JPH05166483A - Ion implantation device - Google Patents

Abstract

PURPOSE:To effect uniform ion implantation through scan made by beams from a compact-sized ion source and after selection of a desired ion kind. CONSTITUTION:Substantially parallel beams each having a slit configuration in section are drawn out from an ion source 1 by use of a draw-out voltage and an acceleration voltage. The beams are caused to pass through a fixed magnetic field of a sector magnet 3 for conducting mass analysis. A difference is exhibited in movement quantity according to the ion kind, and, as a result, different locuses of movement are described. By this, a desired kind of ion is selected and in subsequence unnecessary ion kinds are eliminated by an analyzing slit 4. The desired kinds of ions pass through the slit 4 and are incident upon a sextet pole magnetic lens 5 for re-shaping. Subsequently, the desired kinds of ions transit through a drift space to reach the surface of a substrate 9, and are irradiated thereupon in the form of a horizontally elongate slit. At this time, the beams are each corrected to become parallel by an electric field lens 6 located before the substrate 9. On the other hand, the ion source 1 has its ion draw-out port swung by a drive means 2 in the vertical direction, so that the substrate 9 surface is uniformly scanned by the ion beams. This enables uniform ion implantation.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an ion implanter.

[0002]

2. Description of the Related Art Ion implanters are used for manufacturing various semiconductor devices, modifying the surface of materials for wear resistance, corrosion resistance, etc.
It is widely used for forming a thin film such as a superconducting film on the surface of an object. This ion implantation apparatus usually turns a source gas into plasma, emits an ion beam through an ion passage hole of an ion source electrode in front of the plasma source, irradiates the surface of an object, and implants ions.

Therefore, the area range in which ions can be implanted depends on the diameter of the ion source. In order to perform ion implantation over a wide area, a large-diameter ion source that requires a special processing technique is used, and the ion beam from the ion source is accelerated to implant ions into a target such as a substrate.

[0004]

However, in such a conventional device, all the ion species extracted from the ion source are injected into the substrate or the like. Therefore, for example, when P is injected into the semiconductor substrate using PH ₃ gas, H is also injected at the same time, which serves as an energy source to heat the substrate,
There are problems such as deterioration of semiconductor quality.

The beam intensity distribution at each part of the ion implantation position depends only on the distribution of the ion passage holes of the ion source electrode. Therefore, the degree of freedom for adjusting the beam intensity distribution is limited. Further, as the implantation area increases, the diameter of the ion source must be increased, which makes manufacturing more difficult.

Therefore, the present invention does not require the use of a large-diameter ion source, uses a compact ion source, and can reliably and uniformly implant a large area by scanning with an ion beam from the ion source. It is an object of the present invention to provide an ion implanter capable of selecting a desired ion species from the ions extracted from a source and performing ion implantation with the ion species.

[0007]

According to the above object, the present invention provides an ion source having a slit-shaped ion extraction port elongated in a certain direction, and scanning the ion extraction port with an ion beam at an ion implantation position to an object. for,
Ion source driving means for oscillating in a direction transverse to the longitudinal direction of the ion extraction port, ion analysis means for selecting and passing a desired ion species from the ion beam emitted by the ion source, beam at a position of ion implantation to an object Beam shaping means for shaping the distribution shape into a slender shape corresponding to the longitudinal direction of the ion extraction port, and making the ion beam emitted from the beam shaping means perpendicular or nearly perpendicular to the surface of the object. The present invention provides an ion implantation apparatus characterized in that it is provided with beam collimating means for collimating the beam.

The ion analyzing means may include, for example, a mass analyzing electromagnet for selecting a desired ion species from the ion beam emitted by the ion source. Such a mass analysis electromagnet allows an ion beam to pass through a magnetic field, and has different momentums depending on the ion species, thereby causing different ion motion trajectory curvatures. Further, it is conceivable to include an analysis slit which removes unnecessary ions from the ions emitted from the mass analysis electromagnet and allows desired ions to pass therethrough. When a mass analysis electromagnet is adopted, as the ion source driving means,
Typically, an ion extraction port of the ion source may be swung in the magnetic flux direction of the mass analysis electromagnet.

Further, the ion source driving means may be configured to swing the ion extraction port by changing the angle of attack around the ion beam entrance of the mass analysis electromagnet. Further, the mass analysis electromagnet corrects the ion beam entrance / exit end of the pole piece for beam shift in a direction perpendicular to the scanning direction by the beam at the ion implantation position due to the swing of the ion extraction port. It can be considered that the film is formed with a finite radius of curvature.

