JP2002216653A - Ion beam distribution control method and ion beam processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion beam distribution control method and an ion beam processing apparatus that can easily control a pulling-out ion beam even under processing and can obtain a uniform ion beam or an ion beam having a predetermined distribution. SOLUTION: This ion beam processing apparatus comprises an ion source 1 having a pulling-out electrode 20 for generating a plasma 50 and pulling out an ion beam from the plasma 50, and a processing room 7 for applying an ion beam process to the substrate 40 by irradiating the ion beam pulled out by the pulling-out electrode 20 to the substrate 40 sustaining the substrate 40. In this ion beam processing apparatus, an electrode 26 in the center of the face opposed to the pulling-out electrode 20 within the ion source 1 and an electrode 27 along the inner radius are arranged. A magnetic field having a vector in the direction of the axis is formed within the ion source 1 and each potential of the electrodes 26, 27 is individually controlled by power supplies 36, 37 independently from the pulling-out electrode 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion beam distribution control method in ion beam etching, ion beam sputtering and the like, and an ion beam processing apparatus.

[0002]

2. Description of the Related Art As a prior art of this type of ion beam processing apparatus, as shown in FIG. 15, for example, as shown in FIG. 15, an ion source 1 for generating plasma and extracting ions, and irradiating the extracted ions to process the substrate or the like. There is an ion milling apparatus including a processing chamber 7 for performing processing. The ion beam processing apparatus is generally provided with an extraction electrode 20 composed of two to three porous electrode plates 20 a to 20 c, and the extraction electrode 20 extracts ions from the plasma 50 in the ion source 1. The extraction electrodes 20 and an electric circuit (not shown) connected to them are collectively called a beam extraction system.

A major characteristic required for such an ion beam processing apparatus is beam uniformity. Due to the principle of the device, the beam distribution is the plasma distribution inside the ion source,
And a beam extraction system using an extraction electrode. The beam extraction system acts as a kind of filter on the plasma distribution, and the beam distribution is obtained by applying the filter to the plasma distribution. From this, there are roughly three methods for obtaining a uniform beam. The first method is to make the plasma distribution in the ion source uniform. The second is adjustment by the beam extraction system. The third method is to directly modify the extracted beam.

[0004] The generation of large diameter uniform plasmas in ion sources has long been studied. That is, the first plasma distribution is made uniform. The ion source portion of the ion beam processing apparatus shown in FIG. 15 is of a so-called bucket type, and generates a large-diameter, relatively uniform plasma by improving the confinement of plasma using a cusp magnetic field. However, the main purpose of the bucket type is to increase the plasma confinement efficiency and generate high-density plasma, and its distribution is arbitrarily determined. That is, although the generated plasma is relatively uniform, no further uniformity can be expected. For this purpose, a method of controlling the plasma distribution to make the beam distribution uniform has been considered. For example, in general research, the plasma distribution has been controlled by a magnetic field. Plasma distribution control has the advantage that the distribution can be adjusted during the process without opening the vacuum vessel.

In order to compensate for the difficulty in controlling the plasma distribution of the ion source, as a second method, the change in the beam distribution due to the extraction electrode system is used, and the non-uniformity of the plasma distribution is determined by the geometric parameters of the electrodes. Complementary methods to improve beam uniformity have often been used. That is,
There are a method of changing the interval between the extraction electrodes at the center and the periphery using a spacer or the like, and a method of changing the hole density of the electrode between the center and the periphery as disclosed in Japanese Patent Application Laid-Open No. 8-129998.

As a third method, there is a method of shaping the ion beam itself by using a magnetic lens or the like, which has been used for a small-diameter beam.

[0007]

Among the above three prior arts, the first and second methods are actually employed in a large-diameter ion source. The third method is
A large-diameter beam requires a huge electromagnet, is not realistic and has not been adopted. Here, we consider the first and second methods.

In the first method, the plasma distribution control using a magnetic field, the distribution can be adjusted during the operation.
It is difficult to control over a wide range and adjust to a desired distribution from the complicated mechanism of phenomena, and it lacks practicality. Moreover, it is difficult to guarantee reproducibility.

In the second method, the production of the extraction electrode is considerably expensive, and it is not clear whether the target uniformity can be obtained at one time. Requires time and huge costs. In any case, when the extraction electrode system is modified, the ion beam processing apparatus must be opened to the atmosphere, which causes a large time loss for the processing apparatus. Also, depending on the processing process,
Since a high-current ion beam or a low-current ion beam is used, the distribution of the plasma and the electrode spacing changes due to the difference in the power applied to the ion source, and the uniformity of ion beam processing may be impaired. . Due to such a property, when the adjustment by the beam extraction system changes the operating condition, that is, when the plasma distribution changes, it is impossible to correct the distribution during operation.

An object of the present invention is to provide an ion beam capable of easily controlling the distribution of the extracted ion beam even during the process without depending on the adjustment of the extraction electrode, and obtaining a uniform ion beam or an ion beam having a desired distribution. It is to provide a distribution control method and an ion beam processing device.

[0011]

In order to achieve the above object, the present invention provides a method for controlling the distribution of an extracted ion beam by electrically controlling the plasma distribution in an ion source to obtain a uniform ion beam or a desired distribution. Is obtained.

