JPH10241899A - Plasma treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treatment device with high plasma density to form uniform and wide plasma which gives less plasma damage to a material to be treated. SOLUTION: A plasma treatment device has plural plane electrodes 2a, 2b arranged at spaces to be extended from a pair of electrode bases opposing each other in a vacuum container 1 to electrode bases 2A, 2B alternately opposing each other and a means 3 to apply a magnetic field to the direction of crossing an electric field arranged in parallel to the plane electrodes 2a, 2b. AC power supplies 6, 7 are connected to a pair of electrode bases 2A, 2B, respectively, to apply AC power with different phases to the plane electrodes 2a, 2b neighboring each other, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a plasma processing apparatus. More specifically, the present invention relates to a plasma processing apparatus which has a high plasma density, can form a uniform and large-area plasma, and has little plasma damage to an object to be processed.

[0002]

2. Description of the Related Art In a conventional capacitor-type plasma processing apparatus, there is a problem that an object to be processed, for example, a semiconductor element formed on a semiconductor wafer is electrically damaged, and a processing object mounted on an electrode plate. There is a problem in that the plasma processing varies depending on the arrangement of the body and the like, and a plasma CVD film or plasma etching with good quality and little variation cannot be performed.

In Japanese Patent Publication No. 61-6536, the above-mentioned 2
As an amorphous thin film forming apparatus that solves the two problems, a reaction gas supply port is provided on the object to supply a uniform plasma-excited reaction gas to the object, and below the reaction gas supply port If necessary, a capacitor-type electrode plate that excites the reaction gas with plasma is installed with a gas discrete acting body that evenly distributes and diffuses the reaction gas, and the object to be processed is arranged under this electrode. There is disclosed a capacitor type plasma processing apparatus that performs a plasma process using an excited reaction gas.

[0004] In particular, this capacitor-type electrode plate is composed of a plurality of electrode plates, and is characterized in that electrode plates to which high-frequency power is applied and electrode plates to be grounded are alternately arranged. It is. As such a capacitor-type electrode plate, a type combining a flat plate and a type combining a cylindrical shape are illustrated in the above publication.

[0005] However, the present inventor has disclosed a technique disclosed in
It has been found that the device described in Japanese Patent No. 6536 has problems in the following points. (1) Since electric power is applied from a single high-frequency power supply to adjacent and opposed electrode plates, it was difficult to obtain a high plasma density. (2) Since a plurality of electrode plates, in which electrode plates to which high-frequency power is applied and electrode plates to be grounded are alternately arranged, are used, a plasma dense / dense region is generated between the electrodes. Since the uniformity of the plasma is reduced due to the influence of the sparse / dense region, there is a problem that it is difficult to form a uniform thin film or etch over a large area. (3) Since all the electrode plates are connected by insulating rods, there is a problem that a film is deposited on the rods and an electric short circuit occurs.

[0006]

According to the present invention, the influence of the flow of the reaction gas is small, the plasma generated between the electrodes does not have a clear sparse / dense region, and an electric short circuit occurs in the electrode plate. It is another object of the present invention to provide a plasma processing apparatus. As a result, a uniform plasma having a high plasma density and a large area can be formed, and a plasma processing apparatus with less plasma damage to an object to be processed can be obtained.

[0007]

According to the present invention, a plurality of plate-like electrode members extending from each of a pair of electrode members facing each other in a vacuum vessel to alternately facing electrode members are arranged in parallel at a predetermined interval. Means for applying a magnetic field in a direction intersecting an electric field formed in a direction in which the plurality of plate-shaped electrode bodies are arranged, and applying AC power having a different phase to each of the adjacent plate-shaped electrode bodies. By connecting the AC power supply to each of the pair of electrode bodies, a plasma processing apparatus capable of realizing uniform and high plasma density can be obtained.

Hereinafter, the operation of the present invention will be described in detail. (1) Since alternating-current power having different phases is applied to the plate-like electrode members arranged at adjacent positions, plasma can be generated between the plate-like electrode members by AC discharge.

(2) The charged particles in the plasma obtain an initial velocity by the Coulomb force given by the discharge electric field. further,
The Lorentz force acts on the charged particles in the plasma by the action of the magnetic field in the direction orthogonal to the electric field for discharge, causing so-called E × B drift motion on the plane orthogonal to the electric field and the magnetic field.

