JP2000285846A - Ion implating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion implating device capable of reducing metal pollution from a protection plate for protecting an inner wall of a beam passage. SOLUTION: A projected wall portion 28 vertically and substantially extending against the surface of a protection plate 27 and having a vertical wall surface 30 to which an unnecessary ion beam 11B is collided is continuously formed on the surface of a protection plate 27 along an extension direction of a beam passage. Thereby, when an unnecessary ion beam 11B is collided to a vertical wall surface 30 of a constitution particle of a wall surface generated accompanying with this is deposited on a surface of the protection plate 27 without flying toward the track of an ion beam 11A selected. Thereby, a metal pollution from the protection plate 27 can be reduced as compared with the conventional case.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implantation apparatus, and more particularly, to an ion implantation apparatus which reduces the amount of impurities mixed from constituent materials of the ion implantation apparatus.

[0002]

2. Description of the Related Art Conventionally, an ion implantation apparatus has been used as an apparatus for controlling physical properties of an object to be implanted such as a semiconductor substrate by irradiating accelerated ions. For example, as shown in FIG. 5, an ion source 1, a mass analyzer 2 for mass-analyzing an ion beam extracted from the ion source 1 into an ion beam composed of only desired ions, and until the ion beam reaches a required energy. An accelerator 3 for accelerating, a deflector 6 including a quadrupole lens 4 for selecting a required ion valence and irradiating an ion beam toward an object to be implanted and a 10 ° magnet unit 5, and an object to be implanted are accommodated. And an injection chamber 7. The ion beam passes through a beam path formed from the ion source 1 to the 10 ° magnet section 5 and passes through the implantation chamber 7.
Is irradiated to the object to be implanted.

An ion beam extracted from the ion source 1 is separated into a necessary ion beam and an unnecessary ion beam by, for example, the mass analyzer 2 and the deflector 6 on the way to the object in the implantation chamber 7. You. In this method, a magnetic field from a mass separation magnet is applied in a direction perpendicular to the traveling direction of an ion beam, and only ions having a required mass are guided in a certain direction along a beam path. At this time, unnecessary ion beams collide with the inner wall surface of the beam path.

Therefore, conventionally, damage to the inner wall surface of the beam passage due to collision with an unnecessary ion beam and metal contamination which is generated by the particle of the inner wall of the beam passage due to the collision with the ion beam and is mixed into the object to be implanted are prevented. For this reason, there is a type in which a protective plate (or liner) made of a high-hardness metal material such as molybdenum is disposed so as to cover the inner wall surface. The protection plate includes a protection plate having a flat surface shape and a protection plate having a projecting wall portion 9 having a mountain-shaped cross section as shown in FIG.

[0005] However, any of the configurations can certainly protect the inner wall surface of the beam path from collision with an unnecessary ion beam, but does not solve the above-mentioned problem of metal contamination. That is, in the protection plate 8 having the protruding wall portion 9 having an isosceles triangular cross section shown in FIG. 6, when the unnecessary ion beam 11B collides with the slope surface 9a of the protruding wall portion 9, the slope 9a is sputtered. The constituent particles fly toward the beam trajectory of the ion beam 11A selected as the impurity (contamination particles) 10, which causes metal contamination to the implanted object. In addition, the protective plate having a flat surface structure has the same problem as described above, and a part of unnecessary ion beams is reflected on the surface of the protective plate and travels toward the object to be implanted. There is also a problem that it is mixed in.

[0006] As described above, metal contamination from the protection plate used for protecting the inner wall of the beam passage and preventing metal contamination has become a serious problem. In particular, a CCD (Charge Coupled Device) has been problematic.
Since the ion implantation step in ice) is very sensitive to metal contamination, it is essential to reduce such metal contamination.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an ion implantation apparatus capable of reducing metal contamination of an object to be implanted from a protection plate for protecting an inner wall of a beam passage. As an issue.

[0008]

In order to solve the above-mentioned problems, the present invention provides a projecting wall portion extending substantially perpendicular to the surface of a protective plate and having a vertical wall surface against which an unnecessary ion beam collides. Are formed continuously on the surface of the protection plate along the extending direction of the beam path.