Further, in order to avoid the problem that a large amount of beam is irradiated to a component supporting an ion implantation target and particles sputtered from this component enter the ion implantation target and lead to contamination of impurities. The mass analysis electromagnet can change the beam width (beam width corresponding to the longitudinal direction of the ion extraction port of the ion source) at the ion implantation position to the target so that the ion beam incident angle to the magnet and the ions from the magnet are changed. A means for changing at least one of the beam emission angles may be provided.

The means for changing the incident angle and / or the outgoing angle is based on the following theoretical concept and experiment. That is, in principle, if the beam is weakly focused when entering the analyzing electromagnet and strongly focused when it is emitted, the divergence angle of the beam is increased, and the beam width at the ion implantation position can be increased. If the beam is focused and the beam focusing is suppressed at the time of emission, the divergence angle of the beam becomes small and the beam width at the ion implantation position becomes small. According to the experiment, the beam incident angle to the mass analysis electromagnet (the sector magnet in the experiment) is increased in the positive direction (that is, the beam focusing is weakened), and the beam emission angle from the magnet is increased in the negative direction. As the focus of the beam is increased (ie, the beam focus is increased), the beam width increases.

The beam shaping means may be configured to include, for example, an electromagnet lens for beam shaping. In this case, the electromagnet lens may be, for example, a hexapole electromagnet lens. As the beam collimating means, typically, a means including an electric field lens for collimating the ion beam can be considered.

[0013]

According to the ion implantation apparatus of the present invention, the slit-shaped ion beam emitted from the ion source and having a long slit in a certain direction passes through the ion analysis means, so that only the desired ion species necessary for the ion implantation or the ion species are obtained. The main component is the ion beam, which is then shaped by the ion beam shaping means, which is then collimated by the beam collimating means to move through the drift space and form an elongated beam distribution corresponding to the ion extraction port on the target surface. While being irradiated, the ion source is driven by the ion source driving means to swing the ion extraction port, whereby the surface of the target object to be ion-implanted is scanned by the ion beam, and desired ions are spread over a desired range of the target surface. The seed ensures reliable and uniform ion implantation.

When the ion analysis means includes the mass analysis electromagnet and the analysis slit, the ion beam emitted from the ion source passes through the mass analysis electromagnet to select a desired ion species from the ion beam. Then, unnecessary ions are removed by the analysis slit, and desired ion species pass through. In this case, the ion source driving means swings the ion extraction port of the ion source in the magnetic flux direction of the mass analysis electromagnet. This swinging is performed, for example, by changing the angle of attack around the ion beam entrance of the mass analysis electromagnet.

In the mass analyzing electromagnet, the ion beam entrance / exit end of the pole piece is perpendicular to the beam scanning direction at the ion implantation position due to the swinging of the ion extraction port (longitudinal length of elongated beam distribution). Direction), the aberration generated by the ion beam passing through the mass analysis electromagnet is corrected by the finite radius of curvature to correct the ion implantation position. The beam shift in the direction orthogonal to the beam scanning direction at is corrected.

The ion beam incident angle on the magnet and the ion beam incident angle on the magnet so that the mass analysis electromagnet can change the beam width at the ion implantation position to the target object (the beam width corresponding to the longitudinal direction of the ion extraction port of the ion source). When a means for changing at least one of the ion beam exit angles from the magnet is provided, the beam entrance and / or exit angles can be changed by the means depending on the size of the ion implantation target, whereby the Ions can be irradiated as much as possible within the range according to the size of the target object, a large amount of beam is irradiated to the part supporting the ion implantation target, and the particles sputtered from this part enter the target object to be ion-implanted. The problem of being mixed is avoided.

The beam shaping means is 6 for beam shaping.
When including an electromagnet lens, such as a dipole electromagnet lens, the lens provides an elongated beam distribution at the ion implantation location, corresponding to the shape of the ion extraction aperture. When the beam collimating means includes an ion beam collimating electric field lens, the beam is collimated by the action of the electric field lens.

The mass analysis electromagnet, the beam shaping electromagnet lens, and the beam collimating electric field lens can control mass analysis, beam shaping, and beam collimating by controlling their power sources. For example, the electric field lens includes a beam scanning area at an ion implantation position based on a swinging motion of an ion source by an ion source driving device, an ion species selected by a mass analysis electromagnet, a beam shaping state by a beam shaping electromagnet lens, and the like. It may be controlled according to the conditions.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing a part of one embodiment in a partial horizontal section, and FIG. 2 is a side view showing a part of the apparatus in FIG. This ion implanter has a vertical 1
ion source 1 having an extraction shape of 20 cm and a width of 20 cm, an ion source driving device 2, a mass analysis sector magnet 3,
The analysis slit 4, the hexapole magnet lens 5 and the electric field lens 6 are provided.

