines of force are formed which are parallel to each other and incident perpendicularly to the sample S.

At this time, by adjusting the current flowing through the main body coil 30, expansion coil 31, and sample chamber coil 32, a plasma of 875G (by ECR excitation) is placed at a desired position in the space from the plasma generation chamber 11 to the sample S position. A magnetic field strength greater than the magnetic field strength required to generate a magnetic field is formed.

When microwaves are introduced into the plasma generation chamber 11 from the waveguide 14 while forming a magnetic field as described above, gas is resonantly excited using the plasma generation chamber 11 as a cavity resonator, and a wide area within the plasma generation chamber 11 is excited. Plasma is generated efficiently in

Most of the generated plasma is drawn out to the sample chamber 17 side by the magnetic field formed by the main body coil 30, and after the plasma diameter is expanded along the group of magnetic lines of force expanded by the expansion coil 31, it is drawn out again along the group of parallel lines of magnetic force. Sample S
is projected on. As a result, ions in the plasma are incident on the sample S substantially perpendicularly, and the surface of the sample S is etched in an excellent shape.

In the above-mentioned apparatus, a case has been described in which the mirror magnetic field forming coil 33 is disposed below the sample stage 19, but instead of the mirror magnetic field forming coil 33, the sample stage 1
The sample chamber coil 32 may be arranged to extend below the sample chamber 9, and the same effect as described above can be obtained in that case as well.

FIG. 2 is a schematic diagram showing the state of the magnetic field formed in the plasma processing apparatus when a magnetic material 34 made of iron or the like is further disposed around each of the main body coil 30, expansion coil 31, and sample chamber coil 32. It is a diagram. That is, in FIG. 2, magnetic bodies 34a, 34b, and 34 are provided on the outer circumferential surface, upper surface, lower surface, and upper inner circumferential surface of the main body coil 30, respectively.
c and 34d, the lower end of the magnetic body 34c is bent inward near the lower end of the waveguide 14, and the edge 34
e is formed. Also, on the outer circumferential surface of the expansion coil 31, the outer circumferential surface, the upper surface, and the lower surface of the sample chamber coil 32, respectively.
Magnetic bodies 34f, 34g, 34h, and 341 are provided. In this way, a magnetic material 34 made of iron or the like is disposed on the outer periphery of each of the main body coil 30, expansion coil 31, and sample chamber coil 32, except in the direction facing the plasma generation chamber 11 and sample chamber 17. By effectively utilizing the magnetic path formed by the body 34, it is possible to effectively form a magnetic field even with a small amount of electric power, as shown in FIG.

In addition, as another embodiment of the plasma processing apparatus described above, a fourth coil 30 is provided instead of the main body coil 30 in FIG.
As shown in the figure, the coil 2 can generate a larger magnetic field at the outer circumference of the plasma generation chamber 11 than the coil 28b.
8a is arranged, and a magnetic body 29a, a FiFi body 29
e is arranged, and as shown in Fig. 5, the microwave introduction window 1
One example is one configured so that a mirror magnetic field is formed in the vicinity of 3. In this case, the mirror magnetic field suppresses the charged particles in the plasma from moving toward the micro-introduction window 13, so that the heat load on the microwave introduction window 13 can be reduced. Therefore, this device can cope with high microwave power, and can also improve plasma utilization efficiency even with low microwave power.

Although FIG. 4 shows an example in which magnetic bodies 29a, 29b, and 29e are provided, these magnetic bodies 29a, 29b, and 29e may not be provided. However, magnetic bodies 29a, 29b, 29
It is more advantageous in terms of utilization efficiency of magnetic lines of force to arrange the magnetic field lines.

Note that the mirror magnetic field described above can also be formed by controlling the direct current of each coil 30a, 30b, and 30c constituting the main body coil 30 shown in FIG. 1, and passing currents of different strengths. can.