That is, according to the present invention, a plasma is generated by an ion source, an ion beam is extracted from the plasma by an extraction electrode, and the extracted ion beam is irradiated on a substrate or a target, and the substrate or the target is irradiated with the ion beam. In performing the ion beam processing, the ion beam distribution on the substrate or the target is controlled by manipulating the plasma distribution or the ion current distribution in the ion source.

As a specific method for operating the plasma distribution or the ion current distribution in the ion source, the present invention provides:
A plurality of electrodes are provided inside the ion source facing the plasma, and a magnetic field having lines of magnetic force intersecting the current path between the electrodes is applied supplementarily, and the plasma distribution or the ion current distribution is generated by the electric field generated between the electrodes. Is operated.

The present invention also provides an ion source having an extraction electrode for generating a plasma and extracting an ion beam from the plasma, a substrate or a target, and applying the ion beam extracted by the extraction electrode to the substrate or the target. An ion beam processing apparatus having a processing chamber for irradiating the substrate or target with an ion beam, wherein the ion source has a magnetic field having a component perpendicular to the extraction electrode therein, The electrodes are installed either as the center of the surface facing the extraction electrode and the side wall itself of the ion source, or inside the ion source, and the potential of each electrode is independently controlled from the extraction electrode, and the magnitude relationship between them is arbitrarily operated. And a potential operating means capable of performing the operation. In addition,
The present invention is also applicable to an ion beam processing apparatus that generates plasma by high frequency or microwave.

Further, according to the present invention, a spirally wound coil antenna is provided on the outer peripheral surface of a container, and plasma is generated in the container by supplying high frequency power to the coil antenna, and an ion beam is generated from the plasma. An ion source having an extraction electrode to be extracted, and a processing chamber for holding a substrate or a target, irradiating the substrate or target with an ion beam extracted by the extraction electrode, and performing ion beam processing on the substrate or the target. In the ion beam processing apparatus, the ion source forms a magnetic field having a component perpendicular to the extraction electrode inside the ion source,
Inside the ion source, electrodes are respectively installed along the center of the surface facing the extraction electrode, and along the inner periphery of the ion source. Of the two electrodes, the electrode installed along the inner periphery of the ion source is a coil antenna. Is formed of a cylindrical electrode with a slit along the axial direction of the electrode, or a strip-shaped electrode extending in the axial direction of the coil antenna, and the potential of each electrode is arbitrarily controlled independently of the extraction electrode. And a potential operating means that can perform the operation.

Further, according to the present invention, a coil antenna wound in a plane spiral is provided on the upper surface of a container, and plasma is generated in the container by supplying high frequency power to the coil antenna, and an ion beam is generated from the plasma. An ion source having an extraction electrode to be extracted, and a processing chamber for holding a substrate or a target, irradiating the substrate or target with an ion beam extracted by the extraction electrode, and performing ion beam processing on the substrate or the target. In the ion beam processing apparatus, the ion source has a magnetic field having a component perpendicular to the extraction electrode inside the container, and the side wall of the container forms an electrode, and the electrode is installed at the center of the surface facing the extraction electrode inside the ion source, In addition, the potentials on the side wall of the container and the electrodes can be controlled independently of the size of the electrodes independently of the extraction electrodes. It is characterized in that a potential operation means capable.

Further, according to the present invention, it is possible to provide a measuring means for measuring the distribution state of the ion beam, and a control means for controlling the potential adjustment amount of the potential adjusting means based on the measurement result from the measuring means.

Here, the principle of the present invention will be described with reference to FIG. In FIG. 1, (a) illustrates the movement of magnetic field lines and electrons, which is the basis of the electric field control of the present invention, and (b)
Is the resulting potential distribution in the plasma.
(C) shows the potential distribution and the movement of ions in the AA 'section, and (d) shows the ion current distribution, that is, the shape of the extraction beam distribution in the AA' section. Since the present invention achieves this by controlling the plasma distribution in the ion source when controlling the ion beam of the ion beam processing apparatus as shown in FIG. 15, FIG. 1 shows only the ion source section. . For convenience of explanation, a spiral RF antenna 29 is used as the ion source.
An inductively coupled ion source that generates a plasma 50 is used. The RF antenna 29 is for generating a plasma 50, not for generating a magnetic field. Note that, if the principle can be applied, it does not depend on the plasma generation method of the ion source.

The required configuration of the present invention is as follows. Assuming that the direction perpendicular to the beam extraction surface of the ion source is the axial direction and the ion source is a columnar shape extending in the axial direction, as shown in FIG. An ion source 1 having a magnetic field having an axial component
The ion source 1 is located in the center of the surface facing the extraction electrode 20.
Is provided, and a cylindrical electrode 27 is also provided on the inner periphery of the side wall of the ion source 1. If arranged on the circumference, the electrode 27 may be the housing of the ion source 1. These electrodes 26 and 27 are referred to as plasma distribution control electrodes A and B, respectively. However, the electrodes 26,
27 are required to be insulated from the extraction electrode 20a and to be able to independently control the potential. The electrode 26 is desirably a small plate or a rod extending on the center axis.