An ion beam close to parallel is extracted from the ion source 1 by applying an extraction voltage and an acceleration voltage. The cross-sectional shape of the entire extracted beam is a slit shape that is long in the horizontal direction. As shown in FIG. 3, the sector magnet 3 includes a pair of upper and lower pole pieces 33 (curvature radius R = 5) on a yoke 32 around which a current-carrying coil 31 is wound.
(0 cm) is provided at intervals of 10 cm, and the ion beam passes between the pole pieces. In order to enable horizontal and vertical focusing and divergence of the ion beam, this magnet is provided with a function of obliquely entering and exiting the pole piece, as shown in FIG. That is, this magnet pole piece 3
The end of the beam 3 on the beam incident side is formed in a half moon shape in a plan view, and as shown in FIG.
The beam incident angle α can be changed by rotating around 31. The rotation of the half-moon portion 330 can be performed by driving the shaft 331 by the motor 333 via the transmission device 332. On the other hand, the exit side end of the pole piece 33 is also formed so as to obtain the beam exit angle β. Then, by controlling the attitude of the meniscus 330, the incident angle α can be selected and the beam width or size in the horizontal direction X at the ion implantation position B can be controlled. Here, the incident angle α is 38 degrees and the outgoing angle β is -40 degrees. The choice of this angle is necessary for the beam to be focused at the analysis slit 4.

Further, the aberration generated by the beam passing through the magnet 3 is corrected, and the beam is moved in the horizontal direction X even if the ion implantation position is scanned in the vertical direction Y.
In order to prevent the deviation, the cross section of the pole piece at the entrance and exit ends has a finite radius of curvature. In this example, the entrance side radius of curvature r1 = 1 m, the exit side radius of curvature r2 = −0.33
It is set to 3 m.

In this example, the distance L1 between the ion source 1 and the sector magnet 3 is 50 cm, and the distance L2 between the sector magnet 3 and the analysis slit 4 is 22.5 cm.
Distance L3 = 6 between the dipole magnet lens 5 and the electric field lens 6
The distance L4 from the electric field lens 6 to the ion implantation position B is set to 0 cm and L4 = 10 cm. The incident angle changing means of the sector magnet 3 is not limited to the above. Further, when such an incident angle changing means is not provided, a sector magnet having a predetermined entrance / exit angle may be exchanged and used so that a desired horizontal beam width or size at the ion implantation position B can be obtained.

The ion source driving device 2 meshes a worm gear 22 with a fan-shaped (sector) gear 21 connected to the ion source 1, and the worm 22 can be rotated by a motor 23 in forward and reverse directions. When the gear 21 is driven by the motor, the ion extraction port of the ion source 1 is
By changing the angle of attack γ (see FIG. 2) about the beam incident end central position A of the sector magnet 3, the sector magnet 3 can be swung in the vertical (up and down) direction that is the magnetic flux direction. The ion source driving device is not limited to that of this embodiment.

As shown in the schematic cross section of FIG. 4, the hexapole magnet 5 has six cores each having a coil wound around it at equal angular intervals, and a current is passed through each coil. N poles and S poles are alternately formed. The magnetic field strength is controlled by controlling the magnitude of the current flowing through the coil, and the beam distribution shape at the ion implantation position B is determined by the ion extraction port of the ion source. Can be shaped into an elongated slit shape in the horizontal direction corresponding to. In this example, the magnet 5 is set to have a magnetic field effective length of 20 cm, an inner diameter r5 of 40 cm, and a magnetic force of 1 KG.

The electric field lens 6 is formed by arranging three ring-shaped electrodes, both ends of which are fixed to the ground potential, and the voltage applied to the intermediate electrode is controlled to collimate the ion beam toward the ion implantation position B. Thus, the ion implantation can be performed in a state of being vertical or nearly vertical to the surface of the ion implantation target placed at the position B. Here, the ring-shaped electrode interval is set to 10 cm and the inner diameter is set to 60 cm, and a voltage of 30 KV is set for an ion beam of 100 KeV.

With the apparatus of the embodiment described above, for example, on the surface of the semiconductor substrate 9 arranged at the ion implantation position B,
The case of implanting P ions with PH ₃ as the source gas in the ion source will be described. The substrate 9 is 40c in this example
The square was m × 40 cm, and the edges were aligned in the horizontal direction X and the vertical direction Y. First, an ion beam having a slit-shaped cross section, which is nearly parallel, is extracted from the ion source 1. This ion beam passes through a constant magnetic field in the sector magnet 3 for mass analysis, and thus a difference in momentum is generated depending on the ion species, and different loci of movement are drawn, whereby the desired ion species required for ion implantation ( P) is selected, then unwanted ionic species are removed in the analysis slit 4 and the desired ionic species pass through.

