JP5004318B2 - Ion implanter - Google Patents

Description

  The present invention relates to an ion implantation apparatus, and more particularly to an improvement of an ion implantation apparatus that enables high-precision parallelization of ion beams in two directions.

Various types of ion implantation apparatuses for accelerating ions from an ion source to a desired energy and implanting the ions on a solid surface such as a semiconductor have been put to practical use (see Patent Documents 1 to 4).
Hereinafter, an example of the entire configuration of a conventional ion implantation apparatus will be described with reference to FIG.
FIG. 8 is a plan view showing a schematic configuration of a conventional ion implantation apparatus.

As shown in FIG. 8, the main configuration of the ion implantation apparatus 100 is an ion source 110, a mass separator 120, a mass separation slit 130, an acceleration tube 140, a quadrupole lens 150, a scanner 160, and a collimator 170. .
In the figure, reference numeral 180 denotes a semiconductor device substrate serving as a target for implanting ions arranged at an end station (not shown), and may be simply referred to as “substrate” hereinafter.
B is an ion implanted into the substrate 180 and may be referred to as an “ion beam” or “beam” hereinafter.

The ion source 110 is an apparatus that generates ions by stripping electrons from atoms and molecules.
The mass separator 120 generates a magnetic field and / or an electric field by utilizing the property that charged particles such as ions and electrons are deflected in the magnetic field or electric field, and the ion species to be injected into the substrate 180. It is a device for specifying.

  The acceleration tube 140 is a device for accelerating or decelerating a desired ion species that has passed through the mass separation slit 130, but as shown in FIG. A high voltage equal to the electrode pair is applied, and the ion beam B is accelerated or decelerated to a desired implantation energy by the action of an electrostatic field.

The scanner 160 generates a uniform external electric field in a direction orthogonal to the traveling direction of the ion beam B, and controls the ion deflection angle by changing the polarity and intensity of the electric field, as shown in FIG. Then, the ions B are scanned at a desired position on the implantation surface of the substrate 180 and uniformly implanted.
Further, in FIG. 8, a pair of electrodes of the scanner 160 that deflects the ion beam B in the horizontal direction is shown for simplification, but this scanner 160 is another one that deflects in the vertical direction as will be described later. It also has a pair of electrodes.

The collimator 170 uses the property that ions B, which are charged particles, are deflected in a magnetic field, and suppresses the spread of the beam by the difference in the path of each ion that constitutes the ion beam B. 180 is an electromagnet incident in parallel to 180.
Therefore, hereinafter, it may be referred to as “parallelizing electromagnet” as appropriate.

  Although not shown, a chamber maintained at a high vacuum is disposed from the ion source 110 to the substrate 180, and the ion beam B travels from the ion source 110 to the substrate 180 in the chamber.

Next, the basic operation of the conventional ion implantation apparatus 100 will be described with reference to FIG.
In the conventional ion implantation apparatus 100, in order to perform ion implantation of a predetermined ion species with a predetermined energy at a uniform density over the entire surface of the ion implantation of the substrate 180, for example, about 30 keV from the ion source 110. The ion beam B extracted with this energy is deflected by the mass separator 120, and only predetermined ion species are selected by the mass separation slit 130.

The selected ion beam B is accelerated or decelerated to an energy of about 10 to 500 keV by the acceleration tube 140, and the electrostatic type scanner 160 having two pairs of electrodes that scan the ion beam B in the horizontal and vertical directions described above. For example, an external electric field having a period of about 1 kHz is applied to scan the scanning surface of the substrate 180.
Here, for the sake of explanation, the ion beam B is assumed to be scanned in a horizontal plane.
Further, the electrostatic type scanner 160 that scans the ion beam B with an external electric field has been taken up. However, the scanner 160 may be a magnetic type instead of the electrostatic type.

  In addition, as shown in FIG. 8, in order to adjust the beam shape of the ion beam B on the substrate 180, an adjustment device such as a quadrupole lens 150 is installed between the acceleration tube 140 and the scanner 160. Is common.

