JPH0746591B2 - Ion implanter - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ion implanter, and more particularly to an ion implanter used in a semiconductor element manufacturing process.

[Conventional technology]

In the ion implantation method used for the impurity diffusion step in the semiconductor manufacturing process, the energy for determining the implantation depth is 10 to 20 as a condition for implanting ions into the wafer.
A high current implanter with a beam current of 1 to 10 mA has been used to increase productivity at 0 kV. That is, it is necessary to traverse a large number of ion beams and wafers in order to implant ions uniformly over the entire surface of the wafer. For example, ion implantation technology can be used for large current machines with large energy power. (ION IMPLANTA
TION TECHNIQUES), SPRINGER SERIES IN ELECTROPHYSICS 10 of electronic physics, SPRINGER-VERLAG, as disclosed in (SPRINGER-VERLAG), (a) HYBRIDS DUSKIAN, (b) CHENN WHEEL, (c) Methods using a Ferris wheel, (d) a rotating disk for magnetic field scanning, and (e) a rotating disk for double mechanical scanning are known.

In addition, the mass separation electromagnet that selects specific ion species can be downsized, so the deflection angle of the ion beam is 60 °.
Alternatively, a 90 ° fan-shaped magnetic field is often used.

[Problems to be solved by the invention]

In the above-mentioned conventional technique, in the method using the hybrid scan of (a), since the ion beam is deflected and scanned by using the parallel electrodes, the implantation angle of the wafer of the ion beam changes, and as recently, As the element becomes finer, there is a problem in terms of driving shadow. Chain of (b)
In the method using the wheel and the ferris wheel of (c), it is difficult to cool the wafer in the case of a wafer with a photoresist forming an element pattern, and it is difficult to burn the photoresist and to automatically replace the wafer. On the other hand, the method (d) using the rotating disk for magnetic field scanning and the method (e) using the double rotating disk for mechanical scanning have a good cooling effect, but the method (d) is used. Uses an implantation angle adjusting electromagnet, there is a problem that the apparatus becomes large and the focusing property is impaired when deflecting the ion beam. In the method (e), the beam shape is constant, Since it is a complicated biaxial mechanical scan that rotates and translates the disk, the scanning speed cannot be increased, the temperature of the wafer rises, and a large and heavy disk system is operated in a high vacuum. Since it is driven, it has a drawback that it is not reliable due to the holding of vacuum and the complexity of the driving mechanism.

Further, as described above, when a fan-shaped magnetic field with an ion beam deflection angle of 60 ° or 90 ° is used, these fan-shaped magnetic fields cause the ion beam to converge on an oblique line. Since there is a drawback in that the incident angle of is changed, a method of fixing the ion beam with a constant magnetic field for mass separation is used.

The object of the present invention is to provide a compact, controllable,
It is to be able to provide a highly reliable ion implantation device.

[Means for solving problems]

In order to solve the above-mentioned problems, the configuration of the present invention has an ion source for generating ions, a mass separation electromagnet for deflecting an ion beam from the ion source by 180 °, and a wafer for implanting ions. A rotating disk mounted on the periphery of the rotating disk for high speed rotation, means for electromagnetically scanning the ion beam along the converging line of the ion beam, and an electromagnetic scanning speed of the ion beam for rotating the rotating disk. Means for controlling in proportion to the distance between the center and the center of the ion beam and in proportion to the amount of the ion beam, and the ion beam in synchronization with electromagnetic scanning of the ion beam It has a separation slit which moves along the convergent line of (1), blocks adjacent ion beams, and guides only a required ion beam to the wafer.

[Action]

The present invention employs a 180 ° -deflection type electromagnet in which the emitting direction of the ion beam is constant. Therefore, the ion beam incident on the entrance of this magnetic field flies with a radius related to the acceleration voltage of the ion beam and the magnetic field strength, and emerges at a right angle to the magnetic field. The ion beam with a constant accelerating voltage and a constant mass / charge ratio changes the orbital radius according to the magnetic field strength, but the convergence point of the emitted ion beam is aligned on the straight line at the magnetic field end, and the ion beam moves. However, since the emission angle is constant at 90 °, the angle of impact on the wafer is kept constant and is on the convergence line, as in the Dempster mass spectrometer. (Phys, Rev. 11 .316 (1918)) A mass separation electromagnet alone is used to select a specific ion species, and the ion beam is electromagnetically scanned to repeatedly scan the rotating wafer. Therefore, the intended purpose can be achieved without performing a complicated translational motion only by rotating the rotating disk on which the wafer is mounted. Further, since the ion beam can be electromagnetically scanned at high speed, it is effective for cooling the wafer.