Furthermore, in the above embodiments, the case where the present invention is used in an etching apparatus has been described, but it is also possible to use it in a CVD apparatus or the like, and in this case, a good film can be formed on the surface of the sample S.

As is clear from the above explanation, in the microwave plasma apparatus according to the present invention, at least a main body coil is provided on the outer periphery of the plasma generation chamber, and a sample chamber coil is provided on the outer periphery of the sample chamber. However, an expansion coil is disposed near a connecting portion between the plasma generation chamber and the sample chamber, and the expansion coil is configured to form a magnetic field with a polarity opposite to that of the main body coil and the sample chamber coil. Therefore, plasma can be efficiently generated in a wide area within the plasma generation chamber, and plasma transport efficiency can be improved. In addition, a large-diameter plasma can be obtained, and ions in the plasma can be made substantially perpendicular to the sample.

Therefore, it is possible to perform etching or film formation in an excellent shape, and the same effect can be obtained even on a large diameter sample.

In addition, in the above-mentioned apparatus, when a mirror i-field forming coil is arranged below the sample stage, the magnetic field expanded by the expansion coil can be efficiently reduced by the mirror magnetic field formed below the sample stage. can. Therefore, it is possible to easily form a group of lines of magnetic force that are parallel to the sample and incident perpendicularly to the sample.

Furthermore, in any of the above devices, if a mirror magnetic field is formed near the microwave introduction window, the mirror magnetic field suppresses the charged particles in the plasma from moving toward the micro introduction window. This reduces the heat load on the microwave introduction window.

Furthermore, in the above three devices, if the m-type body is arranged on the outer periphery of the main body coil, expansion coil, and sample chamber coil except in the direction facing the plasma generation chamber and sample chamber, the magnetic field will be concentrated. Since the magnetic path can be used effectively, a magnetic field can be effectively formed with less electric power. Therefore, it is possible to cope with high microwave power, and it is also possible to improve plasma utilization efficiency even at low microwave power.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing an example of a microwave plasma device according to the present invention, and FIG. 2 is a state of the magnetic field in the plasma processing device when a magnetic material is further provided in the device of FIG. 1. FIG. 3 is a cross-sectional view schematically showing an etching device as an example of a conventional microwave plasma device, and FIG. 4 is a schematic diagram showing an etching device as another example of a conventional microwave plasma device. FIG. 5, which is a schematic cross-sectional view, is a graph showing the magnetic field strength distribution in the plasma generation chamber of the apparatus shown in Section 4. Fig. 1 11... Plasma generation chamber 13... Microwave introduction window 17... Sample chamber 19... Sample stage 30...
Main body coils 30a, 30b, 30c...Coil 31...Enlargement coil 32...Sample chamber coil 33...Mirror magnetic field forming coil 34...Magnetic body S...Sample

Claims (4)

[Claims] (1) A microwave plasma device equipped with a plasma generation chamber that generates plasma by electron cyclotron resonance excitation, a sample chamber on which a sample is placed, and a sample chamber into which the generated plasma is introduced and processes the sample. A main body coil is disposed at least on the outer periphery of the plasma generation chamber, a sample chamber coil is disposed on the outer periphery of the sample chamber, and an enlargement coil is disposed near a connecting portion between the plasma generation chamber and the sample chamber, and A microwave plasma apparatus characterized in that the expansion coil is configured to form a magnetic field with a polarity opposite to that of the main body coil and the sample chamber coil. (2) The microwave plasma apparatus according to claim 1, wherein a mirror magnetic field forming coil is disposed below the sample stage. (3) The microwave plasma apparatus according to claim 1 or 2, wherein the microwave plasma apparatus is configured so that a mirror magnetic field is formed near the microwave introduction window. (4) The microwave plasma device according to claim 1, 2 or 3, wherein a magnetic material is disposed on the outer periphery of the main body coil, the expansion coil, and the sample chamber coil, excluding the direction facing the plasma generation chamber and the sample chamber. .