The ion beam that has passed through the analysis slit 4 enters the hexapole magnet lens 5. Beam shaping is performed by this lens system, and the beam collimating electric field lens 6 is further provided.
The laser beam is collimated and moves in the drift space, and the beam is distributed in an elongated shape corresponding to the ion extraction port, and is surely and uniformly irradiated in a state of being perpendicular or nearly perpendicular to the surface of the substrate 9.

On the other hand, when the ion source 1 is driven by the ion source driving device 2, the ion extraction port is vertically swung, so that the surface of the substrate 9 is uniformly scanned by the ion beam, and thus the desired surface of the substrate is obtained. Using the above ion species, it is possible to uniformly and satisfactorily ion-implant each part. In the above-mentioned embodiment, when it was examined in advance how the beam shape at the ion implantation position B changed according to the swing angle (angle of attack γ) of the ion source 1 by the ion source driving device 2, the beam was found to be Moved only in the vertical direction Y. It was also found that the beam position at the ion implantation position B into the substrate moves in a first-order relationship depending on the swing angle of the ion source 1. This means that if the beam amount is constant, uniform scanning can be performed while keeping the scanning speed of the ion source 1 constant.

The beam uniformity in the horizontal direction (X) was 10% or less at each position on the substrate 9. 5 and 6 show the beam distribution on the substrate 9 when a uniform beam distribution is given in the ion source 1. In FIG. 5, the horizontal axis Yi is the distance (cm) in the Y direction from the center at position B.
, IY0, IY2, ... are swing angles (angle of attack γ) every 20 mrad starting from 0 mrad of the ion extraction port of the ion source 1, that is, 0 mrad, 20 mrad, 40
mrad ... In FIG. 6, the horizontal axis X
i represents the distance (cm) in the X direction from the center at the position B, and IY0, IY2, ... Are the same as in FIG. 5 and 6, the vertical axis represents the number of beams (beam intensity). When this distribution is statistically processed, 10
% Homogeneity was obtained. Here, the definition of uniformity is as follows.

Uniformity = standard deviation of beam distribution / average value of beam distribution However, this is for the distribution in a region of 40 cm in the horizontal direction. Further, since there is almost no change in the beam size, the beam current value is constant for a beam having a uniform beam current density, so that the uniformity of implantation can be obtained without changing the scanning speed of the ion source 1. You can

For comparison, when the electric field lens 6 was omitted, the divergence angle of the beam emitted from the hexapole magnet lens 5 became 200 mrad. In particular, although the divergence in the horizontal direction X is large and the divergence in the vertical direction Y is smaller than that in the horizontal direction X, the inclination of the beam (beam incident angle) at the ion implantation position was large. As described above, if the implantation is performed while the divergence angle and the incident angle of the beam are large, a shadow is formed due to the structure of the device and an unimplanted region occurs. This causes deterioration of injection uniformity.

However, when the electric field lens 6 is arranged and a high voltage is applied as in the embodiment, the divergence of the beam in the horizontal direction X is suppressed by the lens effect and the vertical direction Y is applied.
In, the tilt of the beam was suppressed, and the beam was collimated as a whole and was incident on the substrate 9 in a state of being vertical or nearly vertical. This is important for achieving high quality ion implantation.

In FIG. 7A, how the beam divergence angle in the horizontal direction X and the beam tilt in the vertical direction Y on the substrate 9 change according to the change in the voltage V applied to the electric field lens 6. Indicates whether to do. In the vertical direction Y, the beam divergence angle does not change significantly even with the lens voltage, but the angle of incidence on the substrate 9 changes, so only the tilt of the beam is noted. The divergence angle (DX) shown in FIG. 7A is the horizontal direction X.
Is the maximum value of the divergence angle of. Actually, it has an angle from + DX to -DX. Positive values cause the beam to diverge at the substrate,
Negative values mean focus. The beam tilt (DY) is the tilt in the vertical direction Y. A positive value means that the beam is tilted in the positive direction of the Y (vertical) axis on the substrate and a negative value is tilted in the negative direction.

