JPH05129094A - Plasma treatment method and device - Google Patents

Abstract

PURPOSE:To perform plasma treatment by which uneveness of plasma due to a magnetic field is eliminated so as to accomplish its uniformity and high efficiency and at the same time charge-up damage of a substrate to be treated is suppressed to a low level. CONSTITUTION:A high frequency power is applied to an upper electrode 4 from a first high frequency power supply 6 and its whole surface orthogonal to a magnetic field is exposed to plasma, and the paths of ions electrons in the plasma which are drifted due to the magnetic field have no trailing ends. Moreover, the high frequency power from a second high frequency power supply 13 is applied to a lower electrode 10 and the energy of the ions incident to a substrate 9 to be treated may be controlled by the lower electrode 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing method and a processing apparatus to which low temperature plasma is applied, and more particularly to a high efficiency plasma processing method and a processing apparatus to which a magnetic field is applied.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to the drawings. FIG. 6 shows a schematic sectional view of a conventional plasma processing apparatus. FIG. 6B is a schematic cross-sectional structure view as seen from the direction of arrow c in FIG. The processing chamber 61 has an exhaust port 62.
A desired gas is introduced from the gas introduction port 63. The substrate 64 to be processed is placed on the lower electrode 65, and the lower electrode 65 is placed on the insulating support base 66.
The lower electrode 65 is connected to a high frequency power supply 67, the processing chamber 61 is grounded, and plasma is generated between the lower electrode 65 and the processing chamber 61. Further, when a magnetic field generator 68 using a permanent magnet or an electromagnet is installed and the S pole and N pole are arranged in the arrangement shown in FIG. 6, ions and electrons in the plasma drift in the direction of arrow 69. This drift increases the plasma density, but lower electrode 6
Since 5 has an end, a bias of plasma is generated in the vicinity 70 of the end of the lower electrode 65 (the end of the drift path). In the conventional plasma processing method, the magnetic field generator 68 is rotated about the center of the lower electrode 65 indicated by the alternate long and short dash line 71 as the rotation axis in order to improve the non-uniformity of the processing due to the bias of the plasma.

[0003]

SUMMARY OF THE INVENTION In the above conventional configuration,
Since there is a termination in the path where ions and electrons drift, the efficiency is poor and processing non-uniformity occurs due to plasma bias. Further, in order to alleviate this, a mechanical device such as rotating the magnetic field generator 68 is required, which causes a failure. In addition, when applied to the manufacturing process of a semiconductor device, charge-up due to bias of plasma often occurs, and the semiconductor device is often damaged.

An object of the present invention is to provide a plasma processing method and a processing apparatus capable of eliminating the bias of plasma due to a magnetic field, performing plasma processing uniformly and highly efficiently and suppressing damage due to charge-up of a substrate to be processed. That is.

[0005]

A plasma processing method according to claim 1, wherein a substrate to be processed is placed on a control plate electrode in a grounded processing chamber, and a flat plate type high frequency applying electrode is arranged to face the substrate to be processed. High frequency power is applied to form a magnetic field parallel to the flat plate surface of the flat plate type high frequency applying electrode.

In the plasma processing method according to the second aspect, the substrate to be processed is installed on the control plate electrode in the grounded processing chamber,
High-frequency power is applied to a cylindrical high-frequency applying electrode arranged so that the central axis is perpendicular to the substrate to be processed, and a cylindrical ground electrode having the same central axis as the high-frequency applying electrode is grounded. A divergent magnetic field is formed from the ground electrode to the substrate to be processed.

According to a third aspect of the plasma processing method, the substrate to be processed is installed on the control plate electrode in the grounded processing chamber,
High-frequency power is applied to a cylindrical high-frequency applying electrode arranged so that the central axis is perpendicular to the substrate to be processed, and a cylindrical ground electrode having the same central axis as the high-frequency applying electrode is grounded. A parallel magnetic field is formed from the ground electrode to the substrate to be processed.

