JP2003031175A - Ion beam processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion beam processing device uniformly neutralizing ion beam of big current.low voltage, restraining divergence of ion beam, with few damage caused by the electrification of a base board. SOLUTION: For the ion beam processing device processing ion beam by irradiating ion beam 52, a high frequency power is impressed on a coil-shaped antenna 30 arranged so as to surround the circumference of the ion beam 52, and neutralizing plasma is generated in the space surrounded by the coil-shaped antenna 30, so that the potential of the space become negative against a processing chamber 3 or a base board holder 41, and electron is surely and sufficiently supplied to the ion beam 52 from the neutralizing plasma by dint of a cylinder-shaped ion trapping electrode 31 facing the neutralizing plasma, having slits in the direction vertical to the winding direction of the coil-shaped antenna 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion beam processing apparatus for ion beam etching, ion beam sputtering, ion beam assist, etc.,
In particular, it relates to neutralization means.

[0002]

2. Description of the Related Art As a conventional technique of this type of ion beam processing apparatus, for example, there is one disclosed as an etching apparatus as disclosed in Japanese Patent Application Laid-Open No. 8-107101. In this conventional technique, each of the plasma generation chamber and the substrate processing chamber has a coil-shaped high-frequency electrode wound on an outer wall for generating plasma, and is partitioned by a ground electrode plate having a plurality of holes. The plasma generation chamber has a structure having a high-frequency electrode plate on the surface facing the ground electrode plate.
Generally, when a high frequency is applied to the substrate mounting table in order to accelerate ions from the plasma toward the substrate, a spatial distribution of the plasma potential above the substrate is generated toward the processing chamber wall that is grounded, and local distribution on the substrate occurs. May cause a charge-up to occur, resulting in element destruction of the substrate to be processed. With the above configuration, by generating plasma in the plasma generation chamber and applying high frequency to the high frequency electrode plate, the upstream plasma potential becomes high, and ions can be extracted into the downstream processing chamber through the plurality of holes. Therefore, ion etching is possible. Since no high frequency is applied to the substrate mounting table, no spatial distribution is generated in the plasma potential above the substrate. Further, the ions in the plasma generated in the processing chamber are neutralized, and the increase in plasma potential is suppressed, so that charge-up can be suppressed.

Further, Japanese Patent Laid-Open No. 11-354508 discloses an ion beam processing apparatus having a negatively biased ion collecting electrode.

[0004]

By the way, in the ion beam processing apparatus for accelerating the ions to anisotropically etch the substrate as described above, particularly in the milling apparatus, etc., the etching rate has angle dependence and In order to prevent the reattachment of the sputtered material to the side walls of the groove or hole of the pattern, the substrate may be tilted and the ions may be obliquely incident. Further, in order to compensate the non-uniformity of the ion beam distribution and ensure the uniformity of the etching rate distribution, the substrate holder that holds the substrate is often rotated. Furthermore, within the range where the ion beam is irradiated, the plurality of substrate holders are rotated around their axes to improve the uniformity of etching distribution. In such a device,
Since the substrate mounting table makes a mechanical movement, it is not called a substrate mounting table but is called a substrate holder here.

In the ion beam processing apparatus having such a substrate holder, it is difficult to insulate the substrate holder from the processing chamber and keep it floating from the ground potential because of its mechanical structure. The substrate holder is generally made to have the same ground potential as the processing chamber.

In the conventional technique disclosed in Japanese Patent Laid-Open No. 8-107101, the substrate mounting table is installed insulated from the processing chamber via a capacitor, and the substrate mounting table is mounted with respect to a plasma potential higher than the ground potential. The table itself was charged to self-adjust the potential to avoid charge-up of the substrate itself. Further, the plasma generated on the front surface of the substrate makes the potential distribution between the elements on the substrate uniform and avoids element destruction, but the potential of the plasma is not controlled. Generally, a large current beam requires a large number of electrons for its neutralization, and its supply must be as large as the number of electrons to be supplied from the neutralizing plasma unless a large number of ions are collected. I can't do it. In the above-mentioned conventional technique, the ion collecting electrode which plays this role corresponds to the grounded extraction electrode, and its collecting area is limited. The potential is also constant. Therefore, when the beam becomes a large current beam and the amount of collected ions becomes insufficient, the plasma potential increases, so that the amount of collected ions is increased and electrons are adjusted to be supplied to the ion beam. Since the plasma potential rises in this way, when the substrate holder is at the ground potential, the above-mentioned conventional technique faces the plasma with a conductive substrate having an insulating thin film such as alumina or an insulating film pattern. A potential difference may be generated between the surface of the insulating film and the surface of the substrate facing the grounded retainer, and in some cases, dielectric breakdown may occur between them.

Further, in particular, in the case of a low-speed beam of 100 eV or less, in order to suppress the divergence of the beam due to self-charge, it is of course necessary to uniformly neutralize the beam. It works to promote the divergence of the ion beam. This transports the ion beam especially for 1 m or more, and has a great influence in a large-sized system that performs ion beam assist.

Further, the prior art disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 11-354508 is based on the local introduction of μ waves.
Since the ring-shaped neutralization plasma is generated, when the ion beam diameter is small, the neutralization plasma may not come into contact with the ion beam and neutralization may not be effectively performed.

In view of the above-mentioned problems of the prior art, an object of the present invention is to reliably and sufficiently neutralize a large current / low voltage ion beam, suppress ion beam divergence, and achieve an ion beam at a long distance. An object of the present invention is to provide an ion beam processing apparatus that enables processing and realizes ion beam processing with low damage to a substrate.