(3) The distance that the charged particles fly in space without colliding with the electrodes is extended by the E × B drift motion, so that the probability of collision with neutral particles in space to ionize the neutral particles is high. To increase.

As a result, the plasma density in the space increases. The charged particles move right or left due to the E × B drift motion, but the direction of the E × B drift is opposite between the opposed plate-shaped electrode bodies, so that the bias of the density due to the E × B drift is reduced as a whole. Is done.

[0012] The generated plasma can increase the length and the number of the plate-shaped electrode bodies as much as possible with respect to the object to be processed such as a glass substrate provided at a position opposed to the plate-shaped electrode body. High-density plasma having an area can be generated with good uniformity.

Further, in the present invention, since the means for applying the magnetic field is a coil, it can be easily installed not only outside the plasma processing apparatus but also inside the plasma processing apparatus, and a low-cost system can be constructed.

Further, in the present invention, since the means for applying the magnetic field comprises a structure in which the side surface of the flat magnetic body is surrounded by a coil, a high magnetic flux density and a uniform magnetic field can be formed. As a result, it is possible to uniformly extract the plasma generated by the flat electrode body into a space opposite to the means for applying a magnetic field across the flat electrode body. In addition, since the magnetic permeability of the magnetic material is about 10 ⁴ times that of vacuum, the introduction of the magnetic material into the coil makes it possible to form a strong magnetic field even with a small current flowing through the coil.

Still further, according to the present invention, since the plate-like electrode bodies to which AC power having the same phase is applied are connected at one end, the plate-like electrode bodies are arranged adjacent to and opposed to each other, and different phases are applied. The bodies can be reliably separated by a space. As a result, the problem that the plate-shaped electrode bodies to which different phases are applied are electrically short-circuited can be solved.

According to the present invention, along the direction of the magnetic field formed by the means for applying the magnetic field, outside the flat electrode body,
Since the magnetic body is arranged, the magnetic field generated by the means for applying the magnetic field can be confined inside the magnetic body arranged outside the flat electrode body. As a result, the utilization efficiency of the plasma generated inside the plasma processing apparatus is improved.
Further, since the magnetic field generated by the means for applying a magnetic field does not leak out of the plasma processing apparatus, it is possible to avoid affecting electronic devices provided outside the plasma processing apparatus.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A plasma processing apparatus according to the present invention includes, for example, those shown in FIGS.

FIG. 1 shows an example of a plasma processing apparatus.
It is the typical sectional view seen from the front. The plasma processing apparatus shown in FIG. 1 uses a coil disposed outside a flat electrode body as a means for applying a magnetic field. FIG. 2 shows FIG.
3 is a schematic cross-sectional view taken along line AA ′ of FIG.

FIG. 3 shows another example of the plasma processing apparatus, and is a schematic sectional view seen from the front. In the plasma processing apparatus shown in FIG. 3, a structure in which a side surface of a flat magnetic material is surrounded by a coil is used as a means for applying a magnetic field, and a flat electrode is formed along the direction of the magnetic field formed by the means for applying a magnetic field. This is a case where a magnetic body is arranged outside the body. FIG.
FIG. 4 is a schematic sectional view taken along the line BB ′ of FIG. 3.

FIG. 5 is a perspective view of the electrode base and the plate-like electrode shown in FIG. 1 or FIG. FIG. 6 is a schematic plan view of the electrode base body and the plate-like electrode body of FIG. 5 as viewed from above the device of FIG. 1 or FIG. FIG. 7 is a schematic diagram for explaining the density of the plasma density generated between the flat electrode bodies.