With this configuration, when an unnecessary ion beam collides with the vertical wall surface of the protruding wall portion, the constituent particles of the wall surface generated along with the collision do not fly toward the selected ion beam trajectory. Deposits on the surface of Thereby, metal contamination from the protection plate can be significantly reduced as compared with the related art.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. The ion implantation apparatus is indicated by 33 as a whole, and includes an ion source 12, an extraction electrode 13, a charge conversion unit 14, a mass analyzer 15, an accelerator tube 18, and a 10 ° magnet unit 19.
Is formed.

The ions generated by the ion source 12 are extracted by an extraction electrode 13, and the positive ions extracted by a charge conversion unit 14 are converted into negative ions, and then selected into an ion beam composed of only desired ions ( It is introduced into an acceleration tube 18 through a mass analyzer 15 for mass analysis. A tube lens 23 is provided at the entrance of the acceleration tube 18.
The beam shape is adjusted before entering the acceleration tube 18. An electron stripper 24 is provided inside the accelerating tube, and the negative ions that reach the electron stripper 24 are converted into positive ions. Of the ions accelerated to the required energy in the accelerating tube 18, the ion value required by the deflector constituted by the quadrupole lens 25 and the 10 ° magnet unit 19 provided at the outlet of the accelerating tube 18. A number of ion beams are selected and irradiated toward a wafer disk 22 holding an object to be implanted such as a semiconductor wafer in an implantation chamber. The wafer disk 22 reciprocates and rotates as indicated by arrows, and is configured to irradiate the ion beam over the entire surface of a plurality of objects to be implanted on the periphery of the wafer disk 22.

The quadrupole lens 25 applies a voltage obtained by superimposing a DC voltage and a high-frequency voltage to four electrodes arranged in parallel with the traveling direction of the ion beam, and passes only ions having a specific mass-to-charge ratio. It is to let. The 10 ° magnet section 19 applies a magnetic field perpendicular to the traveling direction of the ion beam to deflect only the desired ion beam by 10 °.

Between the mass analyzer 15 and the acceleration tube 18 and between the 10 ° magnet unit 19 and the wafer disk 22, the beam analysis apertures 16 and 20 and the Faraday cups 17 and 21 are inserted into the beam paths, respectively. It is possible to detect whether or not a predetermined ion beam has passed.

FIG. 2 shows a state in which the Faraday cup 21 is attached to the exit end of the beam passage 26 corresponding to the 10 ° magnet portion 19. The Faraday cup 21 is composed of two members 21A and 21B. Both members 21A and 21B are provided so that the selected desired ion beam 11A can pass through a beam analysis aperture 20 formed at a position corresponding to the bottom of the cup 21. Is adjusted, and fixed by the fixing member 21C.

Now, as shown by the solid line in FIG.
The ion beam 11A composed of only the desired ions selected by the 0 ° magnet unit 19 passes through the beam passage 26 and passes through the beam analysis aperture 20 formed at the bottom of the Faraday cup 21. On the other hand, the ion beam 11B having an unnecessary ion valence is not deflected and is not deflected.
6 toward the inner wall surface, and unnecessary ion beam 11B
Collides with the surface of a protective plate 27 made of a high-hardness material such as molybdenum, which is disposed so as to cover the inner wall surface of the beam passage 26 colliding.

At this time, as shown in FIG. 3, the unnecessary ion beam 11B is applied to the vertical wall of the projecting wall 28 continuously formed on the surface of the protection plate 27 along the extending direction of the beam path 26. Collision with 30. This vertical wall portion 30 is a protective plate 2
Because it extends substantially perpendicular to the surface of 7,
The constituent particles of the vertical wall portion 30 sputtered by the ion beam irradiating the vertical wall portion 30 from obliquely above and the impurities 32 composed of the colliding ions are scattered toward the surface of the protection plate 27 and then protected. It deposits on the surface of the plate 27.

Therefore, according to the present embodiment, impurities 32 generated by collision with an unnecessary ion beam are
Since the scattering of the selected ion beam 11A toward the trajectory can be suppressed, the movement of the impurity 32 to the implanted object side is suppressed, and the metal contamination of the implanted object can be significantly reduced as compared with the related art. .