[0010]

According to the present invention, an ion source for generating an ion beam, a processing chamber for irradiating the substrate or target with the ion beam for ion beam processing, and an ion beam for electrically controlling the ion beam are provided. In the ion beam processing apparatus having a neutralizing means for neutralizing, the ion beam neutralizing means is arranged so as to surround the periphery of the ion beam, and has a coil shape for generating neutralizing plasma by applying high frequency power. An antenna and an ion collecting electrode that is installed adjacent to the coiled antenna and that collects ions from the neutralizing plasma by applying a negative potential to the processing chamber or a substrate holder in the processing chamber. It is characterized by having.

The ion collecting electrode is arranged so that the electromagnetic coupling with the coil antenna of itself is weaker than the electromagnetic coupling between the neutralizing plasma and the coil antenna. The ion-collecting electrode has a distance larger than the distance between the coil-shaped antenna and the neutralizing plasma (outer edge). In other words, the electromagnetic coupling with the neutralizing plasma is stronger than the coupling with the ion collecting electrode when viewed from the coiled antenna.

Alternatively, a cylindrical or strip-shaped electrode having a slit extending in the axial direction with respect to the winding direction of the coiled antenna or consisting of a collection of strip-shaped electrodes extending in the axial direction, the electrode being arranged in the circumferential direction of the electrode. The continuous portion satisfies the above condition. Furthermore, in an ion beam processing apparatus equipped with an ion source having an ion extraction electrode,
Among the extraction electrodes of the ion source, the electrode closest to the processing chamber is given a negative potential to the processing chamber or the substrate holder, whereby the ion collecting area can be further increased.

More preferably, in order to prevent the coiled antenna from being damaged by discharge due to neutralizing plasma, a cylindrical dielectric wall made of quartz or the like is installed inside the coiled antenna, and the negative potential ions are provided inside thereof. It is desirable to construct an ion beam processing apparatus by installing a collection electrode.

Furthermore, in order to obtain a gas pressure necessary for maintaining plasma when used in a high vacuum, it is possible to provide a means having a double cylindrical structure with both ends closed and a gas flow therethrough. . Electrons can be supplied to the ion beam by drawing out electrons from holes or gaps provided in the inner cylinder. Depending on the case, an electrode for extracting electrons, which is given a positive potential with respect to the ion collecting electrode, may be used.

Alternatively, in the same manner as above, in a high vacuum where the gas pressure is low, in order to suppress and maintain the diffusion of plasma, a means for generating a magnetic field is provided in a portion adjacent to the coiled antenna, and the generated plasma is confined. The present invention can be made effective.

Since the present invention is configured as described above, when the ion beam generated by the ion source irradiates the substrate or the target in the processing chamber, the neutralizing means surrounds the ion beam to surround the ion beam. A neutralizing plasma is generated in the entire inner space of the ion beam, and the ion beam penetrates the neutralizing plasma and surely contacts. Then, electrons are supplied from the neutralization plasma to the ion beam, beam plasma is formed, and the ion beam is neutralized. In neutralizing such an ion beam, it is important that the neutralizing plasma comes into contact with the ion beam, and even if the neutralizing plasma is generated, it cannot be neutralized unless it comes into contact with the ion beam. At this time, since the ion-collecting electrode facing the neutralizing plasma is set to a negative potential with respect to the processing chamber or substrate holder to which the ion beam is irradiated, the low-speed ions in the neutralizing plasma are transferred to the processing chamber or the substrate. This electrode, which has a lower potential than the holder, can be collected, and the same amount of electrons as the collected ions are uniformly supplied from the neutralizing plasma toward the ion beam.

In this way, the neutralizing means has the following 4
Have one effect. 1) The electrons are uniformly supplied to the ion beam. Neutralizing plasma is generated in the entire region through which the ion beam passes, so that more uniform electron supply can be performed and the charging of the substrate can be suppressed uniformly and lower than that of a hollow cathode or a plasma bridge neutralizer that locally supplies electrons. 2) A large amount of electrons can be stably supplied even to a large current beam. The ion-collecting electrode has a cylindrical or band-like shape facing the plasma or a perforated disk, or an electrode closest to the processing chamber of the extraction electrode of the ion source is used as the ion-collecting electrode, so that the ion-collecting area can be increased. It can be easily widened. Therefore, it is possible to reliably collect a sufficient amount of ions from the neutralized plasma only by generating the low density neutralized plasma, and to collect the ions into the substrate holder or the processing chamber irradiated with the ion beam. By setting the electrode to a negative potential, a sufficient amount of electrons can be supplied to the ion beam side. Here, the cylindrical or strip-shaped electrode is formed by forming a slit in the axial direction of the coiled antenna or by forming a strip-shaped electrode to avoid electromagnetic coupling between this electrode and the coiled antenna. Therefore, the high frequency power can be effectively supplied to the plasma. At the same time, an electrode having a larger area can be formed, and a plasma having a lower density, that is, a sufficient amount of high-frequency power to supply electrons can be supplied. Electrons generated by a small amount of high-frequency power have low energy and become plasma with a low electric potential, which is effective in suppressing beam divergence and substrate charging. 3) By adjusting the potential of the beam plasma, dielectric breakdown of the insulating film substrate attached to the grounded substrate holder can be avoided. The negative potential applied to the ion collecting electrode plays the following role. In the absence of the ion-collecting electrode, the potential of the neutralizing plasma is often several tens of volts higher than that of the grounded processing chamber. Therefore, the beam plasma generated by contacting the neutralizing plasma is also a few
When the substrate holder has a potential of 0 V and the substrate holder is grounded, the surface of the conductive substrate having an insulating film may be charged even if electrons are supplied, and dielectric breakdown may occur. Particularly in the case of a large current beam, the amount of electrons supplied, that is, the amount of ions collected from the neutralizing plasma is insufficient, and the plasma potential is likely to rise. In the present invention, the ion-collecting electrode occupies a large area with respect to the neutralized plasma, and since the electrode can be made negative, a large amount of ions can be collected, the rise in plasma potential is suppressed, and this electrode potential The potential of the neutralizing plasma and the beam plasma connected to the neutralizing plasma can be raised or lowered. That is, even if the substrate holder is temporarily grounded, the plasma can be lowered to the ground potential by setting the ion collecting electrode to a negative potential, and the potential of the insulating film surface facing the plasma and the ground potential can be reduced. It is possible to eliminate the potential difference with the conductive underlying substrate. as a result,
It is possible to avoid dielectric breakdown of the insulating thin film on the substrate. 4) It suppresses divergence due to the potential of the beam itself and enables ion beam processing over a long distance. In particular, with a low-speed beam of 100 V or less, divergence due to the self-potential of the ion beam is remarkable. By lowering the potential of the beam plasma, it is possible to suppress such divergence, enable ion beam transportation over a long distance, and perform desired ion beam processing.