Next, a method of controlling the distribution of the plasma 50 will be described. According to the present invention, a radial potential gradient, that is, an electric field is generated in the ion source plasma 50 by the above configuration, and the movement of ions can be controlled in the radial direction. As a result, the distribution of the extracted ion current changes. Things. The distribution control is essentially different from the magnetic field control that controls the movement of electrons to change the plasma distribution in that the distribution is controlled by the movement of ions using a potential gradient or an electric field for the distribution control. Although a magnetic field having an axial component is used to generate a potential gradient in the plasma 50, it is only used in principle in an auxiliary manner, and variability of the magnetic field is not necessarily required as a distribution control method. Regarding the electric field control of the distribution, more essentially the required magnetic field is a magnetic field having lines of magnetic force that intersect the current path connecting the electrodes 26, 27,
An electric field is generated mainly in the direction perpendicular to the magnetic field lines. In the ion source 1, a magnetic field having an axial component is used in order to generate an electric field in the radial direction.

In a plasma without a magnetic field, the potential distribution in the plasma usually becomes the same in most of the plasma except for the wall sheath portion as shown in (1) to (3) of FIG. In this state, ions move almost isotropically. Here, when a magnetic field is applied in the axial direction as shown in FIG. 1 (a) and a potential difference is applied between the central electrode 26 and the peripheral electrode 27, the movement of electrons is restricted by this magnetic field, and the radius is equivalently increased. The electrical resistance in the direction increases, and the potential distribution in the plasma is shown in FIG.
As shown in (4) and (5) of FIG. 1 (c), a radial potential gradient, that is, an electric field is generated in the plasma. The ions in the plasma move in the radial direction due to this electric field, and the distribution of the plasma changes. When the inner electrode 26 is set to a high potential and the peripheral electrode 27 is set to a low potential in FIG. 1 (4), the potential distribution becomes a convex distribution bulging at the center, and the ions are distributed outward in the radial direction. Move toward As a result, as shown in (4) of FIG. 1D, a high concave ion current distribution in the peripheral portion is obtained. Conversely, when the condition as in (5), that is, when the inner electrode 26 is set to a low potential and the peripheral electrode 27 is set to a high potential, the potential distribution becomes a concave distribution which is concave at the center, and the ions gather toward the center. . As a result, a highly convex ion current distribution at the center as shown in (5) of FIG. 1D is obtained.

For reference, when the potential of the plasma distribution control electrodes 26 and 27 is changed without a magnetic field, FIG.
As shown in the distributions (1) to (3) of (c), the potential is almost constant in the plasma, the slope is formed only at the sheath portion at the end, and the potential only increases and decreases according to the magnitude of the voltage. In this state, since ions move isotropically, distribution control cannot be performed.

As described above, with the change in the potential distribution, the distribution of ions in the plasma 50 changes, and the distribution of the ion beam extracted from the extraction electrode 20 changes. It is possible to control the beam distribution. Since the extraction current is increased when extracting ions, it is desirable to apply a positive bias potential to the extraction source electrode 20a to the ion source housing or to an electrode in the ion source. Therefore, both the plasma control electrodes 26 and 27 or Either one has a potential higher than at least the extraction electrode 20a. The potential of the plasma control electrodes 26 and 27 does not necessarily need to be higher than the potential of the extraction electrode 20a, but it is desirable that the extraction electrode 20a has the lowest potential in the ion source.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) An ion milling apparatus will be described as an example of an ion beam processing apparatus according to the present invention. FIG.
Is a cross-sectional view of the ion milling apparatus, and FIG. 4 is a cross-sectional view of an ion source part of the ion milling apparatus. An ion milling device is used, for example, in the process of manufacturing a thin-film magnetic head.
In addition to an alumina film, a magnetic film forming a magnetic core, and a copper film forming a coil, a gold film, a chromium film, an Altic substrate, and various resists are etched by an ion beam. The ion milling apparatus includes an ion source 1, an extraction electrode 20 having a number of holes for extracting Ar ions (Ar ⁺ ) in an Ar plasma 50 in the ion source 1 as an ion beam, and a substrate to be processed. And a processing chamber 7 for milling the surface of the substrate 40 with an ion beam.
The ion source 1 is connected to the processing chamber 7, and the ion source 1 and the processing chamber 7 constitute a vacuum chamber. An exhaust port 6 is provided in the processing chamber 7, and a gas in the ion source 1 and the processing chamber 7 is evacuated from the exhaust port 6 by a vacuum pump (not shown).

As shown in FIG. 4, in the ion source 1, a coil antenna 29 is spirally wound around the body 2 of the ion source housing. A plasma 50 is generated inside the source 1. The coil antenna 29 is connected to an RF power supply 32 via a matching unit 38, and the coil antenna 29 is supplied with RF power having a frequency of about 2 MHz. Ion source body 2
Is made of a quartz tube having an outer diameter of 300 mm, a length of 200 mm, and a thickness of 5 mm. The upper part is fixed by an upper flange 1a made of SUS, and the lower part is fixed by a lower accelerating flange 4. Support flange 2 on lower acceleration flange 4
4 is fixed, and the extraction electrode 2 is
0 is attached.