According to a fourth aspect of the present invention, there is provided a plasma processing method, in which a substrate to be processed is installed on a control plate electrode in a grounded processing chamber,
High-frequency power is applied to a cylindrical high-frequency applying electrode arranged so that the central axis is perpendicular to the substrate to be processed, and a cylindrical ground electrode having the same central axis as the high-frequency applying electrode is grounded. A cusp magnetic field is formed between the ground electrode and the substrate to be processed.

According to a fifth aspect of the plasma processing apparatus, a grounded processing chamber, a flat plate type high frequency applying electrode which is arranged facing the substrate to be processed and to which high frequency power is applied, and a high frequency applying electrode via the substrate to be processed. It is provided with a control flat plate electrode which is arranged facing each other and on which a substrate to be processed is placed, and a magnetic field generator which generates a magnetic field parallel to the flat plate surface of the high frequency applying electrode. The plasma processing apparatus according to claim 6, wherein a grounded processing chamber, a cylindrical high-frequency applying electrode to which high-frequency power is applied and arranged so that the central axis is perpendicular to the substrate to be processed, and the high-frequency applying electrode and the center. A cylindrical ground electrode with the same axis, a control plate electrode for setting the substrate to be processed, and a magnetic field in a direction parallel to the central axes of the high-frequency applying electrode and the ground electrode, which are placed near the high-frequency applying electrode and the ground electrode. And a cylindrical electrode side magnetic field generator for generating

A plasma processing apparatus according to a seventh aspect is the plasma processing apparatus according to the sixth aspect, wherein the plasma processing apparatus is disposed in the vicinity of the substrate to be processed and generates a magnetic field in a direction parallel to the central axes of the high frequency applying electrode and the ground electrode. A processing substrate side magnetic field generator is provided.

[0011]

In the plasma processing method and the processing apparatus according to the first and fifth aspects, since the flat plate type high frequency applying electrode is surrounded by the plasma in the direction perpendicular to the magnetic field, the ions and the electrons are applied to the high frequency applying electrode with the direction of the magnetic field as an axis. Turn around. Further, in the plasma processing method and the processing apparatus according to claims 2, 3, 4, 6, and 7, the plasma generated between the cylindrical high-frequency applying electrode and the ground electrode is grounded by the magnetic field to the cylindrical high-frequency applying electrode. Swirl between the electrodes.

Therefore, since the ion or electron drift path is closed without any termination, the ionization efficiency of plasma is extremely high. Therefore, since there is no bias of plasma and the uniformity of plasma processing is high, a mechanism for rotating the magnetic field generator is not necessary. Even when applied to the manufacturing process of a semiconductor device, there is no charge-up due to bias of plasma, and damage to the semiconductor device can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of a plasma processing apparatus according to a first embodiment of the present invention. Note that FIG. 1B is a schematic sectional structure view as seen from the direction of arrow a in FIG.

In FIG. 1, the processing chamber 1 is exhausted from an exhaust port 2 and a desired gas is introduced from a gas introduction port 3.
The upper electrode (plate type high frequency applying electrode) 4 is supported in the processing chamber 1 by an insulating support 5 and is connected to a first high frequency power source 6 to which high frequency power is applied. Further, the processing chamber 1 is grounded, and between the processing chamber 1 and the upper electrode 4,
Generates plasma. The end of the upper electrode 4 is rounded in order to avoid local concentration of the electric field. Further, there is a magnetic field generator 7 composed of a permanent magnet, and as shown in FIG.
When the poles are arranged, a magnetic field in the direction of arrow 8 is applied to the plasma. The substrate 9 to be processed is placed on a lower electrode (flat plate electrode for control) 10, and the lower electrode 10 is installed in the processing chamber 1 by an insulating support 11.

The ions and electrons of the plasma generated in the processing chamber 1 drift in the direction of arrow 12 due to the cathode drop and magnetic field generated by the area ratio of the upper electrode 4 and the processing chamber 1, and swirl around the upper electrode 4. To do. Since the drift trajectories of ions and electrons are closed and have no termination, plasma ionization is promoted, high-density plasma is generated, and the bias of plasma is extremely small.