As shown in FIG. 8, a collimator 170 for collimating the beam B is installed on the downstream side of the scanner 160.
The substrate 180 is mechanically scanned at a speed of about 1 Hz in a plane orthogonal to the optical axis of the ion beam B and the scanning plane.

JP-A-4-253149 Japanese Patent Laid-Open No. 3-71545 JP-A-11-7915 JP-A-7-105901

  By the way, as the miniaturization of the semiconductor device progresses, the height ratio to the width of the structure wall due to the three-dimensional structure on the semiconductor device also increases, and the two-dimensional parallelism of the incident ion beam in the same semiconductor substrate surface is improved. Is required.

In the conventional ion implantation apparatus, as described above, the semiconductor substrate is mechanically scanned in parallel to the ion beam, but the angle of the ion beam in the mechanical scanning direction is not questioned.
In a collimator lens using an electromagnet, the vertical lens action is different from the ion beam scan trajectory in the horizontal direction in the lens. Have the problem of being.

  In order to inject an ion beam whose angle is controlled with high accuracy into a semiconductor substrate, if the hybrid scan method is taken as an example, the ion beam scanning direction and the semiconductor substrate scanning direction are Although it is necessary to manage the ion beam angle (parallelism) in both directions and minimize the deviation from the parallelism, it is not controlled and managed by the conventional apparatus.

Also, the problems of Patent Documents 1 to 3 of the prior art will be described.
First, in the invention of Patent Document 1, a deviation in parallelism with respect to the scan axis of the ion beam occurs with respect to the scan width of the ion beam in accordance with the uniform region of the magnetic field in the deflection lens for scanning the ion beam in parallel. ing.
In order to reduce the deviation in parallelism, a large deflection lens in which the magnetic field of the deflection lens is uniform over a wide area may be used. However, the ion implantation apparatus becomes enormous.

Next, the invention of Patent Document 2 aims to obtain a parallel scan beam by providing a limiting mask and setting the ion beam scan to a minute angle.
In order to uniformly implant the wafer surface, a considerable number of beams must be superimposed (coated) in the mask opening area, and mechanical injection alone requires a lot of time for the implantation process, resulting in poor productivity. It will be.

  Next, in the invention of Patent Document 3, the ion beam is fixed without being scanned, and the substrate is XY mechanically scanned, and in the same manner as in Patent Document 2, in order to maintain the implantation uniformity within the wafer surface. Requires a lot of processing time and lacks productivity.

  An object of the present invention is to solve the above-described conventional problems and to provide an ion implantation apparatus capable of collimating an ion beam in two directions.

In the ion implantation apparatus according to the present invention, a desired ion species is extracted from an ion source for generating ions, accelerated or decelerated to a desired energy, and an ion beam is applied to an implantation surface of a substrate by a scanner. In an ion implantation apparatus that scans at least in a one-dimensional plane and collimates and implants by a collimator, and has an end face inclined at a predetermined angle with respect to the traveling direction of the ion beam, and the traveling direction of the ion beam a pair of electromagnets polarity of the magnetic pole changes along the opposed to a magnetic field type lens formed by such that different magnetic poles polarities facing across the trajectory of the ion beam, and located downstream of the collimating device The configuration.

The ion implantation apparatus according to claim 2, wherein a desired ion species is extracted from an ion source for generating ions, accelerated or decelerated to a desired energy, and an ion beam is applied to an implantation surface of a substrate by a scanner at least one-dimensional surface. by scanning an inner, in an ion implantation apparatus for injecting in parallel by collimating device, a pair of electrodes disposed referred pairs across the ion beam, and arranged in order relative to the traveling direction of the ion beam has first to third three pairs of electrodes consisting Te, wherein the first and third two pairs of electrodes to a ground potential, said second pair of electrodes an electrostatic lens with a controllable potential Is arranged on the downstream side of the parallelizing device.

  The ion implantation apparatus according to claim 3, wherein the ion implantation apparatus has a focal point on a plane perpendicular to a scanning plane of the ion beam synthesized by the collimation apparatus and the magnetic field type lens or the electrostatic lens. The second scanner is arranged so that the deflection centers coincide with each other.