Further, under high vacuum, the gas pressure is too low to maintain neutralization plasma, and the plasma density may be extremely low due to diffusion. Therefore, as described above, the dielectric tube of the double cylindrical structure is arranged inside the coiled antenna,
By flowing gas between the cylinders, the gas pressure inside the coiled antenna can be increased. As a result, the plasma can be maintained, and the plasma leaking from the hole or the gap provided in the inner dielectric tube comes into contact with the ion beam to supply electrons to the ion beam. When the gap is too small to allow plasma to exit from the gap between the dielectrics, an electron extraction electrode that can give a positive potential to the ion-collecting electrode is provided inside the dielectric so that electrons can be emitted into the ion beam. Can be given.

As another method under high vacuum, a means for generating a magnetic field is provided in a portion adjacent to the coiled antenna as described above, and the plasma is confined by the magnetic field to suppress the diffusion of the plasma. You can activate one effect.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a vertical cross-sectional view of the overall configuration of a first embodiment using an ion beam processing apparatus according to the present invention, and FIG. 2 (a) is a perspective view of an ion source and neutralizing means in the first embodiment. . In addition, FIG.
FIG. 7 is a perspective view of another form of ion collecting electrode in the first embodiment. FIG. 3A is an enlarged vertical sectional view of a main part of FIG. 1, and FIG. 3B is a side view of the extraction electrode.

In the ion beam processing apparatus according to the first embodiment of the present invention, high frequency is supplied to the coil antenna 17 having four turns, so that the ceramic plates 12 and 13 and the quartz tube 1 can be processed.
The ion source plasma generation chamber 50 defined by 6 has an ion source (not shown) for generating high frequency plasma. The size of the ion source plasma generation chamber 50 is, for example, a cylindrical type having a diameter of 212 mm and a length of 100 mm,
A 13.56 MHz high frequency power supply 19 is attached to the coiled antenna via a matching unit 18. The ion source body is contained in a metal vacuum chamber 2,
The vacuum chamber 2 is connected to the processing chamber 3 that performs the ion beam processing on the substrate, and constitutes one chamber. Therefore, the high frequency applied to the antenna 17 is shielded by the chamber 2 and does not leak into the atmosphere.
Further, since both the plasma generation chamber 50 and the chamber 2 are evacuated from the processing chamber 3, the quartz tube 16 forming the plasma generation chamber 50 does not need to support the atmospheric pressure, and a thin material can be used.

The ceramic plates 12 and 13 constituting the plasma generating chamber 50 are fixed so as to keep a predetermined distance from each other via a spacer (not shown) and also serve as a gas distributor. These are held by a metal support flange 10, and a gas introduction pipe 14 is attached to the center of the support flange 10. The gas introduced into the ion beam processing apparatus diffuses into the surroundings through the gap between the ceramic plates 12 and 13, and is sent into the plasma generation chamber 50 along the inner wall of the quartz tube 16.

Since the plasma generating chamber 50 is composed of the quartz tube 16 and the ceramic plates 12 and 13, two inexpensive quartz tubes can be used instead of the quartz bell jar, and replacement is easy. Is. Also,
The ceramic plate 13 may be a metal plate, or may be a bias electrode that increases the amount of ions extracted from the plasma. The support flange 10 is fixed by six columns 11 embedded in the ion source flange 1, and the entire ion source is held in the internal space of the chamber 2.

On the other hand, an extraction electrode 20 having a plurality of holes each having a predetermined interval and having a predetermined size is attached to an opening of the plasma generation chamber 50 facing the ceramic plate 13. As shown in FIG. 3 (a), the extraction electrode 20 is formed of electrodes 20a, 20b, 20c having the same holes at the same positions and fixed by insulating spacers (not shown). Has been done. The extraction electrode 20a is installed in the processing chamber
Voltage of about 100-2000V, electrode 20b is -50-
A negative voltage of about −1000 V is applied to extract only ions from the plasma generated in the plasma generation chamber 50 through the holes of these electrodes. The extracted ions are accelerated with energy equivalent to the voltage applied to the extraction electrode 20a.

The region where the plurality of holes of the ion extraction electrode 20 are distributed has a size of 170 mm, for example. Further, the third electrode 20c is connected to the ion collecting electrode 31 and has the same potential.