As shown in FIG. 2, the plasma container constituted by the body 2 of the ion source housing is accommodated in the outer wall 1b of the ion source. 4 is fixed. The outer wall 7a of the processing chamber is also fixed to the lower acceleration flange 4 via the insulator 5. An exhaust hole 10 is formed through the lower accelerating flange 4 and the insulators 3 and 5 above and below the lower accelerator flange 4, and a space between the ion source housing body 2 and the ion source outer wall 1 b is formed through the exhaust hole 10. Is evacuated. This allows
Since the plasma container formed by the ion source housing body 2 is in a vacuum, the ion source housing body 2 does not need to have a structure that can withstand atmospheric pressure, and should be formed of a thin quartz tube. Can be. The outer wall 1b of the ion source is made of SUS.
Since the upper flange 1a is also made of SUS, the periphery of the ion source 1 is surrounded by stainless steel, so that leakage of electromagnetic waves from the coil antenna 29 can be minimized.

The upper flange 1a is provided with a plasma generating gas inlet 8, and a plasma generating gas, for example, Ar gas is introduced into the ion source 1 from the plasma generating gas inlet 8. A gas diffuser 9 made of aluminum is fixed to the lower surface side of the upper flange 1a while being insulated from the upper flange 1a, and Ar gas introduced from the plasma generating gas inlet 8 is diffused to the peripheral portion by the gas diffuser 9. I do.

In the vicinity of the coil antenna 29, electrons heated by the induced electric field generated inside the body 2 of the ion source housing collide with the gas introduced and diffused from the gas inlet tube 8, and generate plasma 50. Generated plasma 50
Are spread uniformly in the plasma chamber by diffusion. On the lower surface side of the gas diffuser 9, a plasma distribution control electrode A26 is provided via an insulating spacer. A plasma distribution control electrode B27 is provided on the inner periphery of the body 2 of the ion source housing. As shown in FIG. 3, the plasma distribution control electrode B27 has a cylindrical shape, and a plurality of slits 27a are formed in the cylindrical surface along the axial direction. The slit 27a is provided to prevent the coil antenna 29 and the plasma distribution control electrode B27 from being coupled to each other so that a circumferentially induced current flows through the electrode and the plasma generation power is lost. These electrodes 26 and 27 can independently apply a positive or negative potential to the extraction electrode 20. This potential has the effect of defining the potential of the plasma and making it easier for ions to flow to the extraction electrode 20. An external coil 18 for generating a magnetic field is installed on the upper outside of the ion source 1, and a magnetic field having an axial component of about 10 to 100 Gauss is generated inside the plasma chamber.

The plasma distribution control electrode A26 is connected to a power source 36.
Further, the plasma distribution control electrode B27 is connected to a power supply 37, and the voltage applied to the plasma distribution control electrode A26 or the plasma distribution control electrode B27 can be controlled by the power supplies 36 and 37.

Extraction electrode 2 provided below ion source 1
0 is composed of three electrode plates 20a, 20b, 20c,
An electrode plate 20a is arranged on the side closer to the ion source 1, an electrode plate 20c is arranged on the side closer to the processing chamber 7, and an electrode plate 20b is arranged in the middle. These three electrode plates are made of a conductor having a thickness of 1 mm, and a plurality of holes are formed over the entire ion extraction region having a diameter of 200 mm. The positions of the plurality of holes are all formed at the same position, and ions are extracted through these holes. As the material of the electrode plate, molybdenum is preferable because of its high melting point, high thermal conductivity, and low thermal expansion coefficient. These three electrode plates are electrically insulated by an insulating spacer 25 while supporting the support flange 24.
Fixed to.

The potential of the electrode plate 20a is supplied by a power supply 35 via the acceleration flange 4 and the support flange 24. 600 to 100 is applied to the electrode 20a on the side closer to the ion source.
A high voltage of about 0 V is applied to the lower electrode 20b by −30.
A negative voltage of about 0 V is applied from a power supply (not shown). The electrode 20c closer to the processing chamber 7 is
And is kept at the same ground potential. The ions extracted from the plasma 50 are accelerated by the electric field formed between the extraction electrodes 20a to 20c by these voltages. Since a high voltage is applied to the lower acceleration flange 4, insulating spacers 3 and 5 are provided between the ion source 1 and the processing chamber 7.

In the processing chamber 7, a substrate 40 as an object to be processed is provided.
Is provided, and a tungsten filament 13 for neutralizing electron emission for neutralizing the extracted ion beam is provided to prevent a reduction in milling amount and device damage due to charging of the substrate 40. .
The tungsten filament 13 is connected to a power source (not shown). Note that the substrate holder 41 can support and rotate the substrate 40 at an angle to the ion beam. The processing chamber 7 and the substrate holder 41 are both at the ground potential.