According to FIG. 7 (A), in order to keep the divergence angle in the horizontal direction near 0 degrees and the beam tilt in the vertical direction near 0 degrees, a voltage of about 30 KV is applied to the electric field lens 6. I understand that it is good. Further, the inclination of the beam in the vertical direction Y changes depending on the swing angle γ of the ion source 1, but how much is affected by the lens voltage is shown in FIG. 7B.
Shown in the figure. In this figure (B), DYo is the case where no voltage is applied to the electric field lens 6, and DY6 is 3
The case where 0 KV is applied is shown. From this figure, 30
It can be seen that the slope is suppressed to half by applying the voltage of KV.

From the calculation based on these, the beam can be corrected to be parallel by the electric field lens 6 installed in front of the substrate 9 and can be made incident on the substrate vertically or substantially vertically.

[0036]

According to the ion implantation apparatus of the present invention, it is not necessary to use a large-diameter ion source, a compact ion source is used, and the ions are scanned by the ion beam from the ion source. Ion implantation can be performed reliably and uniformly by beam injection, and a desired ion species can be selected from the ions extracted from the ion source and ion implantation can be performed with the ion species, which enables the production of high quality devices. Becomes

When a mass analysis electromagnet is adopted as the ion analysis means, the incident angle and / or the exit angle of the ion beam with respect to the magnet are changed so that the beam width at the position of ion implantation into the target object (of the ion source). The beam width (corresponding to the longitudinal direction of the ion extraction port) is changed, and the scanning area by the ion beam is changed so that the beam is irradiated to an extra area outside the range according to the size of the ion implantation target. Can be suppressed to a minimum, which can suppress contamination of the ion implantation target with contaminants.

[Brief description of drawings]

FIG. 1 is a plan view showing a part of one embodiment in a horizontal cross section.

FIG. 2 is a side view showing a part of the apparatus of FIG. 1 in a developed state and partly in a vertical cross section.

FIG. 3 is a schematic end view of a sector magnet.

FIG. 4 is a diagram showing a schematic example of a cross section of a hexapole magnet lens.

FIG. 5 is a graph showing a vertical beam distribution on a substrate.

FIG. 6 is a graph showing a horizontal beam distribution on a substrate.

FIG. 7A is a graph showing the relationship between the voltage applied to the electric field lens, the beam divergence angle in the horizontal direction at the ion implantation position, and the beam tilt in the vertical direction, and FIG. It is a graph which shows the relationship between a beam inclination and an electric field lens voltage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ion source 2 ion source drive device 3 sector magnet 33 pole piece 330 half moon part 331 axis 332 transmission device 333 motor 4 analysis slit 5 6 quadrupole magnet lens 6 electric field lens 9 substrate

Claims (8)

[Claims] 1. An ion source having a slit-shaped ion extraction port that is long in a certain direction, and a direction that traverses the ion extraction port in the longitudinal direction of the ion extraction port for scanning with an ion beam at an ion implantation position on an object. Source driving means for oscillating the ion source, ion analysis means for selecting and passing a desired ion species from the ion beam emitted from the ion source, and a beam distribution shape at an ion implantation position to an object of the ion extraction port. Beam shaping means for shaping an elongated shape corresponding to the longitudinal direction, and a beam for collimating the beam so that the ion beam emitted from the beam shaping means is incident on the surface of the object in a state of being perpendicular or nearly perpendicular. An ion implantation apparatus comprising a collimating means. 2. The ion analyzing means removes unnecessary ions from the mass analysis electromagnet for selecting a desired ion species from the ion beam emitted from the ion source and the ions leaving the mass analysis electromagnet to remove the desired ion. 2. The ion implantation apparatus according to claim 1, further comprising an analysis slit that allows the ion source driving means to swing the ion extraction port of the ion source in the magnetic flux direction of the mass analysis electromagnet. 3. The ion implantation apparatus according to claim 2, wherein the ion source driving means swings the ion extraction port by changing an angle of attack around the ion beam entrance of the mass analysis electromagnet. 4. The mass analysis electromagnet corrects a beam shift of an ion beam entrance / exit end of a pole piece thereof in a direction perpendicular to a beam scanning direction at the ion implantation position due to the swing of the ion extraction port. The ion implantation apparatus according to claim 2 or 3, wherein the ion implantation apparatus is formed so as to have a finite radius of curvature. 5. The ion implantation according to claim 2, 3 or 4, wherein the mass analysis electromagnet includes means for changing at least one of an ion beam incident angle to the magnet and an ion beam emitting angle from the magnet. apparatus. 6. The ion implantation apparatus according to claim 1, wherein the beam shaping means includes an electromagnet lens for beam shaping. 7. The ion implanter according to claim 6, wherein the electromagnet lens is a hexapole electromagnet lens. 8. The ion implantation apparatus according to claim 1, wherein the beam collimating means includes an electric field lens for collimating the ion beam.