1 to 7, reference numeral 1 denotes a vacuum vessel, 1 '
Is a side wall portion of the vacuum vessel 1, 2A and 2B are a pair of electrode bases facing each other in the vacuum vessel 1, 2a and 2b are respectively extended from the pair of electrode bases 2A and 2B toward the opposing electrode bases, and A plurality of plate-shaped electrode bodies arranged in parallel at intervals are means for applying a magnetic field in a direction intersecting an electric field formed in the direction in which the plurality of plate-shaped electrode bodies are arranged in parallel. The magnetic material, 5 is a coil arranged outside the magnetic material 4, 6 and 7 are the adjacent plate-shaped electrode bodies 2a and 2
b, an AC power supply connected to each of the pair of electrode bases 2A and 2B so as to apply AC power having a different phase to each of the electrodes b, 8 to be processed, 9 to be a susceptor for mounting the processed object 8, Reference numeral 10 denotes an AC power supply for applying AC power to the target object 8 via the susceptor 9, reference numeral 11 denotes a reactant gas introducing unit, reference numeral 12 denotes a shower head, reference numeral 13 denotes an exhaust unit,
Reference numerals 5 and 16 denote insulators, and reference numeral 17 denotes a magnetic body disposed outside the plate-like electrode bodies 2a and 2b along the direction of the magnetic field formed by the means 3 for applying a magnetic field.

In the plasma processing apparatus (FIG. 1 or FIG. 3) according to the present invention, a flat plate extending from each of a pair of electrode bases 2A and 2B to an oppositely facing electrode base is used as a flat electrode for generating glow discharge plasma. Electrode body 2a
And 2b are arranged side by side at predetermined intervals in total of seven (Fig. 5).
What was done was used. Then, the adjacent plate-like electrode body 2a
AC power supplies 6 and 7 were connected to the pair of electrode bases 2A and 2B, respectively, so that AC powers having different phases were applied to the electrodes 2 and 2b (FIG. 2 or FIG. 4). Further, a magnetic field was generated using the means 3 for applying a magnetic field in a direction orthogonal to the electric field for discharge generated between the adjacent plate-like electrode bodies 2a and 2b. At this time, the plate-shaped electrode bodies 2a and 2b to which AC power having the same phase is applied are connected to the pair of electrode bases 2A and 2B at one end, respectively, and insulators 15 and 16 are provided between the electrode bodies 2A and 2B. (FIGS. 5 and 6).

In the plasma processing apparatus shown in FIG. 1, a means 3 for applying a magnetic field in a direction intersecting an electric field formed in a direction in which a plurality of plate-shaped electrode bodies are arranged is disposed outside the plate-shaped electrode body. This is a case where a coil is used. The direction of the magnetic field can be controlled by the direction of the current flowing through the coil, and the strength of the magnetic field can be controlled by the amount of current flowing through the coil. When only a coil is used as the means 3 for applying a magnetic field as described above, it can be easily installed not only outside the plasma processing apparatus but also inside the plasma processing apparatus, and an inexpensive system can be obtained.

On the other hand, in the plasma processing apparatus shown in FIG. 3, as means 3 for applying a magnetic field in a direction intersecting an electric field formed in a direction in which a plurality of plate-shaped electrode bodies are arranged in parallel, a coil 5 are used, and are arranged vertically so as to sandwich the electrode base bodies 2A and 2B and the plate-shaped electrode bodies 2a and 2b. Further, a magnetic body 17 was provided outside the plate electrode along the direction of the magnetic field formed by the means for applying a magnetic field. As a result, the plasma processing apparatus of FIG. 3 has a higher magnetic flux density than that of the apparatus of FIG. 1 and can form a uniform magnetic field, and the magnetic field generated by the magnetic field applying means 3 is applied to the plate-like electrode bodies 2a and 2b. Can be confined inside the magnetic body disposed outside the. In the plasma processing apparatus shown in FIG. 3, as a means 3 for applying a magnetic field in a direction perpendicular to the electric field formed by the plate-like electrode bodies 2a and 2b, a means in which a coil 5 is wound around a side surface of a magnetic body 4 is used. Although they are arranged vertically so as to sandwich the plate electrode, only one of them may be arranged.

A gas used to generate glow discharge plasma is supplied from the upper portion of the vacuum vessel 1 by a reaction gas introducing means 11. The gas introduced into the vacuum vessel 1 is supplied to a plurality of plate-like electrode bodies 2a and 2b provided in a fence shape via a shower head 12 (FIG. 1 or FIG. 3).