Next, the operation of the ion beam processing apparatus having the above configuration will be described. First, a case where two plasma distribution control electrodes 26 and 27 are not provided in the ion source and no magnetic field is formed in the ion source will be described. Normally, as shown in FIG. 4, the generation of plasma by the coil antenna 29 occurs strongly in the outer peripheral portion of the ion source, and the radial distribution of the plasma in the portion where the coil antenna 29 is wound is such that the plasma is concave at the center and the outer peripheral portion is high Becomes However, this is a case where the gas pressure in the ion source is relatively high such as 1 Pa or more. Since the gas pressure used in the ion source is usually about several tens mPa,
The plasma diffusion effect is significant, resulting in a somewhat flat or high plasma distribution at the center. Further, the extraction electrode 2
Since the vicinity of 0 is distant from the coil antenna 29, the diffusion effect further acts, and the distribution becomes high at the center. The plasma potential is substantially constant spatially in the ion source except for the sheath portion, and is several tens of volts higher than the potential of the extraction electrode 20. Due to the plasma potential, the ions flow naturally toward the extraction electrode 20 and are extracted from the electrode hole. In this type of ion source, the extraction electrode 20 also serves as an electron collecting electrode at the same time, so that ion beam extraction can be achieved without applying a bias voltage normally used for the conductor housing of the ion source. By applying a positive potential to the extraction electrode 20 to make the plasma potential higher than in the previous state, more ions can be extracted. In the present embodiment, it is basically assumed that such a bias voltage is applied to the plasma.

Next, the plasma distribution control method and the roles of the bias electrode, the plasma distribution control electrode and the axial magnetic field in this embodiment will be described.

Since the ion source extracts ions,
The ability to manipulate the movement and distribution of ions is easy to understand and control as a phenomenon. However, conventional methods of controlling plasma distribution are generally based on magnetic fields, such as those that increase the uniformity by confining the plasma with a cusp magnetic field or a mirror magnetic field, and those that change the plasma generation position. Only had an effect. Therefore, the phenomenon of magnetized plasma is very complicated, and it is not the kind that the distribution changes in a certain direction simply by increasing the magnetic field. Since ions to be extracted have a larger mass than electrons, they cannot exert an effect in a magnetic field in a normally used range, and it is difficult to control ions only by a magnetic field.

On the other hand, in the present embodiment, the distribution of plasma is controlled by an electric field, mainly for ions. Due to its nature in plasma, even if an electrode is applied to apply a potential difference, a potential gradient, that is, an electric field generally does not occur except for the sheath portion. This is because the movement of electrons, which is the main current medium in the plasma, is restricted by the magnetic field, and the electric resistance value equivalently increases. This electric field moves ions that are less likely to be constrained by the magnetic field, and produces a kind of polarization state that cancels out the electric field.

In the present embodiment, a magnetic field is used, but is merely an auxiliary for generating an electric field, and in principle, it is not actively varied to control the distribution. Plasma distribution control electrode A2 installed at the upper center of the ion source
6 and a plasma distribution control electrode B27 installed on the inner circumference
A magnetic field having an axial component is generated by a magnetic field generating coil between the electrodes, and a potential difference is generated between the electrodes 26 and 27 to generate a potential gradient in the radial direction. The distribution of the ion current can be changed. By changing the potential relationship between the two electrodes 26 and 27, it is possible to change from a convex type to a concave type. For example, if the electrode on the relatively inner side is positive and the electrode on the circumference is negative, the ions are polarized outward in the radial direction, and the distribution of the ions has a concave or outer height distribution in a radial cross section. By reversing the potential relationship, a convex shape, that is, an inner height distribution can be obtained. However, it is desirable that at least one of the two electrodes 26 and 27 has the same or higher potential as the extraction electrode. This is because, of the three electrodes 20a, 26, and 27 in contact with the plasma surface, the extraction electrode 2
When Oa has the highest potential in the ion source, most of the ions are at other electrodes, that is, the plasma distribution control electrodes 26 and 27.
This makes it easier for the ions to flow, and the extraction of ions is not performed efficiently. The electrode with the highest potential in the ion source substantially affects the potential of the plasma and becomes the bias potential.
By performing these operations at a potential position higher than the potential of the extraction electrode 20a, distribution control can be effectively performed.
However, there may be a case where the potential is lower than the potential of the extraction electrode 20a, giving priority to the distribution control.

FIG. 5 shows an example of a change in the distribution of the ion current at the position of the extraction electrode in the ion source plasma in the present embodiment. When the internal pressure of the ion source is constant at 57 mPa, the extraction current amounts are made equal, and V1: Low, V2:
The results for High and vice versa are shown. V1: L
In the case of ow, in the case of V2: High, the ions are shifted to the center, so that the distribution near the center has a high convex shape. Conversely, V1: Hi
gh, V2: In the case of Low, ions decrease at the center,
Since it gathers in the periphery, it has a concave distribution with a low center. The fact that the ion current is attenuated at a radius of 60 mm or more is due to wall loss to the inner wall of the ion source and is unique to the ion source. If a cusp magnetic field or the like is used in combination with this ion source, such a decrease in the density of the peripheral portion can be suppressed to a low level. The density is higher in the convex type as a whole, because the amount of the drawn current represented by the integral of the density distribution is made uniform. This distribution can be freely changed up and down by increasing or decreasing the RF power for plasma generation.