Since the ion implantation apparatus of the present invention is configured as described above, it has the following excellent effects.
(1) When configured as described in claims 1 and 2, ion implantation parallel in two directions can be realized regardless of the irradiation position on the semiconductor device substrate.

(2) When configured as described in claim 3, parallel ion implantation with higher accuracy of about ± 0.2 ° or less in two directions can be realized regardless of the irradiation position on the semiconductor device substrate.
(3) Further, even if the ratio of the height to the width of the structure wall due to the three-dimensional structure on the semiconductor device is increased, the ion beam is applied to the inner wall of the semiconductor device over the entire region of the same semiconductor device substrate. Necessary ion implantation can be performed without unnecessary irradiation.

  Since the feature of the ion implantation apparatus of the present invention is the realization of parallelization of the ion beam in two directions, before the explanation of the ion implantation apparatus of each embodiment, a general ion beam for collimation is used. The principle will be described with reference to FIG. 7, and then the first and second embodiments of the ion implantation apparatus of the present invention will be described with reference to FIGS.

First, a general principle for making the ion beam parallel will be described with reference to FIG.
FIG. 7 is a side view showing a partial configuration of an ion implantation apparatus in order to explain the principle for making the ion beams parallel.

In order to irradiate the substrate 180 with the ion beam B in parallel over a wide range, in addition to the configuration of the conventional ion implantation apparatus 100, in principle, the configuration is as shown in FIG.
In FIG. 7, 20 is a scanner, F1 is a deflection center of the scanner 20, 30 is an optical element having a convex lens action with respect to an ion beam, and 180 is a semiconductor device substrate.
Here, the optical element 30 having the convex lens action corresponds to a collimating electromagnet or an electrostatic lens.

  As shown in FIG. 7, the incident side focal point of the optical element 30 having a convex lens action is made coincident with the deflection center F1 of the scanner 20, and the ion beam B that is focused on the deflection center F1 is incident to scan. The ion beam B is irradiated on the substrate 180 in parallel without depending on the deflection angle in the vessel 20.

First Embodiment Next, a first embodiment of an ion implantation apparatus according to the present invention will be described with reference to FIGS.
FIG. 1 is a side view showing the structure of a magnetic field type lens 40 used in the first embodiment of the ion implantation apparatus of the present invention.
FIG. 2 is a plan view showing the structure of the magnetic field type lens 40 used in the first embodiment of the ion implantation apparatus of the present invention.

The configuration of the ion implantation apparatus according to the present embodiment is characterized in that, in the conventional ion implantation apparatus 100 (see FIG. 8), the magnetic field type lens (hereinafter referred to as “lens”) shown in FIG. 1 and FIG. , Referred to as a “variable edge magnetic field type lens”) 40.
Therefore, the variable edge magnetic field type lens 40 will be mainly described below, and other configurations will be omitted because the same configuration as that of the conventional ion implantation apparatus 100 is used.

First, the basic configuration of the variable edge magnetic field type lens 40 will be described with reference to FIGS. 1 and 2.
1 and 2, a coordinate system is used in which the traveling direction of the ion beam is the Z axis, the horizontal direction is the X axis, and the vertical direction is the Y axis.

The basic configuration of the variable edge magnetic field type lens 40 is that electromagnets 43 and 47 in which the polarities of the magnetic poles 41, 42, 45, and 46 change along the traveling direction (Z axis) of the ion beam B with the orbit of the ion beam B interposed therebetween. The magnetic poles 41 and 45 and the magnetic poles 42 and 46 having different polarities are arranged so as to face each other.
As shown in FIG. 2, the end faces (edges) 40 a and 40 b of the variable edge magnetic field type lens 40 have a shape inclined at a predetermined angle with respect to the traveling direction of the ion beam B.
In FIG. 1, 44 and 48 are coils for exciting the set of electromagnets 43 and 47, respectively, and P is a reference plane including the trajectory of the ion beam B.

That is, as shown in FIG. 1, when the electromagnet 43 is excited by the exciting coil 44 and the upstream magnetic pole 41 of the ion beam B is an N pole, the downstream magnetic pole 42 is an S pole.
In addition, the upstream magnetic pole 45 of the electromagnet 47 disposed to face the electromagnet 43 has an S pole, and the downstream magnetic pole 46 has an N pole.