The susceptor 9 on which the object 8 is placed is connected to an AC power supply 10 (frequency: several hundred kHz to several tens MHz) for applying AC power to the object 8 via the susceptor 9. . As a result, ions generated in the plate-like electrode bodies 2a and 2b can be drawn in the direction of the object 8 to be processed.

In the plasma processing apparatus according to the present invention, the charged particles in the plasma obtain the initial velocity by the Coulomb force given by the discharge electric field. Furthermore, the Lorentz force acts by the action of the magnetic field in the direction crossing the electric field for discharge, causing so-called E × B drift motion on a plane perpendicular to the electric field and the magnetic field. This E × B drift motion increases the distance that the charged particles fly in space without colliding with the electrodes, thereby increasing the probability of colliding with neutral particles in space and ionizing the neutral particles. As a result, the plasma density in the space increases. The charged particles move right or left due to the E × B drift motion, but the direction of the E × B drift is opposite between the opposed plate-shaped electrode bodies, so that the bias of the density due to the E × B drift is reduced as a whole. (FIG. 7).

Since the length and number of the above-mentioned plate-like electrode bodies 2a and 2b can be increased arbitrarily, a large-area high-density plasma can be generated with high uniformity by the above-described operation.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to one embodiment of the apparatus shown in FIGS.

The plasma processing apparatus according to the present embodiment has a flat electrode body 2 a for generating a glow discharge in the reaction vessel 1.
2b was arranged in a fence shape. A flat and substantially rectangular magnetic body 4 is provided outside the reaction vessel 1 so as to sandwich the fence-shaped plate-like electrode bodies 2a and 2b, and a coil 5 is wound around the magnetic body 4. The coil 5 was connected to a DC power supply (not shown). Aluminum coated with alumite was used as a material of the plate-like electrode bodies 2a and 2b.

Electric power was supplied from the high-frequency power supplies 6 and 7 to the plate-like electrode bodies 2a and 2b via the electrode bases 2A and 2B, respectively. In this example, the high-frequency power supplies 6 and 7 used were those having a frequency of 13.56 MHz. However, the phase of the electric power applied to the flat electrode body 2a and the flat electrode body 2b is 1
Connections were made to differ by 80 degrees.

The reaction gas introducing means 11 supplies a gas such as hydrogen, argon or xenon into the reaction vessel 1. A vacuum pump 13 was used as means 13 for exhausting the inside of the reaction vessel 1.

After the inside of the reaction vessel 1 is evacuated by driving the vacuum pump 13, argon gas is introduced into the reaction vessel 1 using the reaction gas introduction means 11, and the pressure in the reaction vessel 1 is reduced to It was kept at 10 mTorr. By the way, the pressure inside the reaction vessel 1 may be any pressure as long as a glow discharge is generated, but is preferably set in a range of 0.01 Torr to 2 Torr.

In order to generate a glow discharge between the plate-like electrode body 2a and the plate-like electrode body 2b, the high-frequency power sources 6, 7
Was applied. In this example, a 13.56 MHz high frequency power supply is used. However, a higher frequency power supply may be used, or a low frequency power supply may be used.

The magnetic material 4 is made of Fe (iron).
DC power supply (not shown) connected to coil 5 surrounding the periphery of
The current flowed from. Due to the influence of the magnetic body 4, a magnetic field that is uniform and about 10,000 times stronger than that in the case of vacuum can be generated inside the coil 5. In this manner, a magnetic field B orthogonal to the electric field E generated between the fence-shaped plate-like electrode bodies 2a and 2b was generated. The intensity of the magnetic field at this time could be changed up to 0.5T by adjusting the current value of the coil.

Charged particles such as argon ions and electrons cause a so-called E × B drift motion due to the Coulomb force F1 = qE due to the electric field E and the Lorentz force F2 = q (v × B) due to the action of the magnetic field B. It moves along the electrode body (FIG. 5). This movement increases the probability of ionization due to collision between charged particles and neutral particles, so that the density of plasma generated between the plate-like electrode body 2a and the plate-like electrode body 2b can be increased.

The charged particles move along the plate-shaped electrode body due to the E × B drift, but are adjacent (facing).
Since the moving direction of the E × B drift is opposite between the plate-shaped electrode bodies, the uniformity of the plasma density is maintained macroscopically.