The distribution of the extracted ion beam is slightly different from the ion current distribution in the ion source, but the change tendency is the same. Assuming that the ion current distribution in the ion source is flat, the extraction beam distribution slightly expands or dents at the center,
It is unlikely to have a wavy and complex distribution. Therefore, by giving such an unevenness controllability to the ion current distribution in the ion source, the extracted ion beam also has the same controllability, and a uniform beam can be obtained. Of course, distribution changes due to the beam extraction system can be compensated. In the case of this example, if the substrate is a 4-inch (φ100) substrate, a sufficient distribution control effect can be obtained. As described above, the distribution of the extracted ion current can be controlled from the convex type to the concave type by the auxiliary magnetic field having the axial component and the potential operation of the electrodes on the center and the periphery. When this control method was actually applied to make the ion beam distribution uniform, the uniformity was ± 3.7% to ± 1.7% in the range of a 4-inch substrate (φ100).
It was possible to homogenize up to 7%.

(Embodiment 2) Next, Embodiment 2 of the present invention will be described. In the present embodiment, as shown in FIG. 6, two external coils for generating a magnetic field are arranged on a concentric circle, and the respective coil currents are adjusted.
Further, the shape of the unevenness of the distribution is changed. As an external coil for generating a magnetic field, a magnetic field generating coil 18 is arranged on the outside and a magnetic field generating coil 19 is arranged on the inside. When a coil current flows in the same direction in both coils 18 and 19, the generated magnetic field is The magnetic flux density increases at the center of the ion source.

As shown in FIG. 7, a magnetic field generating coil 18 is disposed outside and a magnetic field generating coil 19 is disposed inside.
When coil currents flow in opposite directions to both coils 18 and 19, the generated magnetic field has a low magnetic flux density at the center of the ion source.
Higher in the periphery.

Since the potential gradient generated in the plasma increases as the magnetic flux density increases, as a result, as shown in FIG. 8, the ion current distribution has a mountain shape in FIG. 6 and a trapezoidal shape in FIG. Becomes That is, it is possible to control not only the unevenness of the distribution but also the shape.

If it is not desired to use a large magnetic field generating coil as described above, or if it is not necessary to operate up to the uneven shape, as shown in FIG. A similar effect can be obtained by providing a lateral magnetic field in the body 2 to generate an appropriate axial magnetic field.

Third Embodiment Next, a third embodiment of the present invention will be described. In the present embodiment, as shown in FIG. 10, a shutter 42 is provided above the substrate holder 41, and the shutter 42
And a Faraday cup 43 for measuring a beam distribution above the shutter 42. Before the substrate processing, the Faraday cup 43 is swept in the processing chamber 7 to measure the distribution state of the ion beam.
The measurement result is sent to the arithmetic unit 70. The arithmetic unit 70 supplies the power source 36 based on the measurement result from the Faraday cup 43.
37, the voltage applied to the plasma distribution control electrode A26 and the plasma distribution control electrode B27 is automatically adjusted. As a result, the ion beam is controlled to an optimal distribution, and as a result, a change in the beam extraction system due to thermal deformation and a change in the beam distribution due to a change in process parameters can be compensated.

(Embodiment 4) Next, Embodiment 4 of the present invention will be described. In the present embodiment, a planar spiral coil antenna 29a is provided above the ion source 1 as shown in FIG. The upper portion of the ion source 1 is formed of an upper quartz plate 2a made of quartz, and the plasma distribution control electrode A26 'is formed below the upper quartz plate 2a in the ion source 1.
Is provided. A plasma distribution control electrode B27 'is provided on the side of the ion source 1, and the plasma distribution control electrode B27' also serves as an ion source chamber. The plasma distribution control electrode B27 'has a cylindrical shape, and no slit is formed in the cylindrical surface. As shown in FIG. 12, the plasma distribution control electrode A26 'has a plurality of slits 26a formed in the radial direction. With such a configuration, the same operation and effect as those of the first embodiment can be obtained.

Coil antenna 29 as in the first embodiment
In the case of an inductively coupled ion source or the like that generates plasma by using an ion source, the ion source housing body 2 made of quartz may be constituted by the plasma distribution control electrode B27 itself in applying the present invention. Generally, in an inductively coupled ion source, in order to improve the coupling between the coil and the plasma,
The plasma is generated in a chamber made of a dielectric, for example quartz. In a metal-walled chamber that covers the entire plasma, energy from the antenna is lost as induced current in the chamber wall and no plasma is generated. In order to avoid an induced current in the circumferential direction, it is necessary to provide a chamber wall provided with a slit or the like in the axial direction. Such an inductively coupled ion source in a metal housing has been around for a long time and is not impossible. This shape corresponds to the plasma distribution control electrode B2 in the present embodiment.
Since the ion source housing body 2 is insulated from the acceleration flange 4 and the upper flange 1a because it has the same shape as that of
The plasma distribution control electrode B27 itself can be used as the body of the ion source housing. Leakage of gas from the slits can be reduced by reducing the slit width, wrapping the periphery with a two-tiered slit electrode that makes the slit invisible, a Teflon (registered trademark) sheet that is much cheaper than quartz, etc. It can be suppressed as much as possible. In some cases, gas leaks may not be as problematic.