A neutralizing means is provided on the downstream side of the ion source, that is, on the right side portion of the ion source chamber 2, and the processing chamber 3 is connected further downstream thereof. The neutralizing means is a two-turn coil-shaped antenna 30 for generating neutralizing plasma, which is installed so as to surround the ion beam 52 along the traveling direction of the ion beam 52, and a quartz tube 3 installed inside thereof.
5 and a cylindrical ion collecting electrode 31 inside thereof. On the other hand, the processing chamber 3 is a space for processing an object to be processed 40 such as a substrate by the ion beam 52, and is defined by a grounded metal wall. The processing object 40 is held on a holder 41 connected to the processing chamber 3. The holder 41 is provided with a rotating mechanism that performs a rotational movement to improve the uniformity of the ion beam processing, and is brought to the ground potential by mechanical contact with the processing chamber 3.

The antenna 30 of the neutralizing means has 13.56M
A high frequency power supply 33 of Hz is connected through a matching unit 32,
A high frequency plasma that neutralizes the ion beam 52 is generated in the space formed by the electrode 31. Also,
The ion collection electrode 31 is given a negative potential of about 0 to -50 V to the processing chamber 3 and the holder 41 by the DC power supply 36. These are supported by the support flange 34 and the support 11
Attached to the ion source, it forms an integral structure with the ion source, and plasma is generated immediately after the ion source exits for efficient neutralization. The size of the space chamber 51 in which the neutralizing plasma is generated is 230 mm in diameter.
mm and length 80 mm. The ion collecting electrode 31 is, for example, a tubular type having a slit with a width of 2 mm in a direction perpendicular to the winding direction of the coiled antenna 30. The slit 31d of the ion collecting electrode 31 blocks a circumferentially induced current in the electrode 31 caused by a high-frequency current flowing in the coil antenna 30, and a power loss due to electromagnetic coupling between the coil antenna 30 and the electrode 31. Is to reduce. That is, as seen from the coiled antenna 30, the electromagnetic coupling with the neutralizing plasma 56 causes the ion collecting electrode 3
By making it stronger than the coupling with 1, the high frequency power applied to the coiled antenna 30 is effectively injected into the neutralization plasma 56.

This slitted electrode 31 is shown in FIG.
The electrode may be composed of a set of strip-shaped electrodes that are long in the direction perpendicular to the winding direction of the coil as shown in FIG.

Further, the electrode 31 does not necessarily have to be a circumferentially discontinuous electrode such as an electrode with a slit as long as it faces the neutralizing plasma, and an ion that can supply electrons necessary for neutralization can be used. If the collection area can be secured, the coil-shaped antenna 30 may be avoided as in the embodiments of FIGS. 4 and 6 described later, and a cylindrical or disk-shaped ring-shaped electrode may be arranged in front of and behind it.

FIG. 5 is an enlarged cross-sectional view of an essential part of FIGS. 4 and 6.
7B, the distance xe between the coiled antenna 30 and the ion collecting electrode 31, the coiled antenna 30
When the distance xp between the neutralization plasma 56 and
(B), these practical values in the ion collecting electrode 31 shown in FIG. 7 (b) are the same as those of the ion collecting electrode 31 when electromagnetic coupling with the neutralizing plasma 56 is seen from the coiled antenna 30. It is desirable to satisfy xp << xe so that it is stronger than the bond. In the example of the slit electrode 31 and the strip electrode 31e shown in FIGS. 3A and 3B, xe is considered to be the distance between the circumferentially continuous portion and the coiled antenna 30.

In the present embodiment, in order to protect the coil 30 from the neutralizing plasma 56 and to keep the gas pressure in the neutralizing plasma generating space as high as possible, as shown in FIG. A quartz tube 35 is disposed between the coil antenna 30 and the coil antenna 30. The quartz tube 35 is also used as a structural member, but when the ion collecting electrode 31 is used as a structural member, and the coiled antenna 30 is used.
, Is subjected to insulating surface treatment such as ceramic coating or plasma resistant surface treatment such as platinum coating,
The quartz tube 35 may be omitted. In this case, the coiled antenna 30 may be inside the ion collecting electrode 31. By the way, the quartz tube 35 and the electrode 31 have a thickness of 0.
Since the quartz tube 35 is installed with a space of 5 mm or more, even if the quartz tube 35 is contaminated with conductive deposits through the slits of the electrodes, the deposits do not conduct to the electrodes 31 and the circumferential direction of the electrodes 31 is reduced. The induction current does not cause a decrease in high frequency input efficiency. Therefore, the maintenance cycle is significantly extended. The electrode 31 is made of molybdenum, and the increase in radius due to thermal expansion of the electrode 31 is effective for radiation cooling.
Even if it reaches about 0 ° C, it is less than 0.5 mm. Therefore, a gap of 0.5 mm is sufficient. However,
If it is opened too much, energy cannot be effectively input to the plasma, which is not desirable.

In this embodiment, the coil antenna 3 is used.
The high frequency applied to 0 is 13.56 MHz, but in order to avoid mutual interference between the high frequency supplied to the ion source and the high frequency supplied to the neutralizer side, each high frequency is set to 0.
It is desirable to shift by about 01 to 1 MHz or to connect so as to adjust the phase of each high frequency using a phase shifter or the like.

Next, the operation of the first embodiment of the present invention will be described. First, a vacuum pump (not shown) is used for the processing chamber 3 to evacuate the chamber 1 × 10 −4.
It is set to Pa or less. Then 50 W for the coil antenna 17
High frequency power is supplied, and argon gas is instantaneously introduced into the ion source plasma generation chamber 50 from the gas introduction pipe 14 in a pulsed manner, and then the pressure in the plasma generation chamber 50 is increased to 4 to 8
A desired gas is flowed at a flow rate of about 10-2 Pa. Generally, the inductively coupled plasma generated by such a coil antenna causes self-ignition to a comma number Pa to several P.
Although a gas pressure of about a or seed electrons is required, the gas pressure in the plasma generation chamber instantaneously rises to the comma number Pa by the pulsed argon gas, and the plasma is ignited. Since the gas introduced from the gas introduction pipe 14 is sent to the peripheral portion of the plasma generation chamber 50 by the ceramic plates 12 and 13 which play the role of the gas distributor, the gas pressure in the vicinity of the antenna 17 rises and the efficiency is improved. Plasma ignition is performed. In the plasma generation chamber, electrons in the plasma are heated by the circumferential induction field generated by the applied high frequency,
Since the introduced gas molecules are subjected to impact ionization, a high density plasma is maintained. After plasma ignition, a desired gas used in the ion beam treatment, for example, oxygen gas, is introduced into the gas introduction tube 1
Introduced from 4.