In other words, by combining a 180 ° mass spectrometer and a rotating disk type wafer implanter, it is possible to implant ions uniformly into the wafer while keeping the implant angle and focusing conditions constant. is there.

〔Example〕

 Examples will be described below.

FIG. 1 is an explanatory view of the principle of one embodiment, 1 is an ion source, 2 is a slit, 3 and 3'is an ion beam, 4 is a separating electromagnet, 5
Is an analysis tube, 6 is a wafer, 7 is a rotating disk, 8 is an exhaust device, and 9 is a motor.

In the ion source 1, the gas is ionized by electrons or the like. The ion source 1 is normally kept at a high potential by the acceleration voltage V with respect to the ground potential slit 2, and
The ions generated in 2 are accelerated and ejected to the slit 2,
It enters the magnetic field of the separating electromagnet 4 as the ion beams 3, 3 ', .... The magnetic field forms opposing pole pieces, and an analysis tube 5 through which the ion beams 3, 3 ′, ... The direction of the magnetic flux of the magnetic field of the separation electromagnet 4 is perpendicular to the ion beams 3, 3 ′, ...
3 ', ... Are deflected as shown in FIG. As is clear from the principle of the mass spectrometer, the mass of an ion with a single charge is M, the magnetic field strength is B gauss, and the ion orbit radius is Rc.
If the energy of m and the ion is V volt, Have a relationship. Therefore, when specific ions are made to enter the magnetic field of the separation electromagnet 4 with a constant acceleration energy and the magnetic field strength B is changed, the orbit radii R, R ', ... It flies and reaches the convergence points D, D '...
In this case, since it deflects 180 °, if a uniform magnetic field is used,
The ion beam emitted slightly from the slit 2 converges at the exit end of the magnetic field of the separation electromagnet 4, the convergence point is located on the line, and the ion beams 3, 3 ′, ... Are perpendicular to the magnetic field of the separation electromagnet 4. Moreover, they appear parallel to each other. To implant the ions uniformly on the entire surface of the wafer 6, the wafer 6 and the ion beam 3,
It is necessary to traverse a large number of 3 '..., Further, when a photoresist pattern for manufacturing a semiconductor element is drawn on the wafer 6, the wafer 6 is kept at 150 ° C.
Since it is necessary to keep the value below and a large current of mA class is used, the wafer 6 is mounted around a water-cooled rotating disk 7 and is rotated at a high speed around a rotating shaft 8 to intermittently implant ions. Is used. Then, in order to improve the uniformity of implantation, the ion beam 3,
Rotating disk 7 is made to cross 3 ', ... repeatedly.
The mechanism is not complicated as in the case of translational scanning while rotating at high speed, so that excellent reliability can be obtained. The ion source 1, the ion beams 3, 3 ′, ... The rotating disk 7 is kept in a high vacuum by an exhaust device 8. The depth direction of ion implantation is controlled by keeping the accelerating voltage V constant, so that the magnetic field strength B (Gauss) of the separation electromagnet 4 is changed in order to scan like the ion beams 3, 3 ', .... You can do it. Also, the ion beam to the wafer 6
Unless the incident angles of 3,3 ', ... are kept constant, the arrangement of the crystal axes has a bearing on the relation between the penetration depth of ions called channeling and the pattern shadow of the implantation angle due to the miniaturization of semiconductor devices. Due to the problem, the implantation angle must be constant or right angle, but the characteristic of 180 ° deflection magnetic field is that the ion beam
, 3 ′, ... Converge at the end faces of the magnetic field of the separating electromagnet 4, and the emitting directions are perpendicular to the magnetic field and are parallel to each other. The scanning of ′ ... can be performed by changing the magnetic field strength B of the separating electromagnet 4, and the scanning speed can be performed electromagnetically rather than mechanically, so that higher speed scanning is possible and the number of scanning per unit time is increased. As a result, the number of times of repeated driving increases and the wafer 6 is also cooled well. The rotary disc 7 is rotated by a motor 9 via a rotary seal 8.