The fact that the ion source can be formed in the metal chamber means that the influence of conductive deposits on the inner wall of quartz that determines the maintenance cycle of the inductively coupled ion source can be avoided, and the life of the ion source can be extended. Can be planned. The maintenance cycle becomes longer, the production efficiency increases, and expensive maintenance costs such as cleaning and replacement of quartz are eliminated. In addition, with respect to the insulating deposit, the performance of the ion source is not affected because the chamber is originally formed of a dielectric material, that is, an insulating material. However, there is a decline in the role as an electrode. This can be prevented by performing ion sputter cleaning by setting the potential of the plasma distribution control power supply B27 to 0 or negative with respect to the potential of the extraction electrode 20a as needed. Further, if the chamber is a metal chamber, it is possible to provide a cooling means such as water cooling or gas cooling because of its good thermal conductivity. Can be managed. When a reactive gas is used, the insulating deposits can be removed under such appropriate temperature control. Conversely, when the temperature is insufficient, a heater can be used unlike quartz. By increasing the slit interval, instead of reducing the input power to the plasma, the electrode can be heated using partial energy for induction heating of the electrode. The present invention is suitable for application to an inductively coupled ion source of a metal chamber having many advantages as described above.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described. In this embodiment, as shown in FIG. 13, a microwave ion source is used as an ion source system using an ion beam distribution control method. Although the configurations of the power supply and the electrodes are the same as those in the first embodiment, in this embodiment, the microwave is introduced from the upper portion of the ion source through the waveguide 30, so that the upper surface of the ion source 1 is made of quartz. It is formed of the upper quartz plate 2a. And
A plasma control electrode A26 is provided at the lower center of the upper quartz plate 2a in the ion source 1. A side portion of the ion source 1 is a plasma distribution control electrode B27 'made of metal.
The plasma distribution control electrode B27 'also functions as an ion source chamber.

In the above configuration, an axial magnetic field of 875 gauss for generating microwaves of 2.45 GHz and electron cyclotron resonance is generated in the ion source 1 by the external magnetic field coil 17. The plasma is efficiently generated by electron cyclotron resonance with microwaves introduced from above and is confined by a magnetic field.
This magnetic field also plays an auxiliary role as a plasma distribution control method.

According to the present embodiment, an ion beam distribution control similar to that of the first embodiment can be performed by the plasma distribution control electrodes 26 and 27 'having the auxiliary magnetic field in the axial direction. The upper flange 2 is made of quartz plate 2
Therefore, it is not necessary to interpose a spacer between the ion source housing and the ion source housing. This electrode 26 can also serve as the plasma generating gas inlet 8 at the same time.

As an ion source having a magnetic field and an electrode structure similar to the present invention, a kaufman type ion source as shown in FIG. However, the electrode (anode 21) on the periphery of the kaufman type ion source is necessary for maintaining the discharge, and cannot be set at a negative potential with respect to the central electron source (filament 12). This is because plasma cannot be generated and maintained. In addition, the potential of the upper portion of the ion source is the same as the potential of the extraction electrode 20, and is not independent of the potential of the extraction electrode. Therefore, in the kaufman type ion source, it is possible to control the distribution of ions to be convex, but not to control the distribution of ions to be concave. The structure of the present invention can be applied to any ion source, such as an inductively-coupled ion source or a microwave ion source as in the above embodiment, as long as the plasma generation mechanism does not depend on the central and peripheral electrodes. It is possible.

[0052]

As described above, according to the present invention,
Even if a vacuum chamber such as an ion source or a processing chamber is opened to adjust electrodes or the like, a uniform or desired ion beam distribution can be easily obtained by control by an external electric means.

In addition, the plasma distribution and the ion beam distribution that change depending on the process conditions such as the ion source input power and the gas flow rate can be corrected on-time, and high-quality ion beam processing can be performed.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams for explaining the principle of the present invention, in which FIG. 1A shows the movement of lines of magnetic force and electrons, FIG. 1B shows the potential distribution in plasma, and FIG. 1C shows AA ′ in FIG. It is the figure which showed the potential distribution of a cross section and the movement of ion, and (d) which showed the ion saturation current distribution of the AA 'cross section of (a), respectively.

FIG. 2 is a sectional view of the ion beam processing apparatus according to the first embodiment.

FIG. 3 is a perspective view of a plasma distribution control electrode B installed on an inner periphery of an ion source.

FIG. 4 is a sectional view of an ion source provided in the ion beam processing apparatus of FIG. 2;

FIG. 5 is a diagram showing a measurement result of an ion current density on an extraction electrode surface.

FIG. 6 is a cross-sectional view of the ion source unit according to the second embodiment, showing a state when a coil current is applied to coils 18 and 19 in the same direction.

FIG. 7 is a cross-sectional view of the ion source unit according to the second embodiment, showing a state when a coil current is applied to coils 18 and 19 in opposite directions.

8 is a diagram showing a change in ion current distribution in FIGS. 6 and 7. FIG.

FIG. 9 is a cross-sectional view of an ion source in which a magnetic field is formed by permanent magnets on the side of the body.

FIG. 10 is a sectional view of an ion beam processing apparatus according to a third embodiment.

FIG. 11 is a cross-sectional view of an ion source according to a fourth embodiment, illustrating a type of ion source having a spiral coil antenna at an upper portion.

12 is a perspective view of a plasma distribution control electrode A installed inside the ion source shown in FIG.

FIG. 13 is a sectional view of an ion beam processing apparatus according to a fifth embodiment.

FIG. 14 is a sectional view of an ion beam processing apparatus using a Kaofman type ion source.