After the plasma is stabilized, the extraction electrode 20a of the ion source is connected to the + of the DC power source 21 in the processing chamber 3.
When the ion source plasma is set to a positive potential by being connected to the pole and the ion extraction electrode 20b is set to a negative potential, only ions are extracted from the high-density plasma in the plasma generation chamber 50 by the ion extraction electrode 20b. The ion beam 52 is extracted to the processing chamber 3 side. The extracted ion beam 52 is neutralized by the neutralizing means formed by the coiled antenna 30 and the cylindrical ion collecting electrode 31, and is irradiated to the object 40 to be processed, thereby performing the desired processing. . In the neutralizing means, a neutralizing plasma is generated in the internal space by the high frequency antenna 30 like the ion source, and the ion beam passing through the plasma is collected by the ion collecting electrode while the low-speed ions in the plasma are collected. The same amount of electrons is supplied to 52, and the ion beam 52
Electrically neutralize. Since the ion collecting electrode 31 has slits in the direction perpendicular to the winding direction of the coil, an induced current in the circumferential direction does not flow, and the plasma 56 is emitted from the antenna 30.
Does not interfere with the transmission of high frequency power to.

Next, the neutralizing action of the neutralizing means will be described. When the ion beam is extracted from the ion extraction electrode 20, the ion beam collides with the extraction electrode 20 and the like, and secondary electrons are emitted, or the extracted ion beam ionizes the neutral gas in the space and the secondary electrons are emitted. Since these electrons become seed electrons and a high frequency of about 50 W is supplied to the coiled antenna 30 in the neutralizing means, plasma is ignited in the neutralizing plasma generating region 51. If it is difficult to ignite, it is possible to ignite by separately installing a gas introduction pipe 37 (see FIG. 7 (b)) and introducing a gas pulse into the ion collecting electrode, similarly to the ion source. After ignition, the plasma is maintained by inductively heating the electrons of the generated plasma. However, since the gas pressure is low, the plasma density is smaller than that of the ion source.

As described above, when the neutralization plasma 56 is generated, the ion beam 52 becomes a beam plasma in which electrons are supplied from the plasma 56. Since the ion collector electrode 31 is set to a negative potential by the DC power supply 36 with respect to the holder 41 and the processing chamber 3 which are irradiated with the ion beam, that is, facing the beam plasma, the low-speed ions in the neutralizing plasma are 54 can be collected by the ion collecting electrode 31. Then, the electrons 53 having the same charge as the collected ions can be supplied to the ion beam 52. By supplying the neutralizing electrons, it is possible to suppress the variation in the potential distribution on the substrate irradiated with the ion beam and avoid the element destruction. Further, since the neutralization plasma 56 is generated over the entire area surrounded by the ion collecting electrode 31, it surely contacts the ion beam 52 and exhibits the above-mentioned neutralizing action.

The cylindrical shape of the ion-collecting electrode 31 widens the ion-collecting area and only produces a low-density neutralizing plasma, so that a sufficient amount of ions can be reliably collected from the plasma. The ion beam 52 can be supplied with a sufficient amount of electrons. In this case, since it is sufficient to generate a low-density neutralization plasma, a small amount of high-frequency power needs to be introduced, the neutralization plasma becomes a quiet plasma with a low electron temperature, and the energy of electrons supplied from this is small, so that the beam The potential of plasma can be kept low.
That is, the influence of the potential of the beam plasma on the low-speed beam can be reduced as much as possible, and the divergence of the beam can be suppressed.

Here, the negative potential applied to the ion collecting electrode 31 plays the following role. When the ion-collecting electrode 31 is not provided, the ion-collecting electrode serves as an extraction electrode having a ground potential, and the amount of supplied electrons becomes insufficient, and at the same time, the amount of collecting ions becomes insufficient, so that the potential of plasma increases. In many cases, the potential of the neutralizing plasma is several tens of volts, for example 5 from the grounded processing chamber 3.
It becomes about 0V higher. Therefore, when the cage 41 is grounded, the surface of the insulating film of the conductive substrate having the insulating thin film is charged to about 30 V, which may cause dielectric breakdown of the insulating thin film. In the present invention, since the ion-collecting electrode 31 occupies a large area with respect to the neutralization plasma, sufficient electrons can be supplied, and the potential of the plasma itself is lowered. The potential of the beam plasma connected to the plasma can be raised or lowered. That is, even if the holder 41 is grounded, the potential of the plasma can be lowered to the ground potential by setting the electrode 31 to a negative potential. By such adjustment, it is possible to eliminate the potential difference between the potential on the surface of the insulating film and the conductive underlying substrate at the ground potential, and it is possible to avoid dielectric breakdown. Further, since the potential of the beam plasma is lowered, the divergence due to the potential of the beam itself can be suppressed particularly in a low-speed beam of 100 V or less, and the ion beam processing can be performed over a long distance.