Although the substrate 9 to be processed is plasma-processed by the high-density plasma thus generated, the lower electrode 1
The obtained effect is different when 0 is grounded and when it is connected to the second high frequency power supply 13 and high frequency power is applied. This will be further described by taking the case of application to plasma etching of a silicon substrate as an example.

For example, chlorine gas of 50 sccm is introduced as an etching gas, and the pressure in the processing chamber 1 is maintained at 10 Pa. A high frequency power of 13.56 MHz, for example, was applied from the first high frequency power supply 6, the power density on the surface of the upper electrode 4 was 0.5 W / cm ² , and the magnetic flux density from the magnetic field generator 7 was 100 Gauss. First, the lower electrode 10
Regarding the etching of the substrate 9 to be processed when the substrate is grounded,
A description will be given with reference to the drawings. 2A and 2B are cross-sectional structural views of the substrate to be processed 9. FIG. 2A shows a state before etching and FIG. 2B shows a state after etching.

The substrate 9 to be processed has a silicon substrate 21.
A silicon dioxide film 22 having a thickness of 10 nm is formed thereon, and a polycrystalline silicon film 23 having a thickness of 400
It is formed with a thickness of m. On top of these laminated structures,
The photoresist 24 having a thickness of 1200 nm forms a desired pattern (FIG. 2A). FIG. 2B shows the result of plasma etching under the above conditions. Since the lower electrode 10 is grounded, the directionality of ions in the plasma is small, and an isotropic etching shape as shown in FIG. 2B is obtained.

Next, the second high frequency power source 1 is applied to the lower electrode 10.
The case where 3 is connected and high frequency power is applied will be described. A high frequency power of, for example, 100 KHz was applied to the lower electrode 10 from the second high frequency power supply 13, and the power density on the surface of the lower electrode 10 was set to 0.3 W / cm ² . As the substrate 9 to be processed, the same structure as that of the above example shown in FIG. 2A was used.
FIG. 3 is a sectional structural view of the substrate 9 to be processed after etching in this case.

A cathode fall potential is generated in the lower electrode 10 by the electric power applied to the lower electrode 10, and the directionality of ions in the plasma is increased, so that an anisotropic etching shape is obtained as shown in FIG. As in this embodiment, the frequency of the second high frequency power source 13 (100 KHz) is the first high frequency power source 6
If the frequency is sufficiently lower than the frequency (13.56 MHz), even if the power applied from the second high-frequency power source 13 to the lower electrode 10 is small, a large cathode drop voltage can be obtained, which is almost independent of plasma generation and is not processed. The directionality of the ions incident on the substrate 9 can be determined.

[Second Embodiment] A second embodiment of the present invention will be described with reference to the drawings. 4 and 5 are schematic sectional views of the plasma processing apparatus according to the second embodiment of the present invention. FIG. 5 is a schematic sectional structural view of the AA cross section shown in FIG. 4 viewed from the direction of arrow b. 4 and 5, the processing chamber 41 is exhausted from the exhaust port 42, and a desired gas is introduced from the gas introduction port 43. The high frequency applying electrode (cylindrical high frequency applying electrode) 44 is an insulating support base 45.
Is supported in the processing chamber 41, is connected to the first high-frequency power source 46, and high-frequency power is applied. Further, the ground electrode 47 is installed so as to concentrically surround the high frequency applying electrode 44, and is grounded to the same potential as the processing chamber 41. A high-frequency applying outer electrode (cylindrical high-frequency applying electrode) 48 is installed between the ground electrode 47 and the processing chamber 41 on a support 45 having an insulating property in a concentric circle surrounding the ground electrode 47. It is connected to the. That is, the high frequency applying electrode 44, the ground electrode 47, the high frequency applying outer electrode 48, and the processing chamber 41 form a plasma generation electrode group 50 in which they are concentrically arranged. Also, each electrode 4
The ends of 4, 47 and 48 are rounded to avoid local concentration of electric field.