Next, the lens action of the variable edge magnetic field type lens 40 with the above configuration will be described.
The magnetic field generated by exciting the variable edge magnetic field type lens 40 has components such as A, B, C, and D as indicated by arrows in FIG.
Here, since the components A and B are equal in intensity and opposite in direction, the ion beam B passing there is slightly deviated in its trajectory but the angle is not changed.
Therefore, the lens action on the XZ plane is small.

On the other hand, the components C and D are zero on the reference plane P due to their symmetry, and become stronger as the distance from the reference plane P increases.
The first approximation is proportional to the distance from the reference plane P.
Further, when the angle between the component C or D and the ion beam B passing through is Φ, the generated Lorentz force is proportional to cos Φ.
Therefore, the end face (edge) 40a, 40b of the variable edge magnetic field type lens 40 is inclined by a predetermined angle with respect to the traveling direction of the ion beam B as shown in FIG. be able to.

Second Embodiment Next, a second embodiment of the ion implantation apparatus of the present invention will be described with reference to FIGS.
FIG. 3 is a side view showing the structure of the electrostatic lens 50 used in the second embodiment of the ion implantation apparatus of the present invention.
FIG. 4 is a plan view showing the structure of the electrostatic lens 50 used in the second embodiment of the ion implantation apparatus of the present invention.

The structural features of the ion implantation apparatus of the present embodiment are similar to those of the first embodiment described above, in the conventional ion implantation apparatus 100 (see FIG. 8), on the downstream side of the parallelization apparatus 170. The electrostatic lens (hereinafter referred to as “two-dimensional Einzel lens”) 50 shown in FIGS.
Accordingly, the description of the two-dimensional Einzel lens 50 will be mainly described below, and the description of other configurations will be omitted because the same configuration as that of the conventional ion implantation apparatus is used.

First, the basic configuration of the two-dimensional Einzel lens 50 will be described with reference to FIGS.
3 and 4, as in FIGS. 1 and 2, a coordinate system is used in which the traveling direction of the ion beam B is the Z axis, the horizontal X axis, and the vertical direction is the Y axis.

  The basic configuration of the two-dimensional Einzel lens 50 is that the first to third three pairs of electrodes 52, 54, and 56 are arranged in order symmetrically with respect to the trajectory of the ion beam B, and the first and third two pairs are arranged. The electrodes 52 and 56 are set to the ground potential, and the second pair of electrodes 54 between them are configured so that the potential can be controlled.

The ion implanter according to claim 3, said collimating device, the incident-side focal point of a plane perpendicular to the scanning plane of the ion beam synthesized from the magnetic lens, so as to match the deflection center The second scanner is arranged in the configuration.
5. The ion implantation apparatus according to claim 4, wherein the deflection center is made to coincide with the incident side focal point in a plane perpendicular to the scanning surface of the ion beam synthesized by the collimating device and the electrostatic lens. The second scanner is arranged.

Next, the principle of realizing the parallelization of the ion beam B in two directions by adding the variable edge magnetic field type lens 40 or the two-dimensional Einzel lens 50 will be described with reference to FIGS.
5 and 6 are views for explaining the principle of parallelization of the ion beam B in two directions, FIG. 5 is a side view, and FIG. 6 is a plan view.
In FIG. 5, the correction lens 40 (50) is formed by the variable edge magnetic field type lens 40 or the two-dimensional Einzel lens 50 according to the present invention provided between the parallelizing device 170 and the substrate 180.

(2) When configured as described in claim 3 or 4 , parallel ion implantation with higher accuracy of about ± 0.2 ° or less in two directions can be realized regardless of the irradiation position on the semiconductor device substrate. .
(3) Further, even if the ratio of the height to the width of the structure wall due to the three-dimensional structure on the semiconductor device is increased, the ion beam is applied to the inner wall of the semiconductor device over the entire region of the same semiconductor device substrate. Necessary ion implantation can be performed without unnecessary irradiation.