In the present embodiment, the surface of the protruding wall portion 28 formed on the surface of the protection plate 27 on the side opposite to the vertical wall surface 30, that is, the surface on which the unnecessary ion beam 11B does not collide,
Unnecessary ions are formed on the top of the protruding wall 28 by forming a curved surface or a linear inclined surface 31 as shown, which is inclined toward the bottom of the vertical wall 30 of the other adjacent protruding wall 28. In addition to preventing a flat surface from which the beam 11B can collide, the projecting wall portion 28
Can be reduced.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited thereto, and various modifications can be made based on the technical concept of the present invention.

For example, in the above embodiment, the protection plate 27
Although the protruding wall portion 28 formed on the surface of FIG. 3 has a cross-sectional shape as shown in FIG. 3, it may have a shape as shown in FIG. That is, a fin-shaped protruding wall portion 29 having a rectangular cross section and extending in a direction substantially perpendicular to the surface of the protection plate 27 'and having a vertical wall surface 30 which collides with an unnecessary ion beam 11B may be used.

In the above embodiment, the protection plate 2 according to the present invention is provided in the 10 ° magnet portion 19 as a deflector.
7 is disposed, but the protective plate 2 is also provided at the position of the quadrupole lens 25.
7 may be provided, and if a similar protective plate 27 is further provided in the mass analyzer 15, the effect of preventing metal contamination can be improved. The mass spectrometer 15
Although a configuration in which the protection plate 27 is disposed only on the target is possible, a configuration in which the protection plate 27 is disposed in the deflector 19 closest to the object to be injected is more preferable.

Further, in the above embodiment, the 10 ° magnet unit 19 for selecting an ion beam having a required ion valence is described as a deflector, but the irradiated ion beam is scanned in the X, Y and Z directions. Of course, the present invention is also applicable to a deflector of the type in which ions are implanted over the entire surface of the object to be implanted.

[0024]

As described above, according to the ion implantation apparatus of the present invention, metal contamination of the object to be implanted from the protection plate for protecting the inner wall of the beam passage can be significantly reduced as compared with the prior art.

Further, according to the structure of the claims, a flat surface on which the unnecessary ion beam can collide with the top of the projecting wall is prevented from being formed, and the interval between the projecting walls is reduced to form the vertical wall. It can be formed with high density.

Furthermore, by arranging the protective plate according to the present invention on the inner wall of the beam path at the portion where the trajectory of the ion beam is deflected, such as a mass analyzer or a deflector, the metal contamination of the implanted object can be further reduced. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an ion implantation apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part in FIG.

FIG. 3 is an enlarged view of a protection plate according to the present invention.

FIG. 4 is a sectional view showing a modification of the configuration of FIG. 3;

FIG. 5 is a schematic configuration diagram of a general ion implantation apparatus.

FIG. 6 is a cross-sectional view illustrating a surface shape of a protection plate in a conventional ion implantation apparatus.

[Explanation of symbols]

11A: Selected ion beam, 11B: Unnecessary ion beam, 12: Ion source, 15: Mass analyzer, 18: Accelerator tube, 19: 10 ° magnet unit, 22: Wafer disk, 26: Beam path, 27: Protection Boards, 28, 29 ...
Projecting wall portion, 30 vertical wall surface, 31 inclined surface, 32 impurity, 33 ion implantation device.

Claims (3)

[Claims] 1. A mass analyzer for mass-analyzing an ion beam consisting of at least desired ions, an accelerator for accelerating the ion beam to a required energy, and a deflector for deflecting the ion beam in the direction of an object to be implanted. An ion implantation apparatus, comprising: a beam path including a beam path, and a protection plate installed to cover an inner wall surface of a predetermined portion of the beam path and protecting the inner wall surface from collision with an unnecessary ion beam. A projecting wall portion having a vertical wall surface extending substantially perpendicular to the surface and having a vertical wall against which the unnecessary ion beam collides is formed continuously on the surface of the protection plate along the extending direction of the beam path. An ion implanter characterized by the following. 2. A surface of the projecting wall portion on which the unnecessary ion beam does not collide is a curved surface inclined from the top of the vertical wall surface to the bottom of the vertical wall surface of another adjacent and adjacent projecting wall portion. The ion implantation apparatus according to claim 1, wherein the ion implantation apparatus has a linear inclined surface. 3. The protection plate is provided inside the mass spectrometer,
The ion implantation apparatus according to claim 1, wherein the ion implantation apparatus is provided inside the deflector.