Plasma is generated between the electrodes 44 and 48 to which a high frequency is applied, the grounded electrode 47 and the processing chamber 41. Furthermore, there is a first magnetic field generator (cylindrical electrode side magnetic field generator) 49 made of a coil outside the processing chamber 41,
For example, when a magnetic field is applied in the direction of arrow b in FIG. 4, ions and electrons in plasma drift in the direction of arrow 51 in FIG. 5 and swirl in the plasma generating electrode group 50. Since the drift trajectories of ions and electrons are closed and there is no termination, plasma ionization is promoted and high-density plasma is generated.
The bias of plasma is extremely small. The substrate 52 to be processed is placed on the lower electrode (flat plate electrode for control) 53, and the lower electrode 53
Are installed in the processing chamber 41 by an insulating support 54.

When the lower electrode 53 is grounded and a divergent magnetic field is formed from the plasma generating electrode group 50 toward the substrate 52 to be processed, the high-density plasma drifts in the direction of divergence, The processed substrate 52 is reached. In this case, since the substrate 52 to be processed has an extremely low bias voltage, the directionality of the ions is small, and the processing shown in FIG. 2 of the first embodiment can be performed.

Further, since the lower electrode 53 is grounded and the shape or position of the first magnetic field generator 49 made of a coil is changed, a parallel magnetic field is generated from the plasma generating electrode group 50 to the substrate 52 to be processed. When it is formed, the plasma easily enters the substrate 52 to be processed in the vertical direction, and when the pressure in the processing chamber 41 is set to about 0.1 Pa, for example, as shown in FIG. 3 of the first embodiment. Such processing becomes possible. However, in the case of application to plasma etching, if the number of overetches increases, the undercut shape shown in FIG. 2B is processed when the film to be etched is the polycrystalline silicon film 23 as in this embodiment. Sometimes.

The lower electrode 53 is the second high frequency power source 5
5, when high frequency power is applied, for example,
If the frequency of the first high frequency power supply is 13.56 MHz and the frequency of the second high frequency power supply 55 is 100 KHz, the second
Even if the power of the high frequency power source 55 is small, the bias voltage generated in the lower electrode 53 is large, and the energy of the ions incident on the substrate 52 to be etched can be controlled with almost no effect on the generation of plasma.

Further, a second magnetic field generator (magnetic field generator for the substrate to be processed) 5 is provided around the processing chamber 41 near the lower electrode 53.
When 6 (see FIG. 4) is provided and a cusp magnetic field is formed between the first magnetic field generator 49 and the magnetic field generated by the first magnetic field generator 49, the plasma generated in the plasma generating electrode group 50 is circularly mixed with the cusp magnetic field, It becomes uniform plasma and reaches the substrate 52 to be processed. As a result, the substrate 52 to be processed is subjected to uniform plasma processing. Also in this case, the lower electrode 53
If high frequency power is applied from the second high frequency power supply 55 to
It goes without saying that the energy of the incident ions can be controlled.

The plasma processing apparatus of this embodiment is extremely efficient because it can uniformly generate high-density plasma. Further, for example, when applied to a manufacturing process of a semiconductor device, since there is no bias of plasma, high-speed processing is possible while suppressing damage due to charge-up. Although the embodiments of the present invention have been described above, the frequency of the high frequency power supply, the type of power, the type of gas, the number of electrodes arranged concentrically, and the like may be other than those described here.

[0028]

As described above, according to the plasma processing method and the processing apparatus of the present invention, extremely efficient plasma processing can be performed with good uniformity, and the substrate to be processed is less damaged. No extra mechanism is required, and the failure as a device can be reduced. Further, the directionality and energy of the ions incident on the substrate to be processed can be controlled by the voltage applied to the control plate electrode, and for example, in the processing by plasma etching, it becomes easy to etch into various cross-sectional shapes. Further, similar control can be performed depending on how the magnetic field is applied. According to the present invention, various kinds of processing over a wide range as described above can be controlled with extremely high efficiency and damage due to charge-up can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a plasma processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional structural view of a substrate to be processed.