Also, due to the effect of the magnetic body 4, the magnetic field becomes uniform over almost the entire area within the coil, and the magnetic field does not cause the plasma density to be non-uniform.
× 10 ¹² / cm ³ ). When the means 3 for applying a magnetic field consisting of the magnetic material 4 and the coil 5 was not used, the maximum plasma density was up to 2.4 × 10 ¹⁰ / cm ³ . Therefore, it was found that the magnetic material 4 caused a remarkable increase in plasma density. As a result, the flat electrode body 2
Plasma generated in the plate-like electrode bodies 2a and 2b can be uniformly drawn and supplied to the processing target 8 in the space opposite to the means 3 for applying a magnetic field across the electrodes a and 2b.

Further, by applying AC power to the object 8 through the susceptor 9, the plate-like electrode members 2a, 2a
The amount of ions generated in b can be controlled in the direction of the object 8 to be processed. That is, a space having a lower potential than the plasma potential of the plasma generated in the plate-like electrode bodies 2a, 2b is set in the plate-like electrode bodies 2a, 2b.
b could be formed outside the internal space. as a result,
Since the ion energy incident on the object 8 from the plasma can be controlled, plasma damage to the object 8 can be reduced while obtaining an ion assist effect on the object 8. As a result, a high-quality amorphous silicon film or the like can be formed at a low temperature.

In this example, the plate-like electrode bodies 2a and 2b each having a length of 30 cm and a width of 3 cm (a total of seven) were arranged at intervals of 5 cm to form a fence. Almost uniform plasma could be generated over the entire area of 30 cm square. The plate electrodes of the plasma processing apparatus shown in this example can be expanded by increasing the number thereof, and the expansion of the magnetic field is easy, so that uniform and high-density plasma can be generated over a larger area.

[0041]

As described above, according to the plasma processing apparatus of the present invention, a plasma having a high plasma density, a uniform and large-area plasma can be formed, and the plasma to be processed is less damaged. Can be processed.

[Brief description of the drawings]

FIG. 1 is an example of a plasma processing apparatus according to the present invention,
It is the typical sectional view seen from the front.

FIG. 2 is a schematic cross-sectional view taken along the line A-A 'of FIG.

FIG. 3 is another example of the plasma processing apparatus according to the present invention, and is a schematic cross-sectional view as viewed from the front.

FIG. 4 is a schematic cross-sectional view taken along the line B-B 'of FIG.

FIG. 5 is a perspective view of the electrode base and the plate-like electrode shown in FIG. 1 or FIG. 3;

6 is a schematic plan view of the electrode base body and the plate-like electrode body of FIG. 5 as viewed from above the device of FIG. 1 or FIG. 3;

FIG. 7 is a schematic diagram illustrating the density of a plasma density generated between plate electrode bodies.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container, 1 'Side wall part of vacuum container 1, 2A, 2B electrode base material, 2a, 2b plate electrode body, 3 Means for applying a magnetic field, 4, 17 magnetic material, 5 coil, 6, 7, 10 AC power supply, Reference Signs List 8 to-be-processed object, 9 susceptor, 11 reaction gas introduction means, 12 shower head, 13 exhaust means, 14, 15, 16 insulator.

Claims (4)

[Claims] 1. A plurality of plate-like electrode bodies extending from a pair of electrode bases facing each other in a vacuum vessel to alternately facing electrode bases at predetermined intervals, and the plurality of plate-like electrode bodies are arranged in parallel. Means for applying a magnetic field in a direction intersecting an electric field formed in the juxtaposed direction, wherein the AC power supply applies the AC power having a different phase to each of the adjacent plate-shaped electrode bodies. A plasma processing apparatus connected to each of the mother bodies. 2. The plasma processing apparatus according to claim 1, wherein the means for applying the magnetic field is a coil. 3. The plasma processing apparatus according to claim 1, wherein the means for applying the magnetic field has a structure in which a side surface of a flat magnetic body is surrounded by a coil. 4. A magnetic body according to claim 1, wherein a magnetic body is arranged outside the plate-shaped electrode body along a direction of the magnetic field formed by the means for applying the magnetic field. The plasma processing apparatus as described in the above.