FIG. 15 is a sectional view of an ion beam processing apparatus using a bucket type ion source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ion source 1a Upper flange 2 Ion source body 2a Upper quartz plate 3,5 Insulator 6 Exhaust port 7 Processing chamber 7a Outer wall 8 Plasma generation gas inlet 9 Gas diffuser 10 Exhaust hole 11 Permanent magnet 12 For arc discharge Filament 13 Neutralized electron emission filament 14 Cooling tube 15 Permanent magnet 16 Yoke 17, 18, 19 External coil for generating magnetic field 20, 20a-20c Ion extraction electrode 21 Anode 24 Electrode support flange 25 Spacer 26, 26 'Plasma distribution control electrode A 27, 27 'Plasma distribution control electrode B 28 Spacer 29 Spiral coil antenna 29a Planar spiral coil antenna 30 Waveguide 31 Power supply for thermionic emission filament 32 RF power supply 33 Arc power supply 34 Bias resistor 35 Acceleration power supply 36 Plasma distribution control power supply A 37 Plus Distribution control power B 38 matching device 40 substrate (or target) 41 substrate holder 42 the shutter 43 Faraday cup 50 plasma 52 ion beam 70 calculator

Claims (7)

[Claims] A plasma is generated by an ion source, an ion beam is extracted from the plasma by an extraction electrode, and the extracted ion beam is irradiated on a substrate or a target to perform ion beam processing on the substrate or the target. An ion beam distribution control method, comprising: controlling a plasma distribution or an ion current distribution in the ion source to control an ion beam distribution on the substrate or the target. 2. The ion beam distribution control method according to claim 1, wherein a plurality of electrodes are provided inside the ion source facing the plasma, and a magnetic field having magnetic lines of force intersecting a current path between the electrodes is provided. An ion beam distribution control method in which a plasma distribution or an ion current distribution is supplementarily applied to control a plasma distribution or an ion current distribution by an electric field generated between the electrodes. 3. An apparatus for generating plasma and holding an ion source having an extraction electrode for extracting an ion beam from the plasma, a substrate or a target, and irradiating the substrate or target with the ion beam extracted by the extraction electrode. A processing chamber for performing ion beam processing on a substrate or a target, and wherein the ion source has a magnetic field having a component perpendicular to the extraction electrode therein, and the ion source An electrode is installed inside or inside the center of the surface facing the extraction electrode and the side wall itself of the ion source, and the potential of each electrode is independent of the extraction electrode, and is larger or smaller than the extraction electrode. Ion beam characterized by providing potential operating means capable of arbitrarily operating the relationship. Processing apparatus. 4. An ion source having an extraction electrode for generating a plasma by high frequency or microwaves and extracting an ion beam from the plasma, and a substrate or a target, and holding the ion beam extracted by the extraction electrode on the substrate or the substrate. A processing chamber for irradiating the target or performing ion beam processing on the substrate or the target, wherein the ion source has a magnetic field having a component perpendicular to the extraction electrode inside the ion source. Inside the ion source, the center facing the extraction electrode, and the side wall itself of the ion source, or each electrode is installed inside the ion source, and the potential of each electrode is independent of the extraction electrode And potential control means for arbitrarily controlling each magnitude relation. Ion beam processing apparatus, characterized in that the. 5. A coil antenna wound spirally is provided on an outer peripheral surface of the container, and a high-frequency power is supplied to the coil antenna to generate plasma in the container and to provide an extraction electrode for extracting an ion beam from the plasma. Holding an ion source and a substrate or target,
A processing chamber for irradiating the substrate or target with the ion beam extracted by the extraction electrode and performing ion beam processing on the substrate or target, wherein the ion source has the ion source therein. A magnetic field having a component perpendicular to the extraction electrode is formed, and an electrode is provided inside the ion source along the center of the surface facing the extraction electrode, and along the inner circumference of the ion source. The electrode installed along the inner periphery of the ion source is formed of a cylindrical electrode having a slit along the axial direction of the coil antenna, or a strip-shaped electrode extending in the axial direction of the coil antenna, The potential of each electrode is provided with potential operation means capable of arbitrarily operating the magnitude relationship independently of the extraction electrode. An ion beam processing apparatus characterized by the above-mentioned. 6. A coil antenna wound in a plane spiral shape is provided on the upper surface of the container, and a high-frequency power is supplied to the coil antenna to generate plasma in the container, and an extraction electrode for extracting an ion beam from the plasma. Holding an ion source and a substrate or target,
A processing chamber for irradiating the substrate or target with the ion beam extracted by the extraction electrode and performing ion beam processing on the substrate or target, wherein the ion source has the ion source therein. Having a magnetic field having a component perpendicular to the extraction electrode, the container side wall forms an electrode,
An electrode is installed in the center of the surface facing the extraction electrode inside the ion source, and the potential of the container side wall and the electrode can be arbitrarily manipulated in magnitude relation independently of the extraction electrode. An ion beam processing apparatus comprising a potential operating means. 7. The ion beam processing apparatus according to claim 3, further comprising a measuring unit for measuring a distribution state of the ion beam, and the potential adjusting unit based on a measurement result from the measuring unit. An ion beam processing apparatus provided with control means for controlling a potential adjustment amount of the ion beam.