FIG. 3 is a cross-sectional structure diagram of a substrate to be processed.

FIG. 4 is a schematic sectional view of a plasma processing apparatus according to a second embodiment of the present invention.

FIG. 5 is a schematic sectional view of a plasma processing apparatus of a second embodiment of the present invention.

FIG. 6 is a schematic sectional view of a conventional plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 processing chamber 4 upper electrode (plate type high frequency applying electrode) 7 magnetic field generator 9 substrate 10 to be processed lower electrode (plate electrode for control) 41 processing chamber 44 high frequency applying electrode (cylindrical high frequency applying electrode) 47 ground electrode 48 High frequency applying outer electrode (cylindrical high frequency applying electrode) 49 First magnetic field generator (cylindrical electrode side magnetic field generator) 52 Processed substrate 53 Lower electrode (control plate electrode) 56 Second magnetic field generator (target) Processing substrate side magnetic field generator)

Claims (7)

[Claims] 1. A high-frequency applying electrode of a flat plate type, wherein a substrate to be processed is installed on a control flat plate electrode in a grounded processing chamber, and high-frequency power is applied to a high-frequency applying electrode of a flat plate type which is arranged so as to face the substrate to be processed. Plasma processing method for forming a magnetic field parallel to the flat plate surface of. 2. A substrate to be processed is placed on a control plate electrode in a grounded processing chamber, and high-frequency power is applied to a cylindrical high-frequency applying electrode arranged so that its central axis is perpendicular to the substrate to be processed, A plasma processing method in which a cylindrical ground electrode having the same central axis as that of the high-frequency applying electrode is grounded, and a divergent magnetic field is formed from the high-frequency applying electrode and the ground electrode to the substrate to be processed. 3. A substrate to be processed is placed on a control plate electrode in a grounded processing chamber, and high-frequency power is applied to a cylindrical high-frequency applying electrode arranged so that its central axis is perpendicular to the substrate to be processed, A plasma processing method in which a cylindrical ground electrode having the same central axis as that of the high-frequency applying electrode is grounded, and a parallel magnetic field is formed from the high-frequency applying electrode and the ground electrode to the substrate to be processed. 4. A substrate to be processed is placed on a control plate electrode in a grounded processing chamber, and high frequency power is applied to a cylindrical high frequency applying electrode arranged so that the central axis is perpendicular to the substrate to be processed, A plasma processing method in which a cylindrical ground electrode having the same central axis as that of the high-frequency applying electrode is grounded, and a cusp magnetic field is formed between the high-frequency applying electrode and the ground electrode and the substrate to be processed. 5. A grounded processing chamber, a flat plate-type high-frequency applying electrode which is arranged to face the substrate to be processed and to which high-frequency power is applied, and which is arranged to face the high-frequency applying electrode through the substrate to be processed and which is to be treated. A plasma processing apparatus comprising: a control flat plate electrode on which a processing substrate is installed; and a magnetic field generator that generates a magnetic field parallel to the flat plate surface of the high frequency applying electrode. 6. A grounded processing chamber, a cylindrical high-frequency applying electrode to which a high-frequency power is applied and arranged so that the central axis is perpendicular to the substrate to be processed, and the central axis is the same as the high-frequency applying electrode. A cylindrical ground electrode, a control plate electrode on which the substrate to be processed is placed, and a magnetic field generated in a direction parallel to the central axes of the high-frequency applying electrode and the ground electrode, which are arranged in the vicinity of the high-frequency applying electrode and the ground electrode. And a cylindrical electrode-side magnetic field generator for plasma processing. 7. The plasma processing apparatus according to claim 6, further comprising a substrate-side magnetic field generator which is disposed near the substrate to be processed and generates a magnetic field in a direction parallel to the central axes of the high-frequency applying electrode and the ground electrode.