However, along with this, the collimating electromagnet 170 has a lens action also on the YZ plane.
In the conventional ion implantation apparatus 100, this lens action is not taken into consideration.
As shown in FIG. 5, the deflection center F2 of the second scanner 22 is made to coincide with the incident side focal point of the convex lens in the YZ plane synthesized by the correction lens 40 (50) according to the present invention and the collimating electromagnet 170. By making the ion beam B focused on the YZ plane incident, the ion beam B on the YZ plane can be made parallel.
Accordingly, with such a configuration, an ion beam B parallel in two directions on the XZ plane and the YZ plane can be obtained.

In the conventional ion implantation apparatus 100, as described above, the parallelism of the ion beam B has been considered only in one direction.
However, according to the present invention, parallel ion implantation of about ± 0.2 ° or less in two directions can be realized regardless of the irradiation position on the substrate 180.
Thereby, even if the ratio of the height to the width of the structure wall due to the three-dimensional structure on the semiconductor device is increased, unnecessary irradiation of the ion beam B on the inner wall of the semiconductor device is performed over the entire region of the same semiconductor substrate 180. Necessary ion implantation can be performed without performing the above steps.

It is a side view which shows the structure of the magnetic field type lens used for 1st Embodiment of the ion implantation apparatus of this invention. It is a top view which shows the structure of the magnetic field type lens used for 1st Embodiment of the ion implantation apparatus of this invention. It is a side view which shows the structure of the electrostatic lens used for 2nd Embodiment of the ion implantation apparatus of this invention. It is a top view which shows the structure of the electrostatic lens used for 2nd Embodiment of the ion implantation apparatus of this invention. It is a side view for demonstrating the principle by which the collimation of the ion beam in two directions is implement | achieved. It is a top view for demonstrating the principle by which the collimation of the ion beam in two directions is implement | achieved. It is a side view which shows the partial structure of an ion implantation apparatus, in order to demonstrate the principle for making an ion beam parallel. It is a top view which shows schematic structure of the conventional ion implantation apparatus.

Explanation of symbols

20: Scanner
22: Second scanner
40: Magnetic lens 40a, 40b: Electromagnet end faces 41, 42, 45, 46: Magnetic poles
43, 47: Electromagnet
44, 48: Coil
50: Electrostatic lens 52, 54, 56: First to third electrodes
100: Ion implanter
110: Ion source
170: Parallelizing device (parallelizing electromagnet)
180: Substrate
B: Ion beam

Claims (4)

A desired ion species is extracted from an ion source that generates ions, accelerated or decelerated to a desired energy, and an ion beam is scanned in an at least one-dimensional plane on a substrate implantation surface by a scanner, and is collimated by a collimator. In an ion implantation apparatus
A pair of electromagnets having end faces inclined at a predetermined angle with respect to the traveling direction of the ion beam and changing the polarity of the magnetic pole along the traveling direction of the ion beam have different polarities across the trajectory of the ion beam. An ion implantation apparatus characterized in that a magnetic field type lens formed so as to face each other so that magnetic poles face each other is arranged on the downstream side of the parallelizing device. A desired ion species is extracted from an ion source that generates ions, accelerated or decelerated to a desired energy, and an ion beam is scanned in an at least one-dimensional plane on a substrate implantation surface by a scanner, and parallelized by a collimator. turned into an ion implantation apparatus for implanting, a pair of electrodes disposed referred pairs across the ion beam, the first to third three pairs formed by arranging in sequence with respect to the traveling direction of the ion beam An electrostatic lens having electrodes, the first and third pairs of electrodes having a ground potential, and the second pair of electrodes having a controllable potential is disposed downstream of the collimating device. An ion implantation apparatus characterized by that. A second scanner is arranged so that the center of deflection coincides with the incident side focal point in a plane perpendicular to the scanning surface of the ion beam synthesized by the collimating device and the magnetic field type lens. The ion implantation apparatus according to claim 1. A second scanner is arranged so that the center of deflection coincides with the incident side focal point in a plane perpendicular to the scanning surface of the ion beam synthesized by the collimator and the electrostatic lens. The ion implantation apparatus according to claim 2.

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