FIG. 2 shows the relationship between the rotating disk 7 having the wafer 6 mounted thereon and the ion beams 3, 3 ', ... At the positions of the ion beams 3 and 3', the rotating disk 7 is rotating. So
When the amount of ions is the same, the amount of ions incident within a unit time is larger in the ion beam 3 '(on the center side of the disk 7).
Also, when the amount of ions increases, the amount of incident ions at that position also increases. In any case, the ion beam at that time 3,
By increasing the scanning speed of 3 ', the amount of incident ions per unit time can be kept constant and uniform implantation becomes possible.

According to the ion implantation apparatus of this embodiment, it is possible to scan the ion beam at high speed with the mass separation electromagnet on the wafer implantation surface while keeping the beam convergence and the implantation angle constant. With a simple structure, uniform ion implantation is possible, and there is an effect that the device can be downsized. That is, since no special magnetic field for ion beam scanning or mechanical scanning is required, the controllability and reliability of the apparatus are improved and the cost is reduced.

FIG. 3 is an explanatory view of the principal part showing the principle of another embodiment, in which the omitted parts are the same as those in FIG. 1, and the same parts as those in FIG. Reference numeral 10 is a separation slit, 11 is a bellows, 12 is a slit scanning mechanism, and 13 is a scanning controller. Arrows indicate the movement directions of the slit and the ion beam.

In the ion implantation apparatus of the embodiment shown in FIG. 1, the ion beam 3,
If 3 ', ... are different ion species, their convergence position
When D, D ′, ... Are smaller than the size of the wafer 6, that is, when the mass of the ions is large, different ions are implanted in the wafer 6. The ion implanter of this embodiment is used in such a case, and is provided with a separation slit 10 at the converging point so that only a specific ion beam passes in conjunction with electromagnetic scanning. is there.

In this embodiment, the bellows 11 is used to move the separation slit 10 in a vacuum. Separation slit 10 is provided by slit scanning mechanism 12 (for example, ball screw rotary feed).
In conjunction with the magnetic field scanning, the scanning control device causes the ion beams 3, 3 ', ... The opening width of the separation slit 10 may be set depending on the ion species to be implanted. That is, at the start of implantation, the ion beam 3 is present at one end of the wafer 6 shown by the point A in FIG.
When the magnetic field strength of the separating electromagnet 4 is increased, the ion beam 3 moves in the direction of the ion beam 3 '. The separation slit 10 is moved in the same direction as the ion beam shown by the point B in FIG. 3 in conjunction with the ion beams 3 and 3 ', and ion implantation is performed on the entire surface of the wafer 6. It goes without saying that the moving speed at this time is controlled so that the number of ions per unit time becomes constant depending on the position of the wafer 6 according to the moving speed of the ion beam and the ion beam intensity.

The ion implanting device of this embodiment is also used in the same manner as the above-mentioned embodiment and the same effect can be obtained, but it is particularly effective when the converging positions of different ion species are adjacent to each other.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY The present invention can provide a compact, highly controllable and reliable ion implanter capable of uniform implantation, and has a great industrial effect.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the ion implantation apparatus of the present invention,
FIG. 2 is an explanatory view of the relationship between the wafer and the ion beam, and FIG. 3 is an explanatory view of the essential parts of another embodiment. 1 ... Ion source, 2 ... Slit, 3, 3 '... Ion beam,
4 ... Separation electromagnet, 5 ... Analysis tube, 6 ... Wafer, 7 ... Rotating disk, 9 ... Rotation drive mechanism, 10 ... Separation slit, 12 ... Slit scanning mechanism, 13 ... Scan control device.

Claims (1)

[Claims] 1. An ion source for producing ions, a mass separation electromagnet for deflecting an ion beam from the ion source by 180 °, and a rotating disk having a wafer on which ions are implanted mounted on its peripheral portion and rotating at a high speed. A means for electromagnetically scanning the ion beam along a convergence line of the ion beam, and an electromagnetic scanning speed of the ion beam at a distance between a rotation center of the rotating disk and a center of the ion beam. Means for controlling in inverse proportion and proportionally to the magnitude of the amount of the ion beam, and an ion beam which moves along the convergent line of the ion beam in synchronism with electromagnetic scanning of the ion beam, And an isolation slit that guides only the required ion beam to the wafer.