Furthermore, the embodiment has the following operational effects. That is, the coiled antenna 30, the ion collecting electrode 3
Since 1 is arranged at a position immediately after the extraction of the beam extracted by the ion extraction electrode 20 in the extraction direction of the ion beam, as compared with the case where it is arranged on the downstream side, for example, in the vicinity of the object 40 to be processed, 1) It is easy to suppress the divergence of the beam, 2) the object 40 to be processed is not exposed to neutralizing plasma, 3) there is an effect that the vicinity of the object to be processed is easily exhausted and a large exhaust conductance can be obtained.

When used in a reactive gas atmosphere,
The ion collecting electrode 31 may be covered with an insulator such as an oxide, but by applying an appropriate negative potential, self-cleaning by sputtering can be performed. Of course, the function of the ion-collecting electrode 31 is not impaired even if conductive deposits are attached, and because the quartz tube 35 is installed with a distance of 0.5 mm, the conductive attachment attached to the quartz wall through the slits. The kimono does not conduct in the circumferential direction and does not impair the efficiency by coupling with the coiled antenna. In this way, it can be used in a reactive gas atmosphere, and since there are no consumables such as filaments and thermionic emission materials, the maintenance cycle can be significantly lengthened. Furthermore, it has the feature that the heat load on the substrate and ion source is small, and there is no heavy metal contamination due to tungsten filaments.

Next, second and third embodiments of the present invention will be described with reference to FIGS. These are the ion-collecting electrodes 31 in FIG. 1 which are not tubular electrodes with slits but take another form. The second electrode shown in FIGS.
In the second embodiment, the ion collecting electrode 31a is composed of two cylindrical electrodes arranged so as to avoid the inside of the coiled antenna. In the third embodiment shown in FIGS. 6 to 7, the ion collecting electrode 31b is It is composed of two perforated disc-shaped electrodes provided before and after the quartz tube 35b.

These ion-collecting electrodes 31a and 31b are both facing the neutralizing plasma 56 but far from the neutralizing plasma 56 when viewed from the coiled antenna 30, and are slightly electromagnetically coupled to the antenna 30. However, it is in an arrangement that is more difficult to electromagnetically couple than the neutralizing plasma 56. Even if it does not have a slit, it functions as an ion-collecting electrode without hindering the transmission of high-frequency power.

In FIG. 7B, a gas introducing pipe 37 is installed inside the quartz pipe 35b. If the neutralization plasma does not ignite, it is possible to ignite it by instantaneously introducing a pulsed gas from here. When it is desired to increase the density of the neutralization plasma, it is preferable to provide such a gas introduction pipe around the entire circumference and supply the gas to the inner wall of the quartz pipe 35b during the ion beam treatment.

Next, a fourth embodiment will be described with reference to FIG. In the case of processing a plurality of substrates at the same time like the ion beam processing apparatus shown in FIG. 8, it is necessary to radiate the ion beam at a wide angle. In the first embodiment, a cylindrical electrode was used as the ion collecting electrode, but in this case, the ion beam hits the end of the neutralizing means, which is not preferable. for that reason,
By disposing the ion collecting electrode 31 and the coiled antenna 30 like a truncated cone, it is possible to prevent the ion beam from colliding. According to the principle of the present invention, such a shape does not affect the neutralizing property of the ion beam. Therefore, it can be easily inferred that it has the same effect as the present invention.

In the present invention, the neutralizing means has an open end on the processing chamber side. Therefore, when used in a high vacuum such as ion beam sputtering, the neutralizing plasma is maintained in the above embodiment. It can be difficult. To maintain the plasma, a gas pressure is secured in the neutralization plasma generation chamber. Suppresses plasma diffusion. It suffices if either one of the conditions is satisfied. Therefore, Embodiments 5 to 7 of the present invention when applied under high vacuum are described in FIGS.
Will be explained.

First, the fifth embodiment will be described with reference to FIG. FIG. 9 (a) is an enlarged cross-sectional view of a main part of the neutralization plasma generation chamber, in which a gas pressure is secured to facilitate neutralization plasma ignition. Another quartz tube 35d is provided inside the quartz tube 35 in the first embodiment, and the front and rear of the quartz tube 35d are closed by a flange, and gas is supplied into the space chamber sandwiched between the quartz tubes, whereby The gas pressure is made higher than that in the processing chamber, and the neutralization plasma 56 is generated. On the other hand, a gap 35e such as a plurality of holes or slits is provided in the inner cylinder, and the plasma exuding from the gap 35e comes into contact with the ion beam 52 to supply the neutralizing electrons 53. In the neutralization plasma generation chamber 51, there is an ion collecting electrode 31 with a slit as in the first embodiment, and ions are collected from the neutralization plasma 56. If the gap 35e becomes small to maintain the gas pressure and the plasma cannot exude, the inner quartz tube 35d
Electrons can be extracted and supplied to the ion beam 52 by providing an electron extraction electrode 39 having a positive potential with respect to the ion collection electrode inside the.

FIG. 9B shows a gap 35e for drawing out electrons.
FIG. 4 is a cross-sectional view taken along the radial direction in FIG. Neutralizing electron 53
Is supplied from the entire circumference toward the central ion beam 52 from the ring-shaped plasma generated between the two quartz tubes 35 and 35d, and uniform neutralization can be obtained.

Next, regarding the sixth and seventh embodiments, FIG.
0 and FIG. 11 will be described. In these examples, the neutralization plasma generated by the magnetic field is suppressed from diffusing, a high density plasma is maintained, and the present invention can be carried out even under a high vacuum.

FIG. 10A is an enlarged sectional view of the essential parts of the sixth embodiment.

As shown in FIG. 10, the coiled antenna 3
Before and after 0, permanent magnets 60 and 61 having polarities different from each other are arranged in two rows in a ring shape along the circumference of the quartz tube 35b, and the inside of the neutralization plasma generation chamber 51 is shown in FIG. A cusp magnetic field like the magnetic field lines 63 is formed. In induction discharge by high frequency, only a very thin plasma can be generated under high vacuum, but the diffusion of electrons is suppressed by the magnetic field lines 63, and the generated plasma is confined in the magnetic field lines to locally form a dense plasma region. be able to. On the other hand, in induction discharge by high frequency, electrons are hard to move under high vacuum and strong magnetic field, so that plasma is hard to be generated. In this case, the density of plasma increases due to plasma confinement as well as the decrease in plasma generation efficiency due to electron binding.

That is, during plasma generation, an appropriate mean free path of electrons and heating of electrons are obtained, and a dense plasma is generated in a region having a magnetic field strength sufficient to bind the electrons, which is shown in FIG. As shown in b), it is formed in a ring shape around the ion beam 52. On the other hand, since thin plasma is generated around the ring-shaped dense plasma region, it reliably contacts the ion beam 52. An ion collecting electrode 31b is provided in front of and behind the ring-shaped plasma 56b, and the ring-shaped plasma 56b, which is a dense plasma, is used as an electron source for the electrode 3a.
The same amount of electrons as the ions collected in 1b are generated by the ion beam 52.
Is supplied to. However, in this case, unlike the third embodiment, the flange 34b for fixing the quartz tube 35b also has the processing chamber 3 or the substrate holder 41 similarly to the ion collecting electrode 31b.
Is set to a negative potential. This is the magnet 6 along the line of magnetic force.
This is to prevent the electrons flowing near 0 and 61 from being absorbed by the flange 34b, thereby improving the emission efficiency of electrons to the ion beam. Further, by arranging the permanent magnet 60 in this way, a strong magnetic field region can be brought to the outside of the coiled antenna 30.
It becomes difficult for the plasma to reach the outside, and high frequency power can be applied to the inner neutralization region.

FIG. 11 shows the seventh embodiment, and FIG.
(A) is an enlarged cross-sectional view of the main part thereof. This example
A permanent magnet is arranged on the processing chamber side of the neutralizing means, that is, on the open end side to form a quadrupole magnetic field as shown in FIG. 11 (b). The ion collecting electrode 31b is similar to that of the previous embodiment, FIG. When generating and confining the neutralizing plasma 56, it is not always necessary to form a cusp magnetic field as shown in FIG. It is sufficient to create a magnetic field wall on the plasma diffusion side.

The induction discharge plasma obtained by applying a high frequency to the coiled antenna 30 is mainly generated in the vicinity of the coil, that is, in the peripheral portion of the plasma generation chamber 51. Therefore, by providing a magnetic field around the open end, it is possible to efficiently confine the electrons and maintain a relatively dense plasma even under high vacuum. The flange 34b for fixing the permanent magnet 62 and the quartz tube 35b is set to a negative potential with respect to the processing chamber 3 or the substrate holder 41, like the ion collecting electrode 31b. As a result, the electrons that have flowed along the lines of magnetic force are repelled, and electrons are easily emitted from the weak magnetic field region near the center to the ion beam 52.

That is, the electrons are confined in the peripheral portion where the neutralizing plasma is generated, the electrons easily flow near the center where the ion beam exists, and the magnetic field is arranged to easily supply the electrons. Although it is inferior to the previous embodiment in terms of uniform supply of neutralizing electrons, since a large amount of electrons can be supplied as compared with the previous embodiment, if the substrate 40 for irradiating the ion beam is relatively far from the ion source, there is almost no magnetic field, The electrons diffuse and become sufficiently uniform. Further, as the beam plasma, since the ion beam is coupled with the neutralizing plasma biased to a negative potential, the potential on the substrate can be controlled as described above, and the insulation of the insulating thin film on the substrate surface, which is the object of the present invention, can be achieved. You can prevent destruction.

[0055]

As described above, according to the present invention, since the neutralizing plasma is generated in the entire region where the ion beam is present, the neutralizing plasma is surely contacted with the ion beam regardless of the diameter of the ion beam, and is uniform. The electrons can be supplied to the ion beam side. Further, by collecting the ions in the tubular electrode, it is possible to widen the area for collecting the ions, and to collect a sufficient amount of ions from the plasma, that is, a sufficient amount of electrons for a large current beam. We can supply. By adjusting the potential of the ion collecting electrode to be negative, the potential of the beam plasma and the surface of the substrate can be adjusted, so that the charging of the substrate is made uniform and reduced, and the pattern damage of the substrate and the insulating thin film on the substrate surface It can prevent the dielectric breakdown. Further, the potential rise in the beam plasma is suppressed, and the divergence of the ion beam can be suppressed as much as possible in the low voltage, high current beam. Furthermore, since the means for generating the neutralization plasma can have a very simple structure, it can be easily applied to an existing ion beam processing apparatus.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of the overall configuration of a first embodiment using an ion beam processing apparatus according to the present invention.

FIG. 2 (a) is a perspective view of an ion source and a neutralizing means in the first embodiment, and FIG. 2 (b) is a perspective view of an ion collecting electrode having a different form from the first embodiment. is there.

3 (a) is an enlarged vertical cross-sectional view of a main part of FIG. 1, (b).
FIG. 4B is also a front view of the extraction electrode.

FIG. 4 is a vertical cross-sectional view of the overall configuration showing a second embodiment according to the present invention.

5A is an ion-collecting electrode according to the second embodiment, and FIG. 5B is an enlarged cross-sectional view of a main part thereof.

FIG. 6 is a vertical cross-sectional view of the overall configuration showing a third embodiment according to the present invention.

7A is an ion-collecting electrode in a third embodiment, and FIG. 7B is an enlarged sectional view of a main part thereof.

FIG. 8 is a vertical cross-sectional view of the overall configuration showing a fourth embodiment according to the present invention.

9A is an enlarged cross-sectional view of a main part showing a fifth embodiment according to the present invention, and FIG. 9B is a radial cross-sectional view of a neutralization plasma generation part.

10A is an enlarged cross-sectional view of a main part showing a sixth embodiment according to the present invention, and FIG. 10B is a radial cross-sectional view of a neutralization plasma generation part.

FIG. 11A is an enlarged cross-sectional view of an essential part showing a seventh embodiment according to the present invention, and FIG. 11B is a view showing a magnet arrangement.

[Explanation of symbols]

1 ... Ion source flange 2 ... Ion source chamber
3 ... Processing chamber 10 ... Support flange 11 ... Strut 1
2, 13 ... Gas distributor 14 ... Gas inlet pipe 15, 15
b ... Connection flange 16 ... Ion source quartz tube 17 ...
Coil-shaped antenna for ion source plasma generation 18 ... Matching device 19 ... High frequency power source 20 ... Ion extraction electrode 20a ... Extraction electrode 1 20b ... Extraction electrode 2
20c ... Extractor electrode 3 21 ... Acceleration power supply 30,
30c ... Coiled antenna for neutralizing plasma generation 31,
31a, 31b, 31c, 31e ... Ion collection electrode 31
d ... Slit 32 ... Matching device 33 ... High frequency power supply
34, 34b ... Support flanges 35, 35c, 35d ... Neutralizer quartz tube 35e ... Gap
36 ... Neutralizer power supply 37 ... Gas introduction pipe 38 ... Insulating spacer 39 ... Electron extraction electrode 40, 40c ... Object to be treated 41, 41
c ... Retainer 50 ... Ion source plasma generation chamber 51 ... Neutralizer plasma generation chamber 52 ... Ion beam
53 ... Neutralizing plasma electron 54 ... Neutralizing plasma ion 55 ... Ion source plasma 56 ... Neutralizing plasma 6
0,61,62 ... Permanent magnet 63 ... Magnetic field lines.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/3065 H05H 3/00 H05H 3/00 H01L 21/302 D (72) Inventor Satoshi Ichimura Ibaraki Hitachi City Omika-cho 7-2-1 Co., Ltd. Hitachi, Ltd. Power & Electric Machinery Development Laboratory (72) Inventor Tadashi Sato 7-chome, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Electric Power & Electric Machinery Development Research In-house F-term (reference) 2G085 BA02 BE10 DA03 4K029 DC37 DE02 DE03 DE05 5C034 BB09 BB10 5F004 AA06 BA11 BA20 BB07 BB11 BB13 DA23 DA26

Claims (12)

[Claims] 1. An ion source for generating an ion beam, a processing chamber for irradiating the substrate or target with the ion beam for ion beam processing, and a neutralizing means for electrically neutralizing the ion beam. In the ion beam processing device, the ion beam neutralizing means is disposed so as to surround the ion beam, and a coil-shaped antenna that generates neutralization plasma by applying high-frequency power, and the coil-shaped antenna An ion, which is installed adjacent to each other and has an ion collecting electrode for collecting ions from the neutralizing plasma by applying a negative potential to the processing chamber or a substrate holder in the processing chamber. Beam processing equipment. 2. The ion beam processing apparatus according to claim 1, wherein the electromagnetic coupling between the ion collecting electrode and the coil antenna is weaker than the electromagnetic coupling between the coil antenna and the neutralizing plasma. The ion beam processing apparatus according to claim 1, wherein the ion beam processing apparatus is configured as described above. 3. The ion beam processing apparatus according to claim 1, wherein the distance between the coil antenna and the ion collecting electrode is larger than the distance between the coil antenna and the neutralizing plasma. Ion beam processing equipment. 4. The ion beam processing apparatus according to claim 1 or 2, wherein the ion collecting electrode has a slit that is long in an axial direction with respect to a winding direction of the coiled antenna. . 5. The ion beam processing apparatus according to claim 1 or 2, wherein the ion-collecting electrode comprises a set of strip-shaped electrodes that are long in the axial direction with respect to the winding direction of the coil-shaped antenna. An ion beam processing apparatus, which is a strip-shaped electrode. 6. The ion beam processing apparatus according to claim 4 or 5, wherein a distance between a portion of the ion collecting electrode that is continuous in the circumferential direction and the coiled antenna is the neutralized plasma and the coiled antenna. The ion beam processing device is characterized in that it is larger than the distance. 7. The ion beam processing apparatus according to any one of claims 1 to 6, wherein the ion-collecting electrodes are arranged in the inner space of the coiled antenna or in front of and behind the coiled antenna. An ion beam processing apparatus having a dielectric wall in the interior. 8. The ion beam processing apparatus according to claim 7, wherein there is a gap of 0.5 mm or more between the ion collecting electrode and the dielectric wall. 9. The ion beam processing apparatus according to claim 7, wherein the dielectric wall has a coaxial double cylindrical structure with both ends closed, and has means for flowing a gas between the cylinders. An ion beam processing apparatus having one or more holes or gaps in a body wall. 10. The ion beam processing apparatus according to claim 9, further comprising an electron extracting electrode provided inside said inner cylinder for applying a positive potential to said ion collecting electrode. Processing equipment. 11. The ion beam processing apparatus according to claim 1, further comprising magnetic field generating means installed adjacent to the coiled antenna. 12. The ion beam processing apparatus according to any one of claims 1 to 11, further comprising an ion source having a plurality of ion extraction electrodes, the extraction electrode of the ion source being closest to the processing chamber. An ion beam processing apparatus, wherein the electrode has means for giving a negative potential to the processing chamber or the substrate holder.